Center for Pulsed Power and Power Electronics.
TTU Home Edward E. Whitacre Jr. College of Engineering P3E Home Faculty

Dr. Stephen Bayne

Professor and ECE Department Chair

Contact Information

Department of Electrical and Computer Engineering
Texas Tech University
Lubbock, TX 79409-3102

Phone: (806) 834-0526
Fax: (806)742-1281
stephen.bayne@ttu.edu

Research Interests

Recent and Current Positions

   Curriculum Vitae

Education

Publications


Journal

Publication Year:  2022
+ Centralized Control Topology For Pv Farms Shading Detection And Gmpp Searching Restarting Condition
  C. A. Negri; S. Daneshvardehnavi; K. E. K. Schmitt; A. Esmaeel Nezhad; P. H. J. Nardelli; S. Bayne; M. G. Giesselmann
Abstract:  The power output of the solar panels follows a power-voltage (P-V) characteristic containing only one Global Maximum Point (GMP) in the normal conditions. However, under Partial Shading Conditions (PSC), the unbalanced irradiance in the panels creates Local Maximum Points (LMP) in the P-V curve. Standard control techniques for Maximum Power Point Tracking (MPPT) can not properly locate the GMP, stagnating in LMPs and generating losses in the energy harvesting. Specific techniques to locate the GMP are presented in the literature. However, the condition to restart the GMP is not widely discussed. The main challenges of global search algorithms are related to the restarting conditions. Avoiding unnecessary searching and providing an assertive GMP restarting condition is crucial for PV systems operation. In every GMP search, the solar inverters oscillate the power exchanged with the grid, causing frequency and voltage variations depending on the size of the PV plant. This paper proposes a novel technique that uses a centralized controller to identify the shaded inverters, creating flags that locally start the GMP searching. The solution minimizes the number of times the search is performed by providing an assertive GMP restarting condition, saving energy, and avoiding unnecessary output power oscillation. The proposed control technique was evaluated using the data of a real 150-kW solar farm containing five inverters with two MPPT trackers each.

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+ Dynamic Voltage Restorer (Dvr) With A Novel Robust Control Strategy
  DaneshvarDehnavi, S; Negri, C; Bayne, S; Giesselmann, M
Abstract:  With the advancement of technology, electric equipment and loads have become more sensitive to problems related to power quality, such as voltage sag, swell, imbalances, and harmonics. To detect faults and to protect sensitive loads from these voltage distortions, a Dynamic Voltage Restorer (DVR) series compensator is among the best available cost-effective solutions. One of the main goals of the DVR is to achieve a control structure that is robust, stable, and can handle properly the disturbances (e.g., grid voltage issues, load current, and fluctuations at the DC link voltage) and model uncertainties (e.g., inverters and filter parameters). In this work, a novel framework control strategy based on Uncertainty and Disturbance Estimator (UDE) is proposed to improve the response of the DVR to properly compensate the load voltage under a variety of power quality issues, particularly the ones associated with the grid voltage disturbances. Additionally, the stability of the proposed control system is analyzed and validated using the Lyapunov stability theory. The advantages of the new control system are robustness, simplified design, good harmonic rejection, low tracking error, fast response, and sinusoidal reference tracking without the need for voltage transformations or specific frequency tuning (e.g., abc-dq0 and Proportional-Resonant). This research uses the MATLAB/Simulink software to validate the effectiveness of the proposed scheme under a diverse set of conditions with no control limitations. Moreover, the designed controller is tested under real conditions using Hardware-In-theLoop (HIL) validation with OPAL-RT real-time simulator coupled with a TI Launchpad microcontroller. The results demonstrate a good performance of the proposed control strategy for a quick transient response and a great harmonic rejection when subject to grid voltage distortions. (c) 2021 ISA. Published by Elsevier Ltd. All rights reserved.
Publication Year:  2021
+ Can 100% Renewable Power System Be Successfully Built?
  DaneshvarDehnavi, S; Negri, CA; Giesselmann, MG; Bayne, SB; Wollenberg, B
Abstract:  Global warming has been a critical issue in recent years. Many leaders and politicians have talked about replacing fossil fuels with Renewable Energy Resources (RES). Some of them even went further and are talking about running a country with 100% RES soon. Is that economically viable? What would be the estimated cost of such a system? In this paper, a city in west Texas with a 100 MW peak load has been assumed to operate with the wind, solar, and Battery Energy Storage System (BESS) totally disconnected from the grid for a cost evaluation. Real generation and load time series data are used to achieve an optimum combination of the installed capacity of those resources by minimizing the total overnight cost, respecting a maximum of 24 h of faults in which the system cannot provide the load during the period. A Monte Carlo simulation is applied to the previous results to evaluate the influence of faulty devices and increase the robustness of the system. The results for both cases are analyzed and compared. Finally, the total cost of install capacity will be compared with other non-renewable resources. (c) 2021 Elsevier Ltd. All rights reserved.
+ Demonstration Of Constant-Gate-Charge Scaling To Increase The Robustness Of Silicon Carbide Power Mosfets
  J. A. Cooper; D. T. Morisette; M. Sampath; C. A. Stellman; S. B. Bayne; M. J. Westphal; C. H. Anderson; J. A. Ransom
Abstract:  We introduce the concept of constant-gate-charge scaling to increase the short-circuit withstand time of SiC power MOSFETs without increasing their ON-state resistance, gate charge, or oxide field. In gate-charge scaling, we scale the oxide thickness and gate drive voltage, keeping the oxide field constant. Short-circuit measurements on 1200 V SiC double-implanted MOSFETs (DMOSFETs) confirm that short-circuit withstand times can be increased by 2- 4× without increasing ON-resistance, simply by reducing the oxide thickness and the gate drive voltage.

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+ Doping-Less Sic P-I-N Diode: Design And Investigation
  S. Hahmady; S. Bayne
Abstract:  We introduce a novel high-voltage SiC p-i-n diode considering a charge plasma approach. This technique facilitates the formation of the anode and the cathode regions within the silicon carbide without requiring any impurity doping by taking advantage of the work-function difference between silicon carbide and metal electrodes. Utilizing the 2-D TCAD simulation, we represent the performance of the proposed doping-less silicon carbide p-i-n diode is analogous to the silicon carbide Schottky diode in terms of forward and reverse characteristics as well as temperature dependency. As opposed to the conventional (doped) silicon carbide p-i-n diode, the doping-less silicon carbide p-i-n diode holds a lower ON-state voltage drop and higher reverse saturation current. Although the doping-less silicon carbide p-i-n diode has the merits of the silicon carbide Schottky diode, but it has leverage over the corresponding counterparts by eliminating the doping and the high thermal budget fabrication processes.

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Publication Year:  2020
+ Commercial Gan-Based Power Electronic Systems: A Review
  Pushpakaran, BN; Subburaj, AS; Bayne, SB
Abstract:  Wide bandgap semiconductor technology is gaining widespread acceptance in the area of high-power and high-temperature power electronics. Gallium nitride (GaN) not only has a wide bandgap of 3.4 eV and all the associated superior electronic properties but also enables the development of high-mobility power devices which is critical in increasing the power density of a power electronics system. Since a commercial GaN power transistor has a lateral structure as opposed to the traditional vertical device structure, commercially available devices are rated below 1000 V breakdown voltage with a maximum value of 900 V and typical value around 650 V. The primary focus of this review will be to introduce readers to the commercially available power electronic systems developed by various manufacturers which employ GaN-based power devices and highlight their remarkable performance which surpasses existing technology. This review also includes a brief introduction on GaN technology followed by current market study showing the roadmap of integration of GaN-based power electronics in the power industry.
+ Evaluation Of Long-Term Reliability And Overcurrent Capabilities Of 15-Kv Sic Mosfets And 20-Kv Sic Igbts During Narrow Current Pulsed Conditions
  M. Kim; J. J. Forbes; E. A. Hirsch; J. Schrock; S. Lacouture; A. Bilbao; S. B. Bayne; H. K. O"™Brien; A. A. Ogunniyi
Abstract:  Silicon carbide (SiC) is becoming a preferred technology of choice for power dense application compared with silicon (Si). A more comprehensive analysis of the long-term pulsed power reliability of SiC is necessary so that the technology can make the transition commercially. In this article, a testbed is utilized to evaluate research grade 15-kV SiC MOSFETs and 20-kV SiC IGBTs manufactured by Wolfspeed, a Cree Company. A testbed was developed here at Texas Tech University (TTU), Lubbock, TX, USA, to test these two devices. The narrow pulse testbed's capacitor bank can be charged up to 10 kV and output square waveform pulse up to 2.0 μs. The waveform has a fullwidth at half-maximum pulse and is tested at a repetition pulse rate of three seconds. The electrical characteristics of the forward conduction and reverse breakdown of the device under test (DUT) are measured periodically during the experiment. The DUTs were pulsed at different current levels, up to 340 A (1.06 kA/cm2) for the IGBTs and 74 A (296 A/cm2) for MOSFETs, while the electrical device degradation was monitored. This work discusses the results of the long-term pulsed power reliability, failure modes, and their robustness in overcurrent operations of highpower SiC MOSFETs and IGBTs.

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+ Guest Editorial
  S. Bayne; R. Allen; B. Srinivasan
Abstract:  The Guest Editor team of this Special Issue of the IEEE Transactions on Plasma and Science (TPS) is very excited to present this technical issue that encompasses various topics currently being studied within the field of pulsed power science and technology (PPST). Many articles for this Special Issue came from contributors (much like past Special Issues) who participated in the 2019 IEEE Pulsed Power and Plasma Science Conference (PPPS 2019), which comprised the 22nd Biennial PPC Conference and the 46th Annual ICOPS conference. The combined conference was held in Orlando, FL, USA, in June 23"“28, 2019 (http://www.ppps2019.org/). Both PPC and ICOPS conferences continued a strong history of serving their community by providing a platform for members to give presentations and have discussions in their field of research. Although this Special Issue was prepared during the COVID-19 Pandemic, the editorial team and reviewers worked very hard to make this a very successful Special Issue.

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+ Reverse Recovery Of 50 V Silicon Charge Plasma Pin Diode
  S. Hahmady; S. Bayne
Abstract:  In this article, a novel approach is used for the first time to design a high-voltage PIN diode without any chemical doping process of cathode and anode region. This approach favors "p" and "n" plasma region formation through various metal contacts with appropriate work-functions for anode and cathode respectively. In this study, the forward and reverse characteristics, as well as the switching performance (reverse recovery) of this novel device, charge plasma (CP) PIN diode, were compared with the Schottky diode and the conventional PIN diode using TCAD simulation.

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+ Wind Turbine Wake Position Detection And Rotor Speed-Based Wake Steering Validation In A Wind Tunnel Wake Simulator
  Castillo, R; Bayne, S; Pol, S; Westergaard, C
Abstract:  Wind farm control has demonstrated power production improvements using yaw-based wake steering compared to individual turbine optimization. However, slower yaw actuation rates in response to rapid inflow changes lend to impracticality of yaw-based steering, as it causes time-varying downstream rotor-wake overlap, power production fluctuation, and consequent reduction. Therefore, closed-loop wake control is required to mitigate wake deflection uncertainty. To respond to rapid inflow variations, rotor speed actuated is investigated here. Furthermore, wake position information is required as feedback for closed-loop control function. For field-installed turbines, nacelle-based Light detection and ranging (LIDAR) is expected to provide this information. So far, LIDAR-derived wake position has been determined through model-based field reconstruction of scattered LIDAR data. However, this requires sophisticated, economically prohibitive LIDARs. To incorporate inexpensive, two-beam LIDAR for wake detection, a tip vortex-based approach was developed and is also presented here. These contributions can be considered as intermediate steps toward realization of a novel closed-loop wake control.
Publication Year:  2019
+ Cost And Availability Optimization Of Wind Energy With Distributed Energy Resources Of A Microgrid
  Ramabhotla, S; Bayne, SB
Abstract:  A microgrid, an emerging technology in the electric power systems, has various benefits due to the implementation of distributed energy sources along with the loads. A microgrid utilizing the wind energy, solar energy, combined heat and power, natural gas generator, diesel generator, and battery storage is considered in an islanded mode of operation. The economic dispatch optimization is implemented using a reduced gradient algorithm to optimize the Operation and Maintenance cost in the islanded mode of the microgrid. The cost of each energy source is evaluated for every hour of the day using MATLAB code. Then, the availability of each energy source in the microgrid is evaluated. The results obtained are validated by comparing the Operation and Maintenance cost and the availability of each energy source in the microgrid. The optimal solution is achieved by considering the change in wind forecast and battery energy storage profiles.
+ Demonstration Of A Tritiated Nitroxide Nuclear Battery
  Russo, J; Litz, M; Ray, W; Bayne, S; Rosen, GM; Cho, H; Yu, J; Bigio, DI; Thomas, C; Alam, TR
Abstract:  Unattended, compact, terrestrial and space sensors require sources that have high energy and power densities to continuously operate for 3 to 99 years depending on application. Currently, chemical sources cannot fully satisfy these applications, especially in solid state form. Betavoltaic (beta V) nuclear batteries using beta(-)-emitting radioisotopes possess energy densities 1000 times greater than conventional chemical sources. Their power density is a function of fl flux saturation point relative to the planar (2D) configuration, beta(-) emission range, and the semiconductor converter, the betavoltaic (beta V) cell, properties. The figure of merit is the beta (beta(-))-flux surface power density (P-beta- in mu W-n per cm(2) footprint), where an optimal portion of incident beta particles penetrates the surrounding semiconductor depletion region. Tritiated nitroxides are favorable radioisotope sources with the potential to have the highest specific activity (A(m) in Ci/g) and P-beta- for an organic compound in solid form. The goal of this research is to demonstrate a tritiated nitroxide nuclear battery using the planar (2D) coupling configuration. The reproducible tritiation procedure produced stable product with a A(m) of approximately 635 Ci/g, which was 70% of the theoretical A(m). For the nuclear battery demonstration, the tritiated nitroxide, dissolved in methanol, was deposited on a 4H-SiC beta V and InGaP photovoltaic (PV) cell using a dispensing apparatus and micropipette. Both devices' characteristics were measured beforehand using a controlled electron beam source to approximate the surface radioactivity from the deposited radioisotope. The maximum power point (MPP) of the 4H-SiC and InGaP were 7.77 nW/cm(2) and 1.63 nW/cm(2) with 100 mCi and 67 mCi, respectively. The power and total efficiency were lower than expected due to partial solvent evaporation and droplet thickness. Numerical models using MCNP6 Monte Carlo code were used to simulate an optimal nuclear battery prototype. The models' accuracy was confirmed with the device calibration curves and a previous metal tritide model based on empirical results. Based on optimal model results, the tritiated nitroxide saturation layer thickness (D-0.99) and P-beta-(D-0.99) were 10 mu m and 558 nW/cm(2), respectively, using a 4H-SiC.
Publication Year:  2018
+ Guest Editorial Special Issue On Pulsed Power Science And Technology
  S. Bayne; B. Novac; H. O"™Brien; H. Li
Abstract:  This special issue of the IEEE TRANSACTIONS ON PLASMA SCIENCE (TPS) mainly contains works presented at the 21st IEEE International Pulsed Power Conference (PPC) held in Brighton, U.K., between June 18"“22, 2017 (http://ece-events.unm.edu/ppc2017/). This conference marks an important step, as it was located outside of the USA for the first time. The PPC is well known for serving the Pulsed Power and Plasma Science communities as the principal forum for the professionals worldwide, where the most important technical presentations and discussions are taking place; the Brighton conference was no exception. The 21st PPC was extremely successful, with 470 quality papers submitted as equal contributions from the Americas, Europe, and Asia.

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+ Single-Pulse Avalanche Mode Operation Of 10-Kv/10-A Sic Mosfet
  Kelley, MD; Pushpakaran, BN; Bilbao, AV; Schrock, JA; Bayne, SB
Abstract:  The high-voltage silicon carbide MOSFET is a state-of-the-art solution for increasing power density and efficiency in power electronics; nonetheless, a full-scope of failure modes during extreme operating condition has not been established. Past efforts evaluated short-circuit capability of 10-kV silicon carbide MOSFET, however, in this manuscript, the single-pulse avalanche mode operation of a research-grade 10-kV/10-A silicon carbide MOSFET is explored for the first time. A decoupled undamped inductive circuit was selected for evaluation, and avalanche energy was increased until catastrophic failure occurred. The maximum tolerable avalanche energy was measured to be 2.84 J corresponding to an energy density of 8.8 &cm(-2). This result was compared with 1.2 kV silicon carbide MOSFETs to evaluate device robustness. Post failure analysis included: estimation of junction temperature, scanning electron microscopy, and focused ion beam cut. Peak junction temperature of 1010 degrees C was estimated using a thermal RC model and measurement results suggested gate degradation as the primary mechanism responsible for device destruction. Microscopy of the device validated gate failure which occurred at, or beneath, the gate metallization. A narrow cavity with-in the failure region was discovered during failure analysis and is hypothesized to have protruded the epitaxial region of the semiconductor.
Publication Year:  2017
+ An Open Circuit Voltage Decay System For Performing Injection Dependent Lifetime Spectroscopy
  Lacouture, S; Schrock, J; Hirsch, E; Bayne, S; O'Brien, H; Ogunniyi, AA
Abstract:  Of all of the material parameters associated with a semiconductor, the carrier lifetime is by far the most complex and dynamic, being a function of the dominant recombination mechanism, the equilibrium number of carriers, the perturbations in carriers (e.g., carrier injection), and the temperature, to name the most prominent variables. The carrier lifetime is one of the most important parameters in bipolar devices, greatly affecting conductivity modulation, on-state voltage, and reverse recovery. Carrier lifetime is also a useful metric for device fabrication process control and material quality. As it is such a dynamic quantity, carrier lifetime cannot be quoted in a general range such as mobility; it must be measured. The following describes a stand-alone, wide-injection range open circuit voltage decay system with unique lifetime extraction algorithms. The system is initially used along with various lifetime spectroscopy techniques to extract fundamental recombination parameters from a commercial high-voltage PIN diode. Published by AIP Publishing.
+ Electrothermal Simulation-Based Comparison Of 4H-Sic P-I-N, Schottky, And Jbs Diodes Under High Current Density Pulsed Operation
  B. N. Pushpakaran; S. B. Bayne; A. A. Ogunniyi
Abstract:  Pulsed power applications are characterized by very high instantaneous power due to the high voltage and current involved. Power diodes used as a closing switch in pulsed power circuits must be able to withstand the high current operation well above the continuous device rating, for a transient duration. Due to the superior electrothermal properties of wide bandgap Silicon Carbide (SiC) material, it is feasible to develop high Blocking Voltage (BV) Schottky and Junction Barrier Schottky (JBS) diodes besides p-i-n rectifiers. In order to evaluate the device performance under high current density pulsed operation, 2-D models of SiC p-i-n, Schottky, and JBS diodes rated for 3.3-kV BV and 100 A/cm2 current density were developed using Silvaco ATLAS TCAD software. The diode structures were simulated electrothermally to study the device behavior and compare the performance under high current density pulsed operation. The power dissipation and the lattice temperature profile of the SiC diodes were analyzed to compare the magnitude of heat loss and formation of thermal hot spot in the diode structure to predict the suitability of the device for pulsed power applications.

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+ Single-Pulse Avalanche Mode Robustness Of Commercial 1200 V/80 Mω Sic Mosfets
  M. D. Kelley; B. N. Pushpakaran; S. B. Bayne
Abstract:  Commercialization of 1200-V silicon carbide (SiC) MOSFET has enabled power electronic design with improved efficiency as well as increased power density. High-voltage spikes induced in applications such as solenoid control, solid-state transformer, boost converter, and flyback converter can drive the MOSFET into avalanche mode operation due to high di/dt coupled with parasitic inductance. Avalanche mode operation is characterized by high-power dissipation within the device due to the high voltage and current crossover. This study focuses on the evaluation of two commercially available SiC MOSFETs from different manufacturers, each rated for 1200 V with an ON-state resistance of 80 mΩ, during unclamped inductive switching (UIS) mode operation. To determine device reliability, a decoupled UIS testbed was developed to evaluate the avalanche energy robustness at 22 °C and 125 °C during two specific conditions: high current and low energy, and low current and high energy. The SiC MOSFETs were evaluated using a load inductance of 1.42, 5.1, 10.5, and 15.8 mH to understand the effect of current and avalanche energy on device failure. To correlate the experimental results with the failure mechanism, estimated junction temperature and static device characteristics are presented; additionally, MOSFETs were decapsulated to examine the failure sites on the semiconductor die.

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+ Towards Kilohertz Electrochemical Capacitors For Filtering And Pulse Energy Harvesting
  Fan, ZY; Islam, N; Bayne, SB
Abstract:  Electrochemical capacitors (ECs) are slow devices with charging and discharging rates limited below 1 Hz. They run at direct current and function as power source, but cannot afford the role of a conventional capacitor for current ripple filtering or pulse energy harvesting. Recently, developing ultrafast ECs that work at hundreds to kilohertz (kHz) frequency scope have attracted great interests, with the aim to replace the traditional aluminum electrolytic capacitors (AECs) that have bulky size and large equivalent series resistance. Compact kHz ECs would produce huge impacts on power design, power electronics and environmental pulse energy harvesting. Towards such a goal, the electrode material and its nanostructure are the keys to boost the response frequency of an EC from below 1 Hz to above 1 kHz. In this Review, we summarize guidelines on the electrode nanostructure design for kHz response, discuss the various carbonaceous materials and other highly conductive materials based electrode structures for kHz ECs. The configurations of higher voltage kHz ECs, and their dimension advantage over AECs are critically evaluated, followed with the outlook on the further study and development in this promising area.
Publication Year:  2016
+ A 500 A Device Characterizer Utilizing A Pulsed-Linear Amplifier
  Lacouture, S; Bayne, S
Abstract:  With the advent of modern power semiconductor switching elements, the envelope defining high power is an ever increasing quantity. Characterization of these semiconductor power devices generally falls into two categories: switching, or transient characteristics, and static, or DC characteristics. With the increasing native voltage and current levels that modern power devices are capable of handling, characterization equipment meant to extract quasi-static IV curves has not kept pace, often leaving researchers with no other option than to construct ad hoc curve tracers from disparate pieces of equipment. In this paper, a dedicated 10 V, 500 A curve tracer was designed and constructed for use with state of the art high power semiconductor switching and control elements. The characterizer is a physically small, pulsed power system at the heart of which is a relatively high power linear amplifier operating in a switched manner in order to deliver well defined square voltage pulses. These actively shaped pulses are used to obtain device's quasi-static DC characteristics accurately without causing any damage to the device tested. Voltage and current waveforms from each pulse are recorded simultaneously by two separate high-speed analog to digital converters and averaged over a specified interval to obtain points in the reconstructed IV graph. (C) 2016 AIP Publishing LLC.
+ Analysis Of Equivalent Circuit Of The Utility Scale Battery For Wind Integration
  A. S. Subburaj; S. B. Bayne; M. G. Giesselmann; M. A. Harral
Abstract:  This paper provides steady-state and transient analysis of the equivalent circuit of the 1 MWh battery tied to the grid for wind integration. It also discusses the installation of a 1 MWh battery system at Reese Technology Center (RTC) in Lubbock, Texas. The research involves deploying energy storage devices for application with wind turbine model to understand the transient behavior of the system under three phase fault conditions. A 1 MW/1 MWh battery storage system at the RTC is connected to the South Plains Electric Cooperative (SPEC) grid. The batteries are used for energy storage and for mitigation of transient conditions grid dynamics. In this paper, the equivalent circuit of the 1 MWh battery is modeled in PSCAD and analyzed for its charge and discharge characteristics under transient fault conditions when it is tied to the grid for wind integration.

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+ Characterization Of An N-Type 4-Kv Gto For Pulsed Power Applications
  T. Flack; C. Hettler; S. Bayne
Abstract:  This paper details the experimental evaluation and simulation of a 4-kV n-type gate turn-OFF thyristor (GTO) designed for pulsed power applications. The primary criteria of evaluation are rate of current rise (dI/dt), turn-ON delay time (TD), and resistance of the device during turn-ON transients [RON(t)]. The device under test (DuT) is an n-type asymmetric-blocking GTO manufactured by Silicon Power (Part No. 14N40A10) with a rated dc blocking voltage of 4 kV. A test circuit was specifically designed to minimize stray inductance in order to capitalize on the dI/dt capabilities of the DuT. Experimental data collected from resistance measurements are used to develop a single-switch approximate model for use in simulation. The results of dI/dt experiments provide a profile of DuT dI/dt operation beyond rated values; specifically dI/dt values >70 kA/μs were readily achieved. The turn-ON delay time of the DuT is also characterized and determined to be ~225 ns on average.

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+ Failure Analysis Of 1200-V/150-A Sic Mosfet Under Repetitive Pulsed Overcurrent Conditions
  J. A. Schrock; B. N. Pushpakaran; A. V. Bilbao; W. B. Ray; E. A. Hirsch; M. D. Kelley; S. L. Holt; S. B. Bayne
Abstract:  SiC MOSFETs are a leading option for increasing the power density of power electronics; however, for these devices to supersede the Si insulated-gate bipolar transistor, their characteristics have to be further understood. Two SiC vertically oriented planar gate D-MOSFETs rated for 1200 V/150 A were repetitively subjected to pulsed overcurrent conditions to evaluate their failure mode due to this common source of electrical stress. This research supplements recent work that demonstrated the long term reliability of these same devices [1]. Using an RLC pulse-ring-down test bed, these devices hard-switched 600 A peak current pulses, corresponding to a current density of 1500 A/cm2. Throughout testing, static characteristics of the devices such as BVDSS, RDS (on), and VGS(th) were measured with a high power device analyzer. The experimental results indicated that a conductive path was formed through the gate oxide; TCAD simulations revealed localized heating at the SiC/SiO2 interface as a result of the extreme high current density present in the device's JFET region. However, the high peak currents and repetition rates required to produce the conductive path through the gate oxide demonstrate the robustness of SiC MOSFETs under the pulsed overcurrent conditions common in power electronic applications.

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+ Failure Modes Of 15-Kv Sic Sgto Thyristors During Repetitive Extreme Pulsed Overcurrent Conditions
  J. A. Schrock; E. A. Hirsch; S. Lacouture; M. D. Kelley; A. V. Bilbao; W. B. Ray; S. B. Bayne; M. Giesselmann; H. O'Brien; A. Ogunniyi
Abstract:  SiC SGTO thyristors are an advanced solution for increasing the power density of medium voltage power electronics. However, for these devices to replace Si thyristor technology in industrial applications their characteristics and failure modes must be understood. This letter presents the failure modes of two 15-kV SiC SGTO thyristors during repetitive overcurrent conditions. The devices were evaluated with 2-kA (3.85 kA/cm2) square pulses of 100 μs duration using a pulse forming network. Throughout testing, each devices' static characteristics were analyzed for signs of degradation; upon degradation, testing was ceased and the physical failure mode was determined through imaging with a scanning electron microscope (SEM) in conjunction with a focused ion beam. The electrical results demonstrate the failure modes of both SiC SGTO thyristors during pulsed overcurrents electrically manifested themselves as a conductive path through the gate-anode junction and an increased device on-state voltage. SEM imaging revealed one SiC thyristor formed an approximately 10-μm wide cylindrical void, and the second SiC thyristor formed an approximately 200-μm long crack. However, the experimental results demonstrate these 15-kV SiC SGTO thyristors' robust ability to repetitively switch at extreme high current density for tens of thousands of cycles.

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+ Gan Technology For Power Electronic Applications: A Review
  Flack, TJ; Pushpakaran, BN; Bayne, SB
Abstract:  Power semiconductor devices based on silicon (Si) are quickly approaching their limits, set by fundamental material properties. In order to address these limitations, new materials for use in devices must be investigated. Wide bandgap materials, such as silicon carbide (SiC) and gallium nitride (GaN) have suitable properties for power electronic applications; however, fabrication of practical devices from these materials may be challenging. SiC technology has matured to point of commercialized devices, whereas GaN requires further research to realize full material potential. This review covers fundamental material properties of GaN as they relate to Si and SiC. This is followed by a discussion of the contemporary issues involved with bulk GaN substrates and their fabrication and a brief overview of how devices are fabricated, both on native GaN substrate material and non-native substrate material. An overview of current device structures, which are being analyzed for use in power switching applications, is then provided; both vertical and lateral device structures are considered. Finally, a brief discussion of prototypes currently employing GaN devices is given.
+ Impact Of Silicon Carbide Semiconductor Technology In Photovoltaic Energy System
  Pushpakaran, BN; Subburaj, AS; Bayne, SB; Mookken, J
Abstract:  The increased awareness of the significance of solar energy has led to intensified research in the areas of solar energy harvesting. To increase the cost effectiveness of the generation of solar power, silicon carbide (SiC) power devices are playing a major role in the power electronics technology due to its superior material properties compared to Silicon (Si). The photovoltaic (PV) inverter is a major component in the solar energy conversion system whose performance relies on the efficient design of power electronics. In order to obtain maximum power from the solar panels, the power loss in the energy conversion system must be minimized by proper selection of semiconductor devices and thereby minimizing the number of power electronic components used. The necessity to reduce the overall switch mass and volume have led to the development of advanced high-power, high-temperature semiconductor materials such as SiC. The performance improvements are based on superior material properties of SiC, such as: bandgap of 3.26 eV, critical breakdown field of 2-4 MV/cm, thermal conductivity of 4.9 W/(cm K), and a saturated drift velocity of 2 x 10(7) cm/s. The aforementioned properties of SiC highlight the importance of silicon carbide semiconductor technology. Some of the limitations of the technology include higher device cost due to emerging technology, and need for high-temperature packaging techniques. Future research includes methods to reduce manufacturing cost, packaging issues, and also face challenges to increase the performance and reliability of SiC devices. The focus of the paper is to discuss the role of SiC semiconductor based power electronics technology in PV energy conversion system. The comparisons and analysis of various PV inverter system prototypes imply that the application of SiC power semiconductor devices in a PV energy system can help eliminate several issues which are at present due to the material limitations of silicon. (C) 2015 Elsevier Ltd. All rights reserved.
+ Physics-Based Simulation Of 4H-Sic Dmosfet Structure Under Inductive Switching
  Pushpakaran, BN; Bayne, SB; Ogunniyi, AA
Abstract:  The integration of high power silicon carbide (SiC) Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) in today's power systems drives the demand for deeper understanding of the device switching characteristics by way of device simulation. Applications like motor drive require power MOSFETs to drive highly inductive loads which increase the switching power loss by extending the voltage and current crossover, a situation which gets exacerbated by the presence of parasitic inductance. A 2D model of a 1200 V 4H-SiC vertical DMOSFET half-cell was developed using a commercially available TCAD software package to investigate the electro-thermal switching characteristics using clamped inductive switching circuit for ON state drain current density values up to at an ambient lattice temperature of 300 K. Device physics-based models were included to account for carrier mobility, carrier generation and recombination, impact ionization and lattice heating. In order to analyze the areas of localized lattice heating, the lattice temperature distribution was monitored during simulation. The clamped inductive switching circuit simulations were performed with and without the addition of parasitic electrode inductance to observe the difference in switching energy loss.
+ Suitability Of N-On Recessed Implanted Gate Vertical-Channel Sic Jfets For Optically Triggered 1200 V Solid-State Circuit Breakers
  Veliadis, V; Steiner, B; Lawson, K; Bayne, SB; Urciuoli, D; Ha, HC
Abstract:  A requirement for the commercialization of power SiC transistors is their long term reliable operation under the hard-switching conditions and high temperatures encountered in the field. Normally ON 1200 V vertical-channel implanted-gate SiC junction field effect transistors (JFETs), designed for high-power bidirectional (four quadrant) solid-state-circuit-breaker (SSCB) applications, were repetitively pulse hard switched at 150 degrees C from a 1200 V blocking state to an ON-state current of 115 A, which is in excess of 13 times the JFET's 250-W/cm(2) rated current at 150 degrees C. The JFETs were fabricated in seven photolithographic levels with a single masked ion-implantation forming the p+ gates and guard rings, and with no epitaxial regrowth. The pulsed testing was performed using a low inductance RLC circuit. In this circuit, energy initially stored in a capacitor is discharged in a load resistor through the JFET under test. The JFET hard-switch stressing included over 2.4 million 1200 V/115-A hard-switch events at 150 degrees C and at a repetition rate of 10 Hz. The peak energies and powers dissipated by the JFET at each hard-switch event were 73.2 mJ and 68.2 kW, respectively. The current rise rate was 166 A/mu s and the pulse full width at half maximum (FWHM) was 1.8 mu s. After over 2.4 million hard-switch events at 150 degrees C, the JFET blocking voltage characteristics remained unchanged while the ON-state conduction slightly improved, which indicate reliable operation. An optically triggered SSCB, based on these rugged JFET, is proposed.
Publication Year:  2015
+ Development And Testing Of An Active High Voltage Saturation Probe For Characterization Of Ultra-High Voltage Silicon Carbide Semiconductor Devices
  Bilbao, AV; Schrock, JA; Ray, WB; Kelley, MD; Holt, SL; Giesselmann, MG; Bayne, SB
Abstract:  Obtaining accurate collector to emitter voltage measurements when characterizing high voltage silicon carbide (SiC) devices requires the ability to measure voltages in the range of zero to 10 V while the device is in the on-state and the ability to withstand ultra-high voltages while the device is in the off-state. This paper presents a specialized voltage probe capable of accurately measuring the aforementioned range. A comparison is made between the proposed probe and other commonly used high voltage probe alternatives in relation to high voltage SiC device testing. Testing of the probe was performed to ensure linearity, high accuracy, and high bandwidth. (C) 2015 AIP Publishing LLC.
+ High-Mobility Stable 1200-V, 150-A 4H-Sic Dmosfet Long-Term Reliability Analysis Under High Current Density Transient Conditions
  J. A. Schrock; W. B. Ray II; K. Lawson; A. Bilbao; S. B. Bayne; S. L. Holt; L. Cheng; J. W. Palmour; C. Scozzie
Abstract:  For SiC DMOSFETs to obtain widespread usage in power electronics their long-term operational ability to handle the stressful transient current and high temperatures common in power electronics needs to be further verified. To determine the long-term reliability of a single 4H-SiC DMOSFET, the effects of extreme high current density were evaluated. The 4H-SiC DMOSFET has an active conducting area of 40 mm2, and is rated for 1200 V and 150 A. The device was electrically stressed by hards-witching transient currents in excess of four times the given rating (>600 A) corresponding to a current density of 1500 A/cm2. Periodically throughout testing, several device characteristics including RDS(on) and VG S(th) were measured. After 500 000 switching cycles, the device showed a 6.77% decrease in RDS (on), and only a 132-mV decreased in VG S(th). Additionally, the dc characteristics of the device were analyzed from 25 to 150 °C and revealed a 200-mV increase in on-state voltage drop at 20 A and a 2-V reduction in VG S(th) at 150 °C. These results show this SiC DMOSFET has robust long-term reliability in high-power applications that are susceptible to pulse over currents, such as pulsed power modulators and hard-switched power electronics.

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+ Improvements In The Modeling Of Wind Turbines In Power System Studies
  Nimmagadda, S; Islam, A; Bayne, SB; Sanchez, J; Caballero, LG
Abstract:  Several methods to improve the current wind turbine modeling techniques for power system studies are discussed in this paper. Some of the modeling improvements which are discussed are dynamic initialization of models, differences between wind turbine models developed in electromagnetic transient program and bulk power system simulation software, and techniques to avoid numerical instability with minimum errors. Algorithms to provide automatic initial conditions of all variables for any given load flow condition, wind speeds, and wind farm control strategies are developed in this paper. This approach is an improvement to the traditional method of providing constant initial values for given operating conditions. Several physical components such as harmonic filters, cable impedances, and complex control algorithms are either simplified or excluded in the power system models. The fault response of the power system model under extreme conditions leads to a numerically unstable condition. The instability might be a result of simplification discussed above and does not occur in the real turbine. Additional modeling techniques that can be used to achieve numerical stability, dynamic and fault response close to the actual wind turbine are discussed. These techniques are used to compensate for the simplifications made in power system models. Finally, the issue of nuisance tripping faced very frequently by the Independent System Operators, while working on the studies involving wind power plants, is addressed. Various methods to reduce the deviations and prevent nuisance tripping are implemented in the paper. (C) 2015 AIP Publishing LLC.
+ Offshore Wind Energy: A Comparative Analysis Of Uk, Usa And India
  Kota, S; Bayne, SB; Nimmagadda, S
Abstract:  Offshore wind is one of the most fascinating industries in the renewable energy sector and it is experiencing a remarkable growth. Offshore wind energy generation offers an opportunity in the race to decrease the dependence on fossil fuels, reduce green house emissions, increase energy security and create employment opportunities. UK has proven success in offshore wind and has been enjoying the economic benefits of offshore wind since over a decade. Offshore wind energy is an emergent renewable energy industry in the United States. The United States is coping up with the challenges and heading up fast to catch up with the industry. India is still in its infancy stage where the policy frameworks are framed by MNRE government and getting ready with the tools to enter into the offshore market. This paper researches the current situation and trend of offshore wind industries in UK and US, from aspects of policy, grid connections, operation and maintenance and cost reduction and analyses the proper direction and pathways of the industry to India. Therefore this paper highlights the scenario as to how these three countries UK, USA and India, respectively, are enabling offshore wind, to make a vital and sizeable contribution to the low carbon economy. (C) 2014 Elsevier Ltd. All rights reserved.
+ Overview Of Grid Connected Renewable Energy Based Battery Projects In Usa
  Subburaj, AS; Pushpakaran, BN; Bayne, SB
Abstract:  Reliable source of energy is a topic of momentous concern in the world due to the uncertainty in conventional energy sources. The situation gets exacerbated with the impact of natural disasters on the transmission grid. The advent of cutting edge energy storage technology has provided a competent solution. Energy storage system is an integral part of a grid since it enhances the stability and performance by disengaging the energy generation source and the load especially when intermittent renewable energy sources are a part of the system. Battery technology should not only be able to demonstrate high performance but must be economically viable for project implementation. Several grid connected renewable energy based battery projects have been implemented for research and development as well as commercial application. The projects discussed in this review are considered based on the availability of information. This review paper will focus on grid connected battery projects powered by wind and solar energy generation sources. (C) 2015 Elsevier Ltd. All rights reserved.
Publication Year:  2014
+ A Study Of Recent Changes In Southwest Power Pool And Electric Reliability Council Of Texas And Its Impact On The U.S. Wind Industry
  Nimmagadda, S; Islam, A; Bayne, SB; Walker, RP; Caballero, LG; Camanes, AF
Abstract:  Due to the increased penetration of renewable energy resources, there has been a lot of activity in the regional transmission organizations such as development of new standards, protocol revisions, new study requirements, changes to modeling procedures etc., in the last five years with a special focus given to wind energy. The key objective of this paper is to identify the impacts and the immediate technological and market related improvements required by the wind industry as a result of such changes in Southwest Power Pool (SPP) and the Electric Reliability Council of Texas (ERCOT). The paper documents the most important activities by following the higher-priority committees, work groups and task forces in both companies along with some of the special projects or initiatives such as sub-synchronous control interaction study, primary frequency response, hub concept and other modeling improvements related to wind energy. The paper provides an analysis of the impact of each change resulting in technology upgrades to wind turbines, modeling improvements by turbine manufacturers and policy/market changes affecting wind farm developers. Finally the paper provides recommendations regarding the requirements and capabilities which the future wind farms and wind turbines need to possess. (C) 2014 Elsevier Ltd. All rights reserved.
+ An Evaluation System For Experimental Silicon And Silicon Carbide Super Gate Turn Off Thyristors
  Bayne, S; Lacouture, S; Lawson, K; Giesselmann, M; Scozzie, CJ; O'Brien, H; Ogunniyi, AA
Abstract:  This paper describes the design and implementation of a small-scale pulsed power system specifically intended to evaluate the suitability of experimental silicon and silicon carbide high power Super Gate Turn Off thyristors for high action (500 A(2) s and above) pulsed power applications where energy is extracted from a storage element in a rapid and controlled manner. To this end, six of each type of device was placed in a controlled three phase rectifier circuit which was in turn connected to an aircraft ground power motor-generator set and subjected to testing protocols with varying power levels, while parameters such as offset firing angle were varied. (C) 2014 AIP Publishing LLC.
+ Evaluation Of Sic Jfet Performance During Repetitive Pulsed Switching Into An Unclamped Inductive Load
  B. N. Pushpakaran; M. Hinojosa; S. B. Bayne; V. Veliadis; D. Urciuoli; N. El-Hinnawy; P. Borodulin; S. Gupta; C. Scozzie
Abstract:  Silicon carbide (SiC) depletion mode junction field-effect transistors (JFETs) are well suited for pulsed power applications as an opening switch due to their normally ON (N-ON) nature. To assess the robustness and breakdown energy tolerance of JFETs under pulsed conditions, they must be evaluated for breakdown energy capability before failure. This is very important for circuit breaker applications due to the large voltage spikes induced during the opening of the circuit breaker while it still conducts substantial load current. These voltage spikes can drive the JFET into the breakdown voltage regime and may result in device failure if the energy dissipation is above the tolerance limit. To determine the maximum avalanche energy of the device under repetitive pulsed conditions, a N-ON SiC JFET with a nominal rating of 1200 V/13 A was driven into punchthrough breakdown using an unclamped inductive switching (UIS) circuit. The testing comprised of 4000 repetitive pulses at 25°C case temperature at a fixed gate voltage of -20 V. The drain current was increased after every 1000 pulses to increase the energy dissipated. The JFET was able to withstand 1000 pulses at a maximum energy dissipation value of 1160 mJ before failure. The JFET triode breakdown characteristics were analyzed after every 1000 pulses. The peak UIS energy of 1160 mJ corresponded to an energy density of 16.6 J/cm2 based on their active area.

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+ Fast Supercapacitors Based On Graphene-Bridged V2O3/Vox Core-Shell Nanostructure Electrodes With A Power Density Of 1 Mw Kg(-1)
  Pan, X; Ren, GF; Hoque, MNF; Bayne, S; Zhu, K; Fan, ZY
Abstract:  Transition metal oxides (TMOs), with their very large pseudocapacitance effect, hold promise for next generation high-energy-density electrochemical supercapacitors (ECs). However, the typical high resistivity of TMOs restricts the reported ECs to work at a low charge-discharge (C-D) rate of 0.1-1 V s(-1). Here, a novel vanadium oxides core/shell nanostructure-based electrode to overcome the resistivity challenge of TMOs for rapid pseudocapacitive EC design is reported. Quasi-metallic V2O3 nanocores are dispersed on graphene sheets for electrical connection of the whole structure, while a naturally formed amorphous VO2 and V2O5 (called as VOx here) thin shell around V2O3 nanocore acts as the active pseudocapacitive material. With such a graphene-bridged V2O3/VOx core-shell composite as electrode material, ECs with a C-D rate as high as 50 V s(-1) is demonstrated. This high rate was attributed to the largely enhanced conductivity of this unique structure and a possibly facile redox mechanism. Such an EC can provide 1000 kW kg(-1) power density at an energy density of 10 Wh kg(-1). At the critical 45 degrees phase angle, these ECs have a measured frequency of 114 Hz. All these indicate the graphene-bridged V2O3/VOx core-shell structure is promising for fast EC development.
+ Kilohertz Ultrafast Electrochemical Supercapacitors Based On Perpendicularly-Oriented Graphene Grown Inside Of Nickel Foam
  Ren, GF; Pan, X; Bayne, S; Fan, ZY
Abstract:  Ultrafast electrochemical supercapacitors (EC) that can work at or above kilohertz (kHz) frequency, 3-4 orders higher than traditional EC, call for a structure,with extremely low equivalent serial resistance (ESR) and a reasonably large surface area. Three-dimensional perpendicularly-oriented graphene (POG) network, grown inside of Ni foam (NF) by microwave plasma chemical vapor deposition, is reported as electrode to fabricate such ultrafast EC. The folded POG inside NF provides a large surface area, while the straight-forward and wide-open porous structure of POG ensures fast ion migration. In conjunction with the intrinsic high electronic conductivity of graphene and Ni, POG/NF electrode based ultrafast EC was demonstrated with a specific cell capacitance of 0.32 mF/cm(2) at 1 kHz, a relaxation time constant of 0.248 ms, and an ESR of 70 m Omega. A charge-discharge rate as high as 500 V/s was also measured, at which the cyclic voltammogram maintained a rectangular shape, corresponding to a single electrode capacitance of 0.83 mF/cm(2). (C) 2014 Elsevier Ltd. All rights reserved.
+ Safe Operating Area And Long-Term Reliability Of 9-Kv Silicon Carbide Pnpn Super Gate Turn-Off Thyristors
  K. Lawson; S. B. Bayne; S. Lacouture; L. Cheng; H. O"™Brien; A. Ogunniyi; C. Scozzie
Abstract:  One of the major requirements for adoption of new silicon carbide (SiC) super gate turn-off thyristors (SGTOs) into high-energy applications is to verify the safe operating area and long-term reliability capabilities of these devices. In this letter, we have developed a unique high-energy testing system that can evaluate the performance limitations with respect to lifetime capabilities of the 9 kV, 1 cm $^{2}$ , SGTOs at ultrahigh pulsed current levels from 1 to 3.5 kA. The test system produces square current pulses with a user specified current amplitude and a 100- $\mu $ s pulsewidth at a maximum repetition rate of 1 shot/s (>0.1% duty cycle). A lifetime safe operating area with respect to maximum pulsed current was then established that these 1 cm $^{2}$ , 9 kV, SiC SGTOs can perform reliably without significant degradation at pulsed current levels up to 2.0 kA. At current levels above 2.0 kA shifts in the on-state voltage are observed probably due to device over-heating at such high current levels and having not enough time to fully dissipate the heat between any two shots, which results in the device rapidly deteriorating due to increased on-state losses ultimately leading to premature failure.

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Publication Year:  2013
+ Automated Modular High Energy Evaluation System For Experimental Thyristor Devices
  Lacouture, S; Lawson, K; Bayne, S; Giesselmann, M; Scozzie, CJ; O'Brien, H; Ogunniyi, AA
Abstract:  A high energy, modular, completely automated test bed with integrated data acquisition and characterization systems was successfully designed in order to perform both safe operating area as well as very high volume reliability testing on experimental silicon carbide Super Gate Turn Off (SGTO) thyristors. Although the system follows a modular design philosophy, with each functional block acting as a peripheral to a main control module and can be adapted to arbitrary power and pulse width levels, for the specific SGTO devices initially evaluated it was configured to have the device discharge variable current levels of up to 6 kA into a 0.5 Omega resistive load with a relatively square pulse fixed at 100 mu s full width at half maximum delivering energy levels up to 1.8 kJ to the load. (C) 2013 AIP Publishing LLC.
+ High Temperature Unclamped Inductive Switching Mode Evaluation Of Sic Jfet
  B. N. Pushpakaran; M. Hinojosa; S. B. Bayne; V. Veliadis; D. Urciuoli; N. El-Hinnawy; P. Borodulin; S. Gupta; C. Scozzie
Abstract:  Silicon carbide (SiC) unipolar transistors are an efficient choice in the design of high temperature 1200 V switching power supplies and dc-dc converters. To reduce the form factor and increase the power density of the circuit, the switching frequency must be high. This intensifies the negative impact of parasitic inductance and results in high voltage spikes that can drive a switching device into breakdown, followed by rapid destruction. To study the device performance under unclamped inductive switching (UIS) conditions, a normally-ON 1200 V/13-A SiC junction field-effect transistor (JFET) is driven into punch through breakdown using a single pulse. The testing is performed using an UIS setup, in which energy initially stored in an inductor is discharged through the JFET. The testing comprises of 90 single pulses each at 25°C and 100 °C case temperatures for different gate voltages and drain current values. The peak energy and power dissipated in the JFET are 621 mJ and 16 kW, respectively, at the rated 1200 V blocking voltage and 13-A drain current. The JFET triode breakdown characteristics are unchanged after 180 single-pulse switching events indicating the robust nature of the device under extreme breakdown conditions. In addition, the 621 mJ peak UIS energy and its corresponding 8871 mJ/cm2 density dissipated in the JFET are the highest reported for any SiC power device.

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+ Reliable Operation Of Sic Jfet Subjected To Over 2.4 Million 1200-V/115-A Hard Switching Events At 150 Degrees C
  Veliadis, V; Steiner, B; Lawson, K; Bayne, SB; Urciuoli, D; Ha, HC; El-Hinnawy, N; Gupta, S; Borodulin, P; Howell, RS; Scozzie, C
Abstract:  A requirement for the commercialization of power SiC transistors is their long-term reliable operation under hard switching conditions and high temperatures encountered in the field. Normally ON 1200-V vertical-channel implanted-gate SiC JFETs, designed for high-power bidirectional (four-quadrant) solid-state circuit breaker applications, were repetitively pulsed hard switched at 150 degrees C from a 1200-V blocking state to an ON-state current of 115 A, which is in excess of 13 times the JFET's 250-W/cm(2) rated current at 150 degrees C. The JFETs were fabricated in seven photolithographic levels with a single masked ion implantation forming the p(+) gates and guard rings and with no epitaxial regrowth. The pulsed testing was performed using a low-inductance RLC circuit. In this circuit, the energy initially stored in a capacitor is discharged in a load resistor through the JFET under test. The JFET hard switch stressing included over 2.4 million 1200-V/115-A hard switch events at 150 degrees C and at a repetition rate of 10 Hz. The peak energies and powers dissipated by the JFET at each hard switch event were 73.2 mJ and 68.2 kW, respectively. The current rise rate was 166 A/mu s, and the pulse FWHM was 1.8 mu s. After over 2.4 million hard switch events at 150 degrees C, the JFET blocking voltage characteristics remained unchanged while the ON-state current conduction slightly improved, which indicate reliable operation.
Publication Year:  2012
+ Hard-Switch Stressing Of Vertical-Channel Implanted-Gate Sic Jfets
  Lawson, K; Alvarez, G; Bayne, SB; Veliadis, V; Ha, HC; Urciuoli, D; El-Hinnawy, N; Borodulin, P; Scozzie, C
Abstract:  A requirement for the commercialization of power SiC transistors is their long-term reliable operation under the hard-switching conditions encountered in the field. Normally ON 1200-V vertical-channel implanted-gate SiC JFETs, designed for high-power bidirectional (four-quadrant) solid-state-circuit-breaker applications, were repetitively hard switched from a 150-V blocking state to an ON-state current in excess of eight times the JFET's 250-W/cm(2) rated current. The JFETs were fabricated in seven photolithographic levels with a single masked ion implantation forming the p(+) gates and guard rings and no epitaxial regrowth. The hard-switch testing was performed using an RLC circuit capable of currents in excess of 200 A with a rise time of 150 A/mu s. In this circuit, energy initially stored in the capacitor is discharged to the resistor through the JFET under test. The JFET hard-switch stressing included 1000 shots at each temperature of 25 degrees C, 50 degrees C, 100 degrees C, and 150 degrees C and at each repetition rate of 1, 5, 10, and 100 Hz for a total of 16 000 shots. Peak energies and powers dissipated by the JFET were 7.5 mJ and 9 kW, respectively. JFET conduction and blocking-voltage characteristics remain unchanged after 16 000 pulsed hard-switching events, which is indicative of reliable operation and excellent JFET suitability for nondegrading repeated bidirectional high surge-current fault isolation.
Publication Year:  2011
+ Transient Performance Of Sic Mosfets As A Function Of Temperature
  K. Lawson; S. B. Bayne
Abstract:  This research was completed to study the effects of extreme transient conditions on Silicon Carbide MOSFET devices. Two different transient conditions that are common in power converters were studied in this paper. The first is effects of voltage rise time, or dV/dt, on these devices. The second is the effects of current pulses with short pulse width and high peak currents. Both of these tests were conducted at temperatures of 150 °C to determine the performance of these devices in high stress environments. For both of these experiments, testing apparatus had to be designed and built to create these specific conditions.

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Publication Year:  2007
+ An Experimental Approach For Thermal Characterization Of Water-Cooled Heat Sinks Using Fourier Analysis Techniques
  Salem, TE; Bayne, SB; Porschet, D
Abstract:  As power electronic applications continue to switch higher levels of voltage and current in smaller-sized component packages, the resulting increase in power density requires efficient thermal management. This paper compares the thermal performance for operating a metal-oxide-semiconductor field-effect transistor on a water-cooled pole-arrayed heat sink versus a novel water-cooled microchannel heat sink. Details are presented on an innovative technique using Fourier analysis techniques for determining the thermal capacitance modeling parameter for the heat sinks from experimental data.
+ Evaluation Of 4 Mm X 4 Mm Silicon Carbide Thyristors
  O'Brien, H; Shaheen, W; Bayne, SB
Abstract:  The U. S. Army Research Laboratory (ARL) is evaluating silicon carbide thyristors to determine the extent of silicon carbide capabilities as a possible replacement for silicon in future pulsed switching applications. Individual SiC die measuring 4 mm x 4 mm were pulsed at high temperatures and varying pulse widths. At 150 degrees C, these thyristors were switched in an RLC circuit up to 3.2 kA and repetitively pulsed at 2.6 kA and 5 Hz for greater than 14,000 pulses. A pulse forming network (PFN) was designed to increase the pulse width and the action seen by the SiC devices. At ambient temperature and a peak current of 2 kA, SiC thyristors were switched in the PFN at a 50% pulse width of 40 mu s and an action of 150 A(2)s. These devices were also pulsed at narrower pulse widths in pairs to look at their behavior in parallel. One pair reached a peak total current of 6.7 kA with current sharing as good as 51% / 49%. This paper includes further data on the three aforementioned test procedures, as well as analysis of the devices' failure points.
+ Evaluation Of Advanced Si And Sic Switching Components For Army Pulsed Power Applications
  H. O'Brien; W. Shaheen; R. L. Thomas; T. Crowley; S. B. Bayne; C. J. Scozzie
Abstract:  Super gate turn-off thyristors (SGTOs) implemented in both silicon (Si) and silicon carbide (SiC) semiconductors were investigated for high-voltage, high-current pulsed power applications. Modular 80 and 400 kA switches implemented in silicon (2.0-cm2 dies) and individual SiC switch die (0.16 cm2) were evaluated. The Si 80- and 400-kA switches were demonstrated (at ambient temperature) to provide rates of current rise (10%-90% peak current) and peak currents (145-mus width) of 24 kA/mus and 92 kA; and 40 kA/mus and 400 kA, respectively. The Si 80-kA switch was repetitively pulsed 1000 times with no significant performance degradation. The SiC switch die were demonstrated to provide specific rate of current rise and current density of 49 kA/mus/cm2 and 56.1 kA/cm2, which are at least 2.5 times greater than are possible in silicon pulse switches. The SiC switches were repetitively pulsed at 5 Hz up to 99 000 times without failure and were demonstrated to operate at case temperatures up to 150 degC

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Publication Year:  2005
+ Thermal And Electrical Evaluation Of Sic Gtos For Pulsed Power Applications
  Geil, BR; Bayne, SB; Ibitayo, D; Koebke, MG
Abstract:  For applications which require high peak current and fast rise time, silicon carbide (SiC) material is ideal because of its ability to tolerate high localized temperatures generated during switching. This research was performed to,investigate SiC devices for pulse power applications and to analyze the failure, of the devices. Seven 2 mm x 2 mm SiC gate turn-off thyristors (GTOs) manufactured by Cree, Inc., Durham, NC, were evaluated. The devices were tested at single shot and under repetitive stress using a ring-down capacitor discharge circuit. The current pulsewidth was 2 mu s with a peak current of 1.4 kA (current density of 94.6 kA/cm(2)) and a maximum di/dt of 2.36 kA/mu s. The maximum power dissipated within the devices was 240 kW. Thermal modeling of these devices was done using ANSYS to analyze the heating and cooling. A two-dimensional model was used that included the device package and bonding materials. The maximum amount of power dissipated was calculated from the 1000-A, 2-mu s pulse. No further power input was added to the model and the heat transfer was plotted on an exponential scale. It was found that heat applied to a 2-mu m-thick region of the fingers yielded a temperature greater than 800 degrees C in the device. It took 1.0E-(02) s for this heat to dissipate and for the device to return to 23 degrees C. The minimum and maximum stresses were found to be -2.83E+(09) Pa. and 4.06E(+08) Pa respectively.
Publication Year:  2002
+ Advanced Operational Techniques And Pn-Pn-Pn Structures For High-Power Silicon Carbide Gate Turn-Off Thyristors
  Shah, PB; Geil, BR; Ervin, ME; Griffin, TE; Bayne, SB; Jones, KA; Oldham, T
Abstract:  SiC GTO thyristors may soon be the best available choice for very high-power switching. At this time, we have developed new operational techniques, growth requirements and pn-pn-pn type structures to address the issues of high on-state voltage, poor turn-off gain, and inability to reach predicted breakover voltages. We present these findings using experimental measurements and numerical simulations.
+ Half-Bridge Inverter Using 4H-Sic Gate Turn-Off Thyristors
  Tipton, CW; Bayne, SB; Griffin, TE; Scozzie, CJ; Geil, B; Agarwal, AK; Richmond, J
Abstract:  This paper reports on the first demonstration of a half-bridge power inverter constructed from silicon carbide gate turn-off thyristors (GTOs) operated in the conventional GTO mode. This circuit was characterized with input bus voltages of up to 600 VDC and 2 A (peak current density of 540 A/cm(2)) with resistive loads using a pulse-width modulated switching frequency of 2 kHz. We discuss the implications of the thyristor's electrical characteristics and the circuit topology on the overall operation of the half-bridge circuit. This work has determined the conservative critical rate of rise value of the off-state voltage to be 200 V/mus in these devices.
+ Inductive Switching Of 4H-Sic Gate Turn-Off Thyristors
  Bayne, SB; Tipton, CW; Griffin, T; Scozzie, CJ; Geil, B; Agarwal, AK; Richmond, J
Abstract:  The high-temperature operation of a silicon carbide gate turn-off thyristor is evaluated for use in inductively loaded switching circuits. Compared to purely resistive load elements, inductive loads subject the switching de-ice to higher internal power dissipation. The ability of silicon carbide components to operate at elevated temperatures and high power dissipations are important factors for their use in future power conversion/control systems. In this work, a maximum current density of 540 A/cm(2) at 600 V was switched at a frequency of 2 kHz and at several case temperatures up to 150degreesC. The turn-off and turn-on characteristics of the thyristor are discussed.
Publication Year:  2001
+ Mos-Gated Thyristors (Mcts) For Repetitive High Power Switching
  Bayne, SB; Portnoy, WM; Hefner, AR
Abstract:  Certain applications for pulse power require narrow, high current pulses for their implementation. This work was performed to determine if MOS controlled thyristors (MCTs) could be used for these applications. The MCTs were tested as discharge switches in a low inductance circuit delivering 1 mus pulses at currents between roughly 3 kA and 11kA, single shot and repetitively at 1, 10, and 50 Hz, Although up to 9000 switching events could be obtained, all the devices failed at some combination of current and repetition rate, Failure was attributed to termperature increases caused by average power dissipated in the thyristor during the switching sequence, A simulation was performed to confirm that the temperature rise was sufficient to account for failure. Considerable heat sinking, and perhaps a better thermal package, would be required before the MCT could be considered for pulse power applications.

Conference Paper/Presentation

Publication Year:  2021
+ A Case Study For Connecting Bidirectional Pev Station For Reactive Power Support To The Gleamm Prototype Microgrid
  S. Daneshvardehnavi; C. A. Negri; K. E. K. Schmitt; S. Bayne; M. Giesselmann
Abstract:  This paper presents a control strategy for reactive power support using Plug-in Electric Vehicles (PEV) as a case study for the Global Laboratory for Energy Asset Management and Manufacturing (GLEAMM) microgrid. The control topology is divided into two levels with a dynamic limitation. This Electric Vehicle (EV) station Charger has a topology including a full-bridge AC-DC rectifier and a bidirectional half-bridge DC-DC converter. In the first level, a PQ and power control are used for the AC/DC inverter and DC/DC converters, receiving the set-points for active and reactive power from the upper level. The second level is a central controller that is used to manage the reactive power at the microgrid and to provide the necessary power setpoints for the PEV. A dynamic limitation strategy is proposed to maximize the reactive power support maintaining a reasonable amount of active power to charge the EV battery, considering the maximum limitation of the AC/DC inverter. To validate the effectiveness of the proposed control strategy, simulation results from a three-phase system are simulated in Matlab/Simulink environment.

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+ A Dynamic Load Control Strategy For An Efficient Building Demand Response
  K. E. K. Schmitt; I. Osman; R. Bhatta; M. Murshed; M. Chamana; S. Bayne
Abstract:  This paper proposes a computationally efficient building energy management algorithm for demand response that can serve as a grid-ancillary system. The controller aims to regulate flexible loads and intelligent switches, complying with the utility"™s request. The control algorithm dynamically optimizes the load"™s configuration of the building. This optimization is based on the required power consumption level and the resident"™s actual comfort constraints. Since the load-matrix considered by the proposed algorithm is computationally expensive, a novel region-selection approach is incorporated in the algorithm to make the strategy computationally efficient. The proposed algorithm is validated through OPAL-RT Real-Time Digital Simulation with Raspberry Pi. The test results show that the algorithm is capable of curtailing controllable loads during emergencies and outage scenarios to maintain an uninterrupted supply to the critical loads and respect the power limit request of the building.

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+ Hierarchical Operation Of Flexible Building Microgrids For Distributed Critical Loads Resiliency
  M. Chamana; K. Schmitt; R. Bhatta; I. Osman; S. Liyanage; M. Murshed; S. Bayne; J. MacFie
Abstract:  Community-scale microgrids play an essential role in serving critical loads during emergency conditions, involving the operation of breakers, tie-switches, distributed energy resources (DERs), and loads. Electric loads are primarily considered as lumped loads without many granular levels of controls. Flexible buildings offer the central microgrid management system an opportunity to shed multiple noncritical loads at granular levels by adopting Internet-of- Things (IoT) based controls. This work presents a novel bi-level optimal sequence of operations for managing the controllable devices in microgrids to serve loads, based on a priority scheme in community scale-scale microgrids. The proposed methodology is formulated as a mixed-integer linear programming (MILP) model and adapts to various operating conditions. The proposed method is validated through case studies that are performed on the Banshee microgrid benchmark model.

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+ High-Voltage Silicon Carbide Thyristors On N-Doped Epi For Pulsed Power
  H. O"™Brien; A. Ogunniyi; S. -H. Ryu; T. Tsoi; S. B. Bayne
Abstract:  The Army Research Laboratory (ARL) has funded the development of high-voltage silicon carbide (SiC) thyristors and diodes for pulsed power switching, culminating in the novel 1.0 cm2, 15-kV SiC thyristor with n-type doping in the drift layer. N-type thyristors have been predicted to achieve faster switching speeds and lower switching losses, but were only recently realized following the development of novel fabrication techniques. These devices are targeted to reduce volume and increase reliability of pulsed switches in high-energy systems. ARL and Texas Tech University characterized the first fabrication lot of these devices for high-voltage DC-blocking capability (<1 µA leakage at 15 kV), optimal turn-on controls (4 A gate pulse), and on-state resistance at high current densities (up to 3 kA/cm2). This paper presents recent analysis of the turn-on speed and dI/dt capability for low-kHz pulse repetition of the n-type SiC thyristors as compared to previously reported 15-kV p-doped SiC thyristors. The current through the n-thyristor peaks 50 ns earlier, reaches 10% higher amplitude, and has significantly faster dI/dt as compared to the similarly designed p-thyristor.

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+ Intrusion Detection From Synchrophasor Data Propagation Using Cyber Physical Platform
  V. Roy; S. S. Noureen; S. Atique; S. Bayne; M. Giesselmann
Abstract:  Some of the recent reports show that Power Grid is a target of attack and gradually the need for understanding the security of Grid network is getting a prime focus. The Department of Homeland Security has imposed focus on Cyber Threats on Power Grid in their "Cyber Security Strategy,2018" [1] . DHS has focused on innovations to manage risk attacks on Power System based national resources. Power Grid is a cyber physical system which consists of power flow and data transmission. The important part of a microgrid is the two-way power flow which makes the system complex on monitoring and control. In this paper, we have tried to study different types of attacks which change the data propagation of Synchrophasor, network communication interruption behavior and find the data propagation scenario due to attack. The focus of the paper is to develop a platform for Synchrophasor based data network attack study which is a part of Microgrid design. Different types of intrusion models were studied to observe change in Synchrophasor data pattern which will help for further prediction to improve Microgrid resiliency for different types of cyber-attack.

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+ Investigating The Effects Of Non-Linear Loads On Generator Sets
  J. A. Rodriguez; F. Salcedo; S. B. Bayne
Abstract:  Non-linear loads have become more prevalent due to the increasing use of power electronics for power conditioning and regulation. The current harmonics generated from non-linear loads can cause long-term effects on generator sets, such as the degradation of their lifetime due to higher operating temperatures and component failures due to high current transients. A testbed was developed to run a 3-kW military tactical generator set under non-linear loads. The 3-kW generator set includes a permanent magnet alternator (PMA) and a power electronic converter to deliver a 120VAC/240VAC output at 60 Hz. A range of non-linear loads was developed to create several load profiles for the generator set. The generator set was tested in four-hour and two-hour intervals for several weeks under different load profiles to stress its alternator and internal power electronics. In addition, several measurements were taken during testing, such as the output power, output voltage and current, and stator winding temperature. The collected data and testing suggest that the power electronics converter is more susceptible to the current harmonics than the PMA. These issues can result in premature failures and overall degradation of the lifetime of the generator set.

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+ Maximum Power Point Tracking Of Inductive Resonant Wireless Power Transfer Systems Using A Buck Converter On The Receiving Side To Mitigate The Effects Of Coil Misalignment
  A. V. Bilbao; S. B. Bayne
Abstract:  The purpose of this paper is to show the results obtained by performing maximum power transfer in inductive resonant wireless power transfer (WPT) systems. The research highlights the importance of power electronic systems on the receiving side of a WPT system. Before getting into the specifics of the research, a fundamental theoretical analysis about WPT systems is performed followed by an LTSpice simulation setup and results. The results presented show that power electronic DC/DC converters can be successfully used to increase the amount of wirelessly delivered power through impedance matching.

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+ Reliability Of Sic Mps Diodes Under Non-Repetitive Forward Surge Current
  T. Tsoi; B. Westmoreland; S. Bayne; S. Jadva
Abstract:  Silicon Carbide (SiC) Merged PiN-Schottky (MPS) diodes have the benefit of conduction modulation under high current events while achieving low forward voltage and zero reverse-recovery under normal operations. Thus, the SiC MPS diodes can sustain surge currents several times larger than their average current rating, avoiding oversizing components and resulting in a more compact power electronic device. Two SiC MPS diodes were evaluated using a non-repetitive surge current testbed that delivers a square current pulse of 800 A. Five devices from each group were subjected to a ten µs current pulse every 20 seconds. The first device from each group started at lower current levels and was increased until device degradation occurred. Subsequent devices were then tested at the highest current level until degradation. Both groups have sustained currents up to 2.5 times their rated surge current rating. These devices were subjected to several thousand pulses, and their electrical characteristics, such as forward IV and reverse blocking voltage, were measured between testing intervals. Device degradation was observed as the reverse-blocking voltage has significantly decreased from preliminary measurements, but no degradation of the forward-IV curve was observed. The collected data demonstrate the device"™s ability to operate under non-repetitive surge current events. Each device has sustained several hundred pulses above their rated surge current rating before any sign of degradation was detected. Device degradation becomes apparent when the leakage current increases as the MPS diode is blocking voltage. They eventually become prone to short-circuit failure due to a reduced reverse blocking voltage capability.

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+ Safe And Intelligent Wireless Power Transfer System
  D. Z. Graves; A. V. Bilbao; S. B. Bayne
Abstract:  The purpose of this paper is to show the results obtained from novel research performed in the area of inductive-resonant wireless power transfer (WPT) safety. Traditionally a communication link between the transmitter and receiver power electronic system is required to ensure that power is delivered only to a suitable target system. This research aims to eliminate the communication hardware required to increase the system"™s volumetric power density and mass. Machine learning is used to perform current waveform analysis to detect the receiver"™s signature and enhance system safety.

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+ Sic Gtos Thyristor For Long Term Reliability On Pulsed Power Application Test
  T. Tsoi; C. Whitworth; M. Kim; S. Bayne; H. O"™Brien; A. Ogunniyi
Abstract:  Silicon Carbide (SiC) is a wide-bandgap semiconductor with a wider bandgap, higher critical electric field, higher saturation velocity, and higher thermal conductivity than silicon, making it desirable for pulsed power applications. The n-type Gate Turn-off thyristor (nGTO) is a controllable solid-state switch with high blocking voltage and high current conduction capabilities. However, its device structure is challenging to develop using SiC. Wolfspeed has developed a 15.0 kV SiC nGTO that withstood peak current up to 1.0 kA. A testbed was developed to evaluate the long-term reliability of these SiC nGTOs. The pulser operates with a capacitor bank charged to 10.0 kV to deliver a 35.0 µs ring-down current waveform through the device. The SiC nGTOs were pulsed with a repetition rate of 0.5 Hz. It was observed that the device dissipated 700.0 J peak energy during pulsing. COMSOL Multiphysics simulated the SiC nGTO during a single pulsing event. The simulation models the thermal flow and current density in the nGTO. The thermal result shows the peak device temperature rising to 360.1 K after 17 µs into the pulsing event. The peak magnitude of current density reached 15 kA/cm2

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Publication Year:  2020
+ A Review On Reliability Of Microgrid
  S. Ramabhotla; S. B. Bayne
Abstract:  Microgrid is considered as the future power systems due to the demand in the power supply and also due to its capability of integrating with the renewable energy sources. Based on the demand and location, the microgrid operates independently in an islanded mode by disconnecting from the power grid. A microgrid improves the efficiency of power consumption, along with the reliability of the power quality and power supply. The reliability of the microgrid is an important aspect to improve for the efficient power quality and availability of the electricity. This paper provides a review on reliability of microgrid considering various techniques and methods. The paper discusses about the background and concept of microgrid, effect of reliability in power systems, different scenarios of reliability in microgrids. Also, the challenges and solutions are elaborated from the implementation of various optimization techniques for the microgrid systems.

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+ Large-Scale Adoption Of Self-Synchronized Universal Droop Controller-Based Inverters To Enable Ancillary Services For Different Modes Of Distribution System Operations
  L. Arce; M. Chamana; I. Osman; B. Ren; Q. -C. Zhong; S. Bayne
Abstract:  This work proposes the large-scale adoption of self-synchronized universal droop controller (SUDC)-based inverters to enable ancillary services for different modes of distribution system operations. The IEEE 123 bus system was modeled on a real-time simulator to study the performance of large-scale adoption of SUDC inverters in a distribution system. The resulting data collected shows that the voltage and the frequency were regulated within ranges, such as less than 5% for voltage and less than 0.5% for frequency, under different load variations and grid operations. Also, the black start was achieved within 0.4 s without any voltage overshoot. Through the simulation and validation on a small microgrid and the IEEE 123 bus distribution system, it can be concluded that the SUDC was successfully adopted to regulate the voltage and the frequency within the given ranges, and black start achieved within 1 s without voltage overshoot for different modes of distribution system operations.

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+ Time Series Forecasting Of Total Daily Solar Energy Generation: A Comparative Analysis Between Arima And Machine Learning Techniques
  S. Atique; S. Noureen; V. Roy; S. Bayne; J. Macfie
Abstract:  In this paper, the potential of machine learning based methods for time series forecasting of total daily solar energy generation has been explored. Firstly, the time series is modeled using the seasonal version of well known classical method auto regressive integrated moving average (ARIMA) and its performance is later compared to two other popular machine learning methods, support vector machine (SVM) and artificial neural network (ANN). The potential of machine learning based methods in this line of work is demonstrated by the superior performance of SVM. However, the reasons behind the low yield of ANN need to be inspected to enhance our understanding. In spite of SVM's relative success in prediction of solar generation, the overall accuracy still needs to be improved and the methods to achieve this objective should be researched in future.

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Publication Year:  2019
+ Analysis And Application Of Seasonal Arima Model In Energy Demand Forecasting: A Case Study Of Small Scale Agricultural Load
  S. Noureen; S. Atique; V. Roy; S. Bayne
Abstract:  This paper has presented the use of Auto Regressive Integrated Moving Average (ARIMA) method for forecasting of seasonal time series data. The dataset that has been used for modeling and forecasting is a small-scale agricultural load. ARIMA method can be applied only when the time series data is stationary. As seasonal variations make a time series non-stationary, this paper also presents analyses on testing stationarity and transforming non-stationarity into stationarity. Lastly, model has been developed with a specific selection of orders for autoregressive terms, moving average terms, differencing and seasonality and the forecasting performance has been tested and compared with the actual value. The results are encouraging, however there is scope of further research in refining the idea.

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+ Anomaly Detection In Cyber-Physical System Using Logistic Regression Analysis
  S. S. Noureen; S. B. Bayne; E. Shaffer; D. Porschet; M. Berman
Abstract:  The emerging smart grid, cyber-physical infrastructure, provides a steady, secure, and reliable power system over the current power grid. Synchrophasor systems, like Phasor Measurement Units (PMUs), are a key element of smart grids. They have the capability to measure time-coherent phasors of a grid. The key advantage of PMUs is the fast sampling rate that they provide over traditional Supervisory control and data acquisition (SCADA) systems which can be in the range of 30-120 samples/second. These higher sampling rates come at the cost of higher data quantities. Generating large amounts of data per day poses a challenge in making the most efficient use of information. In this paper, this problem has been addressed utilizing machine learning techniques, Logistic Regression Analysis, on PMU data. Identifying system anomalies in smart power grids is the primary focus of this paper. The standard IEEE 39 Bus system has been modified using the RT-LAB environment to generate faults and to produce synthetic synchrophasor data. Archived/offline mode data from a Phasor data concentrator (PDC) database is being used to train and test the algorithm. Additionally, the algorithm has been tested in real-time using an OPAL-RT digital real-time simulator.

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+ Course Development On Synchrophasor Applications At The Undergraduate And Graduate Levels
  M. Chamana; S. Bayne; A. Swift
Abstract:  Phasor Measurement Unit (PMU) design and application requires knowledge of various mathematical and electrical engineering fundamentals. The fundamental theories are covered in lower level courses offered at the undergraduate level in a typical electrical engineering and energy related curriculum. Furthermore, laboratory equipment/device based courses help students to improve their practical skills. Since students find experimental, product development and group work related courses more engaging, they are motivated to enroll in such courses. This paper summarizes a PMU design and application course suitable for electrical engineering/renewable energy undergraduate and graduate students. The paper is aimed towards helping course developers who plan to develop similar courses in the future.

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+ Design,Development And Experimental Setup Of A Pmu Network For Monitoring And Anomaly Detection
  V. Roy; S. Noureen; T. Atique; S. Bayne; M. Giesselmann; A. S. Subburaj; M. A. Harral
Abstract:  Introduction of Synchronized phasor measurement unit (PMU) in power system is a solution for monitoring system wide disturbances. PMUs provide precise information about a system's phasors such as magnitude and phase angle of sine waves of the system. PMU data is a valuable source when determining the post-mortem of a fault, or a system disturbance. It can be unveiled what time the system began to falter and exactly what instabilities the system experienced. Knowing the cause of such instabilities will allow enhancement of the current system protection system. This will help in minimizing risk, disruptions or total system collapse. PMUs are synchronized via global positioning system (GPS). For wide area monitoring (WAM), synchronization of the PMUs allows for interconnected systems to be monitored simultaneously, giving real time records. This paper explores the impact of PMU in modern power system, deployment strategies of PMU network around Texas Tech University, importance of PMU data collected from the network, correlation of events by data analysis and focus on how the time stamped information is valuable for grid stability. The ongoing smart architecture of grid will increase dependency and importance on PMU based network in future.

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+ Electrical Equivalent Model Of Vanadium Redox Flow Battery
  Y. R. Challapuram; G. M. Quintero; S. B. Bayne; A. S. Subburaj; M. A. Harral
Abstract:  Grid-scale energy storage systems have become popular for the growth of hybrid renewable power systems. Due to design flexibility, low manufacturing costs for large scale, indefinite lifetime and recyclable electrolytes Vanadium redox flow batteries (VRFBs) are a promising energy storage technology. In this paper, an electrical equivalent model of VRFB which is present in Distributed Asset Research Testing (DART) facility in Texas is proposed. The VRFB is connected to a 3.6kW resistive load. The effect of flow rate and pump power losses has been considered in modeling the VRFB. A control method for State of Charge (SOC) estimation is also proposed as it plays an important role in over-charge/ discharge of VRFB. The entire work is simulated in Matlab/Simulink environment and the results obtained prove the efficient operation of VRFB.

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+ Forecasting Of Total Daily Solar Energy Generation Using Arima: A Case Study
  S. Atique; S. Noureen; V. Roy; V. Subburaj; S. Bayne; J. Macfie
Abstract:  In this paper, a well known statistical modeling method named ARIMA has been used to forecast the total daily solar energy generated by a solar panel located in a research facility. The beauty of the ARIMA model lies in its simplicity and it can only be applied to stationary time series. So our time series data, which is seasonal and non-stationary, is transformed into a stationary one for applying the ARIMA model. The model is developed using sophisticated statistical techniques. The optimum model is chosen and validated using Akaike information criterion (AIC) and residual sum of squares (SSE). Error analysis is done to demonstrate the efficiency of the proposed method. The accuracy of the developed model can be further increased, which is subject to future research.

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+ Performance Comparison Of Commercial Gan Hemt Under Repetitive Overcurrent Operations
  J. A. Rodriguez; M. Kim; S. B. Bayne; H. O'Brien; A. Ogunniyi
Abstract:  Gallium nitride (GaN) high-electron-mobility transistors (HEMT) are of great interest for pulsed power applications due to their proven capabilities in RF applications. With further advances in GaN power semiconductors, there's an interest in the evaluation of their performance under repetitive overcurrent operation in power electronics applications beyond the manufacturer's prescribed operating parameters. A GaN HEMT from two different vendors were evaluated in a pulsed ring down testbed at 475 V with a peak current above 80 A over a repetition rate of 138 Hz. The testbed employed a temperature chamber to adjust the case temperature of the device during testing. The devices' electrical characteristics, such as transconductance, forward I-V curve and reverse blocking voltage were measured throughout testing and have not shown significant degradation. The collected data from these measurements allowed a comparison of the devices' performance and shows their ability to handle transient overcurrent conditions commonly found in power semiconductor device applications.

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+ V2G For Reliable Microgrid Operations: Voltage/Frequency Regulation With Virtual Inertia Emulation
  S. Dinkhah; C. A. Negri; M. He; S. B. Bayne
Abstract:  In this paper, we propose a stable electrical grid model, in which a home with a Photo-Voltaic (PV) system and Vehicle to Grid (V2G) capable Electric Vehicle (EV) can operate in both grid-connected and islanded modes. The model is used for studying load transients, power-sharing, and fault analysis. The implemented control system overcomes challenging situations such as load changing and transient conditions by managing the power of the battery and PV and regulating the voltage and frequency in the islanded mode. The Maximum Power Point Tracking (MPPT) is modified to include a feature for limiting the power in case of islanded mode and fully charged EV battery. Furthermore, the droop control and virtual inertia is utilized in a unified control manner. The model is implemented in MATLAB/Simulink and deployed to a real-time simulation by using an OPAL-RT simulator to validate the feasibility of the proposed model. The results for the real-time simulations are presented, showing the capabilities for voltage and frequency regulation of the controller, in load variations and fault condition.

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Publication Year:  2018
+ A Renewable Solution Approach For Center Pivot Irrigation System
  V. Roy; S. S. Noureen; S. Bayne; A. Bilbao; M. Giesselmann
Abstract:  In this present study a hybrid renewable energy system is proposed to optimize the load demand for Center Pivot Irrigation System for remote cultivation areas in Lubbock, Texas. The energy resources included in the study are solar photovoltaic and wind energy. For the ease of study, a 120-acre cultivable land area is considered as model. Simulation and analysis of the load is developed using HOMER (Hybrid Optimization Model for Electric Renewable) software and the optimum use of renewable resources is determined. A RT-LAB based model is also developed to determine real time analysis of center Pivot load. As the impact of wind is remarkable and solar irradiance is significant in Lubbock area, the wind turbine and solar photovoltaic system is given priority for effective optimization. Using HOMER software and RT-LAB based analysis of different combinations and multiple components are considered for simulation study. An optimal solution is proposed in the work by considering the renewable energy resources as prime sources in Lubbock area for this optimization method.

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+ Analysis Of Commercial Gan Hemts In Overcurrent Operation
  M. Kim; J. A. Rodriguez; W. B. Ray; S. B. Bayne; H. O"™Brien; A. Ogunniyi
Abstract:  Gallium nitride (GaN) high electron mobility transistors (HEMTs) are an ideal option in applications of power electronics due to the wide-bandgap properties of the material. High electron mobility is gained through the device's unique channel structure. This research investigates whether state-of-the-art GaN HEMT semiconductors are reliable in a long-term operation in high power switch-mode conditions. Information on overcurrent capability about GaN HEMTs is not well established, thus a demand to investigate the devices exists. The GaN HEMT GS66508P from GaN Systems, was tested in pulsed overcurrent operations to establish the performance and to observe any operational changes after the experiment. The device is rated at 650 V and 30 A continuous. The goal of this research is to see if the device characteristics change after overcurrent pulsing and to analyze the device degradation that occurs in higher energy density.

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+ Analysis Of Grid Connected Fuel Cell Power System Integrated With Supercapacitor
  N. Shamim; A. Bilbao; D. Reale; S. Bayne
Abstract:  This Paper analyses the integration of a super capacitor with fuel cell in grid connected mode. A super capacitor is a fast charging and discharging device. In a fault condition super capacitor will discharge and maintain the voltage of the DC bus. In this paper a mathematical model of the fuel cell power system is designed. A super capacitor and a grid are modeled in PSCAD simulation environment. The fuel cell power system is integrated with the grid using model predictive control technique. A fault is applied at the DC bus to study the impact of integrating a super capacitor with the fuel cell. The simulation results show the super capacitor can maintain the voltage at DC bus at fault condition.

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+ Charge Plasma High Voltage Pin Diode Investigation
  M. J. Kumar; S. Hahmady; R. Gale; S. Bayne
Abstract:  In this paper, we investigate the new approach on designing a high voltage PIN diode without introducing any doping into the silicon. The concept of charge plasma is basically using different metals with appropriate work-function as anode and cathode contacts, which cause the formation of "p" and "n" plasma regions in silicon respectively. We have used the Silvaco Atlas simulation to compare the forward and reverse I-V characteristics of the proposed device with the conventional PIN diode. Also, we looked at the temperature dependency of their reverse saturation current. We demonstrate that by using the charge plasma concept, the proposed CP-PIN diode and conventional PIN diode have identical characteristics.

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+ Event Detection From Pmu Generated Big Data Using R Programming
  V. Roy; S. S. Noureen; S. B. Bayne; A. Bilbao; M. Giesselmann
Abstract:  Recent advancement in Power System Analysis shows that implementation of PMU (Phasor Measurement Unit) in Smart Grid playing a significant role over SCADA. The main reasoning for that is more sampling data than traditional SCADA system. Every PMU data like voltage, current and Phase angle gives more samples in every second which is helpful for event detection. The enormous data send by each PMU in every second energies the big data issue. To find out and predict the transient situation and even small disturbances or anomalies from big data analysis within the specified short period of time is a challenge for near future. Because introduction of new smart electrical devices will boost up the big data issue. Processing of big data for post disturbance analysis is also an important task. This paper gives a scenario of PMU measurements received to PDC (Phasor Data Concentrator) from PMUs placed in distinct locations and detection of transient events for post disturbance analysis. In this analysis, the disturbances are evaluated with the R programming analysis and compare findings of chronological data from separate locations and also shows the relation between disturbances in a grid. For this analysis, the impacts of frequency and voltage data are also considered.

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+ Fuel Cell Power System Integration With Grid Using Finite Set Model Predictive Control Technique
  N. Shamim; G. M. Munoz; D. Reale; M. Harral; S. Bayne
Abstract:  This Paper evaluates the integration of fuel cell power system with the grid using finite control set model predictive controller. A mathematical model of the phosphoric acid fuel cell power system is designed. The grid and the fuel cell are modeled in PSCAD simulation environment. Direct power control technique for model predictive controller is used to control the converter. The steady state results are shown in the paper, Also, a single phase fault and three phase fault is applied at the grid side to study the effect of integrating the fuel cell with the grid. The simulation results show model predictive controller can effectively integrate fuel cell with the grid.

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+ Micro-Grid System Modeling Efforts Using Pq-Control For Single-Phase And Three-Phase Inverter
  G. M. Quintero; Y. Reddy Challapuram; A. Bilbao; S. B. Bayne; A. S. Subburaj; M. A. Harral
Abstract:  The integration of Microgrids (MGs) into the mains must be done with consideration of control techniques that ensure the appropriate synchronization and power balance between distributed generators (DGs) and the grid. This paper presents the development of a PQ-control model for the grid connected single-phase and three-phase inverters present in the Distributed Asset Research Testing (DART) facility in Lubbock, Texas. In a grid-tied configuration, the inverters will operate as a current source that inject current into the grid based on the established reference setting of active and reactive power. To achieve this operation, the inverter current must be monitored, and it will be subjected to abc to dq0 transformation (Clarke and Park transformation). In the case of a single-phase inverter, two orthogonal phase variables are required in order to perform the Park transformation (αβ-dq). A phase shift of 90° with respect to the real phase variable is introduced to get the beta component required to complete this transformation. By showing the power characteristics in simulations, the proposed control strategy will be illustrated. The entire work is performed in MATLAB/SIMULINK environment.

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+ Modeling Of Inverters For Fuel Cells For Grid-Tied And Islanding Mode With Smooth Transitions
  Giesselmann, M; Bayne, S; Shamin, N; Kelley, M; Reale, D; Cingoz, F
Abstract:  We are reporting on models for a group of inverters that can feed real and reactive power into a utility grid in Grid-Tied mode and is able to smoothly transition to islanded mode. In grid tied mode, the inverters are operating in P/Q mode and inject controllable amounts of real and reactive power into the grid. In islanded mode the inverters are grid forming and share power using droop control. We are presenting MatLAB-Simulink models and results of the simulations including the transitions.
+ Surge Current Analysis Of Commercial Off-The-Shelf 1200 V Silicon Carbide Jbs Diodes And Mosfet Body Diodes
  J. Forbes; F. Salcedo; C. Tchoupe-Nono; R. Gale; S. Bayne
Abstract:  As an increasing number of silicon carbide (SiC) power semiconductor devices become commercially available, and as silicon devices have reached their theoretical power density limits, SiC devices are being utilized in an increasing number of power electronics and pulsed power applications. A few examples of these applications include high-power DC-DC converters, inverters, motor drives, or high-voltage pulse generators such as a solid-state Marx generator. To encourage further adoption of SiC devices in these and other applications, further reliability testing and analysis must be conducted. One parameter that is important to study is the surge current capability of both SiC diodes and the body diodes of SiC MOSFETs. In this research, a surge current testbed was designed and built to test commercially available 1200 V / 10 A SiC JBS diodes from 3 different manufacturers, and the body diodes of 1200 V / 10 A SiC MOSFETs from 3 different manufacturers. The purpose of this work is to independently verify manufacturer datasheet claims regarding the surge current capabilities of their diodes. In addition, surge current ratings on the body diodes of the SiC MOSFETs are determined and published.

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Publication Year:  2017
+ An Overall Study Of A Real-Time Simulator And Application Of Rt-Lab Using Matlab Simpowersystems
  S. S. Noureen; V. Roy; S. B. Bayne
Abstract:  This paper summarizes the features and advantages of the renowned Real-Time Digital Simulator (RTDS) called OPAL-RT Simulator. Alongside with its applications in the electric power system for the system design, analysis and testing. This comprehensive study also includes a brief description of its software, hardware, I/O system, modeling, Hardware-in-the-Loop and other prospects. Tremendous advancement in the storage capacity and computational speed of the modern computer system has done for the last few decades. Assimilating this advancement, this simulation tool has designed with unique features like real-time model-in-the-loop, Hardware-in-the-loop. Also for moderate operational and maintenance cost, OPAL-RT Simulator has become more prevalent to the researcher. There are immense scopes of experimental research in power systems analysis. This is the prime reasoning for describing the necessity and significance of OPAL-RT simulator in this work. In addition, a semi-simulation experiment of a PV system is presented using RT-LAB software. Two of the most salient tools of OPAL-RT are 1) RT-LAB and 2) ARTEMIS, which were applied in power electronics are also summarized.

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+ Evaluation Of High Frequency Solid State Switches For Pulsed Power Applications Using A 12 Kw Variable Voltage Testbed
  Flack, T; Parson, J; Bittner, K; Driver, B; Zameroski, N; Bayne, S; Hettler, C
Abstract:  Field Effect Transistor (FET) controlled devices, such as MOSFETs and IGBTs, exhibit several desirable characteristics over other solid-state devices for pulsed power applications; benefits include high frequency switching, voltage control, and compact control circuitry. This paper details a testbed used for evaluation of the switching performance and characterization of FET controlled devices used in pulsed power systems as well as the diagnostics used to characterize the devices under test (DuT). The testbed presented in this research operates in two modes: (1) High energy pulsed mode, with charge voltages up to 300 V, pulse width of 3 seconds and up to 18 kJ total stored energy (2) Continuous pulse-train mode, with charge voltage up to 300 V, up to 18 kJ total stored energy and average current output up to 40 A. Both of these modes utilize a 396 mF capacitor bank to store energy. A fast, custom, gigabyte-memory-depth data acquisition oscilloscope records voltage and current waveforms at a 60 Mega-Sample/second rate. Due to the frequency regime (1-50 kHz), high current levels (up to 300 A peak) and wide voltage range of these experiments, making these measurements, reliably, is a non-trivial effort. Several methods of making each measurement were examined. Calibrated voltage, current, energy, and power waveforms quantify the DuT's turn-on / conduction / turn-off characteristics. Measurements of interest in these experiments are device current and device voltage; energy dissipated in the DuT is determined from these measurements.
+ Model Predictive Control Analysis For The Battery Energy Storage System
  N. Shamim; A. Subburaj; S. Bayne
Abstract:  This paper describes the Model Predictive Control technique for three phase bi-directional converter to integrate a battery system with the grid. The paper presents an overview of different predictive control technologies. The paper describes the basic concept, operating principle, governing equations and control algorithm of model predictive control for the power converter. The control technique is analyzed to integrate a 1MWh battery system model with the grid. The analysis is done in PSCAD simulation environment for both steady state and fault scenarios. The simulation results are presented to show the effectiveness of Model Predictive Control technology for battery integration.

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+ Narrow Pulse Evaluation Of 15 Kv Sic Mosfets And Igbts
  Hirsch, EA; Schrock, JA; Bayne, SB; O'Brien, H; Ogunniyi, A
Abstract:  With the progression of silicon carbide (SiC) technologies, single semiconductor switches with higher voltage and current capabilities are emerging. Evaluating the pulsed current capability of SiC semiconductor devices for pulsed power and power electronics applications is required to understand their performance and reliability. This paper presents the narrow pulse evaluation of 15 kV SiC MOSFETs (0.25 cm(2) active area) and IGBTs (0.32 cm(2) active area) with pulse widths in the range of 500 ns to 2 mu s. Testing results are presented with an 8 kV charge voltage and 50 A and 330 A peak conduction current for the MOSFET and IGBT, respectively. A fairly low inductance (< 500 nH) RLC circuit was used to generate the pulses and the device under test (DUT) was switched off during the pulse to create a trapezoidal type current waveform through the device. Transient characteristics, such as turn-on and turnoff times and energies, were measured to benchmark the devices(narrow pulse characteristics. The results presented in this paper demonstrate the characteristics of these devices for over-current narrow pulse applications.
+ Phasor Measurement Unit Integration: A Review On Optimal Pmu Placement Methods In Power System
  S. S. Noureen; V. Roy; S. B. Bayne
Abstract:  The Phasor Measurement Unit (PMU) is an imperative part for monitoring, protecting and controlling the current power system. For the current power systems, PMUs not only offer the synchronized measurements of real-time data of voltage but also the current and frequency. Placement of PMUs in each bus for monitoring the system is not feasible from economic point of view and also for big data handling. So it is an obligatory matter to reduce the number of PMUs in the bus system with the aim of attaining the maximum power system observation. Different techniques are being applied from past to present to solve this optimum PMU placement (OPP) problem such as heuristic method, mathematical programing. Heuristic method is a quick experience-based technique for solving the optimization problems. Various optimization methods for solving the OPP problems are being reviewed in this paper.

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+ Reconfigurable High Voltage Load For Pulsed Power Applications
  Kim, M; Forbes, JJ; Bilbao, AV; Schrock, JA; Bayne, SB
Abstract:  The evaluation of pulsed power systems and their constituent components requires unconventional loads with exceptional voltage, current, impulse energy, and continuous power dissipation capability. This paper presents the design and construction of a reconfigurable resistive load with active temperature monitoring for the evaluation of ultra-high voltage pulsed power modulators and semiconductor devices. The load consists of a network of 15 ceramic resistors (outer diameter of 2.54 cm and length of 30.48 cm) mounted vertically in an oil filled aluminum tank. To enable exceptionally high-power dissipation, the oil is pumped through the tank and through a radiator. A microcontroller based module activates a fan on the radiator if a preset oil temperature is surpassed. Experimental results gathered demonstrate that the load withstood 10 kW at 10 kV for 30 minutes, and that the temperature of the oil reached 80 degrees C.
+ Silvaco-Based Electrothermal Simulation Of 10 Kv 4H-Sic P-I-N Diode Under Pulsed Condition
  Pushpakaran, B; Bayne, S; Ogunniyi, A
Abstract:  The application of silicon carbide technology in p-i-n diode has facilitated the development of p-i-n rectifiers up to several kV blocking voltage with a much thinner drift region thickness as compared to its silicon counterpart. This research focuses on the 2D electrothermal simulation of a 10 kV 4H-SiC p-i-n diode model developed using Silvaco ATLAS software. The p-i-n diode structure was designed for 100 A/cm(2) forward current density with a cell pitch of 16 lam and an active area of 10 mu m(2). Physics based models were included to account for low-field mobility, carrier-carrier scattering, carrier generation recombination, avalanche breakdown, and lattice heating. The device model was simulated under steady state and transient conditions. Pulsed simulation of the p-i-n diode was carried out using an RLC ring down circuit to generate a 5 mu s wide pulse with peak current densities up to 5000 A/cm(2). The reverse recovery characteristics of the diode was analyzed for a forward current density of 100 A/cm(2) and varying turn-OFF dJ/dt to assess the limitation on usable switching frequency. Lattice temperature profile of the p-i-n diode was generated by including heat generation models during transient simulation to identify thermal hot spot formation and areas of possible failure during pulsed operation.
+ Silvaco-Based Evaluation Of 10 Kv 4H-Sic Mosfet As A Solid-State Switch In Narrow-Pulse Application
  Pushpakaran, B; Bayne, S; Ogunniyi, A
Abstract:  Key requirements for a solid state switch in a fast switching pulsed power circuit include high blocking voltage, high current conduction and fast switching capability. Typical pulsed power applications like plasma initiation and high-energy LASER require operating voltages in the order of several kilovolts. The development of a multi-kilovolt SiC MOSFET for fast switching pulsed power application would require detailed analysis of the device switching characteristics. Since the switching speed of a MOSFET is primarily dependent on the inter-electrode capacitances, it becomes critical to have a comprehensive understanding of the device capacitance and its effect on the gate driver requirements for narrow-pulse switching. In this research, 2D model of a 10 kV 4H-SiC MOSFET was developed using Silvaco ATLAS TCAD software and simulated for its steady state, AC, and transient characteristics. The device cell was designed for an active area of 5 mu m(2) and 100 A/cm(2) drain current density. The capacitance-voltage and gate charge curve for the SiC MOSFET were obtained via AC and transient simulation respectively. This data was used to estimate the gate drive requirements for the device under fast switching conditions.
+ Stability Analysis Of A.C. And D.C. Microgrids Using Opal-Real Time Digital Simulator
  A. Subburaj; A. R. Arra; S. Bayne
Abstract:  In recent years the significant improvementin micro grid technology has led to the utilization of thelocal distributed sources. The microgrids also have agreater role in the minimization of transmission losses. During power blackouts they serve as a main source ofpower for few emergency loads. It is common that usuallythe AC grids are preferred over DC grids to transmitpower over long distances in spite of various issuesassociated with AC grids such as frequency dip, voltagedrop due to reactance, charging currents, leakagecurrents, low power factor problems, skin effect andFerranti effect. One of the major reasons for suchpreference is that voltage can be easily stepped up orstepped down using transformers. Whereas in a DC gridsystem voltage conversion accounts for switching lossesand equipment costs. But at the micro grid level the supplyvoltages are low, and most of them are DC sources. Theenormous growth in the power semiconductor technologymakes it possible to convert voltages in DC with low costand reduced power losses. The AC and DC microgridmodels were developed in MATLAB/SIMULINKenvironment. The stability and transient analysis areperformed during faults and sudden load variations onboth the AC and DC microgrids in real time using OPALRTreal time digital simulator. The effects of stability on aweak grid scenario have been analyzed for both AC andDC microgrids.

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+ Wide Injection Range Ocvd System For Lifetime Spectroscopy Techniques
  S. Lacouture; J. Schrock; E. Hirsch; S. Bayne; H. O'Brien; A. A. Ogunniyi
Abstract:  To continually increase the voltage and current capabilities of power semiconductor devices, whether pushing older materials such as Si to its' intrinsic electrical limits or by employing newer substances like SiC or GaN, a thorough understanding of the entire device is required, from the basic physics of the material and its interactions with defects and passivation, up to the complete device structure, including terminal performance and device - level limitations. Of the fundamental parameters that affect device performance, the most complex and malleable is the carrier lifetime. Carrier lifetime has a profound effect on power devices designed for high voltage applications and power devices relying on conductivity modulation. This parameter cannot be given as a ball - park figure unlike mobility (and hence diffusion coefficients) as it is affected by nearly every processing step a device undergoes: a final device can have carrier lifetimes that differ drastically from the starting bulk material. The work herein utilizes a relatively new set of techniques collectively known as Lifetime Spectroscopy (LS) methods to extract fundamental material parameters relating to recombination activity: τη0, τρ0 and AEt. These LS methods directly measure recombination activity of defects and hence acquire characteristic data of defects and dopants that is complimentary in nature to the information gleaned about them from more orthodox methods such as Deep - Level Transient Spectroscopy (DLTS). The Open Circuit Voltage Decay (OCVD) method is used along with improved data manipulation algorithms to extract the effective carrier lifetime as injection and temperature are swept. A complete stand - alone system has been constructed that allows a very wide range of current injection (~1mA to > 200A) and built - in OCVD waveform acquisition. The first complete Temperature - Injection Dependent Lifetime Spectroscopy (T-IDLS) studies are carried out on a small signal PiN commercial diode.

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Publication Year:  2016
+ Analysis On Repetitive Pulsed Overcurrent Operation Of Gan Power Transistors
  W. B. Ray; M. Kim; A. Bilbao; J. A. Schrock; S. B. Bayne
Abstract:  Gallium Nitride (GaN) transistors are of great interest for pulsed power and high power applications due to the proven capability of Silicon Carbide (SiC) transistors. Due to recent advances in GaN power semiconductors, lateral GaN transistors need to be evaluated for their performance under repetitive pulsed overcurrent operation that can occur in power electronics or pulsed power applications. A normally-off GaN Systems GS61008P-E03-TY was evaluated in a pulsed ring down circuit at peak currents of up to 230 A over frequencies ranging from 0.5 to 20 Hz. Measurement of switching transient energy dissipation showed minimal difference over cumulative pulse history and pulse frequency. In addition, the device's electrical characteristics, including forward IV and transconductance, were measured throughout testing and revealed no significant degradation. These results demonstrate the GaN FET's robust ability to handle transient pulsed overcurrent conditions common for commercial power semiconductor device applications.

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+ Battery Connected Dfig Wind System Analysis For Strong/Weak Grid Scenarios
  A. S. Subburaja; N. Shamim; S. B. Bayne
Abstract:  The paper helps to understand the performance of the grid with battery and doubly-fed induction generator (DFIG) wind turbines when operating in a weak grid scenario with a low short circuit ratio (SCR). The concept will analyze the performance of the grid with battery connected DFIG both in steady state and transient scenario. The grid can be represented as a Thevenin equivalent circuit and is rated at 12.5 kV. A battery system and a wind system are connected at the point of common coupling (PCC). The battery system being modeled in PSCAD software is rated at 1 MW/1 MWh and the wind system model is rated at 2 MW. The grid has been characterized and analyzed based on two categories: strong grid and weak grid. A grid is considered to be weak when the flow of active and reactive power in the network causes a significant amount of voltage fluctuation at the point of common coupling. A grid is considered to be strong when the grid is stable with allowable nominal deviations with voltage and frequency. The strength of the grid can be measured by taking the ratio of grid's short circuit power with grid nominal power.

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+ Charge Transfer-Based Sensorless Voltage Feedback In Hv Capacitor Chargers
  A. V. Bilbao; M. G. Giesselmann; S. B. Bayne
Abstract:  Rapid capacitor chargers are typically used to charge a bank of capacitors with the purpose of discharging it into a pulsed power load [1,3]. Previous research shows that the charging voltage of the load can be accurately calculated in real-time using microcontroller software algorithms [1,5]. The objective of this paper is to report a hardware based approach to measure the charge transfer into the load capacitor and implicitly the capacitor charging voltage. The proposed circuit uses operational amplifiers in order to integrate the input charge. A microcontroller receives the integrated signal to compute the output voltage and stop the charging process when the target voltage has been reached. Failure to accurately detect the end of charge time could lead to an excessively large capacitor bank voltage. For this reason, the proposed method can be utilized as a primary means of end-of-charge detection in conjunction with a traditional voltage sensing scheme.

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+ Continuous Switching Of Ultra-High Voltage Silicon Carbide Mosfets
  A. V. Bilbao; J. A. Schrock; M. D. Kelley; E. Hirsch; W. B. Ray; S. B. Bayne; M. G. Giesselmann
Abstract:  Silicon carbide power semiconductor devices are capable of increasing the power density of power electronics systems [1, 2]. In recent years, devices rated to block voltages up to 20 kV have been demonstrated [3]. These research grade devices must be fully characterized to determine operating characteristics as well as failure mechanisms. The purpose of this paper is to demonstrate the continuous switching performance of ultra-high voltage metal oxide semiconductor field effect transistors (MOSFET) rated for 15 kV / 10 A. A high voltage boost converter was developed to evaluate the continuous switching performance where the high-voltage MOSFET is utilized as the main switching element. During operation, the on-state voltage, gate leakage current, and dc characteristics are monitored to determine device degradation. Measured device degradation is presented as a comparison of initial and final dc characterization.

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+ Evaluation Of Long Term Reliability And Safe Operating Area Of 15 Kv Sic Pin Diodes During Ultra-High Current Pulsed Conditions
  Hirsch, EA; Schrock, JA; Lacouture, S; Bilbao, A; Bayne, S; Giesselmann, M; O'Brien, H; Ogunniyi, A
Abstract:  Silicon Carbide (SiC) is a leading wide bandgap semiconductor for increasing the power density of high power applications. This paper overviews the long term reliability and safe operating area of 15 kV SiC PiN diodes during pulsed current conditions. An automated system is used to stress these devices with ultra-high current pulses and monitor degradation with in-system characterization. The system is capable of a 100 mu s full-width half maximum pulse width up to 15 kA, with a repetition rate of 0.5 Hz. Periodic in-system characterization measures device forward conduction and reverse breakdown. The devices in this paper are pulsed at current levels from 1.5 kA to 2.5 kA. Over 100,000 pulses at 1.5 kA have been performed with no degradation. The long term reliability and failure mode results for the 15 kV PiN diodes will be reviewed.
+ Operation And Maintenance Cost Optimization In The Grid Connected Mode Of Microgrid
  S. Ramabhotla; S. Bayne; M. Giesselmann
Abstract:  A microgrid integrated with Distributed Energy Resources (DERs), Energy Storage, and Controllable Loads along with critical and non-critical loads is considered. The operation and maintenance cost (O&M) optimization is performed by the Economic Dispatch using the Reduced Gradient Method in the grid connected mode of microgrid. The minimized cost function of the system must be obtained for the optimization of the O&M cost of microgrid while meeting the load demand. The O&M cost includes the operation and maintenance cost of generated energy by each source and also the energy purchased from the utility. For obtaining the minimum cost of the system, the reduced gradient algorithm is implemented. To improve the reliability and to enhance the economic dispatch operation, a diesel generator and a battery energy storage are included in the microgrid. Different scenarios of the energy sources are compared along with the change in wind and battery profiles of microgrid to obtain the minimum O&M cost of the system. Various profiles of battery and wind energy are considered and minimal O&M cost of each profile is obtained and compared. As a result, the optimal cost of the system is obtained by considering the change in wind and battery profiles and hence provides the optimal solution while meeting the critical and non-critical loads demand.

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+ Pulsed Power Evaluation And Simulation Of High Voltage 4H-Sic P-Type Sgtos
  A. Ogunniyi; H. O'Brien; M. Hinojosa; J. Schrock; S. Lacouture; E. Hirsch; S. Bayne; Sei-Hyung Ryu
Abstract:  Future Army pulsed power applications semiconductor devices that will meet requirements for high-power, low weight and volume, and fast switching speed. The following paper presents the pulsed power evaluation of high voltage silicon carbide (SiC) super gate turn-off (SGTO) thyristors. These devices are well suited for high voltage, high temperature pulsed power and continuous power electronic systems. A pulse-forming network (PFN) circuit and a low inductance, series resistor-capacitor (LRC) circuit were developed to evaluate both the fast dI/dt capability and the pulse safe operating area (SOA) of the SiC SGTO. Transient simulations of the high voltage SiC SGTOs were also performed on a narrow pulse LRC circuit to investigate the device's switching behavior under extreme pulsed conditions.

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+ Reliability Optimization Using Fault Tree Analysis In The Grid Connected Mode Of Microgrid
  S. Ramabhotla; S. Bayne; M. Giesselmann
Abstract:  In a microgrid, PTC Wind Solutions is used toimplement the optimization of reliability with the help of FaultTree Analysis (FTA). The reliability of each energy source alongwith the non-critical load is calculated. To interpret the faulttree results, the quantitative and qualitative analysis arecalculated. Then the importance measures like RiskAchievement Worth, Risk Reduction Worth, CriticalityImportance and Fussel -- Vesely Importance are used tocalculate the sensitivity and uncertainty of fault tree results. Thecomponents which are sensitive and at high risk are calculatedfrom the results. Using the logic gates in the PTC WindchillSolutions, the entire fault tree for a non-critical load outage isbuilt and studied. From the results, the unreliability andunavailability of the fault tree are used to calculate thereliability and availability of non-critical load outage. From theFault Tree Analysis, the unavailability and unreliability of noncriticalload outage are calculated which illustrates the values ofavailability and reliability. From the fault tree analysis, theunavailability and unreliability of non-critical load outage arecalculated as 0.01228, which illustrates that the availability andreliability as 98.77%. Minimal cut sets of circuit breaker acrossthe non-critical load, Point of Common Coupling at the maingrid, and a transformer are calculated from the QualitativeAnalysis. The top event probability evaluation of a non -- criticalload is performed using the Quantitative analysis whichindicates the system failure probability. The calculation ofImportance measures -- Risk Achievement Worth, RiskReduction Worth, Criticality Importance, Fussel -- VeselyImportance is performed. Thus, the reliability and availabilityof non-critical load is obtained using the PTC WindchillSolutions. The top event occurrence is caused by the basic andintermediate events of a fault trees. The components at high riskare calculated using the importance measures. Therefore, fromthe Qualitative and Quantitative analysis the components whichare at high risk and sensitive are obtained and maintained wellto optimize the reliability.

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+ Silvaco Based Electro-Thermal Analysis Of 4H-Sic Tiv-Jfet Structure Under Extremely High Current Density Resistive Switching
  B. N. Pushpakaran; S. B. Bayne; A. A. Ogunniyi
Abstract:  A 2D model of a 1200 V normally-ON 4H-SÄ°C Trenched and Implanted Vertical Junction Field Effect Transistor (TIV-JFET) cell structure was designed and simulated using Silvaco ATLAS TCAD software to investigate and understand the effects of extremely high current density pulsed switching on the device characteristics. The JFET cell was designed for an active area of 2 μm2 and a threshold voltage of -7 V. Physics-based models were included to account for impact ionization, recombination effects, band gap narrowing, mobility and lattice heating. The electro-thermal simulation was performed using a resistive switching circuit at an ambient lattice temperature of 300 K. The circuit was designed for an ON-state drain current density of 5000 A/cm2. The device was simulated using a 100 kHz 50% duty cycle gate signal consisting of four switching cycles considering the simulation duration bottleneck. The analysis of lattice temperature profile revealed the formation of thermal hot spot in the channel area close to the gate P+ regions in the JFET structure. Further analysis showed an increase in the minority carrier concentration in the vicinity of the gate implants which affected the switching characteristics of the JFET at extremely high current density.

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+ Simulation And Design Trade-Off Analysis Of 15 Kv Sic Sgto Thyristor During Extreme Pulsed Overcurrent Conditions
  J. A. Schrock; E. A. Hirsch; A. Bilbao; S. Lacouture; W. Ray; S. Bayne; M. Giesselmann; A. Ogunniyi; H. O'Brien
Abstract:  Silicon carbide Super Gate Turn-Off (SGTO) thyristors are an advanced technology for increasing the power density of high voltage pulsed power or power electronic systems. However, the transient characteristics and failure modes of these devices have to be further understood. This paper presents the Atlas TCAD simulation of a 15 kV SiC SGTO thyristor during extreme pulsed overcurrent conditions. The simulated device is first validated against dc measurements of a physical device. The device is then simulated at various pulse current amplitudes using a 10 stage 100 μs PFN. In addition, a tradeoff study for the drift region and anode mesa width is performed.

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+ Simulation Study Of Switching-Dependent Device Parameters Of High Voltage 4H-Sic Gtos
  A. Ogunniyi; J. Schröck; M. Hinojosa; H. O'Brien; A. Lelis; S. Bayne; S. Ryu
Abstract:  The silicon carbide (SiC) "Super" gate turn-off thyristor (SGTO) is a viable device for high voltage and fast dI/dt switching applications. These devices are well suited for various pulsed power applications requiring high peak currents in the kilo-amp regime. The turn-on transition speed is determined by the spreading velocity, which depends on applied gate current, applied anode current density, minority carrier lifetime, and both the gate base-width and the drift region of the thyristor. The impact of device parameters on switching performance is discussed in this work.

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Publication Year:  2015
+ Analysis Of Advanced 20 Kv / 20 A Silicon Carbide Power Insulated Gate Bipolar Transistor In Resistive And Inductive Switching Tests
  Bilbao, AV; Schrock, JA; Ray, WB; Kelley, MD; Bayne, SB
Abstract:  The power density of pulsed power systems can be increased with the utilization of silicon carbide power devices'. With the latest developments in manufacturing techniques, the fabrication of insulated gate bipolar transistor (IGBT) devices with blocking voltages as high as 20 kV are now possible(2). A complete practical understanding of ultra-high voltage silicon carbide device switching parameters is not yet known. The purpose of this research is to show switching parameters extracted from inductive and resistive switching tests performed on state of the art 20 kV silicon carbide IGBTs. Resistive switching tests were used to extract device rise time, fall time, turn-on delay, turn-off delay and conduction losses. Double pulsed inductive switching tests were used to extract turn-on and turn-off switching energies and peak power dissipation. The data was obtained at case temperatures from 25 degrees C to 150 degrees C.
+ Analysis Of Advanced 20 Kv/20 A Silicon Carbide Power Insulated Gate Bipolar Transistor In Resistive And Inductive Switching Tests
  A. V. Bilbao; J. A. Schrock; W. B. Ray; M. D. Kelley; S. B. Bayne
Abstract:  The power density of pulsed power systems can be increased with the utilization of silicon carbide power devices1. With the latest developments in manufacturing techniques, the fabrication of insulated gate bipolar transistor (IGBT) devices with blocking voltages as high as 20 kV are now possible2. A complete practical understanding of ultra-high voltage silicon carbide device switching parameters is not yet known. The purpose of this research is to show switching parameters extracted from inductive and resistive switching tests performed on state of the art 20 kV silicon carbide IGBTs. Resistive switching tests were used to extract device rise time, fall time, turn-on delay, turn-off delay and conduction losses. Double pulsed inductive switching tests were used to extract turn-on and turn-off switching energies and peak power dissipation. The data was obtained at case temperatures from 25 C to 150 C.

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+ Analysis Of Carrier Lifetime Effects On Hv Sic Pin Diodes At Elevated Pulsed Switching Conditions
  A. A. Ogunniyi; H. K. O'Brien; M. Hinojosa; L. Cheng; C. J. Scozzie; B. N. Pushpakaran; S. Lacouture; S. B. Bayne
Abstract:  Future Army power systems will require utilizing high-power and high-voltage SiC devices in order to meet size, weight, volume, and high power density for fast switching requirements at both component and system levels. This paper presents the modeling and simulation of a high voltage (>12kV) silicon carbide PiN diode for high action pulsed power applications. A model of a high power PiN diode was developed in the Silvaco Atlas software to better understand the extreme electrical stresses in the power diode when subjected to a high-current pulse. The impact of carrier lifetime on pulsed switching performance of silicon carbide (SiC) PiN diode was investigated.

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+ Analysis Of Gan Power Mosfet Exporsure To Pulsed Overcurrents
  W. B. Ray; J. A. Schrock; A. V. Bilbao; M. Kelley; S. Lacouture; E. Hirsch; S. B. Bayne
Abstract:  The advancement of wide bandgap semiconductor materials has led to the development of Gallium Nitride (GaN) power semiconductor devices, specifically GaN Power MOSFETs. GaN devices have improved characteristics in carrier mobility and on-state resistance compared to Silicon solid state switches. With the development of these new power semiconductor devices a need was established to understand the behavior of the devices switching performance under stress, with regards to situations in pulsing circuits. Through the examination of the switching characteristics of GaN devices, the results can be used for the improvement of advanced pulsing circuit design with GaN solid state switches. In this paper the authors develop a test bed to expose the GaN Power MOSFETs to single and repetitive pulsed overcurrents. The test bed was developed using a Pulse Ring Down board in a radially symmetric configuration to minimize the total equivalent inductance and resistance. The test bed switches the GaN MOSFET with low impedance between the DC bus and ground to induce the stress the MOSFET experiences during pulsed overcurrents. The DC characteristics were measured between switching sets to reveal characteristic signs of potential degradation and failure modes due to pulsed overcurrents. The single and repetitive pulse switching characteristics are captured, analyzed, and shown.

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+ Battery And Wind System In Weak/Strong Grid Analysis
  A. S. Subburaj; S. B. Bayne
Abstract:  The paper provides an analysis of the performance of the battery (1MW/1MWh) and wind system (1.7MW) when connected to weak or strong grid. Understanding the performance of the battery and analysis of the battery system tied to the distribution grid with heavy penetration of wind as a function of the strength of the grid is discussed with the aim to understand the optimized energy flow between the battery, the wind farm, and the utility grid, energy management for storage, battery performance, energy dispatch and reliability. The advanced battery model utilizes the dual polarization electrical equivalent model for the analysis. The grid-connected battery and wind system simulation results are obtained using PSCAD software.

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+ Development Of Secondary Breakdown Circuit For Dv/Dt Analysis Of Sic Devices
  Schrock, JA; Ray, WB; Bilbao, AV; Kelley, MD; Hirsch, EA; Holt, SL; Bayne, SB
Abstract:  Silicon carbide (4H-SiC) is a leading option for increasing the power density of pulsed power and power electronic systems(1, 2). SiC devices used in high voltage switching applications experience high dV/dt due to fast switching transients. Under high dV/dt conditions the devices can exhibit spurious turn-ON. For SiC devices to achieve widespread acceptance the dV/dt limit must be established. To measure the dV/dt limit, a circuit comprised of four silicon avalanche BJTs operating in secondary breakdown was constructed. This circuit is capable of generating dV/dts well in excess of what SiC unipolar and bipolar devices might be exposed to in typical applications. Two SiC diodes in an OR configuration are used to perform a comprehensive dV/dt analysis as a function of dc bias. Using this experimental setup dV/dts up to 200 V/ns were applied to SiC MOSFETs, and the induced gate to source voltage was measured. Preliminary dV/dt results achieved with the secondary breakdown circuit are shown for a range of dc biases.
+ Di/Dt Evaluation Of A Si N-Type Gto Designed For Pulsed Power Applications
  T. Flack; C. Hettler; S. Bayne
Abstract:  Pulsed power systems which utilize solid state switching devices, rather than spark/gas-type devices, could potentially exhibit increased energy density, repetition rate, operational lifetime, and ruggedness. However, further evaluation of advanced solid state devices, such as thyristor type devices, is required to better understand their operation for pulsed power applications. This paper details experimental evaluation of the dI/dt capabilities of a silicon (Si) n-type, asymmetric-blocking gate turn-off thyristor (GTO) manufactured by Silicon Power. The device under test (DUT) is rated to block up to 4 kV with rated dI/dt of 30 kA/μs. The DUT was designed as a solid state replacement for spark/gas-type switching devices in pulsed power applications. A low inductance test circuit was designed and built to evaluate the dI/dt capabilities of the DUT. Specific care was taken to minimize the parasitic inductance and thereby exploit the achievable dI/dt ratings by the test devices. An external fiber-driven gate driver is used to trigger the device with gate current (IG) of approximately 1.3 A and rate of current change (dIG/dt) of approximately 25.5 A/μs. Experimental dI/dt values greatly exceeded rated values; specifically dI/dt values of approximately 77 kA/μs were readily achieved at 4 kV. No device degradation was observed over the course of evaluation.

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+ Economic Analysis Of Battery Energy Storage System
  W. B. Ray; A. S. Subburaj; J. A. Schrock; S. B. Bayne
Abstract:  Grid-connected battery energy storage systems (BESS) are essential for improving the transient dynamics of the power grid. There is ongoing research about how BESS integration with renewable energy sources can improve renewable energy deployment in the grid. However, the economic feasibility of BESS is a practical limitation of their integration into power systems. BESS costs include both the start-up costs of building the system and the operating costs. Optimizing the operation of the BESS to maximize operating profit would make the BESS more economically feasible to power system operators, and lead to smoother integration of BESS. This manuscript overviews a program tool that analyses grid connected BESS in real world situations and optimizes the operation of the battery system. Through the use of this tool, a better understanding of the economic feasibility of BESS is achieved.

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+ Evaluation And Comparison Of 1200-V / 285-A Silicon Carbide Half-Bridge Mosfet Modules
  Kelley, MD; Bilbao, AV; Ray, WB; Schrock, JA; Bayne, SB
Abstract:  Silicon Carbide (4H-SiC) is a state-of-the-art solution for increasing the energy density of pulsed power and power electronics. High power SiC MOSFET modules have only recently become commercially available; for widespread acceptance further device characterization and reliability testing is necessary. The purpose of this work is to establish and compare device characteristics for two SiC power modules. Of the two modules tested, one contained Cree die and the other Rohm die. The device characteristics presented for the two modules are switching losses (E-ON & E-OFF) and on-state resistance (R-DS(ON)). E-ON, E-OFF, and R-DS(ON) were measured at 25 degrees C and 125 degrees C. The R-DS(ON) of the two modules was determined to be approximately equal; however, the SiC module containing the Cree die yielded significantly lower turn-on and turn-off switching losses. The measurements presented in this work demonstrate SiC power modules are a leading solution for high energy density applications.
+ Evaluation And Comparison Of 1200-V/285-A Silicon Carbide Half-Bridge Mosfet Modules
  M. D. Kelley; A. V. Bilbao; W. B. Ray; J. A. Schrock; S. B. Bayne
Abstract:  Silicon Carbide (4H-SiC) is a state-of-the-art solution for increasing the energy density of pulsed power and power electronics. High power SiC MOSFET modules have only recently become commercially available; for widespread acceptance further device characterization and reliability testing is necessary. The purpose of this work is to establish and compare device characteristics for two SiC power modules. Of the two modules tested, one contained Cree die and the other Rohm die. The device characteristics presented for the two modules are switching losses (EON & EOFF) and on-state resistance (RDS(ON)). EON, EOFF, and RDS(ON) were measured at 25°C and 125°C. The RDS(ON) of the two modules was determined to be approximately equal; however, the SiC module containing the Cree die yielded significantly lower turn-on and turn-off switching losses. The measurements presented in this work demonstrate SiC power modules are a leading solution for high energy density applications.

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+ Extraction Of Safe Operating Area And Long Term Reliability Of Experimental Silicon Carbide Super Gate Turn Off Thyristors
  Lacouture, S; Schrock, JA; Ray, WB; Hirsch, EA; Bayne, S; Giesselmann, M; O'Brien, H; Ogunniyi, A; Scozzie, C
Abstract:  While Silicon Carbide (SiC) based power switching elements are starting to appear that are able to perform better than their Si counterparts in terms of voltage hold off, current density and operating temperature, the material is still relatively new in the semiconductor arena, and although new device designs are simulated extensively before being committed to fabrication, there is often a large discrepancy between actual device performance and simulated results. Manufacturers certainly carry out some electrical testing of these quasi experimental components, but there is a dearth of information pertaining to Safe Operating Area (SOA) and device longevity. Texas Tech University's Center for Pulsed Power and Power Electronics, in cooperation with Army Research Lab, has carried out extensive long term, high - energy testing of SiC Super Gate Turn Off Thyristors (SGTOs) produced by Cree Inc. To conduct this extremely high volume testing at high energy levels, an automated test bed was designed that pulses the devices for an arbitrary number of cycles and alternately switches the device to a low energy characterization system, with all waveforms and current - voltage characteristics recorded. Approximately 350,000 high energy cycles on various SGTOs have been recorded. From this large database of results, actual SOA at high cycle count (>> 10,000 pulses) has been extracted for the devices. With each cycle's waveforms recorded, and the devices' characteristics traced at chosen intervals, several distinct changes in these parameters have been found to inevitably herald the imminent failure of a device. The most common change is in the gate - anode junction, where curve traces show a leaking, almost resistive behavior immediately before the junction becomes forward biased. As the system is completely automated, and limits can be set to halt a test sequence upon being broached, several devices have been brought to the brink of failure - an event that is usually catastrophic, physically destroying the device - to be examined by the manufacturer.
+ Fast And Accurate Electro-Thermal Behavioral Model Of A Commercial Sic 1200V, 80 M Omega Power Mosfet
  Pushpakaran, BN; Bayne, SB; Wang, GY; Mookken, J
Abstract:  The superior electro-thermal properties of Silicon Carbide (SiC) as compared to silicon make them a viable candidate for high voltage and high frequency applications. Due to the relatively recent surge in commercially available SiC power MOSFETs, there is an immediate demand for accurate simulations models to predict device behavior and aid circuit design process. This paper discusses the development of an accurate SPICE based model for a commercially available 1200V, 20A SiC power MOSFET manufactured by CREE Inc. based on the Enz - Krummenacher - Vittoz (EKV) MOSFET model. The advantage of using EKV model over the simplified quadratic model is the ability to characterize MOSFET behavior over weak, moderate and strong inversion regions with a single equation. The model was developed using parameters extracted through experimental data conducted at wide temperature range. Package parasitic components have been incorporated into the model to predict device behavior in high frequency switching applications. The model was simulated for its static and transient behavior and compared with actual device results to determine accuracy over a wide operating range.
+ Fast And Accurate Electro-Thermal Behavioral Model Of A Commercial Sic 1200V, 80 Mî© Power Mosfet
  B. N. Pushpakaran; S. B. Bayne; G. Wang; J. Mookken
Abstract:  The superior electro-thermal properties of Silicon Carbide (SiC) as compared to silicon make them a viable candidate for high voltage and high frequency applications. Due to the relatively recent surge in commercially available SiC power MOSFETs, there is an immediate demand for accurate simulations models to predict device behavior and aid circuit design process. This paper discusses the development of an accurate SPICE based model for a commercially available 1200V, 20A SiC power MOSFET manufactured by CREE Inc. based on the Enz - Krummenacher - Vittoz (EKV) MOSFET model. The advantage of using EKV model over the simplified quadratic model is the ability to characterize MOSFET behavior over weak, moderate and strong inversion regions with a single equation. The model was developed using parameters extracted through experimental data conducted at wide temperature range. Package parasitic components have been incorporated into the model to predict device behavior in high frequency switching applications. The model was simulated for its static and transient behavior and compared with actual device results to determine accuracy over a wide operating range.

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+ Physics Based Electro-Thermal Transient Simulation Of 4H-Sic Jbs Diode Using Silvaco Atlas
  B. N. Pushpakaran; S. B. Bayne; A. A. Ogunniyi
Abstract:  The unique design of Silicon Carbide (SiC) Junction Barrier Schottky (JBS) diode has proved its superiority over silicon in the field of high energy density pulsed power applications. JBS diode design enables the development of high blocking voltage silicon carbide rectifiers with low ON-state voltage drop, low leakage and negligible reverse recovery. In pulsed power applications, devices get driven above their rated current carrying capacity for a transient duration. Under this scenario, it becomes critical to have a thorough understanding of the electro-thermal behavior of the device under pulsed condition. This research focuses on the design and simulation of a 4H-SiC JBS diode structure in Silvaco ATLAS software under steady state and pulsed conditions. Physics based models were incorporated to account for drift diffusion process, mobility, impact ionization and lattice heating. The JBS diode was designed for a blocking voltage of 3.3 kV and an ON-state current density of 100 A/cm2. A schottky barrier height of 1.1 eV was selected for the device. An array of interdigitated P+ regions with optimized separation was designed to shield the schottky interface from the high blocking electric field without affecting the ON state characteristics. The simulation results were used to analyze breakdown electric field distribution, forward current conduction path, switching performance and areas of localized lattice heating. The diode structure was simulated under pulsed condition pertaining to 500 A/cm2 current density and the lattice temperature profile was analyzed to identify the formation of thermal hot spots in the device lattice and possible failure mechanism. The JBS diode structure was simulated for its reverse recovery at varying magnitudes of turn OFF di/dt for an ON-state current density of 100 A/cm2.

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+ Subsynchronous Oscillation Detection Using Phasor Measurements And Synchrosqueezing Transform
  M. He; S. Nimmagadda; S. Bayne; M. Giesselmann
Abstract:  In this paper, a novel scheme for subsynchronous oscillation detection and modal parameter estimation is proposed, by leveraging the rich information contained in high-rate phasor measurements as well as the effectiveness of synchrosqueezing transform for multimodal signal analysis. Specifically, an instantaneous time-frequency representation of a voltage/current signal is first obtained by applying synchrosqueezing transform to the real-time data collected by a phasor measurement unit. The non-zero synchrosqueezing transform coefficients quantify the undamped frequency components of the original voltage/current signal at each time instant. For an unknown number of undamped frequency components, unsupervised clustering is applied to the non-zero synchrosqueezing transform coefficients in the frequency domain, so as to determine how many modes comprise the signal, as well as which mode each non-zero synchrosqueezing transform coefficient belongs to. Then, for each detected mode, the corresponding non-zero synchrosqueezing transform coefficients are utilized to reconstruct a component of the original voltage/current signal. Finally, the magnitude, damping factor and phase angle of each mode are estimated by applying a least square estimation algorithm to the reconstructed component signal. The effectiveness of the proposed approach is revealed through several case studies using IEEE benchmark models. Further, practical issues involving missing data, measurement noise and transform basis functions are also systematically addressed in this study.

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+ Suitability Of N-On Recessed Implanted Gate Vertical-Channel Sic Jfets For Optically Triggered 1200 V Solid-State-Circuit-Breakers
  Veliadis, V; Steiner, B; Lawson, K; Bayne, SB; Urciuoli, D; Ha, HC
Abstract:  A requirement for the commercialization of power SiC transistors is their long term reliable operation under the hard switching conditions and high temperatures encountered in the field. Normally-ON 1200 V vertical-channel implanted-gate SiC JFETs, designed for high-power bidirectional (four quadrant) solid-state-circuit-breaker applications, were repetitively pulse hard switched at 150 degrees C from a 1200 V blocking state to an on-state current of 115 A, which is in excess of 13 times the JFET's 250-W/cm(2) rated current at 150 degrees C. The JFETs were fabricated in seven photolithographic levels with a single masked ion-implantation forming the p+ gates and guard rings, and with no epitaxial regrowth. The pulsed testing was performed using a low inductance RLC circuit. In this circuit, energy initially stored in a capacitor is discharged in a load resistor through the JFET under test. The JFET hard-switch stressing included over 2.4 million 1200-W115-A hard-switch events at 150 degrees C and at a repetition rate of 10 Hz. The peak energies and powers dissipated by the JFET at each hard-switch event were 73.2 mJ and 68.2 kW, respectively. The current rise rate was 166 Alps and the pulse FWHM was 1.8 mu s. After over 2.4 million hard-switch events at 150 degrees C, the JFET blocking voltage characteristics remained unchanged while the on-state conduction slightly improved, which indicate reliable operation. An optically triggered solid-state-circuit-breaker, based on these rugged JFET, is proposed.
+ Zero Voltage Switching Multi Resonant Converter Using 0.6µm Technology
  A. Mishra; S. B. Bayne; Changzhi Li
Abstract:  Technology used for high performance DC-DC voltage regulator based Integrated Circuits is evolving. Zero voltage switching buck converter is one such DC-DC regulation schemes integrated in the power conversion circuitry and is designed such that power density is maximized and the switching losses are reduced. This paper discusses the design of AMI06 technology based zero voltage switching buck converter operating at 1 MHz switching frequency. A design example accommodating input voltage range from 5V"“8V DC at a constant DC output voltage of 3V was considered. The simulations were performed on Cadence tool to verify the feasibility of the proposed converter. Finally this zero voltage switching buck converter is compared to the conventional buck converter in terms of switching losses and efficiency.

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Publication Year:  2014
+ Analysis And Review Of Grid Connected Battery In Wind Applications
  A. S. Subburaj; P. Kondur; S. B. Bayne; M. G. Giesselmann; M. A. Harral
Abstract:  This paper provides an overview of battery technologies and the grid-connected battery projects that integrate wind. It also discusses the deployment of a battery system at Reese Technology Center (RTC) in Texas. The research at RTC involves deploying energy storage devices (i.e. Batteries with grid-tie inverters) for application in wind farms to understand the interaction between wind energy, the grid and the grid loads. The research work focus on the modeling of a battery system and wind turbines when it is connected to the grid, with the aim to understand the optimized energy flow between the battery, the wind farm, and the utility grid, energy management for storage, battery performance, energy dispatch and reliability. With the view of modeling the test bed of the grid-connected battery project at Reese, this paper provides the preliminary simulation results using PSCAD on discharge characteristics of a single cell of a battery at various C rates.

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+ Analysis Of Dual Polarization Battery Model For Grid Applications
  A. S. Subburaj; S. B. Bayne
Abstract:  With worldwide growth of battery technologies in renewable energy production, the selection of battery model has become an important factor for a Battery Energy Storage System (BESS) to be deployed in a grid environment. It is essential to understand the battery type and the model, to achieve a coordinated control of the performance of BESS, Renewable Energy Sources (RES) and load management, including battery applications such as ramp control, frequency response, voltage response, emergency backup, transmission and distribution capacity utilization and peak load leveling, when connected to the grid. Recent studies showed that the battery capacity utilization is based on the battery discharge characteristics. In this paper, two types of battery models such as `stacked cell model' and `single cell model' of a 1 MWh Lithium Manganese Oxide (LMO) battery are taken into consideration to study the discharge characteristics. The approach is based on the use of the Dual Polarization Model (one of the Electrical Equivalent Circuit Models also called as Two Time Constant Model) in building the above mentioned battery models. The purpose of this paper is to build and simulate the battery models in Power Systems Computer Aided Design (PSCAD). Also the battery models are compared and analyzed on their performance during faults when connected to the resistive load at 1C discharge rate. The `single cell model' is constructed using the electrical equivalent circuit to build the 1 MWh battery module. In an attempt to simulate the `stacked cell model', initially one cell of the battery rated at 4.12 V, 60 Ah is modeled in PSCAD and then the cells are connected in series and parallel to build the model of 1 MWh battery module. The key results include the modeling of single cell and stacked cell models of the 1 MWh battery. The discharge characteristics of the battery models rated at 960V, 1200 Ah will be analyzed for the faults applied near the resistive load. The models will be tested for node compatibility, compilation issues and the response effectiveness when connected to the resistive load. Thus, the research paper will perform a comparative analysis of the simulation results of the two battery models in terms of discharge characteristics, speed, performance, stability and compatibility.

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+ Analysis Of Equivalent Circuit Of The Battery Connected To The Grid
  A. S. Subburaj; S. B. Bayne; M. G. Giesselmann; M. A. Harral
Abstract:  This paper provides an analysis of the equivalent circuit of the 1 MW battery tied to the grid. It also discusses the installation of a 1 MWh battery system at Reese Technology Center (RTC) in Lubbock, Texas. The research involves deploying energy storage devices for application in wind farms to understand the interaction between wind energy, the grid and the grid loads. A 1 MW/1 MWh battery storage system at the RTC is connected to the South Plains Electric Cooperative (SPEC) grid. The batteries are used for energy storage and for mitigation of transient conditions grid dynamics. In this paper the 1 MW battery is modeled in PSCAD and analyzed for its discharge characteristics when it is tied to the grid.

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+ Comparison Study Of The Controllers For Grid Connected Battery System
  A. S. Subburaj; W. B. Ray; S. B. Bayne
Abstract:  This paper performs a comparison study on the performance of operation of a battery connected grid system with bi-directional grid-connected inverter and conventional PQ controller in steady state conditions. The deployment of a 1 MWh battery energy storage system (BESS) at Reese Technology Center (RTC) in Lubbock, Texas is described. The battery energy storage device was installed to further understand the interaction and performance of the battery within the power grid with the existing wind turbines at RTC as well as renewable energy sources and grid loads. The paper shows the simulation results obtained from PSCAD with the design of the different controllers. Compared with conventional PQ controllers, the bi-directional converter controllers greatly enhance the grid-connected converter's performance in the aspects of reduced power oscillations and increased operating stability.

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+ Economic Dispatch Optimization Of Microgrid In Islanded Mode
  S. Ramabhotla; S. Bayne; M. Giesselmann
Abstract:  Microgrid combines with Distributed Energy Resources (DERs), energy storage, and controllable loads. It is connected to the maingrid through the point of common coupling (PCC). Economic dispatch using reduced gradient method is implemented for the optimization of energy in the microgrid using MATLAB. The optimization is obtained by minimizing the cost function of the system while meeting the load demand. The operation & maintenance cost, and investment costs are considered in the cost functions of the microsources. The minimum total cost of the system is obtained by comparing different scenarios of the microsources in the microgrid.

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+ Evaluation Of High-Voltage, High-Power 4H-Sic Insulated-Gate Bipolar Transistors
  M. Hinojosa; A. Ogunniyi; H. O'Brien; S. B. Bayne; C. Scozzie
Abstract:  This paper presents preliminary results on the static and dynamic characterization of 12 kV and 20 kV N-channel silicon carbide Insulated-Gate Bipolar Transistors (IGBTs). These state-of-the-art devices were evaluated for their possible use in pulsed-power and energy conversion applications. The 12 kV IGBTs had a chip area of 0.7 cm2 and were rated for 10 A. Their active area was 0.32 cm2, with a drift region of 140 μm and two different field-stop buffers of 5 μm and 2 μm. The 20 kV IGBTs had a chip area of 1 cm2 and were rated for 12 A. Their active area was 0.37 cm2, with a drift region of 180 μm, and their FSB was 2 μm. The switching and conduction losses were calculated for both devices with short pulses and low-inductance resistive loads. Both types of IGBTs displayed promising results for possible replacement of gas switches and Si IGBTs in high voltage applications.

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+ Large Chip Area Sic Pin Diodes Demonstrated For Thyristor Protection In A Pulsed System
  H. K. O'Brien; W. Shaheen; A. Ogunniyi; C. Scozzie; L. Cheng; M. Hinojosa; K. Lawson; S. Lacouture; S. Bayne
Abstract:  Asymmetric thyristors require protection from voltage and current reversals in high-inductance capacitor discharge systems. Silicon carbide (SiC) PiN diodes capable of blocking up to 16 kV were demonstrated to have the high-current capability to transmit forward pulse current in a series configuration with a thyristor, and to clamp reverse current in an anti-parallel configuration. In series with a thyristor, diodes were switched 1000 pulses at a single-shot rate at 2000 A peak current (3.8 kA/cm2 over anode area and 2100 A2s per pulse) without any notable increases in forward voltage or reverse leakage current. In the reverse clamp configuration, a parallel pair of PiN diodes was demonstrated to block 12 kV charge on the capacitor bank, then clamp a total of 4200 A current reversal with good parallel current sharing. These evaluations demonstrate that for high current density pulsing above 10 kV, individual 16 kV PiN diodes yield lower on-state voltage loss (16 V at 2000 A) than series-stacked assemblies of 9 kV SiC PiN diodes or 6 kV Si diodes.

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+ Modular Marx Generator For Dv/Dt Testing Of Power Semiconductor Devices
  W. B. Ray; J. A. Schrock; K. Lawson; S. B. Bayne
Abstract:  A solid-state modular Marx Generator was designed for the purpose of testing the dV/dt capability of Power Semiconductor devices. The Marx Generator is capable of producing up to 1 kV voltage transients with rise times on the order of 10-nanoseconds. This capability to do variable voltage amplitude leads to customizable dV/dt tests. The solid-state modular design will be covered in detail within the paper. The solid-state construction allows for this adjustable dV/dt rating through the utilization of multiple modular stages of Power MOSFETs. These Power MOSFETs have a lower voltage blocking ability, but faster switch closing times. The different modules are controlled through the use of fiber-optic links. These links signal the floating Gate Driver circuitry to synchronize their switch closing time. The floating Gate Driver utilizes isolated switch-mode DC-DC converters to supply the power needed to charge the MOSFET gates, from one ground-referenced power source. The Marx Generator uses high voltage Silicon Carbide Schottky Diodes for the voltage blocking elements when the individual modular stages trigger. The lack of reverse recovery for these high voltage SiC Diodes enables the fast voltage transients that are requisite for dV/dt ranges needed to test Power Semiconductor devices.

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+ Ruggedness Evaluation Of 56Mm(2), 180 A Sic Dmosfets As A Function Of Pulse Repetition Rate For High Power Applications
  Lawson, K; Schrock, J; Ray, W; Bayne, S; Cheng, L; Palmour, J; Allen, S
Abstract:  Modern power electronics systems try to maximize power density and efficiency. As such, the active switch is required to safely handle very stressful transient conditions. A 56 mm(2), 180 A, SiC DMOSFET manufactured by Cree Inc. is evaluated by electrically stressing the device in a RLC ringdown test system capable of producing peak current in excess of 600 A (> 3X rated current) and di/dt's as high as 860 A/mu s. The device was hard-switched 5,000 times at repetition rates of 1, 2, 5, and 10 Hz for a total of 20,000 switching events. The device characteristics were monitored every 1,000 shots on a high power curve tracer to determine device degradation. The devices showed no changes in blocking characteristics and minimal changes in on-state characteristics due to shifts in the threshold voltage after 20,000 hard switching events. The threshold voltage shifts over the test period are minimal with a +/- 93 mV deviation from the average of 4.39 V. With the stability of the threshold voltage, on-state characteristics, and blocking characteristics; this shows that this device would perform reliably within commercial applications that include stressful switching conditions.
+ Smart Watch Rssi Localization And Refinement For Behavioral Classification Using Laser-Slam For Mapping And Fingerprinting
  J. D. Carlson; M. Mittek; S. A. Parkison; P. Sathler; D. Bayne; E. T. Psota; L. C. Pérez; S. J. Bonasera
Abstract:  As a first step toward building a smart home behavioral monitoring system capable of classifying a wide variety of human behavior, a wireless sensor network (WSN) system is presented for RSSI localization. The low-cost, non-intrusive system uses a smart watch worn by the user to broadcast data to the WSN, where the strength of the radio signal is evaluated at each WSN node to localize the user. A method is presented that uses simultaneous localization and mapping (SLAM) for system calibration, providing automated fingerprinting associating the radio signal strength patterns to the user's location within the living space. To improve the accuracy of localization, a novel refinement technique is introduced that takes into account typical movement patterns of people within their homes. Experimental results demonstrate that the system is capable of providing accurate localization results in a typical living space.

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+ Thermal Analysis Of 4H-Sic Dmosfet Structure Under Resistive Switching
  B. N. Pushpakaran; S. B. Bayne; A. A. Ogunniyi
Abstract:  This research investigates the electro-thermal switching characteristics and lattice temperature profile of a two dimensional (2D) silicon carbide (4H-SiC polytype) Metal Oxide Semiconductor Field Effect Transistor (MOSFET) cell under resistive switching using Silvaco ATLAS Technology Computer Aided Design (TCAD) physics based simulation software. Physics based models were included to account for recombination effects, bandgap narrowing, low field and high field mobility and lattice heating. The electro-thermal simulation was performed at an ambient lattice temperature of 300K. The device was simulated for 100 A/cm2 and 1000 A/cm2 drain current densities using a 1 kHz 50% duty cycle gate signal consisting of two cycles and 1.6 kHz 80% duty cycle signal consisting of three cycles. The analysis of lattice temperature profile revealed the formation of thermal hot spots in the vicinity of the (Junction Field Effect Transistor) JFET region in the DMOSFET structure during the switching phase and at the edge of the channel during the conduction phase. The magnitude of temperature rise was dependent on the drain current density used during the simulation.

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+ University-Industry Partnership In Semiconductor Engineering
  Dallas, T; Karp, T; Nutter, BS; Lie, YCD; Gale, RO; Cox, R; Bayne, SB
Abstract:  We describe a long-standing and successful university-industry partnership in semiconductor device engineering with a primary focus on product and test engineering. The partnership, now (2013) in its 15(th) year, relies on a symbiotic relationship that has evolved over the years to reflect semiconductor industry trends and advancing university capabilities. The success of the partnership is due to a multifaceted approach with an emphasis on frequent interactions between company personnel and university faculty and students. These interactions feed the core component of the program, student internships. These internships, for which students can obtain course credit, are done at both the undergraduate and graduate level and provide a nearly seamless pathway from school to full-time employment.
Publication Year:  2013
+ Design Of An Advanced Modular Automated Evaluation System For Experimental High Power Sgtos
  S. Lacouture; K. Lawson; S. Bayne; M. Giesselmann; H. O'Brien; A. Ogunniyi; C. J. Scozzie
Abstract:  An advanced evaluation system for experimental high power Super Gate Turn Off Thyristors (SGTOs) with built - in custom data acquisition and characterization electronics was designed and built in a cooperative agreement between engineers at Texas Tech University's Center for Pulsed Power and Power electronics (P3 E) laboratory and research scientists at Army Research Lab (ARL). The system consist of a Pulse Forming Network (PFN) energized by a rapid capacitor charger, a data acquisition system which records chosen waveforms for each test cycle and a curve tracing module which the test devices are mechanically switched into to record current and voltage characteristics at arbitrary intervals between high power cycles. Testing is completely automated, with all test parameters including charge level, repetition rate, volume, etc. set within a windows based GUI. The evaluation system has successfully recorded changing I - V characteristics before actual physical failure in several devices. Extremely high volume testing has also been carried out with one device having been cycled over 42,000 times at moderate (2.5 kA) conduction levels.

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+ Design Of An Advanced Modular Automated Evaluation System For Experimental High Power Si And Sic Sgtos
  K. Lawson; S. Lacouture; S. Bayne; M. Giesselmann; H. O'Brien; A. Ogunniyi; C. J. Scozzie
Abstract:  An advanced evaluation system for experimental high power silicon (Si) and silicon carbide (SiC) Super Gate Turn Off Thyristors (SGTOs) with custom data acquisition and characterization electronics was designed and built in a cooperative agreement between engineers at Texas Tech University's (TTU) Center for Pulsed Power and Power Electronics (P3E) laboratory and research scientists at the U.S. Army Research Lab (ARL). The system consists of a 4.4 kJ Pulse Forming Network (PFN) energized by a 10 kW rapid capacitor charger developed at TTU, a data acquisition system which records chosen waveforms for each test cycle and a curve tracing module which the test devices are mechanically switched into to record current and voltage characteristics at arbitrary intervals between high power cycles. Testing is completely automated, with all test parameters including charge level, repetition rate, volume, etc. set within a custom windows based GUI. The evaluation system has successfully recorded changing I-V characteristics before actual physical failure in several devices. Extremely high volume testing has also been carried out with one device having been cycled over 30,000 times at moderate (2.5 kA) conduction levels. This paper expands on work presented at the 2012 Power Modulator Conference and presents newly acquired data and modifications.

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+ Electro-Thermal Transient Simulation Of Silicon Carbide Power Mosfet
  B. N. Pushpakaran; S. B. Bayne; A. A. Ogunniyi
Abstract:  This research illustrates the transient performance of N-channel silicon carbide (4H-SiC) power MOSFET rated for a blocking voltage of 1200V and drain current density of 100A/cm2. The simulation of vertical D-MOSFET half cell structure was performed at room temperature of 300K. The 2D device model was created and simulated using Silvaco© ATLAS Technology Computer-Aided Design (TCAD) physics based simulation software. Physics based models were used to accurately model electrical device parameters including carrier mobility, recombination effects, bandgap narrowing, impact ionization and lattice heating.

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+ High Performance, Large-Area, 1600 V / 150 A, 4H-Sic Dmosfet For Robust High-Power And High-Temperature Applications
  L. Cheng; A. K. Agarwal; M. Schupbach; D. A. Gajewski; D. J. Lichtenwalner; V. Pala; S. -H. Ryu; J. Richmond; J. W. Palmour; W. Ray; J. Schrock; A. Bilbao; S. Bayne; A. Lelis; C. Scozzie
Abstract:  In this paper, we report our recently developed 2nd Generation, large-area (56 mm2 with an active conducting area of 40 mm2) 4H-SiC DMOSFET, which can reliably block 1600 V with very low leakage current under a gate-bias (VG) of 0 V at temperatures up to 200°C. The device also exhibits a low on-resistance (RON) of 12.4 mΩ at 150 A and VG of 20 V. DC and dynamic switching characteristics of the SiC DMOSFET have also been compared with a commercially available 1200 V/ 200 A rated Si trench gate IGBT. The switching energy of the SiC DMOSFET at 600 V input voltage bus is > 4X lower than that of the Si IGBT at room-temperature and > 7X lower at 150°C. A comprehensive study on intrinsic reliability of this 2nd generation SiC MOSFET has been performed to build consumer confidence and to achieve broad market adoption of this disruptive power switch technology.

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+ Multiple Cell Ac/Dc Smart Battery Design
  T. J. Rosson; S. Bayne; R. Gale
Abstract:  Traditional multi-cell battery packs use a fixed configuration to connect multiple individual battery cells in fixed configurations to achieve pre-determined voltage and current. Even with modern advances in battery chemistry and greater power density, this fixed configuration results in low reliability, low fault tolerance, and non-optimal energy conversion efficiency. This system of manufacture is hindering advances in battery performance. This paper proposes a novel scheme to manufacture batteries by individualizing cells. By changing the packaging and adding low cost circuitry, a single cell in a battery pack will be able to control its orientation with other cells in a system. The idea has potential to revolutionize the way in which battery systems are developed and controlled. By using Texas Instruments value line MSP430 microcontrollers, the cost of the system can be minimized. The use of these low cost microcontrollers makes it possible to monitor voltage and temperature levels on individual cells. Also, by utilizing the same microcontroller, the individual cell is capable of shifting individual battery cells from off state, to a positive or negative polarity. The ability to switch single cells will make it possible to create a multi-level DC output. This independent switching scheme will also make it possible to create a modified sine wave AC output. The possibilities of switching to negative polarity will double the peak-to-peak voltage of the AC waveform. The battery will also be capable of identifying and implementing only the cells that are in optimal condition. Using cells at optimal temperature and state of charge will prolong the life of each cell. A battery system that individualizes each cell into a replaceable package makes replacement of "dead cells" possible. These are the cells that currently cause traditional battery packs to be replaced. With such systems available, not only will efficiency of large multi-cell battery systems increase, but with replaceable cells the cost of ownership of a complete battery pack will decrease over the lifetime of the system.

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+ Pulsed Power Switching Of 4H-Sic Vertical D-Mosfet And Device Characterization
  A. Bilbao; W. B. Ray; J. A. Schrock; K. Lawson; S. B. Bayne; L. Cheng; A. K. Agarwal; C. Scozzie
Abstract:  The purpose of this research is to characterize and compare CREE's new N-Channel Silicon Carbide (4H-SiC) vertical power D-MOSFET with CREE's previous generation of N-Channel Silicon Carbide (4H-SiC) vertical power D-MOSFET. Changes made to the newest MOSFET design lead to a 400% increase in pulsed current handling capability over the previous generation device with the same active area.

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+ Reliable Operation Of Sic Junction-Field-Effect-Transistor Subjected To Over 2 Million 600-V Hard Switch Stressing Events
  Steiner, B; Bayne, SB; Veliadis, V; Ha, HC; Urciuoli, D; El-Hinnawy, N; Borodulin, P; Scozzie, C
Abstract:  A necessity for the successful commercialization of SiC power devices is their long term reliability under the switching conditions encountered in the field. Normally-ON 1200 V SiC JFETs were stressed in repetitive hard-switching conditions to determine their fault handling capabilities. The switching pulses were generated from an RLC circuit, where energy initially stored in capacitors discharges through the JFET into a resistive load. The hard-switching included one million repetitive pulsed hard-switching events at 25 degrees C from a drain blocking-voltage of 600 V to an on-state current of 67 A, and an additional one million 600-V/63-A pulsed hard-switching events at 150 degrees C. The JFET conduction and blocking-voltage characteristics are virtually unchanged after over two million hard switching events proving the devices are reliable for handling high surge-current faults like those encountered in bidirectional circuit breaker applications.
Publication Year:  2012
+ Alpha Schottky Junction Energy Source
  Litz, MS; Fan, ZY; Carroll, JJ; Bayne, S
Abstract:  Isotope batteries offer solutions for long-lived low-power sensor requirements. Alpha emitting isotopes have energy per decay 103 times that of beta emitters. Alpha particles are absorbed within 20 mu m of most materials reducing shielding mitigation. However, damage to materials from the alphas limits their practical use. A Schottky Barrier Diode (SBD) geometry is considered with an alpha emitting contact-layer on a diamond-like crystal semiconductor region. The radiation tolerance of diamond, the safety of alpha particles, combined with the internal field of the SBD is expected to generate current useful for low-power electronic devices over decades. Device design parameters and calculations of the expected current are described.
+ Analysis And Comparison Between Two Wind Farms Consisting Of 500Kw Midsize Turbines And 1.5Mw Turbines
  S. R. Pappu; S. Nimmagadda; S. B. Bayne
Abstract:  This paper compares the characteristics of two wind farms of same power capacity having two different size generators. The research compares the performance of mid-size turbines to large turbines. The systems were modeled in MATLAB-Simulink. With rapid development in wind power generation it's necessary to study the different characteristics of wind farms having different generator configurations. A 9MW wind farm consisting of eighteen Fixed Speed Induction Generators (FSIG) with STATCOM at the terminals of the wind farm is compared to a 9MW wind farm consisting of six Doubly Fed Induction Generators (DFIG) interfaced with Power Electronics on the rotor. The models of FSIG wind power generation system and DFIG wind power generation system connected to the grid are built. An analysis on total power available for transmission, reactive power consumption at different wind speeds (cut in, rated, cut off), power loss due to loss of turbines.

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+ Avalanche Breakdown Energy In Silicon Carbide Junction Field Effect Transistors
  Hinojosa, M; Bayne, S; Veliadis, V; Urciuoli, D
Abstract:  The energy dissipation capabilities of a 4H-SiC, 1200 V, 0.1 cm(2) JFET operating in blocking mode were investigated. These devices, which are used in bidirectional solid-state circuit breaker applications, can conduct a current of 13 A in forward-conduction mode, and typically block a voltage up to 1200 V in reverse bias mode. In this document, the blocking limits of the device were pushed slightly to the point where avalanche breakdown occurs. A high voltage, short-pulse generator was designed and constructed to drive the JFET into this state and to monitor the dissipated energy. The devices were able to handle up to 18.14 mJ.
+ Design Of An Automated Test Bed For Experimental Si And Sic Sgto Devices
  K. Lawson; S. Lacouture; S. B. Bayne; M. Giesselmann; T. Vollmer; H. O'Brien; C. Scozzie; A. Ogunniyi
Abstract:  In a collaborative effort between Army Research Lab (ARL) and Texas Tech University's center for Pulsed Power and Power Electronics (P3E) lab, a high power, high energy test bed meant to characterize experimental Si and SiC Super Gate Turn Off (SGTO) devices was designed and built. The system was engineered to run the devices through an arbitrary number of test cycles while recording all pertinent data automatically. Test parameters are set through a windows GUI which communicates with a microprocessor - based control system that orchestrates timing and settings of each subsystem as well as acquiring voltage and current waveforms with high speed ADCs operating simultaneously in parallel. The test waveform itself is generated by a Pulse Forming Network (PFN) which accurately controls rise time, fall time and pulse width. The PFN is charged by a Rapid Capacitor Charger (RCC) system designed at the P3E lab that is capable of 10 kW and allows precise charge voltage levels to be set. Waveforms are acquired through isolated probes specifically designed to capture desired signals even in the presence of a large bias voltages.

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+ Evaluation Of High Power Experimental Sic Sgto Devices For Pulsed Power Applications
  Lacouture, S; Lawson, K; Bayne, S; Giesselmann, M; O'Brien, H; Scozzie, CJ
Abstract:  The development of new semiconductor designs requires that extensive testing be completed in order to fully understand the device's characteristics and performance capabilities. This paper describes the evaluation of experimental Silicon Carbide high power Super Gate Turn Off Thyristors (SiC SGTOs) in a unique test bed that is capable of stressing the devices with very high energy/power levels while at the same time mimicking a realistic, real world application for such devices.
+ Evaluation Of Hub Concept For Wind Turbines
  S. R. Pappu; S. B. Bayne
Abstract:  This paper simulates the transient response of three wind farms interconnected, rated 9MW each. Each wind farm consists of six Doubly Fed Induction Generator (DFIG) turbines rated at 1.5MW each, interfaced with power electronics on the rotor side. The three wind farms connected to the grid are built and modelled in MATLAB-Simulink. With the rapid development in Generation Interconnect Requests and development of the Hub concept, it is necessary to model the interconnection of wind farms to study the transient characteristics. The three wind farms are interconnected at a single point on the transmission line to increase efficiency and reliability. Analysis on voltage stability of wind farms due to faults on the neighbouring wind farm was done. A STATCOM was installed at the terminals of each wind farm to provide additional voltage stability and reactive power capabilities.

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+ Flywheel Energy Storage Systems For Wind Turbine Grid Frequency Stability - A Review
  Durukan, I; Ekwaro-Osire, S; Bayne, SB
Abstract:  Most recent grid codes require wind turbines to contribute to the recovery of frequency drops in the grid. More of the recently build wind turbines use variable speed generators. Unlike fixed speed generators, these generators do not naturally contribute to the recovery of the frequency drop since the rotor rpm is decoupled from the grid frequency. This decoupling is achieved by controller and power conditioning units. The studies reviewed in this paper focused on the design of such a controller so that the wind turbine could react to frequency drops. Another approach to responding to frequency drops is to connect an energy storage system to the DC bus of variable speed generator. Flywheels have been used as energy storage systems to fill energy gaps in several applications and can be used for frequency recovery application for wind turbines as well. The objective of this study was to demonstrate the improvement of frequency stability of wind turbines connected to electrical grids in the presence of flywheel energy storage systems (FESS). Studies reviewed show that FESS can enhance the power quality and frequency stability of wind turbines connected to an electrical grid.
+ Power Quality Analysis Of A Sensitive Load Using A Phasor Measurement Unit
  S. Pappu; A. Rahnama; M. Tovar; S. Bayne; B. Little; S. Friend; M. Borhani
Abstract:  This paper discusses the set up and analyses of Power Quality using a Phasor Measurement Unit (PMU) located at a Semiconductor Foundry Fabrication Facility (sensitive load). The paper demonstrates the setting up of an SEL 421 PMU at the Facility (software and hardware), data archiving and real time waveform capture of voltages, currents and frequency. A code was developed for filtering the data collected from the PMU in MATLAB. A GUI was developed in MATLAB. The GUI analyses the data from the PMU and highlights aberrations in the values of Voltages and Frequency from the Power Quality limits for sensitive loads. The paper evaluates a unique method for analysis of Power Quality before the installation of a wind turbine directly feeding the Facility so as to set a standard after the wind turbine is installed.

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+ Pspice Modeling Of Silicon Carbide Mosfets And Device Parameter Extraction
  A. Bilbao; S. Bayne
Abstract:  The goal of this research is to develop device models for Silicon Carbide (SiC) MOSFETs. Parameters are extracted and used to create PSPICE models that can be utilized for circuit simulation. Two silicon carbide power MOSFETs made available by CREE Semiconductor are considered. The first silicon carbide power MOSFET tested is the CMF20120A64410. This MOSFET features a 1200V drain-to-source breakdown voltage and 30A continuous current capacity. The second device tested is an experimental MOSFET that is still not available in the market as of the date of this paper. The experimental MOSFET features a 1200V drain-to-source breakdown voltage and 80A continuous current capability. Custom made circuits are developed for extracting some of the parameters. In some cases where the tests only require low drain current, a HP B1505A curve tracer is used to aid the development of the model. The effect of temperature over the gate threshold voltage is also investigated. By externally increasing and monitoring the die temperature of the SiC MOSFETs, new device parameters can be extracted and modeled. Once the parameters are extracted they are converted into a PSPICE model. The model is tested and compared to the real device to verify accuracy. This is achieved using custom switching circuits with both inductive and resistive loads and software suites like MATLAB.

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+ Reliable Operation Of 1200-V Sic Vertical Junction-Field-Effect-Transistor Subjected To 16,000-Pulse Hard Switching Stressing
  Lawson, K; Alvarez, G; Bayne, SB; Veliadis, V; Ha, HC; Urciuoli, D; Scozzie, C
Abstract:  A necessity for the successful commercialization of SiC power devices is their long term reliability under the switching conditions encountered in application. Normally-ON 1200 V SiC JFETs were stressed in hard-switching conditions to determine their fault handling capabilities. The hard-switching included single shot tests ranging from drain voltages of 100 V to 500 V and repetition rate tests at 1 Hz, 5 Hz, 10 Hz, and 100 Hz with peak currents exceeding 100 A (8 times the rated current at 250 W/cm(2)). The JFET conduction and blocking-voltage characteristics are unchanged after 16,000 pulsed and numerous single shot hard switching events proving the devices are reliable for handling high surge-current faults.
Publication Year:  2011
+ Evaluation Of Experimental Silicon Sgto Devices For Pulsed Power Applications
  S. Lacouture; S. B. Bayne; M. G. Giesselmann; K. Lawson; H. O'Brien; C. J. Scozzie
Abstract:  The development of new semiconductor devices requires that extensive testing be completed in order to fully understand the device characteristics and performance capabilities. This paper describes the evaluation of experimental Silicon high power Super Gate Turn Off Thyristors (Si SGTOs) in a unique testing environment. The SGTOs are capable of blocking in the forward direction up to 5kV and are also capable of handling several kA when pulsed. The device structure is asymmetric so the reverse blocking of these devices is only a couple hundred volts. Since these devices are SGTOs special consideration had to be given to the gate trigger circuit so that noise would be minimized on the gate therefore preventing false triggering of the devices.

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+ Modeling And Control Of Directly Connected And Inverter Interfaced Sources In A Microgrid
  M. Chamana; S. B. Bayne
Abstract:  There has been a keen interest on Distributed Generation (DG) due to their restricted goals of meeting local loads and improving reliability of the overall system. Microgrids (MGs) are connected to the main grid through a Point of Common Coupling which separates the former from the latter. At the time of an intentional islanding or fault at the grid level, a microgrid is able to disconnect itself from the rest of the grid and operate by itself. A microgrid may contain both directly connected and inverter interfaced sources with different control configurations. When disconnected or islanded from the main grid there are various approaches to share the load, one of them being master-slave control where a storage device may become the reference DG to set the nominal voltage and frequency. When the main grid is brought back to normal operation, the microgrid is able to resynchronize itself to the main grid only when it meets certain conditions so as to avoid transients. All the microsources, power electronics and their control with power management were developed in Matlab/Simulink.

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+ Modeling, Control And Power Management Of Inverter Interfaced Sources In A Microgrid
  M. Chamana; S. B. Bayne
Abstract:  Microgrid is a combination of Distributed Energy Resources (DERs) and loads that are connected within a locality. Microgrids are connected to the main grid through a Point of Common Coupling (PCC) which separates the former from the latter. In grid connected mode all the Distributed Generators (DGs) are PQ controlled with pre-defined set-points and the power imbalance is imported from or exported to the main grid. At the time of an intentional islanding or fault at the main grid level, a microgrid is able to disconnect itself from the rest of the grid and operate by itself. A microgrid may contain both directly connected and inverter interfaced sources with different control configurations. When disconnected or islanded from the main grid there are various approaches to share the load, one of them being the master-slave control where a storage device (battery) becomes the reference DG to set the nominal voltage and frequency for the entire microgrid. The State Of Charge of the battery is considered for the battery dynamics when in islanded mode for bi-directional flow. All the microsources, power electronics and their control with power management were developed in Matlab/Simulink.

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+ New Asic Architecture Development For Energy Harvesting
  D. Reddy; N. S. Beniwal; S. B. Bayne
Abstract:  This paper presents the design of an ultra-low power energy scavenging system capable of collecting and managing energy from ambient vibrations and RF electromagnetic waves. Firstly, low power and broadband equiangular spiral antenna which is able to receive and rectify ambient RF radiation is designed and simulated. The energy transducers, commercial piezoelectric generators with a wide frequency range of 26 "“ 205Hz and the designed spiral antenna are evaluated and characterized to maximize the efficiency. Secondly, the power electronic circuits involved in the energy harvesting are designed in 0.6um CMOS technology and the simulation results are presented. Charge pumps, rectifier and Low drop-out regulator (LDO) were optimized to operate with low voltage ranges since the energy produced by the piezoelectric generator and the equiangular spiral antenna is found to be in microwatts and less from the test results. The AC output from the piezoelectric generator is rectified and boosted to required output level using an AC-DC charge pump. Rectifier and DC-DC charge pump are adopted for the efficient conversion of voltage from the broadband antenna. A back-up battery is provided for the start-up of DC-DC charge pump at low input conditions. An LDO with a drop-out voltage of less than 400mV is designed to provide regulated output of 4.1V to the battery. Finally, the collected energy is stored in a 50uAh capacity thin film battery which is intended for low-voltage and low-power applications.

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+ Unique High Energy Test Bed For Experimental Thyristor Devices
  S. Lacouture; S. B. Bayne; M. G. Giesselmann; K. Lawson; H. O'Brien; C. J. Scozzie
Abstract:  This paper details the design of a test platform for experimental silicon and silicon carbide Super Gate Turn Off devices (SGTOs) capable of stressing the devices with very high energy/power levels while at the same time mimicking a realistic, real world application. To this end an aircraft ground power Motor - Generator set was acquired consisting of a high frequency synchronous generator, a D.C. powered brushless exciter machine, and a 100 HP induction motor. The Si SGTO devices were then placed in a three phase controlled rectifier circuit connected between the generator output and a low impedance high power purely resistive load.

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Publication Year:  2010
+ Hardware-In-The-Loop Testing Of Gm Two-Mode Hybrid Electric Vehicle
  T. Maxwell; K. Patil; S. Bayne; R. Gale
Abstract:  This paper presents Hardware-in loop (HIL) testing for GM two-mode hybrid. First Modeling and simulation of GM two-mode hybrid using model based design (MBD) process is performed. HIL testing is performed using dSpace MicroAutoBox (MABX) and National Instruments PXI. The control strategy compiled code is uploaded to MABX using ControlDesk software and the corresponding plant model is transferred to PXI using NI Veristand software. This work is part of EcoCAR competition by the Texas Tech University. EcoCAR: The Next Challenge is a vehicle engineering competition organized by the US Department of Energy (DOE) and General Motors (GM).

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+ Transient Analysis Of Silicon Carbide Mosfet Switches
  K. Lawson; S. B. Bayne
Abstract:  This research was conducted to determine the transient performance of Silicon Carbide MOSFET devices. The device under test for these results is a CREE CMF20120D D-MOSFET rated for a blocking voltage of 1200 V and a forward conduction current of 20 A. The first test involves testing the limit of voltage rise time, or the dV/dt of these devices to determine when the device turns itself on. The second test studies the effects of large current pulses, 10x the rated current, on these devices to determine how well these devices are able to handle over current situations. For both of these tests a test bed had to be designed and built.

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+ Vehicle Development Process For Ecocar: The Next Challenge Competition
  K. Patil; T. Maxwell; S. Bayne; R. Gale
Abstract:  Present work investigates development of the vehicle design in the Texas Tech University EcoCAR program with industry standard vehicle development process (VDP). The three different architectures considered are fuel cell, GM two-mode hybrid and belt alternator/starter system (BAS+). The design process started from the architecture selection with the use of PSAT software. Based on results, best choice of vehicle architecture among the three considered is two-mode hybrid. With Matlab/Simulink environment vehicle model is developed. The plant model and controller model is tested with software-in-loop (SIL) and hardware-in-loop (HIL) simulations. The testing of this stage is done with NI PXI and dSPACE MicroAutoBox.

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Publication Year:  2007
+ Electro-Thermal, Transient, Mixed-Mode 2D Simulation Study Of Sic Power Thyristors Operating Under Pulsedpower Conditions
  Hillkirk, LM; Hefner, AR; Dutton, RW; Bayne, SB; O'Brien, H
Abstract:  An electro-thermal, transient device simulation study of Silicon Carbide (SiC) power thyristors operating in a pulsed-power circuit at extremely high current density has been carried out within the drift-diffusion approximation and classical heat generation and transport theory using MEDICI* [1]. The convergence problems normally associated with Technology Computer-Aided Design (TCAD) simulations of SiC bipolar devices were overcome without artificially increasing the free carrier concentration by optical carrier generation. or by increasing the initial temperature (thermal carrier generation). The simulation results closely predict the actual operating conditions of the SiC thyristor in the pulsed-power circuit and are used to interpret the results of experimental failure limit studies [2]. It is shown that TCAD simulations can realistically predict the electrical and thermal properties of complex SiC bipolar semiconductor devices operating under fast transient, pulsed-power conditions.
+ Evaluation Of The Safe Operating Area Of A 2.0 Cm2, 4 Kv Si Sgto
  H. O'Brien; S. B. Bayne; W. Shaheen; T. Crowley
Abstract:  Summary form only given. The U. S. Army Research Laboratory (ARL) has been evaluating high voltage, high current modular silicon super-GTOs (SGTOs) developed by Silicon Power Corporation (SPCO) for ARL. The modular approach, combining SGTO die in parallel and in series, has been successful for devices implemented in both 10 kV, 80 kA and 10 kV, 400 kA configurations. It is desirable to fully characterize the SGTOs at the individual chip level, though, in order to fully understand the capabilities of any scaled up device packages. To supply this study, SPCO modules containing eight Si die were altered so that each device could be switched independently while the other seven remained unused. Each SGTO was switched up to the point of destruction, which was evident in damage to the device's gate or to its anode-to-cathode high voltage blocking. SGTOs were pulsed in two separate test beds: one designed to produce narrow current pulses, and another designed for wider pulses approaching 1 ms. Peak current, rise time and action (I2t) limitations were evaluated across this spectrum of pulse widths to document the safe operating area (SOA) of the Si SGTOs. The peak current attained at a 2mus FWHM pulse width was 20 kA with a 10-90% rate-of-current rise time of 26 kA/mus. In the wider pulse circuit, single die were switched as high as 6.2 kA with an action value of 18 times 103 A2s. Waveforms for various SGTOs were analyzed, and a set of SOA curves was created to represent characterization of the SGTO die.

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+ Pulse Evaluation Of High Voltage Sic Diodes
  H. O'Brien; S. B. Bayne; W. Shaheen; A. K. Agarwal
Abstract:  Summary form only given. The U.S. Army Research Laboratory is evaluating silicon carbide semiconductor components to determine the range of high power and pulsed power applications for which SiC is a sensible material to use. With SiC's tolerances for high temperatures and high current densities, compact modules of SiC diodes might be ideal for protecting other high power circuit components under pulse conditions. This study evaluated SiC diodes with a footprint of 0.73 cm2 which were designed bv Cree, Inc. and packaged and pulse tested at ARL. The diodes are rated for 6 kV blocking and 50 A of continuous forward current. They were arranged to clamp reverse currents at the switching end of a large capacitor bank and were pulsed at a single shot rate both individually and in parallel. Individual diodes were pulsed as high as 5.9 kA (corresponding to an action of 4.5 times 103 A2s) for 25 single shots before failing, and as high as 5.0 kA (with an action of 3.5 times 103 A2s) for over 100 shots without failure. Groups of diodes were characterized on a curve tracer and matched based on on-state dV/dl slope, which ranged from 3.7-4.0 mOmega. Five diodes paralleled in the pulse testbed carried a total current of 23 kA with each diode sharing 19-21% of the total peak current. Modules consisting of 8-10 diodes in parallel will be similarly pulsed to reach a peak total current of 40 kA and will ultimately be combined in a single, compact package for higher current applications.

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+ Testing Of High Energy Density Capacitors
  T. Crowley; W. Shaheen; S. Bayne; R. Jow
Abstract:  The U. S. Army Research Lab (ARL) is investigating the capabilities of high energy density capacitors at narrow pulse widths from two different manufacturers for high current pulsed power applications. Breakthroughs in this technology would allow smaller capacitor storage to be possible while retaining the same capabilities. The discharge pulse widths of the test shots were between thirteen and fourteen microseconds. These pulse widths were taken from the full wave half maximum pulse width (FWHM). Both capacitors are rated for 12.5 kJ of energy and are 250 μF but have different volumes. The General Atomics Capacitors (GA-ESI 38982, 38994) have a total energy density of 1.3 J/cc while the manufacturer B"™s capacitor has an energy density of 0.64 J/cc. Both General Atomics"™ and manufacturer B"™s capacitors are polypropylene metallized film capacitors. While energy density is a major concern for our tests; attributes such as peak current, rise time, and high voltage lifetime were other factors to be considered. ARL is collaborating directly with General Atomics to help provide input and data in order to improve all properties of their capacitors.

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Publication Year:  2006
+ Evaluation Of 10 Kv, 80 Ka Si Sgto Switching Components For Army Pulsed Power Applications
  T. Crowley; H. O'Brien; W. Shaheen; S. B. Bayne
Abstract:  The U.S. Army Research Lab (ARL) is investigating the switching capabilities of advanced silicon devices for high current pulsed power applications. These solid state switches are intended to replace more traditional vacuum switches. The benefits of these switches are higher dl/dt, peak power levels and current densities, increased reliability and lifetime, and smaller switch volume. The peak current achieved by the device was 83.3 kA, with a 10% to 90% rise time of 3.5 mus while a 0.263 MA2s without failure. The peak power of the device during this test shot was 78.7 MW. ARL is collaborating with Silicon Power Corp. (SPCO) to evaluate super-GTO performance and improve upon switch/buss bar packaging for pulsed power applications

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+ Evaluation Of A 10 Kv, 400 Ka Si Sgto At High Di/Dt
  H. O'Brien; W. Shaheen; T. Crowley; S. B. Bayne
Abstract:  The evaluation of each 10 kV, 400 kA Si SGTO included a visual inspection and high-potting of each component module prior to pulsing. The complete unit was then switched in a low inductance RLC circuit to test voltage and current capabilities and maximize dl/dt. Devices were switched as many as 70 times without failure. Voltage sharing between the layers was within plusmn2%, and current sharing between the modules was plusmn5% of ideal sharing. The peak rate of current rise attained was 40 kA/mus, and the 50% pulse width of the current was 26 mus. The peak power switched was 1.06 GW, and the action of the forward current pulse reached 6.4 MA2s. This report includes details on the methods for evaluating the 400 kA SGTO, challenges faced and peak performance of the devices under single shot pulsing conditions

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+ Evaluation Of A 4 Mm X 4 Mm Sic Gto At Temperatures Up To 150°C And Varying Pulse Width
  H. O'Brien; W. Shaheen; S. B. Bayne
Abstract:  The U. S. Army Research Laboratory (ARL) is evaluating silicon carbide Super GTOs (SGTOs) to determine the extent of silicon carbide's capabilities as a possible replacement for silicon in future pulsed switching applications. Individual SiC die measuring 4 mmtimes4 mm were pulsed at high temperatures and varying pulse widths. These SGTOs were switched in an RLC circuit at temperatures up to 150 degC. At this peak temperature, they were switched as high as 3.2 kA and repetitively pulsed at 2.6 kA and 5 Hz for greater than 14,000 pulses. A pulse forming network (PFN) was also designed to increase the pulse width and the action seen by the SiC devices. At ambient temperature and a peak current of 2 kA, SiC SGTOs were switched in the PFN at a 50% pulse width of 40 mus and an action of 150 A2s. This report includes further data on high temperature and wide pulse width testing, as well as analysis of the devices' failure points

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Publication Year:  2005
+ Evaluation Of A 7 Kv 80 Ka Sgto Module
  R. L. Thomas; H. O'Brien; W. Shaheen; S. B. Bayne
Abstract:  This work was undertaken to investigate the switching performance of Super GTO's (SGTO) under conditions of fast rise times up to 25 kA/us, high peak current up to 80 kA, blocking voltage of 7 kV and pulse width of 100 us. The device under test is a switch that is made of two 3.5 kV modules placed in series; each containing eight SGTO die in parallel. The SGTO die developed by Silicon Power Corporation (SPCO) have a very small gate structure of approximately 10 mum. The benefit of this small gate structure is that it allows the device to reach full conduction faster than a conventional thyristor and is therefore optimized for fast turn-on (high di/dt). The SGTO die is a very efficient device having a current density of 29.7 A/mm2 at 10 kA. Each SGTO die can hold of 3.5 kV and can conduct 10 kA. The efficiency of the SGTO die warrants evaluation of this dual module SGTO switch that is rated at 7 kV and 80 kA. The evaluation of the dual module will also determine its overall ability to be used in other voltage and current configurations for various applications by determining its safe operating area (SOA). We have evaluated the switch at 6 kV at a maximum current of 86 kA over a 120 mus pulse width and with a di/dt of 25 kA/mus.

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+ Pulsed Power Switching Of A 4 Mm × 4 Mm Sic Thyristor
  H. O'Brien; W. Shaheen; S. B. Bayne
Abstract:  While silicon carbide (SiC) is beginning to make its way into the low voltage (300-1200 V) commercial power diode market, its capabilities in pulse power applications have yet to be proven. A previous investigation by the U.S. Army Research Laboratory (ARL) of SiC GTOs suggested that this emerging technology could provide pulsed current densities 40 to 60 times greater than is obtainable in silicon-based switches [1]. This study continues that earlier work by examining 4 mm times 4 mm 4H-SiC thyristors designed by CREE Inc. to reach 1 kV and 4 kA. These devices were successfully switched up to 3.89 kA with a current density reaching 56.1 kA/cm2, a specific rate-of-current-rise of 49 kA/mus/cm2 (for peak rise-time 7.8 kA/mus) and a pulse-width ranging from 2.0 mus to 2.6 mus. The thyristors were tested at both single shot and repetitive switching rates up to 5 Hz. Device characteristics were mapped on a curve tracer at different stages of testing, and the failure of each thyristor was analyzed.

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+ Silicon Carbide Power Semiconductor Module Development For A High Temperature 10Kw Ac Drive
  Katsis, D; Geil, B; Griffin, T; Koebke, G; Kaplan, S; Ovrebo, G; Bayne, S
Abstract:  A silicon carbide power module has been developed to demonstrate a high-temperature, 10kW AC drive application. Several goals for this development include temperature dependent parameter evaluation of parallel-connected transistors and junction barrier Schottky diodes at 150 degrees C operating temperature. Next, design of a high-thermal conductivity substrate to cool the modules based on predicted losses. Finally the integration into a variable speed AC drive using a DSP-based V/F motor controller. Test results for the 10 kW AC drive are provided to demonstrate power module performance up to 180 degrees C.
+ Thermal Performance Of Water-Cooled Heat Sinks: A Comparison Of Two Different Designs
  Salem, TE; Porschet, D; Bayne, SB
Abstract:  As power electronic applications continue to switch higher levels of voltage and current in smaller-sized component packages, the resulting increase in power density requires efficient thermal management. This paper compares the thermal performance for operating a MOSFET on a water-cooled pole-arrayed heat sink versus a novel water-cooled microchannel heat sink. Details are presented on an innovative technique for determining the thermal capacitance modeling parameter for the heat sinks from experimental data.
Publication Year:  2004
+ Evaluation Of 4H Sic Bipolar Junction Transistors
  Thomas, J; Kaplan, S; Bayne, S
Abstract:  4H-SiC bipolar junction transistors (BJTs) demonstrate excellent current carrying and blocking capabilities, and offer good high-temperature performance. Moreover, these devices are easier to parallel than their Si analogues due to negative current gain temperature coefficient. In contrast to vertical MOSFETs and JFETs, these devices do not have junction discontinuities in the active region, which makes these devices easily scalable to high blocking voltage requirements. This experiment will help MM2, F determine the safe operating areas of 1mm(2), 4mm(2), 9mm(2), and Darlington structure SiC BJTs constructed by CREE. The eventual goal of this work is to produce devices capable of blocking 1200V and operating at a maximum collector current of 10A. Ideally gains of 8 or more are desired at temperatures of 150 degrees C. These devices will be characterized at temperatures up to 150 degrees C. Next they will be put into a system containing a push-pull circuit, which will be used in to control the on and off states of the BJT under test. This report will serve as to document the operational status of the present devices and as feedback to CREE in order to guide the production of future devices. These devices were tested using single-shot and repetitive pulsing. The devices were tested individually, as well as in parallel pair configurations. During each of these experiments the devices were tested from room temperature to 150 degrees C.
+ Forward And Reverse Recovery Spice Model Of A Jbs Silicon Carbide Diode
  Giesselmann, M; Edwards, R; Bayne, S; Kaplan, S; Shaffer, E
Abstract:  The charged controlled model is presented as an effective method to simulate junction barrier schottky (JBS) silicon carbide diodes. Proven as a valuable approach for silicon devices, this model can also account for wide bandgap energy semiconductors. The model was implemented in Orcad's SPICE software package using analog behavioral modelling. The simulation combines the efficiency of a traditional static model with an improved charge controlled model representing transient characteristics of the semiconductor due to stored charge in the depletion layer. The result is an enhanced model that simulates in short period of time. Parameter extraction methods are used to help identify saturation currents, capacitance, resistance, voltages, and modelling coefficients. The simulation results in a close fit to the data taken during reverse recovery of a JBS SiC diode.
+ Silvaco Modeling Of A 10Kv Sic P-I-N Diode
  Thomas, RL; Morgenstern, M; Bayne, SB
Abstract:  To maximize the benefit of semiconductor technology, the U.S. military is requiring that the operating temperature for power electronic devices must be able to handle temperatures of up to150 degrees C. Power devices that use the wide band gap material silicon carbide (SiC) are being developed to provide large breakdown voltages and fast recovery times. When circuits call for high blocking voltages and fast reverse recovery times under adverse temperature situations, the p-i-n diode is the device presently used. To simulate the SiC device behavior, a modeling program named Silvaco was used to characterize a 5.76mm(2) 10kV SiC p-i-n diode manufactured by Cree under forward bias, reverse blocking and reverse recovery conditions. These simulations are then compared with test results from the actual device. Forward bias testing of the diode was conducted on a high power curve tracer and two different test circuits were developed to test reverse blocking and reverse recovery conditions respectively on sample diodes from Cree to add credibility to the Silvaco simulations. The results from the simulation and the experimental test were compared to verify the accuracy of the simulation and improve the prediction of high temperature device behavior in power electronics.
+ Thermal Evaluation Of Sic Gtos For Pulsed Power Applications
  Geil, BR; Bayne, SB; Ibitayo, D; Koebke, MG
Abstract:  For applications which require high peak current and fast rise time, Silicon Carbide (SiC) material is ideal due to its ability to tolerate high localized temperatures generated during switching. This research was performed to investigate SiC devices for pulse power applications and to analyze the failure of the devices. Seven 2 min x 2 mm SiC Gate Turn-Off thyristors (GTOs) manufactured by Cree were evaluated. The devices were tested at single shot and under repetitive stress using a ring-down capacitor discharge circuit. The current pulse width was 2 mu s with a peak current of 1.4 kA (current density of 94.6 kA/cm(2)) and a maximum di/dt of 2.36 kA/mu s. The maximum power dissipated within the devices was 240 kW. Thermal modeling of these devices was done using ANSYS to analyze the heating and cooling. The model used was a 2-D model that included the device package, and bonding materials. The maximum amount of power dissipated was calculated from the 1000 A, 2 ps pulse. No further power input was added to the model and the heat transfer was plotted on an exponential scale. It was found that heat applied to a 2 pin thick region of the fingers yielded a maximum temperature of 2,500 degrees C in the device. It took 1.0E(-02) seconds for this heat to dissipate and for the device to return to 23C. The minimum and maximum stresses were found to be -2.83E(+09) Pa and 4.06E(+08) Pa, respectively. It was also found that the thickness of the heat generation region did not affect the final time to cool, but did affect the maximum temperature reached.
Publication Year:  2003
+ Evaluation Of Sic Gtos For Pulse Power Switching
  Bayne, SB; Ibitayo, D
Abstract:  Certain applications require devices that can switch high peak current with fast rise times and narrow pulse width. This work was done as an initial study to investigate the performance of Silicon Carbide (SiC Gate turn-off thyristor (GTO) in these applications. The SiC GTOs were designed for high turn-off gain and not optimized for pulse applications. The GTOs were tested as discharge switches in a low inductance circuit delivering 2mus pulses with a maximum switching current of 1.4 kA (94.6 kA/cm(2)) and a current rise time of 2.4 kA/mus. All the devices were switched until failure. The failure modes will be discussed.
+ Silicon Vs Silicon Carbide Device Characterization
  Kaplan, S; Griffin, T; Bayne, S
Abstract:  Significant development of silicon carbide (SiC) material for device applications now allows circuit designers to more fully exploit its unique properties. The 4H-SiC structure provides the most favorable characteristics to optimize device speed and power handling capabilities. These include wide bandgap (3.2 eV), high dielectric breakdown (3.5 MV/cm), and high thermal conductivity (4.9 W/cm-K) [1]. By combining these properties, SiC devices are able to achieve fast reverse recovery and high reverse blocking voltages, along with excellent high temperature characteristics (case temperatures above 150 C). This makes these devices ideally suited to power electronics applications, where high power levels as well as fast switching are required. Many areas dominated by ultrafast recovery silicon (Si) diodes, might therefore be better suited to the application of SiC. In order to verify the efficacy of SiC devices, temperature dependent measurements were made on a sample of fast recovery Si and SiC diodes. This paper presents the results of these measurements, comparing critical characteristics of Si and SiC devices over a range of junction temperatures up to 150 C.
Publication Year:  2002
+ High-Temperature Switching And Evaluation Of 4H-Sic Gate Turn-Off Thyristors And Diodes Under Inductive Loads
  Bayne, SB; Tipton, CW; Scozzie, CJ; Griffin, TE
Abstract:  Future U.S Army electric motor control applications will require power semiconductor devices that operate for thousands of hours at case temperatures of 150 degreesC and higher. For reliable operation of silicon (Si)-based power electronics, the case temperature must be below 120 degreesC. Because of this temperature limitation of Si, new wide bandgap materials, such as silicon carbide (SiC) are being investigated. We report on a SiC gate turn-off thyristor (GTO) and SiC p-i-n diode operating at case temperatures up to 150 degreesC. For high power and high voltage applications the GTO is the switch of choice. In this study, currents up to 2 A where switched by the GTO under pulsed and continuous switching into an inductive load. The turn-on and turn-off gains, the on-state voltage, and the turn-on and turn-off times, as a function of temperature will be discussed.
Publication Year:  2001
+ Advanced Operational Techniques And Pn-Pn-Pn Structures For High-Power Silicon Carbide Gate Turns-Off Thyristors
  Shah, PB; Geil, BR; Ervin, ME; Griffin, TE; Bayne, S; Jones, KA; Oldham, TR
Abstract:  SIC GTO thyristors may soon be the best available choice for very high-power switching. At this time, we have developed new operational techniques, growth requirements and pn-pn-pn type structures to address the issues of high on-state voltage, poor turn-off gain, and inability to reach predicted breakover voltages. We present these findings using experimental measurements and numerical simulations.
Publication Year:  2000
+ Effect Of Blade Passing On A Wind Turbine Output
  Bayne, SB; Giesselmann, MG
Abstract:  Renewable energy such as wind and solar is a clean source of energy that can be integrated with conventional ways of producing energy. Power utility companies are looking at ways to integrate renewable energy with conventional methods. The Central and South West (CSW) renewable project was designed to investigate the role of solar and wind energy in a utility system. When connecting a wind farm to a utility grid, several issues must be taken into consideration such as stability, load matching, cost, location and the wind profile in relation to the peak loads on the system. One other parameter that is seldom considered is the effect of power oscillations due to turbine blades passing through their full are of motion and periodically encountering different wind speeds at different vertical positions. In the following, this effect is called 'blade passing' for short. This paper evaluates the effect of blade passing on the output voltage and current for a grid connected wind farm. The effect of blade passing as a function of the number of wind turbines connected to the grid is also investigated. The exact causes of the blade passing effect are also discussed.
+ The Use Of Thyristors For Repetitive Narrow Pulse, High Power Switching
  Bayne, SB; Portnoy, WM; Rohwein, GJ
Abstract:  Although high peak currents and fast risetimes can be simultaneously obtained for relatively short pulses in semiconductor thyristors have been obtained, no extensive study of thyristor operation under pulse conditions has been reported. This work demonstrates that reliable repetitive operation over millions of pulses can be obtained for pulse widths of around 1 ms.

Book

Publication Year:  2018
+ Electro-Thermal Tcad Model For 22 Kv Silicon Carbide Igbts
  Hinojosa, M; Ogunniyi, A; Bayne, S; Van Brunt, E; Ryu, SH
Abstract:  This section presents the current progress in the development of an electro-thermal numerical model for 22 kV 4H-silicon carbide IGBTs. This effort involved the creation of a TCAD model based on doping profiles and structural layers to simulate the steady-state and switching characteristics of recently-fabricated experimental devices. The technical challenge of creating this high voltage SiC IGBT model was incorporating semiconductor equations with sub-models representing carrier mobility, generation, recombination, and lattice heat flow effects with parameters conditioned for 4H-silicon carbide material. Simulations of the steady-state and switching characteristics were performed and later verified with laboratory measurements for an N-type SiC IGBT rated for 22 kV with an active area of 0.37 cm(2) and a drift region of 180 mu m.
Publication Year:  2005
+ 1000 V, 30 A Sic Bipolar Junction Transistors And Integrated Darlington Pairs
  Krishnaswami, S; Agarwal, A; Capell, C; Richmond, J; Ryu, SH; Palmour, J; Balachandran, S; Chow, TP; Bayne, S; Geil, B; Jones, KA; Scozzie, C
Abstract:  1000 V Bipolar Junction Transistor and integrated Darlington pairs with high current gain have been developed in 4H-SiC. The 3.38 mm x 3.38 mm BJT devices with an active area of 3 mm x 2 mm showed a forward on-current of 30 A, which corresponds to a current density of 333 A/cm(2), at a forward voltage drop of 2 V. A common-emitter current gain of 40 was measured on these devices. A specific on-resistance of 6.0 m&OHM;-cm(2) was observed at room temperature. The on-resistance increases at higher temperatures, while the current gain decreases to 30 at 275&DEG; C. In addition, an integrated Darlington pair with an active area of 3 rum x 3 mm showed a collector current of 30 A at a forward drop of 4 V at room temperature. A current gain of 2400 was measured on these devices. A BVCEO of 1000 V was measured on both of these devices.