April/May 2021

16 PCIM 2021 Issue 2 2021 Power Electronics Europe www.power-mag.com with a gate drive circuit employing a gate boosting technology based on a series capacitance and increased driver voltage. The MOSFET switch has been tested in pulsed operation with a resistive load up to 1 kV and 90 A at the load. A rise time of 3.5 ns at the load has been achieved. “A Unified View of GaN, SiC, Silicon FETs & IGBTs and their Price- Performance Analysis” will be presented by Shishir Rai, Founder & CEO, DiscoverEE, USA. In this view, different power devices in a V CE(ON) / V DS(ON) vs. V CE / V DS are shown. The power loss of each of these devices when used in a 3 KW DC/DC power converter application operating at 400 V and 800 V from low to high switching frequencies are modeled. The behaviour of power devices under each operating condition and their power loss performance with respect to their price ae compared. In the afternoon (2:30 pm) session SiC Devices II continues with “Investigation of Performance of Double-Trench SiC Power MOSFETs in Forward” by Juefei Yang, University of Bristol/UK. The dynamic switching performance of Silicon and SiC trench, double-trench, superjuction and planar power MOSFETs will be analyzed through a wide range of experimental measurements and modelings. The devices are evaluated on a high voltage clamped inductive switching test rig and switched with a range of switching rates and elevated junction temperatures. It is shown experimentally that CoolSiC MOSFET and SiC Double trench MOSFET show smaller switching losses with good stability in regard to temperature variations. “Analysis of Dynamic Transients of High Voltage Silicon and 4H-SiC NPN BJTs” will be performed by Chengjun Shen, University of Bristol/UK. High level injection, as a common phenomenon among bipolar devices, determines the switching speed between on-state and off-state. The advantages of the SiC BJTs in terms of switching transients over their Silicon counter-parts are illustrated by experimental measurements, modeling and simulation. It is shown that the delays increase with temperature and decrease in high collector currents. “Analysis of a 3.3kV-Si-SiC-Topology-Hybrid-Switch for Resonant ZVS Inverter Applications” is introduced by Michael Meissner, Research Associate, Helmut Schmidt University, Hamberg/Germany. Hybrid switches consisting of two different semiconductor materials (Si and SiC), two different technologies (MOSFET and IGBT) as well as two different topologies (NPC and inverter half bridge) are investigated within a resonant converter setup. The effects of different switching timings are analyzed in terms of losses. Additionally, the overall behavior of these three combinations are investigated within a special power recirculation test bench. “Analyzing Spectral Electroluminescence Sensitivities of SiC MOSFETs and their Impact on Power Device Monitoring” will be discussed by Lukas A. Ruppert, Research Associate, RWTH Aachen/Germany. This work analyzes the spectral sensitivities of SiC MOSFET’s electroluminescence (EL) and evaluates their impact on device monitoring approaches. Previous research demonstrated how the EL can be used for galvanically-isolated and high- bandwidth temperature and current sensing. However, the sensitivities of the spectrum to influences, such as gate biasing and degradation, have not been investigated. Thus, this work identifies these influences, examines their sensitivities and presents techniques that compensate them. The session SiC Devices III on the Tuesday (May 4, 1:00 – 2:00 pm) extends the subject with four streams. “A Flexible Test Setup for Long-Term Dynamic Characterization of SiC MOSFETs under Soft- and Hard-Switching Conditions” by Daniel Philipps, Norwegian University of Science and Technology, Norway, describes the concept and implementation of a test circuit for the dynamic characterization of SiC MOSFETs. The test setup enables both short and long term tests of SiC devices at blocking voltages of up to 900 V and currents of up to 100 A (and will be extended to higher blocking voltages of up to 1.8 kV). The stream “Parallel Operation of SiC MOSFETs” by Yuequan Hu, Manager Industrial Power Applications, Wolfspeed/USA, presents the issues and best design practices for paralleled MOSFETs, such as SiC MOSFETs. Because of fast switching and low switching power losses, SiC power switches have gained wide applications like drivetrain, EV chargers, server powers, and energy storage system. As load current and power increases, two or more SiC MOSFTs are often paralleled. There are some pitfalls that are best avoided. This paper will study the factors which affect the transient current and static thermal extensions to increase lifetime on component and system level, application analysis of Wide Band Gap Devices contra Silicon Devices in traction applications considering one level versus multilevel topologies, and smart digital control concepts for ultrafast switching devices considering high dv/dt values and di/dt values for the overall system design. The conference program will be complemented by user-oriented seminars on topics such as “Reliability Engineering in Power Electronics Systems”, a three-hour seminar held by Frede Blaabjerg, Francesco Iannuzzo and Huai Wang, Aalborg University, Denmark. The digital seminars will take place from May 10 – 12. SiC Devices On the Monday (May 3, 1:20 pm) the conference starts with the session SiC Devices I. The first stream is entitled “Parallel SiC Power Modules for the Use in High Current 3 Level ANPC Inverters with High Requirements on Output Frequency and THDi” and will be presented by J Kroschk, Development Manager at EAAT inb Germany. The rising complexity of frequency inverters results also in even higher requirements on power modules. E.g. high current inverters with high requirements on the output frequency and the total harmonic distortion require power modules with high current handling capacity at high switching frequencies. Both requirements can be fulfilled just by operating high current SiC power modules in parallel. The article describes a driver for two high current SiC MOSFET modules in parallel connection. The second stream “Challenges in Scaled High-Current SiC Measurements” comes from Jan Fuhrmann, Senior Engineer, University of Rostock in Germany. Scaled high-power measurements are the easiest way to evaluate the switching behavior of new semiconductors. Only one chip instead of a full module is needed, if the parasitic inductance is scaled. This scaled parasitic inductance can be placed everywhere in the commutation loop, but it also effects the switching behavior depending on the position, which is not expected. Several mistakes in the setup are shown and counter measures are described. With an optimized test setup, a good match between high- and low-side measurement can be achieved. “Fast SiC-MOSFET Switch with Gate Boosting Technology” is the subject of the third stream by Martin Sack, Scientific employee, Karlsruhe Institute of Technology, Germany. Gate boosting enables a considerable increase in switching speed for commercially available MOSFETs. In this work, a switch comprising three SiC-MOSFETs in parallel configuration has been combined “PCIM Europe 2021 covers achievements in power semiconductor devices based on WBG and Silicon materials, pioneering research on passive components and key technologies for elevated operating temperature future device packages as well as new converter designs with minimized parasitic components and smart digital control concepts”, underlines Professor Leo Lorenz, General Conference Director Photo: Mesago