April/May 2021

20 PCIM 2021 Issue 2 2021 Power Electronics Europe www.power-mag.com application. Further, a non-compact ACF converter platform is used to evaluate performance results such as efficiency, EMI spectrum and device temperatures among other. “High-Power Density DC-DC Converters Using Highly-Integrated Half-Bridge GaN ICs” by Michael Basler, Research associate, Fraunhofer Institute IAF/Germany presents the development of high power density DC-DC converters by using monolithic integrated low-voltage half-bridge GaN ICs. The design is starting from the device to the packaging and the demonstrator level. An in-house fabricated monolithic integrated half-bridge is investigated with application-specific gate width ratio. On packaging level, the PCB embedding is compared with flip-chip. Finally, DC-DC converters with a power density of >1000 W/in? are realized by combining GaN Power ICs and advanced packaging technologies. SiC / GaN Devices II session on May 5 from 3:10 – 4:10 pm cover also four streams. “Temperature-Dependent Electrical Characteristics of a ß-Ga2O3 Schottky Barrier Diode” will be discussed by Florian Wilhelmi, PhD student, ZF Friedrichshafen/Germany. Gallium oxide has recently stirred interest as a possible material for power electronics. One of the first packaged ß-Ga2O3 Schottky barrier diodes is electrically characterized with static measurements at different junction temperatures and modeled in Spice. Ideality factors close to one and a smaller increase in differential on-resistance than Si and SiC reference devices when temperature rises show the potential of this devices for power and potentially high-temperature applications. “A Comparison of Ultra-fast Switching Power Devices” is given by Edward Shelton, Researcher, University of Oxford/UK. This stream makes a comparative study between the latest generation of SiC, GaN, Si CoolMOS and Si IGBT power devices, all switched as fast as possible using low inductance circuit design and no external gate resistors. A theoretical analysis of switch edge-rate and corresponding switching losses will be presented in the full paper, along with the circuit design and experimental test results. In “Identifying Unequal Temperature Distributions in SiC MOSFET Power Modules” by Christoph Lüdecke, Research associate, RWTH Aachen University/Germany a test setup is presented which allows to measure the temperatures of the individual dies of a power module in PWM operation. As DUT, a SiC MOSFET power module with a nominal voltage of 1200 V and a nominal current of 300 A is used. During operation, different parameters are varied and the effect on the temperature distribution is examined. The results of this work facilitate the design of future power modules with best utilization and no de-rating requirements. “Directly Cooled Silicon Carbide Power Modules: Thermal Model and Experimental Characterization” by Giuseppe Mauromicale, STMicroelectronics/Italy presents a 3D Finite Element Model (FEM) simulation to investigate the fluid dynamics behavior of a directly cooled SiC module structure. Furthermore, a two-step experimental procedure to thermally characterize the module is also reported. It comprises a calibration and, subsequently, the thermal impedance computation. The proposed FEM model is compared with experimental test results in order to demonstrate its effectiveness. Keynotes highlighting innovative application areas The first keynote stream on the Tuesday (May 4, 11:20 am) is entitled “Next- Generation SiC/GaN Three-Phase Variable-Speed Drive Inverter Concepts“ and will be presented by Johann Walter Kolar, Full Professor and Director of the Power Electronic Systems Laboratory, ETH Zürich, Switzerland. Next-generation variable speed drive (VSD) systems should feature high power density, not require shielded motor cables, offer high input and/or output voltage/motor speed range, ensure low motor power losses and/or applicability of conventional low-cost motor technology, and prevent dv/dt- related motor insulation stresses and bearing currents, as well as reflections on long motor cables, and finally should feature cognitive functionality for a seamless integration in Industry 4.0 environments. The talk will first discuss state-of-the-art VSD systems, define future requirements and highlight challenges originating from employing latest ultra-fast switching wide-bandgap (WBG) power semiconductors (GaN and SiC), which are a main enabling technology for further improving VSD performance. Next, different inverter output filter structures providing a continuous motor voltage waveform and/or preventing PWM-related effects as well as the filter design procedure and control are presented. Furthermore, examples of recently introduced commercial WBG VSD systems with output filter are described. Next, Advanced PWM inverter bridge-leg topologies, e.g. a quasi-two-level operated five-level flying capacitor approach will be discussed and new voltage DC-link and current DC-link inverter topologies featuring buck-boost functionality and a continuous sinusoidal output voltage are described, including experimental results of ultra-compact hardware demonstrators built at the Power Electronic Systems Laboratory of ETH Zurich. Furthermore, the advantages and challenges of a physical integration of motor and inverter are presented and the limitations originating from small chip sizes / low thermal capacitances concerning transient overload capability are highlighted. The second keynote stream (May 5, 11:20 am) will be given byHannes Stahr, Group Manager Technology - R&D, AT&S, Austria entitled “Next Generation of Power Electronics Module Packaging“. Fact figures of PCIM 2020 digital days