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ESE Seminar: “High-Frequency Power Conversion with Wide-Bandgap Semiconductors”
October 27, 2020 at 1:00 PM - 2:00 PM
With the commercialization of wide-bandgap power semiconductors, multi-MHz switching frequencies are more compelling and critical to meet new applications demanding leaps in power density and efficiency. In the past, studies of these converters reported significant gaps between measured and modeled performance, often attributed to dynamic RDS,ON in GaN HEMTs. In particular, the power semiconductors – which often drive thermal constraints – dissipated much more power than expected, rendering designs based on simulated values unusable. In soft-switched converters, which dominate at MHz frequencies, the semiconductor’s output capacitor is resonantly charged and discharged once per switching cycle. Recently, multiple papers have found significant losses from this process in silicon and wide-bandgap devices, explaining the unexpected power dissipation. With these losses known, the MHz-frequency design space can be reopened – if designers are careful about semiconductor selection. In this talk, I will discuss how to select the right device across material (GaN, SiC, or Si), device technology (superjunction or trench), size (lower RDS,ON is not always better), and, in some cases, manufacturer. Further, I will show how this selection drives thermal design, input voltage selection, and novel circuit topologies in a variety of high-performance demonstrations from 6.78 MHz all the way to 40.68 MHz.
Associate Professor of Electrical Engineering, Stanford University
Juan Rivas is an Associate Professor at Stanford’s Electrical Engineering department. Before, he served as an Assistant Professor at the University of Michigan and worked for GE Global Research in the high-frequency power electronics group. He has extensive experience in the design of dc-dc power converters working at MHz frequencies. He has published peer-reviewed work on power converters reaching up to 100 MHz using Si and WBG devices. He obtained his doctoral degree from MIT in 2006. His research interests include power electronics, resonant converters, resonant gate drive techniques, high-frequency magnetics, and finding new applications for power converters.