From Instability to Design Rules: Lessons Learned from Parallel 10 kV SiC Power Dies and Series-connecting High-Frequency GaN Converters

Abstract: (This webinar is sponsored by PELS TC 2) This webinar presents a historical and technical journey spanning more than a decade of research and development in magnetics, wide-bandgap power electronics. Beginning around 2013, it traces the evolution of work that ultimately led to a deeper understanding of two seemingly unrelated challenges: instability in series-connected GaN resonant converters and catastrophic failures when paralleling 10 kV SiC dies in multi-chip power modules. For several years, both problems limited semiconductor utilization and prevented the realization of expected system performance. The breakthrough emerged when observations from these two application domains were connected and combined with insights from a Japanese research publication. This led to a hypothesis regarding the fundamental mechanisms governing stability in high-voltage, high-speed switching systems. Extensive experimental validation confirmed the hypothesis and enabled the development of robust design methodologies. Today, these methods allow reliable paralleling of 10 kV SiC dies within power modules, as well as parallel operation of multiple 10 kV power modules, with performance matching design expectations. The webinar will discuss how oscillations previously overlooked by us was the factor in some cases causing instability and explosions. Understanding and managing the oscillations was essential for achieving stable operation, maximizing semiconductor utilization, and avoiding destructive failure mechanisms in next-generation high-voltage power converters.