Multi-Commutation Loop Induced Over-voltage Issue on Non-active Switches in Fast Switching Speed Three-Level Active Neutral Point Clamped Phase Leg

One of the popular converter topologies applied in high power dc-ac applications is the three-level active neutral point clamped (ANPC). Owing to relatively low switching frequency and slow switching speed of these topologies in high power applications, the commutation loop analysis in these topologies has not been fully conducted, and the over-voltage issue of non-active switches has not been thoroughly analyzed. This paper reveals an over-voltage issue on non-active switches in three level inverters due to multi-commutation loop. The detailed mode analysis during the commutation and related over-voltage issue are given. Finally, Si-based ANPC with 140 kHz switching frequency and SiC-based ANPC converters with 280 kHz switching frequency and high switching speed are tested respectively to compare and verify the over-voltage issue for non-active switches.