Investigation of Switching Oscillations for Silicon Carbide MOSFETs in Three-Level Active Neutral-Point-Clamped Inverters

This article investigates the multifrequency switching oscillations of silicon carbide (SiC) MOSFETs in three-level active neutral-point-clamped (3L-ANPC) inverters under three typical commutation modes (i.e., full mode, outer and inner mode). Multiple switching-oscillation components with various frequencies are identified theoretically for both full- outer-mode commutations, due to their switching-loop diversities. Oppositely, mode exhibits a single oscillation component as only one loop is involved. Three types double-pulse tests (DPTs) conducted on 3L-ANPC inverter demonstrator SiC MOSFETs, extracted accordingly, which match well theoretical derivations. Moreover, other characteristics closely related, i.e., peaks, current overshoots, capacitive charges, energies, studied benchmarked according DPT results. It concluded that commutations share similarities terms oscillations, turn-on energies. The findings from this work provide comprehensive knowledge mechanisms associated fast-switched inverters. Accordingly, critical parasitic identified, specific design considerations proposed achieve switching-performance improvements.