Investigation of DM and CM Reflected Wave Overvoltages and Their Mutual Suppression Using an Optimized Dwell-Time Approach in SiC-Based Two-Level Interleaved Motor Drives

This paper investigates differential-mode (DM) and common-mode (CM) reflected wave phenomena (RWP) in SiC-based interleaved three-phase motor drives and proposes a phasor-based dwell time optimization method for their concurrent mitigation. The study examines RWP at both the motor terminals (DM) and the neutral point (CM), identifying their influence on conducted EMI in both AC and DC sides of the drive. Experimental measurements reveal that terminal DM RWP exhibits high-frequency oscillations reaching up to 2 p.u., while neutral-point CM RWP reaches approximately 1.4 p.u. and manifests predominantly in the low-frequency range of the EMI spectrum, making it more challenging to suppress. The mitigation method is based on inserting a mid voltage step during the switching transition of the interleaved legs, where the dwell time is determined through phasor cancellation to suppress multiple resonances simultaneously. A 5 kW SiC interleaved inverter prototype with DM coupled inductors and a 4 m cable was tested using an RL motor emulator. The results demonstrate suppression for both DM and CM RWP, with corresponding EMI suppression, achieving up to 20 dB reduction at peak frequencies on both the AC and DC sides of the drive.