Analysis of Miller Region Sustained Oscillations during Turn-on of High-Side 10kV SiC MOSFET

Abstract

Sustained Miller region oscillations are observed during turn-on of the high-side SiC MOSFET in a half-bridge 10kV power module during high-side double pulse testing at 6kV, 70A. The oscillations are analyzed and the cause is identified as a positive feedback loop forming between the common source inductance and the equivalent high-side Miller capacitance, with a current path through the parasitic power module capacitive couplings of the grounded baseplate. Using custom manufactured and prototype medium voltage power modules the cause is experimentally validated and a mitigation strategy is proposed, demonstrating complete elimination of the sustained oscillations.