Modeling of SiC MOSFETs Switching Oscillation for Dynamic Optimization with RC Snubber in the Half-bridge Circuit

With lower on-resistance and higher switching speed, SiC (silicon carbide) MOSFETs are widely used in high frequency power conversion circuits. The oscillation and voltage overshoot due to larger di/dt and dv/dt are the key challenges for realizing the full potential of SiC MOSFETs. RC snubber is found to improve the dynamic characteristics and mitigate the unbalanced paralleled current. The time-domain oscillation model of SiC MOSFETs with RC snubber is built in the turn-on and turn-off stage. From the perspective of reducing port impedance, the mechanism of RC snubber on the oscillation suppression is analyzed. Experimental results are given to validate the integrated effect for overshoot absorption, oscillation suppression and current sharing. Finally, the parameters optimization and design methods of RC snubber for better suppression effect are proposed.