SiC Trench MOSFETs in Avalanche Mode with RC Snubber Circuit

Abstract:
Existing stray inductances in circuits may force power switches to enter the avalanche condition. Under avalanche condition, a power switch like SiC trench MOSFET can handle certain amount of current and energy before it gets destroyed. Ideas to utilize RC snubber circuits in parallel to the SiC switch or a half bridge are more and more discussed and helpful to reduce the effective stray inductance for switching and support a switching with less ringing. Such a circuit in parallel to SiC trench MOSFET provides current sharing and thereby, the SiC trench MOSFET is not fully stressed in given avalanche condition. This enables higher load currents that the SiC trench MOSFET can survive during turn-off. The use of an RC snubber circuit together with a SiC trench MOSFET may reduce the system total cost and increase the reliability of systems. This paper shows experimental and simulation results of SiC trench MOSFETs in avalanche mode with and without the use of RC snubber circuit.