Research on Solid State Circuit Breaker Based on SiC MOSFET with Soft Switch off Method

Abstract:
Compared to silicon devices, Silicon carbide devices have lower on-state resistance, which can reduce on-state loss of DC solid state circuit breaker and reduce the pressure of cooling. However, silicon carbide MOSFET has smaller die area, higher current density than silicon MOSFET, which leads to weaker short-circuit ability, shorter short-circuit withstand time and higher protection requirement. In order to ensure the safe and reliable operation of silicon carbide power devices and improve the reliability of silicon carbide based DC solid state circuit breakers, the short circuit capability of silicon and silicon carbide MOSFET is analyzed and compared. And the short-circuit fault mechanism is revealed. In addition, gate-source voltage clamp methods are elaborated and compared. Combined with desaturation detection, a "soft turn-off" short-circuit protection method based on source parasitic inductance is proposed. Finally, a DC solid state circuit breaker prototype is built for experimental verification. Experimental results show that the proposed method can not only reduce the voltage stress of the power device, but also suppress the short circuit current.