Voltage Overshoot Suppression for SiC MOSFET-Based DC Solid-State Circuit Breaker

The transient overvoltage and oscillation phenomena, which are caused by its high switching speed in a solid-state dc circuit breaker based on the silicon carbide (SiC) metal-oxide- semiconductor field-effect transistor (MOSFET), are a crucial problem. This paper presents a simple and reliable method to manage such a problem. An equivalent circuit model for SiC MOSFET is primarily established. The influence of stray inductance in energy absorption loop on the turn-off characteristics of the dc circuit breaker is then analyzed. Subsequently, possible typical overvoltage suppression methods, such as using a resistor- capacitor snubber circuit and increasing gate resistance and parallel capacitance between the gate and source, are simulated and analyzed. Thereafter, a peak voltage suppression method that does not sacrifice the fast switching capability of SiC MOSFET is proposed based on different amounts of energy absorbed by metal oxide varistors (MOVs) with varying voltage levels. A basic principle for selecting a snubber MOV is proposed based on the voltage ratio of a snubber and an energy-absorbing MOV. Finally, the feasibility of the proposed method is verified via a small-scale principle prototype.