MOV-RCD Snubber Design for Medium-Voltage SiC-Module Based Solid-State DC Circuit Breaker

Because of the lack of natural zero-crossing point and the existence of line inductance in a DC power system, the huge inductive energy can result in serious dv/dt issue across a DCCB during turning off, which could destroy power devices. RCD snubbers have been proposed to solve the dv/dt problem. However, investigations are still required to compare performance of RCD snubbers at different current magnitudes and different snubber capacitances. This paper proposes the design methodology of the MOV-RCD snubber for a medium voltage solid-state DCCB. Two prototypes are implemented to interrupt currents with different magnitudes. Experiments have validated that MOV-RCD snubbers can achieve smooth dv/dt with a fast response speed; besides, the response time depends on the current magnitude, implying that an MOV-RCD snubber can achieve the best performance only when the current is in a proper range.