Reliability investigation of repeated unclamped inductive switching in a diode-clamped SiC circuit breaker

This paper investigates the reliability of a solid-state circuit breaker with a clamped SiC diode as avalanche voltage after repeated cutoff operations. In solid-state circuit breakers, a clamping element is connected in parallel with a power semiconductor switch to divert the cutoff current. The SiC merged PiN Schottky (MPS) diode is one of the candidates for clamping elements in solid-state circuit breakers because of its high avalanche tolerance and good robustness after the shocks. Reliability tests indicate that no significant electrical characteristics are found for both the SiC MOSFET and the SiC MPS diode in the proposed circuit breaker, even after more than 10,000 unclamped inductive switching (UIS) cycles. These results are based on a 400 V, 50 A DC distribution system with the UIS condition. The results show that the SiC MPS diode works well as a clamped element for the long-term reliability of the solid-state circuit breaker.