Overvoltage Suppressing Snubber Circuit for Solid State Circuit Breaker considering System Inductances

Because of nature of the DC power distribution system, such as existence of power electronic converters with DC link capacitors and low system inductance, it has been known that the protection of DC system against short circuit fault would be difficult compared to AC system. The solid state circuit breaker (SSCB) is one of candidates for solution of DC protection thanks to its faster response and higher controllability and reusability compared to mechanical breaker or fuse. However, without proper overvoltage suppressing circuit, the overvoltage due to system inductance would collapse semiconductor switches in SSCB. In this paper, by the position of the inductance in the DC power distribution system, the effect of the inductance related to the SSCB overvoltage is analyzed. Also, the design of an overvoltage suppressing circuit absorbing the energy stored in the system inductance is addressed. And, a maximum operating range of the designed overvoltage suppressing circuit regrading system inductances is investigated. The effectiveness and performance of the overvoltage suppressing circuit is verified by the simulation and experimental results.