Investigation of low-voltage solid-state DC breaker configurations for DC microgrid applications

Among current research issues of dc microgrids, short-circuit protection is very challenging because of the high rate of rise for the fault currents. Slow-acting electromechanical circuit breakers lead to system overdimensioning resulting in additional costs. Circuit breakers based on power semiconductor devices have the potential of fast interruption of fault currents. Unfortunately, the energy stored in parasitic inductors or system inductive components have the potential of resulting in overvoltage across the solid-state circuit breaker (SSCB). Metal oxide varistor (MOV), snubber circuits and freewheeling diodes are used to protect the semiconductor devices against overvoltage. Six configurations for a voltage clamp for a SSCB are analyzed in this paper when inductive components are present on the load sides. Finally, the experimental results verified that series connected diode and MOV clamping provides better overvoltage protection for the SSCB.