Fault Current Bypass-Based LVDC Solid-State Circuit Breakers

This letter presents a new low-voltage direct-current fault current bypass-based solid-state circuit breaker (SSCB) using silicon-carbide
mosfet
s. The proposed SSCB provides the possibility to select the clamping voltage of metal–oxide varistors (MOVs) close to the nominal voltage of the dc system. This reduces voltage overshoots across the main switch and snubber components and extends the maximum allowable dc bus voltage on the SSCB. The MOVs are removed from the power line, and their leakage currents are completely eliminated. The clamping voltage of the MOV and its surge energy rating is considered to optimize the MOV. The
dv/dt
across the main switchis controlled by an auxiliary capacitor, where a design procedure is presented to optimize its value. Also, the stored inductive energy of the line inductor in dc systems is bypassed using an auxiliary branch and prevented from flowing through the faulty section to enhance the safety. LTspice simulations are presented to show the significance of the proposed SSCB. The experiments of 375 V/170 A/2.4 μs and 600 V/163 A/2.4 μs verify the effectiveness of the proposed design in practice.