Low Voltage DC Solid-State Circuit Breaker With Soft Turn-Off and Self-Charging Operation

Solid-state circuit breakers (SSCBs) present a promising solution for fault protection in direct current (dc) grids, offering ultra-fast response times and exceptional electrical lifespans. This article introduces a novel dc SSCB based on a silicon carbide metal-oxide-semiconductor field-effect transistor (SiC
mosfet
) and an active current injection circuit. It offers two main contributions. First, the main switch with reverse current injection enables the soft turn-
off
. This approach eliminates transient power shock in power electronics during turn-
off
, enhancing the circuit breaker's reliability. Second, the SSCB integrates a current-limiting inductor in series with the main switch. This inductor has two benefits: 1) it limits the rising rate of short-circuit fault current, thus reducing the circuit breaker's breaking capacity requirement; 2) the inductor charges the capacitor during the fault current rising, eliminating the need for auxiliary power supply circuits and complex switching operations. Optimized parameters are obtained by evaluating the effect of circuit breaker element parameters on the charging time and current commutation process. Then, the breaking performance of the proposed SSCB is evaluated by simulation and experiment. Finally, successful 910 A current breaker tests of the 375 V SSCB prototype demonstrate the feasibility and validity of the proposed solution.