A Fully Zero-Current Turn-Off Topology for SiC Solid-State Circuit Breaker in Photovoltaic Storage and Charging DC Microgrids

Solid-state circuit breakers (SSCBs) enable rapid and reliable isolation of short-circuit faults in photovoltaic (PV) storage and charging DC microgrids. However, the main switch typically experiences high current and voltage stress during fault isolation, thus challenging the safe operation of the SSCB. Hence, a novel SSCB topology based on a normally-on silicon carbide (SiC) junction field-effect transistor (JFET) is proposed, which can achieve fully zero-current turn-off for both the main and auxiliary switches. During a short-circuit fault, an LC resonant circuit injects a reverse pulse current into the SiC JFET main switch to achieve zero-current turn-off, while a metal-oxide varistor (MOV) branch absorbs the fault current flowing through the SiC metal-oxide-semiconductor field-effect transistor (MOSFET) auxiliary switch, thereby facilitating the zero-current turn-off of the SiC MOSFET. Subsequently, the operating characteristics and design considerations for key components, including the inductor, capacitor, and MOV, are analyzed. Finally, a 375 V/63 A SSCB prototype is constructed and validated. Experimental results confirm that the proposed topology achieves zero-current turn-off for all the switches when interrupting a 260 A fault current, thereby significantly enhancing the interrupting performance and energy efficiency of the SSCB in PV storage and charging DC microgrids.