A Self-Powered Bidirectional DC Solid-State Circuit Breaker Based on SiC JFETs for DC Microgrids

Solid-state circuit breaker (SSCB) has the advantages of fast switching response, no arc, and flexible control in dc fault clearance. The bidirectional power flow of dc microgrid requires SSCBs based on power devices with unidirectional turn-off capability to reliably clear faults at either end. Thus, this article proposes a self-powered bidirectional SSCB (BSSCB) without an external auxiliary power supply. First, a self-powered BSSCB topology of silicon carbide junction field-effect transistors (SiC JFETs) is proposed. Then, the turn-off process of the proposed BSSCB is analyzed in detail, where the effects of self-powered capacitors and voltage-clamping metal oxide varistors (MOVs) are considered. It reveals the influence rules and parameter design basis of these components on turn-off time and overshoot voltage. Finally, a BSSCB prototype is constructed and tested. The experimental results demonstrate that the proposed BSSCB can rapidly isolate short-circuit faults. Additionally, it can maintain a safe and stable self-power supply whether the short-circuit fault occurs on any side of the BSSCB.