A self-powered bidirectional DC solid state circuit breaker using two normally-on SiC JFETs

This paper reports self-powered, autonomously operated bidirectional solid state circuit breakers (SSCB) with two back-to-back connected normally-on SiC JFETs as the main static switch for DC power systems. The SSCBs detect short circuit faults by sensing the sudden voltage rise between its two power terminals in either direction, and draws power from the fault condition itself to turn and hold off the SiC JFETs. The two-terminal SSCB can be directly placed in a circuit branch without requiring any external power supply or extra wiring. A low-power, fast-starting, isolated DC/DC converter is designed and optimized to activate the SSCB in response to a short circuit fault. The SSCB prototypes are experimentally demonstrated to interrupt fault currents up to 150 amperes at a DC bus voltage of 400 volts within 0.7 microseconds.