iBreaker: Intelligent Tri-mode Solid State Circuit Breaker Technology

Power electronics enabled DC microgrids mandate fast and low-loss protection against circuit faults. This paper discusses the major challenges and potential solid state circuit breaker (SSCB) solutions to address this need. It proposes a new SSCB methodology comprising four key elements: use of wide bandgap semiconductor (WBG) switches, tri-mode operation, combined digital and analog control, and universal hardware/software architectures. We report the design of a 380V/20A intelligent tri-mode SSCB (iBreaker) based on these design principles. We use SiC MOSFET and GaN HEMT in the iBreaker, which features three distinct operation modes: ON, OFF, and PWM Current Limiting (PWM-CL). While the conventional ON/OFF states allow the iBreaker to conduct normal load currents or interrupt fault currents, the PWM-CL state allows the iBreaker to gradually charge the input capacitors of electronic loads at a limited current level during load startup. The iBreaker can switch from the PWM-CL state to the OFF state if a true short circuit fault is detected. In the PWM-CL state, a variable frequency PWM control technique is proposed to optimally operate a buck converter for soft start and short fault detection. The new iBreaker is prototyped and experimentally verified.