Design of a Forward-flyback Converter Based Drive with Gate Voltage Limitation for a DC Circuit Breaker Using Normally-on SiC JFET

Normally-on Silicon Carbide (SiC) JFETs are considered promising switching semiconductor devices for solid state DC breaker due to their small on-resistance and robustness with short-circuit. In the self-power DC solid-state circuit breaker using normally-on SiC JFET, a very fast and reliable protection driver is required to generate a sufficient negative voltage to turn and hold off the SiC JFET. This paper proposes a forward-flyback converter topology for the protection driver. The converter will be activated whenever circuit breaker detects short-circuit faults by sensing the drain-source voltage of JFET and create a negative voltage applies to the gate of JFET. To avoid gate failure by over voltage at the gate of JFET, the output voltage of the forward-flyback converter is regulated using Primary Side Sensing technique. Experimental results show that the proposed protection driver can provide sufficient negative output voltage to turn off JFET and maintain this voltage in the permitted range.