Study on Overcurrent Protection of Magnetic Isolated Synchronized Driver for Marx Generators

Silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) are widely used due to their high operating frequency and low switching losses in solid-state Marx generators (SSMGs). As a result, overcurrent protection of SiC MOSFETs in pulse power supplies has become increasingly important. This article proposes a passive overcurrent protection driver based on the gate charge self-sustaining effect. This driver circuit enables synchronized output of multiple drive signals and also provides overcurrent protection without affecting the normal operation of SSMGs. The negative bias voltage can ensure the reliable turn-off of switches after overcurrent protection. Two common overcurrent faults including hard switching fault (HSF) and a fault under load (FUL) were analyzed. Experimental results show that replacing Zener diodes with TL431 considerably improves the response speed of the protection from 2 $\mu$ s to 500 ns. The overcurrent protection threshold can be adjusted by TL431, increasing the flexibility of the protection circuit. Once the overcurrent protection is triggered, the gate–source voltage of the switch will remain negative to ensure it stay in the off-state.