Study on over-current protection of solid-state Marx generators

SiC MOSFETs with fast rising time and low switching loss have been gradually used in solid-state pulse generators. In this paper, aiming at protecting solid-state Marx generators from common over-current fault, the damage mechanism of SiC MOSFET is analyzed, and a new driving system with over-current protection is proposed. The drive system not only outputs drive signals with long pulse width, but also provides over-current clamping effect during the whole conducting process of the SiC MOSFET. Based on the relation between gate voltage of SiC MOSFET and drain current, the proposed drive circuit clamps the conducting current amplitude by pulling down the gate voltage of SiC MOSFET with a single sampling resistor and a pair of anti-series zener diodes. Experimental results show that the on-state impedance of the SiC MOSFET remains very low when the conducting current is low and consequently the gate voltage is slightly reduced. When an over-current fault occurs, the conducting current can be quickly clamped through the rapidly rising conducting impedance of the switch since the gate-source voltage is pulled down quickly. (authors)