Protection scheme of a charging and discharging system for a 500 kJ capacitor bank

Pulsed power systems consist of a capacitor bank, an isolated high-voltage charging power-supply, high-current bus-work for charging and discharging, and a control system. In such pulsed power systems, the operating-lifetime of the capacitors is closely dependent on the voltage reversal. Hence, most capacitor-discharging systems include crowbar circuits. The crowbar circuit prevents the capacitor recharging with reverse voltage. Usually, it consists of crowbar resistors and high pulse-current diode-stacks connected in series. The requirements for the diode-stacks are fast-recovery time and high-voltage and large-current ratings, which results in the high cost of the pulsed-power system. This paper presents a protection scheme of a charging and discharging system of a 500 kJ capacitor bank using a low-cost crowbar circuit and safety-fuses