A Trigger Protection Circuit to Reduce Residual Voltage for Reversely Switched Dynistor

Reversely switched dynistor (RSD) is a two-terminal semiconductor switch with high critical switched current rising rate and peak forward current, and is triggered by the reverse pre charge current which is generated through the pre-charge capacitor and pre-charge circuit. If the trigger charge is not sufficient, the residual voltage can occur on RSD at turn-on, increasing the power loss and even leading to damage. In this study, a trigger protection circuit is proposed, to protect RSD from being damaged by high power loss caused by high residual voltages at insufficient trigger charges through connecting a trigger protection branch in parallel. In the experiments, the peak residual voltage of the RSD is reduced by up to 55.6% under insufficient trigger charges—from 1800 V to 800 V. Under this condition, the trigger protection circuit shunts the RSD current, reducing the RSD current rising rate and residual voltage. On the other hand, the trigger protection circuit also protects the RSD by preventing its turn-on during the discharge process under extremely insufficient trigger conditions. In this situation, the residual voltage of the RSD approaches the charging voltage of the main capacitor and the impedance of RSD branch is high, diverting nearly all the main current through the trigger protection branch, reducing the power loss of RSD significantly. More importantly, the shunting effect of the trigger protection branch to the main current is small at sufficient trigger charges. The trigger protection circuit provides the protection for the normal and safe operations of RSD in pulsed power applications.