During the development of the pulsed forming units with rated storage energy of 100 kJ, a large number of thyristors used as the pulse switches were damaged. Based on the structure and equivalent circuit of the amplifying gate, the causes of the failure were found out by data comparison and analysis, fault component anatomy, process data investigation, gate resistance detection, turn-on time test and so on. The damage of thyristors was caused by the insufficient intensity of trigger current, which was rooted in the low operating voltage of the gate driving circuit. According to the conclusion of the turn-on time test, a method for determining design parameters of the strong trigger current has been obtained. The gate driving circuit was redesigned under the guide of the method. The new gate driving circuit has good performance, which entirely eliminates the hidden trouble of the failure.
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