Design and testing of heavy pulse current switches based on photothyristors

This article presents the results of testing heavy pulse current switches based on photothyristors. Transient processes are considered that are observed in the semiconductor switch when the capacitor is discharged upon inductance and with a signal-shaping network with an inductor and crowbar diodes. The limit currents are found for the semiconductor structure, at which thermal generation peaks are observed in oscillograph records of direct voltage drop. The energizing of the photothyristor is analyzed. The need for forcing RC circuits to ensure fast and steady transition of the semiconductor structure to the conductive state is shown. The transient process observed at reverse recovery of photothyristors in the discharge circuit with inductance is considered. The need for snubber circuits to suppress pulse overvoltage is established. The particulars of the transient switching of current to the crowbar diodes and the generation of pulse overvoltages at reverse recovery of photothyristors are considered for a discharge circuit with crowbar diodes. The parameters of snubber circuits to suppress these overvoltages are determined. The validity of the accepted engineering solutions is confirmed by the results of tests at switching of a pulse current of up to 100 kA.