SWITCHING CIRCUIT AND GATE DRIVE CIRCUIT FOR GATE TURN-OFF THYRISTOR

摘要

PURPOSE:To attain a high dielectric strength and a large current by connecting a capacitor between a terminal of a switching element and a source of a field effect transistor, providing a jump diode between terminals of the switching element and connecting a required number of capacitors with different time constant in parallel with the capacitor. CONSTITUTION:A cathode K of a gate turn-off thyristor(GTO) and a drain D1 of a MOSFETQ1 are connected and a switching drive terminal T3 connecting a switching drive circuit B to a gate G of the MOSFETQ1 is provided. Plural extraction diodes D connected in series are connected while the cathode connects to a source S1 of the MOSFETQ1 and connection terminals T4, T5 of a turn-on power storage capacitor C1 are provided across the diodes D and a series connection comprising of a capacitor C2 and a parallel connection between a resistor R2 and a diode DS2 connects in parallel with the capacitor C1. Thus, a high power voltage is controlled and the turn-off time is reduced.