A new gate amplifier for high power GTO thyristors

Conventional gate control circuits have some defects, for example, the turn-on and turn-off time intervals cannot be made shorter because of the presence of the pulse transformers and/or the current limiting resistors with relatively large resistance, the relatively large power loss is generated in the current limiting resistor, the circuit is complicated and cannot be made smaller, and so forth. A gate amplifier for high-power GTO thyristors is presented, in which the energy-storage reactor and the FET switch with fast switched characteristics are employed to make the high gate current in the form of a sharp pulse. The proposed gate amplifier is analyzed, and its usefulness is confirmed by experiments. The performance characteristics of this gate amplifier are compared with those of the conventional one. As a result, it is clarified that this gate amplifier is superior to the conventional one in the performance of the gate-driving characteristics, power consumption, size, and weight