A large-capacity GTO inverter with low-loss snubber circuits

A large-capacity inverter using high-power gate turn-off (GTO) thyristors that can be used instead of a cycloconverter in AC drives is presented. With the techniques of multiple configuration and GTO series connection, the inverter capacity is increased effectively. High conversion efficiency is obtained by using low-loss snubber circuits for GTOs. It is confirmed that the low-loss snubber circuits using energy recovery units (ERUs) have good performance in pulse-width modulated (PWM) operation. High-energy recovery efficiency is obtained, especially in leading operation (turn-on operation when freewheeling diodes conduct). These snubber circuits have superior ability for clamping overvoltage at GTO turn-off. A 2750 kVA inverter with low-loss snubber circuits using high-power GTOs has been fabricated and evaluated.<
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