Megawatt GTO-inverter with three-level PWM control and regenerative snubber circuits

Abstract

Regenerative turn-on and turn-of snubbers for a three-level PWM inverter using gate turn-off thyristors (GTOs) are analyzed and discussed. Problems encountered in high-power GTO inverters, namely, trapped energy in the snubbers and switching losses, are discussed. The circuit configuration and operation are described and a comparison with a two-level inverter is made. Experimental results from the operation at reduced voltage of a 4 MVA phase-leg circuit are presented.<>