Three Phase Thyristor PWM Converter with Simultaneous Commutation Circuit

Abstract

In this paper, we propose a novel three phase thyristor PWM converter using a GTO for the commutation of the three phase thyristor converter. The main thyristor can be commutated simultaneously by turning off the GTO of the commutation circuit without consuming the energy in the snubber circuit. The proposed commutation circuit is very simple. It can be constructed by using a GTO and axial circuit components (two diodes, a reactor and a capacitor). When the GTO turns off, the capacitor operates as the snubber circuit for the GTO device so that soft-switching action can be obtained. The commutation energy can be transferred through the capacitor to the dc load without consuming the energy in the snubber circuit. Moreover, the additional voltage drop in the series diodes can be removed. So, the efficiency will be improved.