Half-wave quasi-resonant flyback converter using a GTO

Abstract

Resonant power supplies incorporating an inverter in which the semiconductor switches maintain sinusoidal oscillation in an LC network can offer very high efficiencies. Furthermore, electromagnetic interference, radio frequency interference and mains borne pollution are much reduced compared with square wave switching. Unfortunately a higher voltage rated switch is required which is capable of the high frequencies required and low loss. The recently developed high speed Gate Turn-Off thyristor could provide a viable solution to the above requirements. This paper outlines the design and construction of a half-wave quasi-resonant flyback converter using a GTO at a nominal maximum operating frequency of 60 kHz. The power supply has an output of 500 watts at 60 volts. A full description is given of the circuit analysis, the design procedure used and results of a computer simulation of the prototype design using the computer simulation package PSPICE. Practical waveforms are given illustrating the operation of the circuit and emphasis is placed on the voltage and current of the switching device and the input current taken from the supply.