Active Clamp Zero Voltage Switching Multiple Output Flyback Converter with Voltage Doubler

Abstract

This paper proposes a multi output zero voltage switching flyback converter topology with actively clamped switch and voltage doubler circuit. Flyback is the most popular topology for isolated power supply. It can provide multiple isolated outputs with a single switch and has lesser number of component counts. But it suffers from major drawback of high switch current stress high eddy current loss in the air-gap area, a large transformer core, and potential EMI problems. Now a day the latter is overcome by soft switching commutation techniques zero voltage switching (ZVS) or zero current switching (ZCS).But the device still suffers from excessive voltage stress. To triumph over these shortcomings an active clamp flyback converter is proposed. Here the active clamped switch introduced is turned on at zero voltage, this action discharges energy from active clamp capacitor to transformer leakage inductance that is then used to discharge capacitor across the switch thus bringing down voltage across the switch to zero before turn on. The capacitor also acts as clamp that avoids excessive voltage ringing across the switches. The proposed converter has a voltage doubler rectifier in the secondary. So no dissipative RC snubber across the diode is needed and thus high efficiency, low noise output voltage can be realized. The operating principle and analysis of proposed converter are discussed in this paper in detail. The closed loop simulation with fuzzy logic controller is also presented and the analysis of the converter in terms of efficiency and regulation are analysed in detailed.