Voltage mode control of improved bridgeless flyback rectifier with bidirectional switch for adapter applications

Abstract

This paper introduces voltage mode control of flyback rectifier with bidirectional switch. The proposed control scheme employs an outer voltage feedback loop, which maintains the output voltage as constant. Conventional flyback rectifier is the combination of a diode bridge rectifier and a flyback converter. In order to obtain a highly efficient flyback rectifier with fewer losses an improved flyback rectifier is introduced. Here, two switches are connected in back to back to establish the bidirectional switch element, which will conduct both in the positive and negative half cycle of the ac input voltage. The transformer with dual output windings with a diode in each winding reduces the current stress across each diode. New topology adds an extra switch in the primary side and a diode in the secondary side. This converter has the applications in battery charger. Higher efficiency and minimal component is the major feature of external power supply. Improved bridgeless flyback rectifier only introduces a switch with common gate drive, a diode and an additional winding in the secondary side. Thus the weight of the converter is not affected with these additional components. Voltage mode control of flyback rectifier is suitable for obtaining a constant output with a varying input. Design and simulated waveforms are added in this paper for an output rating of 20V/1.5A.