Single switch buck boost AC-DC converter

Abstract

Two new topologies of single-phase Buck-Boost AC-DC converters with low input current THD and high input power factor are proposed and presented. Instead of using a single phase rectifier followed by a boost dc-dc converter, or using a bridge rectifier with two diodes and two switches, the rectifier’s input is chopped at high frequency during positive and negative cycles by a bi-directional switch in Buck-Boost conversion mode to get step-up/step-down ac-dc conversion. Total Harmonic Distortion (THD) of the input current of the proposed circuits with small input current filter is low. Input power factor and the efficiency of conversion of the circuits are high. The circuits exhibit such performance with variable loads at constant frequency switching. No additional control is required to achieve the advantages. Index Term- AC-DC power converters, bridge rectifier circuits, harmonic distortion, passive filters, active power filters, power supplies, power harmonics, rectifying circuits, harmonic standards.