Boost and Buck topology based single phase AC-DC converters with low THD and high power factor

Two topologies of single-phase Buck and Boost AC-DC converters are 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 each of the Boost and Buck conversion mode to get step-up or 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.