Input switched single phase buck and buck-boost AC-DC converter with improved power quality

Two new topologies of single-phase AC-DC converter using Buck and Buck-Boost conversion with low input current THD and high input power factor are proposed. 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 single bi-directional switch to get step-up/step-down ac-dc conversion. Total Harmonic Distortion (THD) of the input current of the proposed circuit with small input current filter is low. Input power factor and the efficiency of conversion of the circuit are high. No additional control is required to achieve the advantages.