Bridgeless PFC SEPIC rectifier with extended gain for universal input voltage applications

In this paper, a new single phase ac-dc PFC bridgeless rectifier with multiplier stage to improve the efficiency at low input voltage and reduce the switch-voltage stress, is introduced. The absence of an input rectifier bridge in the proposed rectifier and the presence of only two semiconductor switches in the current flowing path during each switching cycle result in less conduction losses and improved thermal management compared to the conventional full bridge topology. Lower switch voltage stress allows utilizing a Mosfet with lower R_Ds-on. The proposed topology is designed to operate in discontinuous conduction mode (DCM) to achieve almost a unity power factor and low total harmonic distortion (THD) of the input current. The DCM operation gives additional advantages such as: zero-current turn-on in the power switches and simple control circuitry. The proposed topology is compared with modified full-bridge SEPIC rectifier in terms of efficiency, total harmonic distortion (THD), and power factor. Detailed converter analysis, small signal model and closed loop analysis are presented. Experimental results for a 200 W/400 V_dc at universal line voltage range to evaluate the performance of the proposed bridgeless PFC rectifiers are detailed.