New Bridgeless DCM Sepic PFC Rectifier with Low Conduction and Switching Losses

New bridgeless single-phase ac–dc power factor correction (PFC) rectifier based on Sepic topology is proposed. The absence of an input diode bridge 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 Sepic PFC converter. The proposed topology is designed to work in discontinuous conduction mode (DCM) to achieve almost unity power factor in a simple and effective manner. The DCM operation gives additional advantages such as zero-current turn-on in the power switches, zero-current turn-off in the output diode and reduces the complexity of the control circuitry. The proposed rectifier is theoretically nvestigated. Performance comparisons between the proposed and conventional Sepic PFC rectifiers are performed. Simulation and experimental results are provided for a design example of a 65W/48-V at 100-Vrms line voltage to evaluate the performance of the proposed PFC rectifier