Analysis and Implementation of a Bridgeless Sepic AC/DC Converter with Power Factor Correction and Extended Gain

In this paper, a bridgeless Sepic AC/DC converter is proposed. The absence of an input rectifier bridge can reduce the conduction loss and the proposed topology separates the input PFC current and output current, which reduces the switch current stress and improves system thermal management compared with the traditional Sepic converter. In addition, the switches in the proposed topology all have semi-soft switching function to reduce the switching losses. Furthermore, the proposed converter has an output voltage multiplier stage. Based on the circuit analysis, a feasible control scheme is developed to achieve better input current shaping and output voltage regulation. Finally, a prototype system is constructed and the control scheme is implemented using DSP TMS320F28335. Both simulation and experimental results verify the validity of the proposed bridgeless Sepic AC/DC converter and the feasible control scheme.