A Single-Stage Bridgeless AC/DC Resonant Converter with Distributed Switch Losses and Inherent Power Factor Correction Capability

This paper proposed a bridgeless AC-DC resonant converter with uniformly distributed switch losses. By replacing the bridge rectifier with a given configuration, the converter naturally achieves the uniform distribution at the primary switches in a full grid cycle, thus improving the reliability. The converter features a half-bridge structure on the primary side, with switches operating at a constant duty cycle of 50%. This layout maintains the clamp capacitor’s voltage at 2|vg|, enabling the use of a small film capacitor and obviating the need for a large one. Furthermore, it helps the converter achieve a unity power factor inherently. In addition, a semi-bridgeless configuration reduces the conduction losses of the input rectifier by half. An active resonant voltage doubler circuit with an AC switch is used on the secondary side. To achieve the desired results, controlling only the duty of an AC switch, making the control process simple and straightforward. All the switches of the proposed circuit are turned on with almost ZVS, and the AC switch is turned off with low voltage, thus further reducing the losses of the proposed converter and achieving the efficiency of 96.6%. We validate the results of the proposed AC-DC converter by developing a 444 W laboratory prototype.