An integrated single-stage AC/DC converter with ZVS active-clamping for universal line applications

Simple topology, high performance and low cost penalty are often the primary objectives in many low-power applications. In this paper, a novel single-stage AC/DC converter which dramatically reduces the devices count and circuit complexity is introduced. The converter integrates the function of input current shaping, tight output voltage regulation and zero-voltage-switching (ZVS) active-clamping. With a coupled primary winding, the rectifier diodes and the bulk inductor in the conventional PFC cell are eliminated in the proposed converter. By choosing appropriate turn-ratio of the windings, the voltage across the bulk capacitor can be effectively controlled, and the input current harmonics can be limited to meet IEC 61000-3-2 Class D specifications. The converter is analyzed and verified with 48 V/70 W output and the line input voltage range is from 90 to 260 V. It is shown that the power dissipated on two active switches can be kept around 1.82-3.18 W for universal line input voltages.