A single stage power factor corrected ac/dc converter

This paper presents a single stage isolated converter topology to achieve a regulated de output voltage having no low frequency components and a high input power factor. The topology is derived from the basic 2 switch forward converter, but incorporates an additional transformer winding, an inductor, and a few diodes. The proposed circuit inherently forces the input current to be discontinuous and ac modulated to achieve high input power factor. The converter's output is operated, in discontinuous mode to minimize the bulk capacitor voltage variations when the output load is varied. Analysis of the converter is presented and performance characteristics are given. Further, design guidelines to select critical components of the circuit is presented. Finally, experimental results on a 160W, universal input, 54Vdc output converter are given which confirm the high efficiency and high power factor features of the proposed topology.