Interleaved SEPIC Power Factor Preregulator Using Coupled Inductors In Discontinuous Conduction Mode With Wide Output Voltage

A power factor preregulator (PFP) usually serves as the first stage of an active two-stage ac/dc converter in a variety of applications including inductive heating systems, wireless charging systems, and onboard chargers for plug-in electric vehicles. Conventionally, boost-type PFPs are utilized to regulate the dc-link voltage at a fixed voltage; however, a variable dc-link voltage can enhance the overall efficiency of the converters. In this paper, an interleaved single-ended primary inductor converter (SEPIC) with coupled inductors is proposed as the PFP stage for two-stage ac/dc converters. The converter is designed to operate in discontinuous conduction mode in order to achieve soft switching for switches and diodes. The directly coupled inductors are utilized to reduce the number of magnetic components and decrease the input current ripple. A 500-W interleaved SEPIC PFP prototype is designed to verify the benefits of this converter. The experimental results show that the converter can maintain high efficiency over a wide range of dc-link voltage.