Novel Two-Stage AC-DC Power Converter with Partial Single-Stage Power Processing

AC-DC power conversion is typically implemented with two converter stages: an AC-DC boost converter stage followed by a zero-voltage switching (ZVS) pulse-width modulated (PWM) full-bridge converter stage. An active auxiliary circuit is often used to reduce switching losses in the first-stage converter. The use of such a circuit to transfer a portion of the input power directly to the output of a two-stage AC-DC converter is investigated in the paper. Such direct power transfer (DPT) allows a portion of the power from the input to be processed only once, instead of twice, thus reducing the losses and the current stresses of the second-stage DC-DC converter. In this paper, the basic operating principles of the converter are explained, the features of the first-stage AC-DC boost converter are stated, and a set of guidelines for the design of the converter are given. The feasibility of the proposed converter is confirmed with experimental results.