A Single-Phase Class-E Direct AC-AC Converter Using Conduction Mode-Exchanged Pulse Density Modulation for Induction Heating System

This paper presents a new prototype of a single-phase class-E direct ac-ac converter for induction heating applications. In contrast to the multi-stage and traditional single-stage power conversion systems, the proposed direct ac-ac converter not only simplifies the topology of power conversion, but also enhances the efficiency, ffi ciency, soft-switching, and EMI performance, optimizing the overall system performance. This converter features a power control methodology utilizing the reverse conducting and reverse blocking modes of a bidirectional switch based on pulse density modulation, which is suitable for a wide range of soft switching and fixed frequency operations. The performance of the direct ac-ac converter is investigated by experiments using a 1.2 . 2 kW/56 / 56 kHz prototype, where the high-frequency load power regulation and power conversion efficiency ffi ciency are revealed as well as soft switching were verified. The practical effectiveness ff ectiveness of the power converter and power control scheme are evaluated.