Design Methodology of Resonant Inductor in a ZVS Inverter

In a zero-voltage switching (ZVS) inverter, the resonant inductor is used to realize soft-switching aimed at dynamic loss reduction under high switching frequency conditions. For this purpose, the losses on the resonant inductor should be low enough to ensure a significant loss decrease for the whole system. Besides, ZVS inverters are usually operated at higher frequency than their hard-switching counterparts to allow size reduction of the passive components including the resonant inductor. This paper introduces a methodology incorporating new design rules for high efficiency and miniaturization of the resonant inductor with a gapped core in a ZVS inverter. High frequency winding losses generated by nonsinusoidal waveforms are discussed. Different winding schemes and positions of both barrel and flat windings are discussed and compared in order to find the most efficient and compact design. An inductor prototype utilized in a 100-kW ZVS inverter has been built. Both the finite-element analysis results and the experimental result are demonstrated to verify the design methodology.