A More Accurate ZVS Criterion for Resonant Converters

Zero voltage switching (ZVS) is essential at the high frequency operation of resonant converter and the appropriate ZVS condition needs to be formulated to achieve the soft switching condition of power MOSFET devices. Conventionally, energy-balance is commonly used ZVS criteria for non-resonant converter, which has been directly applied to the resonant converter without verification. In this paper. the analysis has shown that the conventional energy based ZVS criterion is not so accurate as in the non-resonant case when it comes to the resonant converter. A more accurate ZVS condition using effective inductance energy is proposed in this paper. The analysis is verified by both LTspice simulation and experiment.