A Relook at the ZVS of Power MOSFETs and an Improved Modeling Approach for ZVS Analysis in Power Converters

Zero Voltage Switching (ZVS) is revisited in this paper using a non-linear voltage-dependent device capacitance model to analyze the ZVS transitions. The proposed non-linear capacitance model is compared with the traditional charge-equivalent and energy-equivalent device capacitance models to analyze the equivalent circuits during the switching transitions. A numerical approach is adopted to solve the non-linear circuit equations during the switching transitions. A Phase Shifted Full Bridge (PSFB) converter is used as an example for showcasing the benefits of the proposed ZVS analysis. Furthermore, an H-bridge circuit is implemented in the laboratory, and is used to capture the switching transitions under ZVS and partial hard-switching conditions. The hardware results are in excellent agreement with the model predictions and are used to validate the accuracy of the proposed model and showcase the superiority of the proposed model over traditional models.