Soft-switching modulation strategy based on hybrid control for three-phase wireless power transfer systems

A hybrid control strategy is proposed for a SS compensated three-phase wireless power transfer (3P-WPT) system, which realizes full zero-voltage switching (ZVS) operation of the converter during the entire charging process of a battery. First, a mathematical equivalent model of 3P-WPT is established by fundamental harmonic approximation, the ZVS operation of the active bridge in the constant current (CC) charging mode is optimized by considering the relationship between the input impedance, operation frequency, and duty cycle. Consequently, an optimal modulation strategy featuring full ZVS operation is proposed for the constant current and constant voltage (CV) charging modes of 3P-WPT. Second, based on the NSGA-II algorithm, a mathematical model for the multi-objective optimization of coils is established, which aims for a high transmission frequency and power density. The parameters of coils are optimized accordingly. Finally, a 2 kW experimental prototype is built. Experimental results verify the effectiveness of the proposed control strategy, where the maximum efficiency is up to 90.26% at a full load.