In order to better improve the compatibility of wireless charging devices, multi-frequency multiple-receiver wireless power transfer systems with a single inverter have attracted attention increasingly. However, how to regulate each load voltage is still a unique challenge in such system. To solve the problem, this paper proposes a regulation method combining multi-frequency modulation and proportional integral (PI) control. The multi-frequency modulation is based on delta-sigma modulation (DSM) principle and improved specific harmonic elimination pulse-width modulation (SHEPWM) principle. In proposed method, a hybrid multi-frequency modulator is designed to drive inverter to transmit multi-frequency power, which can not only make each receiver absorb power simultaneously, but also adjust load voltage of multiple receivers independently and continuously. Further, multiple PI controllers are applied to constitute a closed-loop controller, which achieves precise regulation and enhances the stability and dynamic response capability of system. With this method, just one full-bridge inverter supplies power to multiple receivers simultaneously, and the switching frequency is lower compared with other methods. Finally, the feasibility and superiority of proposed method are verified by theoretical analysis and experiments.

closed-loop control; delta-sigma modulation (DSM); specific harmonic elimination pulse width modulation (SHEPWM); wireless power transfer.