Multi-Frequency Pulse Width Modulation Control Strategy for Multi-Load MCR WPT System with Single Transmitting Coil

In multi-frequency multi-load magnetically coupled resonant wireless power transfer (MCR WPT) system, multiple inverters are usually employed to respectively provide a single frequency excitation voltage, and then a multi-frequency excitation voltage can be obtained through superposition methodology. However, the system still has the limitation due to complicated architecture and bulky volume. In this paper, only one single-phase full-bridge inverter is adopted in multi-load MCR WPT system, and a multi-frequency pulse width modulation (MFPWM) control strategy is proposed to integrate multiple frequency components into the single-phase inverter. In view of different excitation voltage characteristics, the unipolar and bipolar strategies are proposed respectively, along with the corresponding algorithm. The differences between the two control strategies in the modulation ratio range and harmonic content are discussed in detail. Finally, a hardware platform is built for experimental verification.