Reactance Compensation Control for Multiple-Receiver Wireless Power Transfer System with Coil Inductance Variations

In practical multiple-receiver wireless power transfer systems, the parameters of the coils and capacitors may vary from their designed values, thus preventing the reactance of the transmitter and receiver coils from being completely compensated. This paper proposes a control scheme for pulsewidth modulation controlled switched capacitors to compensate for the self-inductance variations of the coils and maintain the transmission efficiency. The proposed control scheme is implemented by completely separate closed-loops on each circuit to avoid wireless communication, which has been a major challenge in previous methods. The effectiveness of the proposed control scheme is verified by an experimental prototype consisting of a single transmitter coil and two receiver coils.