An Inverter Topology for Wireless Power Transfer System with Multiple Transmitter Coils

This paper presents an inverter topology for a wireless power transfer (WPT) system that is intended to reduce the component counts and complexity of the conventional excitation circuit for multiple transmitter coils. The proposed inverter topology requires only (n+2) power switches, where n is the number of transmitter coils. An excitation of a proper transmitter coil pattern with regard to the receiver coil position is determined. The output voltage can be regulated through the primary-side control by adjusting the duty cycles of the inverter switches. A detection method of the receiver coil position is presented using the detection switches on the secondary side. The detection algorithm is based on the reflected impedance knowledge and requires only a current sensor on the primary side. A proper transmitter coil pattern is energized to ensure maximum transfer efficiency throughout the operation. The proposed system is experimentally validated on the created 500-watt WPT multi-coil system. After the receiver coil is placed in a designated area, the proper transmitter coil pattern can be automatically selected and energized. The output voltage can be regulated to a desired value under the typical operation conditions, including load change.