Transmitter Coil Design for Multi-load Wireless Power Transfer Systems

This paper presents the design of a transmitter coil with an interleaved structure for multi-load wireless power transfer (WPT) applications covering a large charging area. The proposed coil achieves receiver positional flexibility, low electric field generation, and high efficiency. Analytical modeling of the coil magnetic field distribution, electric field generation, and power loss is presented and utilized in the coil design process. A prototype 0.5 m x 0.5 m transmitter coil is built and tested in a 6.78 MHz WPT system. The magnetic field is uniform across the entire charging are with less than 8% variation in amplitude. The overall system efficiency is 92.8% when loaded with two 50 W diode rectifiers.