Design of high efficiency low frequency wireless power transfer system for electric vehicle charging

In this paper, a high-efficiency wireless power transfer (WPT) system based on magnetic resonant coupling is designed to operate at low frequency for electric vehicle charging. For simplicity, two coils wireless power transfer is proposed. Transmitter and receiver coils of WPT system are designed to improve quality factors and coupling coefficient. Effect of turns, coil radius, and misalignment on coil parameters and system performance are analyzed using three-dimension finite element method. Compensation circuit is designed and analyzed to achieve maximum power transfer efficiency. The effect of coupling coefficient value on system efficiency and resonance frequency is investigated. Input power, output power, and compensation capacitors voltage stress of the two compensation methods are analyzed and compared. Finally, the system performance is tested under different spacing and misalignment. Power transfer efficiency is more than 95% even under misalignment.