Design and Implementation of a High-Power Modular WPT System

Abstract

Comparing with refueling, charging speed remains a serious challenge holding back the development of the electric vehicles (EVs). Therefore, it is of significance to develop high-power wireless charging techniques. In this paper, the modular WPT system is investigated for substantially increasing the power level of a WPT system. The critical issue of the modular WPT system is the cross-couplings among different modules. The cross couplings form multiple power path in the system, which significantly complicate the output control. Meanwhile, there are plenty of variables that can be used for output control in a modular system, such as the input voltage amplitude of each module and the input voltage phase difference between every two modules. The effects of different control strategies on the overall performance of the system are studied. Then, a control strategy based on the predetermined input voltage phase angles and input voltage ratio among the modules is proposed. The output of the modular WPT system is controlled by adjusting the input voltages of all the modules, with fixed phase angles and ratio. Thus, the variables are reduced to one and a conventional PI controller can be adopted. A seven-module WPT system is carefully designed and implemented to verify the control strategy.