Design of a Universal Inductive Charger for Multiple Electric Vehicle Models

Inductive power transfer technology has become a popular solution for battery charging of electric vehicles (EVs). However, problems such as varied magnetic coupling caused by coil misalignment still limit its practical applications, by safety and stability issues. Meanwhile, the growing market of EVs asks for a universal charger for various models. This paper presents the design process of a universal inductive charger (UIC) for EVs. The proposed UIC is capable of adaptively providing a constant or controllable charging voltage to various EVs, with a wide range of varied magnetic coupling between the transmitting and receiving coils. With a series-connected LC circuit, zero-voltage switching of the primary dc-ac inverter is universally realized in every charging cycle. A simple yet effective control method based on the frequency variation is used to automatically select the optimal frequency in different coupling conditions and adjust the frequency during the charging process. The design of the charging interface is also optimized with higher efficiency and power-transfer capability. Simulations and prototypes validate that the proposed UIC is accurate, robust, and applicable.