Design of a universal inductive charger for electric vehicles

Inductive power transfer technology has become a popular solution for battery charging of electric vehicles (EVs). For practical applications, various topologies, coil designs and control methods have been proposed. This paper presents the design of a universal inductive charger for EVs. Facing with the growing market with more and more EV models, the proposed charger can provide constant or controllable charging voltage to various EVs in different charging conditions. Based on the topology of a series-connected LC circuit, the Zero-Voltage-Switching (ZVS) operation of the primary DC-AC inverter is kept through charging, leading to higher efficiency. An effective control method is proposed to choose the optimal frequency in different conditions and adjust the frequency during the charging process. The design of the charging-pad is also analyzed, based on self- & mutual inductance and the current/power level. Simulations and a prototype are built to test the charger´s applicability.