Efficiency Maximization Control and Voltage Regulation for Dynamic Wireless EV Charging Systems with Mutual Induction Estimation

Wireless Power Transfer has been proposed for electric vehicle charging applications to obviate problems associated with battery size, weight and cost. This paper proposes a control method to achieve maximum efficiency and load voltage regulation in such applications. The resonance frequency of the system is used as the optimum operating frequency and a DC-DC Buck converter is employed for tuning equivalent load resistance. Because the system optimum operating point depends on the mutual inductance of the transmitter and receiver coils, an estimation method is introduced to determine the inductance and the optimum operating point online. The control scheme adjusts the duty ratio of transmitter side inverter to fix the load voltage upon changes in the mutual inductance. This would be a cost saving solution since it does not use an extra converter.