Using an active rectifier on the secondary side to control improve efficiency in the dynamic wireless charging system for electric vehicles

Abstract

The transfer efficiency in a wireless power transfer system is maximized at optimum load impedance value. During the charging process, the load impedance value changes according to the state of charging of the battery which reduces transfer efficiency. This paper proposes a control method to improve efficiency in a dynamic wireless charging system for electric vehicles. Maximum transfer efficiency is achieved by controlling the load impedance according to the optimum load impedance value. However, in this systems, the optimum load impedance value depends on the position of the electric vehicle. Therefore, the paper also estimates the optimum load impedance value according to the position of the electric vehicle by the information measured on the secondary side. Furthermore, the secondary converter efficiency is also improved by used to the active rectifier. A 1.5kW dynamic wireless charging system is built in the laboratory to verify the feasibility of the proposed method. In the case of the receiver moving 30% misalignment, the transfer efficiency is increase by 6% compared with the case of fixed optimal load control. The system efficiency is achieved above 80%.