Research on the system characteristics of radial offset based on double LCCL

Abstract

Wireless power transmission is one of the most active research direction which has a broad application prospect and huge development potential. A wireless charging system based on wireless power transmission consists of a transmitting coil at the charging station and a receiving coil in the electric vehicle. We calculate the mutual inductance between the transmitting coil and the receiving coil and analyze the trend of mutual inductance with the offset distance. Finally, we point out wireless charging system is very sensitive to an imperfect positioning of the vehicle. We think electric vehicles imperfect positioning is on a detuning state. So put forward a method that the operating frequency of the inverter is automatically adjusted to track the resonant frequency. Using the theory of reflection impedance, it is shown that the true reason for the decreases of transmission efficiency is that imaginary part impedance. It caused by the system offset. So the transmission efficiency of the system can reach a maximum when the imaginary part impedance is the smallest. Different migration of coil is verified by experiment; using MATLAB software for computer-aided analysis, we built an experimental platform of the 3.5 kW wireless charging. The experimental results verify the correctness of this view that the inverter tracks the output frequency by itself, which provides the theoretical basis for the further research in this field.