Optimization Study for Lateral Offset Tolerance of Electric Vehicles Dynamic Wireless Charging

Misalignment is a problem faced when electric vehicles work under the dynamic wireless charging mode using segmented transmitting coils. One kind of coil misalignment is coil lateral offset. In order to improve lateral offset tolerance, transfer efficiency and output power need to be stabilized. In this paper, first, the circuit model of a wireless power transfer (WPT) system is analyzed, from which mutual inductance is the major factor of the transfer efficiency decline caused by coils' lateral offset. The mutual inductance of two parallel square coils with lateral offset is analyzed. With the length and width of the transmitting coil being optimally designed according to the mutual inductance analysis, the mutual inductance of coils with lateral offset is optimized, and thus, transfer efficiency can be stabilized, and the system lateral offset tolerance is preliminarily improved. Moreover, in order to further enhance the lateral offset tolerance, the secondary-only resonant series-series (S-S) topology is adopted to stabilize the system output power. Finally, the optimal design with stabilized transfer efficiency is verified by the finite element simulation and the experiment with coils being scaled down. Due to the limitation of experimental conditions, the stability of output power is verified by simulation. (c) 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.