Design and optimization of the three-phase rail-type magnetic coupling structure for the electric vehicle wireless power transfer system

Compared with the single-phase wireless power transfer systems, the three-phase wireless power transfer systems have the advantages of large transfer power, high position offset tolerance, and small output ripple, etc., which have been widely used for high-power application. For a three-phase rail-type dynamic wireless power transfer system, the interphase cross-coupling mutual inductance, will lead to three-phase unbalance, difficult modeling and analysis. So, a new type of three-phase rail-type magnetic coupling structure is proposed and optimized. Firstly, a magnetic coupling structure for a three-phase rail-type dynamic wireless power transfer system is proposed. Secondly, the physical principle and mathematical tools are used to calculate the primary and secondary equivalent parameters of the system, and a fully decoupled equivalent mathematical model of the system is established. Thirdly, based on the model, the output characteristics of the system such as power and efficiency are analyzed. Finally, an experimental platform for a 1 kW three-phase rail-type dynamic wireless power transfer system is built to verify the theoretical analysis. The experimental results show that the magnetic coupling structure proposed in this paper can well solve the problem of system imbalance caused by interphase cross-coupling mutual inductance, and improve the power and efficiency of the system.