A Dual-Layer Receiver With a Low Aspect Ratio and a Reduced Output Fluctuation for EV Dynamic Wireless Charging

A dual-layer receiver with a low aspect ratio and a low output fluctuation is proposed in this article. It is composed of three parts: full-pitch coils, mixed-pitch coils, and a flat receiver core. In EV dynamic wireless charging system, power supply rails with alternately arranged poles, such as I-type, S-type, and N-type rails, have the advantage of narrow width, but they also show the main drawback of sinusoidal output fluctuation when they are mated with conventional double D (DD) receiver coils. To solve this problem, a dual-layer receiver is proposed in this article. Through the combination of full-pitch coils and mixed-pitch coils, the output fluctuation factor can be reduced from 100% to 29%. Compared with the conventional dual-DD receiver, the proposed receiver shows the following advantages. Full-pitch and mixed-pitch coils are not required to be dislocated in space so that the aspect ratio is reduced by 20%. In this way, the problems of too large receiver size and limited installation space can be solved, and the cross coupling between the receiver coils can be eliminated as well. Based on the theoretical analysis of the working principle of the dual-layer receiver, the output voltage expression of receiver coils is derived and the basic relationship between full-pitch and mixed-pitch coils is explored. Then, the influences of the mixed-pitch coil's symmetry and vehicle chassis on the system are analyzed, and the design principle of the proposed receiver is given. In addition, the dual-layer receiver is extended to multiple receivers through multiple cascades to further reduce the output fluctuation factor. Finally, a 10-kW prototype with ac–dc efficiency of 93.2% was built for experimental verification. The experimental results were consistent with theoretical analysis and simulation results, thus proving that the proposed receiver could reduce the aspect ratio and achieve the decoupling between the receiver coils under the premise of reducing the output fluctuation.