Comprehensive optimal load configuration method for misalignment tolerance of wireless charging system

Power level improvement is an important trend of wireless charging system (WCS) for electric vehicles. To improve the power level considering the misalignment tolerance of WCSs, a high-power WCS prototype with S-S topology is proposed based on the comprehensive optimal load configuration method. Firstly, the power and efficiency characteristics of S-S and LCC-LCC topology WCSs are compared in the unified circuit by equivalent conversion of the compensation topology, and the advantages of the traditional S-S topology for high-power WCS are evaluated by considering the cost, power density and reliability, etc. Meanwhile, a comprehensive optimal load configuration method that accounts for the statistical characteristics of the parking position is proposed, and the finite element method is used to calculate the efficiency characteristics under different load conditions. The results show that the proposed method achieves the highest expected efficiency, modestly improves the average efficiency, and mitigates the efficiency degradation resulting from the misalignment. Finally, a 22 kW S-S topology WCS prototype is designed and manufactured for experimental validation. The results show that, with the proposed comprehensive optimal load configuration method, the magnetic coupler efficiency of the WCS prototype is around 95% under different misalignment conditions. With 200 mm lateral misalignment, the efficiency of the prototype is 94.688%, only 0.464% lower than that under alignment condition. These results verify the effectiveness of the proposed method in enhancing misalignment tolerance. The achievement of this study can provide a theoretical basis for the misalignment tolerance improvement of high-power WCSs.