Power-Transfer Performance Improvement for S-S Compensation IWPT System Based on Self-Adaptive Impedance Matching

Power-transfer performance has always been one of the main obstacles to restrict the widespread deployment of series–series (S-S) compensation inductive wireless power transfer (IWPT) system. Thus, the main objective of this article is to improve the power-transfer performance of system, which enables it to better meet the demand of different application scenarios. First, coupling coefficient and load equivalent resistance are selected, to reveal one of the reasons why it is hard to realize high power-transfer efficiency from a hardware perspective. Then, after considering the output characteristic of primary-side inverter in the system equivalent model, the effects of inverter on system stability, and the feasibility of realizing power-transfer performance improvement by inverter are studied, which mainly includes the interaction between digital time delay and coupling coefficient. Third, the mechanism of power-transfer efficiency limitation of conventional system is investigated based on impedance matching theory. Finally, to meet power-transfer requirements effectively and efficiently under the complicated and changeable system situation, a self-adaptive impedance matching tracking strategy is proposed. The experimental results validate the theoretical analysis and show that system with proposed control strategy can maintain a satisfactory power-transfer performance even under the perturbation of load and system parameters.