Efficiency optimizing and load matching analysis for the weak-coupling wireless power transfer system using a repeating coil

In order to improve the distance, power, and efficiency of power transfer in wireless power transfer system under the weak coupling condition, a 3-coil weak coupling power transmission model was created. A new match adjustment method of the Impedance network is raised based on the usage of impedance transformation of the relay. Adjusting the distance of the coil gives the maximum efficiency on the premise of constant load; lastly, an experiment system with PCB coils at frequency of 6.78MHz was designed. The effect of the impedance transformation of the repeating coil has been verified through simulations and measurement. The experimental results are consistent with the theoretical calculations throughout the experimental.