Experimental Results of High-Efficiency Resonant Coupling Wireless Power Transfer Using a Variable Coupling Method

We experimentally demonstrate that the efficiency of wireless power transfer utilizing resonant coupling is improved by applying the matching condition. The 'matching condition' is extracted from an equivalent circuit model of a magnetically coupled wireless power transfer system. This condition is achieved by varying the coupling factor between the source (load) and the internal resonator. Applying this technique results in efficiency improvements of 46.2% and 29.3% at distances of 60 cm and 1 m, respectively. The maximum efficiency is 92.5% at 15 cm. A circuit model based on the extracted parameters of the resonators produces results similar to the experimental data.