Experimental research on characteristics of magnetic coupling resonance wireless power transfer system based on non-uniform low-frequency electromagnetic metamaterials

Abstract Low-frequency electromagnetic metamaterials (LFEMTM) can effectively improve the transfer efficiency of magnetic coupling resonance wireless power transfer (MCRWPT) systems. But it is difficult to accurately describe the electromagnetic characteristics of LFEMTM due to simulation and inversion errors encountered in practice. To address this issue, the paper proposes a 3×3 non-uniform LFEMTM array to enhance the transfer efficiency of a 6.78 MHz MCRWPT system. Differentiated electromagnetic response characteristics are constructed by adjusting the capacitance values of unit cells at different positions of the LFEMTM, and the optimal capacitance combination is obtained via experimental study. The experimental results demonstrate that the transfer efficiency of the system can be increased from 53.75% to 58.80% with the optimal non-uniform LFEMTM array, compared with the uniform array. Lateral offset experiments of the receiving coil reveal that the non-uniform array maintains a positive efficiency gain within the entire offset range. Its high-efficiency operating window (transfer efficiency > 55%) spans −80 mm to +60 mm, outperforming the uniform array significantly. The research outcomes are conducive to further enhancing the transfer efficiency of MCRWPT systems.