In this paper, a coupling coil structure suitable for wireless charging of electronic equipment is designed. The coil is designed with PCB. The structure comprises an 8-shaped receiving-transmitting coil and two relay resonance coils on the same plane. When multiple transmitter coils are arranged in a row, the mutual inductance remains relatively constant during the offset process of the load coil, which can effectively reduce the power fluctuation during the charging process. Three-dimensional finite element simulation analysis and experiments were performed on the system under the conditions of alignment and offset，Experimental results show that when the coils are well aligned, the proposed WPT system can achieve a peak efficiency of 92.7%

wireless power transfer,wireless charging for mobile devices,power transfer efficiency,Magnetic coupling structure,PCB coil