Frequency splitting analysis of magnetically-coupled resonant wireless power transfer

Based on four-coil magnetically-coupled resonant wireless power transfer, this paper demonstrates, explains, and analyzes the frequency splitting phenomena with the circuit theory. Firstly, we build the complete and simplified models to describe the whole system. Then the frequency splitting phenomena are displayed and further explained by measuring and describing the amplitude-frequency and phase-frequency characteristics of the input impedance. Three related factors, i.e. the source internal resistance, the mutual inductance of the source coil and the sending coil, and the mutual inductance of the load coil and the receiving coil, are studied. Theoretical calculations and experimental results provide a sound basis for the explanation.