Optimization of quasi-constant mutual inductance of asymmetrical coils with lateral misalignment in wireless power transfer system

—In the wireless power transfer system (WPT) via magnetically coupled resonance, the lateral misalignment between the transmission coil and receiving coil may affect the mutual inductance, then the transfer efficiency may be decreased, and the output power may be fluctuated, which lead to an unstable system. In this paper, a calculation method of the mutual inductance of an asymmetrical two-coil structure is presented. Based on the mutual inductance calculation method, an optimization method of quasi-constant mutual inductance is proposed. The key parameters of each coil can be obtained by using the proposed method. The mutual inductance can be kept constant when the misalignment is changed. And the output voltage and efficiency are also nearly constant with different misalignments. Finally, the setup of the asymmetric two-coil WPT system via magnetically coupled resonance is designed. Calculation, simulation, and experimental results validating the proposed method are given. © 2019, Electromagnetics Academy. All rights reserved.