Modeling of Mutual Inductance Between Two Misalignment Planar Coils in Wireless Power Transfer

Mutual inductance is an important parameter for the design and optimization of the wireless power transfer (WPT) system. In this letter, a compact analytical model for mutual inductance of two coupled planar coil is proposed. The model is derived from Neumann's integral of constant current-carrying filament with a Taylor expansion approach. It can predict mutual inductance at various lateral and angular misalignments. The analytical results show a good agreement with the 3-D electromagnetic simulation results, and the maximum error for the mutual inductance remains less than 15.1%. An experimental setup has been built, and the results reveal the proposed model can predict the mutual coupling rapidly and effectively.

I. Introduction

Magnetic resonant coupling is an attractive solution to achieve wireless power transfer (WPT) [1]–[4]. With this kind of technology, a large amount of power can be successfully transferred from transmitting coils to receiving coils, but there are several important design aspects that require further investigation. One of the critical aspects is the prediction of the mutual inductance between the two coils, which contributes to the estimation and optimization of the wireless power link’s performance.