Mutual and Self-Inductance Variation in Misaligned Coupler of Inductive Power Transfer System: Mechanism, Influence, and Solutions

Abstract

This article focuses on the self- and mutual inductance variation of a coupler with ferrite in an Inductive Power Transfer (IPT) system. The mechanism of the variation was analyzed using the magnetic field splitting method, revealing that varying the reluctance leads to inductance variability. Additionally, the inductance variation trends were explored by Finite Element Analysis (FEA), based on which the input angle and voltage gain of an LCC-S type IPT system were calculated when coupler misalignment occurred. Then, an input voltage adjustment and frequency tracking compound control method was designed to neutralize the effect of inductance variability, which was validated by simulation. Finally, a prototype LCC-S type IPT system was fabricated. Experimental results reveal a 35.28% variation in self-inductance over the misalignment range, and the compound control managed to stabilize the output voltage and maintain the soft switching of the inverter with system efficiency remaining above 86% up to 94.27%. The proposed mechanism of inductance variation and compound control are instructive for solving the coupler misalignment problem in IPT systems.