Design and analysis of a decoupled three-phase coil array for inductive power transfer systems

Abstract

This article details the design process for a new three-phase coil array. All of the coils are made to be mutually decoupled from one another which is achieved by introducing a high reluctance path in the ferrite structure for mutual flux using an airgap in addition to controlling the coil overlap. Simulation and experimental results of a matched three-phase primary and secondary coupler, designed using the proposed novel decoupling mechanism, are presented to show that the high reluctance path introduced to decouple the coils still allows the main couplings to be maintained within an acceptable range. In contrast, negligible interphase couplings between coils in the primary or secondary were observed. Effective coupling, voltage and uncompensated power measurements are shown to verify the design is able to meet SAE J2954 WPT3 requirements. Finally, the leakage magnetic flux density, simulated under WPT3 conditions, shows that its RMS value remains significantly less than 27 µT at a 800 mm distance from the centre of the secondary coupler.