Ferrite Pads Gap Thermal-Magnetic Evaluation and Mitigation for 11.1 kW Wireless Power Transfer

Local overheating and airgap magnetic leakage are severe due to the distribution of inter-tile airgap in wireless power transfer (WPT) ferrite pads. In this article, a thermal-magnetic multi-objective optimization function (MOF) is proposed to evaluate and mitigate the thermal-magnetic deterioration caused by the distributing airgap. The effects of the airgap on temperature and leakage distribution are analyzed based on the magnetic-thermal coupling finite element method (FEM) simulation. It is found that the trend of the local temperature is opposite to that of the magnetic leakage following the increase of the airgap width. An interesting range can also be found by using the proposed MOF strategy. When the airgap width is within the range, the gap thermal-magnetic problems can be mitigated effectively. Subsequently, a full-scale prototype with 11.1 kW at 85 kHz is fabricated to validate the effectiveness of the MOF strategy and the accuracy of evaluation. The pads with optimized airgap achieve greater comprehensive performance than that without the optimization.