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

Local overheating and airgaps magnetic leakage are severe due to the distributing inter-tile airgaps in wireless power transfer (WPT) ferrite pads. In this paper, a thermal-magnetic multi-objective optimization function (MOF) is proposed to evaluate and mitigate the thermal-magnetic deterioration caused by the distributing airgaps. The effects of the airgaps 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 airgaps width. An interesting range can also be found by using the proposed MOF strategy. When the airgaps width within the range, the gap thermal-magnetic problems can be mitigated effectively. Subsequently, a full-scale prototype with 11.1kW at 85kHz is fabricated to validate the effectiveness of MOF strategy and the accuracy of evaluation. The WPT pads with optimized airgaps achieve an excellent comprehensive performance which is superior to that without the optimization.