A foreign object detection coil array that does not affect the power transmission capacity of the wireless power transmission (WPT) system and has no detection blind spots was proposed in view of the problem that metal foreign objects falling into the charging area of electric vehicles affect the electrical characteristics of the system and generate eddy current heating in order to ensure the safety and reliability of the WPT system. The detection coil resonance circuit and control circuit were designed to improve detection sensitivity and accuracy. An electric vehicle WPT system experimental prototype with metal foreign body detection function was built, and the effectiveness and feasibility of the detection method through more than ten common metal foreign bodies were verified. The test results verified that the output voltage of the detection circuit had obvious changes by removing the cans, paper clips and coins from the detection coil. The size and material of various metal foreign objects were different, and the output voltage change rate was different. The effectiveness of the proposed metal foreign body detection method was verified.
Keywords:wireless power transfer
;
electric vehicle
;
eddy current
;
metal object detection
DU Kai, ZHU Guo-rong, LU Jiang-hua, PANG Mu-ye. Metal object detection method in wireless electric vehicle charging system. Journal of Zhejiang University(Engineering Science)[J], 2022, 56(1): 56-62 doi:10.3785/j.issn.1008-973X.2022.01.006
无线电能传输(wireless power transfer, WPT)技术[1-4]具有以下优点:1)无须人工干预,自动完成充电过程;2)能量发射和接收端无直接电气和机械连接;3)免受雨雪、霜冻、雷电等恶劣环境的影响. 该技术在消费电子、医疗设备和电动汽车等领域均已得到广泛的应用.
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