Multi-Frequency Identification Method for Foreign Object Detection in Wireless Power Tranfer Systems

In the operation of a Magnetic Coupled-Wireless Power Transfer system, (MC-WPT), an open strong magnetic field area is formed between the transmitting coil and the receiving coil. If metal enters the system during operation, significant temperature rise may occur due to the eddy current effect of the metal, which may cause safety hazards such as fire. Therefore, the system needs to have a Foreign Object Detection, (FOD) function to ensure the safe operation of the system. This article is based on the gain extremum method. According to the different effects of eddy current and magnetic effects on the gain of detection coils at different frequencies for different types of metals, a multi-frequency identification method is proposed to extract coil gains at multiple frequencies for analysis, which can identify the material type of the metal.