Research on Foreign Object Detection in WPT System Based on Power Spectrum Estimation of Transmitter Current

During the work of the wireless energy transfer (WPT) system, foreign objects will inevitably enter into the system. The intervention of metal objects and living objects makes the system deviate from the normal operating point and even lead to safety accidents. Therefore, foreign object detection is of great significance. The existing methods of foreign object detection usually require additional sensors, which are costly. However, this paper argues that the WPT system is capable of self-sensing. The system’s signal contains information about foreign objects, so there is no need to add additional sensors for foreign object detection. This paper studied the power spectral density curve of the transmitter current of the WPT system and found that the curve changed significantly when foreign objects entered the system. Accordingly, a foreign object detection system was designed. The method used the system’s own characteristics only, making the system have the dual functions of power transmission and foreign object detection at the same time. The proposed method in this study provides new ideas and inspiration for further developing foreign object detection in the WPT system.