Objective As wireless power transfer (WPT) technology is increasingly deployed in scenarios such as electric vehicles, metallic foreign objects in the WPT area may cause local overheating and energy loss. Existing methods still suffer from poor edge/corner sensitivity, misjudgment due to fixed thresholds, and limited ability to extract position information. This work proposes a wireless power transfer-foreign object detection (WPT-FOD) method based on channel differential response and a dynamic-threshold corner-enhancement strategy, aiming to improve detection sensitivity, localization accuracy, and robustness without altering the overall coil layout.

Method A multi-channel detection coil array is designed, and the self-inductance disturbance response of each channel coil is modeled. A channel-difference mapping mechanism is introduced to build a 2-D sensitivity matrix to characterize spatial position correlation. A corner-enhancement algorithm is developed to weight and amplify the collaborative response of adjacent channels, and a dynamic threshold adjustment mechanism is integrated to adapt to varying interference levels. Validation is carried out on a self-built 64-channel FOD platform by moving a typical metallic foreign object across central, edge, and corner regions, and by conducting comparative tests under different interference intensities.

Result When a typical metallic foreign object moves to corner regions, the self-inductance disturbance of the detection coil increases from less than 0.02 μH to more than 0.06 μH, significantly enhancing the discrimination capability at corners. Under varying interference strengths, the dynamic threshold mechanism reduces the number of false positives from 13 to 2, demonstrating good environmental adaptability and stability.

Conclusion By combining channel differential response, corner enhancement, and dynamic thresholding, the proposed WPT-FOD effectively mitigates edge/corner blind spots and fixed-threshold misjudgment, while providing localization capability and robustness. It markedly improves the accuracy of metallic foreign object detection in WPT systems and offers a feasible path and method reference for the safe application and engineering deployment of WPT systems.