Dual-Frequency Metal Object Detection Based on SPWM Control for Wireless EV Charging System

Metal object detection (MOD) is an essential auxiliary function for wireless electric vehicle charging (WEVC) systems. However, current systems suffer from poor independence, low detection sensitivity, and failures at single detection frequencies. To this end, this article proposes a dual-frequency metal object detection (DF-MOD) technology based on sinusoidal pulsewidth modulation (SPWM) control for WEVC systems. The article first introduces the system structure and working principle, then establishes an equivalent model of the DF-MOD and analyzes its operational characteristics. Subsequently, the parameters for the main circuit and the filter circuit are designed to further enhance the detection sensitivity and anti-interference capability of the DF-MOD system. Finally, a system experimental platform is constructed to verify the feasibility and superiority of the DF-MOD technology controlled by SPWM in WEVC systems. The results indicate that the system achieves independent operation from the WEVC systems and improves detection sensitivity for 40x40 mm copper plates, aluminum plates, iron plates, and ferrite plates by 7.56%, 5.59%, 5.36%, and 16.82%, respectively, compared to single-frequency detection. Additionally, it achieves blind spot-free detection across the entire area.