Blind Zone Free Foreign Object Detection in EVWPT Systems via Dual-Comb Self-Resonant Coil

Foreign object detection is essential for ensuring the safety of wireless power transfer systems in electric vehicles. This letter presents a dual-comb self-resonant detection coil based on electric-field coupling, which achieves effective magnetic decoupling from the power coil and enables uniform detection coverage to eliminate blind zones. A transmission-line-based distributed parameter model is developed to characterize its impedance and self-resonance properties. An experimental platform incorporating quadrature demodulation is constructed, and measurements identify 17.33 MHz as the optimal operating frequency. Results confirm that a frequency shift exceeding 1.03 MHz indicates the presence of a living object, while a shift below 50 kHz corresponds to a metal object.