Research on metal object detection of MCR-WPT system that allows transmisson coils to be misaligned

At present, the researches on metal object detection (MOD) of magnetically coupled resonant wireless power transfer (MCR-WPT) system are mostly based on the alignment of the transmission coils and large size metal object, and MOD will fail when the transmission coils are misaligned or the metal object is small. In this paper, the fundamental and 7-th harmonic component of the square wave voltage source are used for energy transmission and MOD, respectively. A double resonance and a single resonance structure are adopted by the transmitting (Tx) end and the receiving (Rx) end respectively, and the fundamental and 7-th harmonic component of the Tx current are large, and the 7-th harmonic component of the Rx current is extremely small. The conversion circuit is used to filter out the fundamental component of the induced voltage of the detection coil group, so that the Rx current has little influence on the filtered detection voltage, and the MOD allows the transmission coils to be misaligned. The 7-th harmonic component of the Rx current is used to increase the detection sensitivity, and a double-layer balanced detection coil set is designed to further increase the detection sensitivity. Finally, the co-simulation of electromagnetic field and circuit by Maxwell and Simplorer software verifies that the metal object can be effectively detected regardless of whether the transmission coils are aligned.