A Multilayer PCB Coil for Self-Resonant Wireless Power Transfer Systems

This article presents an innovative printed circuit board (PCB) coil for self-resonant wireless power transfer (SRWPT) systems. Parasitic capacitance between adjacent coil layers is used for compensation, allowing the elimination of physical capacitors normally used in the traditional RWPT systems. Multilayer design that connects multiple PCB coils in parallel is implemented to reduce the resonant frequency. Through applying track-width-ratio and track-gap-ratio, the ac resistance of the proposed PCB coil is significantly reduced, and the proposed SRWPT system achieves a high-efficiency accordingly. The equivalent circuit and theoretical models of inductance and capacitance of the proposed PCB coil have been established. Finite element method is employed to optimize the coil and simulate its performance. A SRWPT system based on the proposed coil is established, and experimental tests have been conducted to study its performance. The results show that the proposed system achieves a resonant frequency below 150 kHz, a coil-to-coil efficiency of 94.7%, and a high-quality factor of 123.