A Power-Enhancing Complementary Coupling Integration Strategy for Misalignment-Tolerant WPT Systems

This article presents a complementary coupling integration method for an inductor-capacitor-capacitor-series-compensated wireless power transfer (WPT) system to improve the misalignment tolerance and power transfer capability. To this end, a compensation (Cx) coil formed by a long rectangular coil wound into a C-shaped structure is proposed. As a result, two multiples of the mutual inductance (MI) between the Cx and receiver (Rx) coils are added to the MI between the transmitter and Rx coils, providing the MI complement effect to increase the equivalent MI under both the perfectly aligned and misaligned conditions. A mathematical model based on the Delta-Wye network transform is developed to obtain the zero-phase-angle (ZPA) input and load-independent constant current (CC) output conditions. A 1-kW scaled-down WPT prototype based on the proposed method is built, and its performance is experimentally validated. The proposed system achieves 85.22% efficiency at 150-mm air gap and tolerates $\pm$200-mm $x$-, $y$-, and diagonal misalignments, $\pm$50-mm $z$-misalignment, and 20$^\circ$ angular misalignment with ZPA input and load-independent CC output as the load varies from 5 to 20 $\Omega$. In addition, the system performance is barely affected by the planar rotation misalignment.