High-Efficiency Mid-Range Inductive Power Transfer Employing Alternative-Winding Coils

A novel coil with alternative clockwise and counterclockwise winding has been proposed and employed to construct inductive power transfer (IPT) systems. After establishing the equivalent circuit of the proposed IPT system, the coil-to-coil, source-to-load, and optimum transfer efficiency are analyzed mathematically. Then, comprehensive expressions for accurate estimation of transfer efficiency of a realizable structure are deduced. Theoretical analyses indicate that it is not always mandatory to use extremely low-loss material to fabricate the coils for high-efficiency mid-range wireless power transfer (WPT) systems. To validate the proposed IPT system, a prototype is designed, fabricated, and measured. Good agreements are achieved between calculated and experimental results. It is demonstrated that the adoption of the present coil can enhance the IPT systems’ performance significantly. Compared with traditional IPT systems, the present system can operate properly without surplus and complex compensating networks. Further, an IPT system at 13.56 MHz employing proposed coils without any matching networks is designed, fabricated, and tested. This system is then used to drive a LED monitor wirelessly to demonstrate the feasibility of the proposed system in commercial applications. Owing to its design simplicity and demonstrated benefits, the proposed configuration endeavors to replace traditional approach to design high-efficiency optimized WPT systems.