Using a Reconfigurable Bipolar Coil Structure as a Relay Coil for Cross Coupling Elimination and Interoperability of Wireless Power Transfer

In recent years, wireless power transfer (WPT) technology has developed rapidly. However, as the transmission distance increases, the system efficiency decreases. The long-distance and high-efficiency WPT system is the general trend, which can be realized by using relay coils, but the cross coupling presented in the coupling structure will lead to unstable system transmission. In this article, a reconfigurable bipolar coil structure is proposed, which solves the above problems while providing interoperability performance. By building an experimental prototype, the final experimental results indicate that the proposed coil structure not only possesses interoperability performance but also the voltage fluctuation rate at the output port is only 1.52% and 0.80%, compared with 13.89% for the conventional bipolar coil. This proves the absolute advantage of the proposed coil structure in eliminating the cross coupling. The experimental prototype achieves transmission efficiencies of up to 82.31% and 77.78% for the two states of the coil structure over a transmission distance of 200 mm.