Experimental verification of coil rotation and phase‐shift control for enhancing wireless power‐transfer efficiency

Abstract Wireless power transfer (WPT) technology offers a promising solution for powering electronic devices without a physical connection. However, achieving high power‐transfer efficiency (PTE) while minimizing electromagnetic interference (EMI) remains a critical challenge, especially for flexible and unrestricted device positioning. This study explores the use of coil rotation and phase‐shift control to optimize the PTE by adjusting the transmitter (TX) coil orientation and phase shifts. Analytical expressions based on the Neumann formula are employed to derive the mutual inductance between two coaxially aligned coils with varying receiver (RX) coil orientations. A prototype magnetic resonance WPT (MR‐WPT) system is developed to validate the feasibility of the proposed efficiency enhancement methods. The simulation and experimental results demonstrate that optimizing the TX coil phase‐shift and coil‐rotation angle can maximize the RX voltage and improve the PTE by approximately 30%, while also reducing EMI levels.