Multi-DoF wireless power transfer systems based on magnetic dipole coils with multiple receivers

To improve the degree of freedom (DoF), and the multi-terminal power supply capability of wireless power transfer (WPT) systems, multi-DoF WPT systems for multiple pickups based on magnetic dipole coils are proposed in this paper, which can simultaneously charge multiple receivers regardless of the position degree. First, the equivalent circuit model of the magnetic dipole coils is provided. The critical factors of the proposed multi-load systems are analyzed, such as transfer efficiency, power distribution, and optimal load. Second, a multi-load wireless power transfer system with equal transmitting (TX) and receiving (RX) coil is designed, and the misalignment tolerance of lateral and rotating occasions for the RX coils is discussed. In particular, a multi-load WPT system with miniaturized step-laminated receivers is implemented based on the magnetic dipole coils. Finally, experimental prototypes are established. The obtained results indicate that the output power for the equal dual-load WPT system can reach more than 78 W with a total efficiency of more than 80% under a transfer distance of length of the receiving coil winding. In addition, the output power of the non-equal four-load WPT system can reach 30 W with a total efficiency of 86%. The proposed systems provide practical guidance for the future development of multi-DoF WPT systems for use in portable devices, unmanned intelligent systems, and smart household applications.