Efficiency Optimization and Power Allocation of Omnidirectional Wireless Power Transfer for Multiple Receivers

Omnidirectional wireless power transfer to multiple devices has become a research hotspot due to its high spatial freedom and flexible design. However, this power supply method often faces the problems of high leakage flux and different receiver power requirements. This article studied the effects of currents of transmitting coils on transmission efficiency mathematically. A method of maximum efficiency tracking and power allocation for omnidirectional wireless power transfer to multiple receivers was proposed, and a mutual inductance identification method based on primary feedback is presented. Through the parameters identified by the primary side feedback, the current amplitudes and phases of the Tx coils were adjusted to achieve maximum efficiency, and the flexible power requirements of multiple devices can be realized. Finally, the above methods are experimentally verified. The two receivers can be charged with 58.8% efficiency and the power ratio can be precisely controlled from 0 to 100%, which is difficult for conventional method.