Fast Wireless Power Transfer for Multiple Receivers in Linear Topology

In a wireless power transfer (WPT) system in which multiple receivers are lined up on one side of a transmitter, the farthest receiver can experience difficulty receiving the required power from the transmitter because most of the power tends to be transferred to the nearest receiver. It is therefore necessary to find some means for providing sufficient power to charge the farthest receiver, in order to complete the charging of all the receivers within a reasonable time. In this paper, we propose two fast WPT methods: equal power distribution (EPD), and sequential power distribution (SPD). EPD allows all receivers to receive the same power by adjusting their load resistances and thus completing their charging at the same time, while SPD sequentially charges receivers in order according to location, and incorporates each charged receiver into the relay to assist with charging the next receiver. We analyze the charging times of the two methods based on equivalent circuit models and validate them using experiments by fabricating resonators. The analysis and experimental results show that the proposed EPD and SPD decrease the system charging time considerably compared with the conventional method in which there is no control.