A Study on Magnetic Field Repeater in Wireless Power Transfer

It is shown that the distance of wireless power transfer is significantly increased by placing intermediate resonators (repeaters) between transmitter and receiver. The guidelines are provided to use the repeaters effectively. We first briefly review how the repeaters enhance the transfer distance. Next, the aspect of resonant frequency splitting is studied separately both for even and odd numbers of repeaters. The transferred power, efficiency, and output impedance phase are evaluated for each repeater configuration. These provide the guidelines to select the optimum repeater positions and numbers. We also propose and study a new kind of repeater which can be placed (biased) even in the vicinity of transmitter or receiver. This increases the flexibility in choosing the repeater position. The net effect of such biased repeater is approximately doubling the effective coupling coefficient between transmitter and receiver. Experimental results are provided to prove the concepts.