Comparative Analysis of Frequency-Selective Wireless Power Transfer for Multiple-Rx Systems

In this article we describe a comparative study of the frequency-selective wireless power transfer (WPT) by considering two different configurations, Tx-Rx-Rx and Rx-Tx-Rx, in a multiple-receiver system. In this system, the receivers have different resonant frequencies and a transmitter can select a driving frequency to transfer power. Using an ECM, we analyze the power transfer efficiency (PTE) and the power distribution according to the variation of the driving frequency. We also find the achievable PTE (η
_max
) and the maximum power division ratio (α
_max
) in numerical terms for both configurations. The analysis and experimental results provide insightful information for understanding the effects of the arrangement of the resonators on η
_max
and α
_max
by comparison with the magnetic-resonant WPT, where the resonant frequencies of all the receivers are the same as the driving frequency. We find that the Rx-Tx-Rx configuration is generally more useful for distributing the power to the receivers than the Tx-Rx-Rx configuration, for both frequency-selective and magnetic-resonant WPT. In addition, the frequency-selective WPT enables a more adaptive power distribution than the magneticresonant WPT in the Rx-Tx-Rx configuration while maintaining η
_max
. We further verify that the results of the analysis are in accordance with the measured values, by means of experiments conducted in a variety of environments.