Splitting Frequency Diversity in Wireless Power Transmission

Abstract

This paper investigates the methodology to create multiple frequency modes in a multiresonator system of one transmitter and multiple receivers based on the circuit theory. The multiple frequencies from natural responses of magnetic couplings could be obtained by determining the eigenvalues of a matrix equation. This potentially allows us to diversify transmissions to and from devices. Theoretical calculations and experiments show similar results of the multiple frequencies at given coupling conditions. Models of two, three, and four coils in straight line demonstrate the splitting mode in the spectral domain, which are validated by envelopes of signals. In measurements, three frequencies of 525, 625, and 695 kHz, and four frequencies of 495, 590, 670, and 755 kHz are achieved at the receiver for three- and four-coil models, respectively, when coils are equally distanced by 2 cm. When coupling coefficient of every adjacent coil in three-coil model is 0.2, aggregating the peak power at two and three splitting modes result in 28% and 71%, respectively, more power than that at resonance frequency. Similarly, with two, three, and four modes in four-coil model, the increases are 43%, 23%, and 33% with two, three, and four modes, respectively.