Operating Frequency and Natural Frequency Characteristics Analysis of MC-WPT Systems

In traditional magnetic coupling wireless power transfer (MC-WPT) systems, the combined use of magnetic induction, tuned circuits and resonant operating frequency has been a common theme for achieving the maximum transfer efficiency. However, that is not exactly true. By deeply analyzing the operating frequency characteristics and circuit natural frequency characteristics of transfer efficiency of MC-WPT systems, this paper discovers that: 1) the optimal operating frequency and optimal circuit natural frequencies for the transfer efficiency are two different concepts; 2) Only under certain parameters, is there an optimal operating frequency for the transfer efficiency, otherwise the transfer efficiency increases with an increasing operating frequency. Moreover, even if there is an optimal operating frequency for the maximum transfer efficiency, the optimal operating frequency is not equal to the circuit natural frequencies in the system; 3) With a fixed operating frequency, the transfer efficiency is maximized when the natural frequency of the receiver is equal to the operating frequency, regardless of the natural frequency of the transmitter. The simulation and experimental results have confirmed the validity of these conclusions.