The Recognition and Control of Nonideal Soft-Switching Frequency for Wireless Power Transfer System Based on Waveform Identification

Nonideal frequency problems can occur in a wireless power transfer system due to multiple soft-switching frequencies and frequency bifurcation. To make the system work at an ideal frequency with high-power transfer capability and efficiency, a method based on waveform identification is proposed. First, the space state model of a SP type WPT system is built, and the waveforms at ideal and nonideal working frequencies are obtained based on the stroboscopic mapping theory. Second, according to the characteristics of these waveforms, the swing door algorithm is improved by waveform distortion rate and fast Fourier transformation, which is used to recognize nonideal waveforms. Then, a control strategy based on “online self-determined optimization” is proposed to deal with the problem. Finally, the results of simulation and experiments show that the method proposed in this paper can identify the waveforms at nonideal frequency and find an ideal working frequency for the WPT system.