Switching Frequency Control Strategy of Inverter for Multifrequency Multiload WPT System Based on Hysteresis Current Control

Due to the complexity of current variation of the multifrequency and multiload (MFML) wireless power transfer (WPT) system based on hysteresis current (HC) control, resulting in a wide range of switching frequency variation, high frequency, and high switching losses of the inverter. This article proposes a blocking delay switching frequency control strategy. Based on the design of blocking delay module, the time division blocking delay and full-time fixed frequency blocking delay control modes are investigated, which can reduce the inverter switching frequency fluctuation range and fix the inverter switching frequency respectively. First, the structure and working principle of the MFML WPT system based on HC control containing passive compensation network are analyzed. Second, the system switching frequency characteristics are analyzed. Third, for different system switching frequency limitation requirements, time division blocking delay control mode and full-time fixed-frequency blocking delay control mode are proposed. Finally, an experimental platform is built to verify the proposed control strategy, the experimental results show that the system switching frequency of different parameters is reduced to within 200 kHz and 180 kHz in the time division blocking delay control, and the system switching frequency is fixed to 150 kHz and 250 kHz in the full-time fixed-frequency blocking delay control.