Hybrid Frequency Pacing for High-Order Transformed Wireless Power Transfer

This article proposes and implements a hybrid frequency pacing (HFP) technique for resonating a high-order transformed wireless power transfer (WPT) system with robust zero-voltage switching (ZVS). As a hybrid frequency modulation, the proposed HFP can efficiently tune the innate constant-frequency resonances of WPT. It can facilitate the pulsewidth modulated inverters to totally get rid of the high-frequency hard-switching while reducing the switching frequency and improving the system efficiency. For typical low-order boost WPT-based scenarios, the rectification effect may cause waveform distortions and involve a very low virtual capacitance, thus leading to great degradations on the ZVS and zero-phase-angle operation. In addition to achieve a load-independent constant voltage/current output, a high-order LCC network is deeply investigated to act as two-stage impedance transformations. By flexibly utilizing the rectification-caused virtual derivatives with the high-order transformations, it reliably contributes to a robust ZVS-HFP. The experimental system efficiency can be more than 91.5% with the full-range ZVS operation. Theoretical analysis and experimental results are both provided to verify the feasibility of the proposed ZVS-HFP for tuning the high-order LCC-transformed WPT system.