Output-Controllable Efficiency-Optimized Wireless Power Transfer Using Hybrid Modulation

This article proposes and implements an output-controllable efficiency-optimized wireless power transfer scheme using hybrid modulation. The key is to combine pulse frequency modulation (PFM) and on-off keying (OOK) modulation and to utilize feedback control. Among them, PFM is used for the output voltage regulation of the inverter to adjust the rectified output voltage on the receiver side, while OOK modulation is adopted to convert the load resistance to be close to the optimal resistance value so that the system efficiency can be effectively optimized. When the relationship between the input and output voltages reaches a ratio related to system parameters, it can be considered that the load resistance has reached the optimal state. Hence, the feedback output voltage is utilized to help convert the load resistance into an optimal value and only one voltage acquisition circuit is needed. In this article, theoretical analysis and practical experimentation (using the LED lamp as a nonlinear load and the 102-Ω resistance as a linear load) are both given to verify that the proposed scheme can help to maintain high system efficiency during the output voltage regulation process.