Improved Capacitive Power Transfer With Non-Resonant Power Transfer Link Using Radio Frequency Push-Pull Inverter

In recent years, research on wireless power transfer and switched-mode power supplies with a capacitive coupling link has been on the rise. While many researchers investigate resonant coupling links, often resulting in tough requirements for the involved inductors, this article focuses on the elimination of all inductive components in the coupling link and the rectifier through the use of a non-resonant capacitive link. We propose a converter with a resonant single-ended push-pull inverter operating at radio frequencies of, e.g., 13.56 MHz to directly drive the non-resonant capacitive power transfer (CPT) link. The ability of the converter to operate at a high frequency and facilitate a significant voltage change across the link capacitors improves the power transfer characteristics of the system compared to previously published systems with a non-resonant capacitive link. Said combination is also beneficial for the transient behavior, parameter variation robustness, an easy design process, simplified drive requirements, and a predictable and limited capacitor voltage stress. The presented converter transmits 122.9 W across an effective link capacitance of 120 pF, leading to the highest input voltage-normalized power transfer to link capacitance value of 13.7 W/(nF \cdot \text{V} ) among previously published CPT systems with a non-resonant link.