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

Abstract

In recent years, research on Wireless Power Transfer and Switched-Mode Power Supplies with a capacitive coupling link has been on the rise. Whereas many researchers investigate resonant coupling links, often resulting in tough requirements for the involved inductors, this paper 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 link. The ability of the converter to operate at a high frequency and to 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‧V) among previously published capacitive power transfer systems with a non-resonant link.

General Design Method of Bilateral Γ-Compensation Structure for EC-WPT System

“…Electric-Field Coupled Wireless Power Transfer (EC-WPT) technology solves various problems caused by the direct electrical contact of traditional wires [1][2][3]. Due to the shortcomings of traditional single-inductance compensation such as small transmission distance and low transmission efficiency, the superiority of bilateral Γ-type compensation network (LL, LC, CL or CC) gradually attracts the attention of scholars at home and abroad [4][5][6].…”