Design and Analysis of Flexible Capacitive Power Transfer With Stable Output Capability

Abstract

This paper presents a novel flexible capacitive power transfer (CPT) system, which has stable output capability when the coupler is deformed. To obtain the flexible coupler structure, the copper foil with the features of light, thin, and cost-efficiency is employed to form the flexible capacitive coupling. To achieve stable output capability, the frequency band selection method and the frequency splitting characteristic are deduced, which indicates that if the system works on optimized natural resonant frequency, moderate deformation of the copper foil coupler could have negligible effects on output power and efficiency. Furthermore, the finite-element analysis (FEA) is employed to simulate the variation of electric field distribution in the flexible coupler. Finally, a prototype is constructed in the laboratory. The copper foil coupler with 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thickness and the dimension of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$30\times 16$ </tex-math></inline-formula> cm is adopted, which can achieve more than 147 W power transfer for a 100 mm air gap with the efficiency over 86%. When the bending displacement is within 40 mm, the fluctuations of received power and efficiency are less than 3.6% and 3.1%, respectively. The measured results validate the feasibility of the proposed CPT system for being applied in flexible scenarios.