Modeling, simulation and experimental validation of solid media in capacitive wireless power transfer

Abstract

Capacitive wireless power transfer (CPT) employs an electric field to transmit energy through a medium. Air is the most often used and a well-understood medium. However, CPT can also bridge other solid media and even benefit from them as the dielectric properties of the medium govern the strength of the capacitive coupling. The parasitic elements of the coupling are influenced by the medium, in particular the leakage resistance. In this work, an analytical model is proposed that quantifies the leakage resistance losses in CPT systems for media. The model is validated by both finite element simulations and experiments on three different media: air, plexiglass and polytetrafluorideethylene (PTFE). As a result, at 1 MHz, the leakage resistance of plexiglass is 6 times higher than that of air while that of PTFE is 1.7 times smaller. This proves that a material with a large dipole moment generates larger losses in the medium which negatively affect system efficiency.