Exploring the Impact of Roadway Materials on Dynamic Electric Vehicle Charging Based on Capacitive Power Transfer

Abstract

Wireless power transfer (WPT) opens avenues for contactless charging of various electronic devices. In particular, resonant capacitive power transfer (RCPT) can enable dynamic wireless charging of electric vehicles (EVs); however, the impact of roadway materials on RCPT systems has only recently begun being explored. This paper investigates the performance of CPT-based EV charging through an asphalt-based roadway, i.e., a lossy dielectric. More specifically, for the application where parallel-plate capacitor assumptions are held, it is shown that power transfer efficiency largely depends on the relative permittivity, including loss tangent, thickness of the dielectric layer, and loaded quality factor while being independent of both frequency and plate area. For more realistic RCPT scenarios with significantly lower coupling factors, system efficiency depends on the separation between the transmit resonator and dielectric layer with a tradeoff between coupling factor and dielectric loss. Moreover, with frequency dependent loss tangents, certain frequencies allow for higher efficiencies; the asphalt sample simulated in this study performed better at 6.78 MHz and 13.56 MHz than 1 MHz.