Frequency Splitting in an LCLC Capacitive Wireless Power Transfer System for Electric Vehicle Charging

Abstract

Capacitive Power Transfer (CPT) systems present some advantages when compared to its inductive counterparts, being cost and weight the main ones. CPT technology has been mostly used in low power and short distance applications. However, recent studies have shown highly efficient electric vehicle (EV) chargers in the kW level employing this approach. Unlike inductive power transfer (IPT) systems, CPT for high power levels and large distance ranges has been less explored, and phenomena such as frequency splitting still require more detailed analysis, especially for promising topologies like those based on full-bridge inverters with double-side compensation networks. This paper evaluates the relationship between coupling factor and frequency splitting load power phenomena in an LCLC-compensated CPT system. It was found that a load power split occurs at low coupling factors, contrary to characteristics shown by other topologies. Therefore, determining the critical coupling factor to avoid the aforementioned issue is important to define the maximum plate distance at the charger design stage.