A Comparative Study of Different Compensation Topologies for Capacitive Power Transfer

Capacitive power transfer (CPT) is an alternative method for wireless power transfer (WPT) which has started to draw wide attention. Compensation topologies play significant role in improving the power transfer performance of a CPT system, so many different topologies have been proposed and investigated. This paper presents a comparative study of six compensation networks, namely single L, double-sided LC, LCL, LCLC, CLLC, and LCLC-LC for CPT systems. Based on the first five topologies that are already utilized in CPT systems, a new LCLC-LC topology is investigated in this research. The advantages and disadvantages of these compensation topologies are summarized by analyzing their equivalent circuit models, power transfer characteristics against the load, coupling, and frequency variations. It has found if the series equivalent resistances are ignored, all these five topologies can be designed to achieve constant voltage or constant current output against load variations under fully tuned conditions. However, their output power changes with coupling variation. The steady state analysis of the impedance transformation and voltage or current source characteristics has shown that the double-sided LC topology can be tuned to achieve a constant output voltage against both coupling and load variations.