An LC compensated electric field repeater for long distance capacitive power transfer

This paper proposes an LC-compensated electric field repeater to extend the transfer distance of a capacitive power transfer (CPT) system. The repeater contains two metal plates, connected with an external capacitor and an external inductor. The plates are used to generate electric fields to transfer power. The external inductor and capacitor are used to resonate with the plates to increase the voltage levels. The repeater is placed between a transmitter and a receiver, which also contains metal plates compensated by an LC network. The repeater can increase the transfer distance of the CPT system without significantly influencing the system power and efficiency. In this paper, the capacitive coupler structure and dimensions are designed and simulated using Maxwell software. Considering all the capacitive coupling between plates, an equivalent circuit model is derived. The fundamental harmonics approximation method is used to analyze the working principle of the circuit. A 150W input power CPT system is designed as an example to validate the proposed repeater structure and compensation circuit topology. The system can achieve an efficiency of 66.9% from dc source to dc load, when the transfer distance is 360 mm and the repeater is placed between the transmitter and receiver.