An efficient design of LC-compensated hybrid wireless power transfer system for electric vehicle charging applications

Abstract

Wireless power transfer (WPT) is the technology of transferring the electric power through a time-varying electric or magnetic field acting as a transmission medium. A combination between the inductive power transfer (IPT) and the capacitive power transfer (CPT) has been recently developed to benefit from the merits of both systems in order to realize high power transfer with high efficiency through large air gaps and misalignment distances. The output power capability of the existing designs is still limited and needs further enhancement. In this paper, a new hybrid inductive and capacitive wireless power transfer model is proposed, analyzed and simulated. The inductive part composes of a circular spiral coil integrated with a helical coil and supported with cross shape ferrite bars in order to enhance the magnetic coupling ability. The capacitive part consists of four cylindrically evacuated square plates compatible with the inductive part size to facilitate the combination process. Firstly, the system structure is designed using Maxwell-3D simulation tool, then an equivalent circuit model is derived in detail to explicate the working principle. Secondly, a 10.1 kW hybrid system is designed and simulated using MATLAB/Simulink and ANSYS/Simplorer. Excluding the inverter and the rectifier internal losses and considering only the AC losses of the coils represented in their parasitic resistance, a high resultant efficiency equal to 99.37% at a resonant frequency of 1 MHz is achieved. Generally, the results show that the hybrid system could perform better under different air gaps and misalignments than the inductive and the capacitive systems separately.