Optimization of Circular Coil Design for Wireless Power Transfer System in Electric Vehicle Battery Charging Applications

In wireless power transfer (WPT) systems, the design of transmitter and receiver coupling coils plays an important role in power transfer. These coupling coils should be capable of transferring power over a large air gap in the order of 140 mm to 210 mm while providing good tolerance to coil misalignment in electric vehicle application. The coil must be designed considering the interoperability, size, weight of the pad, and coupling between the coils to achieve the maximum efficiency from the system. In this paper, circular coil design optimization for a 3.7 kW Type-1 wireless charger has been done by using 3D-Finite Element Method (FEM) analysis. In this work, the influence of change in vertical offset between the coils and misalignment on the critical design parameters such as coupling, quality factor, and mutual inductance is investigated. The number of turns in the coil and its placement optimization has been done. By taking available ferrite cores as a reference, the effect of different core parameters on the coupling coefficient and weight of the pads has been investigated along with flux shielding. Finally, a 450mm×450mm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$450\,\hbox {mm}\times 450\,\hbox {mm}$$\end{document} circular pad design is made for 3.7 kW output power. The measured and simulated results for the different vertical offsets and lateral misalignment is investigated.