Influences of Coil Radius on Effective Transfer Distance in WPT System

Yang Li,Quan Li,Wei-Hao Dong,Shan Jiang,Jia-Ming Liu,Xue-Li Liu,Xin Ni

doi:10.1109/access.2019.2937394

Abstract

The improvement of effective transfer distance is significant for wireless power transfer (WPT) via coupled magnetic resonances, with coil radius being the most important influencing factor. To study the relationship between effective transfer distance and coil radius, a model of WPT is established at first. Based on analyses of circuit and magnetic field, the influencing factors for effective transfer distance are obtained. Second, the models of WPT are constructed using software COMSOL, and the influences of Tx and Rx coil radius on the effective transfer distance are studied in detail. In addition, they are not proportional and the coil impedance is the most important factor. On this basis, a coil design method is proposed. Finally, an experiment device was built, and experimental results were well consistent with the theoretical analysis, showing the rationality and effectiveness of the proposed method.

Highlights

Wireless power transfer (WPT) is a contactless power transfer (CPT) technique, which uses space soft medium to convert electricity into other forms of energy, realizing the wireless transfer of electric energy after being transmitted for a distance without direct contact [1]–[3]
The main contributions of this paper are as follows: 1) We describe the simulation model that study the influence of Tx/radius of the Tx (Rx) coil radius on the effective transfer distance at 6.78MHz and present that they are not proportional
In the case of certain resonant frequency and load, as the coil radius on one or both sides of the WPT system grows, the effective transfer distance first increases to its maximum and gradually decreases; a too small or too large coil radius will affect the effect on the WPT system

Summary

Introduction

Wireless power transfer (WPT) is a contactless power transfer (CPT) technique, which uses space soft medium to convert electricity into other forms of energy, realizing the wireless transfer of electric energy after being transmitted for a distance without direct contact [1]–[3]. There exists a serious problem, i.e., the transfer power and power transfer efficiency (PTE) of the WPT system will drop sharply with the increase in transfer distance [10], [11]. To study the distance characteristics of WPT, the critical point at which the load received power decreases with the increase in the distance between coils is defined. The distance between the Tx coil and the critical point is called effective

Objectives

Results

Conclusion