Computation of the Mutual Inductance between Air-Cored Coils of Wireless Power Transformer

A O Anele,Y Hamam,J Linares,Y Alayli,K Djouani,L Chassagne

doi:10.1088/1742-6596/633/1/012011

Abstract

Wireless power transfer system is a modern technology which allows the transfer of electric power between the air-cored coils of its transformer via high frequency magnetic fields. However, due to its coil separation distance and misalignment, maximum power transfer is not guaranteed. Based on a more efficient and general model available in the literature, rederived mathematical models for evaluating the mutual inductance between circular coils with and without lateral and angular misalignment are presented. Rather than presenting results numerically, the computed results are graphically implemented using MATLAB codes. The results are compared with the published ones and clarification regarding the errors made are presented. In conclusion, this study shows that power transfer efficiency of the system can be improved if a higher frequency alternating current is supplied to the primary coil, the reactive parts of the coils are compensated with capacitors and ferrite cores are added to the coils.

Highlights

Wireless power transfer (WPT) systems allow the transfer of electric power between the aircored coils of its transformer via high frequency magnetic fields to a consuming device [1,2,3]
This is so because the example studied in [7, 10] considered the case with only lateral misalignment
This study shows that as the coil separation distance and misalignment increase, the mutual inductance between the coils decreases

Summary

Introduction

Wireless power transfer (WPT) systems allow the transfer of electric power between the aircored coils of its transformer via high frequency magnetic fields to a consuming device (e.g. electric vehicle) [1,2,3]. Several mutual inductance models based on the application of Maxwell’s formula, Neumann’s formula, Biot-Savart law and magnetic vector potential approach have been presented in [3,4,5,6,7]. These models are developed based on analytical or semi-analytical forms expressed over elliptical integrals of the first, second and third kinds, Heuman’s Lambda function, Bessel functions and Legendre functions [6,7,8,9,10]. A more advanced and relevant model for evaluating the mutual inductance between circular coils with misalignment have been formulated in [6, 7]

Objectives

Discussion

Conclusion