Foreign object detection considering misalignment effect for wireless EV charging system

Songyan Niu; Cheng Zhang; Yujun Shi; Shuangxia Niu; Linni Jian

doi:10.1016/j.isatra.2022.04.016

Foreign object detection considering misalignment effect for wireless EV charging system

ISA Trans. 2022 Nov:130:655-666. doi: 10.1016/j.isatra.2022.04.016. Epub 2022 Apr 18.

Authors

Songyan Niu¹, Cheng Zhang², Yujun Shi², Shuangxia Niu³, Linni Jian⁴

Affiliations

¹ Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China; Department of Electrical Engineering, The Hong Kong Polytechnic University, 999077, Hong Kong, China.
² Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
³ Department of Electrical Engineering, The Hong Kong Polytechnic University, 999077, Hong Kong, China.
⁴ Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China. Electronic address: jianln@sustech.edu.cn.

PMID: 35525608
DOI: 10.1016/j.isatra.2022.04.016

Abstract

Foreign object detection (FOD) is crucial to preventing wireless electric vehicle charging (WEVC) systems from thermal risk caused by intruded metals in the charging area. In practice, the spatial misalignment between EV and ground-assembled power transmitter is evitable. Unfortunately, according to our quantitative analysis based on conventional voltage-difference-based method, a misalignment of merely tens of mm has been enough to severely deteriorate the FOD accuracy. To combat this misalignment effect, a FOD strategy based on passive sensing coils utilizing voltage vector decomposition (VVD) is proposed in this paper. The proposed strategy can be invariant to misalignment in an automatic manner, during the whole charging process, and regardless of the resonance state of charging circuit. To facilitate VVD implementation, a method called inductance-misalignment mapping (IMM) is devised to obtain the spatial misalignment of EV in real time, and it can be executed by reusing the sensing coils without introducing extra cost. The effectiveness of optimized sensing coils with the proposed FOD method is validated successfully using a commercialized 3-kW prototype working from light load to rated load.

Keywords: Electric vehicle (EV); Foreign object detection (FOD); Inductive power transfer (IPT); Misalignment; Sensing coil.