Purpose

This study aims to solve the problem of the existing metal foreign object (MFO) detecting systems, which are not sensitive to the small size MFO in wireless charging region of electric vehicle (EV) because of the extremely complex signal noise in the process of wireless charging of EV.

Design/methodology/approach

A method for MFO detection based on the principle that MFOs can cause mistuned resonance of detection coil resonant circuit is proposed. The general scheme of detecting system is proposed. The design method for detection coils which is effective to small MFOs detection in large-area region of wireless charging of EV is presented. The design of time-sharing driving circuit and amplifying circuit of high frequency exciting signal for detection coils is introduced. The design scheme of signal processing circuit (including filter and rectifier) of detection coil terminal voltage is also proposed.

Findings

The influence of exciting frequency of detection coils on detecting sensitivity and the anti-noise feature of system are analyzed according to the experiment results.

Originality/value

The experiment of MFO detection indicates that the proposed method can effectively detect the coin-sized small MFO in the process of wireless charging of EV.

中文翻译：

---

电动汽车无线充电系统中金属异物的检测方法

目的

这项研究旨在解决现有的金属异物（MFO）检测系统的问题，该系统由于无线过程中信号噪声极其复杂而对电动汽车（EV）的无线充电区域中的小尺寸MFO不敏感电动汽车充电。

设计/方法/方法

提出了一种基于MFO会引起检测线圈谐振电路误谐振的原理的MFO检测方法。提出了检测系统的总体方案。提出了一种在大面积电动汽车无线充电区域有效检测小型MFO的检测线圈的设计方法。介绍了用于检测线圈的高频激励信号分时驱动电路和放大电路的设计。提出了检测线圈端电压的信号处理电路（包括滤波器和整流器）的设计方案。

发现

根据实验结果，分析了检测线圈的励磁频率对检测灵敏度和系统抗噪特性的影响。

创意/价值

MFO检测实验表明，该方法可以在电动汽车无线充电过程中有效检测硬币大小的小MFO。