This study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device’s capability to enable recognition of rotor PMs’ magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

中文翻译：

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使用气隙磁传感器的电机永磁体健康监测和诊断

本研究提出了一种磁传感器设计和应用，用于通过现场观察气隙磁通密度来监测永磁 (PM) 电机中转子磁体的健康状况。所报告的设备采用光纤布拉格光栅 (FBG) 应变传感融合与磁致伸缩材料的概念来提供机器定子槽楔集成传感器，该传感器允许直接安装和改造，无需对机器的核心元件进行侵入性操作。本文详细介绍了所提出的磁传感方案的传感理论、设计、原型设计、校准和安装。该传感器安装在逆变器驱动的表面贴装 PM 同步电机 (SPMSM) 中，其在转子 PM 磁化条件的原位观察方面的性能在一系列健康和去磁 PM 条件测试中得到验证。获得的实验数据证明了所报告的设备能够识别转子 PM 的磁化水平，从而对其进行健康监测。最后，提出并通过实验验证了故障指数，该指数允许将原位磁传感器测量应用于 PM 退磁故障严重性的相对量化。