As inductive debris detection has several unique advantages such as simple structure, usability for metallic flow channel and non-sensitivity to the quality of lubricant, it has been more and more applied in the mechanical fault diagnosis and condition-based maintenance. However, the inductive principle is easily interfered by electromagnetic variations and mechanical vibrations in the actual working condition, which limits the detection resolution and the early mechanical wear prediction. Although some signal processing methods have been proposed to improve the signal-to-noise ratio (SNR), the fundamental denoising idea for sensor designs is still absent. This paper proposes using common-mode rejection to eliminate interferences for inductive debris detections. The mathematic model is built to discuss the rejection effect, and the magnetic distribution is simulated to analyze the sensor structure. Finally, a debris sensor is designed to validate the performance through conducting actual debris detections and external interference experiments. The results indicate that the sensor can effectively eliminate the multiple interferences such as alternating power, oil pulsation, electromagnetic variation and mechanical vibration. Especially, the SNR has been improved about 7.5 times in the actual debris detection, which demonstrates a good potential for applications.

中文翻译：

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基于共模抑制消除感应碎片检测的干扰


由于感应式碎片检测具有结构简单、适用于金属流道、对润滑油质量不敏感等独特优点，在机械故障诊断和状态检修中得到越来越多的应用。然而，感应原理在实际工况下容易受到电磁变化和机械振动的干扰，限制了检测分辨率和早期机械磨损预测。尽管已经提出了一些信号处理方法来提高信噪比（SNR），但传感器设计的基本降噪思想仍然缺乏。本文提出使用共模抑制来消除感应碎片检测的干扰。建立数学模型来讨论抑制效应，并模拟磁场分布来分析传感器结构。最后，设计了碎片传感器，通过进行实际碎片检测和外部干扰实验来验证其性能。结果表明，该传感器能有效消除交流电源、油脉动、电磁变化、机械振动等多重干扰。特别是在实际碎片检测中，信噪比提高了约7.5倍，具有良好的应用潜力。