Fault diagnosis of induction motors through the analysis of the stator current is increasingly being used in maintenance systems, because it is non-invasive and has low requirements of hardware and software. Nevertheless, its industrial application faces some practical limitations. In particular, the detection of fault harmonics that are very close to the fundamental component is challenging, as in large induction motors working at very low slip, because the leakage of the fundamental can hide the fault components until the damage is severe. Several methods have been proposed to alleviate this problem, although all of them increase noticeably the complexity of the diagnostic system. In this paper, a novel method is proposed, based on the analysis of the rectified motor current. It is shown that its spectrum contains the same fault harmonics as the spectrum of the original current signal, but with a much lower frequency, and free from the fundamental component leakage. Besides, the proposed method is very easy to implement, either by software, using the absolute value of the current samples, or by hardware, using a simple rectifier. The proposed approach is presented theoretically and validated experimentally with the detection of a broken bars fault of a large induction motor.

中文翻译：

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利用整流定子电流诊断感应电机转子不对称故障

通过定子电流分析进行的感应电动机故障诊断越来越多地用于维护系统中，因为它是非侵入性的，并且对硬件和软件的要求较低。然而，其工业应用面临一些实际限制。特别是，检测非常接近基波分量的故障谐波具有挑战性，例如在以非常低的滑差工作的大型感应电机中，因为基波的泄漏可以隐藏故障分量，直到损坏严重为止。已经提出了几种方法来缓解这个问题，尽管所有这些方法都显着增加了诊断系统的复杂性。在本文中，基于对整流电机电流的分析，提出了一种新方法。结果表明，其频谱包含与原始电流信号频谱相同的故障谐波，但频率要低得多，并且没有基波分量泄漏。此外，所提出的方法非常容易实现，无论是通过软件，使用当前样本的绝对值，还是通过硬件，使用简单的整流器。所提出的方法从理论上提出，并通过检测大型感应电机的断条故障进行实验验证。