负载波动下感应电动机转子断条故障诊断

针对波动负载下感应电动机转子断条故障特征提取与状态识别问题,研究一种基于瞬时功率与离散小波的波动负载下感应电动机转子断条故障提取方法,并给出了明确有效的检测判据。该方法计算电动机瞬时功率,进行离散小波分解并提取特征频段能量,并通过比较瞬时无功功率中特征频段的小波能量幅值Eq与瞬时有功功率中相应频段的能量幅值Ep的大小形成诊断判断。创建了以随机森林为基分类器的集成分类器,提高负载波动下感应电动机转子断条故障识别的精确性。通过实验验证了该方法及其新判据的有效性。     

基于扩充Prony算法的感应电动机转子断条故障诊断

检测感应电机转子断条故障及故障程度的关键在于查找定子电流谱中频率为(1±2s)f的间谐波含有率。传统的谱分析由于加窗和截断带来的频谱泄漏,使特征谱难以辨识,采用现代谱估计中的扩充Prony算法,基于定子电流信号的AR参数估计,计算信号的谱线构成,依据故障电机稳态运行时的定子电流特征,选取合适的阶数,能够精确地检测到(1±2s)f故障特征分量的幅值和频率,回避了频谱泄漏问题,为感应电动机转子断条故障的MCSA检测法提供了一条新的途径。通过实验室实测算例验证了该方法的有效性,在电机空载和轻载运行时也能够准确地检测出故障特征信号,诊断出故障程度。     

基于电磁转矩小波变换的感应电机转子断条故障诊断

该文提出了一种基于感应电机启动电磁转矩信号的转子断条故障诊断新方法。利用复值小波变换中的小波脊线提取出启动电磁转矩中故障特征在电机启动过程中的频率变化规律，检测出转子断条故障。同时，小波系数的模反映了信号在对应尺度上的能量大小，所以对应故障特征脊线上的小波系数模反映了该故障特征转矩的幅值变化规律。基于此，定义了脊线一小波能量谱的概念。将故障特征转矩对应的脊线一小波能量谱作为故障严重程度因子，即可根据其与转子连续断条根数的关系给出感应电机转子故障严重程度的表示方法。实验结果证明该方法是可行的。     

基于感应电机启动电磁转矩Hilbert-Huang变换的转子断条故障诊断

该文提出了一种感应电机转子故障诊断新方法。当感应电机转子出现断条故障时,转子绕组的不对称将会使电磁转矩谱中引入2sfs(s为转差率,fs为电网频率)谐波分量。利用砌bert-Huang变换中经验模态分解(EMD)方法对启动电磁转矩信号进行了分解,得到若干本征模态函数(IMF)。通过计算包含故障信息的IMF分量的瞬时频率,可以检测出转子断条故障。同时,根据包含故障信息的IMF的幅值可以进一步判断出转子断条根数。实验结果证明该方法是可行的。     

采用整流技术的变频供电感应电机转子断条故障诊断方法

电机定子电流信号易受变频器电力电子开关器件和电磁干扰的影响,现有解调技术又存在计算量大的问题,为此,该文提出一种变频器供电侧电流与整流技术相结合的感应电机转子断条故障诊断方法。所提方法依据开关函数和调制理论,首先建立了变频器供电侧电流解析表达式。其次利用整流技术对变频器供电侧电流进行处理,将特征频率从传统的边带频率转化为转子断条故障特征频率,有效地抑制了电源基频频谱泄漏的影响,从而实现电机在轻载或空载运行工况下的转子断条故障诊断。最后采集变频供电感应电机不同负载运行工况下供电侧电流数据进行验证。实验数据分析表明,所提方法能够提取从空载到重载不同运行工况下的转子断条故障特征分量,有较高的稳定性,而且所需计算量少,容易实现。     

起动过程诊断感应电动机转子断条故障

针对稳态定子电流频谱难以突出故障特征分量的弱点,提出了基于起动过程的感应电动机转子断条检测方法。故障特征频率的定子电流分量对气隙磁场有调制作用,导致定子电流、电磁转矩和转子转速的周期性脉动,这些故障特征在起动过程中表现明显。通过监测感应电动机的整个起动过程,可实现对转子断条的故障检测。实验结果表明该方法行之有效。     

笼型感应电动机转子断条和开裂的故障诊断和在线监测

分析了笼型感应电动机转子故障时导条断条和端环断裂的物理模型 ,给出了电动机的定转子绕组的参数计算表达式 ,建立了数学模型 ,从而导出转子故障时的电流和频谱分析。本文分析了电动机在故障时 ,在dqn任意速坐标系中 ,电动机定子电流的轨迹 ,为电动机的故障诊断和在线监测提出了一种新的方法 ,较以往的电流监测方法更有利于克服边频带的影响。     

基于RMO的感应电动机转子断条故障检测

为了克服传统基于快速傅里叶变换(FFT)的定子电流特性分析方法(MCSA)的频谱泄露问题,提出了一种基于径向移动(RMO)算法的感应电动机转子断条故障检测方法。首先采用RMO估计定子电流中的基波分量参数,进而构造基波表达式并将其从定子电流中滤除,从而得到残余电流信号,同时凸显故障特征;然后利用RMO估计残余电流信号中幅值较大边频分量的参数并构造相应表达式,进而将其从残余电流信号中滤除,得到新的残余电流信号。同理可将新的残余电流信号中的另一个边频分量参数进行RMO估计。至此,便可以获得感应电动机转子断条故障时基波以及边频分量的参数大小。最后,通过实验验证了该方法的可行性。     

变频器供电情况下感应电动机转子断条的诊断

变频调速技术的应用已遍及各个控制领域,同时由变频器高速通鄄断开关作用所带来的电磁干扰问题也引起了人们的关注。文章对变频器供电情况下感应电动机定子电流信号中的各谐波分量及电磁干扰问题进行了分析研究,提出了减少测量电路干扰的有效方法。在此基础上,用时变频谱分析法实现了感应电动机转子断条的诊断。     

基于Hilbert模量频谱分析的异步电机转子断条故障研究

转子绕组断条是异步电机最常见故障之一.在分析当前主要诊断方法的基础上,提出Hilbert 模量频谱分析方法对异步电机转子断条故障进行研究.将Hilbert模量定义为原始信号与其共轭信号的平方和,利用Hilbert模量将原相电流中的基波分量转变为直流分量,原频谱分析的转绕组断条的故障特征分量转变为频率为二倍转差频率的电流分量,决了相电流频谱分析方法中断条故障特征成分容易被基波湮没而难以突出故障特征的问题.文中研究了Hilbert模量频谱分析方法的原理和实现方法,并对偏心故障电机和转子断条电机分别进行仿真和实验研究.仿真分析和实验结果均表明,该方法对异步电机转子断条故障诊断具有较高的诊断精度和很好的频率分辨率,能克服传统的电流频谱法主频泄漏的影响,且工程实现方便.     

希尔伯特变换在牵引电机转子断条故障诊断中的应用研究

基于希尔伯特变换分析方法,以动车组电机定子电流信号为研究对象,对定子电流信号应用希尔伯特变换后,消去定子电流中包含的直流分量,解决了转子断条故障特征分量容易被基波淹没、难以检测等问题,使故障特征分量的提取更加准确。通过仿真实验证明了希尔伯特变换法在动车组牵引电机转子断条故障诊断中应用的正确性和有效性。     

基于谐波小波的变频机转子断条故障诊断

变频机转子发生断条故障时,定子电流中将产生相应特征频率的电流分量.对这种特征信号的提取与监控,能够实现转子短条故障的检测.研究利用谐波小波的分频特性实现转子断条故障特征信号的提取方法.仿真结果和实际应用表明,这种方法能够准确地提取转子导条断裂故障的特征信号,是变频机转子导条断裂故障诊断的一种可靠的方法.     

Diagnosis of rotor asymmetries in induction motors based on the transient extraction of fault components using filtering techniques

The aim of this paper is to present and validate a methodology for diagnosing rotor asymmetries in cage motors, based on the analysis of the stator startup current. The method consists of the extraction of a harmonic component introduced by this fault – the left sideband component – from the stator startup current. Two alternative techniques developed by different research groups are proposed for the transient extraction of this component; the digital low-pass filtering (DLPF) and the discrete wavelet transform (DWT). Both approaches are applied to three different industrial motors ranging from 1.1 to 450 kW. A detailed explanation of the physical basis of the method and comments related to the application scope of the approach are also given. The results show the robustness of both approaches for the reliable diagnosis of the fault and suggest a clear potentiality for extending the methodology to the detection of other types of faults introducing components dependant on the slip.     

Stator current fault diagnosis of induction motor bearings based on the fast Fourier transform

Monitoring of the technical state of induction motor bearings is one of the important indicators of reliable and efficient operation of industrial electrical drives. This article considers the problems of fault diagnosis of induction motor bearings with a squirrel-cage rotor by stator consumption current. Test results on an experimental test bench with an electromagnetic powder brake are presented and analyzed. Experiments were carried out during tests of the induction motor at the rated mode with an operable bearing and alternately with two faulty bearings with defects at the inner and outer parts of cages. The characteristic harmonic components of stator currents appearing during operation of the induction motor with faulty bearings are presented. It is revealed that an anticipatory diagnosis of induction motors by stator current makes it possible to reveal the air-gap eccentricity due to the operation of an electric motor with a damaged bearing. Control of the technical state of bearings is important both during at the stage of manufacturing machines, in particularly for powerful and crucial mechanisms, and during their use. The basic features of monitoring the bearings are revealed, and recommendations for diagnosis by stator currents are presented.     

Rotor bar fault diagnosis in three phase induction motors by monitoring fluctuations of motor current zero crossing instants

This study describes broken bar detection in induction motors without using additional sensor. It is based on observation of the fluctuations of stator current zero crossing times (ZCT). Instead of sampling motor current with a high resolution A/D converter, zero crossing instants are recorded as waveforms cross zero. Fluctuations in the intervals between successive zero crossings of the three phase current waveforms are analysed using Fast Fourier Transforms (FFT). Diagnostic information is found in the spectrum of the ZCT signal through the presence of specific fault related frequencies. A rotor bar fault is manifested as an increase in the amplitude of the 2sf and other spectral components. This paper analyses the effect of an electrically unbalanced rotor on the ZCT spectrum of stator current, and discusses the various frequency components associated with rotor bar faults seen in the ZCT spectrum. It is important to eliminate the dependence of the index on the parameters of the induction motor. Particularly, the effect of motor inertia, supply harmonics, and variable load are discussed to increase the reliability of the rotor fault index, and simulation results are presented. It is found that the 2sf frequency component is independent of inertia, load, and harmonics, and thus it is suitable as an index for broken rotor bar.     

基于Hilbert变换的感应电机转子断条故障研究

在分析当前主要诊断方法的基础上,采用Hilbrt变换频谱分析方法对不同负载情况下的感应电机转子断条故障进行研究。通过与FFT频谱分析对比,该方法对感应电机转子断条故障诊断具有较高的诊断精度和很好的频率分辩率,能克服FFT电流频谱法主频泄漏的影响,更好地实现感应电机的转子断条故障诊断。     

大型电动机故障诊断与保护理论综述

分析了大型电动机故障诊断与保护理论的研究现状和发展趋势,主要讨论了以过流保护为基础的电动机常规保护、基于对称分量法的新型综合保护、基于先进信号处理方法及多回路理论的大型电动机在线监测和故障诊断。认为内部故障定量分析方法的理论突破是实现大型电动机故障早期诊断的关键,这一理论和先进信号处理方法及微机技术的结合可望使大型电动机的故障诊断与保护取得新的突破。     

Analysis of rotor failures in squirrel-cage induction motors

The authors describe a procedure for analyzing rotor failures in squirrel-cage induction motors. They attempt to identify the various kinds of failure classes and patterns and relate them back to the probable cause of failure. They discuss five key areas that must be considered and related to one another in order to accurately diagnose the cause of rotor failure: failure class, failure pattern, appearance, application, and maintenance history. Finally, a summary of typical failures and tell-tale rotor appearances is presented