基于谐波注入电机轴承故障特征研究

发布时间：2018-03-21 08:27

本文选题：感应电机　切入点：轴承　出处：《大连海事大学》2017年硕士论文　论文类型：学位论文

【摘要】：三相感应电机因其具有结构简单、运行可靠等优点,在工业生产的各个领域发挥着重要作用。轴承故障作为发生概率最高的一种故障形式,很容易导致电机出现不可修复的损坏。因此,对电机轴承故障进行早期故障诊断的研究具有重要的意义。本文针对Blodt提出的轴承故障模型在电机定子电流诊断中的不足,从动力学角度研究轴承故障时的振动表现形式。基于轴承故障引起的转子重心偏移从而导致的恢复力变化情况,在充分考虑轴承运动过程中负荷分布和受力变化的前提下,搭建了轴承外圈单点故障下的动力学模型。通过模型仿真和解析计算,分析了轴承故障下的振动特性,推导了轴承故障的振动形式、振动频率、衰减系数的关系式,最终求得了轴承单点故障时摩擦力矩表达式,给出了轴承故障转矩变化的新模型。在新模型的基础上,重新推导了轴承故障时电机定子电流特征频率的表达式,得到定子电流中各个特征边频的幅值随着故障宽度和电机转速变化的规律。通过仿真研究,对不同故障宽度下和不同转速下的电流频谱进行比对分析,仿真结果初步验证了上述结论的正确性。利用轴承动态摩擦力矩测试台,实际测试了轴承故障时的摩擦力矩变化情况,验证了动力学模型的准确性。针对感应电机实际检测中,轴承故障的弱特征信号易被淹没在电源基频附近的高噪声背景中,不利于轴承故障检测的情况,设计了谐波注入感应电机轴承故障实验平台,把轴承故障特征频率与注入的较高频率的谐波相调制,提高故障特征的可识别性。实验结果验证了上述的结论,在结论对正确判断轴承故障以及故障的严重程度提供了有效的理论依据。
[Abstract]:Because of its simple structure and reliable operation, three-phase induction motor plays an important role in various fields of industrial production. It is easy to cause irreparable damage to the motor. Therefore, it is of great significance to study the early fault diagnosis of the motor bearing fault. This paper aims at the deficiency of the bearing fault model proposed by Blodt in the stator current diagnosis of the motor. Based on the change of the restoring force caused by the rotor center of gravity deviation caused by the bearing fault, the load distribution and the force change in the course of bearing motion are fully considered. The dynamic model of bearing outer ring under single point fault is built. The vibration characteristics of bearing fault are analyzed by model simulation and analytical calculation, and the relationship between vibration form, vibration frequency and attenuation coefficient of bearing fault is deduced. Finally, the expression of friction torque of bearing at single point fault is obtained, and a new model of bearing fault torque change is given. On the basis of the new model, the characteristic frequency expression of stator current of motor under bearing fault is derived again. The amplitude of each characteristic side frequency in stator current varies with the fault width and motor speed. Through simulation, the current spectrum under different fault width and different rotating speed is compared and analyzed. The simulation results preliminarily verify the correctness of the above conclusions. By using the bearing dynamic friction torque test bench, the variation of the friction torque during the bearing failure is tested, and the accuracy of the dynamic model is verified. The weak characteristic signal of bearing fault is easily submerged in the high noise background near the basic frequency of power supply, which is not conducive to bearing fault detection. A bearing fault test platform for harmonic injection induction motor is designed. The characteristic frequency of bearing fault is modulated with the harmonic wave of higher frequency injection to improve the identifiability of the fault feature. The experimental results verify the above conclusion. The conclusion provides an effective theoretical basis for correctly judging the bearing fault and the severity of the fault.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM346

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