【作者】 马婧；

【导师】 李强；

【作者基本信息】 西安理工大学 ， 检测技术与自动化装置， 2008， 硕士

【摘要】 目前,应用在同步发电机上的无刷励磁技术,取消了原有励磁系统中滑动接触部分(滑环、碳刷),提高了运行的可靠性,因此近几年同步无刷励磁发电机在工业中的应用越来越广泛。同步无刷励磁发电机主要是依靠交流励磁机和旋转整流器来实现无刷励磁的,由于旋转整流器安装在电机转轴上,随电机转子一起旋转,其核心器件整流二极管会承受很大的离心力,故障率较高。旋转整流器的失效会导致同步电机不能正常运行,严重时还会对交流励磁机造成一定的损失,因此对旋转整流器进行实时监测与故障诊断是非常重要的。由于无刷励磁系统取消了滑环和碳刷,旋转整流器的电压和电流不可能直接测量,使其监测和保护十分困难,但又可知当旋转整流器发生故障时,交流励磁机电枢绕组产生的磁场就会发生异常,感应出交流电势也会随着不同的运行状态产生不同的谐波分量。本文通过检测线圈法,对感应电势进行谐波分析,采用综合故障诊断法,对同步无刷励磁发电机旋转整流器故障进行在线故障诊断。谐波分析使用FFT得到励磁绕组中感应电势的各次谐波幅值,而FFT主要存在有频谱混叠、频率分辨能力、栅栏效应及频谱泄漏等问题。本文使用模拟滤波器;选择合适的采样频率和采样点数;采用加窗法和幅值比值校正法对FFT进行减小误差处理,经过处理效果明显提高。目前已有的故障诊断法主要有阈值法,神经网络法和模糊模式识别法等,本文对比了他们各自的优缺点,提出了综合故障诊断法,即先用阈值法判断故障是否发生,如有故障发生则使用神经网络法与模糊模式识别法相结合的方法来具体判断故障类型,如没有故障发生则继续监测。本文使用TMS320F2812作为旋转整流器故障诊断系统的中心处理器,分析感应电势中的各次谐波幅值,采用综合故障诊断法进行故障诊断,使用液晶屏将显示信息,并通过触摸屏完成参数设置和系统操作。更多还原

【Abstract】 Brushless exciter has been used in generator for many years; it has canceled slip rings and carbon brushes, and improved its operational stability. So in recent years, synchronous brushless excitation generator has been increasingly used in the industrial application.Synchronous brushless excitation generators mainly rely on the exchange exciter and rotating rectifiers to achieve brushless excitation. Because rotating rectifiers work with the motor shaft, and install on the motor rotor rotation. The core of rotating rectifiers is diode device, it tremendous centrifugal force, so its failure rate is high. The failure of rotating rectifier can lead to the synchronous motor can not operate normally. Therefore the real-time monitoring and diagnosis of rotating rectifier’s failure is very important.Because brushless excitation system has canceled slip rings ands carbon brushes, it’s voltage and current can not be measured directly, so it’s difficult to be monitored and protected. But it is been known that when failure has happen, the exchange of armature winding excitation generated magnetic field will be abnormal, the AC induction potential will be different with the operation of the state which have different harmonics. In this paper, using detection coil method, harmonic analysis, use comprehensive diagnostics, achieve the monitoring and fault diagnosis of the brushless synchronous generator excitation rotating rectifier.FFT analysis by the use of harmonic excitation winding induction potential of the various harmonic amplitude, and the major existence of FFT spectrum aliasing, frequency resolution capability, and the effect of the fence spectrum leakage problems. In this paper, using analogue filter; choose suitable sampling frequency and sampling points; using window law and adjusting method to reduce the error of FFT, the results have been markedly improved.At present, the methods of fault diagnosis mainly are threshold method, neural network and fuzzy pattern recognition, etc. The paper compares the advantages and disadvantages of them and proposes an integrated fault diagnosis, so use threshold method determine whether the fault, if has malfunction in the use of neural networks and fuzzy combination of pattern recognition methods to determine the specific types of faults, if has no faults then continue to monitor.In this paper, use TMS320F2812 as central processor of fault diagnosis system; induction of electric potential in the various harmonic amplitude, integrate fault diagnosis method fault diagnosis, use liquid crystal to display screen information, and complete control system through the touch screen.更多还原