毕业设计（论文）-基于小波变换及BP网络的变频器故障诊断精选.doc

摘 要 三相交流变频驱动系统以其优良的调速性能，良好的节能效果，越来越广泛的应用于工业、商业、航空等领域。由于控制算法的复杂性及半导体器件的自身特点，驱动器易发生故障。论文针对变频器的故障诊断进行研究，在建立变频器 AC-DC-AC 模型的基础上，对各种故障类型进行理论分析与仿真实验，总结各种故障并相互比较，给出基于小波变换和神经网络的故障诊断方法。 由于条件所限，无法得出故障情况下的各种故障信息，以作为故障诊断的基础，所以本文首先对变频调速系统在MATLAB软件中进行仿真，建立了变频调速系统的仿真模型。在此基础上，模拟了几种常见的变频器本身的故障，诸如开关元件的短路、开路等。并提取了故障信息一变频器的三相输出电流信号。运用傅立叶变换后，得到了故障情况下，电流的幅频特征信息，以此作为故障诊断的依据。此信息送入一个优化设计后的神经网络中，经此神经网络可判断故障发生的具体位置，从而减少故障维修时间，并为下一步处理提供依据。本文在变频器的故障诊断中首次采用神经网络进行诊断。利用了神经网络的自学习、非线性、联想等优点，从而使变频器运行更为可靠。仿真结果表明：该方法可诊断 PWM 逆变电路故障，且收敛速度快，诊断准确度高。 关键词：变频器，故障诊断，小波变换，神经网络 Abstract Induction motor drive system has been widely used in industrial, commercial and aerospace applications, etc, for its excellent speed control performance and energy saving. However, the complexity of the control strategy and the features of semiconductor results easily in various failures of the drive system. The paper mainly aimed to frequency converter for fault diagnosis，in the establishment of AC-DC-AC invertermodel based on the type of fault on the various theoretical analysis and simulation results are summarized and compared various failure presented wavelet and neutral networks-based fault diagnosis. Beeause of the limit of condition,we can not get the fault information on the condition of fault which can be used as the base of fault detection and diagnosis.At first the paper build the simulation model of varied-frequency varied-speed system，and on this base，simulate some kinds of inverter faults that can be meet usually such as short and open circuit fault of switch ete，then extract the fault information-the three-phase output current of inverter.When the fault information are transformed by wavelet-transform，we can get the amplitude and frequency information of the three-phase current on the condition of the fault which can be used as the information of the fault diagnosis.The information input a NN that has been optimized.The NN can diagnosis the place where the fault took place so we can reduce the fault maintain tim