改进的VMD方法及其在转子故障诊断中的应用

Application of Improved VMD Method in Fault Diagnosis of Rotor Systems

针对转子系统油膜失稳的诊断问题以及变分模态分解(VMD)的端点效应问题,提出一种利用互信息准则进行波形匹配和端点延拓的改进VMD方法,并通过分析各分量的Hilbert谱诊断油膜失稳状态.结果表明:该方法具有良好的多分量信号分解能力和端点效应抑制效果,能有效诊断出油膜涡动的发生时刻以及发展变化特点;当单盘转子发生1阶油膜振荡时,频谱中转频和振荡频率的幅值突出,同时会出现与两者相关的组合频率成分,对准确、可靠地诊断油膜失稳具有重要意义.

To diagnose the oil film instability of rotor systems and to solve the problem of end effect occurring in variational mode decomposition （VMD）, an improved VMD method was proposed based on mutual information criterion to match the waveform and to extend the endpoints, so as to judge the instability status of the oil film by analyzing the Hilbert time-frequency spectrum of each component. Results show that the proposed method has strong decomposition capability to multi-component signals and has good inhibiting ability on the end effect, which is able to diagnose the occurrence moment and subsequent development of oil whirl. When the first-order oil whip occurs in a single disc rotor, the rotation frequency and whip frequency would become prominent in the spectrum, with simultaneous occurrence of their combination frequency components. Above research results may serve as a reference for accurate diagnosis of oil film instability.