运用BF-HHT的转子径向碰摩故障特征提取方法

针对现有希尔伯特-黄变换(HHT)方法在进行特征提取时,估算部分多频固有模式函数(IMF)瞬时频率不准确的问题,提出了一种基于带通滤波的希尔伯特-黄变换算法(BF-HHT)。该算法首先确定信号主要能量所在频率;然后以这组主要能量所在频率为中心频率设计一组带通滤波器,对原信号进行滤波;最后用HHT方法提取信号的时频特征。转子试验台和实际机组的径向碰摩故障信号的试验与分析结果表明,BF-HHT算法不仅能准确提取到转子径向碰摩故障信号中出现的频率成分,而且能对故障特征频率出现或消失的时刻精确定位,其特征提取效果明显优于HHT方法。

Fault Feature Extraction Method for Rotor System Under Radial Impact Based on BF-HHT

As radial impact signals are often composed of rich frequency components continuously distributed in a wide region,accurately extracting the characteristic frequencies of vibration signals of a rotor system under radial impact is of great significance for fault diagnosis.The customary Hilbert-Huang transform(HHT) cannot be directly used to decompose such signals into several mono-frequency intrinsic mode functions(IMFs).Because of the existence of multi-frequency IMFs,the estimations of instantaneous frequencies for these signals are usually inaccurate.A new feature extraction method is developed in this study,i.e.,the bandpass filtering HHT(BF-HHT),which can accurately extract the characteristic frequencies of radial impact signals.Firstly,frequencies with main power are collected through calculating power spectrum densities of the signals′.Secondly,a set of bandpass filters with centering frequencies selected from the first step are designed to filter the original signals.Finally,the time-frequency characteristics are extracted from the filtered signals by HHT.Both the customary HHT and the BF-HHT are used to analyze the signals collected from rotor test bench and industrial sites.Comparisons between the results from both the methods show that,the BF-HHT can be used to extract the characteristic frequencies of radial impact signals,meanwhile,it can explore the instantaneous characteristic frequencies.