复调制Zoom-FFT方法的LabVIEW实现与应用

Implementation and Application of Zoom-FFT Based on LabVIEW

摘要:

信号频谱中频率分量接近时,在较低的频域分辨率下难以检测,而传统FFT分析在提高频域分辨率的同时导致计算量大大增加;针对此问题,在LabVIEW平台中采用复调制Zoom-FFT方法,通过移频、滤波、重采样、FFT和频率调整实现频谱的细化;结果表明,复调制Zoom-FFT可以灵活地选择细化频带,提高频带内的频域分辨率并有较小的计算量；此外,合理的选择窗函数能够减少频谱失真;将该方法应用于异步电机故障诊断中,实现了转子断条故障分量的检测,为LabVIEW中的频率检测与故障诊断提供一种有效途径。

Abstract:

In signal spectrum, it is difficult to detect the close frequency components under a low resolution. When using the traditional FFT to improve frequency resolution will lead to a large increase in computing. To solve this problem,a complex modulation Zoom-FFT method is used on LabVIEW platform. Spectrum zooming is achieved by several steps including frequency shifting, filtering, resampling, FFT and frequency adjustment. Results show that this method can not only flexibly select the zooming frequency band and improve frequency resolution, but also has a small demand of computation. In addition, a reasonable choice of window function can reduce spectral distortion. The rotor bar broken fault is detected when using this method to the induction motor fault diagnosis. Therefore, it provides an effective way for frequency detection and fault diagnosis based on LabVIEW.