Signalverarbeitungsverfahren und virtuelle Instrumente zur Messung von elektrischen Signalen und zur Fehlerdiagnose an Maschinen

It will be shown that the chirp-z-transform and zero-padding, combined with a appropriate
window, are suitable for the estimation of the parameters of the voltage and current signals
with moderate computational complexity. Through the analysis of the spectral interference in
the discrete time Fourier transform the conditions for the simultaneous use of the windows
and the chirp-z-transform or zero-padding will be presented. The statistical errors of the
estimations will be discussed.
The time domain averaging will be here investigated to process harmonic components in the
output signals of frequency converters. For the detection and measurement of interharmonics
a digital difference-filter will be proposed. Simulations and field test results are provided to
illustrate the utility of the time domain averaging and the difference-filter.
Based on the analysis of the faults of gears and rolling bearings the virtual instruments for the
fault diagnosis and vibration analysis in epicyclic gearboxes are developed. The practical
applications show that the spectrum of the demodulated high-frequency vibration – envelope
spectrum – contains a pattern of spectral lines at frequencies which can be related to the faults
on the inner or outer race of rolling bearings.