Identification of intermittent electrical and mechanical faults in permanent-magnet AC drives based on time-frequency analysis

The detection of noncatastrophic faults in conjunction with other factors can be used to determine the remaining life of an electric drive. As the frequency and severity of these faults increase, the working life of the drive decreases, leading to eventual failure. In this paper, methods are presented to identify developing electrical and mechanical faults based on both the short-time Fourier transform and wavelet analysis of the field-oriented currents in permanent-magnet ac drives. The different fault types are classified by developing a linear discriminant classifier based on the transform coefficients. Index Terms--Intermittent fault detection, permanent-magnet ac (PMAC) drives, short-time Fourier transform (STFT), undecimated discrete wavelet transform (UDWT).