Diagnosis of Mechanical Unbalance Fault in Permanent Magnet Synchronous Machine Drives

In recent years, motor current signature analysis has been used for fault diagnosis of permanent magnet synchronous machines. However, the fault feature is not obvious and is easily hidden in the main component, since the amplitudes of fault harmonic components are quiet small compared with the fundamental component. A new method to diagnose the mechanical unbalance fault effectively in permanent magnet synchronous machine drives is proposed in this article, where Park's vector is used to eliminate the fundamental component from the fast Fourier transform (FFT) results of motor current signature analysis; the fault feature is then analyzed by discrete wavelet transform. The effectiveness of the proposed method is validated by simulation and experimental results. It is shown that the proposed diagnosis method may work well under different control strategies.