Assessment of windowing effect on the frequency resolution of the stator current PSD for induction motor broken rotor bars diagnosis

Recent advances in power electronics and control systems have contributed to the growing use of induction machines in electric drive systems. The use of induction machines is mainly related to their robustness, their power to weight ratio and the cost of manufacture. However, various faults may appear in such machines. The power spectral density, based on the calculation of the Fourier transform is used as a method of analysis for many years for its simplicity and its low computation time. However, it is limited in frequency resolution and thus inefficient in fault detection in the case of a low motor slip (harmonic near the fundamental), in the case of highly noisy signals (false alarms) and for incipient faults detection (harmonics of low amplitude). This limitation is directly related to the use of truncation windows which induce negative effects. This results in the appearance of side lobes on both sides of the main lobe and reduces the spectral resolution. This aspect has several constraints in the analysis of stator current for the induction motor faults diagnosis. Thus, we present in this paper, the impact of the choice of truncation windows on the resolution of the power spectrum density of the stator current. Simulation results will then highlight the properties of each window.