Techniques to estimate the instantaneous frequency with an aim of diagnosis induction machines faults

In this work we present a new techniques to detect a mechanical faults in asynchronous machines by exploiting the instantaneous frequencies estimated starting from an accelerometer sensor, optical encoder and stator current. Bearing damages cause a torque oscillations as well as a disturbance in the velocity signal which can be detected by a mechanical measurements. These fluctuations will be reflected on the stator currents and cause a phase modulation. Where, the idea to exploit the instantaneous frequency in order to find informations related to the defect. An experimental data were used to verify the validity of the different techniques. Data were collected through an accelerometer sensor to measure the mechanical vibrations, an optical encoder fixed on rotor shaft and by electrical measurements. The results, in presence of natural raceway bearing fault, illustrate the very good performance of the proposed methods.