Non-stationary condition torsional vibration monitoring using induction machine electromagnetic torque estimation

Mechanical anomalies like load troubles, great torque dynamic variations and torsional oscillations, result in the fatigue of the shaft driving electrical machine and other mechanical parts as bearings and gearboxes of complex electromechanical systems. Particularly in non-stationary condition, torsional vibration can reach important levels at resonant frequencies by producing weaknesses in the mechanical part and lifetime consumption during an event. In this way, this paper proposes electromagnetic torque estimation using noninvasive measuring as a means for mechanical torsional stresses monitoring in an induction machine driving system at non-stationary operating condition. A test-bed based on a 5.5 kW squirrel-cage induction machine connected to one-stage gearbox has been used to validate the proposed method.