Stator current harmonics and their causal vibrations: a preliminary investigation of sensorless vibration monitoring applications

This paper presents an initial study into the relationship between vibration and current harmonics of electric motors, including the effect of externally induced vibrations. This relationship was investigated experimentally on both new motors, on a vibration stand, and a motor with bearing wear. Both theory and experimental results show that a change in the RMS value of the stator current is directly related to the change in vibration magnitude, for a known vibration frequency. The paper shows this result both for a new motor with an externally induced vibration and for a motor with vibration caused by progressive bearing wear.