Current-based sensorless vibration monitoring of small synchronous machines

This paper presents an initial study into the relationship between mechanical vibrations and their effect on the airgap and the resultant stator and field current harmonics in low and medium voltage synchronous machines. Experimental results show that the modulation of the airgap by mechanical vibrations can be detected in the stator and field current spectra and are monotonically related for a given vibration/current harmonic set. This paper presents experimental results for a 4 kW, 240 V, 4 pole wound-field synchronous motor tested at two different load conditions for five levels of rotor imbalance.