Experimental study on the rotor dynamics influence upon the modal characteristics of an induction machine

Abstract

The rotor of an electric machine is the direct transfer of torque and speed to the drivetrain through the shaft. As such, its vibrations might deteriorate the efficiency but also, irreversibly, the machine itself. It is particularly important to identify critical frequencies at which resonance may occur. In this paper, a newly identified structural mode is extracted experimentally on an induction machine and justifies the need for more investigations. This mode involves bending of the end-plates of the stator, together with bending of the rotor component which can potentially be a dangerous mode shape. The results are gathered by carrying various experiments in which experimental modal analyses are carried out for characterization of the test specimens. The influence of the rotor dynamics on the behavior of the complete machine is collected by testing two different rotors, alone, and then assembled with the exact same stator.