State space model for vibration control with arbitrary controller structures for soft mounted induction motors with sleeve bearings fixed on active motor foot mounts

摘要

In the paper, a state space model for vibration control with arbitrary controller structures for soft mounted induction motors with sleeve bearings fixed on active motor foot mounts is shown. Besides the mathematical description of the forced vibrations caused by dynamic rotor eccentricity, a procedure is presented to derive the threshold of vibration stability. The challenge of the paper is the use of arbitrary controller structures with different feedback strategies - feedback of the motor feet displacements, velocities or accelerations - in combination with a special vibration system. This specialty is, that the stiffness and damping matrices depend on the rotor angular frequency Ω, which corresponds to the excitation angular frequency, when analyzing the forced vibration, and depend additionally on the natural angular frequency ωstab of the critical mode, when analyzing the threshold of stability. After the mathematical description is shown, a numerical example of a 2-pole induction motor (power rating 2.4 MW) is presented, in which the threshold of stability is analyzed as well as the forced vibrations due to dynamic rotor eccentricity by investigating the bearing housing vibrations, the foundation vibrations and the actuator forces.