Vibration control of soft mounted induction motors with sleeve bearings using active motor foot mounts: a theoretical analysis

Abstract

In the paper, the vibration control of induction motors with sleeve bearings—mounted on soft steel frame foundations—using active motor foot mounts is analyzed. The presented model is based on a multibody model, considering electromagnetic influence, stiffness, and rotating damping of the rotor, stiffness and damping of the bearing housings with end shields, of the oil film in the sleeve bearings, and of the foundation. Additionally, the stiffness and damping of the motor foot mounts—which are positioned between the motor feet and the steel frame foundation—are considered, as well as the controlled forces which are applied in the vibration system by the motor foot mounts, using PD-controllers. The aim of the paper is to unite all these influences in a mathematical model, including the control system. Based on a numerical example, it can be shown that the vibration behavior of soft mounted induction motors can be clearly improved and that critical speeds in the speed range can be avoided, using active motor foot mounts.