Balancing of a Rotor with Active Magnetic Bearing System: Comparison of One-and Two-Plane Balancing Procedures

Abstract

Rotor balancing is a procedure used to reduce the unbalance vibration of rotating machinery. Unbalance vibration creates forces to the bearings and causes harmful effects such as reducing their lifespan. Unbalance is caused simply because of the difference of the rotors axis of inertia and the rotating axis. In this paper, two balancing techniques are presented to reduce the unbalance vibration: one-plane balancing procedure used for two-plane balancing and a two-plane balancing procedure. Both balancing procedures take into account the cross effect between the planes. Rotor levitated with active magnetic bearings is balanced. Magnetic levitation is unstable so the xy-position of the rotor is measured on both rotor ends for the control purposes. The unbalance vibrations are analyzed from these position measurements so no additional hardware is required for the rotor balancing. Results are presented from a simulation model of an active magnetic bearing system. Comparison of the one-plane and two-plane balancing is provided.