UNBALANCE COMPENSATION USING GENERALIZED NOTCH FILTERS IN THE MULTIVARIABLE FEEDBACK OF MAGNETIC BEARINGS

Unbalance of magnetically levitated rotors causes undesirable synchron ous vibrations which may lead to saturation of the magnetic actuator, To avoid this problem we propose a generalized narrow-band notch filte r which is inserted into the multivariable feedback without destabiliz ing the closed loop, The parameters of the generalized notch filter st rongly depend on the inverse sensitivity matrix evaluated at rotationa l speed. This matrix is easily measured a priori and stored in a look- up table. It is shown that a decentralized notch is feasible for weakl y gyroscopic rotors, The proposed notch filter approach has advantages in terms of runtime complexity and analytical verification of closed- loop stability. Results from the implementation of the proposed unbala nce compensation in industrial magnetic bearing systems are included.