Unbalance Compensation of a Magnetically Levitated Rotor for the Whole Operating Range

Unbalance vibration of magnetically levitated rotors can lead to instability caused by saturation of the actuators. Further the rotor orbit can increase to not acceptable values. To overcome this problem of the presented paper an unbalance compensation for rotors with a high unbalance even in the low frequency range was developed. The controller consists of two different approaches based on generalized notch filters. The parameters of the filter are dependent on the angular frequency and can be easily evaluated off-line and stored in a look-up table or implemented as a linear approximation. The robustness for different angular velocity ranges is determined in this paper. Also the dependence of the stability on the parameter of the proposed compensation is illustrated. The proposed approach has advantages in terms of calculating the closed loop stability due to the linear nature and in terms of run time and complexity. Experimental results of the developed unbalance compensation on an industrial system are included.