Unbalance compensation for active magnetic bearings using ILC

A PID control strategy with compensation of unbalance due to centrifugal forces using a learning strategy is presented for an active magnetic bearing. Experimental results are included, which show good performance with tracking of the disturbance in a wide range of shaft velocities. Experiments were performed with different methods to elliminate the undesirable high frequency components from the compensating signal and to allow changes in magnitude and frequency of the perturbation: a) Using a forgetting factor, and b) using a noncausal low-pass filter.