Unbalance vibration control of magnetic bearing systems using adaptive algorithm with disturbance frequency estimation

This study is concerned with the adaptive forced rejection approach for a single periodic output disturbance with an unknown period and its application to unbalance vibration suppression in rotor-magnetic bearing systems. A discrete recursive technique is applied to estimate the unknown disturbance period and then to internally and adaptively generate a pseudofeedforward reference signal such as that this disturbance is eliminated. Simulations are carried out. The results indicate that both the estimation algorithm of an unknown period and reference signal adaptive generation algorithm are stable. Finally, the approach is applied to a problem of unbalance vibration suppression in rotor-magnetic bearing systems. Approximately 20 dB and 7 dB reductions in unbalance vibrations were experimentally obtained in the horizontal and vertical directions of the front and rear sides of the rotor, respectively, The experimental results show that the proposed algorithm is effective for achieving unbalance vibration suppression.