Static mass imbalance identification and vibration control for rotor of magnetically suspended control moment gyro with active-passive magnetic bearings

Identification of the static mass imbalance is critical to the control of magnetically suspended rotors. A static mass imbalance identification method without using the closed-loop transfer function is proposed in this paper. Then the null displacement control of the magnetically suspended rotor is realized by using the identified static mass imbalance. Because null vibration is the control target for the rotor of a magnetically suspended control moment gyro (MSCMG) with active-passive magnetic bearings, a null vibration control method depending on the displacement stiffness is introduced. However, the displacement stiffness of the passive magnetic bearing is hard to obtain accurately. Therefore, the least mean square method is utilized to adjust the uncertain displacement stiffness adaptively according to the centroid acceleration. Simulation results show that adaptive null vibration control based on the static mass imbalance identification can remove the synchronous magnetic bearing force effectively, thus enabling the rotor of the MSCMG with active-passive magnetic bearings to rotate about its initial axis.