Abstract: In a momentum wheel system suspended by active magnetic bearings, the stability of the system is influenced by two severe resonances coming from the structure of the system at a middle frequency band. Special controller designs are used to restrain them. A non-parametric frequency domain method is used to identify the system model to obtain structure vibration information. It is found that the frequency of one of the structure resonances varies markedly with controller stiffness. Modeling the resonances is difficult, and a convenient method based on an iterative process of identification and controller parameter tuning is used to deal with the resonances. In controller designs of the process, a zero-pole pair method and a μ-synthesis method are applied respectively. The experiments show that the iterative process is effect and two controllers designed by the two methods respectively are both suitable for restraining the structure vibrations.

Key words: Active magnetic bearing, Flywheel, Vibration control