Self-excited vibration depression of high-speed rotor in magnetically suspended control moment gyroscope

In magnetically suspended control moment gyroscope (CMG), self-excited vibration of high-speed rotor is one of principal factor which effects stability of active magnetic bearing (AMB) system, This vibration can be depressed by means of inserting notch filter (NF) into AMB controller, but it is very difficult to decide NF parameters since vibration frequency is also changed by NF insertion or variety of NF parameter and rotor speed. This paper proposed a new method based on precisely modeling flexible mode of rotor and close-loop simulation to optimize NF center frequency and to determine damp span of NF poles. To achieve this purpose, it is necessary to reduce flexible modes, only the first order one remained, so that all parameters corresponding to flexible mode can be fit precisely using experimental data from statically suspended rotor. With this model based on precise parameters, frequency and stability of flexible mode in the magnetically suspended rotor were simulated and suboptimum center frequency and damp span of NF was selected. Notch-filter with this center frequency was utilized in a magnetically suspended CMG rotor, which achieved 24000 r/min without any self-excited vibration. Effectiveness of the proposed method is verified through simulations and experiments.