Research On Active Vibration Control For Magnetically Suspended High-speed Motor

In view of the advantages of small volume,high power density and high efficiency,the high-speed motor has been widely used in many industrial applications.However,the undesired vibration force of the motor under high-speed operating conditions will not only lead to the degraded performance,but may even result in system instability in severe cases.Taking advantage of the active control capability of magnetic bearings,this thesis is aimed to attenuate the vibration of the motor casing.The active vibration control method for the magnetically suspended high-speed motor is studied,and experimental research has been conducted.Considering the synchronous vibration caused by mass imbalance of the rotor,the synchronous vibration suppression algorithm based on the optimal notch filter is proposed.This method can effectively attenuate the synchronous vibration force,eliminate the synchronous control current and suppress the rigid body resonance of the rotor.In order to improve the dynamic performance of vibration suppression,the phase angle of the phase-shift notch filter is taken as the optimization parameter,and the objective function is proposed based on the integral of time-weighted absolute current.Then the design process of optimizing the phase angle is given.Optimal notch filter can improve the dynamic performance of the current suppression,so that the dynamic response of the vibration suppression is optimal.In regard to the multi-frequency vibration resulting from sensor runout,the multi-frequency vibration control method based on the multiple phase-shift notch filters is studied.Compared with the parallel notch filters,which is commonly used in the literatures,the control system with multiple phase-shift notch filters connected in cascaded mode is proposed and the system stability is analyzed.It is proved that the cascaded mode control system and the parallel mode control system share the same stability conditions.Moreover,theoretical analysis has demonstrated that the proposed cascaded mode control system could achieve the same suppression effects as the parallel mode control system.Finally,the experiments have been carried out on the magnetically suspended high-speed motor.On one hand,it is validated by the experimental results that the synchronous vibration suppression method based on the optimal notch filter can improve the dynamic performance of the control system,and the suppression effect on the synchronous vibration force is significant.Moreover,the power consumption of the magnetic bearing control system is reduced,and the rigid body resonance of the rotor is suppressed.On the other hand,it is verified by the experiments that the control system with cascaded mode notch filters and that with parallel mode notch filters can both effectively attenuate the multi-frequency vibration force,and the suppression effects are the same.