Study On Automatic Balance Compensation Control Of Active Magnetic Bearing

The rotor has problems such as machining error,material unevenness,dynamic balance residue and so on,making the unbalance generally exist in the rotating machinery,causing the system to produce unbalanced vibration,the frequency is the same as the frequency of the speed.Vibration is generated by the rotor and transmitted to the outside of the housing through the bearing,which affects its reliability and also interferes with the normal operation of other surrounding equipment.Therefore,in order to give full play to the advantages of active magnetic bearing control,the use of compensation algorithms to reduce the impact of unbalanced vibration on the active magnetic suspension system and peripheral equipment is of great significance to promote the industrial application of active magnetic bearings.This paper focuses on the causes of external vibration of active magnetic bearings and the compensation control algorithm.The specific research contents are as follows:Independently designed and built a set of 5-DOF magnetic bearing experimental system,which mainly includes mechanical structure part,electrical hardware part,platform monitoring part and control algorithm part.Through the finite element modal analysis of the rotor,the critical speed of the rotor is obtained;through the finite element analysis of the magnetic bearing,the maximum load capacity of the theoretical calculation is verified;the simulation model of the magnetic bearing control system is established through Simulink software,and the rotor is simulated.Parameters such as axis trajectory and bearing external force during floating and static levitation.The dynamic equation of the magnetic bearing rotor is established.Taking into account the existence of unbalance,the trajectory of the magnetic bearing unbalanced rotor axis is obtained through calculation,and the reason for the external force transmission of the radial magnetic bearing is analyzed.Due to the imbalance,the geometric axis of the rotor does not coincide with the principal axis of inertia,causing the rotor to rotate around an unknown axis other than the principal axis of inertia and the geometric axis.The axis trajectory presents a ring shape and produces vibrations at the same frequency as the rotational speed.By adding the consideration of the imbalance in the Simulink simulation model of the active magnetic bearing,the correctness of the theoretical analysis is verified.Discuss the feasibility of automatic balance compensation for the rotor by eliminating the controller’s control effect on the rotor unbalance.An adaptive notch filter is used to filter out the same-frequency components of the rotational speed in the rotor axis track,so as to achieve the purpose of weakening the controller’s control of the rotor unbalance,so that the rotor rotates around its main inertia.The reason for the residual displacement stiffness force is analyzed.Based on the automatic balance compensation algorithm realized by the adaptive notch filter,a residual displacement stiffness force compensation method suitable for horizontal rotors is proposed,which can effectively suppress The external vibration of the magnetic bearing is analyzed and it is concluded that the compensation method is also applicable to the vertical rotor.