Research On Control Strategy Of Periodic Vibration Of Active Magnetic Bearing Rotor

Magnetic suspension bearings are a new type of non-contact support components widely used in machining,aerospace,vacuum technology,rotor dynamics identification and testing,and are recognized as promising new bearings.However,due to the uneven distribution of material quality and processing error,the rotor mass distribution is uneven,and periodic vibration will occur during rotation,which seriously affects the performance and safe operation of the rotor system.Therefore,suppressing the periodic vibration of the magnetic bearing rotor is the key to improve the system operation accuracy,and it is also the focus of this paper.Aiming at the periodic vibration problem of the rotor of high-speed magnetic levitation motor,the research idea of this paper is to establish magnetic bearing system model and rotor periodic vibration model by analyzing the magnetic bearing system.Starting from the causes of the periodic vibration of the magnetic bearing rotor,the control strategy for suppressing the periodic vibration is proposed and verified by simulation.In order to further verify the effectiveness of the proposed control strategy,a magnetic bearing digital controller is designed to verify the control strategy proposed in this paper.This paper has completed the simulation verification of the control strategy,the design of the digital controller and its practical verification.The control strategy proposed in this paper has not been tested and verified.The specific research contents are as follows:(1)The working principle of the magnetic bearing system is expounded.The mechanical structure of an active magnetic bearing is introduced.The characteristics of the suspension force of the magnetic bearing rotor are analyzed,and the mathematical model of the magnetic bearing system is built.The unbalanced force model of the magnetic bearing rotor was established and the periodic vibration characteristics of the rotor were analyzed.(2)It is proposed to apply the linear active disturbance suppression control strategy and the repetitive control strategy to the magnetic bearing control system.The working principle of the linear auto disturbance rejection controller and the repetitive controller are introduced respectively.The two controllers are combined to form a composite controller.According to the different controller positions,the composite controller has two combined structures:embedding Type and parallel type.The embedded and parallel composite control structures were compared in detail to improve the anti-disturbance capability of the system.The selection of the composite controller structure was completed and the control parameters were set.(3)The mathematical model of the magnetic bearing control system based on the composite control structure is established and verified by simulation.The simulation results show that the composite controller not only has the steady-state performance of the linear ADRC controller,but also can effectively suppress the periodic vibration of the rotor.At10kr/min,the rotor is applied with a magnitude of 200 N and the same speed.With periodic disturbances,the peak value of the periodic vibration of the rotor is reduced by 69.2%.(4)The magnetic bearing digital controller based on TMS320F28335 is designed,and the static suspension experiment of the high-speed magnetic suspension motor is carried out with the PID control strategy as the core algorithm.The stable suspension of the rotor at the equilibrium position is realized.The practicality of the digital controller designed in this paper.