Control Study For Compensating Rotor Vibration Of Five-dof Six-pole Hybrid Magnetic Bearings

As proposed in the national "The 14 th Five-Year Plan",China aims to enter the ranks of world manufacturing powers in 2025 and become a true manufacturing power in 2035.Computer numerical control machine tools,as a key component of the manufacturing industry,have been rapidly developed under national incentives.However,as the core of computer numerical control machine tools,most of China’s high-speed electric spindles rely on imports,so it is necessary to increase research in the field of high-speed electric spindles.As a traditional support component for electric spindle,when the shaft runs at high speed,mechanical bearings have shortcomings such as friction and wear,high energy consumption,and short service life.However,magnetic bearings that rely on the generation of magnetic field force to support the shaft do not come into contact with the shaft,have no friction wear,and are suitable for higher speed environments.Therefore,magnetic bearings are regarded as the development direction of electric spindle support components.The magnetic bearing is a new type of support bearing,it can rely on generating magnetic force to offset the gravity of the rotor,so that it can be stably suspended in the position of the geometric center.There is no mechanical contact between the rotor and the stator.The magnetic bearing has no friction,no pollution,high speed,high precision,no need for lubricating oil and so on.The magnetic bearing will replace traditional bearings in more fields,especially for vacuum,ultra-clean,ultra-high-speed,aerospace,nuclear energy and other fields with high requirements.In order to reduce the strong coupling and nonlinearity in the operation of three-pole HMB,a five-degree-of-freedom(5-DOF)six-pole hybrid magnetic bearing(Hybrid magnetic bearing,HMB)is proposed as the research object.A six-pole radial HMB and a six-pole radial-axial HMB are installed at both ends of the rotor.The mathematical model and parameter design and the state equation of the 5-DOF six-pole hybrid magnetic bearing and the compensation control of the rotor unbalanced vibration are analyzed theoretically and experimentally.In the dissertation,the main work and achievements are as follows:(1)The research background and significance of magnetic bearings are described.The working principle,application prospects,classification,and structural characteristics of magnetic bearings are introduced.According to the research status of magnetic bearings,it is introduced both domestically and abroad.The research status of magnetic bearings rotor unbalance vibration control method is introduced.The purpose and significance of the research are discussed,and the content arrangement of each chapter are explained.(2)The overall structure of the research object in the dissertation was introduced,and two magnetic bearings component at both ends of the rotor were introduced.The parameter design and mathematical modeling of the two magnetic bearings were carried out,and the structural rationality was analyzed through finite element simulation.The state equation of 5-DOF six-pole HMB is constructed.(3)In order to avoid the impact of rotor vibration on operating accuracy,the six-pole radial HMB at one end of 5-DOF six-pole HMB rotor is taken as the research object.The causes of rotor unbalanced vibration are discussed,and the vibration laws of the rotor are studied;The Versoria function model is introduced to control the step size of the LMS algorithm,and the fuzzy inference machine is used to control the curve adjustment parameters in the Versoria function model,and the adaptive least mean square(LMS)filtering algorithm is improved,while taking into account the tracking speed and steady-state error during the convergence process.The simulation analysis is conducted using MATLAB,and the results show that the proposed variable step size LMS adaptive filter can greatly improve the effect of rotor vibration compensation.(4)In order to better control the movement of the rotor,the digital control system of the5-DOF six-pole HMB is designed,including software and hardware parts.An experimental platform is constructed to complete the rotor levitation,rotor stable levitation,and load experiments.The dynamic and static performance of the 5-DOF six-pole HMB is analyzed.