Parameter Desgin And Control Research On Inverter Driven Six-Pole Radial-Axial Hybrid Magnetic Bearings

The magnetic bearing is a new type of support device which uses Maxwell force to make rotor suspension stably and realizes no mechanical contact between rotor and stator.The magnetic bearing has a series of advantages such as no friction,no wear,no lubrication,no pollution,high speed,high precision and working in ultra-clean environment,so it has broad application prospects in life science,energy transportation,industrial manufacturing,aeronautics and astronautics and other fields.The conventional four-pole or eight-pole magnetic bearing has the disadvantages of large volume,high driving cost and large power loss,and the further development and application are limited.In contrast,the inverter driven six-pole radial-axial hybrid magnetic bearing is driven by a three-phase inverter,which has the advantages of small volume,compact structure and low power loss.Supported by the National Natural Science Foundation of China(51675244)and the Key Research and Development Program of Jiangsu Province(BE2016150),this dissertation takes the inverter driven six-pole radial-axial hybrid magnetic bearing as the research object.The main contents are as follows:1.In this dissertation,the research and development of magnetic bearings at home and abroad are summarized,the magnetic bearings according to the different structures are classified,and the advantages and disadvantages of each kind of magnetic bearings are analyzed.The present research status of magnetic bearing control technology is summarized,and the purpose and significance of this subject are clarified.2.The structure and working principle of the traditional three-pole radial-axial HMB are described,and its mathematical model is deduced by using the equivalent magnetic circuit method.It is found that due to the asymmetry of the three-pole structure,the force-current characteristics of the three-pole structure have the feature of strong coupling and non-linearity,and a space-symmetric six-pole structure is proposed.The structure and working principle of the six-pole structure are introduced.The mathematical model is deduced by using the equivalent magnetic circuit method.Through theoretical analysis and finite element simulation,the force-current characteristics and maximum bearing capacity of the three-pole structure and the six-pole structure are obtained respectively.The results are compared and analyzed to verify the superiority of the six-pole structure.3.A neural network inverse system decoupling control method for inverter driven six-pole radial-axial HMB is proposed by combining the inverse system control method with neural network.Based on this method,the inverter driven six-pole radial-axial HMB is proved to be reversible.Based on the Matlab/Simulink platform,a neural network inverse control system is built to verify the reliability and robustness of the system.4.A inverter driven six-pole radial-axial HMB digital control platform is designed.The design scheme of three-phase power drive module,axial power drive module and displacement conditioning circuit are given.The beginning suspension experiment and anti-interference experiment of bearing rotor are carried out.The experimental results show that the proposed magnetic bearing can achieve stable operation.