Research On Rotor Disturbance And Vibration Compensation Control Of A Bearingless Induction Motor

A bearingless induction motor(BIM)organically combines asynchronous motor with magnetic bearing to simultaneously achieve rotor rotation and suspension.The BIM has the advantages of low cost,simple structure,uniform air gap,no friction,no wear,and easy flux-weakening control.It has great value of theory and practical application in high-tech fields,such as CNC machine tools,aerospace and medical equipment.With the support of the National Natural Science Foundation of China(51475214),the operation principle of the BIM,the generation mechanism of radial suspension force,the establishment of mathematical model,the anti-disturbance control of rotor,the cause of rotor unbalanced vibration and its compensation control,and the design of digital control system are studied.The major contents are as follows:(1)The research background and status of the bearingless motor are expounded,the research status,development trend and application field of the BIM are summarized.Besides,the active disturbance rejection control(ADRC)technology and vibration suppression technology are introduced.Based on the analysis of the basic structure and operation principle of the BIM,the mathematical model is established,and the air-gap magnetic field oriented decoupling control system of the BIM is also constructed to lay the foundation for rotor disturbance and vibration compensation control.(2)To solve the problem of radial disturbance caused by the uneven rotor mass distribution and load variation of the BIM,a radial disturbance control strategy for the BIM based on improved ADRC is proposed.The cubic interpolation method is used to fit the nonlinear function of the ADRC,which improves the performance of the controller.Meanwhile,the disturbance observer is designed and applied to the suspension system,and the observed disturbance acceleration is compensated in the form of current,which can effectively suppress the rotor radial disturbance and improve the suspension performance of the BIM.(3)To handle the unbalanced vibration due to the rotor mass eccentricity of the BIM,an unbalanced force feed-forward compensation controller and current compensation link are designed.The vibration signal with the same frequency as the rotational speed is extracted by the synchronous signal detection unit,and then the compensating force component is generated by the feed-forward compensation controller.In addition,the current induced by the suspension winding in the rotor is considered into the suspension system through the current compensation link,which can effectively reduce the rotor radial displacement and restrain the unbalanced vibration.(4)A BIM digital control system with TSM320F2812 DSP as the control core is established and the experimental research is carried out.The experimental results show that the designed control system not only has good speed response,but also has good suspension characteristics and anti-disturbance ability.