Research On Bearingless Induction Motor And Its Model Predictive Control

The bearingless induction motor(BIM)skillfully combines traditional induction motor with magnetic bearings and adds a suspension winding on the stator winding of traditional induction motor to achieve suspension and rotation at the same time.This motor not only has the characteristics of magnetic bearings supporting motor,but also has the advantages of no lubrication,no wear,simple structure,high reliability,uniform air gap and easy to weaken magnetic field.The BIM has a wide application in aerospace,biomedicine,chemical industry and other fields.It is one of the most valuable bearingless motor types.In this dissertation,with the support of General Program of National Natural Science Foundation of China(51475214),the working mechanism of BIM,the establishment of mathematical model,model predictive current control based on limitation of current error in torque part,direct levitation force control based on model prediction in suspension part and realization of digital control system are discussed.The main contents are summarized as follows:(1)The research background,research status at home and abroad,development trend and application prospect of the BIM are summarized.The basic situation of model predictive control is briefly summarized.On the basis of mathematical model of the BIM,the air gap magnetic field oriented control system is designed,which lays a foundation for further high performance model predictive control of the BIM.(2)Aiming at the problems of current distortion and inaccurate parameter observation in traditional vector control algorithm of BIM,a model predictive current control strategy based on limitation of current error in the torque part is designed,and a delay compensation link and a full-order observer are added to improve the accuracy of parameter observation,speed up the convergence of the BIM,and improve the lag problem of the system.(3)In order to improve the suspension performance of the BIM,the direct suspension force control based on model prediction is adopted in the suspension part of the BIM.The objective function of flux linkage is constructed.An improved flux observer is introduced to improve the accuracy of parameter observation and the control accuracy of the system.(4)A digital control system platform based on DSP is constructed.Experiments on motor speed response,current and rotor trajectory are carried out.The experimental results show that the designed control system can achieve stable rotation and suspension of the motor,and improve the response performance and operation quality.