Research On Stator Flux-Orientation Control For Bearingless Induction Motor Based On Speed Sensorless

The bearingless motor which integrates motor and magnetic bearing, has the function of rotation and self-levitation.Different from the traditional suspension principle of magnetic suspension motor,the bearingless motor winds the levitation windings together with conventional motor windings to produce radial forces by taking advantages of the similarity between the structure of magnetic bearing and that of the AC motor.The rotor shaft can be successfully suspended by the electromagnetic forces.It has been the focus of research work on high speed motor since 1990's.The self-bearing induction motor is a strong-coupled,nonlinear, multi-variable complicated system.This dissertation focuses on the fundamental theory and experiments of self-beating induction motor including mathematic models,flux oriented controller,speed sensorless technology and the digital control system design.The detail contents are as follows:Firstly,the principle of radial suspension force is expounded.The mathematic models of radial suspension forces and rotation part of the self-bearing induction motor are deduced.In order to realize the decoupling control of torque and radial suspension forces for self-bearing control are designed,this dissertation brings forward the decouping method of stator flux oriented control,designs the obercation of self-accommodation flux.If the motor works on the low speed,this observation will use the I-ωmodel,or else the observation will use the U-I model.The this method realizations the observation of flux in full career.The suspend-rotator uses the feedback of suspend force system,combines the suspend-force to the unilateral magnetic force,in order to receive the factly control force.The radial-rotator adopts the control method with direct solution of d-axis current.This control system is simulated with Matlab/Simulink toolbox.Simulation results have shown that rotor can suspension steadily,toque and radial suspension subsystems can operate independently.Secondly,this dissertation adwances the sensorless vector control on induction motor with extended kalman filter(EKF),the speed sensorless flux oriented systems of self-bearing induction motor are established. Using Matlab/Simulink toolbox,the simulation model is established.It can be seen that the control system has good performance by simulation in different speed.At last,based on the principle of stator flux oriented control,the digaital control system is designed using TMS320F2812DSP,and the flowcharts of each functional block are presented.