Research On The Sensorless Control System Of Bearingless Induction Motor

Bearingless induction motor is a new type of motor integrating magnetic bearing and ac motor functions.In order to obtain better control performance of magnetic levitation operation,it is necessary to obtain the speed feedback signal in real time.However,the mechanical speed sensor is difficult to install and easy to be disturbed by the environment.In this paper,Bearingless induction motor is taken as the research object,and on the basis of its inverse system decoupling control,the sensorless control is mainly studied.The main research contents of this paper include the following aspects:(1)The mathematical model of the bearingless induction motor is established,and the inverse decoupling control method is adopted to achieve the decoupling of the variables of the bearingless induction motor.(2)For bearingless induction motor without speed sensor control problem,the shortcomings of model reference adaptive system speed observation method based on rotor flux are analyzed.On this basis,the flux voltage model of torque windings is improved;Based on the sliding mode variable structure theory,a sliding mode variable structure-model reference adaptive rotational speed observer is studied.Simulation results show that: the designed speed identification method of sliding mode variable structure-model reference adaptive,can obtain better speed observation,Bearingless induction motor can achieve the goal of without speed sensor control.(3)In order to improve the robustness of speed identification to motor parameters,the sliding mode observer was used to directly estimate the rotor flux,and on this basis,the online identification expression of the speed was derived,and the stability of this observer was proved by using lyapunov theory.The system simulation results show that better rotor flux and speed observation performance can be obtained.(4)In order to make use of the advantages of simple and easy to use model reference adaptive system method,and overcome the shortcomings of model reference adaptive system method based on rotor flux,the model reference adaptive system method based on reactive power was studied for speed identification.The stability of this method is proved theoretically.On this basis,the rotor resistance identification method based on reactive power is studied,and the relevant parameters in the control system are corrected by using the rotor resistance identification results.Simulationresults show that the model reference adaptive system speed and rotor resistance observation method based on reactive power has better observation effect.After correcting the observed rotor resistance to the control system for the relevant parameters,the bearingless induction motor can achieve better operation control effect.