Research On Unbalanced Vibration Decoupling Control Of Bearingless Induction Motor

The bearingless asynchronous motor has the characteristics of magnetic bearing motor and asynchronous motor at the same time.However,due to the non-uniform distribution of materials,assembly precision,dimensional deviation,etc.,it is inevitable that the center of mass and the geometric center of the stator do not coincide,resulting in unbalanced vibration of the rotor and affecting the rotor.Magnetic suspension control accuracy.When the rotational speed is high,if the displacement signal measured by the displacement sensor is all fed back to the displacement controller,the magnetic suspension inverter will be saturated.Therefore,it is extremely important to study the unbalanced vibration of bearingless asynchronous motors.This paper will focus on the unbalanced vibration problem of bearingless asynchronous motors.The main research contents can be summarized as follows:Firstly,the mathematical model of the bearingless asynchronous motor system,the inverse system mathematical model,and the inverse system decoupling control method are analyzed by the traditional motor motion equation and the nonlinear strong coupling characteristics of the bearingless asynchronous motor.Then,the control method based on the minimum principle of rotor unbalanced vibration displacement is studied.The unbalanced displacement of the rotor is extracted by the ’coordinate transformation + low-pass filtering’ method,and the feedforward compensation is applied to the rotor displacement closed-loop control system to improve the rotor magnetic levitation control accuracy.Combined with the frequency characteristics of unbalanced displacement,the unbalanced displacement LMS extraction algorithm based on the new step function is studied.The adaptive LMS filter is constructed.The extracted unbalanced displacement feedforward is compensated to the rotor displacement closed-loop system to improve the rotor.Suspension control accuracy.Secondly,the vibration control method based on the principle of minimum current of unbalanced current is studied.Aiming at the problem that the magnetic levitation control current is too large due to the unbalanced vibration of the bearingless asynchronous motor at high speed,it is easy to cause the magnetic levitation inverter saturation problem.The unbalanced displacement of the rotor is extracted by the adaptive LMS algorithm,and the corresponding PID regulator is generated.Balance the vibration compensation force,and then generate the unbalanced vibration compensation current through the “force/current” transformation.Finally,the unbalanced vibration compensation current feedforward compensation is applied to the magnetic levitation current control system to suppress or eliminate the unbalanced radial excitation transmitted to the stator.Vibration,suppressing unbalanced vibration of the stator.Finally,the simulation model was built and the system simulation analysis was carried out.The simulation results show that the new step size factor of ’coordinate transformation + low-pass filtering’ and adaptive LMS filter can realize the fast and accurate extraction of unbalanced vibration displacement of the rotor.By means of the feedforward compensation of unbalanced displacement,the unbalanced virbation of rotor can significantly suppressed;through the feedforward compensation of the unbalanced vibration compensation current,the amplitude of the magnetic levitation control current can be effectively suppressed while ensuring that the rotor unbalance vibration does not exceed the safety distance.