Sliding Mode Variable Structure Control For Bearingless Motors With Rectifying Circuit

Bearingless motors make use of the comparability on structure of magnetic bearing motor.Magnetic bearing winding which can produce levitation force is embedded into the armature core of rotating motor,so the rotor of the motor can rotate and levitate by itself. This article analyzes bearingless motors with rectifying circuit based on the working principle, to establish the mathematical model, and the effect on the rotor of levitation force is controlled. This paper mainly content as follows:(1)Introduce the domestic and international research situation, characteristics, classification, structure and its industrial application of bearingless motor, such as blood pumping system, bearingless PTFE pumps for semiconductor manufacturing,etc.(2)This paper analyzes on the bearingless motor lorentz force,electromagnetic torque and the formation of the maxwell’s force, that bearingless motor suspension mechanism, and produce stable controllable maxwell’s basic conditions of the radial electromagnetic force.(3)This article researches the existence conditions and accessibility conditions of sliding mode variable structure control,and this paper analyzes the design of the switch function, system dynamic quality, sliding model variable structure control of the basic methods and chattering phenomena. Prove the discrete sliding mode variable structure control system of existence, accessibility and not degeneration of the discrete system.(4)This paper describes the principle of bearingless motors with rectifying circuit as a basis,then establish its mathematical model and control the levitation force on rotor.Sliding mode variable structure control has invariance with the model perturbation and interference,but this method can easily produce chattering phenomenon,thus affecting the accuracy of the system control and increasing the energy consumption of the system,the control method of reaching law can restrain the influence of chattering effectively,so use sliding mode variable structure control based on reaching law to control levitation force of bearingless motors is proposed. Through the simulation experiment in MATLAB, the correctness of this method is verified.