Study On Nonlinear Decoupling And Control For Bearingless Induction Motors

The bearingless motor, which combines function of motor and magnetic bearing, is a novel special type motor. The bearingless motors have many advantages, such as compact structure, higher reliability and shorter shaft length, etc. For these advantages, they have good application prospects in high-speed drives. In recent years, for the unique suspension principle and structure, bearingless motors have been developed for aeronautics and astronautics, high technology energy resources, semiconductor manufacturing industries, food processing industries, biologic medicinal engineering, etc..Firstly, based on the analysis to all kinds of bearingless motor and magnetic bearings' structures and magnetic circuits, an innovated 5 degrees of freedom bearingless induction motor is proposed, which is composed of a 3 degrees of freedom axial-radial magnetic bearing and a 2 degrees of freedom bearingless induction motor. The configuration and working principle also have been introduced, then the mathematics models of 5 degrees of freedom bearingless induction motor are deduced.Secondly, Because the 5 degrees of freedom bearingless induction motor is a multi-variable, nonlinear and strong-coupled system, a method based onα-th order inverse system theory has been used successfully in realizing dynamic decoupling control among radial displacement subsystems and torque (speed) subsystem. And this method is realized that each subsystems not only have no coupling, but also all subsystems have been linearized, therefore we design the system and attain the ideal performance easily. Then, linear control system techniques are applied to these linearization subsystems to synthesize and simulate.Thirdly, the traditional bearingless induction motor control method have been researched, a flux observer and an independent controller of bearingless induction motor based on Neural network inverse have been designed. Then, study on the wholeradial displacement control system of bearingless induction motor.Finally, both the hardware and software system based on digital signal processor (DSP) have been designed, the flow charts for main program and interrupt programs have been listed too. The experimental test rig is constructed and the detailed testing procedures have been proposed, which establishes a good foundation for the next parameters debugging and function test.The theory research and simulation results have shown that neural network inverse system theory has succeed in realizing dynamic decoupling control for the 5 degrees of freedom bearingless induction motor, which is a multi-variable, nonlinear and strong-coupled system. The research results, such as arithmetics of decoupling control, experiment rig, experiment scheme, etc., have established better foundation for future researching on bearingless induction motor.