Research On Nonlinear Decoupling Control Of The Bearingless Induction Motors

The bearingless induction motor,which integrates induction motor and magnetic bearing,has the function of rotation and self-levitation.It has been the focus of research work on high speed motor since 1990's.This dissertation focuses on the linearization decoupling control of Bearingless Induction Motor.The mathematical model of Bearingless Induction Motor is proposed based on the analyses of magnetic suspension principle.As the bearingless induction motor is a strongly coupled complicated nonlinear system,the decoupling control of electromagnet torque and radial levitation force is the base of the stable operation of bearingless motor.First,flux orientation controller is proposed to realize the levitation of rotor.Experimental and simulation results show that,after using the air-gap flux-orientation controller,rotor flux-orientation controller and the stator flux-orientation controller,the system has good static and dynamic performance each time,the electromagnetic torque and levitation force is really decoupled.The Bearingless Induction Motor is a nonlinear system with significant coupling.This dissertation applies the precision linearization theory.The appropriate coordinate transformation and nonlinear state feedback are obtained through Lie deriving the output variable,with which the BIM system is input-output liberalized,Furthermore,which realizes the completely dynamic decoupling.Simulation results indicate that this algorithm approaches the ideal performance while the load is changing.At last,a digital control system for real-time control is designed with DSP(TMS320F2812).According to the principle and characters of bearingless induction motor,design speed model and displacement model respectively.