Speed Sensorless And Fault Tolerant Control Of A Bearingless Induction Motor

A bearingless induction motor(BL-IM)is a new type of motor that realizes rotor rotation and self-suspension at the same time,which adds a set of suspension windings to the stator of an induction motor by taking advantage of the similarity between the structure of the induction motor and the magnetic bearing stator.The BL-IM has the advantages of high-speed,super-speed,frictionless,high life and so on,which has highlighted the extremely important application value in high-speed and ultra-high-speed equipment applications,harsh environment drive,in the life sciences special needs transmission and other fields.With the financial support of the National Natural Science Foundation of China,the research in this dissertation was carried out with respect to the BL-IM operation principle,mathematical model,speed sensorless operation,sensor fault-tolerant control and digital control system implementation.The main work and results obtained are as follows:Firstly,the research background of the BL-IM,the current status of domestic and international research,the future development prospects and application areas are reviewed.Based on this,the research on speed sensorless and sensor fault-tolerant control is elaborated.A mathematical model of the BL-IM is derived based on its operation principle,on which an air-gap magnetic field orientation control system is constructed to lay the foundation for speed sensorless and fault-tolerant control of the BL-IM.Secondly,to solve the adverse effects of parameter changes and external disturbances on the accuracy of speed sensor speed feedback in the actual operation of the BL-IM,a speed sensorless control strategy combining neural network and fractional sliding mode is designed.The strategy combines fractional order theory with a sliding mode observer,and then joint radial basis function(RBF)neural network to compensate for the observation error,thus effectively improving the stability and anti-disturbance of the speed observer.Thirdly,to solve the problem of speed and current sensor failures which easily occurs when the BL-IM is used in complex and harsh environments,a fault-tolerant control strategy for speed and current sensors is designed.The strategy first uses the expansion observer and data fusion principle to achieve fault diagnosis and fault-tolerant control of the speed sensor,and then uses the compensated current state equation in different coordinates to achieve fault diagnosis and fault-tolerant control of the current sensor.Thus,it effectively improves the reliability of speed and current sensors.Finally,based on the core controller TMS320F2812 DSP,a BL-IM digital control platform is constructed and experimental studies are carried out on its speed,current and suspension characteristics.The experimental results show that the designed control system not only achieves stable rotation of the BL-IM,but also maintains good suspension of the rotor.