| A Bearingless Induction Motor(BL-IM)combines the advantages and functions of magnetic bearings and traditional induction motors.It can operate without bearing support in vacuum environment,corrosive environment,high speed and other special environments.It is one of the most valuable bearingless motors.In this dissertation,the operation mechanism of the BL-IM,mathematical model,rotor unbalanced vibration compensation control,rotor displacement sensorless control and digital control system are studied.The main work and achievements are as follows.Firstly,the research background and research status of bearingless motor at home and abroad are introduced,and the development trend and application field of the BL-IM are further introduced.On the basis of analyzing the operation principle of the BL-IM,the mathematical model of the BL-IM is established.Based on this model,the BL-IM control system of air gap magnetic field orientation control is constructed,which lays a foundation for rotor vibration suppression and sensorless operation.Secondly,to handle the unbalanced vibration caused by the centroid deviation in the BL-IM,a dynamic unbalanced compensation method is proposed.Based on the principle of traditional minimum force suppression,the best compensation value can be quickly searched by combining with coordinate system algorithm.The fundamental frequency signal is extracted from rotor displacement information,and the best compensation signal is calculated by Proportion-Derivative(PD)iterative algorithm.At the same time,the coordinate system search algorithm is combined with PD iterative algorithm to improve the calculation accuracy and speed of unbalanced compensation signal,and then the unbalanced compensation control of the BL-IM is realized.Thirdly,in order to realize the low-cost sensorless operation of the BL-IM in the wide speed range,a rotor sensorless operation control strategy based on hybrid flux observer is proposed.Based on the derivation of the flux calculation equation of the flux observer in different speed region,the switching point of the hybrid flux observer in the medium speed region is analyzed.The switching point of the hybrid flux observer is adjusted based on the speed correlation function to improve the observation performance of the hybrid flux observer.The calculated flux is substituted into the motor flux-displacement equation to realize the sensorless operation control of the motor system.Finally,the BL-IM digital control experimental platform with TMS320F2812 DSP as the control core is constructed,and the hardware and software systems are designed respectively.Based on the BL-IM experimental platform developed by the research group,the experimental research is carried out.The speed response characteristics,current characteristics and suspension characteristics are studied.The results show that the digital control system can not only realize the stable rotation and suspension of BL-IM,but also have good dynamic and static characteristics. |
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