Research On Bearingless Induction Motor And Its Sensorless Control

In recent years,with the rapid development of industry,the conventional motors have been difficult to fulfil the requirements of special electric drive / drive system.Through the two sets of winding to change the air gap magnetic field distribution,so that the rotor at the same time to achieve suspension and rotation of the bearingless motor,changing the way the ordinary motor rotor support,thus avoiding the mechanical friction?wear? short bearing life and other shortcomings,becoming one of the key research directions in the field of high speed motor.Bearingless Induction Motor(BIM)integrates the advantages of magnetic bearings and conventional induction motors,so it is in the field of medical equipment,sterile?non-polluting food processing areas?high-speed high-precision aerospace fields have potential application values.Under the support of the Natural Science Foundation of China(51475214)and the Natural Science Foundation of Jiangsu Province(BK20141301),based on the analysis of the operating mechanism and mathematical model of BIM,the paper focuses on the research of BIM speed sensorless and displacement sensorless control technology,the Specific contents are as follows:Firstly,we introduced the research status at home and abroad and application fields of bearingless motors,On this basis,the development direction of BIM is discussed.Then,the mathematical model of BIM is derived,and the BIM vector system based on air gap magnetic field is constructed.Secondly,Aiming at the shortage of mechanical sensors in BIM operation,a new control strategy for rotor speed self-detection based on low frequency current injection method and a new control strategy for rotor radial displacement self-detection based on improved voltage model are proposed.The former uses the injected low frequency current to obtain the rotor position deviation angle,which is adjusted further through the PI(proportion integration)controller,and then the rotational speed of the motor's air gap magnetic field is obtained,then the rotor speed is estimated.The latter is based on the voltage model method,using low-pass filter instead of pure integrator of the voltage model,and then using the relationship between inductance matrix and rotor radial displacement,rotor displacement estimator is designed,so as to achieve the purpose of accurate identification of radial displacement.Using the above two sensorless control methods,the simulation model of the sensorless vector control system of bearingless induction motor is built,and the simulation research is carried out.The simulation results show that the proposed method can quickly detect the rotor speed and rotor displacement,and has excellent dynamic and static performance.Finally,The hardware circuit and software program of BIM vector control system are designed.The hardware circuit includes the speed sensorless interface circuit,displacement sensorless interface circuit and power circuit etal,the software program mainly includes the main program and the interrupt service routine.Then the experimental platform of BIM sensorless vector control system Based on the TMS320F2812 DSP chip is built and the experiment is carried out.The experimental results show that the proposed methods can quickly and accurately detect the rotor speed and rotor displacement,to achieve the desired results.