Research On Sensorless Control Of Permanent Magnet Synchronous Motor

Because of small size,simple structure and strong reliability,permanent magnet synchronous motor is widely used in various speed-adjustable industrial systems,such as electric vehicles,compressors,and so on.The precise information of the position and speed usually detected by sensors.On the condition of poorly detection environments,the sensor is susceptible to corrosion and interference,which affects the normal operation of the equipment seriously.And even cause major personal safety accidents in serious cases.Due to increase the detection accuracy and stable operation of the motor,and reduce the system cost.The permanent magnet synchronous motor is taken as the research object.And the high-order extended state observer and non-singular terminal sliding mode control based on novel adaptive reaching law is proposed.The structure of this thesis is as follows.Firstly,the vector control technology is introduced,and the mathematical model of the motor system is established in the meanwhile.The speed regulation method of permanent magnet synchronous motor based on vector control is studied.These works provide conditions for the develop of observer and controller in the following parts.Secondly,to solve the problem of poor dynamic response and poor robustness of traditional state observer,a high-order extended state observer is proposed.Extend a second-order disturbed system into a high-order linear system,take the unknown back electromotive force as a new state.And the high-order linear system is expanded by adding expanded state variables to form a high-order expanded state observer.The designed sensorless control method is verified by simulations.And the simulation analysis concludes that compared with the ordinary state observer,the proposed control method can achieve the goal of suppressing chattering.Then,in order to solve the problem of tracking error of the sliding mode surface cannot converge to zero within a limited time,and the chattering in sliding mode control.An novel sliding mode controller is developed to reduce the speed fluctuation.The traditional sliding mode surface is improved by using the nonsingular terminal sliding mode control theory.The system state variable and amplitude gain are introduced into the traditional constant velocity reaching law.So that the reaching law can be expressed as two different reaching forms.It ensures the system state reaches the switching surface gently.The improved speed controller is verified by simulations.And the simulation analysis concludes that compared with the PI controller,the proposed control method can improve the dynamic response speed of the speed regulation system.The chattering is suppressed with the cooperation of the high-order extended state observer in the meanwhile.Finally,the relevant experimental tests of the control method are carried out on the 750 w motor control system.The module is designed according to the schematic diagram.The proposed improved state observer and the novel speed controller are verified by a number of experiments.By analyzing the experimental graph,we can get that the improved state observer can efficiently detect the values of rotor position.And the improved speed controller can improve the operation ability of the motor and suppressing chattering in the meanwhile.