Sensorless Control System Of Permanent Magnet Synchronous Motor Based On Improved Sliding Mode Observer

Permanent magnet synchronous motor not only has simple structure and high reliability,but also has the advantages of high efficiency and high power factor.Compared with induction motor,permanent magnet synchronous motor has better speed regulation performance.Therefore,permanent magnet synchronous motor is frequently used in a variety of speed regulation occasions and control conditions.Permanent magnet synchronous motor usually rely on mechanical sensors installed on the rotating shaft to obtain rotor position information and speed information.Mechanical sensors not only make the motor structure more complex,but also vulnerable to the interference of the external environment.Therefore,using sensorless technology to replace mechanical sensors has become a research hotspot in the field of motor control.Based on the structure and working principle of permanent magnet synchronous motor,the mathematical model of permanent magnet synchronous motor is established in this thesis.According to the law of coordinate transformation,the mathematical model of permanent magnet synchronous motor is extended to different coordinate systems.Vector control based on is selected as the main control method of sensorless control system of permanent magnet synchronous motor.Combined with the principle of sliding mode variable structure control and the mathematical model in two-phase static coordinate system,a sliding mode observer is constructed to estimate the rotor position and speed of the motor,so as to realize the sensorless technology.Aiming at the problem that the traditional sliding mode observer is prone to high-frequency chattering,an improved scheme combining the continuous switching control function with the exponential reaching law is adopted to reduce the chattering.In order to extract the required rotor position information more accurately,the improved sliding mode observer is introduced into the phase-locked loop algorithm,the modeling and simulation analysis of the control system are carried out in MATLAB.The improved sliding mode observer method is compared with other improved sliding mode observer methods to verify the accuracy of the proposed method.Finally,this thesis selects TMS320F28335 chip as the core device of the control board,and designs the relevant hardware circuits based on the motor control board and power drive board.The experimental platform of permanent magnet synchronous motor improved sliding mode observer sensorless control system is built.According to the vector control theory and the improved sliding mode observer theory,the software algorithm program for realizing the sensorless control system is compiled.According to the simulation and experimental results,it can be concluded that the improved sliding mode observer proposed in this thesis can reduce the chattering of the traditional sliding mode observer,make the prediction results closer to the actual results and have less error.It can meet the requirements of actual motor control system.