Research On Speed-sensorless Vector Control System Based On Mras For Asynchronous Motor

The research on AC motor speed control system includes the knowledge of many other subjects, such as the power electronic technology, the computer control engineering and the induction motor theory etc. Since the AC motor is a multi-variables and close coupling body, the realization of high performance induction control system becomes a hard work. Vector control theory provides a basic assurance for the high performance induction control. Due to the disadvantages of speed-sensor in vector control, speed-sensorless vector control comes to instead of speed-sensor in case of high precision and high performance. Speed-sensorless vector control system of induction motor is not only an important aspect but also a hotspot of investigation in modern AC drive.In this dissertation, based on analysis the theory of speed-sensorless vector control system, the methods to estimate speed without sensor are discussed, the vector control system using model reference adaptive is simulated. To realize the designed system, necessary hardware and software are also schemed.Firstly, progress of control strategies of alternating current motor and speed-sensorless vector control technology in recent years is summarized, and the advantages and disadvantages of different strategies are enumerated and compared. Then the principles of vector control, coordinate conversion and space vector pulse modulation (SVPWM) are expounded. Mathematical models of asynchronous motor in different coordinates are described. Then speed-sensorless vector control system based on model reference adaptive system (MRAS) is discussed. Based on these, the simulations of speed-sensorless vector control system with model reference adaptive system is realized in MATLAB/Simulink, and the simulation results are discussed. Finally, the software and hardware based on TMS320F2810 to realize speed-sensorless vector control system for asynchronous motor are schemed.The results of the simulation show that the speed-sensorless vector control system for asynchronous motor has a satisfactory identification accuracy and dynamic performance.