Based On Back Emf For Speed Sensorless Vector Control System

With the help of the Vector Control, speed and torque performance of AC Drive System can be comparable with DC speed control system, and the rapid development of power electronic technology accelerates the development pace of AC speed system. Speed sensorless control technology overcomes the inconveniences brought by the sensor, expands the application scope of AC speed control system, reduces the costs of system, and becomes the research hotspot in recent years.In this paper, first, the principle of Vector control, the transformation matrix and the basic equations of asynchronous motor are discussed, the mathematical modesl of asynchronous motor in different reference frames are derived, and the decoupling of asynchronous motor torque current and excitation current is realized; Second, the principle, advantages and disadvantages of various speed sensorless control methods are analyzed and compared; Then a more detailed comparison of theory and simulations are carried out between the Back Electro Motive Force and Model Reference System used commonly; Last, a fuzzy controller to detect the stator resistance on-line is designed in order to enhance the robustness of vector control system.Using MATLAB/SIMULINK software, simulations of vector controler, speed estimator, stator resistance estimator and the entire system are realized by establishing models and programming to verify the feasibility of these methods. Simulation results prove that such design has good dynamic and static performance.