Research On Speed Sensorless Control System Of Asynchronous Motor Based On Sliding Mode Variable Structure

AC asynchronous motor is indispensable in industrial production and daily life,and the wide application makes it necessary to analyze the structure and control of the motor.In the research,the nonlinear,multi-variable and other characteristics of the motor make it difficult to control.In order to satisfy all kinds of high performance AC drive,many nonlinear control methods have been using in this field in recent years,Sliding Mode Control(SMC)has been drawn great attention among many experts and scholars because it has strong robustness and ability to recover from disturbance.In this paper,the method that applies sliding mode variable structure technology to vector control system and combines sliding mode variable structure technology with Model Reference Adaptive System(MRAS)widely studied in recent year can play the advantages of both methods to achieve the desired control.The specific research contents are as follows:(1)The different kinds of identification methods of speed sensorless observer are summarized,and the basic principle of asynchronous motor vector control are summarized,and further studies its characteristics,which provides an important theoretical basis for the later research.(2)The principle and key problems of SMC are analyzed.In view of the defects of conventional PID or PI speed adjuster,the tendency rate algorithm is used as the optimization method to design a kind of sliding mode variable structure speed regulator in asynchronous motor vector control technology by improving the algorithm formula of the traditional uniform velocity tendency rate.(3)Several speed identification observer of variable structure MRAS are designed,improves the phenomenon of the general buffeting appearing in the sliding mode variable structure system and weakens this drawback.In addition,it designs the double sliding mode variable structure MRAS speed observer to further improve the performance of the system,and compares the improvement of the results with the traditional sliding mode variable structure speed identification system to verify its speed identification performance and its advantages and disadvantages.The results show that the proposed sliding mode variable structure MRAS velocity observer has good dynamic performance.(4)The vector control system based on TI's TMS320F2812 DSP and PS21265-AP IPM is designed to realize the vector control system of asynchronous motor in hardware.