Tracking Control Of Position Sensorless Permanent Magnet Synchronous Motor

The permanent magnet synchronous motor(PMSM) plays an important role in modern industrial applications such as rail transits, medical equipment and aerospace, owing to their good performance provided by their simple structure, high efficiency, high power density and high torque to inertia ratio. In the high-performance control of the PMSM system, the PMSM rotor position and speed are essential feedback. The traditional solution is to adopt mechanical sensors(such as rotating transformer, photoelectric encoder) to detect the rotor position and speed information. However, the use of sensors has not only increased the system cost, increase the volume of the motor, but also reduce the system reliability and durability. Then it restricts the PMSM application in some special occasions.As the maturity and perfection of the modern control theory, the traditional mechanical sensors are abandoned in the sensorless control, and it got the further research of scholars. Through the adoption of a certain estimation method to obtain the rotor position and speed information, which can realize the high performance control of the PMSM. Therefore, the sensorless control technology of the PMSM has become an important research direction. This paper researching and analyzing the high performance control of the PMSM without sensors based on the sliding mode observer method. This paper mainly revolves around the following:First of all, the paper combining with the domestic and foreign research present situation, the methods of the commonly sensorless control technology are analyzed. By comparing the advantages and disadvantages, the method of sliding mode observer which is easy to implement is chose.Secondly, in the thesis, the three different kinds of coordinate system are studied and the PMSM mathematical model is built under the different coordinate system. Further study the theory of the vector control and sliding mode variable structure control. In view of the chattering phenomenon of the PMSM system, in this paper, the switching functions using a continuous function. At the same time, this paper constructs the back EMF observer instead of low pass filter to eliminate the phase delay problems brought by the low pass filter. And the sliding mode observer design steps are given. The validity of the design method is verified by simulation.Thirdly, through the study of the terminal sliding mode and nonsingular terminal sliding mode, and the paper analyzes the advantages and disadvantages of them. The terminal sliding mode control exist the problem of chattering and slow convergence, however, the singular terminal sliding mode will not appear this problem. According to the mathematical model of the PMSM, the nonsingular terminal sliding mode is combined with a new reaching law, and then a new observer is designed, in this paper. Its stability is verified by theoretical analysis and simulation.Finally, the main work of whole thesis is summarized. We analyze the deficiency of sensor control in current application, and the future research direction is proposed.