Research On Direct Torque Control System Of Asynchronous Motor Based On DSP

With the power electronic technology and the rapid development of all kinds of motor control technology, Direct Torque Control technology received widespread attention due to its simple thought, fast dynamic response and the advantages of the small effect from motor parameters,and therefore starting from the actual application,researching on the direct torque control system of the asynchronous motor based on digital signal processor(DSP) as the core device has important practical significance.Firstly, this paper analyzes the mathematical model of the asynchronous motor, and expounds the basic principle of direct torque control and introduces the hexagon flux control and circular flux control strategies of the traditional method on the basis of the analysis,summarizes the advantages and disadvantages of the traditional direct torque control, aiming at the deficiency of the traditional method, this paper introduces one method based on space vector pulse width modulation of the direct torque control(SVM-DTC) and its concrete realization method, SVM-DTC adopts PI controller to replace the hysteresis comparator of the traditional direct torque control, using space vector pulse width modulation technology replaces the traditional voltage vector selection table, making the motor flux trajectory approach circular by means of each time and sequence of voltage space vector control,secondly, according to the principle of the traditional direct torque control and SVM-DTC,under the Matlab/Simulink environment, building the traditional direct torque control and SVM-DTC two methods for the simulation modeling, the simulation results show that the SVM-DTC compared with the traditional method can effectively reduce torque ripple and the flux pulsation of the control system, at the same time to ensure the switching frequency constant.Finally, on the basis of theoretical analysis, this paper accomplishes the direct torque control system hardware circuit design with DSP as main control chip, including main circuit,driving isolating circuit, detecting dircuit and protection circuit,etc, and software design of control algorithm, the performance of the control systems design was testes and analyzed, theresults show that the control system can realize the SVM-DTC speed control system, the experimental results and the analysis of the problems in the experiment laid a good foundation for follow-up study direct torque control based on SVPWM method of asynchronous motor.