Induction Motor Direct Torque Control

With the development of electric and electron technique, various methods and technique were used on motor control these years. One of them, as a new asynchronous motor control technique ,the Direct Torque Control (DTC) technique attracts more and more attention after Space Vector Control technique because of its robust characteristics, simple realization and excellent dynamic response.This thesis introduces the basic principle of direct torque control on asynchronous motor. Through mathematics model of asynchronous motor, stator flux and torque can be got. After the analysis of the state of converter switches, the voltage space vector is received. On the basis of hexagon stator flux trace method of traditional direct torque control, by changing the regulation of stator flux, hexagon and approximate round trace of stator flux can be got when using different voltage space vector. The fast regulation is realized when three-value regulator is used to adjust torque. In order to verify the control method, author designed an asynchronous motor control system using the method of direct torque control. Hardware design uses high-speed digital signal processor TMS320LF2407A as the key control part. Software design adopts hexagon stator flux scheme and round stator flux scheme respectively.After the system is set up, the direct torque control method is realized for a 0.12kW winding asynchronous motor. The experimental result verified the feasibility and exactness of the control method. At the same time the conclusion is drawn that the experimental result of round stator flux scheme is more satisfactory than that of hexagon stator flux scheme.