The Research Of Speed Sensorless Direct Torque Control System

Direct Torque Control (DTC) becomes a very high performance AC motor control technique after vector control in recent years, which has been widely applied because of its simple structure, robust characteristics and excellent dynamic response. The speed sensorless technique which can simply the hardware structure of the variable speed system and reduce the system cost is a very hotspot of current research works. The combination of these two theories is one of the directions of the development of motor control technique.This thesis thoroughly researches the speed sensorless DTC system in respects of control strategy, platform of controlling system and software design of control system mentioned above, with induction motor as the controlling object, the high quality digital signal processor dsPIC30F6010, made by Microchip corporation, as the kernel of controller, together with the help of basic DTC theory and the approach of speed identification over speed sensorless system. First, the speed estimator and model reference adaptive control which both adapted to the speed sensorless DTC system are proposed on the basis of analyzing the principles of DTC. In order to resolve the problem of torque ripple and inaccurate speed estimate in low speed, a vectors subdivision method based on SVPWM is proposed. Then, the hardware platform of digital AC drive control system based on high performance digital signal processor dsPIC30F6010 and intelligent power module PM30CSJ060 is introduced, then the function of control system are particularly described and the circuit configurations are given; The software design of the two speed identification and the process of control system are introduced, the characteristics of dsPIC30F6010 instruction is shown too. At last, the experiment of speed sensorless DTC is carried out, and then analyzes the experiment results.In the end of this thesis, the problems of present system are pointed out, and useful suggestions are advised.