Research And System Development Of Direct Torque Control Of Asynchronous Motor

Following the Vector Control(VC) technique, Direct Torque Control (DTC) of asynchronous motor, which has been developed rapidly in the recent decades, is a new and high-powered AC driving control technique. The idea of DTC is novel, the structure is simple, and the control method of DTC is direct. DTC is an excellent AC driving control technique, which has high static and dynamic performance and has been successfully applied in many occasions up to now.The mathematical model of asynchronous motor is researched thoroughly in this paper. On the basis of the study of the traditional DTC, a new stator flux and torque controller is proposed, and the traditional voltage vector selection table is replaced by a new selection table. Speed sensorless AC driving control technique is an important trend of modem AC drives now, because the system with speed sensor costs more and the reliability is weakened. This thesis has discussed several primary algorithm of speed estimation, constructed an adaptive stator flux observer and emphasized on the algoritlim of speed estimation based on the adaptive stator flux observer. In order to demonstrate the feasibility of the asynchronous motor's DTC system, a complicated simulation control system of DTC is designed based on MATLAB; Moreover, the characteristics of the DTC and the existing problems are analyzed in detail.In addition, DSP (TMS320LF2407A) of TI Corporation is used as the core-processing chip of the digital control system, and Intelligent Power Module (IPM) is used as the power switch component. The hardware structure of the system is developed based on DSP and IPM, and the software design is based on DSP compiling language, the experiment of DTC system is earned out.The results of the simulation and experiment show that the control methods described in this thesis can achieve good control performance. Because the high-integrated components are used, the hardware structure of the system has been greatly simplified, the anti-jamming performance and the reliability of the system has been improved.