Research And Implementation Of Asynchronous Motor Direct Torque Control System Based On DSP28335

Asynchronous motor (Induction motor) has been widely applied in industry, agriculture, national defense and other fields because of its simple structure, easy manufacture, low cost, reliability and durability and so on. Therefore, it is very important to research asynchronous motor and its control technology.On the basis of reading relevant literature at home and abroad, three-phase asynchronous motor is made as research object and the development of induction motor control is described in the paper. Three-level SVPWM technology is described and improved DTC is researched because of its shortages.Firstly, in view of the lack of traditional two-level inverter such as too large switching voltage, too high dv/dt and so on, this paper researches three-level inverter and its SVPWM technology. Simulation results show that three-level SVPWM method has many advantages such as more switch than two-level inverter, switch tube bearing voltage reduction, smaller dv/dt in switching the switch state and so on. These advantages make three-level inverter own broad prospect of application in induction motor control area.Secondly, this paper analyzes the traditional induction motor DTC theory. Because of the shortcomings for its control method, improved DTC control scheme based on PI controller and three-level SVPWM is researched. This program uses PI controller, SVPWM unit, three-level inverter to replace stator flux and torque controllers, switch state selection and two-level inverter. Simulation results show that this program can reduce the torque ripple, the switching losses and the current harmonic content.Finally, this paper takes high-performance floating-point microcontrollers F28335as control circuit core to establish induction motor control hardware experimental platform. On the basis of this hardware platform, SVPWM is applied to fulfill asynchronous motor control in algorithm and software. Then the detecting results of experiments were analyzed to verify the correctness of the control system.