The Study Of Direct Torque Control Inverter Based On DSP

With the development of modern industry, speed control technology of AC motor has become a research hotspot due to the different needs of motor performance. With the development of power electronic device and the microprocessor with high operation, various frequency control strategies have emerged, among which the vector control and the direct torque control based on the motor mathematical model are more prominent.Direct torque control strategy is based on the stator flux orientation. Compared with vector control, direct torque control need neither the complex calculations about rotating coordinate transformation, nor simplify the mathematical model of the motor. The direct torque control is concise in structure and algorithm, and the torque signals can response timely. Consequently, the real-time performance of the system is improved. The purpose of this paper is to research the direct torque control inverter based on DSP.First, the development of inverter and the current research situation of direct torque control system are described. The thought of direct torque control is analyzed, including the related concepts and the operating principle of various components. Additionally, in order to improve the control performance, the traditional six-sector model is subdivided into twelve-sector model. Meanwhile, considering the limitation of inverters’ switching frequency, a control method has been proposed which can achieve the switching between the round flux and the hexagon flux. Second, many simulation results based on Matlab/Simulink software are presented, and the feasibility of this control system has been verified. Third, the hardware design, including each component modules of the main and control circuit is introduced. The DSP microprocessor is the core of the control circuit, and it completes the whole control method including the detection and processing for the sample signal, and corresponding switching output signals using CCS3.3 software in C language. Finally, through debugging the whole control system, the purpose of speed control is achieved. Each signal waveform in the experiment is given and analyzed.