Research On Variable Frequency Speed Control Platform Based On Direct Torque Control Technology

Nowadays,with the rapid development of industrial technology,asynchronous motor is becoming increasingly important.As an effective speed control technology,AC vaviable frequency speed technology has been devoted a great deal of research.Direct torque control technology is an excellent AC drive technique.With the characteristics of simple structure,less parameters and strong robustness,such technique has been used in industrial and agricultural production.This paper decribes the present situation and development of AC speed regulation technology,especially the current technique condition and advancement of direct torque control.Based on the analysis of asynchronous motor and inverter mathematical model,the base princple of direct torque control is introduced in this paper.A MATLAB model is also simulated for the traditional direct torque control system based on circular flux trajectory.In traditional direct torque control scheme,the inverter switching frequency is variable and the motor torque ripple can be large.To solve the above problems,the paper introduces two improved schemes and compared with the traditional system through simulation by using MATLAB/Simulink.The results show that improved systems could overcome the inherent shortcomings in conventional DTC system by reducing the torque and stator flux ripple effectively.At the end of this paper,an asynchronous motor speed control hardware platform based on DSP is designed.The software program based on direct torque control strategy is described and the experiment result is also analysed.