Study And Implementation Of Speed-sensorless Direct Torque Control Strategy Based On DSP

In recent years, the control techniques of AC motor are developped rapidly. The Direct Torque Control (DTC) technique attracts more and more attention after Vector Control theory because of its robust characteristic, simple realization and excellent dynamic response.The advantages of speed-sensorless technique have made it become a focus of current motor control reseach works.As the combination of these two techniques, speed-sensorless DTC system become one of the directions for motor control technique in future.In this paper, Based on the comprehensively deep research on the induction motor's mathematic model, two aspects are studied,which are the improvement of torque control performance and the observation methods of rotor speed about speed-sensorless DTC system.The direct torque control methods and speed-sensorless theory are studied profoundly.It is analylized from flux self-control and torque self-control,which illustrates the superiority of DTC method.Aiming at the methods of rotor speed observation on speed-sensorless DTC system, the paper analyzes different methods and compares them to indicate their advantages and disadvantages. Simulation of the control system is carried out by MATLAB/Simulink. The result of simulation is analyzed .It verifies the feasibility and validity of the speed observation method in this paper. This method has simpler control algorithms and little computational burden and can be easily implemented in digital control system. It can follow the presented rotor speed perfectly and fastly.A speed-sensorless motor DTC system which includes DSP TMS320F2812 as its central control unit is developed. Its main circuit loop adopts IPM to compose the frequency conversion setting. The software flow chart includes central software, initialization, torque control ISR, timer ISR and DSP receiving data flow. It realizes to detect the motor stator's current, to adjust flex and torque, to estimate the rotor speed, to offer PWM driving signal by software based on DSP.