The Research For Improving The Low Speed Performance In DTC System Of Speed-sensorless

After direct torque control(DTC) technology was invented,it has been given wide concern and has got rapid development because of its original control notion,concise system structure and excellent static and dynamic characteristics.Asynchronous motor DTC has the characteristics of control algorithm easy,dynamic response fast and so on.It is a high performance induction motor control method after vector control.Speed sensor in DTC system is the basic assurance which to achieve high precision speed closed loop control,but it always increases the system cost and decreases the system reliability.In addition,speed sensor is not allowed to use in many occasions.Therefore, speed sensor-less technology gets widespread attention.This paper introduces the basics theory and the principle of direct torque control system.According to the principle,simulation model of direct torque control system with chaos optimizes BP neural network speed identifier is built.By the use of the properties of ergodicity,randomness and regularity of chaos,combining global rough search and local elaborate search of chaos variable,optimizing weight value and threshold value of BP neural network,getting the global optimization values of neural network.Seen from simulation results that DTC system with chaos optimizes BP neural network speed identifier has high approximation precision and good generalization capability, speed-sensorless DTC system is carried out.In the time of low rotor speed,DTC system is liable to be affected by the change of stator resistance,torque pulse is big and so on.Due to this disadvantage,DTC system of approximate round flux is built based on DTC system of traditional hexagon flux,and analyzed the results of the simulation.Based on the theory analysis and simulated research of DTC system,this paper has realized soft program at the pain of TMS320F240 DSP setting.From the spot debugging result of motor control using intelligence observe and control comprehensive test-bed,it is observed that the design plan of this paper is good practice and efficient.