Simulation Research of Direct Torque Control System with Speed-sensorless

In direct torque control system, stator flux can not be accurately observed at low speed if traditional pure integrator (U-I model) is taken as a flux observer, and using speed sensors to measure rotor speed will increase complexity,cost and maintenance requirements and reduce reliability and robustness of the system. In the paper, a method was put forward that traditional pure integrator is replaced by a closed-loop flux observer to observe the stator flux and speed observer is built to estimate rotor speed based on model referenced adaptive system(MRAS). A simulation model of direct torque control system with speed-sensorless for asynchronous motor was estiblished in Matlab with the method, and the simulation result showed rationality and effectiveness of the method.