Speed Sensorless Direct Torque Control System of Induction Motor Based on MRAS and FNN

Due to the large pulsation of torque and flux in traditional direct torque control system,the anticipated voltage vector modulation technique was used based on FNN control.Speed sensor was inconvenient and expensive and the flux observer heavily depended on resistance,especially in low speed.Thus,a speed, resistance and flux adaptive observer was designed based on model reference adaptive control theory.The stator currents and stator fluxes were used as state variables,while the rotor speed and the rotor resistance law were defined by Popov hyperstability theory.The speed sensorless direct torque control system was established under Matlab/Simulink.The results showed that the fluctuation of the torque and flux was smaller and the stator flux and the rotor speed were observed more exactly.