Lecture Notes in Electrical Engineering
The paper describes machine model-based speed observers for speed sensorless induction motor drive with direct torque and flux control. However, the wrong information of machine model, especially stator resistance, affects the performance of the direct torque control. Thus, model reference adaptive system based scheme is developed for adapting stator resistance. At first, the sensorless control structures of the induction motor drive are implemented in MatlabSimulink environment. Then, comparison is done by evaluation of the rotor speed difference. The simulation results confirm that model reference adaptive system speed observers and adaptation technique in control structures are simple to simulate and experiment. By comparison of speed estimators without and with adaptation technique, current based model reference adaptive system observer and Luenberger observer give higher accuracies of the speed estimation, more robust with uncertainty of stator resistance.