Sensorless vector control system of induction motor by nonlinear full-order observer

A novel design of a nonlinear full-order observer for sensorless vector controlled induction motors is proposed in this paper. It is known that the speed-sensorless vector control drive system of induction motors does not perform satisfactorily at the low speed, which is caused by the voltage model and its emf calculation of motors. The nonlinear full-order observer system abandons the voltage model and its emf calculation of motors, makes use of the motor as a reference model and the stator model together with the current model as an adjustable model. In this paper, the model reference adaptive system (MRAS) is proposed, and then the nonlinear full-order observer system is presented based on the MRAS. Finally, several simulations verify feasibility of the proposed strategy.