A new observer for speed and rotor time constant estimation of an induction machine in vector control method

In this paper, the effect of rotor time constant variation on the dynamic performance of rotor flux in the speed sensorless indirect Field Oriented Control (FOC) method of induction motor is considered, then a novel method for adaptation of rotor time constant based on Model Reference Adaptive System (MRAS) is presented. The computer simulations have shown the validity and the feasibility of the proposed method that possesses the advantages of MRAS implementation; the high speed of processing. In addition this method is more adapted for practical implementation because it uses the stator voltages and currents in the estimation of the rotor time constant and speed. Also, the method is suitable for implementation with conventional sensorless FOC drives.