Stator resistance estimation scheme using fuzzy logic system for direct torque controlled induction motor drive

Direct Torque controlled induction motor (DTC-IM) drives have been used widely over last few decades. DTC-IM drives use the stator resistance of the motor for stator flux estimation which directly depends on the stator resistance of IM. Proper estimation of the stator resistance is very important because stator resistance varies due to the increase in temperature of the machine during operation. An online estimation of the stator resistance of the induction motor using model reference adaptive system (MRAS) and fuzzy logic for the direct torque control drive is modeled and verified in this paper. The error between the actual state variable of the machine and the estimated value of the reference model and rate of change of this error is used as input by the fuzzy estimator which gives the change in resistance value as output. From simulation it has been proved that the estimator can track the stator resistance value within 70 ms when a step change of stator resistance has been applied. The efficacy of the estimator is investigated in simulation by varying the stator resistance from the nominal value which has been done in MATLAB/SIMULINK.