Low-speed performance of the stator current-based MRAS estimator with FL controller in the sensorless induction motor drive

In the paper the dynamical performance and sensitivity to the motor parameter changes of the sensorless induction motor drive with MRAS type speed and flux estimator is demonstrated. The stability analysis of the stator current-based MRAS^CC estimator of the induction motor is presented. The influence of equivalent circuit parameter changes of the induction motor as well as coefficients of the adaptation algorithm of the MRAS^CC estimator to the pole placement of the estimator transfer function and stability of the whole drive system is analysed and tested. The classical PI controller in speed adaptation algorithm of the MRAS^CC estimator is changed by the nonlinear, fuzzy logic controller, resulting in the MRAS^CCFL. The allowable range of motor parameter changes, which guarantees the stable operation of the sensorless field oriented drive system with this MRAS^CCFL estimator is determined and compared with the MRAS^CC solution.