Performance analysis of the sensorless induction motor drive system under faulted conditions

In this paper a performance analysis of the speed sensorless Direct Rotor-Field Control (DRFOC) structure of the induction motor (IM) drive with rotor faults and disturbance in DC-bus voltage conditions is presented. In the sensorless IM drive the rotor flux and speed is reconstructed using the MRAS^CC estimator, where the induction motor is used as a reference model. The stator current estimator and current model of the rotor flux are used as adapted models in this MRAS^CC estimator. The proposed MRAS^CC estimator is very robust to all motor parameter changes hence it should work properly in a faulty rotor. In this paper simulation and experimental results for the sensorless IM drive with broken rotor bars and under the DC-bus voltage oscillations, short brakes and DC-bus over-voltage operation are presented. The low speed region and the dynamic properties of the IM drive under these faults are also tested. The range of stable operation of the control system is shown.