Rotor Fault Analysis in the Sensorless Field Oriented Controlled Induction Motor Drive

Abstract

In the paper an analysis of the Direct Field Control of induction motor drive with broken rotor bars is presented. A drive system with and without a mechanical speed sensor is analyzed. In the sensorless induction motor (IM) drive the rotor flux and speed is reconstructed with the use of a MRASCC 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. Most of the speed estimators used in sensorless drives are sensitive to motor parameter changes, especially to the rotor resistance changes. The proposed MRASCC estimator is very robust to all motor parameter changes, hence it should work properly in a faulty rotor. In the paper simulation and experimental results of the sensorless IM drive with broken rotor bars are presented. Characteristic frequency harmonics of the IM state variables connected with the broken rotor bars are introduced. The low speed region and the dynamic properties of the IM drive with rotor faults are tested. The range of stable work of the control system is shown.