Improving the performance of speed sensorless induction motor drive with rotor broken bar failure by stator current signature analysis

This paper proposes a new method to improvethe performance of indirect vector controlled speed sensorlessinduction motor (IM) drive under rotor bar fault. When a rotor bar fault occurs, the parameter of the system is altered. This creates a mismatch between estimated speed and actual speed of the drive. The difference magnifies with load and with more number of rotor bar failures. As the drive is speed-sensor free, there is no direct way to find the deviation in speed. However, indirect estimation is possible through sensing the stator currents. Occurrence of rotor bar fault produces oscillating component in the torque-producing-component of stator current. Frequency of this oscillation is estimated using the proposed method and is used to calculate the actual rotor speed.This results in improvement of the drive performance.A newly proposed X-MRAS based speed sensorless algorithm is used. However, the proposed algorithm can also be used for other existing speed sensorless drive. The proposed approach is simulated in MATLAB/Simulink and experimentally validated through a dSPACE-1104 based laboratory prototype.