Temporal envelope detection by the square root of the three-phase currents for IM rotor fault diagnosis

This paper deals with a reliable and effective method for induction machine rotor fault diagnosis, using three-phase stator currents. Through a theoretical demonstration based on the magnetic field approach, it has been shown that broken rotor bars produce amplitude modulation in the stator current which can be extracted with very low complexity by calculating the root of the squared three-phase stator currents. The theoretical background of the proposed method is presented then experimentally confirmed by using three currents measured from a test bench that contains three motors, one healthy and two other with broken bars. Each motor is subjected to two load conditions (low and high). The obtained results show the robustness and effectiveness of the proposed technique, even at low-load conditions, comparing to the classical MCSA method.