Diagnosis of rotor faults in traction drives for railway applications

This paper presents the virtual current technique as a new model-based diagnostic procedure for the diagnosis of rotor faults in traction drives for railway applications. The occurrence of a rotor fault in a traction drive based on induction motors introduces some oscillations at twice the slip frequency in the rotor flux as well as in the magnetizing current component. By measuring the amplitude of these oscillations and after an adequate processing of this information, using some motor and controller parameters, one can reconstruct a virtual magnetizing current component which, after adequate normalization, can be used to detect and quantify the extension of rotor faults in a drive subjected to a direct rotor field oriented control scheme. The simulation and experimental results shown demonstrate that with this diagnostic technique, it is possible to diagnose effectively rotor faults, independently of the drive operating conditions, both in steady-state and transient regime.