New developments in the diagnosis of faults in line-connected and direct torque controlled induction motors

This paper presents recent developments in the use of a new technique for the diagnosis of faults in three-phase induction motors. The proposed diagnostic technique, which is based on the multiple reference frames theory (MRFT), has been successfully used in the diagnosis of stator faults, rotor faults and air gap eccentricity in line-connected and direct torque controlled (DTC) induction motors. The use of the MRFT represents a step forward towards the unification of the diagnostic process of faults in induction motors and drives by using the same technique to diagnose any type of faults. Due to the modular structure of the MRFT, virtually it can be used to diagnose any motor fault that has a direct impact in one or more supply currents. In addition, as it was demonstrated in a previous work, the technique is particularly adequate for an easy integration into the control system of a DTC induction motor drive at no additional cost.