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T. Wolbank, R. Wöhrnschimmel:
"Transient electrical current response evaluation in order to detect stator winding interturn faults of inverter fed ac drives";
Talk: IEEE International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives SD, Gorizia, Italy; 2001-09-01 - 2001-09-03; in: "Proceedings", (2001), ISBN: 88-900645-0-1; 549 - 554.

Abstract--In inverter fed drives the voltage stress of the isolation often leads to stator winding interturn short circuits. These faults have to be detected on-line and in an early stage in order to prevent further damage in adjacent coils and the power electronic devices. In this contribution a new method to detect asymmetries in inverter fed drives is presented. These asymmetries may either be caused by a stator winding isolation fault or by rotor eccentricity. The proposed method uses the reaction of the machine to a transient excitation caused by the switching of the inverter. This transient excitation may be realized by separate voltage test pulses or it may be integrated in the PWM scheme. The exploitation of the transient current response can be used to detect and locate asymmetries in electric machines. Due to the high reachable accuracy of the method even asymmetries caused by slotting and saturation are detectable. Only the sensors and control electronic already available in modern inverter fed drives are used, thus no additional sensors are necessary to apply the method.
The method is independent from machine parameters and applicable in steady state as well as transient operation of the drive.
Measurement as well as simulation results are given which verify the applicability of the proposed method.