Estimation of Induction Motor’s Rotor Time Constants for Diagnostic Purposes

This paper presents an upgrade to the dynamic model of an induction motor in rotor reference frame that allows independent modifications of rotor time constants in each axis. Thus, modelling of different scenarios of rotor faults at different ambient temperatures becomes possible through variations of time constants. If applied to an observer, the model could be used as a tool for determining the rotor time constants in both the healthy and faulty rotor. In the former case, constants in both coordinates are equal, yet temperature dependent. In case of the fault, the constants differ. This normalized difference is a fault indicator related to the severity of the fault. Different scenarios and challenges are presented and analysed through simulations.