Induction motor parameters in case of rotor electrical asymmetry

The paper presents estimation of parameters alternation in a three-phase induction motor due to broken rotor bars, which cause electric and magnetic asymmetry in the machine. Using d-q model of induction motor this asymmetry is reflected as pseudo-saliency through different resistances and inductances in both axes. An extensive study has been performed to simulate various cases of faulty cage, which cannot be achieved by measurements on actual industrial drives. Simulation results can be efficiently used for analysis of closed-loop induction motor drives, in which determination of rotor faults, due to the intrinsic speed correction performed by the controller, is much harder to achieve.