Reduced-order representation of the deep-rotor-bar phenomena in induction machines

To accurately model the deep-rotor-bar phenomena in squirrel-cage induction machines for a wide range of frequencies, the distributed rotor may be generally represented as a high-order transfer function or an equivalent lumped-parameter ladder network. However, when lower-frequency electromechanical transients are of interest, an effective reduced-order model, in which a single-branch rotor resistance is changed as a function of rotor speed, can take these effects into account without increasing the model complexity and order. In this paper, the reduced- and high-order formulations are compared with the classic models and experimental results. It is found that the proposed reduced-order model provides very good accuracy for predicting low-frequency dynamics. This model can be particularly useful for studying larger systems composed of a number of electromechanical subsystems.