A contribution to the development of transient models for digital simulation of saturated induction machines with deep bar effect

A model is presented that takes into account saturation in the main field paths, including cross-saturation, as well as nonlinear leakage reactances at heavy currents, and deep bar effect in rotor bars. An equivalent circuit, for a rotor with deep bars that can be adopted to rotor slots of different shapes, is presented. The rotor bars are split in two layers, each of which is represented by several modified π-links. The equivalent rotor circuit has proved to be valid over a wide range of frequencies. Necessary data are provided from catalogues and other fairly open sources. The accuracy of the resulting rotor circuit is calculated according to comparison with direct calculation on a larger motor, and for a smaller motor direct measurements have been carried out in the laboratory. On the model a series of simulations are performed, with different degrees of saturation and deep bar effect, to demonstrate applications of the model in analyzing starting conditions by different starting methods, braking and contribution on short circuiting