Development and industrial application of a practical model for simulation of saturated deep bar induction machines

For the analysis of many operational problems associated with starting, load changes, generating operation and braking, as well as internal and external faults, the application of the simulation technique in many cases appears to be a fairly accurate and practical method. This report deals with the development of a practical simulation model that takes into account saturation in the main flux path and the leakage flux path with high current values, as well as the deep bar effect in the rotor. The suggested equivalent rotor circuit is developed for a deep bar rotor, but will apply to other bar shapes as well, after minor adjustment. A fairly simple procedure for determination of the elements in the rotor circuit based on available data for the motor, is developed. 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. The equivalent rotor circuit has proved to be valid over a wide range of frequency, particularly of importance for inverter operation. The present paper also demonstrates examples of industrial applications of the model in analyzing faults and operational problems