Theory and performance of solid - rotor induction and hysteresis machines

A general theory is described for the evaluation of hysteresis and induction torques in rotating machines with unlaminated unslotted rotors using the concept of nonlinear complex permeability. Typical generalised characteristics derived for machines with either solid or tubular rotors show the influence of curvature and saturation on the normalised rotor impedance. Good agreement was obtained between measured and theoretical performance values over wide ranges of machine operation with either constant-voltage or constant-current energisation. However, significant errors were evident in the theoretical pull-out torque characteristics of hysteresis machines; an empirical method of including the effect of rotational hysteresis was found to improve the accuracy of representation.