General theory of solid-rotor induction machines

A general theory of the torque/slip and current/slip characteristics of solid-rotor induction machines is developed in terms of dimensionless coefficients, and its validity is demonstrated by measurements on machines in the range 6¿1500 W. Generalised characteristics are presented in the form of curves of the dimensionless coefficients. The analysis is based on an expression for equivalent rotor impedance which is inversely proportional to the product of airgap flux and slip and which has a constant phase angle. Various methods of calculating eddy-current losses in solid rotors give impedances of this form, and the use of some of these in the generalised analysis is assessed.