Abstract :
Electromagnetic field theory is applied to the analysis of performance of an induction-motor rotor when it is exposed to a rotating magnetic field of constant amplitude. An idealized model of the rotor is taken and the analysis is simplified by the application of the concept of wave impedance. The model rotor is capable of simulating the effects of tooth-top and zigzag leakage fluxes, but end effects are neglected. The equations of performance thus obtained are shown to be identical with those obtained by the conventional theory when the latter includes skin effect. The model motor used by Mishkin (Quarterly Journal of Mechanics and Applied Mathematics, 1954, 7, p. 472) is shown to give results widely different from those obtained in practice, since it neglects the zigzag leakage fluxes. The analogy between the tangential force acting on the rotor and radiation pressure is indicated, and it is shown that a change of variable familiar in microwave theory leads to the theory of the variable-speed induction motor developed by Williams and Laithwaite [Proceedings I.E.E., Paper No. 2097 U, June, 1956 (104, A, p. 102)].
