Analysis of Induction Motors with Asymmetric Windings

Abstract

The rotating coupled circuit equations and the corresponding equivalent circuits are developed for single-and poly-phase induction motors. For our general analysis purposes, a three-phase induction motor is considered with its primary windings at arbitrary locations. Each phase of a three-phase motor is represented by an equivalent circuit not only to allow for uneven direct transformer interactions among the fluxes but also to account for different number of conductors, wire size, winding factor, etc., each phase may have. The special case of a balanced three-phase induction motor is also considered. The analysis is then applied to single-phase induction motors with both quadrature and nonquadrature winding-displacements. The most useful feature of the present development is that it helps create a unified computer-aided analysis procedure for almost all types of induction motors. The accuracy of the theoretical development has been verified by conducting tests on both single-and three-phase induction motors. Though the comparisons are made on fractional horsepower motors, the types being built at Universal Electric, the author is certain that the general theoretical approach suggested here is equally applicable to all sizes of induction motors.