The starting of single-phase induction motors having asymmetrical stator windings not in quadrature

Generalized rotating-field concepts, developed in an earlier paper, are used to analyse the behaviour of a single-phase induction motor having asymmetrical stator windings not in quadrature. The analysis includes the effects of the air-gap harmonic fields and is applicable for all values of the turns ratio, k, and the displacement angle, θ. It is shown that the generalized equations of performance reduce to those obtainable by other methods for the few special combinations of k and θ where the latter could be accurately applied. The starting performance of the motor is expressed in terms of dimensionless parameters, and the effect of θ on the starting torque is discussed in some detail. It is shown that though more starting torque is obtained by making θ greater than 90°, the magnitude of the increase depends upon the rotor resistance and the effects of the harmonic fields. Tests on standard machines show good agreement with theoretically predicted performance.