Equivalent Circuits for Single-Phase Squirrel-Cage Induction Machines with both Odd and Even Order MMF Harmonics

The special winding connections used in certain dual voltage or multiple-speed single-phase induction motors lead to large, even order MMF harmonics. The calculation procedures used to evaluate machines of this type must include proper representation of these harmonics. This paper develops the general describing equations for a two-phase machine with arbitrary MMF distributions. These equations are then specialized to yield harmonic equivalent circuits for steady-state operation. Proper interconnection of these harmonic circuits yields equivalent circuits representing actual machine windings. Examples are given, including circuits for representation of consequent pole windings. A numerical example of a machine operating with only its north poles excited is also included.