Analysis of split-phase electric machines with unequally-loaded stator windings and distorted phase currents

Split-phase machines are multi-phase machines whose stator phases are split into two or more three-phase windings. When all windings are equally loaded, the split-phase topology produces a better air-gap field than the usual three-phase one, with beneficial effects on rotor additional losses and torque quality. This does not occur when the windings are differently loaded, as typically occurs is split-phase motors with one or more out-of-service supplying inverters. This paper presents an analytical approach to accurately predict the air-gap field distortion in split-phase mechines with unequally-loaded windings and in presence of possible phase current distortion. Results obtained with the proposed method are assessed by comparison with FE simulations.