Analysis of the asymmetrical operation of dual three-phase induction machines

The paper deals with the problem of the unbalanced current and power sharing in the dual three-phase induction machine supplied by a sinusoidal voltage source. In particular, the case discussed has two three-phase sets of full-pitch windings, spatially shifted by 30 electrical degrees with isolated neutrals. The unbalanced current sharing between the two winding sets is due to the not eliminable small system asymmetries. First, the machine model to compute the unbalances is presented; second, the analysis of the system asymmetries and their effects on the machine operation is discussed. Simulated and experimentally tested sinusoidal supply conditions are presented for a 10 kW dual-three phase induction machine prototype.