Analysis and Application of Two-Layer Unconventional Windings for PM-Assisted Synchronous Reluctance Motors

This paper presents a new winding configuration theory of conventional and unconventional slot-pole combinations that can be used to configure windings with any slot-pole combination. First, various two-layer windings can be divided into conventional balanced winding (CBW), unbalanced winding (UBW), unconventional even slot winding (UESW) and unconventional odd slot winding (UOSW). In addition, the winding configuration can be divided into two steps-slot sorting and slot distributions to phases-and the rule of winding distribution and connection of the four kinds of windings is given. Moreover, there are four models established corresponding to the four kinds of windings. The air-gap flux density and harmonic of models with double layer flux-barrier PM-assisted rotor and without flux-barrier rotor are analyzed and compared using two-dimensional transient finite element analysis (FEA). The effect of stator magneto motive force (MMF) on torque performance affected by winding configuration is analyzed by comparing air gap magnetic density under two kinds of rotors. The simulation of torque shows that UBW, UESW, and UOSW have a certain reducing effect on torque ripple in PMASynRM. Meanwhile, a brief comparison is made in terms of radial forces and power losses; the effects produced by UBW, UESW, and UOSW compared to CBW in these two aspects are acceptable.