Unequal Teeth Widths for Torque Ripple Reduction in Permanent Magnet Synchronous Machines With Fractional-Slot Non-Overlapping Windings

摘要

Permanent magnet synchronous machines withfractional-slot non-overlapping windings (FSPMSM), also knownas tooth-coil winding permanent magnet synchronous machines(TCW PMSM), have been under intensive research during thelatest decade. There are many optimization routines explainedand implemented in the literature in order to improve thecharacteristics of this machine type.This paper introduces a new technique for torque rippleminimization in TCW PMSM. The source of torque harmonics isalso described. The low order torque harmonics can be harmfulfor a variety of applications, such as direct drive wind generators,direct drive light vehicle electrical motors, and for some highprecision servo applications.The reduction of the torque ripple harmonics with the lowestorders (6th and 12th) is realized by machine geometry optimizationtechnique using finite element analysis (FEA). The presentedoptimization technique includes the stator geometry adjustmentin TCW PMSMs with rotor surface permanent magnets and withrotor embedded permanent magnets. Influence of the permanentmagnet skewing on the torque ripple reduction and coggingtorque elimination was also investigated. It was implementedseparately and together with the stator optimization technique.As a result, the reduction of some torque ripple harmonics wasattained.