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

Abstract

Permanent magnet synchronous machines with fractional-slot non-overlapping windings (FSPMSM), also known as tooth-coil winding permanent magnet synchronous machines (TCW PMSM), have been under intensive research during the latest decade. There are many optimization routines explained and implemented in the literature in order to improve the characteristics of this machine type.This paper introduces a new technique for torque ripple minimization in TCW PMSM. The source of torque harmonics is also described. The low order torque harmonics can be harmful for a variety of applications, such as direct drive wind generators, direct drive light vehicle electrical motors, and for some high precision servo applications.The reduction of the torque ripple harmonics with the lowest orders (6 th and 12 th ) is realized by machine geometry optimization technique using finite element analysis (FEA). The presented optimization technique includes the stator geometry adjustment in TCW PMSMs with rotor surface permanent magnets and with rotor embedded permanent magnets. Influence of the permanent magnet skewing on the torque ripple reduction and cogging torque elimination was also investigated. It was implemented separately and together with the stator optimization technique. As a result, the reduction of some torque ripple harmonics was attained.

New magnet shape for reducing torque ripple in an outer-rotor permanent-magnet machine

“…The distribution of magnetic flux density [1][2][3]13] and the variation in magnetic energy [11,13] are used to reveal the formation of torque ripple or cogging torque. In order to understand the torque behavior in the OR-SPM machine, the variation in energy that is stored in the magnetic field along the air gap of the machine should be examined.…”

Conceptual Framework of Antecedents to Trends on Permanent Magnet Synchronous Generators for Wind Energy Conversion System

“…For obtaining the optimized results of the overhang effect which is dependent on its length and rotor core material, with the aid of 2-D and 3-D FEM analysis, 2-D dynamic FEM was considered for the same [94]. Ilya Petrov, et al, (2015) present in the Tooth-Coil Winding Permanent Magnet Synchronous Machines (TCW PMSMs), 6 th torque ripple harmonic is partially produced by non-symmetrical peak flux density distributions in the stator teeth, due to the interaction of the permanent magnet flux with armature flux. The 6 th harmonic can be eliminated by teeth widths adjustment, whereas conventional skewing technique is not appropriate for the reduction of this harmonic.…”

“…The main disadvantage of the method with unequal stator teeth is that it gives the desirable results for only one working point, whereas for other loads the 6 th torque ripples harmonic increases. The described methods can be used by designers, who should be aware of these local saturations in TCW PMSMs, especially when low torque ripple is one of the design targets [97]. Hyeoksoo Hong, et al, (2011) investigated the surface-mounted permanent magnet brushless synchronous machine's permanent magnets' shape with the aid of level set based topology optimization method.…”

Influence of Stator Topologies on Average Torque and Torque Ripple of Fractional-Slot SPM Machines With Fully Closed Slots

“…Therefore, both the average torque and torque ripple need to be investigated together. According to the analysis in [14]- [15], the reason for higher torque ripple in electrical machines with alternate teeth wound windings was the higher saturation caused by subharmonic. The torque separation with the help of frozen permeability (FP) method was shown in [16]- [17].…”