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Analysis of harmonic field effects in reluctance synchronous machines
Author(s)
Heyns, Gideon Christiaan
Date Issued
2011
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
The reluctance synchronous machine (RSM) is a type of synchronous machine which has no
windings in the rotor and can be referred to as a non-excited synchronous machine. The RSM
can be classified as either single or double salient machine. The single salient machine refers
to saliency in the rotor only and double saliency refers to saliency in the rotor and stator. The
RSM is based on the principle of reluctance, were torque is produced due to different
reluctance paths within the rotor of the machine. The term reluctance is referred to the
resistance of a material towards the flow of magnetic field.
Since the invention of vector controlled drives, RSMs regained the popularity of researchers
and are becoming a field of interest. The RSM have numerous advantages, besides being
cheap, robust, and reliable, the stator part is exactly the same as an induction machine. This
will enable easy and cost efficient upgrades. Furthermore due to the non existing rotor
currents heat dissipation will be low. However the RSM has an inherently high torque ripple
due to its rotor geometry. The torque ripple is defined as the difference between maximum
and minimum deviation of the torque referred to the average torque. The torque ripple creates
uneven pull on the rotor which creates deformation of the rotor and consequently uneven run.
As a result the torque ripple indicates that the speed of the RSM changes permanently. The
machines designers ultimate goal would be to design a machine with the lowest torque ripple
combined with a maximum average torque. The aim of this thesis is to provide a detailed
analysis on the field quantities and its harmonics of a RSM and to examine the effects which
these harmonics have on the torque production. This analysis would give designers a better
understanding of the principles of RSMs and help to obtain certain performance results. The
research design and methodology will include the harmonic content of the flux density
components in the center of the air gap. The flux density components will be analysed in
terms of its harmonics and the torque produced by these flux density harmonics will also be
investigated.
windings in the rotor and can be referred to as a non-excited synchronous machine. The RSM
can be classified as either single or double salient machine. The single salient machine refers
to saliency in the rotor only and double saliency refers to saliency in the rotor and stator. The
RSM is based on the principle of reluctance, were torque is produced due to different
reluctance paths within the rotor of the machine. The term reluctance is referred to the
resistance of a material towards the flow of magnetic field.
Since the invention of vector controlled drives, RSMs regained the popularity of researchers
and are becoming a field of interest. The RSM have numerous advantages, besides being
cheap, robust, and reliable, the stator part is exactly the same as an induction machine. This
will enable easy and cost efficient upgrades. Furthermore due to the non existing rotor
currents heat dissipation will be low. However the RSM has an inherently high torque ripple
due to its rotor geometry. The torque ripple is defined as the difference between maximum
and minimum deviation of the torque referred to the average torque. The torque ripple creates
uneven pull on the rotor which creates deformation of the rotor and consequently uneven run.
As a result the torque ripple indicates that the speed of the RSM changes permanently. The
machines designers ultimate goal would be to design a machine with the lowest torque ripple
combined with a maximum average torque. The aim of this thesis is to provide a detailed
analysis on the field quantities and its harmonics of a RSM and to examine the effects which
these harmonics have on the torque production. This analysis would give designers a better
understanding of the principles of RSMs and help to obtain certain performance results. The
research design and methodology will include the harmonic content of the flux density
components in the center of the air gap. The flux density components will be analysed in
terms of its harmonics and the torque produced by these flux density harmonics will also be
investigated.
Additional information
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2011.
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20117227_Heyns_GC_Mtech_Elec_Eng_2011_20117227.pdf
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Thesis
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