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A practical investigation into the measurement of forces on the stator teeth of electrical machines
Author(s)
Bevan, Graeme Rhys
Date Issued
2013
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Radial and peripheral displacement of stator teeth in electrical machines is known to be
the cause of undesired vibration which leads to noise. This thesis serves to investigate the
possibility of physically measuring the radial displacement of stator teeth caused by
electromagnetic forces which, to the author’s knowledge, has not yet been achieved. A
simplified practical approach is adopted in order to address the inherent difficulties
attached to this problem, and the measurement of displacement is done by means of an
experimental rig where a tooth is subjected to magnetic force acting over an air gap.
Three experiments are carried out, each comprising ten tests, the results of which are
compared in order to gain some idea as to the magnitudes of displacement which can be
expected over a range of applied air gap flux densities. The aim of this work is to observe
the displacement response of magnetised EM core material when acted upon by forces,
and to see if the measured results agree with the elastic displacement predicted by a wellknown
formula. It will be shown that although the measured results are in the same range
as the predicted results, there is a deviation from the predicted linearity due to certain
characteristics of the force rig, which are explained.
The chosen measurement method is capacitive displacement and is shown to be a viable
alternative to the more commonly used search coils and vibrometers in past literatures,
especially when measuring displacements on the nano-scale. In addition, this study shows
the importance of using 3D finite element software to simulate the electromagnetic model
when saturation is present in the core of the test specimen. The important findings of this
work are discussed in detail, and some ideas put forward, in an attempt to establish a
starting point for future related work in the measurement of electromagnetic forceinduced
displacement of stator teeth in electrical machines.
the cause of undesired vibration which leads to noise. This thesis serves to investigate the
possibility of physically measuring the radial displacement of stator teeth caused by
electromagnetic forces which, to the author’s knowledge, has not yet been achieved. A
simplified practical approach is adopted in order to address the inherent difficulties
attached to this problem, and the measurement of displacement is done by means of an
experimental rig where a tooth is subjected to magnetic force acting over an air gap.
Three experiments are carried out, each comprising ten tests, the results of which are
compared in order to gain some idea as to the magnitudes of displacement which can be
expected over a range of applied air gap flux densities. The aim of this work is to observe
the displacement response of magnetised EM core material when acted upon by forces,
and to see if the measured results agree with the elastic displacement predicted by a wellknown
formula. It will be shown that although the measured results are in the same range
as the predicted results, there is a deviation from the predicted linearity due to certain
characteristics of the force rig, which are explained.
The chosen measurement method is capacitive displacement and is shown to be a viable
alternative to the more commonly used search coils and vibrometers in past literatures,
especially when measuring displacements on the nano-scale. In addition, this study shows
the importance of using 3D finite element software to simulate the electromagnetic model
when saturation is present in the core of the test specimen. The important findings of this
work are discussed in detail, and some ideas put forward, in an attempt to establish a
starting point for future related work in the measurement of electromagnetic forceinduced
displacement of stator teeth in electrical machines.
Additional information
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2013
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Bevan_GR_ MTech Thesis.pdf
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Thesis
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