Non-conventional Electrical Machines

270 Pages·9.395 MB·English

by  Abderrezak Rezzoug, Mohammed El?Hadi Zaim(auth.)

Non-conventional ElectricalMachines
Non-conventional
Electrical Machines
Edited by
Abderrezak Rezzoug
Mohammed El-Hadi Zaïm
Firstpublished2012inGreatBritainandtheUnitedStatesbyISTELtdandJohnWiley&Sons,Inc.
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Non-conventionalelectricalmachines/editedbyAbderrezakRezzoug,MohammedEl-HadiZaïm.
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Includesbibliographicalreferencesandindex.
ISBN978-1-84821-300-5
1. Electricmachinery. I.Rezzoug,Abderrezak.II.ElHadiZaïm,Mohamed.
TK2000.N582011
621.31'042--dc23
2011012248
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Table of Contents
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Chapter 1. Theoretical Tools and Materials
for Electric Machines. . . . . . . . . . . . . . . . . . . . . . . 1
Abderrezak REZZOUG and Mohammed El-Hadi ZAÏM
1.1. Theoretical tools . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1. Electromagnetism and rotating machines. . . 1
1.1.2. Mechanics of rotating machines. . . . . . . . . . 9
1.1.3. Heat exchanges in rotating machines. . . . . . 11
1.2. Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.2.1. Insulators . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.2.2. Conductors . . . . . . . . . . . . . . . . . . . . . . . . 22
1.2.3. Magnetic materials. . . . . . . . . . . . . . . . . . . 25
1.3. Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . 35
Chapter 2. Low-speed Teeth Coupling
Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Daniel MATT, Abdel Mounaïm TOUNZI and
Mohammed El-Hadi ZAÏM
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.2. Positioning of the problem. Outline of the
feasibility limits . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.2.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . . 41
vi Non-conventionalElectricalMachines
2.2.2. Mass or volume performances of electric
machines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.2.3. Influence of the electromechanical
conversion frequency. . . . . . . . . . . . . . . . . . . . . . 44
2.2.4. Density of electromagnetic force . . . . . . . . . 51
2.2.5. Limit values of mass torque . . . . . . . . . . . . 58
2.2.6. Comparison with the use of a gear motor . . . 61
2.3. Teeth coil winding and toothed pole
machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
2.3.1. Teeth coil winding VRM . . . . . . . . . . . . . . . 63
2.3.2. Toothed pole VRM . . . . . . . . . . . . . . . . . . . 67
2.3.3. Excited toothed poles machines. . . . . . . . . . 71
2.4. Machines with distributed winding and the
Vernier effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
2.4.1. Variable reluctance machine. . . . . . . . . . . . 82
2.4.2. Permanent magnets Vernier machine . . . . . 103
2.5. Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . 112
Chapter 3. High-speed Electric Machines . . . . . . . 117
Mohammed El-Hadi ZAÏM, Hamid Ben AHMED and
Nicolas BERNARD
3.1. Interest in high-speed rotational operating . . . . 117
3.2. Criteria and constraints of a high-speed
machine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
3.2.1. Mechanical performance. . . . . . . . . . . . . . . 121
3.2.2. Magnetic losses . . . . . . . . . . . . . . . . . . . . . 126
3.2.3. Aerodynamic losses . . . . . . . . . . . . . . . . . . 133
3.2.4. Guidance system . . . . . . . . . . . . . . . . . . . . 135
3.2.5. Consequences and performance limits . . . . . 139
3.3. Types of electric machines . . . . . . . . . . . . . . . . 142
3.3.1. Induction machine. . . . . . . . . . . . . . . . . . . 142
3.3.2. Synchronous machines. . . . . . . . . . . . . . . . 144
3.3.3. Doubly-salient variable reluctance
machine (DSVRM) . . . . . . . . . . . . . . . . . . . . . . . 151
3.4. Examples of applications. . . . . . . . . . . . . . . . . 152
3.4.1. High-speed machining (HSM) . . . . . . . . . . . 153
TableofContents vii
3.4.2. Pumping and compression at very
high speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
3.4.3. Kinetic energy storage . . . . . . . . . . . . . . . . 160
3.5. Methodology of high-speed machine
optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
3.5.1. Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . 169
3.5.2. Optimization . . . . . . . . . . . . . . . . . . . . . . . 175
3.5.3. Conclusion on the maximization of
volumic power . . . . . . . . . . . . . . . . . . . . . . . . . . 184
3.6. Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . 184
Chapter 4. Superconducting Machines . . . . . . . . . 191
Abderrezak REZZOUG, Jean LÉVÊQUE and Bruno DOUINE
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 191
4.2. Superconducting materials in
electrotechnology. . . . . . . . . . . . . . . . . . . . . . . . . . 192
4.2.1. Superconductivity . . . . . . . . . . . . . . . . . . . 193
4.2.2. Critical quantities . . . . . . . . . . . . . . . . . . . 194
4.3. Superconducting materials used in electric
machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
4.3.1. LTS superconductors . . . . . . . . . . . . . . . . . 202
4.3.2. HTS superconductors . . . . . . . . . . . . . . . . . 204
4.4. Losses in the self-field of superconductors . . . . . 212
4.4.1. Origin of losses and the Bean model. . . . . . . 213
4.4.2. Assessment of losses. . . . . . . . . . . . . . . . . . 214
4.5. Cryogenic environment . . . . . . . . . . . . . . . . . . 216
4.5.1. Mechanical properties of materials at low
temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
4.5.2. Cryogenic fluids. . . . . . . . . . . . . . . . . . . . . 219
4.5.3. Getting low temperature. . . . . . . . . . . . . . . 223
4.5.4. Cryostat . . . . . . . . . . . . . . . . . . . . . . . . . . 230
4.5.5. Vacuum techniques . . . . . . . . . . . . . . . . . . 234
4.6. Superconducting machines. . . . . . . . . . . . . . . . 235
4.6.1. Synchronous machine with a
superconducting field system . . . . . . . . . . . . . . . . 237
4.6.2. Homopolar motor . . . . . . . . . . . . . . . . . . . . 242
viii Non-conventionalElectricalMachines
4.6.3. Superconducting screen motor. . . . . . . . . . . 245
4.6.4. Flux barrier motor. . . . . . . . . . . . . . . . . . . 246
4.6.5. Hysteresis motor . . . . . . . . . . . . . . . . . . . . 247
4.6.6. Cold magnet motor. . . . . . . . . . . . . . . . . . . 249
4.7. Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . 250
List of Authors. . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Introduction
The world of electric machines, which is in a constant
state of evolution, is seeing its field of application growing
every day.
The electric machine, historically connected to a network
which supplies it with a constant voltage, is today almost as
a matter of course fed by a static terminal converter whose
voltage varies at a rapid rate, even when its average value is
constant or slowly variable.
If it appears obvious to consider the machine as one
element in an electromechanical conversion chain, most of
the time with a control system, the fact remains that for
each new class of application, the electric machine must be
examined as such.
This examination is imposed by the function itself, by the
movement to be achieved, the requisite security for each
element of the electromechanical conversion chain, the
limitation in size, the reduction in weight, the high speed
and/or the high acceleration to be reached.
In order to respond to increasingly demanding
specifications, machine construction has evolved, first of all,
thanks to progress made in the development of constituent
x Non-conventionalElectricalMachines
materials: magnetic materials (ferromagnetic powders,
permanent magnets and massive superconductors) and
insulating or conductive materials (superconducting wire).
The tools of calculation, software and material, make up
another aspect among those which have allowed progress in
the design of machines; we are considering here the tools
used to calculate fields (magnetic, electrical, thermal, force
and stress fields), 3D modeling tools and optimization tools.
If the representation models progress continually in order
to take into account more accurately geometric shapes
(including teeth harmonics, mechanical failure), nonlinearity
due to magnetic (saturation and hysteresis) or electrical
behaviors (law E(J) for superconductors), nothing can replace
the experience drawn from the achievements.
Nevertheless, the development of tools and the refinement
of modeling allow us to perform numerous simulations
leading to substantial economies in the design of prototypes
and finished products.
This book aims to tackle a subject where even the
definition is difficult to determine. What is a non-
conventional machine?
The principles of functioning rely completely on the
interaction between a magnetic field and a current (as in the
majority of electric machines) or on field-to-field interaction
(as in magnetic transmitters).
The movement of another category of electromagnetic
motor is due to the distortion of the materials themselves
(piezoelectric, shape, memory and magnetostrictive
material).
Introduction xi
This second category, made more popular, particularly by
piezoelectric motors, constitutes a specific family in the area
of electromagnetic converters and will not be tackled in this
publication.
In the category of electromagnetic machines, non-
conventional electromagnetic machines can be defined in
several ways, and this is in no way the least of our
difficulties.
We can attempt to provide a definition starting from the
following points:
– the type of movement produced by the machine itself
(rotation, linear movement, alternating movement, etc.);
– the number of degrees of freedom required (rotation or
movement on one axis, combination of the two, multi-axis
movement, spherical movement, etc.);
– required speeds (high, low);
– the number of coils installed and the distribution of the
magnetic field;
– the geometry of the magnetic circuit (structure of the
whole machine: cylindrical, flat, hollow, conical, salient or
smooth structure, position of the magnets, structure of the
teeth-slots);
– the materials utilized (permanent magnets,
superconductors, non-ferromagnetic materials, etc.);
– the dynamic characteristics (electrical and mechanical
response times, dynamic impedance, etc.);
– the forms of voltage or current delivered by its power
source (voltage form and amplitude, quality of the current,
etc.).