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Analysis and control of magnetic forces in synchronous machines
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.ORCID iD: 0000-0003-4265-6545
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Description
Abstract [en]

In a synchronous machine, radial, tangential, and axial forces are generated. In this thesis, three different technologies to control them are proposed. The first one, involves the utilization of the radial forces that arise between the rotor and the stator. This is achieved by segmenting the rotor field winding into groups of poles and controlling their corresponding magnetization individually. This technology is particularly useful to achieve magnetic balance and to create controllable radial forces. The second technology, involves the control of the rotor field in order to influence the tangential forces that produce torque. This is achieved by inverting the rotor field winding polarity with respect to the stator field. With this technique, breaking and accelerating torques can be created. It is particularly useful to start a synchronous machine. Finally, the application of axial forces with a magnetic thrust bearing is discussed. The main benefits of this technology are higher efficiency and increased reliability.

The work presented in this thesis was carried out within the Division of Electricity in the Department of Engineering Sciences at Uppsala University. It is based on original research supported by analytical calculations, computational simulations and extensive experimental work.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. , 84 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1542
Keyword [en]
eccentricity, electromagnetics, electromagnetic forces, excitation, magnetic fields, magnetic forces, magnetic thrust bearing, rotor drive, split rotor, starting, synchronous generators, synchronous machines, synchronous motors, unbalanced magnetic pull
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-328086ISBN: 978-91-513-0036-8 (print)OAI: oai:DiVA.org:uu-328086DiVA: diva2:1133828
Public defence
2017-10-06, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2017-09-13 Created: 2017-08-16 Last updated: 2017-09-13
List of papers
1. Arrangement for supporting a rotatable body
Open this publication in new window or tab >>Arrangement for supporting a rotatable body
2016 (English)Patent (Other (popular science, discussion, etc.))
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328389 (URN)
Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-08-24
2. Fail-safe system for discharging a magnetic thrust bearing
Open this publication in new window or tab >>Fail-safe system for discharging a magnetic thrust bearing
2016 (English)Patent (Other (popular science, discussion, etc.))
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328390 (URN)
Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-08-24
3. Comparison of Thyristor Rectifier Configurations for a Six-Phase Rotating Brushless Outer Pole PM Exciter
Open this publication in new window or tab >>Comparison of Thyristor Rectifier Configurations for a Six-Phase Rotating Brushless Outer Pole PM Exciter
Show others...
2017 (English)In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. PP, no 99, 1-1 p.Article in journal (Refereed) Epub ahead of print
Keyword
Bridge circuits;Generators;Shafts;Thyristors;Topology;Torque;Windings;12-pulse thyristor rectifiers;Fast-response exciters;active rectification;brushless exciters;hybrid-mode operation;multiphase machines;outer-pole PM machines;rotating exciters;synchronous generators
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328391 (URN)10.1109/TIE.2017.2726963 (DOI)
Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-08-24
4. Evaluation of different power electronic interfaces for control of a rotating brushless PM exciter
Open this publication in new window or tab >>Evaluation of different power electronic interfaces for control of a rotating brushless PM exciter
Show others...
2016 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328394 (URN)
Conference
42nd annual conference of the IEEE Industrial Electronics Society
Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-08-24
5. Testing of Active Rectification Topologies on a 6-Phase Rotating Brushless Outer Pole PM Exciter
Open this publication in new window or tab >>Testing of Active Rectification Topologies on a 6-Phase Rotating Brushless Outer Pole PM Exciter
Show others...
2017 (English)In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. PP, no 99, 1-9 p.Article in journal (Refereed) Epub ahead of print
Abstract [en]

The static exciter is dominating among large grid- connected generators due to the weak dynamic performance of conventional brushless exciters. In this contribution, a six-phase double-star outer pole permanent magnet rotating brushless exciter is evaluated with different active rectification topolo- gies. Both thyristor-based and chopper-based topologies are considered. A high speed response brushless excitation system is obtained by replacing the conventional rotating diode bridge rectifier with the proposed active rectification topologies on the shaft. The given two-stage system generates its own excitation power directly from the shaft, contrary to static exciters. The selection of an appropriate rectification topology could minimize the rotor armature phase currents for a given generator field current. The objective is a high power factor and a high uti- lization of the exciter machine. An optimal rectification topology makes higher ceiling currents possible, improving the transient behavior of the synchronous generator. In this paper, we show that six-phase topologies add complexity, but improve exciter redundancy, increase the available ceiling voltage and reduce the steady state torque ripple. Experimental results are given for validating the models implemented for the analysis.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-328396 (URN)10.1109/TEC.2017.2746559 (DOI)
Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-08-31
6. Optimization of Force Between Cylindrical Permanent Magnets
Open this publication in new window or tab >>Optimization of Force Between Cylindrical Permanent Magnets
2014 (English)In: IEEE Magnetics Letters, ISSN 1949-307X, Vol. 5, 0800404- p.Article in journal (Refereed) Published
Abstract [en]

We calculated analytically and with the finite-element method the force between two identical coaxial cylindrical magnets for nine different magnetic materials at separations of 1, 3, 5, 7, and 9 mm and for height-to-diameter ratios between 0.1 and 2. For the analytical calculations, we assumed homogeneous magnetization. For the nonhomogeneous case, we used the finite-element method taking into consideration the magnetic flux density vs. field (B-H) curves of the materials. The results show that, similarly for cuboid magnets, the maximum force for a given volume of permanent-magnet material was achieved for a height-to-diameter ratio around 0.4 for homogeneously magnetized (ideal) permanent magnets. We also show that this is not always true for the nonhomogeneous cases. The resulting forces are dependent on the B-H curve of the magnets. As the B-H curves of the materials deviate from their ideal counterparts, the aspect ratio that yields maximum force increases.

Keyword
Electromagnetics, electromagnetic forces, hard magnetic materials, magnetic forces
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-246202 (URN)10.1109/LMAG.2014.2363438 (DOI)000347916300004 ()
Available from: 2015-03-03 Created: 2015-03-03 Last updated: 2017-08-16Bibliographically approved
7. Performance tests of a permanent magnet thrust bearing for a hydropower synchronous generator test-rig
Open this publication in new window or tab >>Performance tests of a permanent magnet thrust bearing for a hydropower synchronous generator test-rig
2017 (English)In: ACES JournalArticle in journal (Refereed) Accepted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328078 (URN)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
8. Simple Method to Calculate the Force between Thin Walled Solenoids
Open this publication in new window or tab >>Simple Method to Calculate the Force between Thin Walled Solenoids
2016 (English)In: Progress In Electromagnetics Research M, Vol. 51, 93-100 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
EMW Publishing, 2016
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328077 (URN)10.2528/PIERM16062307 (DOI)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-16
9. Demonstration of synchronous motor start by rotor polarity inversion
Open this publication in new window or tab >>Demonstration of synchronous motor start by rotor polarity inversion
2017 (English)In: Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328081 (URN)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
10. Electromagnetic losses in synchronous machines during active compensation of unbalanced magnetic pull due to static eccentricity
Open this publication in new window or tab >>Electromagnetic losses in synchronous machines during active compensation of unbalanced magnetic pull due to static eccentricity
2017 (English)In: Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328080 (URN)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
11. Demonstration of active compensation of unbalanced magnetic pull in synchronous machines
Open this publication in new window or tab >>Demonstration of active compensation of unbalanced magnetic pull in synchronous machines
2017 (English)In: CIGRE Science & Engineering, Vol. 8, 98-107 p.Article in journal (Refereed) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328079 (URN)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
12. Arrangement and method for force compensation in electrical machines
Open this publication in new window or tab >>Arrangement and method for force compensation in electrical machines
2016 (English)Patent (Other (popular science, discussion, etc.))
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328083 (URN)
Patent
SE SE538502C2
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-16
13. Synchronous machine and method for operating a synchronous machine
Open this publication in new window or tab >>Synchronous machine and method for operating a synchronous machine
2017 (English)Patent (Other (popular science, discussion, etc.))
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328085 (URN)
Patent
SE SE1750223-8
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
14. Magnetic thrust bearing for a hydropower unit with a Kaplan turbine
Open this publication in new window or tab >>Magnetic thrust bearing for a hydropower unit with a Kaplan turbine
2017 (English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-328082 (URN)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-23
15. Design and Characterization of a Rotating Brushless Outer Pole PM Exciter for a Synchronous Generator
Open this publication in new window or tab >>Design and Characterization of a Rotating Brushless Outer Pole PM Exciter for a Synchronous Generator
Show others...
2017 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 53, no 3, 2016-2027 p.Article in journal, Letter (Refereed) Published
Abstract [en]

Generally, PM machines are used as PMG pre-exciters in 3-stage brushless excitations systems. This paperpresents the design, characterization and prototyping of a rotatingbrushless PM exciter used in a proposed 2-stage excitation systemfor a synchronous generator. The proposed design reduces thenumber of components compared with conventional systems.A comparison with the state-of-the-art conventional excitationsystems is given. The design of a fast-response, or high initialresponse, brushless exciter requires active rectification on therotating frame, replacing the non-controllable diode bridge. Theobjective was to construct an exciter with the capability of a50 Aoutput field current as well as a high value of the available ceilingvoltage and ceiling current. The final exciter was constructed to befitted into an in-house synchronous generator test setup. A finiteelement model of the exciter was validated with experimentalmeasurements. The exciter prototype is also compared with analternative armature design with non-overlapping single-layerconcentrated windings but with the same main dimensions.The paper includes a general design procedure suitable foroptimization of PM brushless exciters that fulfill the requirementsof their synchronous generators and the grid.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-315594 (URN)10.1109/TIA.2017.2669890 (DOI)
Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2017-08-24Bibliographically approved
16. Passive Axial Thrust Bearing for a Flywheel Energy Storage System
Open this publication in new window or tab >>Passive Axial Thrust Bearing for a Flywheel Energy Storage System
Show others...
2013 (English)Conference paper, Published paper (Refereed)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-212104 (URN)
Conference
The 1st Brazilian Workshop on Magnetic Bearings
Available from: 2013-12-05 Created: 2013-12-05 Last updated: 2017-08-24
17. Magnetic Modeling and Measurement of Forces Between Permanent Magnet Rings used as Passive Magnetic Bearings
Open this publication in new window or tab >>Magnetic Modeling and Measurement of Forces Between Permanent Magnet Rings used as Passive Magnetic Bearings
Show others...
2013 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Rio de Janeiro, Brazil: , 2013
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-212880 (URN)
Conference
1st Brazilian Workshop on Magnetic Bearings, BWMB 2013
Available from: 2013-12-16 Created: 2013-12-16 Last updated: 2017-08-24
18. Eddy Currents in a Passive Magnetic Axial Thrust Bearing for a Flywheel Energy Storage System
Open this publication in new window or tab >>Eddy Currents in a Passive Magnetic Axial Thrust Bearing for a Flywheel Energy Storage System
Show others...
(English)In: International journal of applied electromagnetics and mechanics, ISSN 1383-5416, E-ISSN 1875-8800Article in journal (Refereed) In press
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-317880 (URN)
Available from: 2017-03-21 Created: 2017-03-21 Last updated: 2017-08-24
19. Design and characterization of a rotating brushless PM exciter for a synchronous generator test setup
Open this publication in new window or tab >>Design and characterization of a rotating brushless PM exciter for a synchronous generator test setup
Show others...
2016 (English)In: Design and characterization of a rotating brushless PM exciter for a synchronous generator test setup / [ed] IEEE Xplore, 2016, 259-265 p.Conference paper, Published paper (Refereed)
Abstract [en]

This paper deals with the characterization and construction of a rotating brushless PM exciter intended for synchronous generator excitation purposes. Traditionally, PM exciters are used as pre-exciters in synchronous generator excitations systems. In order to reduce the number of components and to increase the step time response of the system, a PM exciter is designed as an outer pole PM machine, with permanent magnets on the stator and armature windings on the rotor. The exciter was constructed electrically and mechanically to be fitted into an in-house synchronous generator test setup. A finite element model of the exciter was validated with no-load measurements of voltages and magnetic flux densities. The exciter was then characterized with unsaturated and saturated parameters.

Keyword
Brushless exciters, rotating exciters, permanent magnet machines, machine design, voltage measurement
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-292798 (URN)10.1109/ICELMACH.2016.7732536 (DOI)000390884900037 ()9781509025381 (ISBN)
Conference
International Conference on Electrical Machines 2016 (ICEM'16), Lausanne, SWITZERLAND, SEP 04-07, 2016
Available from: 2016-05-09 Created: 2016-05-09 Last updated: 2017-08-24Bibliographically approved
20. Initial Performance Tests of a Permanent Magnet Thrust Bearing for a Hydropower Synchronous Generator Test-Rig
Open this publication in new window or tab >>Initial Performance Tests of a Permanent Magnet Thrust Bearing for a Hydropower Synchronous Generator Test-Rig
2016 (English)Conference paper, Abstract (Refereed)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-284944 (URN)
External cooperation:
Conference
AIM 2016
Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2017-08-24
21. Analysis of passive magnetic bearings for kinetic energy storage systems
Open this publication in new window or tab >>Analysis of passive magnetic bearings for kinetic energy storage systems
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Linz, Austria: , 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-237550 (URN)
Conference
14th International Symposium on Magnetic Bearings
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2017-08-24
22. Passive Magnetic Bearing System
Open this publication in new window or tab >>Passive Magnetic Bearing System
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Rio de Janeiro, Brazil: , 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-237551 (URN)
Conference
22nd International Conference on Magnetically Levitaded Systems and Linear Drives
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2017-08-24
23. Construction of a Permanent Magnet Thrust Bearing for a Hydropower Generator Test Setup
Open this publication in new window or tab >>Construction of a Permanent Magnet Thrust Bearing for a Hydropower Generator Test Setup
2013 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Rio de Janeiro, Brazil: , 2013
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-212881 (URN)
Conference
1st Brazilian Workshop on Magnetic Bearings, BWMB 2013
Available from: 2013-12-16 Created: 2013-12-16 Last updated: 2017-08-24

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Citation style
  • apa
  • ieee
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