Barajas Solano2017

273 Pages·2017·12.52 MB·English

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Novel active magnetic
bearings for direct drive
C-Gen linear generator

José Ignacio Barajas Solano

Doctor of Philosophy
The University of Edinburgh

2017

Ph.D – The University of Edinburgh – 2017
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Für Elisa…und Damian
For believing in me, even more than I believe in myself.
You are the reason I can say my life is beautiful.

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Abstract
This document presents a novel active magnetic levitation system. In the pursued of
this endeavour different topics related with wave energy were explore.
Climate change and energy security are the main motivation to pursued new options
for non-fossil fuels energy generation. An overview of renewable energy and
specifically of wave energy was presented. The potential for wave energy in The
United Kingdom turn out to be 75 TWh/year from wave energy, 3 times more of
what wind energy has produced in 2013. This means a massive impact on the energy
market and emission reduction.
In order to achieve this, improvements on wave energy devices have to be done. An
overview of wave energy converters was covered selecting the C-Gen as the
generator topology this document will base its studies.
Linear generator bearings are desired to have long lifespan with long maintenance
intervals. The objective is to come with an active magnetic levitation design that can
replace traditional bearings augmenting the reliability of the system.
Therefore magnetic bearings option have been reviewed and simulation
experimentations has resulted in a novel active magnetic levitation system using an
air-cored coils Halbach array acting over a levitation track. The configuration would
generate bi directional repulsion forces with respect of the levitating body.
Different software were used to analyse the magnetic field and forces generation.
Additionally a prototype was built and tested to corroborate the results. As part of the
modelling a mathematical model was explored and robust control implementation
was also realised.
Finally a scalability study of the device as well as a reliability analysis was done.
Although the reliability studies shows an increase of ten times of the mean time to
failure, the concept is not able to endure the loads acting on the generator unless the
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magnetic bearings became bigger than the generator and therefore economically
unfeasible.

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Declaration
I hereby declare that the work contained in this thesis is my own, any additional
source has been referenced properly. Furthermore, I confirm that this document has
not been submitted for any other degree or professional qualification.

___________________________________________
José Ignacio Barajas Solano

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Acknowledgements
Along five years there are so many people I would like to add in this section, but I
will try to make it brief.
I would like to acknowledge the support from CONACYT and SuperGen Marine.
Without the support of these organisations many students like me would not be able
to follow their goals. Also, I would like to thank my supervisor Markus Mueller, for
his guidance and patience. Generally I would like to express my gratitude to the IES
staff for all the help, especially to Douglas Carmichael.
As well, thanks to my brothers far away in body but not in spirit “Sopitas” and
“Perkins”, the brothers that I had the luck to find in my life path. Likewise to the
ones that shared a home far away from our home, Marisol Ochoa, Manuel Sanchez
and Adriana Contreras.
To my other colleagues and friends sharing the workplace that are always there to
share their knowledge and their good vibes, Kaswar Mostafa, Alberto Perez, Jen Hao
Wu, Ozan Keysan and Monika Kreitmair, but especially to Siraj Sabihuddin and
Joseph Burchell. Thanks for your time, your energy and your laugh.
Finally I want to thank my Son’s Godmother Damaris Medina, and my beloved Elisa
Kappe and Damian Barajas Kappe for brightening my days. I am grateful for my
family and my extended “Kappe” Family, always in my mind and my heart.
For you, I would like to cite Mercedes Sosa “Thanks to life, which has given me so
much”
“Gracias a la vida que me ha dado tanto”

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Table of Contents
Abstract ....................................................................................................................... iv
Declaration .................................................................................................................. vi
Acknowledgements .................................................................................................... vii
1 Introduction .......................................................................................................... 1
1.1 Renewable Energy ......................................................................................... 1
1.1.1 Climate change effects on the world ...................................................... 1
1.1.2 Energy security....................................................................................... 3
1.1.3 Worlds situation & Kyoto’s Protocol ..................................................... 4
1.1.4 Global Marine Energy ............................................................................ 5
1.1.5 Near future scenario for Marine Energy in the UK................................ 6
1.2 Wave energy in the UK ................................................................................. 8
1.2.1 Wave energy potential exploitation in the UK ....................................... 9
1.3 Chapter summary and thesis layout ............................................................. 13
2 Wave energy converters ..................................................................................... 15
2.1 Classifications of Wave Energy Converters ................................................ 15
2.2 Electric Power Take Off .............................................................................. 20
2.3 Reliability in generators. ............................................................................. 22
2.4 Direct Drive Generators in Wave Energy ................................................... 24
2.4.1 Linear Generators in Wave energy ...................................................... 24
2.4.1 Novel developments ............................................................................. 31
2.5 Summary and conclusion ............................................................................ 33
3 Introduction to Magnetic Bearings..................................................................... 35
3.1 Literature Review of Magnetic Bearings .................................................... 36
3.1.1 History of Magnetic bearings ............................................................... 36
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