Analysis of Electro-Mechanical Actuator Systems in More Electric Aircraft Applications

126 Pages·2005·4.3 MB·English

TRITA-ETS-2005-10
ISSN 1650-674x
ISRN KTH/R-0504-SE
ISBN 91-7178-099-8
May, 2005

Analysis of Electro-Mechanical
Actuator Systems in More Electric
Aircraft Applications

Mohsen Torabzadeh-Tari

DEPARTMENT OF ELECTRICAL ENGINEERING
ROYAL INSTITUTE OF TECHNOLOGY
SWEDEN
Submitted to the School of Computer Science,
Electrical Engineering and Engineering Physics, KTH,
in partial fulfilment of the requirements for the degree of
Licentiate of Technology.

Stockholm 2005

TRITA-ETS-2005-10
ISSN-1650-674x
ISRN KTH/R-0504-SE
ISBN 91-7178-099-8
© Mohsen Torabzadeh-Tari, Stockholm, 2005
To my love
Zohreh

Abstract
Abstract
Conventional hydraulic actuators in aircraft are demanding regarding
maintenance which implies high operation costs. In recent years the focus
therefore has been set on electro-hydrostatic and electro-mechanical actuators.
The aim of this work is to analyze and evaluate the possibility of introducing
electro-mechanical actuators (EMAs) in more electric aircraft applications. The
major goal is to optimize the weight of such actuator systems including the
electro-machine (electric motor) gear mechanism and power converter, without
loss of reliability. Other optimisation criteria on such solutions are low losses
and good thermal properties.
A quasi-static model approach of EMAs is used here in order to decrease the
simulation time. It is possible because the low (mechanical) and high (electrical)
frequency components are separated in the model, see [1]. The inverters and
converters are described as fictive DC-DC transformers with corresponding
efficiencies, see [2]. By introducing an object oriented approach the model is
flexible and re-usable and can be used as a framework in the future build-up of
models of entire MEA aircrafts, see [3].
Power density, cost and weight of the actuator systems are some of the
important key factors for comparing purpose and as a platform for the
dimensioning of the aircraft. The next issue becomes the scalability of the model
and the key factors, because of the diversity of the actuators used in different
parts of the MEA aircraft. Therefore the ambition is set to build up a database of
different scalable actuator solutions which among others returns these key
factors as output.

I
Abstract
Keywords
• MEA
• More Electric Aircraft
• EMA
• Electro Mechanical Actuator
• EM
• Electrical Machine
• Converter
• Inverter
• EHA
• Electro Hydrostatic Actuator
• Power-by-Wire
• Finite Element Method
• FEM
• Object Oriented
• Modelica

II
Acknowledgement
Acknowledgement
I would like to express a general gratitude to the people who have helped me in
various ways with this research and a making pleasant atmosphere in the
department.
Special thanks to Prof Göran Engdahl, for his guidance and sharing of his
experience during these years. The discussions with him are always inspiring
and fruitful. There are numerous notebooks in my bookcase containing
discussions note from our informal meetings, used often as reference in this
thesis.
I would also like to thanks the head of department Prof Roland Eriksson for
offering me this position and making a light atmosphere in the department to
work in. Mr. Peter Lönn, and Mr. Göte Berg are two other wonderful persons
who have a major part of the ordinary day-to-day work. Their helpfulness is
appreciated. The ‘administrative’ help from Mr Olle Brännwall, Mr. Jan
Timmerman, and Mrs Eva Peterson, Mrs Astrid Myhrman, and Mrs Margareta
Surjadi is also highly appreciated.
Many thanks to Mr. Lars Austrin who has shared his experience and study time
with me during these years. His generosity is highly appreciated, specially
during the numerous discussions at our home trip towards Linköping.
Thanks also to Dr Peter Thelin, Dr Freddy Magnusson, Tech. Licentiate
Maddalena Cirani, Prof Hans Peter Nee, Tech. Licentiate Mats Leksell, Dr
Karsten Kretschmar, Dr Erik Nordlund, Dr Hans Edin, and Dr Niclas Schönborg
for their patience and helpfulness when explaining the underlying physical laws
and mechanism of the rotary machines. Dr Julius Krah, whom I share my office
with, should also be mentioned. Thanks for putting up with my radio listening
during these years. Also Mr. Nathaniel Taylor is appreciated for his assistance in
Linux.
III
Acknowledgement
I would also like to express my gratitude to people behind the NFFP-discussion
group, Dr Björn Johansson, Prof Petter Krus, Mr. Jan-Erik Nowacki, Dr Jonas
Larsson, Mr. Anders Järlestål, and Mr. Hans Ellström for their insightful
discussions.
A special gratitude to Mr. Björn Hellström at ABB Research Center for his
assistance of the FEM program Ace and Mr. Lennart Stridsberg for providing
information about his innovative machine.
Finally I would like to thanks my wife for her endurance during these last three
years. Thanks for staying up until late and helping me with the numerous FEM
simulations. Without your contribution I would have been forced to simplify the
problem to verification of Ohm’s law. My parents, sisters, brother, and the rest
of the ‘BIG2’ family and relatives for their support during all the years. Without
your endless support and believe in me, I would not have reached this fare. You
are always in my heart, thought and prayers.
Mr. Janne ‘T’ Andersson, Mr. K-G Alhström, Mrs. Guje Alhström, Mr.
Abdullah Rajabi, Mrs. Eva Åberg and late Mr. Åke Åberg have always a special
place in my heart.
To the rest whom I have not mentioned, you are not forgotten and always in my
heart.
At last but not least people at FMV and Vinnova and Mr Lars Austrin from Saab
AB who once started this project and financed my research should be mentioned
and thanked. The funding and prolonging of this project is indebt to the efforts
of Mr Lars Austrin and highly appreciated.
Stockholm, May 2005

Mohsen Torabzadeh-Tari

IV
Contents
Contents
CHAPTER 1 INTRODUCTION...................................................................1
1.1 BACKGROUND........................................................................................1
1.2 AIM........................................................................................................4
1.3 OUTLINE OF THE THESIS.........................................................................5
1.4 LIST OF PUBLICATIONS ...........................................................................5
CHAPTER 2 PROBLEM INTRODUCTION .............................................7
2.1 CHARACTERISTICS OF ACTUATORS IN AIRCRAFT APPLICATION.............7
2.2 DESIGN PARAMETERS.............................................................................9
CHAPTER 3 THE ELECTRO-MECHANICAL ACTUATOR..............13
3.1 COMPONENTS OF AN ELECTRO-MECHANICAL ACTUATOR....................13
3.2 THE ELECTRICAL-MACHINE.................................................................13
3.2.1 DC Electrical Machines..................................................................15
3.2.2 Induction Electrical Machines........................................................16
3.2.3 Reluctance Electrical Machines......................................................16
3.2.4 Permanent Magnet Electrical Machines.........................................18
3.3 THE ELECTRONIC POWER CONTROL.....................................................23
3.4 THE GEAR ............................................................................................26
3.5 THE COMPLETE ACTUATOR..................................................................27
CHAPTER 4 METHODS ............................................................................29
4.1 ANALYSIS TOOLS.................................................................................29
4.2 MODELLING AND ANALYSIS.................................................................29
4.2.1 Loss Models.....................................................................................32
4.2.2 Modeling of the Permanent Magnet................................................43
4.3 OPTIMIZATION OF THE EMA................................................................45
CHAPTER 5 RESULTS...............................................................................47
5.1 INTRODUCTION.....................................................................................47
5.2 2D FEM ANALYSIS OF THE ELECTRICAL MACHINE..............................47
5.2.1 Losses..............................................................................................64
5.3 SIMPLIFIED EQUIVALENT CIRCUIT SIMULATION...................................74
5.3.1 Flight Mission Simulations .............................................................75
V
Contents
CHAPTER 6 THERMAL ANALYSIS.......................................................85
6.1 ANALYSIS TOOLS.................................................................................85
CHAPTER 7 OTHER SOLUTIONS..........................................................89
7.1 CONVENTIONAL HYDRAULIC ACTUATORS...........................................89
7.2 MAGNETOSTRICTIVE ACTUATORS........................................................90
7.3 ELECTRO-HYDROSTATIC ACTUATOR ...................................................92
CHAPTER 8 CONCLUSIONS AND FUTURE WORK..........................95
8.1 CONCLUSIONS......................................................................................95
8.2 FUTURE WORK.....................................................................................96

APPENDIX A ....................................................................................................99
APPENDIX B...................................................................................................101
REFERENCES................................................................................................103
LIST OF SYMBOLS.......................................................................................109
INDEX..............................................................................................................115

VI