DIMENSIONING TOOLS OF MEA ACTUATOR - DiVA Portal

142 Pages·2008·7.12 MB·English

DIMENSIONING TOOLS OF MEA ACTUATOR
SYSTEMS, INCLUDING MODELING, ANALYSIS
AND TECHNOLOGY COMPARISON
MOHSEN TORABZADEH-TARI
Doctoral Thesis
Stockholm, Sweden 2008
Cover page illustrates an Unmanned Aerial Vehicle (Courtesy of SAAB AB).
Elektroteknisk teori och konstruktion
TRITA-EE 2008:050 Teknikringen 33
ISSN 1653-5146 SE-100 44 Stockholm
ISBN 978-91-7415-157-2 SWEDEN
Akademisk avhandling som med tillst(cid:23)and av Kungl Tekniska h(cid:127)ogskolan framl(cid:127)agges
tillo(cid:11)entliggranskningf(cid:127)oravl(cid:127)aggandeavteknologiedoktorsexamenm(cid:23)andagenden
15 December 2008 klockan 10.00 i H1, Teknikringen 33, Kungl Tekniska h(cid:127)ogskolan
, Stockholm.
(cid:13)c Mohsen Torabzadeh-Tari, December 2008
Tryck: Universitetsservice US AB
iii
Abstract
Aircraftdesignisanexampleofcomplexengineeringwheredimensioningtoolscanbevalu-
able for the designers and decision makers in the early stage of the development process.
These tools can be in form of a database over key numbers for di(cid:11)erent components or
technologies.
Oneofthecriticalpartsofanaircraftistheactuatorsystem. Conventionalhydraulicactu-
atorsaredemandingregardingmaintenancewhichimplieshighoperationcosts. Therefore
inrecentyearsthefocushasbeensetonelectro-hydrostaticandelectro-mechanicalactu-
ators.
The aim of this work is to build a platform which can make it easier for designers and
decisionmakerstoanalyze,compareandoptimizedi(cid:11)erenttechnologiesregardingtheac-
tuator system.
For this reason a simpli(cid:12)ed quasi-static actuator model, including reactive power con-
sumption has been developed. This model makes it possible to reduce the complexity of
the actuator models to such extent that the resulting computional tool can be used for
studies of the system performance during entire (cid:13)ight missions and/or for optimization.
Power density, cost and weight of the actuator systems are some of the important key
numbers for comparing purpose and as a platform for the dimensioning of the aircraft.
The ambition is then to build up a database of di(cid:11)erent actuator solutions with the key
technicalparametersmentionedabove,thatcanbeusedinmodelinganddimensioningof
an aircraft.
In order to avoid time consuming (cid:12)nite element calculations when analyzing an electrical
machineareluctancenetworkmodelcanbeused. Thebasicideaoftheproposednetwork
model is to divide the rotor and the stator into a grid of small reluctance elements and
providethosethatcorrespondtothepermanentmagnetandtheairgapbetweenthemag-
nets with time varying reluctances. The suggested computationally approach constitute
a fast way to evaluate permanent magnet electrical machines with the respect to their
performance.
A preferred electrical machine provided with balance teeth and concentrated windings
showedgoodelectromechanicalandthermalbehavior. Abalancetoothisatoothwithout
winding between each adjacent phases that has a cooling e(cid:11)ect on the nearest windings,
resulting in less copper losses. The balance teeth increases the voltage-time area, leading
to higher induced voltage and higher torque production. Another advantage of the cho-
sen design is its redundancy and fault tolerance capabilities. The machine comprises two
independent half machines that also o(cid:11)ers a high level of redundancy with two separate
power channels.
Keywords: Dimensioning tools, MEA, More Electric Aircraft, EMA, Electro Mechani-
calActuator,EM,ElectricalMachine,Converter,Inverter,FiniteElementMethod,FEM,
Reluctance Network

Acknowledgments
Iwouldliketoexpressageneralgratitudetothepeoplewhohavehelpedmeinvar-
iouswayswiththisresearchandcreatingapleasantatmosphereatthedepartment.
I owe an enormous debt of gratitude to my advisor, Prof G(cid:127)oran Engdahl, for his
guidanceandsharingofhisexperienceduringtheseyears. Hisprofoundknowledge
andmasterlycreativethinkinghavebeenmysourceofinspirationthroughoutthis
work.
IwouldalsoliketothankstheheadofdepartmentProfRolandErikssonforo(cid:11)ering
me this position and making a light atmosphere in the department to work in. Mr.
Peter L(cid:127)onn, and former employee Mr. G(cid:127)ote Berg are two other wonderful persons
who have a major part of the ordinary day-to-day work. Their helpfulness is ap-
preciated. The ’administrative’ help from Mr Olle Br(cid:127)annwall, Mrs Eva Peterson,
Mrs Margareta Surjadi, and Brigitt H(cid:127)ogberg is also highly appreciated.
Many thanks to Tech. Licentiate Lars Austrin who has shared his experience and
study time with me during these years. His generosity is highly appreciated, spe-
cially during the numerous discussions at our home trip towards Link(cid:127)oping.
I must mention some of those who made valuable input to my work. Thanks also
to Dr Peter Thelin for his patience and helpfulness when explaining the underlying
physical laws and mechanism of the rotary machines. Mr Hanif Tavakoli, whom
I share my o(cid:14)ce with during the last year, should also be mentioned. Thanks
for putting up with my radio listening. Also Tech. Licentiate Nathaniel Taylor
is appreciated for his assistance in Linux and Latex. and Tech. Licentiate David
Ribbenfj(cid:127)ard for his assistance with the material measurments.
I would also like to express my gratitude to people behind the NFFP-discussion
group,DrBj(cid:127)ornLunde(cid:19)n,ProfPetterKrus,Mr. Jan-ErikNowacki,Mr. AndersJ(cid:127)ar-
lest(cid:23)al,andMr. HansEllstr(cid:127)omfortheirinsightfuldiscussions,supportandguidance
during this study. A special gratitude to Mr. Bj(cid:127)orn Hellstr(cid:127)om at ABB Research
Center for his assistance of the FEM program Ace and Mr. Lennart Stridsberg for
providing information about his innovative machine.
v
vi ACKNOWLEDGMENTS
Finally I would like to thanks my wife for her endurance during these last couple
of years. My parents, sisters, brother, and the rest of the ’BIG2’ family, relatives
and friends for their support during all the years. Without your endless support,
love and believe in me, I would not have reached this fare. You are always in my
heart,thoughtandprayers. AlsotheassistanceofmyniecesandtheirfriendDenise
regarding the drawings of this work is highly appreciated.
AtlastbutnotleastpeopleatFMVandVinnovaandTech. LicentiateLarsAustrin
from Saab AB who once started this project and (cid:12)nanced my research should be
mentioned and thanked. The funding and prolonging of this project is indebted to
the e(cid:11)orts of Tech. Licentiate Lars Austrin and highly appreciated.
To the rest whom I have not mentioned, you are not forgotten and always in my
heart.
Stockholm, December 2008
Mohsen Torabzadeh-Tari
Contents
Abstract iii
Acknowledgments v
Contents vii
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.3 Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4 List of Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2 Problem Description 15
2.1 Fundamental Features of an Actuator System in Aircraft Applications 15
2.2 Features of Conventional Actuator Systems . . . . . . . . . . . . . . 21
2.3 Requirements of MEA Actuator Systems . . . . . . . . . . . . . . . . 22
2.4 Key Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3 MEA Actuator System Component Inventory 29
3.1 Electrical Power Converters . . . . . . . . . . . . . . . . . . . . . . . 29
3.2 Electrical Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3 Fault Tolerance and Redundancy . . . . . . . . . . . . . . . . . . . . 51
3.4 Gear Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.5 Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.6 Cooling Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4 Technology Assessment Tools 63
4.1 Outline of an Assessment Tool for MEA Actuator Systems. . . . . . 63
4.2 Dimensioning Rules for Selection and Comparison of Components
and Technologies in MEA Actuator Systems . . . . . . . . . . . . . . 64
vii
viii CONTENTS
4.3 Examples of Usage of the Technology Assessment Algorithm to Op-
timize a MEA Actuator System . . . . . . . . . . . . . . . . . . . . . 70
5 Component Models and Analyses 73
5.1 Lumped Element Models and Analyses . . . . . . . . . . . . . . . . . 74
5.2 Thermal Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.3 Electromagnetic Finite Element Models and Analysis . . . . . . . . . 95
5.4 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6 System Simulation and Analyses 101
6.1 The Complete System Model . . . . . . . . . . . . . . . . . . . . . . 101
6.2 Simulation Examples of Flight Missions . . . . . . . . . . . . . . . . 102
6.3 The System Model as a MEA Dimensioning Tool . . . . . . . . . . . 103
6.4 Comments Regarding the Proposed Design Algorithms . . . . . . . . 103
7 Summary and Conclusions 111
7.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
7.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8 Future Work 113
8.1 Further work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
A Permanent Magnet Model 115
B Electromotive Force 117
C Abbreviation 121
Bibliography 123
Chapter 1
Introduction
In this chapter a survey of the research activities regarding More Electric Aircraft
(MEA) is presented. Although the concept can be traced back to the World War II,
MEA is not yet fully adopted in the aircraft industry, despite the advances made in
the enabling technologies.
Under the MEA concept lies the actuation function. Several studies address-
ing the di(cid:14)culties of introducing an electromechanical or electro-hydraulic actuator
instead of the conventional hydraulic system are also pointed out in this chapter.
1.1 Background
There is a general trend in aerospace industry to increase the use of electrically
powered equipment for supplying the secondary power needs. This trend is usu-
ally referred to as "More Electric Aircraft"(MEA) towards the ultimate goal "All
Electric Aircraft (AEA)". The bene(cid:12)ts are among others lower maintenance e(cid:11)ort,
reduced weight, less Life Cycle Cost (LCC), better redundancy, and increased re-
liability. In Fig. 1.1 the present and potential MEA power system architecture of
anairlinerareshownwherethehydraulicandpneumaticsystemsarereplacedbya
hybrid or electrical systems, see also [1]. The forecasted increased electrical power
consumption on board, as a result of new or improved services such as in-(cid:13)ight
entertainment,informationservicesandpassengercomfortandnewelectricalloads
such as electrical actuation of (cid:13)ight surfaces and landing gear is also mentioned
in [2]. For meeting this requirement a power generation of 500 kW per engine is
estimated. Furthermore a summary of studies regarding the development of an
embedded generator mounted directly on the engine shaft for meeting the increas-
ing required electrical power is given in this paper. The feasibility of embedded
generators for MEA is also studied in [3].
The electrical power sources in aircraft are divided in primary and secondary
sources according to [4]. In the primary source the power/energy is transduced
from non-electrical source to electrical independent of other electrical sources. As
1
2 CHAPTER 1. INTRODUCTION
(a)Blockdiagramofpresentpowersystem. (b) Block diagram of potential MEA sys-
tem.
Figure 1.1: Example of power system architectures in an airliner, going from hy-
draulic (in red) and pneumatic (in green) systems towards more electrical systems
(in yellow).
an example of primary AC electric source the main engine-driven alternator or
Auxiliary Power Unit (APU) driven-alternator can be mentioned. A DC primary
power source can be the battery. In a secondary source the power/energy provided
fromaprimarysourceistransformedtoeitherACorDCpoweredequipment. The
historyandtheongoingprojectsduringthe90’sregardingtheMEAtechnologyare
presented in [5]. Further it is mentioned that there are three types of secondary
power sources, in both civil and military aircraft. The (cid:12)rst one is the actuation
system where hydraulics is used. In the second case, air-conditioning, pressuriza-
tion, or ice-protection pneumatics is used. The third type relates to avionics and
utility functions where electronics are used. Although the idea of MEA is not a
new one, in fact the Vickers Valliant and Vulcan used electrical power for primary
(cid:13)ight control together with a 112 VDC electrical system during the World War II,
howevertherequiredpowerforsuchelectricsystemsexceededthegeneratedpower
and therefore this approach was unfeasible until recently. Advances in enabling
technologies of electric power generation, distribution and consumption have made
MEA more competitive than before. Nevertheless only a stepwise approach has
been adopted for MEA technology until now. Now the more electric approach is
also adopted in other areas like in craft ship industries, see for example [6]. In
Fig 1.2 major components of a more electric aircraft and a ship are shown, from
references [7] and [8] respectively.
The electric brake shown in Fig. 1.3 is another component of MEA where
hydraulic system is replaced by an electromechanical. By choosing the electric
brake considerable weight and volume savings are promised in [9], as well as lower