CERN Accelerator School Specialized course on power convertors

432 Pages·2006·22.71 MB·English

CERN–2006–010
30August2006
ORGANISATION EUROP(cid:131)ENNE POUR LA RECHERCHE NUCL(cid:131)AIRE
CERN
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN Accelerator School
Specialized course on power convertors
Warrington, United Kingdom
12–18 May 2004
Proceedings
Editor: D. Brandt
GENEVA
2006
CERN–320copiesprinted–September2006
Abstract
These proceedings contain the lectures given at the eighteenth specialized course organized by
theCERNAcceleratorSchool(CAS),thetopicbeing‘PowerConvertersforParticleAccelerators’. The
coursewasheldinWarrington,UK,from12to18May2004. AsimilarcoursetookplaceinMontreux,
Switzerland in 1990, with proceedings published as CERN 90-07. After an interval of fourteen years,
the aim of this course was to present a review of the actual state of the art and highlight the latest
developmentsinthefield.
The course started with a basic recapitulation on accelerators, the required performance for the
power converters, and the classification of converter topologies. Following this introductory section,
more detailed aspects of active and passive components, converter topology analysis and simulations
were presented. Based on these building blocks, the main power converter topologies were covered
such as thyristor rectifiers, 1-quadrant and 4-quadrant switched-mode power converters. The important
problem of the high precision required for power converters in particle accelerators was exposed by
lecturesonregulationtheory,high-precisionmeasurements,ADC–DACandgeneralcontrols. Inparallel
tothis,practicalaspectswerealsoconsideredandlecturesonprotection,interlockdiagnostics,EMCand
electricalnetworkswerepresented.
The programme was completed with seminars and interactive discussions related to future chal-
lengestobemetinthefieldofpowerconverters.
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Foreword
TheaimoftheCERNAcceleratorSchool(CAS)tocollect,preserve,anddisseminatetheknowl-
edgeaccumulatedintheworld’sacceleratorlaboratoriesappliesnotonlytogeneralacceleratorphysics,
but also to related sub-systems, equipment, and technologies. This wider aim is achieved by means
of specialized courses. For 2004, the topic of the course was Power Converters and it was held at the
HanoverInternationalHotel,Warrington,UK,from12to18May2004.
Power Converters have already been treated in the framework of CAS courses, namely in 1990
in Montreux, Switzerland. However, after fourteen years and considering the enormous developments
achievedinthefield,itwasunanimouslyfeltthattherewasanurgentneedtopresentanupdatedversion
ofthepreviouscourse.
Thepresentcoursewasmadepossiblebytheactivesupportofseverallaboratoriesandmanyindi-
viduals. Inparticular,theoutstandingcontributionofthescientificco-ordinatorsDr. F.Bordry(CERN)
and N. Marks (CCLRC Daresbury), the help and encouragement of the Daresbury Laboratory manage-
mentandstaff,especiallytheenthusiasticcontributionoftheLocalOrganizingCommitteecomposedof
N.Marks,S.Griffiths,C.White,S.WallerandL.Kennedy,weremostinvaluable.
The generous financial support provided by the CCLRC Daresbury Laboratory, the DIAMOND
LightSource, ASTeC,andPPARCallowedCASandtheLocalOrganizingCommitteetobothsubstan-
tially reduce the fee for the participants and offer scholarships to highly deserving young students who
wouldotherwisenothavebeenabletoattendtheschool.
As always, the backing of the CERN management, the guidance of the CAS Advisory and Pro-
grammeCommittees,theattentiontodetailoftheLocalOrganizingCommitteeandthemanagementand
staffoftheHanoverInternationalHotelensuredthattheschoolwasheldunderoptimumconditions.
Very special thanks must go to the lecturers for the enormous task of preparing, presenting, and
writinguptheirtopics.
Finally, the enthusiasm of the participants who came from more than twenty different countries
wasconvincingproofoftheusefulnessandsuccessofthecourse.
It is my pleasure and my privilege to thank most sincerely all those persons who helped me to
makethecourseasuccess, includingtheteamoftheCERNScientificTextProcessingServicefortheir
dedicationandcommitmenttotheproductionofthisdocument.
DanielBrandt
CERNAcceleratorSchool
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Version 22 April, 2004
PROGRAMME
POWER CONVERTERS FOR PARTICLE ACCELERATORS,
Hanover International Hotel, Warrington, 12-18 May 2004
Time Wednesday Thursday Friday Saturday Sunday Monday Tuesday
12 May 13 May 14 May 15 May 16 May 17 May 18 May
08 :30 Opening Passive DAY AT Converters for Protection, Challenges for
Remarks Components DARESBURY Cycling Interlocks and The Future
09h30 Machines II Diagnostics
Fast Pulsed
Converters I
09 :30 M. Poole A. Rufer P. Smith N. Marks S. Griffiths N. Marks
09:30 Accelerator Systematical 10h30 Regulation EMC Discussion on
Basics Analysis COFFEE Theory Challenges
-------------
11h00
C. De Almeida Fast Pulsed
10:30 D. Brandt Martins Converters II F. Bordry A. Charroy F. Bordry
COFFEE P. Smith E COFFEE
11:00 Power Rectifiers 12h00 High Precision Electrical Closing
Converters and Converters for X Measurements Network and Remarks
Accelerators Cycling Power
Machines I Converters
C
12:00 N. Marks R. Visintini N. Marks G. Fernqvist H.-U. Boksberger D. Brandt
LUNCH 13h15 U LUNCH
14:00 Power Switched Mode LUNCH DAC-ADC Simulation BUSES TO
Converters Converters --------------- R Tools AIRPORT
Definitions & (1 Quadrant) L
Classifications
S
I A
15:00 F. Bordry P. Barrade J. Pickering F. Jenni
I
15:00 Power Switched Mode Controls and Demo
B
Converters Converters Interfaces
Definitions & (4 Quadrants) O
Classifications
II V N
16:00 F. Bordry Y. Thurel Q. King F. Jenni
TEA I TEA
16:30 Active Devices Seminar Seminar Seminar
ITER and The S Diamond – The Different Power
Power New UK Converters for
Converters I Synchrotron Different
Source Machines
17:30 E. Carroll I. Benfatto T R. Walker H.-J. Eckoldt
17:30
TIME FOR DISCUSSIONS TIME FOR DISCUSSIONS
18:30
18:30 RECEPTION
20:00 DINNER DINNER DINNER DINNER DINNER BANQUET
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Contents
Foreword
D.Brandt ................................................................................ v
Powersuppliesandaccelerators
N.Marks ................................................................................. 1
Powerconverters: definitions,classificationandconvertertopologies
F.Bordry ................................................................................ 13
High-poweractivedevices
E.Carroll ............................................................................... 43
Passivecomponentsusedinpowerconverters
A.Rufer,M.Veenstra,P.Barrade .......................................................... 57
Methodsforasystematicanalysisofpowerconverters
C.DeAlmeidaMartins .................................................................. 103
Rectifiers
R.Visintini ............................................................................. 133
Switched-modeconverters(onequadrant)
Ph.Barrade ............................................................................ 185
Four-quadrantpowerconverterbasedonoutputlinearstage
Y.Thurel ............................................................................... 209
PowerconvertersforITER
I.Benfatto .............................................................................. 231
Powerconvertersforcyclingaccelerators
N.Marks ............................................................................... 249
Regulationtheory: reviewanddigitalregulation
F.Bordry ............................................................................... 275
High-precisionmeasurements
G.Fernqvist ............................................................................ 299
ADCstoDACs(analog-to-digitalanddigital-to-analogconverters)
J.Pickering ............................................................................ 311
Protection,interlocksanddiagnostics
S.A.Griffiths,G.Charnley,C.WhiteandJ.E.Theed ........................................ 327
Electricalnetworkandpowerconverters
H.U.Boksberger ........................................................................ 347
Simulationtools
F.Jenni ................................................................................ 363
Differentpowersuppliesfordifferentmachines
H.-J.Eckoldt ........................................................................... 385
Futurechallenges
N.Marks ............................................................................... 405
ListofParticipants ........................................................................ 423
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Power supplies and accelerators
N. Marks
CCLRC Daresbury Laboratory, Warrington, UK
Abstract
The paper is intended to provide an introduction to the magnets employed in
a circular particle accelerator to bend and steer the charged-particle beam.
These are the principal loads that power converter engineers will encounter
and the basic concepts of the accelerator lattice are presented, without
assuming any prior knowledge. The interface with the power converters is
examined and the need to optimize the supply and the load together is
highlighted.
1 Introduction
The magnets used in circular particle accelerators cover a wide range of field distributions and
technologies. By far the most common are the lattice magnets, comprising dipoles, quadrupoles, and
sextupoles, which control the beam direction and envelope. In most accelerators these are room-
temperature, resistive magnets but the use of superconducting technology is becoming standard for the
largest, most demanding hadron accelerators. In all cases, however, the magnetic flux densities in
lattice magnets are generated by current carry coils; hence the need for power converters. This is not
the case for most ‘insertion devices’ (wigglers and undulators) used in synchrotron sources, which,
increasingly, now make use of permanent magnet technology; these types of magnet are therefore not
treated in this presentation.
The paper concentrates on resistive magnets, where the field distribution is principally
determined by the precision pole shape rather than current distribution in the coils. The reverse is true
for superconducting magnets, where current distribution plays a vital role. Equally, the typical
impedance levels used for superconducting assemblies are usually much lower than those encountered
in resistive magnets—the superconducting coils operate at much higher current densities.
Notwithstanding, the basic field distributions and the need to match power converter to magnet are
common to both types of magnets, so it is intended that this introduction to resistive magnet
technology and the optimization of the load/converter interface will be of value over a range of
applications.
2 Types of magnets in particle accelerators
2.1 The magnet lattice
The lattice magnets control the direction and size of the circulating beam:
– dipoles bend and steer the beams;
– quadrupoles focus the beams;
– sextupoles control the focusing of off-momentum particles—( the ‘chromaticity’ of the beam).
Together they make up the ‘lattice’ of the accelerator.
Figure 1 shows one twenty-fourth of the separated function lattice of ‘Diamond’, the 3 GeV
synchrotron source currently under construction in the UK. This is a highly developed lattice,
1
N. MARKS
containing 48 dipoles, 240 quadrupoles and 168 sextupoles, this degree of complexity being required
to provide flexibility in beam dimensions at the many experimental stations located around the
periphery of the facility.
Cell Layout
F-Quad F-Sext
D-Quad D-Sext
Dipole

Fig. 1: One twenty-fourth of the lattice of the Diamond synchrotron source; the large mechanical
assemblies at each end of the sector are ‘insertion devices’, which are distinct from lattice
magnets
2.2 Dipole magnets
2.2.1 Dipole geometry
A number of different geometric arrangements for the steel yoke and excitation coils (usually copper
with glass insulation) are used for lattice dipole magnets. The most common is the ‘C core’ dipole; the
cross-section of such a magnet is shown in Fig. 2.

Fig. 2: Cross-section of the ‘C core’ dipole bending magnet of the Diamond synchrotron source;
the vacuum vessel that contains the circulating electron beam is placed between the jaws of the
poles on the right of the magnet; the excitation coils are placed immediately above and below this
gap

2