Fk. Bordry AB/PO Academic Training - 27th March 2003 hnological Challenges for the L ower converters for the LH Frédérick BORDRY AB-PO ? I (A) t 11800 20 min -10 A/sec +10 A/sec 2 min several hours 0.1 A/sec 350 A 1 min 350 A pre-injection (1 min - 1 h) 860 A 860 A 500 W 2,2 MW 115 kW
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Fk. Bordry AB/PO Academic Training - 27th March 2003 Technological Challenges for the LHC Power converters for the LHC Frédérick BORDRY AB-PO ? I(A) t.
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Fk. Bordry AB/POAcademic Training - 27th March 2003
Technological Challenges for the LHC
Power converters for the LHCFrédérick BORDRY AB-PO
?I (A)
t
11800
20 min
-10 A/sec
+10 A/sec
2 min
several hours
0.1 A/sec350 A
1 min
350 A
pre-injection (1 min - 1 h)
860 A
860 A
500 W
2,2 MW
115 kW
Fk. Bordry AB/POAcademic Training - 27th March 2003
What’s special about Powering Superconducting Magnets ?What’s special about Powering Superconducting Magnets ?
High Current Large Inductance
No Resistance
Need heavy warm cabling Need to be near to feed point
Difficult and expensive power converter output stage
Large Stored Energy, 1/2 LI2
Need to handle carefully!
Large Time Constant, L/R Boost voltages (high voltage only during the ramps) Difficult control loops
Tendency to quench Need to take special precautions (energy)
Fk. Bordry AB/POAcademic Training - 27th March 2003
• The beams are controlled by:• 1232 SC Main Dipole magnets to bend the beams
• 392 SC Main Quadrupole magnets to focus the beams
• 124 SC Quadrupole / Dipole Insertion magnets (in 196 circuits of ~ 6 kA)
• 6340 SC Corrector magnets (in 1460 circuits 60 to 600A)
• 112 Warm magnets (in 38 circuits 600 to 900A)
• SC RF Cavities to accelerate and stabilize the beam
– All ~8000 magnets need to be powered in a very controlled and precise manner
LHC Large Hadron Collider - What needs powering?LHC Large Hadron Collider - What needs powering?
Fk. Bordry AB/POAcademic Training - 27th March 2003
LHC : 1232 SC Main Dipole magnetsLHC : 1232 SC Main Dipole magnets
One circuit or several circuits ?
Magnet inductance : L = 108 mH
Ltotal=1232 * 0.108 = 133 HRamp: LdI/dt = 1330V
Discharge (quench; 120 A/s): 16kV
Nominal current 11.8 kAStored Energy = 9.3 GJ
Ultimate current = 13kAStored Energy = 11.3 GJ
L/R 50 hours !!!!
Fk. Bordry AB/POAcademic Training - 27th March 2003
Natural segmentation into 8 units as no cryostat in straight sections. Warm cable connections costly in copper , power losses (~30MW) and power
converters Total stored electrical energy in LHC main dipoles is ~10.6 GJ. Discharge in
120 seconds means 16 kV! Only 1/8 of the machine needs to be discharged if one magnet quenches
• No risk of total machine avalanche quench, (false quench detection and provocation)
Earthing of the ring in eight galvanically isolated sectors Less risk of build-up of voltages
• Only two sets of switches for dipoles, one for quads, no timing problems
• Smaller resonant circuit Eight sub-units give easier installation, testing, commissioning and fault
finding for many systems Allows sector-to-sector correction of magnet errors due to different cable,
magnet manufacturers, etc..
Need to track from sector to sector
Why an Electrical Segmentation of the machine?Why an Electrical Segmentation of the machine?
Fk. Bordry AB/POAcademic Training - 27th March 2003
Circuit Nominal Current One Year One day 1/2 hour ResolutionType Current Polarity Accuracy Reproducibility Stability
(A) (ppm of Inominal) (ppm of Inominal) (ppm of Inominal) (ppm of Inominal)
Main Bends, Main Quads 13000 Unipolar ± 50 ± 20 with calibration
± 5 ± 3 1
Fk. Bordry AB/POAcademic Training - 27th March 2003
LHC Power Converters
Number of Converters: 1720Total Current :1860 kA
Steady State Input : 63 MWPeak Input : 86 MW
Number of Converters: 1720Total Current :1860 kA
Steady State Input : 63 MWPeak Input : 86 MW
LEP % LHC
Fk. Bordry AB/POAcademic Training - 27th March 2003
LEP versus LHC for Power ConvertersLEP versus LHC for Power Converters
LEP 200 (up to 110 GeV)Number of converters 900Installed Power = 130 MW (80 MW for the magnets and 50 MW for RF cavities)
Total output current = 115 kAMain dipole current = 4500AMain quadrupole current = 420 A
LHC (up to 7.7 TeV)Number of converters 1720Installed Power = 86 MW (40MW for cryogenics)(70 MW for the magnets and 16 MW for RF cavities)Flat top at 7.7 TeV : 50 MW
Total output current = 1’860 kAMain dipole current = 13’000AMain quadrupole current = 13’000 A
Fk. Bordry AB/POAcademic Training - 27th March 2003
Fk. Bordry AB/POAcademic Training - 27th March 2003
Performances : -High current with high precision (accuracy, reproducibility, stability, resolution) and large dynamics-current range (for 1-quadrant converter: from 1% to 100%)- a lot of 4-quadrant converters (energy from magnets)- tracking : Need to track from sector to sector- voltage ripple and perturbation rejection
The Challenges : The Challenges :
Installation (LEP infrastructure) and Operation: - volume (a lot of converter shall be back-to-back)
- weight (difficult access) => modular approach- radiation for [±60A,±8V] converters- losses extraction : high efficiency, water cooling- EMC : very close to the others equipment ; system approach
Fk. Bordry AB/POAcademic Training - 27th March 2003
UA23 (Ex-LEP Klystron gallery)Now used to house the majority of
machine equipment
such as power converters, magnet protection, injection,
extraction, RF generators, etc.
Very Low Radiation DoseNo Access during “Beam-On”
Access with full power on
Very Low Radiation DoseNo Access during “Beam-On”
Access with full power on
Fk. Bordry AB/POAcademic Training - 27th March 2003
Volume, back-to-back, losses , weight,...No Access during “Beam-On”Access restricted without beam
New Enlargement (RR) for Machine Power Converters around ATLAS and CMS
New Enlargement (RR) for Machine Power Converters around ATLAS and CMS
Constraints :
Fk. Bordry AB/POAcademic Training - 27th March 2003
Radiation Dose1 Gy/year under dipoles
No Access during “Beam-On”Access restricted without beam : Low power
Main Arc TunnelMain Arc Tunnel Orbit Corrector PCs4*[60A,8V]
752 converters
Orbit Corrector PCs4*[60A,8V]
752 converters
High reliability :MTBF : 80 ’000 h1 converter breakdown every 4 daysOne campaign every 2 or 3 months
Fk. Bordry AB/POAcademic Training - 27th March 2003
General approachGeneral approach
• Minimise the number of converter types
• Separate out the subsystems that are desirable/acceptable by industry. Place development and production contracts.
• Design and build prototypes of remaining subsystems. Place production contracts.
• Assume system integration responsibility
• Integration and test at CERN before installation
Fk. Bordry AB/POAcademic Training - 27th March 2003
Special DevelopmentSpecial Development• Converter topologies :
– High current (13kA) and high power (2.5 MW) 2-quadrant converters (main dipoles)
– Switch-mode converters (soft-commutation 20 to 100 kHz)• Parallel subconverters
• 4-quadrant converters (energy management)
• High precision current transducer (DCCT)• Current calibration system• High precision ADC (>20 bits ; )• Control loops :
Other central insertion elementseg. Low Betas, separator dipoles
COLD (<2K) 2.9km
WARM500m
1
5
Cryogenic feed
DC Power feed
3
Oct
ant
DC Power
Main Arc FODO cellscontaining; main dipoles andquadrupoles, chromaticity sextupoles, octupoles, tuning and skew quadrupoles, spool pieces,orbit correctors
Matching section of insertioncontaining; dispersion suppressors,matching section, and electricalfeedbox.2
4 6
8
7LHC27 km Circumference
Courtesy of P.Proudlock
Fk. Bordry AB/POAcademic Training - 27th March 2003
One Sector (1/8) of the LHC MachineOne Sector (1/8) of the LHC Machine
Cryostat containing 154 Main Dipoles
Nominal Current = 11.8kA (For 7 TeV)Ultimate Current = 13kA (For 9 Tesla)23x3x2=138 magnets in the arc
16 magnets in the two dispersion suppressors154 magnets in total
Ltotal = 0.108 H x 154 16.6 H(LHC sector 1.2GJ at 11.8kA, 1.4 GJ at 13kA!)(HERA ~ 480 MJ)(Tevatron ~ 300 MJ)Charging voltage= 16.6 Hx10A/sec= ±166V (2.2MW)
0 mins
Time Constant = 23000 seconds (6 hours 23 minutes)
Fk. Bordry AB/POAcademic Training - 27th March 2003
LHC power convertersLHC power converters
A- Elementary module [3.25 kA, 18V], [2kA,8V] : (~120) (~700)
Switch Mode Converter (25-40 kHz, soft commutation)Modular approach : 4.0 kA (28) , 6.0 kA (160) , 8.0 kA (8) , 13 kA (24)Redundancy; small volume and weight
Fk. Bordry AB/POAcademic Training - 27th March 2003
Class1 DCCTs (13kA)Class1 DCCTs (13kA)
- Highest performance - state of the art- Separate Head and electronics chassis 19” rack mounting.- Fitted with Calibration Windings- Temperature-controlled environment in the Accelerator.- Full testing and calibration at CERN on the 20kA Test Bed.
- Highest performance - state of the art- Separate Head and electronics chassis 19” rack mounting.- Fitted with Calibration Windings- Temperature-controlled environment in the Accelerator.- Full testing and calibration at CERN on the 20kA Test Bed.
Fk. Bordry AB/POAcademic Training - 27th March 2003
4kA to 8kA DCCTs
600A DCCTs
120A DCCTs
Fk. Bordry AB/POAcademic Training - 27th March 2003
Main Dipole Current CycleMain Dipole Current Cycle
I
t
11500 A
20 min
-10 A/sec(~20 mins)
+10 A/sec(~25 mins)
3-5 mins
several hours(~24 hrs)
0.1 A/sec350 A
1 min
350 A
pre-injection(0-1 hr)
740 A
740 A
500 W
2.2 MW
115 kW
InjectionPlateau
Acceleration
CoastDumpBeam
Fk. Bordry AB/POAcademic Training - 27th March 2003
One Sector (1/8) of the LHC MachineOne Sector (1/8) of the LHC Machine
Total inductance = 16.6H. Total stored energy = 1.2GJ
Current source Power Converter13kA, 10V flat top, ± 180V boostTime Constant = 23000 seconds (6 hours 23 minutes)
EVENPOINTS
2x Energy extraction systems.Maximum rate of discharge = 120A/sec.