1. Evaluation and testing of advanced low-voltage power supplies
12th Workshop on Electronics for LHC and Future Experiments
25-29 September 2006, Valencia, Spain
Bruno Allongue, CERN, PH-ESS
September 27, 2006

2. Agenda Introduction Equipment evaluated Measurements
Corrective actions
Conclusions
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12th Workshop on Electronics for LHC and Future Experiments

3. Background Low-voltage detector power supplies
Low-noise, high-efficiency
Switching technology for efficiency and low-volume
Installation close to the detectors
To avoid distribution over long cables (~120m)
Installation close to the detector implies
Significant stray magnetic fields (ex. CMS)
< 1.8 kGauss
Radiation (ex. ATLAS TRT)
TID - 140Gy over 10 years
Neutrons MeV equivalent neutrons/cm2 over 10 years
Protons - 2*1011 >20MeV protons/cm2 over 10 years
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12th Workshop on Electronics for LHC and Future Experiments

4. Typical topology for switching power supply
Design principle
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12th Workshop on Electronics for LHC and Future Experiments
Typical topology for switching power supply

5. Proof of concept
Work done over several years by CERN and industry to identify potential problems in typical low-voltage power supply architectures
Magnetic field tolerance
“Classical” soft-iron screening
Novel technology – high permeability toroidal transformers
Radiation tolerance
Opto-couplers
Weak components identified
Power transistors
Need for very conservative under-rating
Efficient cooling
Direct water cooling
Air cooling
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12th Workshop on Electronics for LHC and Future Experiments

6. Equipment evaluated
The proof-of-concept process was followed at the end of 2005 by a formal invitation to tender from CERN on behalf of a sub-set of LHC experiments’ subdetectors
Tender included
Detailed electrical specifications
Environmental specifications
Magnetic field and radiation tolerance
Remote control functions
OPC server
Two suppliers were selected
Wiener (Germany)
CAEN (Italy)
Both suppliers offered similar architectures
Radiation and magnetic field sensitive elements as far as possible installed outside the hostile area
Control
Active power factor correction
Tolerant power conversion in the hostile area
Sample equipment was evaluated against the tender specification
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12th Workshop on Electronics for LHC and Future Experiments

7. Radiation & magnetic field tolerance 3. “Maraton” 12ch 50A DC-DC (3kW)
Wiener “Maraton”
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Radiation & magnetic field tolerance
Water cooled μP
230VAC, single phase
1. AC-DC (w. PFC)
3. “Maraton” 12ch 50A DC-DC (3kW)
385VDC
2. Control & monitoring
12th Workshop on Electronics for LHC and Future Experiments μP
Ethernet
OPC Server

8. Radiation & magnetic field tolerance
CAEN “EASY”
Air cooled
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400VAC, Three-phase μP
3. “EASY A3486
AC/DC” 2ch 48V/40A/2KW
1. Harmonic filter
400VAC
48VDC
2. Control & monitoring
4. “EASY crate" with
“EASY DC/DC ” ex. 12ch 9A/45W μP
12th Workshop on Electronics for LHC and Future Experiments
Ethernet
OPC Server

9. Measurements Electrical Environmental Controls Regulation Efficiency
Static
Dynamic
Efficiency
Noise and ripple
Turn ON and turn OFF
Protections
Overcurrent
Overvoltage
Stability
EMC (Harmonic emissions)
Environmental
Magnetic field tolerance
Radiation tolerance
Controls
Check the OPC server for conformity to specifications (IT/CO)
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12th Workshop on Electronics for LHC and Future Experiments

10. Electrical tests Instrumentation Test set up PC DC output
27 Sep. '06 - ba PC
HP 6050 A
Electronic load
DVM Keithley 2000
Oscilloscope Philips PM 3394
Power analyzer Infratek 106A
DC output
Output characteristics measured by oscilloscope and DVM
Controller
USB or ETHERNET
30m cable length with C=300uF
AC input
DUT
Test set up
12th Workshop on Electronics for LHC and Future Experiments

11. Results (Harmonics emissions)
Wiener Maraton
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12th Workshop on Electronics for LHC and Future Experiments

12. Without harmonics filter
Results (Harmonics emissions)
CAEN EASY
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12th Workshop on Electronics for LHC and Future Experiments
Without harmonics filter
With harmonics filter

13. Environmental categories – two specifications
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Spec A
ALICE
LHCb
ATLAS-TRT
12th Workshop on Electronics for LHC and Future Experiments
Spec B
Radiation is present at a level below 4Gy and MeV equivalent neutrons/cm2 over 10 years, of which approximately 10% are above 20MeV.
Stray magnetic fields are present at a level up to 180mT.
CMS

14. Environmental Magnetic field tolerance Tests at CERN
PH-ESS magnet for components tests (1.8kGauss, 15cm gap)
Bigger magnet (MNP22) for systems tests (8kGauss, 50 cm gap)
Both systems conform to specifications
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12th Workshop on Electronics for LHC and Future Experiments

15. Environmental Radiation Protons at Neutrons at Gammas
PSI – Louvain la Neuve
Small diameter beam (8 – 10 cm)
Focus on components
Uppsala
Large beam
Test large system (e.g. CAEN EASY modules)
Neutrons at
Prospero (1Mev Neutrons reactor)
Gammas
Cassacia (ATLAS Muons)
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12th Workshop on Electronics for LHC and Future Experiments

16. Radiation tolerance Uppsala 27 Sep. '06 - ba
12th Workshop on Electronics for LHC and Future Experiments

17. Radiation tolerance PSI 27 Sep. '06 - ba
12th Workshop on Electronics for LHC and Future Experiments

18. Corrective actions required
Wiener
Change optocouplers (NIEL problem)
Change power transistors due to implementation of PFC
Qualification of components
CAEN
Spikes on reset lines (Transients on optocouplers with hadrons)
Low pass filter implementation
Sensitive components (Amplifiers, EPROM)
Change of components
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12th Workshop on Electronics for LHC and Future Experiments

19. Summary
Qualified radiation and magnetic field tolerant detector power supplies are available to the four LHC experiments from two suppliers
Purchase and support contracts have been set up, production is underway and installation has started
Lessons learned
Qualification of COTS equipment is a very long, costly and painful process
Close collaboration between users, power supply and radiation tolerance specialists at the earliest possible stage is of prime importance to minimize time and cost
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12th Workshop on Electronics for LHC and Future Experiments

20. Acknowledgements F.Anghinolfi (CERN) G.Blanchot (CERN) F.Faccio (CERN)
R.Richter (MPI)
C.Rivetta (SLAC)
PH/ESS colleagues
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12th Workshop on Electronics for LHC and Future Experiments