Transcript ATLAS Upgrade week - PRIN2007 and Apollo

R&D on power supply distribution systems for
calorimeters and muon detectors at the LHC phase II
Status and future perspectives
Research team:
M. Alderighi(1,^), S. Baccaro(2,^), F. Belloni(3), M. Bernardoni(5), G. Busatto(6), S.
Buso(7), M. Citterio(4), P. Cova(5), N. Delmonte(5), F. Iannuzzo(6,10), A. Lanza(9,*), P.
Maranesi(3), R. Menozzi(5), C. Meroni(4), A. Paccagnella(7,8,^), A. Porzio(6), M.
Riva(3,4), G. Spiazzi(7), P. Tenti(7), F. Velardi(6)
^ Not partecipating to the PRIN2007 activity
* Speaker
1 – INAF/IASF and INFN Milano, Italy; 2 – ENEA Casaccia and INFN Roma,
Italy; 3 – University of Milano, Italy; 4 – INFN Milano, Italy; 5 – University of
Parma, Italy; 6 – University of Cassino, Italy; 7 – University of Padova, Italy; 8
– INFN Padova, Italy; 9 – INFN Pavia, Italy; 10 – INFN Pisa, Italy
Research co-funded by Ministero dell’Istruzione, dell’Universita’ e della
Ricerca (MIUR) and INFN, under the PRIN2007 programme
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Goals of the collaboration
 Investigating the performance of active components available
on the market in a sLHC-like environment, selecting the ones
suited for the designed DC/DC converters
 Designing distribution architectures and DC/DC converters
able to cope with the tight requirements in terms of environment
(radiation and B field), electrical/mechanical parameters
(voltages, currents, dimensions) and thermal management usually
found in calorimeters and muon detectors
 Prototyping the designed converters and implementing all
state-of-the art techniques in order to meet the thermal
requirements
 Testing the prototypes on the bench and in radiation and Bfield environments, modifying their design as a function of the
results
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Summary of activity in the past two years
Developed under the PRIN2007 programme
 The R&D of the years 2009 and 2010 was devoted to the development of a PS
distribution system able to cope with the sLHC specifications of the LAr
calorimeters, because of the extremely high values of the required radiation
tolerance:
Several 30V and 200V power MOSFET from different manufacturers tested up to
10kGy at the ENEA Casaccia 60Co g-ray source, average energy 1.25MeV. Heavy ions
irradiations were also performed at the INFN Laboratori Nazionali del Sud, Catania
 The chosen distribution system was the Intermediate Bus Architecture (IBA), based
on a Main Converter (MC) to reduce the voltage from 280VDC to 12VDC, and several
Point of Load (PoL) converters to distribute lower voltages to the electronics
 The MC, based on the above architecture, was designed and a prototype partially
realized and bench tested
 In order to meet the B-field specifications of the MC, a planar primary transformer
was designed and a prototype was realized and implemented in the MC prototype
 The thermal performance of both the MC and the planar transformer was evaluated
by FEM and tested by IR measurements
 Two PoL converters were designed and prototypes realized and bench tested
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Radiation tests of power MOSFETs (Univ. of Cassino)
 Tests performed at 10Gy/h up to 10kGy
 PCB holder capable of hosting up to 88 devices (see picture at
the bottom)
 Four different polarizations used for each device on the same
holder (see here)
 11 30V and 9 200V devices of various manufacturers tested
with 7 samples each
 Post-irradiation annealing performed, T = 100 °C, bias
applied, 1 week long (ESA/SSC 22900)
 Results of Vth for the best 30V and 200V devices are shown
here. The 10kGy limit can be reached with some precautions
 No increase of the oxide leakage current was observed during
the irradiation (shown here for the best 30V device)
30V
200V
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Distribution architectures
Chosen architecture – IBA with
one isolated MC, reducing the
280 VDC
voltage from 280VDC to
12VDC, and several nonisolated PoL (niPoL) on boards
Card #3
Main
Main
Converter
Converter
12 VDC
(or other
intermediate
DC voltage)
Crate
niPOL
POL
Card #2
Converter
niPOL
niPOL
Converter
Card
#1POL POL
Converter
niPOL
niPOLPOL
Converter
niPOL POL
Converter
POL
Converter
niPOL
niPOLPOL
Converter
POL
Converter
niPOL
POL
Converter
Alternative solution – Higher output voltage from MC
Actual present architecture of LAr
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Main Converter 1 (Univ. of Milano)
7 cm
It consists of three equal modules, each one
delivering 1.5kW.
Redundancy n+1 is adopted. The three modules are
connected in parallel to provide power up to 3kW.
In case of failure of one module, the remaining two
can deliver the same power.
33 cm
Design is based on the Switch-In-Line Converter (SILC)
topology (see below), because of the reduced voltage stress
across MOSFETs (reducing their sensitivity to radiation) and
zero-voltage commutation at switch turn-on.
A 20W auxiliary converter is included in each module, in order
to supply drivers and supervisors at the startup.
Main converter module specifications
+
C4
Input voltage = 280 V
Output voltage (main) = 12 V
Maximum supplied power (main) = 1.5 kW
Switching frequency (main) = 100 kHz
C3+
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T1
iL
Q4
Q3
T3
Q2
T4
Co
+
Vout
-
Vin
C2+
Output voltage (aux) = 5V
Maximum supplied power (aux) = 20 W
L
C1+
iT2
T2
Q1
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Primary planar transformer layout is composed of 4
units connected in parallel, each one made of a 22
layers PCB. The turn ratio is 10:2.
The magnetic core is made of Cool-Mu material.
One 1.5kW module equipped with the planar
transformer was produced (see pictures).
First bench measurements are reported below.
Global efficiency is included between 80% and 90%
for the full power range (no B).
Transient response at full load is also shown.
22 layers
4.71 mm
Main Converter 2 (Univ. of Milano)
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Efficiency
0.9
0.8
0.7
0.6
0.5
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Output power [kW]
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Thermal management (Univ. of Parma)
MC simulated with 3D Finite Element Model under the conditions:
• Output power = 1200 W
• Natural air convection on top and vertical surfaces
• Forced convection plate-thin heat sink at the bottom
• Ambient temperature = 27°C
• Total power dissipation at given conditions 220 W
Simulation results are shown below, compared with IR
measurements on the real module.
Case with three modules inside, of dimensions 150 x 402 x 285 mm3,
2 mm thick stainless steel, was thermally simulated, under the
following conditions:
• MC output power = 3 kW • Max case temperature =18°C
• Liquid cooling system delivery = 1.9 l/min • Δp = 350 mbar
• Tinlet= 18°C
• Toutlet≤ 25°C. Results are shown below for three
Module
working modules and two working modules (one fault)
simulated
results
Module IR
measurements
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niPoL converters (Univ. of Padova)
S1
Chosen topology: Interleaved Buck with Voltage Divider (IBVD): U
• Zero voltage switch turn-on • High step-down ratio
• Reduced switch voltage stress (Vin/2)
• Interleaved operation with automatic current sharing and
ripple cancellation
High current PoL 7 x 3.5 cm2:
Vin = 12V
Low current PoL 6 x 4.3 cm2 (in
collaboration with Faccio’s team): Vout = 2V
Iout = 20A
Vin = 12V
Operating frequency = 280 kHz
Vout = 2.5V
Ferrite core inductors (2.2 mH)
Iout = 3A
Prototype and measured
Operating frequency = 1MHz
efficiency shown here
Air core inductors (350 nH)
Prototype shown below with measured
efficiency compared with a single buck
i1
S2
+
in
L1
+
S4
Co
UC1
-
C1
L2
Uo
-
i2
S3
Uo = UinD/2 for D < 50%
Efficiency
0.88
0.86
IBVD
0.84
0.82
0.8
0.78
S4
L1
5
10
15
20
Output current [A]
S2
Cin
Co
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S1
C1
S3
L2
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Future perspectives – The Apollo R&D
 From 2011 onward this R&D will be funded by INFN only under the name Apollo
 The Apollo working programme for the next two-three years is the following:
 Testing the radiation hardness of the present devices with protons and neutrons
 Looking for new devices appearing on the market, particularly for new technologies
like the GaN and testing them
 Concluding the construction of a full MC prototype with three modules, a case and
the cooling system, if necessary implementing new cooling techniques like the IMS
 Continuing the thermal simulations and measurements of the MC prototype,
designing its cooling system
 Completing the radiation and B-field tests of the full MC prototype
 Modifying its electrical and mechanical parameters for making it suitable for Muon
chambers
 Designing new PoL converters for use with the Muon chambers in a very high B
field, up to 2T, studying new topologies and adopting new devices
 Characterizing new core materials able to work up to 2T, or as alternative defining
the performance of the best materials available on the market
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