Presentazione di PowerPoint

1
Power Converters for Future LHC
Experiments Apollo collaboration, funded by
I.N.F.N. Italy M. Alderighi(1,6), M.
Citterio(1,), S. Latorre(1), M. Riva(1,8), M.
Bernardoni(3,10), P. Cova (3,10), N.
Delmonte(3,10), A. Lanza(3), R. Menozzi(10), A.
Costabeber(2,9), A. Paccagnella (2,9), P.
Tenti(2,9), F. Sichirollo(2,9), G. Spiazzi(2,9),
M. Stellini(2,9), S. Baccaro(4,5), F.
Iannuzzo(4,7), A. Sanseverino(4,7), G.
Busatto(7), V. De Luca(7) (1) INFN Milano, (2)
INFN Padova, (3) INFN Pavia, (4) INFN Roma, (5)
ENEA UTTMAT, (6) INAF, (7) University of Cassino,
(8) Università degli Studi di Milano, (9)
University of Padova, (10) University of Parma,
() Presenter
The increase of the radiation background and the
requirements of new front-end electronics will
characterize the future LHC luminosity upgrade
and are incompatible with the current capability
of the distribution systems in use. An isolated
dc-dc resonant main converter (MC) and Point of
Load (POL) converters deployed at the very heart
of the experimental setup have been proposed to
face these new requirements. The MC, with
redundancy characteristic, supplies an
intermediate medium voltage bus which
distributes the voltage to the electronic
front-end and read-out boards, where non-isolated
Point of Load converters are implemented for
precise voltage adaptation and regulation. In
Large Hadrons Collider applications the design of
these electronics equipments, which must cope
with a highly hostile environment in terms of
high radiation and a background magnetic field up
to 2 Tesla, opens a severe tolerance issue for
the integration technology.
Proposed Power Supply Distribution System
Test case ATLAS Liquid Argon (LAr) Calorimeters

• Characteristics
• Main isolated converter with N1 redundancy
• High DC bus voltage (12V or other)
• Distributed Non-Isolated Point of Load Converters
  (niPOL) with high step-down ratio

48V?5
Non-Isolated PoL Converter Interleaved Buck with
Voltage Divider - IBVD
12V?5

• Characteristics
• Zero voltage switch turn on
• High step-down ratio
• Reduced switch voltage stress (Uin/2)
• Interleaved operation with automatic current
  sharing and ripple cancellation

Main converter

• 3 modules 1.5 kW each
• redundancy n1
• current sharing
• interleaved operations
• Switch In Line Converter - SILC
• phase shift operation
• ZVS transitions
• high efficiency
• reduced switch voltage stress
• high frequency capability

IBVD
Specifications Input voltage Ug 12 V Output
voltage Uo 2.5 V Output current Io
3A Operating frequency fs 1 MHz 350 nH air
core inductors Dimensions L 6cm, W 4.2cm
Small signal dynamics
EPC GaN MOSFET
33 cm
X-rays for checking the solder quality
Air bubbles
Measured DUT voltage and current during switching
intervals
7 cm
Rshunt 85 mW
Output voltage response to a load step change
(25 A ? 37 A)
Planar transformer
Turn on interval _at_ Vcc 100V, IDS 0A
Turn off interval _at_ Vcc 100V, IDS 5A
Main converter module thermal design

• 3D Finite Element Model (FEM)
• FE modeling of the main heating components
• Input power MOSFETs
• Output diodes
• Inductor
• Planar transformer
• Thermal measurements 1
• Thermal characterization on single components, to
  validate models
• Thermal design
• Designed advanced solutions to improve heat
  exchange
• Power MOSFETs mounted on IMS board
• ISOTOP diode isolated package directly mounted
  on baseplate
• Copper thermal layers for transformer core
  cooling
• Silicone gap filler for transformer windings
  cooling
• Thermal simulation and measurements 2
• Preliminary thermal measurements on the air
  cooled whole converter

Turn ratios 10102 4 units connected in parallel
Transformer behavior in stationary Magnetic Field
orange primary winding voltage blue     
secondary winding voltagemagenta  primary
winding current green snubber current
(proportional to the switching losses).
Measurement point ?TSIM C ?TMIS C e
Transformer core 55 51 8
Primariy windings 67 73 8
Secondary windings 75 70 7
ISOTOP diodes 47 49 4
Inductor 23 24 4
Bstat. 789 Gauss
Bstat. 2591 Gauss
Specific activities are addressed to obtain a
ferromagnetic nucleus able to produce high
magnetic field with limited current stimulations.
The base elements consist in a mixture of Fe and
Si powders blended in precise ratio (percentage
of organic additives, and blending methodology
are key points) in order to make a ferromagnetic
compound injection moulded in test sample.

• Final requirements
• Main converter output power 3x1 kW
• Case dimensions 150 x 402 x 285 mm3
• Max case temperature 18C
• Water cooling system
• delivery 1.9 l/min
• ?p 350 mbar
• Tinlet 18C
• Toutlet 25C