ARL/Northeastern University Progress Report / Visit to ARL

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ARL/Northeastern UniversityProgress Report /
Visit to ARL
Project 1 Field Sustainment Power Conditioning
(Wes Tipton) Project 2 High Temperature DC/DC
Converter (Damian Urciuoli)

• Brad Lehman (PI)
• Visiting Grad Students Rosa Ciprian, Florent
  Boico, Jennifer Savage
• Dept. Elect. Comp. Engin.
• Northeastern University
• Lehman_at_ece.neu.edu
• [phone]
• Tuesday May 31, 2005

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ARL/Northeastern UniversityProgress Report /
Visit to ARL
Have we aged since October 27, 2004?
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Overview of Projects

• Field Sustainment Power Conditioning
• Awarded Q4FY03
• NU approximately 80k/year
• Model, design and build solar battery chargers
  for NiMH batteries
• Test solar arrays and batteries
• ARL funding for 1 grad student, but usually 2-3
  work on the project (student projects, matching
  internal funds, etc.) Florent Boico, Jennifer
  Savage, Dung Nguyen
• Clark Atlanta University approximately 20k/year
  for simulation support
• High Temperature DC/DC Converters
• Awarded Q4FY04 at approximately 190k/year
• Funded 2 students, but 3 grad students are
  actually working on project (matching funds)
  Rosa Ciprian, Ting Qian, Wei Song
• Results to date include
• Prototype half-bridge copper board prototype and
  pcb design for 2-stacked board design, 1/2 brick
  size (on order) of 2.4 x 2.3x 1
• Simulations in Spice evaluations of various
  topologies
• Thermal simulations CFD and simplified
  electro-thermal models
• Invention of new two-stage topology for high
  voltage applications

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Field Sustainment Power Conditioning

• Technical Challenges
• Problems reported by CERDEC of damaged
  batteries when charging with portable solar
  arrays
• Basic research charging batteries in
  (relatively) high temperature with changing power
  source has not been investigated before
• Applied research developing and building
  prototype chargers.

Charger
Major Accomplishments

• Explained performance degradation of batteries
  when charging with solar array is due to high
  temperature overcharging
• Designed, built, and tested solar array NiMH
  battery charger control algorithms
• -- New temperature differential charge
  control algorithm developed in 2005
• -- Max. Power Point Tracker for charger (2005)
• -- Preliminary patent disclosure (2005)
• 2005 IEEE PESC paper to appear in June.
• Note 2005 Renewal funding received 5 months
  late delayed research in solar charging of
  Li-ion batteries.

Team Members Brad Lehman (NEU), Khalil Shujaee
(CAU), Wes Tipton, (ARL)

• Project Objective/Description
• Explain reasons for Reduced battery capacity,
  damaged batteries and reduced life-cycle
• Design, develop, and test solar battery charge
  controllers that Fully charge batteries,
  maintain battery capacity and life-cycle.

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High Temperature DC/DC Converter
Prototype half-bridge

• Project Objective/Description
• Design a high power density converter with target
  size of ¼ brick (perhaps a little taller if place
  on two stacked boards)
• Vin 600 V Vout 28V, 1 load regulation
• Year 1 Ambient temperature -10oC 85oC

Primary Turns 40 47 52
Secondary Turns 6 7 7
Vi(V) 618 623 614
Ii(A) 0.178 0.177 0.179
Vo(V) 28 28 28
Io(A) 3.5 3.506 3.506
Efficiency() 89.1 89.0 89.3

• Technical Challenges
• High power density desired but
• Large number transformer turns ratio
• 85 degree Celsius Year 1 with no air flow
  (increase to above 100 deg. Celsius in Y2)
• 3000V input-output isolation
• Primary switches are the source of heat/power
  loss
• Synchronous Rectification?

Some Year 1 Accomplishments

• Simulations
• --- Spice analysis of candidate topologies
  half-bridge, asymmetrical half bridge, invented
  topologies,
• --- Thermal CFD and simplified steady state
  electro-thermal models
• Prototype Half-bridge
• --- Open loop power efficiency above 89
• --- Gerber files for ½ brick, two stacked board
  prototype have been shipped out for fabrication
• Invented new two stage isolated DC-DC converter
  for high-voltage applications

Team Members Brad Lehman, Northeastern
University (NEU), Damian Urciuoli, (ARL)