Transcript Army Transition To 42-V Vehicular Electrical Power System Mr. Barry Gilbert*, Dr.

Army Transition To 42-V Vehicular
Electrical Power System
Mr. Barry Gilbert*, Dr. M. Abul Masrur**, Mr. John Monroe**, Mr.
Rakesh Patel**, Mr. Mike Smith*
* DCS Corporation ** U.S. Army TACOM
NDIA 3rd Annual Intelligent Vehicle Systems Symposium
June 9 – 12, 2003
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Objectives of this presentation
The purpose of this paper is to show the:
• Advantages in transitioning to a dual 28/42V
electrical system that will overcome the
current 28V drawbacks
• Need to rapidly develop a new power system
capable of supporting integration of new
technologies.
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Electrical System Trends
• Both military and commercial vehicles electrical power
needs have increased substantially over the past years.
• The automotive industry is transitioning to a 42V
electrical system that dramatically increases available
power for technical advances with less space and
weight in the existing 12V vehicles.
• Military vehicles should follow the same trend
• The current 28V system meets only 40% of the Future
Combat System (FCS) needs for power generation,
energy storage and power distribution.
• A prototype 28/42V military vehicle does not yet exist
and it is imperative that a prototype vehicle electrical
system be investigated
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Background – Voltage Evolution
Evolution of voltage for commercial and military
vehicles
Commercial
– 6 volts (7 v charging) to 12 volts (14 v charging) in the
1950’s for passenger vehicles
– 12 volts (14 v charging) to 24 volts (28 v charging) since
the 1950’s for trucks
– On the way from 12 volts (14 v charging) to 36 volts (42 v
charging) since the 2002 for passenger vehicle
Military
– Followed commercial vehicles until the late 1940’s
– 24 v (28 v charging) used in most military since the late
1940’s
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Power Needs
• 3 Kw or 3.5 Kw (with an
anticipated 5 Kw or higher later
on) in commercial automobiles in
the near future.
• About 5 Kw (with an
anticipated 15 Kw) in military
vehicles in the near future.
* The above and other pictures in this presentation are from various open literature and open websites of non-govt. and govt. sources.
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ELECTRICAL POWER SYSTEM REQUIREMENTS
FOR MILITARY VEHICLES
• LAV -- Alternator 28 v dc,
245/280 amps ( 7.5 Kw)
• HMMWV – Alternator, 28 v
dc, appx. 100 amps in a
particular variant ( 2.8 Kw)
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ELECTRICAL POWER SYSTEM REQUIREMENTS
FOR MILITARY VEHICLES
• FMTV -- Alternator, 14/28
dual volt dc, appx. 100 amps
in a particular variant (200
amps option) ( 2.8 Kw)
• Abrams Tank – 28 v dc,
650 amps ( 18 Kw)
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ELECTRICAL POWER SYSTEM REQUIREMENTS
FOR MILITARY VEHICLES
• UGV – Similar to above
depending on the platform
chosen
• Robots – As low as 30 watts to
1500 watts @ 12 v or 24 v,
Current: about 3 amps to 100
amps, depending on the
voltage.
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Needs in Military
• Improved mission effectiveness implying
– Increased silent watch time
– Managed dynamic power allocation, enabled use of advanced
technologies to maximize combat performance, and reduced
logistical footprint.
• More electrical power will be required so the latest technologies
can be incorporated
• Primary 28/42V transition objectives become:
– Increase available power and energy storage,
– Reduce fuel consumption,
– Implement X-by-wire (X represents steer, brake, suspension,
engine management, etc.)
– Replace bulky mechanical components with smart and lighter
electrical components, including reduction of wiring harness
weight
– Improve mission effectiveness
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Needs in Military
- Belt-less engine operation for most components (safety
and reliability)
- Better design packaging (components do not have to be
located on the belt system).
- A prototype 28/42V military vehicle does not yet exist
and it is imperative that a prototype vehicle design and
build be started to demonstrate the advantages of
transitioning to a higher voltage system.
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Typical 42/28 dual-voltage architecture
AC
42-volt
36-volt
36-volt
starter
battery
loads
24-volt
24-volt
battery
loads
DC
42 to 28
volt
conversion
system
(DC/DC
converter)
Alternator
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Military Vehicle Power Demand Versus Time Trend
 Hybrid Engine
 High Power Weapons
 High Power Protection
Power
Demand
 Electronic Architecture
 Digital Electronics
 Advanced Sensors
 Fire Control and NBC
 Digital C2 and SA
 Silent Watch
 Drive-by-Wire
 Automotive Loads
 Voice Radios
 Analog Electronics
First Generation
Systems
Time
Legacy/Interim/Small
Robotic Systems
Objective force
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Components affected by voltage shift to 42 v
(commercial vehicles)
• Cooling fan (13 A)
• Starter (few hundred amps for
short duration amperage
draw)
• Alternator
• A/C blower motor (22 A)
• Windows motor (8 amps )
• Vacuum pump (7 amps)
• Power seat (7 amps)
• Wiper (4 amps)
Less affected -• Washer (3 amps)
• Idle speed (0.6 amps)
• Door lock (1.5 amps)
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Practical issues
• Beyond certain size, can’t reduce motor winding
gauge due to manufacturing constraints
• Similarly, in the wiring harness only the wires
carrying > 3 amps can be reduced in size
• Implies that only 34% of the wiring harness will
be benefited by the introduction of 42-volt system
(24% total copper savings), compared to 14 volts.
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Components affected by voltage shift to 42 v
(military vehicles)
More affected • Starter , alternator , climate control systems,
• Thermal power unit (20 amps)
• Motors for certain armor systems (4 amps)
• Cooling fan
• Washer (3 amps)
Less affected -• Idle speed motor (0.6 amps)
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Benefit claim and payoff for transitioning to a
28/42V.
Benefit Claim
Power/Energy Management
Meet Force Transform Objective
Payoff
• Better performance to improve mission
effectiveness such as, increased silent watch time
• Autonomous control of vehicle power distribution
based on the vehicle state and mode
• Permit graceful degradation of loads
Provide something better than what currently exists
Increased power
• Less electrical distribution loss due to better
efficiencies
• Permit support of new electrical equipments for
changing mission needs
• Improve cold start requirements
Lower space and weight claim (better packaging)
• Permit addition of new electrical equipments for
changing mission needs
• Cable weight reduction on circuits carrying >3 amps.
More efficient processes
• Reduced fuel consumption (Army Key Performance
Parameter)
• Lower crew workload to reduce personnel fatigue for
longer-duration missions.
Smart electrical components
• Replacement of bulky and inefficient
mechanical/hydraulic systems to improve
efficiencies and reliability
• Reduced parasitic loss
• Current control circuitry for power management and
built in test for diagnostics/maintenance
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Benefit claim and payoff for transitioning to a
28/42V -- continued
Benefit Claim
Payoff
Lower life cycle costs
Lower Unit of Action Operation and Maintenance
(O&M) costs through greater reliability and lower
maintenance
Incorporation of latest technologies
• Reduces the prospect of technical obsolescence
• Increases service life
• Convenience and comfort features available to
reduce crew work load and fatigue
Dual voltage
• Backward compatible with 28V legacy systems
• Permit introduction of selected advanced
technologies in legacy systems
Quieter operation
Reduced acoustical noise signature for improved
survivability
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Benefits to components for transitioning to a
28/42V electrical system.
Component
Benefit
Integrated Starter Generator (ISG)
• Optimized design by consolidating starter and
generator in a single unit provides space claim
advantage
• Allows engine cut off during slow down
• Short delay in engine restart with non-perceivable
lag Implementation of brake regeneration possible
when ISG placed in line with the crankshaft
• Can add power to the system during high torque
demands
• Potential fuel consumption reduction by 6-12 %, as
demonstrated in the automotive industry
Source Power Converter
• More compact design at 42V
• Allows backward compatibility with 28V legacy
systems
Constant power mechanical loads driven by
electricity
• More efficient at 42V
• Advanced brushless dc and switched reluctance
motor drive technology can be implemented
Higher power generator/alternator
• Compact design due to increase in voltage from
28V to 42V
• Better efficiency at 42V with optimized magnetics
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Benefits to components for transitioning to a
28/42V electrical system -- continued
Component
Electronic power modules
Benefit
Compact size due to change from 28V to 42V.
Pump and fan loads
• Operate on demand
• Reduces/eliminates parasitic operation found in
belt driven implementation
Electric valves
• Provides variable timing options not available with
mechanical implementation
• Precise control and ability to monitor operation
Electrical conductors
• Smaller cross section wire leading to lighter cable
harnesses
• Space claim advantage due to smaller size
Batteries
• Energy density increase of 80 percent
• Life increase of 2x
• Status and state of charge feedback
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JUSTIFICATION OF 42 V SYSTEM
Advantages
• Overall gain in electrical system efficiency (even without new
functionalities, e.g. X-by-Wire, ISG etc.)
• Packaging advantages due to the introduction of new
functionalities by replacing mechanical elements
• 42 v system leads to improved packaging compared to 14 or 28
v
Issues
• Higher lamp filament voltage for lighting can be overcome by
use of LED technology
• Load dump and high voltage transients
• Arcing due to higher voltage
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Transition Plan
The path to 42V transformation includes:
•
•
•
•
•
•
Compatibility with current/emerging industry practices
Compatibility with legacy vehicles
Use of emerging standards such as, 42V PowerNet
Compatibility with Army fielding process
Endorsement by Army users and leading industry players
Acceptance as formal Army standard.
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Transition Plan -- continued
The existing Advanced Mobile Power System (AMPS) STO
is focused towards the development of the configurable
power system, which is :
•
•
Capable of supporting electrical power and power
management requirements to integrate Vetronics, C4ISR
(Command,
Control,
Communications,
Computers,
Intelligence, Surveillance and Reconnaissance, and
embedded simulation capabilities into FCS platforms,
including robotic Unmanned Ground Vehicles (UGV).
The success of the AMPS STO can easily be extrapolated to
any future military vehicular platform as well.
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Summary
•
The current 28V vehicle electrical system is inefficient, bulky, and less cost
effective for the rapidly increasing power demands caused by new vehicle
electrical loads such as, high power directed energy weapons, self protection
(countermeasures) computers, multimedia, displays, communications, drive
by wire, etc.
•
Mission needs are changing and requiring greater flexibility of vehicles.
•
As time passes, new technologies must be introduced to improve mission
effectiveness.
•
The added features in military vehicles have exhausted the operating margin
in the current 28V electrical system.
•
The military vehicles must follow the automotive industry to a higher voltage
electrical system, such as 42V
•
The payoff is significant in terms of flexibility, improved mission effectiveness,
and decreased logistics burden.
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CONCLUSIONS
•
•
•
•
•
Beneficial for the military to embrace and phase in a 42-volt (single-voltage)
electrical system architecture by starting with a dual 28/42 volt system.
Dual 14/42-volt for commercial and 28/42 volt for military will benefit from better
packaging, weight reduction, and improved efficiency, even if X-by-wire or ISG is
not incorporated.
Fuel economy will be improved by integrating components such as, integrated
starter alternator (hybrid operation), electrical brake and steering systems, which
are difficult to package using the existing 14 and 28 volt technologies.
Fuel economy will also result from several improvements working together, e.g.
reduced size and weight of wiring harness, brake regeneration, integrated starter
generator (hybrid operation), parasitic loss reduction, etc.
In terms of lamps use of new technologies like incandescent HID, LED’s, or PWM
technology based lamps will be beneficial.
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