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Glenn Research CenterCleveland, Ohio 44135

Technical Support PackageHybrid Power Management-Based VehicleArchitecture

NASA Tech BriefsLEW-18704-1

National Aeronautics andSpace Administration

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Technical Support Package

for

Hybrid Power Management-Based Vehicle Architecture

LEW-18704-1

NASA Tech Briefs

The information in this Technical Support Package comprises the documentation referenced in LEW-18704-1 of NASA Tech Briefs. It is provided under the Commercial Technology Program of the NationalAeronautics and Space Administration to make available the results of aerospace-related developmentsconsidered having wider technological, scientific, or commercial applications. Further assistance isavailable from sources listed in NASA Tech Briefson the page entitled NASA Innovative PartnershipsProgram.

For additional information regarding research and technology in this general area, contact:

Glenn Technology Transfer OfficeMail Stop 4-221000 Brookpark RoadCleveland, OH 44135

Telephone: (216) 433-3484E-mail:TTP@grc.nasa.gov

NOTICE: This document was prepared under the sponsorship of the National Aeronautics and SpaceAdministration. Neither the United States Government nor any person acting on behalf of the United StatesGovernment assumes any liability resulting from the use of the information contained in this document or warrantsthat such use will be free from privately owned rights. If trade names or manufacturers names are used in thisreport, it is for identification only. This usage does not constitute an official endorsement, either expressed orimplied, by the National Aeronautics and Space Administration.

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Hybrid Power Management-Based Vehicle Architecture

Brief Abstract

Society desires vehicles with reduced fuel consumption and reduced emissions. The NASA John H.

Glenn Research Center (GRC) has developed a Hybrid Power Management (HPM) based vehicle

architecture for space and terrestrial vehicles. HPM is the innovative integration of diverse, state-of-the-

art power devices in an optimal configuration for space and terrestrial applications. The appropriate

application and control of the various power devices significantly improves overall system performance

and efficiency. The basic vehicle architecture consists of a primary power source, and possibly other

power sources, providing all power to a common energy storage system, which is used to power the drive

motors and vehicle accessory systems, as well as provide power as an emergency power system. Each

component is independent, permitting it to be optimized for its intended purpose. The key element of

HPM is the energy storage system. All generated power is sent to the energy storage system, and all

loads derive their power from the energy storage system. This can significantly reduce the power

requirement of the primary power source, while increasing the vehicle reliability. Ultracapacitors are

ideal for HPM based energy storage systems due to their exceptionally long cycle life, high reliability,

high efficiency, high power density, and excellent low temperature performance. Multiple power sources

and multiple loads are easily incorporated into an HPM based vehicle. A gas turbine is a good primary

power source because of its high efficiency, high power density, long life, high reliability, and ability to

operate on a wide range of fuels. An HPM controller maintains optimal control over each vehicle

component. This flexible operating system can be applied to all vehicles to considerably improve vehicle

efficiency, reliability, safety, security, and performance.

Section I Description of the ProblemGeneral description of the problem: A hybrid electric vehicle typically utilizes batteries for energy

storage. The battery is the most vulnerable part of the hybrid vehicle, requiring regular maintenance and

replacement. Battery performance is also extremely temperature dependent. Ultracapacitors are ideal for

hybrid electric vehicles where long life, maintenance free operation, and excellent low temperature

performance are essential. The basic HPM vehicle architecture consists of a primary power source, and

possibly other power sources, providing all power to a common energy storage system, which is used to

power the drive motors and vehicle accessory systems, as well as provide power as an emergency power

system. Each component is independent, permitting it to be optimized for its intended purpose. The key

element of HPM is the energy storage system. All generated power is sent to the energy storage system,

and all loads derive their power from the energy storage system. This technique can significantly reduce

the power requirement of the primary power source, while increasing the vehicle reliability.

Ultracapacitors are ideal for HPM based energy storage systems due to their exceptionally long cycle life,

high reliability, high efficiency, high power density, and excellent low temperature performance.

Multiple power sources and multiple loads are easily incorporated into an HPM based vehicle. A gas

turbine makes an excellent primary power source due to its high efficiency, high power density, long life,

high reliability, and ability to operate on a wide range of fuels. A photovoltaic array makes an excellent

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secondary power source due to its long life, high reliability, and passive nature. A hybrid power

management controller maintains optimal control over each vehicle component. Concerns over utility

power system security have provided an incentive for a hybrid electric vehicle to act as an auxiliary utility

power system that can provide utility power in times of emergency, and also to supplement the utility

power system. The HPM vehicle architecture provides auxiliary power for this purpose. The HPM

vehicle architecture can be applied to all vehicles to considerably improve vehicle efficiency, reliability,

safety, security, and performance.

Key or unique problem characteristics: Existing hybrid electric vehicle energy storage systems have

power limitations and life limitations. These limitations cause performance, reliability, and cost barriers

for hybrid electric vehicles.

Prior techniques for energy storage:

1. Batteries.

2. Flywheels.

3. Pneumatics.4. Hydraulics.

5. Thermal.

Limitations of prior techniques:

1. Unable to handle high current levels. Limited life due to chemical reactions.

2. High production costs. Limited life of mechanical system.

3. High maintenance system. Low reliability.

4. High maintenance system. Low reliability.

5. High maintenance system. Low reliability.

Section II Technical DescriptionPurpose and description: The purpose of the HPM based vehicle architecture is to provide an efficient,

reliable, long life, vehicle system. HPM based vehicle systems are significant in all aspects of human life

by providing higher efficiency vehicles, increasing safety, and providing essential backup power, while

improving the environment, and stimulating the economy.

Identification of component parts:The basic HPM vehicle architecture consists of a primary power

source, and possibly other power sources, providing all power to a common energy storage system, which

is used to power the drive motors and vehicle accessory systems, as well as provide power as anemergency power system. Each component is independent, permitting it to be optimized for its intended

purpose. The key element of HPM is the energy storage system. All generated power is sent to the

energy storage system, and all loads derive their power from the energy storage system. Ultracapacitors

are ideal for HPM based energy storage systems due to their exceptionally long cycle life, high reliability,

high efficiency, high power density, and excellent low temperature performance. Multiple power sources

and multiple loads are easily incorporated into an HPM based vehicle. A gas turbine is a good primary

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power source due to its high efficiency, high power density, high reliability, and ability to operate on a

wide range of fuels. An HPM controller maintains optimal control over each component.

Functional operation:All generated power is sent to the energy storage system and all loads derive their

power from the energy storage system.

Alternate embodiments of this innovation:An alternative embodiment of the innovation is dedicated

energy absorbing systems optimized for that application.

Supportive theory:The theory is that an ultracapacitor is an electrochemical energy storage device, which

has an extremely high volumetric capacitance energy due to high surface area electrodes, and very small

electrode separation.

Engineering specifications:Carbon, KOH, carbon, ultracapacitor construction.

Peripheral equipment: Peripheral equipment includes the electric traction motors, electric accessories,and the hybrid power management controller.

Maintenance, reliability, and safety factors:The HPM based vehicle architecture has many advantages

over conventional vehicle architectures. Ultracapacitors have a much longer cycle life than batteries,

which greatly improves system reliability, reduces life-of-system costs, and reduces environmental

impact, as ultracapacitors will probably never need to be replaced and disposed of. The environmentally

safe ultracapacitor components reduce disposal concerns and their recyclable nature reduces the

environmental impact, as well as the life-of-system costs. High ultracapacitor power density provides

high power during surges, and the ability to absorb high power during recharging. Ultracapacitors are

extremely efficient in capturing recharging energy, rugged, reliable, maintenance free, have excellent lowtemperature characteristics, provide consistent performance over time, and promote safety, as they can be

left indefinitely in a safe discharged state, whereas batteries cannot.

Section III Unique or Novel Features of the Innovation

Novel or unique features: The unique feature of the HPM based vehicle architecture is the use of a

primary power source, and possibly other power sources, providing all power to a common energy

storage system, which is used to power the drive motors and vehicle accessory systems, as well as provide

power as an emergency power system. Each component is independent, permitting it to be optimized for

its intended purpose. The key element of HPM is the energy storage system. All generated power is sentto the energy storage system, and all loads derive their power from the energy storage system.

Ultracapacitors are ideal for HPM based energy storage systems due to their exceptionally long cycle life,

high reliability, high efficiency, high power density, and excellent low temperature performance.

Multiple power sources and multiple loads are easily incorporated into an HPM based vehicle. A gas

turbine is a good primary power source due to its high efficiency, high power density, high reliability, and

ability to operate on a wide range of fuels. An HPM controller maintains optimal control over each

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component.

Advantages of innovation: The HPM based vehicle architecture has many advantages over conventional

vehicle architectures. Ultracapacitors have a much longer cycle life than batteries, which greatly

improves system reliability, reduces life-of-system costs, and reduces environmental impact, as

ultracapacitors will probably never need to be replaced and disposed of. The environmentally safe

ultracapacitor components reduce disposal concerns and their recyclable nature reduces the environmental

impact, as well as the life-of-system costs. High ultracapacitor power density provides high power during

surges, and the ability to absorb high power during recharging. Ultracapacitors are extremely efficient in

capturing recharging energy, rugged, reliable, maintenance free, have excellent low temperature

characteristics, provide consistent performance over time, and promote safety, as they can be left

indefinitely in a safe discharged state, whereas batteries cannot. A gas turbine is an excellent primary

power source due to its high efficiency, high power density, high reliability, and ability to operate on a

wide range of fuels. Concerns over utility power system security has provided an incentive for a hybrid

electric vehicle to act as an auxiliary utility power system that can provide utility power in times of

emergency, and also to supplement the utility power system. The HPM vehicle architecture providesauxiliary power for this purpose. The HPM vehicle architecture can be applied to all vehicles to

considerably improve vehicle efficiency, reliability, safety, security, and performance.

Development of new conceptual problems: Maximum ultracapacitor temperature is limited to 200 degrees

F at this time.

Analysis of capabilities: See attachment.

Analysis of capabilities: The HPM based vehicle architecture has significant measurable value beyond

cost reduction, which itself is quite significant. There is a measurable improvement in efficiency, and anenvironmental improvement. Ultracapacitors are an enabling technology. Ultracapacitors greatly

improve system efficiency. The charge/discharge efficiency of rechargeable batteries is approximately

50%. The charge-discharge efficiency of ultracapacitors exceeds 90%. Thus there is a significant energy

savings through the efficiency improvement. The environmental impact of ultracapacitors is

extraordinary. The 20-year life of ultracapacitors would greatly reduce the disposal problems posed by

lead acid, nickel cadmium, lithium, and nickel metal hydride batteries. Ultracapacitors are recyclable in

nature, which further reduces the system costs. The disposal of ultracapacitors is extremely simple, as

they are constructed from non-hazardous components. The cost savings are extended as the down time

imposed by battery failure is eliminated, as well as the labor costs associated with frequent battery

replacement. Ultracapacitors are an enabling technology for hybrid vehicles. Conventional energystorage systems have thwarted the performance of hybrid vehicles. The long life, high efficiency, and

excellent low temperature characteristics of ultracapacitors makes hybrid vehicles practical. The HPM

based vehicle architecture readily accommodates a gas turbine as the primary power source, which has

high efficiency, long life, high reliability, and has the ability to operate on a wide range of fuels. The

HPM based vehicle architecture readily accommodates a photovoltaic array as a secondary power source,

which has long life, high reliability, and provides power in a passive nature. The HPM based vehicle

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architecture has the ability to act as an auxiliary power source for the utility power system, providing

emergency utility power in the event of loss of utility power, and can supplement the utility power system

to reduce the utility power system burden, providing additional safety and security.

Section IV Potential Commercial ApplicationsHPM based vehicles have tremendous potential. Combined global sales of hybrid electric vehicles and

battery electric vehicles are expected to reach 5.2 million vehicles in 2020. Many commercial and

government fleet managers are increasingly relying on hybrid electric vehicles to help protect their

budgets from increasing fuel costs and reduce emissions of their fleets. The fleet market for hybrid

electric vehicles is expected to grow at a rate of 18% between 2010 and 2015, resulting in sales of more

than 740,000 hybrid fleet vehicles worldwide in 2015. The primary concern of hybrid and battery electric

vehicle ownership is the cost of replacing the battery packs. The HPM based vehicle architecture

eliminates this concern, and can stimulate this industry.

There are several manufacturers of hybrid electric vehicles worldwide representing a tremendous

opportunity for the HPM vehicle architecture. The environmental impact of HPM based vehicles is

tremendous because of the large battery disposal issue posed by conventional hybrid electric vehicles,

which represents a significant additional cost.

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ATTACHMENTS FOR A HYBRID POWER MANAGEMENT (HPM)

BASED VEHICLE ARCHITECTURE

NASA FORM 1679

SECTION I

A.) PURPOSE AND DESCRIPTION

Society desires vehicles with reduced fuel consumption and reduced emissions. This presents

a challenge and an opportunity for industry and the government. The NASA John H. GlennResearch Center (GRC) has developed a Hybrid Power Management (HPM) based vehicle

architecture for space and terrestrial vehicles. GRCs Electrical and Electromagnetics Branch of

the Avionics and Electrical Systems Division initiated the HPM Program for the GRC

Technology Transfer and Partnership Office. HPM is the innovative integration of diverse, state-

of-the-art power devices in an optimal configuration for space and terrestrial applications. The

appropriate application and control of the various power devices significantly improves overall

system performance and efficiency.

The basic vehicle architecture consists of a primary power source, and possibly other powersources, providing all power to a common energy storage system, which is used to power the

drive motors and vehicle accessory systems, as well as provide power as an emergency power

system. Each component is independent, permitting it to be optimized for its intended purpose.

This flexible vehicle architecture can be applied to all vehicles to considerably improve system

efficiency, reliability, safety, security, and performance. This unique vehicle architecture has the

potential to alleviate global energy concerns, improve the environment, stimulate the economy,

and enable new missions. The concept is shown in Figure 1.

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Figure 1 General HPM Vehicle Architecture

The general HPM vehicle architecture discussed here consists of electric motors for tractiondrive and regenerative braking, powered by multiple primary power sources, with an energy

storage system, and all electric accessories, controlled by an HPM power management

controller.

The evolution of power electronics technology has offered the possibility of revolutionary drive

trains for vehicles. Electric motors using efficient solid-state power devices offer infinitely

variable power and speed control. Several of the motors currently being offered by industry

have very high power densities and can be controlled to also act as generators. When coupled

with onboard energy storage systems, such as batteries, flywheels, or ultracapacitors, this drivetrain offers several advantages including:

Improved fuel economy Reduced emissions

Lower noise levels

Elimination of multiple-gear transmissions Elimination of fluid coupling losses

Near constant speed and load to the primary power source

Recovery of energy during braking

Reduced drive train and brake maintenance Flexible vehicle configuration for improved vehicle design

Electrical power trains with energy storage uncouple the short-term power requirements of the

vehicle from the load seen by the primary power source. Thus the primary power source in

such a power train can operate at its highest efficiency design point. In addition, the size of the

primary power source can be reduced significantly in some vehicles and drive cycles to the

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long-term average value of power. Energy storage provides the short-term power supplement

needed during acceleration and for going up a grade. This reduced power source size, higher

efficiency, and constant speed yields significantly improved emissions, fuel economy, and life

for the primary power source.

The energy storage system is necessary to provide a smooth power requirement to the primary

power source and as a place to absorb the regenerative braking energy. Regenerative braking

significantly improves vehicle efficiency, and braking performance, providing consistent braking

over time. Regenerative braking can be used to perform complete stops under most driving

conditions, which significantly extends mechanical brake life, thus improving safety and

reliability, and reducing maintenance costs.

The individually powered electric accessories (such as air conditioning, power steering, and

power brakes) eliminate the parasitic loads of the accessories as they are only operated whenrequired. This improves economy and life. This configuration also allows the accessories to be

located in the optimum location in the vehicle, rather than a central location.

The HPM vehicle architecture also provides an auxiliary power system for facility power. This is

used as an emergency backup power system in the event of a utility power system failure. It

can also be used to supplement the utility power system.

The energy storage system allows the vehicle to readily accommodate multiple power sources.

Multiple power sources can improve vehicle efficiency, and allows accessories, such as the air

conditioning, to be operated when the primary power source is not operating. The additional

power sources can also be used for the auxiliary power system.

The HPM power management controller provides control over the entire vehicle power system

to maintain optimum efficiency and safety.

Traction Motors

Electric wheel motors are optimal for the HPM vehicle architecture. Electric motors produce

maximum torque at zero speed, which is ideally suited for vehicle operations. Electric motors

provide consistent performance over their life, unlike internal combustion engines whose

performance degrades. The motors provide infinitely variable speed control. This eliminates

the need for a transmission, which saves weight and cost, and improves efficiency and

reliability. Electric wheel motors provide optimal drive and braking characteristics. Any

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quantities of drive wheels are possible with this technology. This configuration facilitates

traction control, anti-skid braking, and yaw control through the dynamic control of the motors.

Multiple wheel motors permit the use of tires with decreased aerodynamic drag and rolling

resistance. Regenerative braking significantly improves vehicle efficiency, and braking

performance, providing consistent braking over time. Regenerative braking can be used to

perform complete stops under most driving conditions, which significantly extends mechanicalbrake life, thus improving safety and reliability, and reducing maintenance costs. Regenerative

braking reduces the emission of brake material and heat produced by mechanical brakes. It

also significantly reduces the environmental concern from brake disposal. Mechanical brakes

must be provided for braking at very low speeds, and as a backup for the regenerative braking

in the event of a motor control failure.

Ultracapacitor Energy Storage System

The central feature of HPM is the energy storage system. All generated power is sent to the

energy storage system, and all loads derive their power from the energy storage system. An

HPM energy storage system must be extremely reliable, have an extensive life, and must have

very high efficiency, since all generated power is sent to the energy storage system, and all

loads derive their power from the energy storage system. The ultracapacitor is an ideal

candidate for an HPM energy storage system. A capacitor is an electrical energy storage

device consisting of two or more conducting electrodes separated from one another by an

insulating dielectric. An ultracapacitor is an electrochemical energy storage device, which has

extremely high volumetric capacitance energy due to high surface area electrodes, and very

small electrode separation. Commercially available ultracapacitors provide a reliable, long life,

maintenance free, energy storage system, and have many advantages over energy storagesystems such as batteries.

Batteries can only be charged and discharged hundreds of times, and then must be replaced.Ultracapacitors can be charged and discharged over 1 million times. The long cycle life ofultracapacitors greatly improves system reliability, and reduces life-of-system costs.

Long ultracapacitor life significantly reduces environmental impact, as ultracapacitors willprobably never need to be replaced and disposed of in most applications.

The environmentally safe components of ultracapacitors greatly reduce disposal concerns.

High ultracapacitor power density provides high power during acceleration, and the ability to

absorb high power during regenerative braking. Ultracapacitors are extremely efficient incapturing regenerative braking energy.

Ultracapacitors are extremely rugged, reliable, and maintenance free.

Ultracapacitors have excellent low temperature characteristics. Ultracapacitors provide consistent performance over time.

Ultracapacitors promote safety, as they can easily be discharged, and left indefinitely in a

safe discharged state.

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Gas Turbine Generator

Electric utility power was originally provided by reciprocating engines. Turbine generators were

then implemented which provided greater efficiency, improved reliability, and longer life, and

became the standard power source. Gas turbine generators are commercially available and arean ideal power source for the HPM vehicle architecture. In spite of the many advantages of the

gas turbine over the internal combustion engine, it does not make a good power source to drive

the vehicle directly because it does not throttle very well, requiring optimum speed operation to

achieve good efficiency. Turbines also have throttle lag. These problems are resolved with a

hybrid configuration in which the turbine is configured as an electric generator to power the

electric drive motors. The turbine can be operated at the optimum speed in a hybrid

configuration. The gas turbine generator offers many advantages over reciprocating engines.

Higher efficiency.

Higher power density.

Reduced emissions.

Operational on alternative fuels.

Smooth and quiet operation.

High reliability.

Lower maintenance.

Longer life.

Parts count reduced by 80%.

Lower manufacturing costs.

Solitary start-up spark plug eliminating a distributor.

Regular oil changes not required as no combustion contaminants enter oil.

No water-cooling system and antifreeze required.

Easy low-temperature starting.

No warm-up required.

Instant heat available in the winter.

Multiple gas turbines can be used independently as HPM vehicle power sources. The

architecture permits one turbine to be used as a power source, and other turbines to be turned

on as necessary to meet the specific vehicle power requirement, and then shut down when not

required to limit fuel use and emissions. As other technologies, such as fuel cells, mature, they

may become credible alternatives for the HPM vehicle architecture power source in the future.

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Photovoltaic Power System

Modern photovoltaic (PV) panels are readily available, reliable, efficient, and economical with a

life expectancy of at least 25 years, and make an ideal secondary power source for the HPM

vehicle architecture. The PV panels are semiconductor panels that convert energy fromsunlight to DC electrical power. The panels are unbreakable and maintenance free. PV is

entirely pollution free during use. PV system production end wastes and emissions are

manageable utilizing existing pollution controls. End-of-use recycling technologies are under

development to minimize negative environmental effects. PV systems can operate with minimal

operator intervention or maintenance after initial setup.

Control System

The hybrid power management controller provides sequencing for system/subsystem startup

and shutdown as well as control of the state of discharge of the energy storage system. The

state of the energy storage must be optimized to allow for full recovery of energy during braking

while also providing adequate vehicle performance. The vehicle must respond to operator

accelerator and brake controls as similarly as possible to the response of a conventional

vehicle. The choice of the energy storage system and its associated electrical characteristics

strongly influences the design of the vehicle control strategy. The ultracapacitor system has

several characteristics that are significantly different from those of conventional chemical

storage batteries. First the state of charge of capacitors can be determined very precisely from

the measured capacitor voltage. This is a significant advantage over chemical batteries in which

the relationship between voltage and state of charge is non-linear. Chemical batteries also

exhibit hysteresis of their voltage, current, state of charge characteristics. Battery energy

storage systems require a much more sophisticated state of charge control system. A second

difference between batteries and capacitors is that batteries must be current (and/or cell

voltage), limited especially when being charged. This is even more critical as

the battery achieves full charge. Near full charge lead acid and many other chemical batteries

are unable to accept high currents without damage. To prevent loss of battery life, additional

hardware and software is needed which again adds complexity of the charge control system.

Ultracapacitors, on the other hand, have very high current capabilities and efficiency, approach

their voltage limit more slowly, and do not experience damage while accepting current below full

charge. Overall, the use of ultracapacitor energy storage reduces the complexity of the power

operation of the vehicle, which uses ultracapacitor voltage as feedback to control the power set

point, updated continuously, of the engine generator set.

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Auxiliary Power System

Society is concerned with the security of the electric utility system. The HPM architecture allows

the vehicle to serve as a mobile power generator. A gas turbine is an excellent long life power

source, and lends itself to use for this application. The generator can be used to power a home,and multiple vehicles can be used to power hospitals and other critical institutions. This

enhances safety and security. The photovoltaic power system is an ideal source for the

auxiliary power system during daylight hours. The photovoltaic power system can be used to

provide emergency backup power, and can also be used to supplement the utility power

system, reducing the burden on the utility. Parked school buses at a school could provide

much, and perhaps all, of the power required by the school during the day when the highest

level of power is required, significantly lowering fuel use, emissions, and energy costs.

Modern electronics is the enabling technology behind grid-tied power systems, making them

safe, reliable, efficient, and economical with a life expectancy of at least 25 years. A grid-tied

power system is connected directly to the utility distribution grid. Facility power can be obtainedfrom the utility system as normal. The auxiliary power system is synchronized with the utility

system. The auxiliary power system provides power for the facility, and excess power is

provided to the utility. For safety, an automatic transfer switch permits the vehicle to provide

power to the facility when utility power is unavailable, and automatically switch back to utility

power when it does become available.

Grid-tied power systems provide many benefits. Operating costs of a PV power system are low

compared to conventional power technologies. PV can displace the highest cost electricity

during times of peak demand in most climatic regions, and thus reduce grid loading. Net

metering is often used, in which independent power producers, such as PV power systems, are

connected to the utility grid via the customers main service panel and meter. When the PV

power system is generating more power than required at that location, the excess power is

provided to the utility grid. The customer pays the net of the power purchased when the on-site

power demand is greater than the on-site power production and the excess power that is

returned to the utility grid.

B.) FUNCTIONAL OPERATION

The basic HPM vehicle architecture consists of a primary power source, and possibly other

power sources, providing all power to a common energy storage system, which is used to power

the drive motors and vehicle accessory systems, as well as provide power as an emergency

power system. Each component is independent, permitting it to be optimized for its intended

purpose. The key element of HPM is the energy storage system. All generated power is sent to

the energy storage system, and all loads derive their power from the energy storage system.

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Ultracapacitors are ideal for HPM based energy storage systems due to their exceptionally long

cycle life, high reliability, high efficiency, high power density, and excellent low temperature

performance. Multiple power sources and multiple loads are easily incorporated into an HPM

based vehicle. A gas turbine is a good primary power source due to its high efficiency, high

power density, high reliability, and ability to operate on a wide range of fuels. An HPM controller

maintains optimal control over each component.

C.) ALTERNATIVE EMODIMENTS

The HPM based vehicle architecture described includes a single primary power source and a

single secondary power source. An alternative embodiment of this technology is to have

multiple, independent, primary and secondary power sources. This could be advantageous in

some applications in which it is desired to provide additional power from a variety of sources

into the single vehicle energy storage system.

D.) PERIPHERAL EQUIPMENT

The HPM based vehicle architecture requires a dedicated HPM controller to exploit the full

advantage of the primary power source, secondary power source, and ultracapacitor energy

storage system in this application. Rechargeable batteries must be charged very carefully to a

specific profile based upon battery voltage, current, temperature and age so as not to damage

the battery and perhaps cause a safety hazard. A tremendous advantage of ultracapacitors is

the non-critical nature of charging the ultracapacitors. Charging is based primarily upon voltage,

and the current is limited only by the electrical connections that are made to the ultracapacitors.

The non-critical nature of the ultracapacitor charging power results in a controller that is much

less complex, and much less costly, than a battery controller. The ultracapacitors can also be

charged must faster than is possible with batteries.

E.) MAINTENANCE, RELIABILITY, AND SAFETY FACTORS

The HPM based vehicle architecture has numerous benefits associated with maintainability,

reliability, and safety.

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In conventional hybrid electric vehicles, rechargeable batteries are used and battery failures are

common. A typical battery pack can only be charged 300 times, and then must be replaced.

Ultracapacitors can be charged over 1 million times. Batteries have performance degradation

over time that does not occur with ultracapacitors. Consistent performance over time is a

distinct advantage of the HPM based vehicle. The long ultracapacitor life significantly reduces

life-of-system costs, as the ultracapacitors will probably never have to be replaced in mostapplications. The reliability of the HPM based vehicle is significantly greater than a battery

based hybrid electric vehicle, due to the high reliability of the ultracapacitors. The low

temperature performance of ultracapacitors is significantly better than that of batteries, thus

providing excellent low temperature performance of the utility vehicle. Ultracapacitors can be

left indefinitely in a safe discharged state, and then charged quickly when needed, unlike

batteries that must be kept charged regularly, or will be permanently damaged. Ultracapacitors

are inherently safer than batteries in that there are no chemical reactions occurring within

ultracapacitors as there are in batteries.

The HPM based vehicle architecture has significant measurable value beyond cost reduction,

which itself is quite significant. There is a measurable improvement in efficiency, and an

environmental improvement. Ultracapacitors are an enabling technology. Ultracapacitors

greatly improves system efficiency. The charge-discharge efficiency of rechargeable batteries

is approximately 50%. The charge-discharge efficiency of ultracapacitors exceeds 90%. Thus

there is a significant energy savings through the efficiency improvement. The environmental

impact of ultracapacitors is extraordinary. The 20-year life of ultracapacitors would greatly

reduce the disposal problems posed by lead acid, nickel cadmium, lithium, and nickel metal

hydride batteries. Ultracapacitors are recyclable in nature, which further reduces the system

costs. The disposal of ultracapacitors is extremely simple, as they are constructed from non-

hazardous components. The cost savings are extended as the down time imposed by battery

failure is eliminated, as well as the labor costs associated with frequent battery replacement.

Ultracapacitors are an enabling technology for hybrid vehicles. Conventional energy storage

systems have thwarted the performance of hybrid vehicles. The long life, high efficiency, and

excellent low temperature characteristics of ultracapacitors makes hybrid vehicles practical.

The HPM based vehicle architecture readily accommodates a gas turbine as the primary power

source, which has high efficiency, long life, high reliability, and has the ability to operate on a

wide range of fuels. The HPM based vehicle architecture readily accommodates a photovoltaic

array as a secondary power source, which has long life, high reliability, and provides power in a

passive nature. The HPM based vehicle architecture has the ability to act as an auxiliary power

source for the utility power system, providing emergency utility power in the event of loss ofutility power, and can supplement the utility power system to reduce the utility power system

burden, providing additional safety and security.

SECTION II

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A.) DEVELOPMENT OF NEW CONCEPTUAL PROBLEMS

The overall development approach has been multidimensional including the energy storagesystem and the control system. The overall development approach for the energy storage

system is to thoroughly investigate the performance characteristics of the ultracapacitor system.

This allows for an in-depth understanding of the energy storage system. To accomplish this, a

significant amount of prototype hardware and testing equipment has been developed to

experimentally evaluate the design concept. The functional performance of HPM systems has

been evaluated. No new conceptual problems have been encountered to date. System

designs must be optimized to take full advantage of the performance capabilities of the HPM

vehicle architecture.

B.) TEST RESULTS

The prototype HPM systems were designed to demonstrate the practicality of using

ultracapacitor based energy storage systems in a vehicle application. Extensive laboratory and

field tests have verified the practicality of the HPM vehicle architecture.

C.) ANALYSIS OF CAPABILITIES

The prototype HPM systems have clearly demonstrated the capability and many advantages of

this technology. Investigations have demonstrated excellent correlation between predicted

operation of the HPM vehicle architecture and experimental results. It is anticipated that the

invention will provide an excellent design solution for future vehicles.