EE-VERT
© 2010 The EE-VERT consortium
Project acronym: EE-VERT
Project title: Energy Efficient VEhicles for Road Transport – EE-VERT
Grant Agreement Number: 218598
Programme: Seventh Framework programme, Theme 1.1, Greening
Contract type: Collaborative project
Start date of project: 1 January 2009
Duration: 36 months
Deliverable D2.1.3:
D2.1.3: Initial report into applicability to and impact on hybrid vehicles
Authors: Organisation Name
MIRA Bob Simpkin
CRF Carlo D’Ambrosio
BOSCH Marcus Abele
LEAR Antoni Ferré
UPT Ion Boldea
ECS Leo Rollenitz
Reviewers: Organisation Name
VTEC John Simonsson
ECS Klaus Nenninger
FH-J Raul Estrada Vazquez
Dissemination level: Public
Deliverable type: Report
Work Task Number: WT2.1
Version: 1.0
Due date: 31 October 2010
Actual submission date: 2 December 2010
Date of this Version 30 November 2010
EE-VERT
© 2010 The EE-VERT consortium
Consortium Members
Organisation Abbreviation Country
MIRA Limited MIRA GB
Volvo Technology AB VTEC SE
Centro Ricerche Fiat Società Consortile per Azioni CRF IT
Robert Bosch GmbH Bosch DE
LEAR Corporation Holding Spain SLU Lear ES
Engineering Center Steyr GmbH & Co KG /
MAGNA Powertrain
ECS AT
FH-JOANNEUM Gesellschaft mbH FH-J AT
Universitatea “Politehnica” din Timisoara UPT RO
SC Beespeed Automatizari SRL BEE RO
EE-VERT Deliverable D2.1.3 30 November 2010
Document history
Version Description Planned
date
Actual
date
0.1 First internal version of deliverable with all contributions 20/10/2010 02/11/2010
1.0 First version of deliverable 12/11/2010 30/11/2010
A brief summary
Despite improvements in modern vehicles, a considerable amount of energy is still wasted due to the
lack of an overall on-board energy management strategy. Further electrification of auxiliary systems
promises energy and efficiency gains but there is an additional need for a coordinated approach to the
generation, distribution and use of energy.
The project “EE-VERT” is concerned with improving the energy efficiency of conventional vehicles.
The central concept is the electrification of auxiliary systems, and supplying their energy by recovered
energy from new sources or wasted energy such as recuperation of braking energy, waste heat
recovery or solar cells.
Since hybrid vehicles also use combustion engines and many standard auxiliary systems the project
will also identify the use of EE-VERT smart components and concepts for hybrid applications.
Within WP2 the concepts and solutions for smart components are being developed, which are
necessary for the conversion, storage and distribution of energy with minimised losses. WP2 is also
concerned with the necessary power electronics for the components. The power electronics have to be
studied in EE-VERT since the energy management concepts require novel approaches to overcome
the system integration issues which include optimal electrical power conversion, thermal management
and electromagnetic interference. WP2 is also addressing the link between the EE-VERT approach
and hybrid vehicles. Hybrid vehicles have a high potential to reduce CO2 emissions but they require
cost-intensive and drastic technical modifications. EE-VERT has the objective to improve standard
vehicles by an overall energy management approach using smart components with a moderate
increase in costs. EE-VERT is evaluating several electrically driven auxiliary devices. Since hybrid
vehicles use also many standard components and electrified auxiliaries WP2 will also identify the use
of EE-VERT components for hybrid applications. This will include electrical components and loads
with high energy efficiency, technologies for reuse of thermal energy, predictive algorithms for
energy optimised operation and components or technologies for recuperation of braking energy.
This report firstly discusses the relative positioning of conventional vehicles, the EE-VERT concept
and hybrid vehicles, reviews the types of hybrid vehicles available, the typical components and
functions used. Secondly the EE-VERT approach including energy recovery and the use of optimised
electrified components and its application to hybrid vehicles is discussed. Finally an initial cost-
benefit analysis of the EE-VERT concept relative to conventional and hybrid powertrains is
discussed.
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Contents
A BRIEF SUMMARY ..................................................................................................................... 1
1 INTRODUCTION ................................................................................................................... 3
1.1 BACKGROUND .................................................................................................................... 3
1.2 PURPOSE ............................................................................................................................ 3
1.3 SCOPE ................................................................................................................................ 4
2 EE-VERT AND HYBRID VEHICLES ................................................................................... 5
3 TYPES OF HYBRID VEHICLES .......................................................................................... 6
3.1 MICRO HYBRIDS ................................................................................................................ 6
3.2 MILD HYBRID .................................................................................................................... 7
3.3 FULL HYBRID: SERIES DRIVETRAIN .................................................................................... 7
3.4 FULL HYBRID: PARALLEL DRIVETRAIN .............................................................................. 7
3.5 FULL HYBRID: SERIES/PARALLEL DRIVETRAIN .................................................................. 8
4 COMPONENTS AND THEIR CHARACTERISTICS .......................................................... 8
4.1 MIPEC ............................................................................................................................... 8
4.2 GENERATOR ..................................................................................................................... 10
4.3 LITHIUM ION BATTERY ..................................................................................................... 11
4.4 ELECTRIC AC COMPRESSOR ACTUATOR ............................................................................ 12
4.5 ENGINE COOLING FAN ...................................................................................................... 12
4.6 ELECTRICAL FUEL PUMP ................................................................................................... 14
4.7 VTG TURBO CHARGER, ELECTRIC ACTUATOR .................................................................. 14
4.8 VACUUM PUMP ................................................................................................................. 16
5 COST-BENEFIT ANALYSIS OF EE-VERT AND OTHER POWERTRAIN CONCEPTS
16
6 OPERATING MODES .......................................................................................................... 18
CONCLUSIONS AND OUTLOOK .............................................................................................. 20
REFERENCES .............................................................................................................................. 21
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1 Introduction
1.1 Background
The electrical system in conventional vehicles consists of a single electrical power bus, a generator
mechanically linked to the engine, an energy storage device (usually a 12V lead acid battery) and
many different loads. In present-day vehicles, even in those regarded as state-of-the-art electrical
power is generated with little knowledge of the actual loads. In general, the energy required for
auxiliary systems (e.g. power steering, water pump, oil pump) is generated and consumed
continuously, regardless of demand. Similarly, the energy generation for the vehicle’s electrical
system operates continuously.
Despite improvements in modern vehicles, a considerable amount of energy is still wasted due to the
lack of an overall on-board energy management strategy. Further electrification of auxiliary systems
promises energy and efficiency gains but there is an additional need for a coordinated approach to the
generation, distribution and use of energy.
The central EE-VERT concept is the electrification of auxiliary systems, and supplying their energy
by a high efficient electrical power generation. The EE-VERT concept considers the combination of
several different approaches to energy saving within an overall energy management strategy (thermal
and electrical). The approaches include:
Greater efficiency in energy generation with a new concept for the electrical generator and an
optimised overall operation strategy;
Energy recovery from wasted energy such as waste heat recovery or an optimised braking
energy recuperation with a temporarily increased generator output power with up to 6-10 kW
at a higher voltage level;
Energy scavenging from unused and new energy sources, for example the use of solar cells;
Greater efficiency in energy use by electrification of auxiliary systems with a very high
efficiency and an optimised overall operation strategy.
1.2 Purpose
This report firstly discusses the relative positioning of conventional vehicles, the EE-VERT concept
and hybrid vehicles, reviews the types of hybrid vehicles available, the typical components and
functions used. Secondly the EE-VERT approach including energy recovery and the use of optimised
electrified components and its application to hybrid vehicles is discussed. Finally an initial cost-
benefit analysis of the EE-VERT concept relative to conventional and hybrid powertrains is
discussed.
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1.3 Scope
Within WP2 concepts and solutions for smart components are being developed, which are necessary
for the conversion, storage and distribution of energy with minimised losses. WP2 is also concerned
with the necessary power electronics for the components. The power electronics have to be studied in
EE-VERT since the energy management concepts require novel approaches to overcome the system
integration issues which include optimal electrical power conversion, thermal management and
electromagnetic interference. WP2 is also addressing the link between the EE-VERT approach and
hybrid vehicles. Hybrid vehicles have a high potential to reduce CO2 emissions but they require cost-
intensive and drastic technical modifications. EE-VERT has the objective to improve standard
vehicles by an overall energy management approach using smart components with a moderate
increase in costs. Since hybrid vehicles also use many standard components WP2 will also identify
the use of EE-VERT smart components for hybrid applications. This will include electrical
components and loads with high energy efficiency, technologies for reuse of thermal energy,
predictive algorithms for energy optimised operation and components or technologies for recuperation
of braking energy.
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2 EE-VERT and Hybrid Vehicles
Hybrid Electric Vehicles (HEVs) have a good CO2 benefit but only a slow market penetration. Full
Electric Vehicles (EVs) are even further away from forming a significant proportion of the vehicle
market. Consequently conventional vehicles will play a significant role for the next decades. So there
is a gap in the market between present conventional vehicles and HEVs/EVs (Figure 2-1).
Figure 2-1 Market gap between present conventional vehicles and HEVs/EVs bridged by EE-
VERT
EE-VERT is seeking to develop marketable energy saving technologies with an attractive cost-benefit
ratio for conventional vehicles that have the potential for rapid launch and market penetration to
bridge this gap.
The central EE-VERT concept is the electrification of auxiliary systems and supplying their energy by
CO2-neutral recovered braking energy, waste heat recovery and solar cells. Some components will be
added while some other inefficient components will be replaced by new and smart components.
Consequently an initial study was set up during quarter 7 in WP2 to estimate the additional costs and
the potential benefit of the EE-VERT approach. This is the first step towards a full cost-benefit
analysis. A more accurate analysis will come later when simulation, test-bench and demonstrator car
results are available.
EE-VERT MeasuresDemo
carComments
Additional
costs
Useful for
hybrids
Power Generation pessimistic optimistic pessimistic optimistic Target
Braking energy recuperation
(generator, Li-Ion, DC/DC, brake
pedal sensor)
lBraking energy supplies the basic el. power net
load of 350W (0,07l diesel/100Wel./100km)4.2% 4.2% 4.2% 4.2% 550 € yes
Use of solar energy
(solar panels, DC/DC)l
An average el. power of 100W can be supplied
by solar power (0,07l diesel/100Wel./100km)0.0% 0.0% 1.2% 1.2% 200 € yes
Reuse of thermal energy
(exhaust gas generator, DC/DC) - tbd tbd tbd
Electrified Auxiliaries
Electrical engine oil pump -
Demand oriented operation possible;
Engine pre-lubrication for start-stop i.e.
reduction of drag torque on starting ICE1.0% 2.0% 0.5% 1.0% 40 € yes
Electrical water pump -Up to 2% higher engine efficiency through
optimised thermal engine management0.5% 1.0% 0.5% 1.0% 40 € yes
Engine cooling fan lHigher engine efficiency through optimised
thermal management (cooling water temp)0.0% 0.0% 1.0% 2.0% 30 € yes
Electrical fuel pump l Reduced power via on-off operation mode 1.0% 2.0% 1.0% 2.0% 30 € yes
Electric power steering -Additional environmental aspect: no more
hydraulic oil for the steering system in vehicles2.0% 4.0% 1.0% 2.0% 150 € yes
Vacuum pump +
VTG Turbo charger (el. actuator)l
No engine start is necessary if loss of vacuum
occurs during stop-phase or free-wheeling1.0% 2.0% 1.0% 2.0% 60 € yes
Lights -LEDs have an increased lifetime compared with
standard lights0.0% 0.0% 0.0% 0.5% 50 € yes
AC compressor (el. actuated) l
Air conditioning operation is possible for several
minutes during stop-phase as it will be electrically
actuated0.0% 0.0% 2.0% 4.0% 250 € yes
EE-VERT concept 9.7% 15.2% 12.4% 19.9% 1,400 €
Demo car (not all comp.) 8.2% 12.2% 11.4% 17.4% 1,120 €
Benefits - table of CO2 reductions and additional costsBenefit range on
NEDC
Benefit range on
mission profile
Figure 2-2 Additional components and system costs from a manufacturer point of view
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Figure 2-2 shows the CO2 benefits and the estimated additional costs for the EE-VERT components as
analysed in WP2. The CO2 benefits are based on the results reported in D2.1.1 and D2.2.1 and on
system simulation results from WP3. The additional costs are given for each component and are
estimates based on the assumption that every component is in mass production comparable to the
replaced old component. Figure 2-2 shows furthermore that the achievable benefit of the EE-VERT
technology on real-life cycle is between 12 and 19%. The total benefit on NEDC is estimated between
11 and 17%. The wide range of the benefits results from the still to be implemented overall system
operation management. The system operation management will be developed in WP3 and
implemented in WP4.
3 Types of Hybrid Vehicles
In this section the main types of hybrid vehicles available are discussed in terms of their features and
characteristics and electrified auxiliaries. The basic electric-drive system types can be considered
under four hybrids headings micro; mild; full series or full parallel.
Summary
Type of Hybrid Micro Micro Mild Full Full Full
Range
extended
EV
Parallel Series/Parallel
Examples Smart
Fortwo
MHD
BMW Toyota
Crown
Chevrolet
Volt
Honda
Insight
Toyota
Prius
Ford
Escape
Voltages used 12V 12V 36V/12V 365V/12V 144V/12V 200V/12V 330V
Features
Brake
Regeneration
X
Solar panels Some
models for
cabin
ventilation
DC/DC
converter
X X
Table 3-1 Types of Hybrid Drive and Associated Features and Characteristics
3.1 Micro Hybrids
A micro-hybrid is the simplest kind of ICE-electric technology. It usually consists of an energy
storage device, (often a valve-regulated lead-acid battery), and a strengthened starter-motor that can
also act as a generator. The main feature of a micro hybrid is the 'stop-start' function. According to
various research studies, vehicles are at a standstill for one-third of the time while in urban areas.
Stop-start systems could help make cities quieter, boost fuel efficiency and reduce exhaust pipe
emissions. Stop-start systems operate by cutting the engine when the vehicle comes to a complete
standstill. The engine is switched back on when the driver releases the brake pedal.
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A first generation of alternator-based 'stop-start' system has been in serial production with Citroen, on
the C4 since 2004 and on Smart cars since 2007. This system performs a stop-start function that is
transparent to the driver: the belt-driven starter-alternator system shuts down the engine during idle
phases and automatically restarts the engine when the driver wants to move off. As a result, there is
no fuel consumption, gas emission, vibration or noise at standstill. In the European standard driving
cycle, fuel consumption is reduced by 6%; while in congested urban traffic, savings of up to 25%
have been observed [6, 7]. However, disadvantages to this type of system can be the noticeable
starting and stopping of the engine and the inability to run major electrical loads such as air
conditioning without the engine restarting. The typical operating range of SOC for the battery is 3%
(80-83%) [8].
3.2 Mild Hybrid
The main difference between a mild hybrid and a full hybrid is that the electric motor in a mild hybrid
does not propel the vehicle on its own. The internal combustion engine in a mild hybrid provides the
majority of the tractive effort. The function of the motor in a mild hybrid is limited to drive assist, and
restart of the vehicle after an idling stop. Improvement in fuel efficiency for the Mild Hybrid is not as
significant as that of the Full Hybrid. However, the conventional type of engine/transmission systems
needs no significant change with the mild hybrid.
The real benefit of the mild hybrid system is that it saves fuel by shutting off the gasoline engine
when the vehicle is stopped, braking or cruising. Also, the electric motor helps the internal
combustion engine restart reliably and efficiently. Mild hybrids offer the potential to down-size the
internal combustion engine with the electric motor assisting when required. Depending on the system,
some mild hybrids can also capture mechanical energy during braking.
3.3 Full Hybrid: Series Drivetrain
This is the simplest hybrid configuration. In a series hybrid, the electric motor is the only means of
providing power to the driving wheels. The motor receives electrical power from either the battery
pack or from a generator run by an internal combustion engine. The vehicle controller determines how
much of the power comes from the battery or the engine/generator set. Both the engine/generator and
regenerative braking recharge the battery pack. The engine is typically smaller than in a comparative
conventional vehicle in a series drivetrain because it can be optimised to deliver the average driving
power demands. The engine operates in a narrow power range near optimum efficiency. However,
the battery pack needs to be capable of delivering the maximum power demand of the motor,
consequently it is relatively large. This large battery and motor, along with the generator, add to the
cost, making series hybrids more expensive than parallel hybrids.
3.4 Full Hybrid: Parallel Drivetrain
With a parallel hybrid electric vehicle, both the engine and the electric motor generate the power that
drives the wheels. A supervisory controller allows these components to work together with the
transmission. This is the technology used in the Insight, Civic, and Accord hybrids from Honda.
Parallel hybrids can use a relative small battery pack and therefore rely mainly on regenerative
braking to keep it recharged. However, when power demands are low, parallel hybrids also utilize the
drive motor as a generator for supplemental recharging, much like an alternator in conventional cars.
Since, the engine is connected directly to the wheels in this configuration, it eliminates the
inefficiency of converting mechanical power to electricity and back again, which makes these hybrids
quite efficient on the motorway. Yet the same direct connection between the engine and the wheels
that increases cruising efficiency compared to a series hybrid does reduce, but not eliminate, the city
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driving efficiency benefits (i.e. the engine operates inefficiently in stop-and-go driving because it is
forced to meet the associated widely varying power demands).
3.5 Full Hybrid: Series/Parallel Drivetrain
This drivetrain merges the advantages and complications of the parallel and series drivetrains. By
combining the two designs, the engine can both drive the wheels directly (as in the parallel drivetrain)
and be effectively disconnected from the wheels so that only the electric motor powers the wheels (as
in the series drivetrain). The Toyota Prius uses this concept. A similar technology is used in the new
Ford Escape Hybrid. As a result of this dual drivetrain, the engine operates at near optimum efficiency
more frequently. At lower speeds it operates more as a series vehicle, while at high speeds, where the
series drivetrain is less efficient, the engine takes over and energy loss is minimized. This system
incurs higher costs than a pure parallel hybrid since it needs a generator, a larger battery pack, and
more computing power to control the dual system. However, the series/parallel drivetrain has the
potential to perform better than either of the series or parallel systems alone.
4 Components and their characteristics
4.1 MIPEC
The EE-VERT concept requires the development of a flexible and configurable architecture for
optimising fuel-economy that includes energy recovery and energy harvesting. In this sense, one of
the promising areas for improvement is the use of multiple power sources for feeding electric loads.
However, the connection and integration of multi power sources is not straightforward.
This assertion is especially apparent when examining the different options on the market: from micro
hybrid solutions working at 12-42V to full electric working at 400-600V with intermediate solutions
working at 42-100V. Furthermore, the range of energy sources available may work at different
voltage ranges. The same applies to the energy storage elements available on the vehicle.
So basically, the powernet has to accommodate several different power sources and storage systems,
operating at different voltages that should be capable of meeting the instantaneous electrical demands
that the vehicle may encounter under any condition.
To handle this scenario, a new device is required that has the following features:
a) Capable of computing the best storage/sources configuration based on vehicle conditions
b) Set up the appropriate energy flow path and transformation strategy
c) Combines the multi-voltage devices in one single power net line in a pseudo real time frame.
This device is described as the MIPEC (Multi-Input Power Electronics Converter).
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Figure 4-1 MIPEC general architecture
The MIPEC architecture, Figure 4-1, is based on two principal stages, a Smart Sources
connection/selections Bays (SSB) and the DC/DC converter itself. The aim of SSB is to connect-
disconnect at the appropriate time and system conditions, based on an Energy Management strategy,
the different sources/storage devices into the power converter. The SSB technology depends on the
power/dynamics of the application (IGBT, MOSFET, SCR, etc.) and the directionality of the power /
energy source (an alternator is unidirectional while a battery is intrinsically bi-directional).
Regarding the DC/DC converter, several proposals have already been made with the objective of
effectively combining various power sources and energy storage elements [9]-[11]. Combination
strategies include sharing the output filter capacitor, sharing some switches and energy transfer
inductor and capacitor, and sharing a magnetic core. These input combination methods are shown in
Figure 4-2.
(a) (b) (c)
Figure 4-2 MIPEC topologies (a) sharing output filter capacitor (b) sharing inductor, switch
and/or capacitor, (c) sharing magnetic core. From [9]
Implementations (a) and (b) are typically used in renewable energy installations and hybrid / electric
vehicle applications since they are easily matched with requirements for energy flow and operation
modes. In renewable energy installations, these implementations take the form of a unidirectional
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buck-boost converter. In hybrid and electric vehicles, these topologies are generally used to drive the
traction load. In this case, a bi-directional buck-boost converter is usually implemented such that the
converter acts as step up converter (boost converter) for one mode of operation and as step down
converter (buck converter) for the other mode of operation. Each power source is connected to the
DC-link by means of this bi-directional converter. Step up mode of operation is used in order to
transfer energy from each power source to the DC-link, where as step down operation is used to
charge both UC tank and battery storage system and to recover the braking energy. Finally, solution
(c) is preferred for developments such as battery chargers, i.e., incorporating a connection to the grid
for recharging the battery.
Depending on vehicle requirements and the degree of hybridization, the DC/DC converter is built
using the most appropriate topology. Within the EE-VERT project a MIPEC is under development
that will demonstrate the ability to interface multiple power sources (generator, solar panels, thermal
generator) into a powernet of self-configuring electrical devices.
4.2 Generator
EE-VERT has identified and selected a generator concept for the EE-VERT approach. The new
generator concept is based on a claw pole machine with integrated permanent magnets for flux
influence. Main characteristics of this concept are an increased efficiency during standard operation
and a short time boost power capability of up to 8kW during a braking phase of the vehicle.
Figure 4-3 Exploded view of the generator prototype
Due to the promising characteristics from the simulation analysis the new generator concept has been
transferred into prototyping phase. During the first and second quarter 2010 it has been assembled.
Since quarter 3 of 2010 the generator is in vehicle integration phase. Figure 4-3 shows and exploded
view of the generator prototype. Figure 4-4 shows the assembled generator.
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Figure 4-4 The assembled generator prototype
The generator is especially designed to deliver a high power during recuperation with up to 8 kW by
delivering additionally a high level of efficiency of up to 80 % during standard operation. The
dimensions of the new generator are only slightly increased. So this is a very interesting technology
concept also for electric machines for mild and micro hybrid vehicles.
4.3 Lithium ion battery
A 40V Lithium ion battery pack has been designed for use in the EE-VERT demonstrator vehicle. The
unit comprises of the following sub sections:
Battery Pack.
Power switching.
Cell voltage equalisation and battery pack monitor.
Cell bank voltage monitor.
The Battery Pack is designed to provide a nominal 40V and to accept a maximum charge power of
8kW for 10 seconds.
The internal support electronics carries out the following functions:
Monitors the total pack voltage.
Monitors the pack temperature.
Monitors the battery charging/discharging current.
Equalises each cell voltage during charging.
Provide separate warning signals for cell over and cell under voltages.
In addition, the individual paralleled cell voltages can be monitored using the Cell Bank Voltage
Monitor using an external digital volt meter.
The measurement of charge/discharge current, total pack voltage and the kW hour usage are
communicated by CAN to a User Interface connector. The warning signals for over and under cell
voltages and pack temperature, are available as discrete signals in the User Interface connector. These
signals must be used by the Vehicle Controller (the central energy management ECU) to terminate
charging or discharging when the over and under limits have been reached to prevent cell damage.
Charging can be terminated by the Vehicle Controller sending a message to the generator to reduce
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the current and also to tell the DC/DC to stop supplying current from the thermoelectric generator and
the solar panels.
4.4 Electric AC compressor actuator
The biggest benefit of an electric compressor is that it is independent of the engine. The motor speed,
and consequently mass flow, can be optimised in the most efficient manner (either for energy savings
or comfort provision). This is of particular benefit when the vehicle is stationary. With an engine
driven compressor the vehicle would have been idling, with quite a low engine speed and low mass
flow. An electric compressor can run at the speed to satisfy the demand.
For a car that uses a stop/start strategy, the AC would be off completely when the engine is off
whereas with an electric driven compressor it can still run. Another added benefit is that the electric
compressor is more responsive in that it can spin up to high speed very quickly, not something that
would happen if it was driven directly from the engine.
For the EE-VERT vehicle demonstrator the base power required from the electric compressor actuator
is 1.6kW at 6,000rpm with a maximum of 2.5kW at 8,000rpm and 40V minimum. The base load
torque is rather constant from 2,000rpm to 8,000rpm, 2.55Nm. The maximum load torque is 3Nm up
to 8,000rpm. The ambient temperature is 38C°.
As volume efficiency and initial costs are equally important constraints in automotive electric
actuators the permanent magnet synchronous motor, with a surface permanent magnet rotor is the
most promising candidate. A further benefit is that the design can be adapted for both the AC compressor and the water pump.
This electric actuator will be relevant to hybrid and pure EV vehicles for both the AC compressor and
water cooling circuits.
4.5 Engine cooling fan
On a conventional vehicle, the cooling fan is coupled to some heat exchanger to cool the vehicle
fluids. Typically on a passenger car the cooling system is made of a heat exchanger for the engine
water and a heat exchanger for the Freon of the climate circuit. The heat exchangers are exposed to
conducted air ventilation during normal vehicle cruising. If the non forced ventilation is not enough, it
is possible to start forced ventilation through the use of the fan. Typically on conventional passenger
cars the fan is electrical.
On a hybrid vehicle the cooling request may be more complex. A thermal engine is still present and
the fan is still required to cool the engine water and the fluid in the climate circuit. The battery pack,
the inverter and the electric motor require to be cooled; typically they have to be cooled at a lower
temperature (35°- 50°C) than the thermal engine (90°C-100°C). Additional heat exchangers may be
required and the climate compressor may be used to provide the additional cooling power if the
thermal exchange with the external environment through the heat exchanger is not enough. All these
issues lead to a design of a complex additional thermal circuit for the electric driveline: many
different layouts are possible: just one fan may be used to cool a pack of more heat exchangers or
more fans may be used for each heat exchanger.
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In any case the fan is electric and there is no need to change the voltage supply: the electrical power
request of the fan on a hybrid vehicle is not increased compared to a conventional vehicle. So the
electric fan will be supplied at 12V.
For such reason the EE-VERT approach to the smart electric fan (as discussed in D2.2.1 par 3.4) can
be used on a hybrid vehicle with the same benefit in terms of electric power demand reduction.
The fan has an impact on the electric balance of the vehicle and consequently on the vehicle fuel
consumption. Most fans have two rotation speeds: low and high speed. The control algorithm of the
fan is usually based on a threshold activation control (engine water, fluid of the climate circuit, water
of the electric powertrain), resulting in an activation based on three levels: zero, low and high speed.
The fan speed is related to the heat that it is possible to subtract to the heat exchangers. So three air-
forced cooling levels are also available, for example: 1kW, 3kW, 10kW. If the heat exchangers
require, for example, 4kW of thermal cooling, the result of the actual control strategy is that, at the
end in stabilized conditions, 10kW from the fan will be requested, with the fan running at high speed.
Excessive cooling power is produced, causing waste energy.
From an energy point of view, a better control would be to maintain the engine water temperature at a
fixed value (for example 98°C), using only the cooling power required to reach such a desired
temperature. The fan must provide a continuous speed regulation and not just a discrete three level
control. The electrical energy required with a continuous fan control is lower than the energy required
with a discrete speed levels control to achieve the same or even better performance (see Figure 4-5).
Level 1
Level 2
Level 3
Real ventilation need
Potential saving
Power [kW]
Figure 4-5 Potential energy saving on actual discrete level fan activation
For a conventional vehicle the estimated CO2 benefit in real life is about 1-2%, including the
additional benefits due to an improved thermal engine management. It is expected to have the same
benefit on a hybrid vehicle just related to the part of the mission in which the thermal engine is
switched on. The overall benefit during the full hybrid vehicle mission is expected to be lower, due to
the presence of parts of the mission in which the engine is off. Anyway when the engine is switched
off and the traction is provided by the electric drivetrain, cooling is required from the electric
drivetrain. The charge/discharge of the battery pack and the electric motor generating/recovering
power are source of heat due to their efficiency in power conversion. Depending on the efficiency of
the electric drivetrain a certain amount of heat must be dissipated. In this case the use of a smart fan
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can lead to a reduction of the electrical power request also during the time in which the engine is
switched off.
4.6 Electrical fuel pump
The low pressure fuel pump on gasoline or diesel engines is used to sink the fuel from the tank, raise
the fuel pressure and send it to the injector system of the engine. Electric fuel pumps are generally
located in the fuel tank, in order to use the fuel in the tank to cool the pump and to ensure a steady
supply of fuel.
The fuel pump is managed differently according to the key and the engine status. At key-on, with the
engine off, the fuel pump is running for some seconds to ensure that there is sufficient fuel pressure to
the circuit for the engine to start. When the fuel pressure reaches the required level the fuel pump
stops. When engine starts during cranking, the fuel pump runs continuously to maintain the fuel
pressure in the circuit. Pressure is regulated through a passive pressure regulator with excess fuel
returned to the fuel tank. When the engine is running the fuel pump is always working at its maximum
motor speed, regardless of the actual fuel flow required for engine performance.
The new management strategy adopted in EE-VERT (see D.2.2.1 par.3.3) will regulate the fuel rate of
the pump in order to assure the engine performance objectives while at the same time minimizing the
fuel recirculation. A minimum amount of fuel recirculation is required in a common rail injection
system. The regulation of the fuel rate is achieved through a current controlled driver applied on the
fuel pump DC motor.
Results indicate that a saving of about 6A @ 14V (84W electrical) may be expected under most
vehicle conditions. A hybrid vehicle is equipped with an internal combustion engine (ICE) and the
smart electrical fuel pump can be fitted to produce an electric energy saving on the low voltage (12V)
powernet. The hybrid vehicle will have the same savings as the conventional vehicle when the ICE is
operating. When the engine is switched off it is important to apply a strategy to switch off also the
fuel pump (typically the fuel pump is managed in conventional vehicles through the key signal) as in
Stop&Start vehicles.
4.7 VTG Turbo charger, electric actuator
The advantages of moving from vacuum control to electrical control of the VTG actuator include:
potential for more precise boost control
better response – reducing turbo lag
no need of vacuum as servo power
The VTG actuator has to fulfill the following requirements:
actuation range: 25mm
position accuracy: ±1%
response time: 100ms for 90% of full range
ambient temperature range -25°C to 150°C
vibration 15g rms
fit into the desired space and shape
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CAN control
position feedback
failure status report via CAN
A novel actuator is being designed to meet both the VTG actuator requirements as well as being
universal actuator suitable for under-bonnet applications. The design of the device is based on a
brushless DC motor coupled to a two stage planetary gear with integrated control electronics. The
BLDC motor promises high reliability and high efficiency without the need for an external position
sensor.
The electrically powered VTG actuator is ideally suited for use on small turbocharged diesel engines
that could be fitted to hybrid vehicles.
Figure 4-6 3-D model of the actuator design
Figure 4-7 Actuator prototype assembling
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4.8 Vacuum pump
CRF and Bosch have investigated the benefit and integration of an electrified vacuum pump (EVP)
for the demo car. CRF analysed that the fuel reduction is between 0.15 and 0.2l per 100km and
therefore very attractive for the project. Hence, it was decided to integrate a prototype for an EVP into
the demo car which has today a mechanically driven vacuum pump.
The EVP prototype was built up by Bosch in the second and third quarter of 2010 (Figure 12). So the
EVP is ready for use within EE-VERT. In the third quarter some performance measurements was
undertaken by Bosch. Furthermore the demo car integration has been started in the third quarter.
Figure 4-8 The electrified vacuum pump for the EE-VERT demonstrator car
The EVP is a dry running vane pump. It supports the brake booster at insufficient manifold
depression. This is especially useful for stop-start, catalyst heating, and for hybrid vehicles during
electric driving and free wheeling mode. It has a compact design at high flow rate performance with
low pressure pulse. The EVP is demand driven with reduced fuel consumption. It can provide stop-
start- and free wheeling operation at full brake performance. The EVP vehicle integration is now
independent from the combustion engine design with flexible mounting position possibility.
5 Cost-benefit analysis of EE-VERT and other powertrain
concepts
In quarter 7 of the EE-VERT project a first cost estimation was undertaken to calculate the additional
system costs of the EE-VERT approach from a vehicle manufacturer point of view. Furthermore a
first cost-benefit analysis was undertaken to compare EE-VERT costs and benefits with other
powertrain concepts.
Assumptions and boundary conditions for the cost-benefit analysis
The basic fuel consumption for the AR159 jtdm on NEDC is 5.9l diesel per 100km. Consequently a
reduction in fuel consumption of 1% is equal to 1.57g CO2 /km (1l diesel leads to 26.6g CO2/km).
0.07l diesel per 100km is necessary to generate an electrical power of 100W. The basic electrical
power net load was assumed to be 350W on real-life and NEDC.
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The benefits of the electrified auxiliaries come, at the moment, only from demand oriented operation
and from supplying the electrical energy from CO2-neutral energy sources like braking energy
recuperation or solar power. Additional benefits, for example from an optimised engine cooling
circuit with an increased ICE efficiency, are not yet included. Consequently there is still a potential
for a further increasing of the EE-VERT benefit.
fullhighmedium - highlowDegree of el. auxiliaries
0.0 %
0.0 %
0 € (reference)
no
low
Lead-acid
2.5 kW
14 V
highhighmediumRecuperation power
>10,000 €3,500 – 8,000 €1,400 € (target)Additional system costs
NiMh or Li-IonNiMhLead-acid and Li-IonStorage system
14 / 260 - 380 V14 / 144 - 288 V14 / 40 VPower net voltage level
yesyesnoElectric driving
30 - 50 %20 - 30 %9 - 15 %Fuel economy NEDC
25 – 40 %10 - 25 %12 – 19 %Fuel economy real-life
20 - 80 kW15 - 70 kW3.1 / 8 kW (Dual power machine)Electric machine power
fullhighmedium - highlowDegree of el. auxiliaries
0.0 %
0.0 %
0 € (reference)
no
low
Lead-acid
2.5 kW
14 V
highhighmediumRecuperation power
>10,000 €3,500 – 8,000 €1,400 € (target)Additional system costs
NiMh or Li-IonNiMhLead-acid and Li-IonStorage system
14 / 260 - 380 V14 / 144 - 288 V14 / 40 VPower net voltage level
yesyesnoElectric driving
30 - 50 %20 - 30 %9 - 15 %Fuel economy NEDC
25 – 40 %10 - 25 %12 – 19 %Fuel economy real-life
20 - 80 kW15 - 70 kW3.1 / 8 kW (Dual power machine)Electric machine power
For passenger cars EE-VERT HEV / PHEV EV
Degree of electrification
Conventional
vehicle*
*With start-stop and regenerative braking (recuperation of braking energy with Pel=<500W)
HEV = Hybrid Electric Vehicle; PHEV= Plug-in Hybrid Electric Vehicle; EV = Electric Vehicle
Reference
Storage
Alternative energy sources
Load # 1
Volt . stab .
Load # X + 1
Load # X
Volt . stab .
Load # N S
Lead acid Battery
High Power Loads G
Low voltage power net
DC/DC
converter
High voltage power net
Architectures
Characteristics
Figure 5-1Cost-benefit comparison of electrified powertrain concepts and classification of
EE-VERT
Figure 5-1 shows the classification of the EE-VERT system in comparison to other current powertrain
concepts. Figure 5-2 presents the cost-benefit comparison with conventional vehicles, HEVs and EVs.
It is obvious that the EE-VERT approach has a very attractive cost-benefit ratio. HEVs and EVs have
high additional system costs. Figure 5-2 considers at the moment only additional system costs for the
vehicle manufacturer. It contains some information from the report “Plug-in Hybrid and Battery-
Electric Vehicles” from the European Commission Joint Research Centre, Institute for Prospective
Studies 2009.
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*Reference vehicle is the Alfa Romeo 159 1.9jdtm
2,000 4,000 6,000 8,000 10,000 12,000
Degree of electrification
EE-VERT
100
90
80
70
60
50
40
30
20
10
Additional system costs [€]
EV
HEV / PHEV
Conventional reference vehicle
Source: JRC Technical Notes: “Plug-in Hybrid and Battery-Electric Vehicles”; European
Commission, Joint Research Centre, Institute for Prospective Studies, 2009.
159
143
127
111
95
80
64
48
32
16
CO
2E
mis
sio
n[g/km] [%]
Just additional system costs
Not yet included is the total cost of ownership
Market range due to:
- Vehicle class
- Driving cycle
- etc.
Figure 5-2 Cost-benefit comparison of current powertrain concepts
A total cost of ownership analysis is not yet done but will be undertaken in the ongoing project. Next
steps are the considering of the LCA and the total cost of ownership including component and system
maintenance and penalty tax on the CO2 emissions.
6 Operating modes
There are a number of operating modes that will be developed within the EE-VERT project that can
be used by specific classes of hybrid vehicles. The modes include:
Brake regeneration
During braking engine braking will be increased by raising the output of the generator. This will be in
the region of 8kW for 10 seconds. This energy will be stored in the lithium ion battery and used to
power the electrical auxiliaries.
AC when stationary
Since the AC compressor is electrically operated and connected to the 40V powernet it will be
possible to run the AC system when the car is stationary with the engine at idle or even with the
engine off, provided that the SOC of the lithium ion battery is over 40%.
Energy harvesting - Solar panel
The roof-mounted solar panel will be particularly beneficial when the car is parked in direct sunlight.
The electrical energy generated will be routed through the MIPEC into the powernet. Depending on
the circumstances the energy can be used to maintain the SOC of the lead acid battery, ventilate the
cabin or charge the lithium ion battery.
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Reliability of Cranking Capability of the Lead-acid battery
The availability of the lithium ion battery to recharge a depleted lead acid battery offers the ability to
always ensure that the cranking of the engine is always possible even if there has been a significant
drain on the 12V battery, perhaps related to an extended parking period. This ability would be
managed through the MIPEC.
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CONCLUSIONS AND OUTLOOK
Hybrid vehicles have a high potential to reduce CO2 emissions but they require cost-intensive and
drastic technical modifications. EE-VERT has the objective to improve standard vehicles by an
overall energy management approach using smart components with a moderate increase in costs. EE-
VERT is developing a dual voltage architecture to accommodate multiple power sources and
electrically driven auxiliary devices, and use predictive algorithms for the energy optimised operation
of components and energy management. Table 2 shows the potential applicability of EE-VERT
elements to micro, mild and full hybrid vehicle types.
Since hybrid vehicles use also many standard components and electrified auxiliaries WP2 will also
identify the use of EE-VERT components for hybrid applications. This will include electrical
components and loads with high energy efficiency, technologies for reuse of thermal energy,
predictive algorithms for energy optimised operation and components or technologies for recuperation
of braking energy.
Type of Hybrid Micro Mild Full
Typical Voltages used 12V 30-50V/12V 150-450V/12V
EE-VERT Developments
Dual voltage architecture *
MIPEC *
50V generator
40V Lithium ion battery
Electrified auxiliaries:
A/C compressor actuator
Engine cooling fan
Fuel pump
Vacuum pump
VTG actuator
Operating modes
Brake energy recuperation
Solar energy harvesting
AC at idle or engine off
Ensure cranking ability of 12V SLI battery
*Multiple power source input concept
Table 2 Potential Applicability of EE-VERT Elements to Hybrid Vehicles
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References
[1] EE-VERT Deliverable 1.1.1, State of the art and standards.
[2] EE-VERT Deliverable 1.2.1, Mission profiles.
[3] EE-VERT Deliverable 1.3.1, Requirements report.
[4] EE-VERT Deliverable 2.1.1, Power Generation Report.
[5] EE-VERT Deliverable 2.1.2, Simulation Models for Power Generation.
[6] http://www.innovations-
report.com/html/reports/automotive/mass_production_micro_hybrid_technology_set_cut_125
526.html
[7] http://www.hybridcars.com/types-systems/where-are-micro-hybrids-26042.html
[8] S. Schaeck, et al., J. Power Sources (2008), doi:10.1016/j.jpowsour.2008.10.061
[9] S. H. Choung and A. Kwasinski (2008) “Multiple-Input DC-DC Converter Topologies
Comparison,” IECON 2008
[10] Y-M. Chen, Y-Ch. Liu, and S-H. Lin (2006) “Double-Input PWM DC/DC Converter for
High-/Low-Voltage Sources”, IEEE Transactions on Industrial Electronics, Volume 53, Issue
5, pages 1538-1545, October 2006
[11] K.P. Yalamanchili, and M. Ferdowsi (2005) “Review of multiple input DC-DC converters for
electric and hybrid vehicles“, IEEE Conference on Vehicle Power and Propulsion 2005