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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


Version 1.0 Page 15

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.


Version 1.0 Page 18

*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.


Version 1.0 Page 19

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.


Version 1.0 Page 20

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

http://www.innovations-report.com/html/reports/automotive/mass_production_micro_hybrid_technology_set_cut_125526.html



http://www.hybridcars.com/types-systems/where-are-micro-hybrids-26042.html

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