ATT Conference
Barcelona, October 1-3, 2001
How to improve hybrid vehicles for
environmental sustainability.
A case study of their impact.
Antonio MATTUCCI, Mario CONTE, Giovanni PEDE
ENEA – Advanced Energy Technologies Division
C.R. Casaccia - Via Anguillarese 301
00060 Rome (Italy)
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ENEA SPECIFIC ACTIVITIES IN
TRANSPORT FIELD
Among the ENEA interests in the transport field, special
attention is paid to the vehicle efficiency and environmental
impact; in particular with:

Realisation of integrated facilities to assist design and
testing of electric and hybrid vehicles and specific
components of the traction system

Fleet tests under operational conditions of hybrid vehicles

Fuel cells and H2 Program
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Vehicle drivetrain integrated testing
facility
The main parts of the facility,
interconnected each other in
order to provide high test
flexibility , are:

Power generation section


Energy storage section
Driving motors section

Integrated control room
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Fleet test of hybrid vehicles
Public transport fleets have been tested in three selected
cities, where 24 IVECO 490 buses have been purchased and
operated for 3 year (1997-1999)



4 in Terni
8 in Ferrara
12 in Rome
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Fleet test of hybrid vehicles
IVECO 490 hybrid bus characteristics

2.8 l diesel engine

30 kW DC electric generator
164 kW AC electric motor
60 kWh capacity lead acid
batteries
200-300 km range of in thermal
mode and 20 km in pure electric
mode
60 km/h max speed
manual selection of driving mode





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Fleet test of hybrid vehicles
Hybrid and conventional bus test results
Vehicle
EURO II
Bus
Series
Hybrid Bus
Fuel
Consumption
(L/km)
CO specific
emissions
(g/km)
VOC specific NOx specific
emissions
emissions
(g/km)
(g/km)
0.437
5.05
0.82
24.92
0.41
0.3
0.59
11.55
Need of a control system to increase
hybrid vehicle efficiency
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Hybrid vehicle control system framework

Series hybrid vehicle fuel consumption dependent on battery
State Of Charge (SOC) and generator power

Test campaign to get additional information on hybrid
specific consumption, using a purpose-designed series hybrid
vehicle with the same driveline of 6m ALTROBUS

Control strategy constrains the battery SOC to stay in a
selected interval and allows modifications of the thermal
engine working point, with variations in a range of 20-25%,
as in such interval the environmental and energetic efficiency
remains high
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Hybrid vehicle driveline characteristics
Internal combustion engine
 1.2 l diesel engine
 24 kW max power (@ 3600 rpm)
 2200 rpm rating speed
Synchronous PM Machine
 10 kW rating power (@ 2200
rpm)
Storage system (battery)
 96 lead acid cells
 100 Ah capacity, 192 V
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IVECO Daily hybrid vehicle layout
Electric Propulsion System
Brake
Fuel
Accelerator
P=K
ICE
Wheel
Controller
AC
Generator
Generation System
Battery
Charger
DC/DC
DC
Chopper
Motor
Gear
Battery
Pack
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Wheel
9
Hybrid vehicle DC source behaviour
Specific Consumption
rpm
Ps
= variable-speed, minimum-consumption curve
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Daily hybrid vehicle controller development







Low cost controller, 200 ms. sampling time
Step by step controller development
Final controller version based on a forecast of the power
required (based on previous average power + trip route)
Controller algorithm processes data related to battery
voltage, current and SOC
First controller version has no power forecast and requires
manual setting of: generator power and SOC interval limits
Controller switches on-off the thermal engine to keep the
battery SOC between predefined limits
Controller effectiveness verified by means of many tests
based on European, American and Japanese cycles
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Daily hybrid vehicle test results
Driving cycle /
Main parameters
Unit
Driven distance
Km
Average traction
power
W
Total
traction
energy
Battery
charge/depletion
SOC (depletion
is positive)
Diesel
fuel
consumption
European
Cycle
(ECE/NEDC)
28.89
Japanese
Cycle
(1015)
American
Cycle
(UDDS)
19.80
26.96
7251
7370
9140
Wh
11384
9212
10785
W
-1.50
-1.20
5.80
Ah
-1.05
-0.84
4.06
Wh
-201.60
-161.28
779.52
kg
3.99
3.08
3.16
Wh
46765
36060
37085
1618.74
1821.26
1375.59
15.7
17.5
12.5
Wh/km
Equivalent fuel L/100 km
consumption
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Effectiveness of hybrid vehicle controller
Testing on the vehicle has shown the following results:
 Considerable improvement on fuel efficiency achieved,
especially for the American cycle
 Important to minimise start/stops of the thermal engine
 Next step with thermal engine load prediction requires
more sophistication for the control algorithm
 Need to modify the thermal engine working point (power
and speed) to gain additional efficiency
 30-40% of fuel consumption reduction achievable, with
similar benefits in terms of pollutant emission reduction
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Requirements for hybrid vehicle fleet
deployment effectiveness analysis
Main requirements
 Identification of effective application domains, where
hybrid vehicles can play a special role
 Measurability of resulting effects at global scale
 Different effects (such as pollutant emissions, fuel
consumption and even the resulting traffic conditions) to
be considered at the same time
 Identification of economically and technically affordable
deployment experiences
 Identification of appropriate analysis tools in order to
simulate the resulting scenario
 Use of conservative assumptions where sound information
is lacking
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LDVs viability for hybrid vehicle fleet
deployment application
Initial considerations
Light Duty Vehicles (LDVs) cover approximately 5% of
the Italian fleet (2 millions of vehicles)
 LDVs cover the main share of freight transport in
urban areas
 LDVs are responsible of relevant shares of pollutant
emissions in urban areas
 Results of ENEA hybrid vehicle experimental test
campaign fit perfectly LDVs behaviour
 TREMOVE model and reliable database are already
available for a deployment study

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Share of LDVs pollutant emission in
Italian urban areas
Impact of LDV in urban areas (year 2000)
8.6%
10.4%
4.3%
CO
10.4%
FC
NOx
0.7%
13.8%
PM
C6H6
VOC
NMVOC
3.5%
CH4
28.8%
6.5%
SO2
N2O
CO2
6.4%
6.5%
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Hybrid LDVs reduction factors for
impact analysis
Reduction factors
Indicators
Gasoline LDV
Diesel LDV
CO emission
0.7
0.1
NOx emission
0.7
0.5
VOC emission
0.7
0.7
PM emission
1.0
0.6
Fuel consumption
0.9
0.9
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LDVs behaviour
Fuel specific consumption for Light Duty vehicles
180
160
Conventional
Gasoline LDV
140
Euro IV Gasoline
LDV
g/km
120
100
Hybrid Euro IV
Gasoline LDV
80
Conventional
Diesel LDV
60
40
Euro IV Diesel
LDV
20
Hybrid Euro IV
Diesel LDV
0
10
15
20
25
30
35
40
45
50
55
60
65
70
Vehicle average speed (km/h)
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LDVs behaviour
CO specific emissions for Light Duty vehicles
Conventional
Gasoline LDV
50
45
Euro IV Gasoline
LDV
40
g/km
35
Hybrid Euro IV
Gasoline LDV
30
25
Conventional
Diesel LDV
20
15
Euro IV Diesel
LDV
10
5
0
10
15
20
25
30
35
40
45
50
55
60
65
70
Hybrid Euro IV
Diesel LDV
Vehicle average speed (km/h)
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Hybrid LDVs urban deployment study
Milan city selected for the analysis
 142000 LDVs operating in Milan area
 Introduction of hybrid LDVs begins in year 2002
 The shares of new hybrid LDVs covers 20% in the year
2002, 55% in 2003 and 100% in 2004 and beyond
 Total extra-cost in 2002-2005 is about 174 MEuros, of
which 12 in the year 2002 (2000 new LDVs deployed)
 Two scenarios have been analysed with TREMOVE
model, the first one only with hybrid introduction and the
second one with also the integration of telematic systems
to improve freight delivery effectiveness

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Hybrid LDVs first scenario results
Years 2002
2003
2004
2005
2006
2007
2008
2009
2010
0.00%
-1.00%
Emission Reduction (%)
to
reference basecase
shows relevant
differences only on
emissions
 Considerable effect
specially on PM
( 5%)
 After 2008 no more
PM reduction as
almost all the
oldest and dirtiest
LDVs have been
removed
Impact of series hybrid LDV in Milan
 Comparison
-2.00%
-3.00%
-4.00%
CO
FC
NOx
PM
VOC
CO2
-5.00%
-6.00%
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Hybrid LDVs second scenario results
 Two
Impact of hybrid LDVs introduction in Milan: load increase scenario
2010
2009
2008
2007
2006
2005
2004
2003
2002
years
0%
-2%
-4%
Reduction (%)
beneficial
effects, i.e. direct
reduction of
emissions and
increase of
commercial speed,
respect to reference
basecase
 Relevant decrease of
all the pollutants
( >5%)
 Higher effects on
fuel consumption,
CO2 and CO
emission
-6%
CO
NOx
PM
-8%
C6H6
-10%
-12%
-14%
VOC
FC
-16%
CO2
-18%
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Conclusions
Fleet tests of hybrid vehicles have shown positive
performances and provided information for the fields
where additional research is required
 Series hybrid vehicles can be improved by the adoption of
a control system able to manage the battery SOC and the
thermal engine working point
 Series hybrid vehicles can provide good results for
applications in domains where both the vehicle efficiency
and emission reduction are to be considered
 The combination of hybrid technology with other
provisions (technological, legislative, informative, etc.)
can provide very important additional benefits

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