development of a lightweight plug-in hybrid electric vehicle demonstrator
TRANSCRIPT
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
1/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
Development of a Lightweight Plug-in Hybrid Electric Vehicle
Demonstrator
Girish Muraleedharakurup, John Poxon, Andrew McGordon, Paul Jennings
WMG, University of Warwick,
Coventry, CV4 7AL, UK
Steve Cousins, Kevin Lindsey
Axon Automotive Ltd,
Wellingborough, NN29 7RL, UK
Abstract - This paper presents results and learning from the real life development of a technology
demonstrator vehicle Axon60. Axon60 is a light-weight plug-in hybrid electric vehicle, part of the
Low Carbon Vehicle Innovation Platform sponsored by the UK Technology Strategy Board and led by
Axon Automotive Ltd in partnership with Powertrain Technologies Ltd, Scott Bader and WMG. The
Axon60 uses a lightweight recycled carbon fibre structure, multi-fuel capable combustion engine and
an electric motor to achieve fuel economy of over 100mpg over legislative drive cycles and less than
50g/km of CO2. The plug-in hybrid vehicle using a 2kWh battery pack is able to achieve 10 miles of
electric only operation due to its lightweight aerodynamic design and highly efficient powertrain. This
paper shares the experiences gained during the conceptual studies in light weight body structure
development, driveline selection and prototype vehicle development. Copyright 2010 EVS25
Keywords: Hybrid vehicles, Plug-in Hybrid Vehicles, PHEV, Demonstrator, Lightweight.
1. IntroductionThe challenge to reduce greenhouse gas
emissions is forcing vehicle manufacturers to
aggressively look at the energy usage when
vehicles are designed, manufactured, used and
recycled. Road based transport currently
accounts for approximately 21 per cent of the
UK CO2 emissions and is seen as a priority
sector by the UK government [1]. The UK
government has set a target of 40% reduction in
greenhouse gas emissions by the end of 2020.
Various routes have been suggested to reduce the
road based CO2 emissions such as alternative
fuels, improvements in internal combustion
engine, hybrid powertrains and lightweight
vehicles [2]. A plug-in hybrid vehicle with its
low local emissions is one of the most promising
alternatives to conventional vehicles [3].
As part of the Low Carbon Vehicle Innovation
Platform sponsored by the UK Technology
Strategy Board, Axon Automotive in partnership
with Powertrain Technologies Ltd, Scott Bader
Ltd and WMG is leading a project to launch a
new lightweight plug-in hybrid vehicle Axon60. The new car is capable of achieving
high levels of energy efficiency without
compromising driver safety and comfort. The
project aim is to launch a plug-in hybrid
demonstration vehicle by Q1 2011 to assess
technical possibilities, user experience and
market potential for light weight plug-in hybrid
vehicles in the UK. This paper presents results
and experiences from real life development of
drivetrain components and control strategy of
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
2/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
the prototype vehicle.
2. BackgroundIn a study undertaken by the authors of this
paper, it has been forecasted that by 2020 up to
7.5% of the new vehicle registrations will be
hybrid vehicles [4]. Figure 1 shows the likely
adoption of hybrid electric vehicles (HEV) in the
UK. As highlighted in the study, factors such as
initial cost, charging infrastructure etc need
addressing to increase the market share of hybrid
vehicles in the UK.
Figure 1: Forecast of HEV growth in the UK
Several initiatives to support the adoption of
Low Carbon Vehicles (LCV) in the UK have
been launched by the Department for Transport
(DfT). One such initiative is the Low Carbon
Vehicles Innovation Platform set up by the
Technology Strategy Board (TSB) to support
programmes to deliver innovative solutions for
the automotive industry.
To financially support early adopters of hybrid
vehicles, the DfT also announced a grant of
5000 to low emission vehicles meeting certain
performance criteria outlined in Table 1 [5].
The Axon60 is one of the LCV projects
supported by the TSB to advance the uptake of
plug-in hybrid vehicles in the UK. The Axon60
is a two-year project which started in November
2008 with an aim to gather experience in
developing and launching plug-in hybrid
vehicles (PHEVs) in the UK market.
Table 1 : DfT financial incentive requirements
Description Requirements
Vehicle Type M1 (i.e. cars only)
Must be
- Battery electric- Plug-in hybrid or- Hydrogen fuel cell car
Emissions 0g/km for EV
Max 75g/km PHEV
Vehicle
performance
Min range 70 miles (113
km) EV
Min range 10 miles (16
km) PHEV
Max speed of at least
60mph (96kph)
Warranty Vehicle:
- 3 years or 75,000miles (120,000 km)
Battery
- 3 years- 5 (if requested by
consumer)
The project aims to develop a PHEV
demonstrator with an All Electric Range (AER)
capability of at least 10 miles over realistic drive
cycles. The demonstrator vehicle will be used to
understand technical possibilities and limitations
of hybrid vehicle components in real world
conditions.
The project is being carried out by a consortium
of four partners responsible for different aspects
of the vehicle development:
-Axon Automotive Ltd :Project management, Vehicle design,
Vehicle construction
-Powertrain Technologies Ltd:Engine development, Continuously
Variable Transmission (CVT) development,
Powertrain packaging
-Scott Bader Ltd:Resin development
2000 2005 2010 2015 2020 2025 20300
0.5
1
1.5
2
2.5
3
3.5
4x 10
5 Forecast of HEV Sales in the UK
Sales
Forecast
Actual Sales
95% Confidence Interval
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
3/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
-WMG:Drive cycle analysis, Hybrid vehicle
component selection, Control strategy
development, Cost Benefit Analysis
3. Axon60 vehicle architectureThe Axon60 is being developed to meet the
European Union M1 class category (2007/46/EC)
and hence has to meet certain technical
requirements.
To determine the preferred hybrid vehicle
architecture the team first did a market study to
identify the current competition and created a
comparison matrix. Once the comparison matrixwas generated a detailed analysis of different
hybrid vehicle architectures was conducted to
estimate the cost vs. benefit of each architecture.
While undertaking this analysis following
criteria were considered:
- Low cost route to 50g/km of CO2- Electric only operation capability- Drivable in real world conditions- Stop-Start capability- Regenerative braking capability- Minimum battery life of 3 years- Possibility for Vehicle-to-Grid (V2G)
An initial comparison matrix was developed by
WMG to compare the existing competition.
Vehicles which belonged to the A segment as
defined by UK SMMT were considered for
comparison. Some basic performance criteria
such as power-to-weight ratios and specific
power were calculated for all the existing car
models. Figure 2 shows the Axon vehicle when
compared to existing vehicles in A segment.
Once the performance metrics were identified, 8
hybrid vehicle architectures were considered for
the Axon project. These were:
i) Microii) Mild
iii) Seriesiv) Full Parallelv) Through The Road (TTR)vi) Powersplit (PS)vii) Compound Coupled Powersplit
(CCPS)viii) Combined
Figure 2: Axon comparison matrix
The need to have an AER ruled out micro and
mild hybrid architectures. To keep the hybrid
architecture as close as possible to the base Axon
vehicle led to discarding the series, PS and
CCPS architectures. Finally a full parallel
architecture was chosen for the Axon60 vehiclebased on ease of packaging. In this configuration
both the electric motor and engine can drive the
road wheels independent of each other achieved
through the use of a Continuously Variable
Transmission (CVT). The Axon60 vehicle
architecture is shown in figure 3.
Diff
CVTGearbox ICE
GearboxElectric
MachineBattery
Figure 3: Axon60 PHEV architecture
Matiz 0.8
Matiz 1.0
C1
Sirion 1.0
Picanto 1.0
107
Fortwo cabrio
Fortwo coup
Splash 1.0
Aygo 1.0
iQ 1.0
Yaris 1.0
Axon60
40
45
50
55
60
65
70
Power/Weight(kW/ton)
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
4/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
Table 2 is an excerpt from the vehicle technical
specification.
Table 2 : Axon60 vehicle technical specification
Attribute Specification
Acceleration 0-30 mph in 5.5 secs
Max top speed 85 mph
Max kerb weight 650 kg
Passing
performance
30-50 mph in 7 secs
Gasoline range 320 miles
Electric range 10 miles
3.1. Body and structureExisting vehicle designs typically use steel for
body and chassis which make them heavy,
leading to poor fuel economy. One method to
increase fuel economy is by reducing the vehicle
weight and improving aerodynamic efficiency.
The Axon60 project aims to manufacture a
carbon fibre composite car structure at minimum
weight whilst providing greater stiffness in all
aspects than current steel bodied vehicles. The
structure incorporates features which provide
higher impact tolerance for both for minor and
major collisions. The use of composites allow
more flexibility in the vehicle design leading to
better aerodynamic shapes and lower drag
coefficients. Figure 4 shows the aerodynamic
design package for the Axon vehicle.
Figure 4: Axon60 PHEV aerodynamic package
The use of carbon/epoxy composites also
enables the Axon60 to meet weight targets
without compromising safety. The use of
composites helps to keep the total kerb weight of
the vehicle to around 650kg (including hybrid
components).
Figure 5: Axon60 vehicle carbon fibre structure
As shown in figure 5, the Axon60 vehicle uses a
composite structure with lightweight bonded
panels offering several manufacturing as well as
performance advantages such as automated
preform manufacturing, rapid vehicle body
assembling with minimal fixtures and improved
structural efficiency.
The structure is designed to offer high torsional
stiffness at minimum weight to provide crash
energy absorption in excess of a steel structure.
The resultant structure is expected to have aweight of 70 kg and an associated torsional
rigidity of around 15000 Nm/degree.
3.2. Electric motor sizing and selectionIn the initial stages of concept development, DC,
AC induction and permanent magnet
synchronous motors were considered. Before
selecting the motor configurations, several
fundamental factors were considered.
DC motors are much simpler to install, control
and also less expensive, particularly as the DC
motor controllers are much less complex than
AC controllers. Also, DC motors can be driven
above their rated limits for short amounts of time
particularly suitable for vehicle operations such
as overtaking. Yet, DC motors require more
maintenance and the motor design is more
complicated than a comparable AC motor. DC
motors are quite inefficient when used as a
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
5/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
generator it will not meet some of the
regenerative braking requirements of the Axon
vehicle. It was also difficult to find an
appropriate DC motor size which met the Axon
performance requirements. Although a PM
motor is desirable for PHEVs, due to its highcost, PM motors were not considered for the
Axon application. Hence, for the Axon60 project,
an AC induction motor was chosen due to its
greater efficiency when operated as either a
motor or generator, low cost and availability of
AC motor controllers (off the shelf).
Once the motor architecture was identified, the
motor performance specification had to be
determined. The Axon60 vehicle is primarily
intended to be used as a city car but with
motorway capability. Since the vehicle has to be
used for real world applications, the project team
chose the ARTEMIS urban drive cycle [6] to
determine the power requirements for the AC
motor.
Figure 6 : Axon60 power requirement on the NEDC
cycle
Figure 7: Axon60 power requirement on the
ARTEMIS Urban drive cycle
The power requirements under the New
European Drive Cycle (NEDC) & ARTEMIS
urban cycle are shown in figures 6 and 7. Based
on figures 6, 7 and acceleration requirements for
0-30mph, a 12kW AC induction motor was
selected.
3.3. Battery sizing and selectionFor selecting the appropriate battery for the
Axon60 vehicle the following selection
parameters were considered:
- Energy density- Power density- Capital cost-
Life cost- Cycle life limitations- Depth of discharge- Charge acceptance- Temperature range- Self discharge
The three major battery chemistries (Bi-polar
lead acid battery, Nickel Metal Hydride (NiMH)
battery, Lithium Ion battery) were evaluated
against the chosen parameters for selection.
To understand the energy consumption, a vehicle
simulation model (described later in Section 4)
was developed to calculate the energy consumed
on NEDC and ARTEMIS urban drive cycles.
Simulation results showed that the Axon vehicle
consumed 110 Wh/mile during the urban section
of the NEDC and 181 Wh/mile on the ARTEMIS
Urban drive cycle when operated as a full
electric vehicle. Based on these figures the
required battery capacity was determined as
2kWh for a 10mile AER to preserve battery
lifetime by limiting the depth of discharge.
Due to the small pack size requirements of the
battery, high depth of discharges in the range of
10 - 15C were required to meet the power
requirement for the ARTEMIS drive cycle. The
bi-polar lead acid chemistry was able to meet
some of these criteriasbut could not meet the 3
0
10
20
30
40
50
60
70
80
90
100
-15
-10
-5
0
5
10
15
20
VehicleSpeed(m/s)
PowerRequired(kW)
Engine/Motor power required
0
10
20
30
40
50
60
70
80
90
100
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
VehicleSpeed(m/s)
Powerrequired(kW)
Engine/Motor Power required
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
6/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
year cycle life, low weight/packaging
requirements and hence was not selected. NiMH
chemistry matched most of the requirements but
was not chosen due to high self-discharge rates
and poor availability of suppliers within the UK.
Finally, to keep the weight of the battery systemslow and to meet 3 year cycle life, Lithium-Ion
chemistry was chosen.
Within the Lithium Ion chemistry options,
Lithium Iron Phosphate (LiFePO4) was preferred
due to its superior thermal and chemical stability
as well as having a better cycle life when
compared to other Lithium chemistries such as
Lithium Cobalt Oxide (LiCoO2) or Lithium
Manganese Oxide (LiMn2O4). LiFePO4 are also
more stable under overcharging conditions and
can withstand higher temperatures without
degradation in performance. Even though the
energy density of LiFePO4 is less than LiCoO2,
LiFePO4 can support higher currents and hence
is better suited for the Axon application.
3.4. Internal combustion engine selectionBased on the power requirement calculations
shown in figures 6 and 7, the internal
combustion engine running on gasoline fuel was
selected. The engine is a twin cylinder 500cc
unit producing 26kW at 5000rpm and 40Nm at
3500 rpm. The engine is multi fuel capable and
has Start-Stop functionality. The static efficiency
map of the engine is shown in figure 8.
Figure 8: Axon60 engine efficiency map
3.5. Transmission selectionTo achieve the maximum potential from a hybrid
vehicle the engine and battery will have to
operate at peak efficiencies. In a conventional
vehicle using manual transmission, it is not
possible to keep the engine operating at the best
brake specific fuel consumption (bsfc) region
constantly. However, with a Continuously
Variable Transmission (CVT), it is possible to
operate the engine over an optimum operating
line to achieve best fuel efficiency targets. For
the Axon60 vehicle, a belt driven CVT is being
developed as the transmission. Figure 9 shows
the overall packaging of the engine, CVT and
the electric motor.
Engine Electric machine
CVT
Figure 9: Axon60 powertrain
4. Supervisory control developmentIn a hybrid electric vehicle, the fundamental
requirement of the supervisory controller is to
ensure that the driver demand is met as
efficiently as possible using a combination of the
traction sources available, i.e. gasoline engine or
electric motor.
To develop a suitable supervisory control
requires proper models of the vehicle systems.
This task was carried out using WMGs in-house
vehicle simulation software WARPSTAR
0 1000 2000 3000 4000 5000 6000 70000
5
10
15
20
25
30
35
40
45
50
Engine Speed (rpm)
Torque(Nm)
26kW Engine Map
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
7/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
which can simulate the fuel economy and CO2
emissions for various drive cycles and different
operating modes [7]. The Axon60 PHEV
architecture developed in WARPSTAR is shown
in figure 10.
Figure 10: Axon60 PHEV WARPSTAR model
The control algorithms for the Axon60 was
developed using Matlab/Simulink and Stateflow.
The Supervisory Control Unit (SCU) is the brain
of the PHEV whose main functions are to detect
the driving modes, driver inputs, sensor signals
and make appropriate decisions based on the
control logic.
A two-level control architecture shown in figure
11 was adopted for the Axon60 vehicle where
the SCU is responsible for the fuel economy and
emissions. The SCU accepts driver demands as
inputs and determines the desired output based
on current vehicle speed, battery SoC etc. These
outputs are then sent to the low level controllers
such as the engine controller and transmission
controller and become the command for the low
level controllers.
Figure 11: Axon60 controller architecture
The design of this SCU was achieved in three
steps:
i) Identification of all possible vehicleoperating states
ii) Identification of all possible transitions based on driver demand and vehicle
status
iii) Check for transition conflicts betweenstates
To generate the control logic it is important to
understand the operating modes possible with
the Axon60 architecture. Once the operating
modes of the each subsystem was identified, the
following vehicle operating modes weregenerated:
- Electric vehicle (EV) only operation- Engine only operation- Engine and electric motor assist- Engine and battery charging- Engine load levelling- Regenerative braking
The electric vehicle only operation state is
entered when the vehicle speed is less than the
EV only speed limit of 35 mph provided battery
state of charge (SoC) is greater than the
minimum battery SoC. The 35 mph cut off was
selected based on the maximum vehicle speed
observed in figures 6 & 7. Over 35 mph the
power requirements is higher than 12 kW which
will drain the battery very quickly and also these
higher speeds are more likely to be sustained for
longer periods. In this mode, the internalcombustion engine will be more appropriate than
the electric machine.
The engine only operation state is entered when
the vehicle speed is greater than the EV only
speed limit or during hard acceleration by the
driver. During this state the power required by
the engine is equal to the vehicle power demand
and the power required by the electric
motor/generator is 0 kW.
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
8/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
The engine with motor assist state is entered
when the vehicle power demand is greater than
the maximum engine power allowed. During
this state the power required by the engine is
equal to the maximum engine power allowed
and the power required by the electricmotor/generator is the remaining difference
between the vehicle power demand and the
maximum engine power. For example, if the
maximum allowed engine power is 26 kW and
the vehicle power demand is 30 kW, 4 kW will
be supplied by the electric motor, provided the
battery SoC is higher than lower SoC limit.
The engine running and battery charging
operating mode is entered when the current
battery SoC is less than or equal to the lower
SoC limit and vehicle power demand is less than
the maximum engine power allowed. For
example, if the vehicle power demand is 15 kW,
the engine has another 11 kW spare at 3500 rpm.
This 11 kW can be used to run the generator to
charge the battery. This function allows
increasing the load on engine to achieve a better
BSFC as well as charging the battery.
The engine load levelling state is entered when
the battery is at optimum charge but there is
excess torque available from the engine. In this
instance the engine is loaded by controlling the
CVT gear ratio. This allows the Axon60 to run
the engine in a more optimum operating region.
The regenerative braking state is entered when
the vehicle power demand is negative. In light
braking situations, regenerative braking will be
used. The regular friction brake is retained for
harsher braking events. After the batteries are
charged back up to maximum SoC, regenerative
braking would no longer be used. In this
situation, friction brakes would allow the driver
to achieve the required deceleration. In the case
of emergency braking, both regenerative and
conventional braking would occur, giving
maximum braking power. Otherwise only
regenerative braking would be in operation, as
long as the battery pack is not fully charged.
To maximise the use of grid energy, the vehicles
control strategy is developed to have a Charge
Depletion strategy (depending on battery SoC)
followed by a Charge Sustaining strategy.
5. Controller validation andsimulation results
Before implementing the control strategy in the
prototype vehicle, testing of the control strategy
was done using simulation methods. The
complete PHEV model was developed using
WARPSTAR and was used for simulation
testing.
5.1. Performance SimulationFrom the simulation, the power required from
the engine or motor for low speed acceleration
was estimated. The Axon60 vehicle is capable of
reaching 0-30 mph in under 6 seconds and can
reach a maximum speed of 85 mph. Figure 12
shows the power requirements of the Axonvehicle for different acceleration patterns.
Figure 12: Axon60 acceleration performance
5.2. Fuel economy predictionsThe PHEV model developed in WARPSTAR
was simulated to calculate the fuel consumption
figures for the Axon60 vehicle when using only
the ICE for propulsive power. Based on the
0 5 10 15 20 25 30 350
2
4
6
8
10
12
14
Speed (mph)
Powerrequired(kW)
Power required for acceleration from 0-30mph
5secs
6secs
7secs
8secs
9secs
10secs
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
9/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
preliminary control strategy, the Axon60 vehicle
is capable of delivering 107mpg (UK) over the
NEDC without regenerative braking. Figure 13
shows the fuel efficiency figures for three
different technology scenarios.
Figure 13: Axon60 fuel economy figures
5.3. Range testingOne of the important performance requirements
of the Axon60 PHEV is to meet the 10 mile all
electric range. A simulation was carried out for
the ARTEMIS Urban cycle to simulate the real
world usage of a PHEV. From the simulation,
the Axon60 PHEV with a 2 kWh Lithium-Ion
battery pack and 12 kW induction motor when
operated under 35 mph would meet the 10mile
AER.
Figure 14 shows the operation of the vehicle
over the ARTEMIS urban drive cycle where the
vehicle initially operates as an EV.
Figure 14: Axon60 range testing
Once the battery SoC falls below the minimum
threshold, the main propulsive force is provided
by the internal combustion engine.
5.4. Energy consumptionOver the NEDC urban section, the Axon60
vehicle consumes 110 Wh/mile when operating
in electric only mode, whereas on the ARTEMIS
urban cycle, the energy consumption is 181
Wh/mile. When operated as conventional vehicle,
i.e. engine only, the energy required is 316
Wh/mile and 494 Wh/mile respectively.
5.5. Subsystem operation mode testingThe SCU control strategy is designed to control
the CVT ratio to enable the engine operate in the
optimum operating range (shown in red circles).
The simulation results in figure 15 show that the
engine is operating in its most efficient regions.
Figure 15: Axon60 engine operating points
Also, the control strategy for Axon60 PHEV is
designed for a Charge Depleting strategy
followed by Charge Sustaining.
Figure 16 shows that the engine is in idle mode
during the all electric operation and switches on
as soon as the battery SoC falls below 0.2.
Depending on the starting coolant temperature
and battery SoC, the control strategy operates
the engine either in Offmode or in idle mode.
97
107112
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
FuelEconomy(mpg)
NEDC
0
5
10
15
Vehicle Speed (m/s)
0.2
0.4
0.6
0.8
1Battery SoC (%)
0 500 1000 1500 2000 2500 3000 35000
2
4
6
8
10
12Distance (miles)
0 1000 2000 3000 4000 5000 6000 70000
5
10
15
20
25
30
35
40
45
50
Engine Speed (rpm)
Torqu
e(Nm)
Engine operating points inNEDC gear
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
10/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
Figure 16: Axon60 engine operation in ARTEMIS
Urban
5.6. Battery management testingTo confirm whether the Axon60 vehicle is
capable of holding the battery SoC at a specified
level (Charge Sustaining strategy), a test was
carried out by repeatedly operating the vehicle in
the NEDC & ARTEMIS urban cycles. Figures
18 & 19 show how the battery SoC decreases
with range and finally reaches the lower SoC
limit of 0.2. At this stage the SCU sustains the
battery SoC and switches on the ICE.
Figure 17: Battery SoC variation in repeated NEDC
Figure 18: Battery SoC variation in ARTEMIS urban
5.7. CO2 analysisUnlike conventional hybrids, a plug-in hybrid
vehicle sources part of its energy from the
electricity grid. To achieve comparative emission
figures, WARPSTAR was extended to include
the carbon emissions from the UK electricity
grid to calculate the Well-to-Wheel (WTW)
emission figures.
Over both the NEDC urban and ARTEMIS
urban cycles, the Axon60 is predicted to have a
WTW CO2 emission less than 50 g/km (assumes
410g/kWh CO2 from UK electricity grid) [8].
This low level of emissions saves approx 1.1
tonnes of CO2 per annum for an average UK car
user when compared to conventional gasoline
cars. Table 3 shows the CO2 emissions for the
three different operating modes of the Axon60vehicle.
Table 3 : Axon60 CO2 emission figures
Drive Cycle Tailpipe
emissions
(g/km)
Wellto-Wheel
emissions
(g/km)
NEDC Urban 0 27
ARTEMIS
Urban
0 46
NEDC
(urbanEV
Extra urbanICE)
41 54
6. Prototype vehicle developmentThe Axon60 prototype vehicle in figure 20 is
undergoing further development and is expected
to complete first phase of testing by the end of
Q4 2010. The first phase of the testing will
involve crash testing the vehicle to European
Union standards and fuel economy assessments.
Figure 19: Axon60 PHEV prototype vehicle
The second stage of the testing involves
reliability and driveability assessments. The
vehicle will be used to gather important real
world data including: battery charge/discharge
characteristics, battery state of charge depletion
0 2000 4000 6000 8000 10000 12000
0
10
20
30
40
50
60
VehicleSpeed(kmph)
Time (secs)
Engine Speed inARTEMIS Urban Axon repeated
0 2000 4000 6000 8000 10000 12000
0
1000
2000
3000
4000
5000
6000
EngineSpeed(rpm)Vehicle
Mass =630
kg
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000
0.5
1
SoC(%)
Time (secs)
Battery Parameters inrepeated NEDC
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000
100
200
VehicleSpeed(kmph)
0 2000 4000 6000 8000 10000 120000
0.5
1
SoC(%)
Time (secs)
Battery Parameters inARTEMIS Urban repeated
0 2000 4000 6000 8000 10000 120000
50
100
VehicleSpeed(kmph)
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
11/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
and to validate WARPSTAR predictions. Along
with the technical developments user feedback
will be collected from customers to understand
user perception of plug-in hybrid vehicles. The
demonstrator vehicle will also be used to assess
the practicality of the electric charginginfrastructure being setup across various cities in
the UK. The results of the second phase of
testing and user feedbacks will be presented in a
future paper.
7. ConclusionIn this paper, the experiences gained during the
development of a PHEV demonstrator for the
UK market were presented. The Axon60 project
shows that considerable fuel savings and
emission reduction is possible if vehicles are
made of lightweight materials and combined
with highly efficient drivetrains. The paper also
shares the experience gained in developing the
vehicle supervisory control, component selection
and validation of control strategy for a light
weight PHEV.
8. AcknowledgementsThe authors acknowledge the support provided
by the UK Technology Strategy Board via their
Low Carbon Vehicle Innovation Platform.
9. References[1]. A.Adonis, Low Carbon Transport: A Greener
Future,Department for Transport UK, July
2009, p23
[2]. Cenex, Investigation into the Scope for theTransport Sector to Switch to Electric Vehicles
and Plug-in Hybrid Vehicles, Department for
Transport UK, 2008
[3]. H.T.Bradley, A.A.Frank, Design,demonstrations and sustainability impact
assessments for plug-in hybrid electric vehicles,
Renewable and Sustainable Energy Reviews,
Volume 13, Issue 1, January 2009, Pages 115-128
[4]. G.Muraleedharakurup, A.McGordon, J.Poxon,P.Jennings, "Building a Better Business Case: the
Use of Non-linear Growth Models for Predicting
the Market for Hybrid Vehicles in the UK",Ecologic Vehicles and Renewable Energies
Conference, Monaco, 2010
[5]. http://www.dft.gov.uk/adobepdf/163944/ulcc.pdfaccessed on 11th August 2010 (5k grant link)
[6]. P.Haan, M.Keller, M.Andre,Real-world drivingcycles for emission measurements: ARTEMIS
and Swiss cycles, Bundesamt fr Umwelt, Wald
und Landschaft (BUWAL), 2001
[7]. A.Walker, A.McGordon, G.Hannis, A.Picarelli,J.Breddy, S.Carter, A.Vinsome, P.Jennings,
M.Dempsey, M.Willows, A Novel Structure for
Comprehensive HEV Powertrain Modelling",
2006 Vehicle Powertrain and Propulsion
Conference, 2006
[8]. http://www.decc.gov.uk/en/content/cms/statistics/fuel_mix/fuel_mix.aspx accessed on 18th August
2010.
-
8/2/2019 Development of a Lightweight Plug-In Hybrid Electric Vehicle Demonstrator
12/12
EVS-25 Shenzhen, China, Nov. 5-9, 2010
The 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition
10.AuthorsMr. Girish
Muraleedharakurup
Lead Engineer
WMG, University of Warwick,Coventry, CV4 7AL, UK
Email: [email protected]
Dr.John Poxon
Research Fellow
WMG, University of Warwick,
Coventry, CV4 7AL, UK
Email: [email protected]
Dr.Andrew McGordon
Sr.Research Fellow
WMG, University of Warwick,
Coventry, CV4 7AL, UK
Email : [email protected]
Prof.Paul Jennings
WMG, University of Warwick,Coventry, CV4 7AL, UK
Email : [email protected]
Dr.Steven Cousins
Managing Director
Axon Automotive
Wellingborough,
NN29 7RL, UK
Email : [email protected]
Dr.Kevin Lindsey
Engineering Director
Axon Automotive
Wellingborough,
NN29 7RL, UK
Email : [email protected]