48V Hybridization Of A Mid Size Vehicle Using Electric Motor And Electric Assisted Supercharger
AbstractIn a context of growing demand for sustainable transportation worldwide, different technical solutions for hybridvehicles are nowadays investigated as effective ways to improve efficiency of the driveline and thus to reduce CO2
emissions. As a matter of fact, the CO2 emission targets set by EU (95 g/km in 2020 and 75 g/km in 2025) areextremely demanding.
In order to reach the 2020 CO2 emission target with a spark ignition engine, solutions needs to be developed(hybridization) or reinforced (downsizing). At the same time, no compromise should be done between fuelconsumption and fun-to-drive. While turbocharged engines exhibit poor transient performance (“turbo lag”), anelectric supercharger allows improving fuel consumption, turbo lag and increasing engine torque at low speed.
The subject of this study is to present a cost effective solution package for a gasoline engine, achieving lower CO2
emissions compared to a state of the art Diesel engine without compromising fun to drive.
Target• Baseline: Golf VII 1.6L TDI, a state-of-the-art conventional diesel vehicle.
• Target those kind of CO2 figures with a mild-hybrid vehicle (48 Volt) powered by a turbocharged gasoline engine
and equipped with a manual transmission.
• Provide better driving performance (fun-to-drive) by adopting an electric-assisted supercharger (eSC).
Hybrid Architecture Selection
Benchmark (C-segment)
Results
Conclusion• Through Mild Hybridization (48V) it has been possible to achieve considerable CO2 benefit regarding conventional
gasoline and meet the 95 gCO2/km target.
• Thanks to the E-Machine (15kW) and electric supercharger (4kW) (especially at low and mid load) the fuelimprovement is not at the expense of the fun-to-drive.
AcknowledgementSpecial thanks go to Mr Sebastien Potteau from Valeo and Mr Prakash Dewangan from IFP School for their
continuous support and availability.
Curb Weight
(kg)
Power
(hp)
Torque(Nm)
Maximum speed (km/h)
80-120 km/h (s)
30-60 km/h (s)
NEDC FC (L/100km)
CO2 (g/km)
1295 105 250 192 11,6 6,7 3,9 99
MMT
D
MT
DM
MMT
DMT
D M
e-Supercharger Implementation
Gear Selection Optimization
Pros: Limited extra-weight.Cons: No regenerative braking when clutch disengaged,Undergoes engine resistive torque when running FullElectric or regenerating during braking.
Pros: E-Machine can be totally decoupled from engine.Cons: Additional clutch (limited space for transverseengine).
Pros: Double shaft suitable with transverse engine,Regenerative braking with engine totally decoupled.Cons: Additional transmission ratio (weight).
P1
P2
P3 P4
0
1
2
3
4
5
65,38 5,09
(-5,4%)4,03
(-25,1%) 3,52(-34,6%)
4,13(-23,2%) 3,90
(-27,5%)
Fue
l Co
nsu
mp
tio
n (
L/1
00
km)
FUEL CONSUMPTION (L/100KM)
As the C-segment cars usually adopt atransverse engine the P3 architecturehas been preferred with a gear ratio of3 to ensure the CO2 target.
Assumptions: Imposed gear shifting, ideal Stop &Start, E-Machine (15 kW) not used for cranking and allthe braking torque can be recovered by the E-Machine.
Assumptions: Stop & Start disabled during the first 150s to warm up the engine.
Gear Shifting Strategy (Manual Transmission) :• When vehicle speed is constant or increase a gear
has to be engaged (safety).• When decelerating shift to neutral to recover the
max energy.• E-machine (15kW) ensures take off.• A fuel penalty is added to a gear shifting.
0
50
100
150
0
1
2
3
4
5
0 200 400 600 800 1000 Ve
hic
le s
pe
ed
(km
/h)
Ge
ars
Time (s)
Gear ShiftingOptimal Gear Shifting Fixed Gear Shifting Vehicle speed
0
20
40
60
80
100
120
0 1000 2000 3000
Veh
icle
sp
eed
(km
/h)
Time (s)
Cycles
NEDC RDE
Real Driving Emissions in Paris
110
79
4,6
3,3
0
1
2
3
4
5
6
0
20
40
60
80
100
120
140
Fuel
Co
nsu
mp
tio
n (
L/1
00
km)
CO
2(g
/km
)
RDE Cycle
-28,2%
Fuel Consumption NEDC: 3,72L/100km (2,8% Fuel Saving)
0
50
100
150
200
250
500 1500 2500 3500
Torq
ue
(Nm
)
Engine RPM
Engine operating point evolution of 60-100km/h acceleration
e-Supercharger
Turbocharger
Max Torque [Nm]
• Electric-assisted supercharger is able to considerably reduce the time to torque, thusincreases the fun-to-drive of a vehicle. Improvement could reach more than 10%.
• This improvement is especially interesting when the engine is running at low RPM.
• E-motor is another good enabler of better acceleration performance, but requiresrapid depletion of the battery capacity.
Cost Calculation Gas Hybrid Diesel
Tax (€/year) 1000 1475
Maintenance (€/year) 900 1000
Fuel consumption (€/year) 605 560
Total cost (€/5years) 12525 15175
(2650€/5years Savings)
129
99 89
5,4
3,8 3,7
0
1
2
3
4
5
6
020406080
100120140
Fuel
Co
nsu
mp
tio
n (
L/1
00
km)
CO
2(g
/km
)
NEDC Cycle
-31,0%
Conventional Gasoline
Diesel Golf VII
14,0113,42
14,0513,46
12,42 12,70
9,82
8,88
5,97
9,46
8,30
5,525,06,07,08,09,0
10,011,012,013,014,015,0
80-120km/h 60-100km/h 30-60km/h
Du
rati
on
(s)
Range Of Roll-on Acceleration On 5th Gear
Roll-on performance of vehicles with/without an e-supercharger (4kW)
TC w/o EM eSC w/o EM TC w/i EM eSC w/i EM
Final Architecture
Conventional Gasoline
Final Architecture
Team Members: Thomas REDLINGER, Shixiong ZHAO, Aggelos ZOUFIOS, Stanish GUNASEKARAN
0
1
2
3
4
5
6
DIESEL GASOLINE HYBRID
Fue
l Co
nsu
mp
tio
n (
L/1
00
km)
Fuel Consumption and CO2 Emissions
3,9 4,0 4,8 5,0 5,43,2 3,8 3,4 4,4
99
84
104
110 114
124
8488
101
Diesel Gasoline Hybrid
AGolf VII1.6 TDI
Peugeot 308 II 1.2 THP
Toyota Auris136h
BPeugeot 308 Blue HDI 120
Ford Focus III 1.0 Ecoboost
Peugeot 3008
Hybrid4
CAlpha Romeo Giullietta 1.6 JTDM-2 105
Renault Mégane Energy TCe 130
Honda Insight II
-10,1%
A C A B CB A B C
Assumptions Gas Hybrid Diesel
Mean distance in France (km/year) 12 700 12 700
Ownership duration (year) 5 5
Fuel rate (€/L) (Super 98) 1.28 1.17
Fuel consumption (L/100km) 3.72 3.9
Additional components:
• E-Supercharger (4kW)
• E-motor (15 kW)
• Battery pack (48V)
• DC/DC converter
• Cables
Comparison: Proposed Hybrid vs. Conventional Gasoline vs. State of Art Diesel (Golf VI 1.6TSI)Weight Increase + 43 kg + 3 kgAdditional Cost + 1285 € (*) + 285 € (*)CO2 Benefit 40 g/km 10 g/kmCO2 Reduction Cost 32,1 €/gCO2/km 28.5 €/gCO2/km
Cycle Definition
Fuel Consumption & CO2 Emission
System Overview
Total Cost of Ownership Estimation
Additional Weight and Cost Estimation
(*) : Indicative Market Price for 2020 for mass production (> 200 000 pieces / year)
Engine Selection & OptimizationIC Engine
1,6L 4 cylinders Turbocharged
Max Torque [Nm/L]
170,9
Max Power [KW/L]
67,3
Specific TorqueEngine Downsized to 1,2L
Improving Fuel Consumption
Heat losses proportionalto the available surfacearea
𝑸 = 𝒉 ∗ 𝑨 ∗ (𝑻𝒈 − 𝑻𝒘𝒂𝒍𝒍)
3 cylinders implementation
3-cyclinders ImplementationAssumptions:
S/B ratio for conventional gasoline engines = 0,8
Exhaust gas losses = 30 % of the fuel energy
Constant mean wall temperature and BMEP
9,15 % reduction in heat transfer area
2,75% gain in fuel consumption
Diesel Golf VII
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