POLITECNICO DI TORINO Master of Science in Automotive Engineering Trade-off analysis of hybrid electric powertrains Academic Tutors: Prof. Nicola Amati Students: Prof. Andrea Tonoli Stefano Di Donato Ing. Luca Castellazzi Chowdhury Foyz Ahamed Polas
POLITECNICO DI TORINOMaster of Science in Automotive Engineering
Trade-off analysis of hybrid electric powertrains
Academic Tutors:Prof. Nicola Amati Students:Prof. Andrea Tonoli Stefano Di DonatoIng. Luca Castellazzi Chowdhury Foyz Ahamed Polas
Hybrid electric vehicles
• High pollutant emissions
• Global warming
• Increase of fossil fuel price
Introduction
2/25
Tighter regulations on vehicle emissions
Architectures
Hybrid Electric Vehicles (HEV)
Series
Power split (Series-Parallel)
Parallel
3/25
4/25
Hybrid Electric Vehicles (HEV)
Hybridization Ratio
FrontDifferentia
l
5/25
Modelled architectures• Through The Road (TTR)
Gearbox Cl
utc
h
Fuel
Internal Combustion Engine
Electric Machine/Inverter
48V Battery
Front Wheels
RearDifferentia
l
Rear Wheels
Differential
6/25
Modelled architectures• Belt-driven Starter Generator (BSG)
Gearbox Cl
utc
h
Fuel
Internal Combustion Engine
Electric Machine/Inverter
48V Battery
Front Wheels
Belt Coupling
• Modelling and analysis of hybrid powertrains
• Energetic analysis, battery sizing
• Accessories energy consumption
• Comparison between different architectures
7/25
Objectives
8/25
Vehicle DataModelled vehicle: Fiat Panda
Internal combustion engine: 1.0 TwinAir (Naturally Aspirated)• Max Power: 65CV @6250 RPM• Max Torque: 88Nm @3500 RPM
Vehicle mass: 975 Kg
Wheelbase: 2.3 m
Powertrain components (Pure ICE Vehicle)
9/25
Vehicle Model
Driving Cycle
Driver
Internal Combustion Engine
Clut
ch Gearbo
xDifferenti
al Wheels
Drivetrain
Ref. Speed
Actual Speed
Throttle Torque
Longitudinal Wheel Force (Fx)
Brakes
Fuel Consumption
Vehicle Dynamics
Fuel Consumption Evaluation
10/25
Vehicle Model
𝑝𝑚𝑒=𝑇 𝑛𝑐
10𝑉 𝑑2𝜋
- : mean effective pressure- : Instantaneous torque- : Number of revolutions per power
stroke (for a 4-stroke engine = 2),- : the displacement volume
g/CVh
g/CVh kg/J kg/s l/100km
11/25
Validation of the model
Modelled vehicle Real vehicle
0-100 km/h acceleration test 15.28 s 15.7 s
Fuel Consumption comparison (NEDC) 4.4 l/100km 4.2 l/100km
BSG ImplementationVehicle Model
Internal Combustion Engine Belt
Coupling
- Belt Drive System Block (BDS)Pulleys• Alternator/EM • A/C compressor• Automatic Tensioner• Crankshaft• Idle
12/25
48V Battery Electric Machine/Inverter
Modelled phenomena• Predict levels of slip in different pulley-
belt contact regions• Calculate the belt tensions for different
spans• Calculate power losses of the system
- Electric motor
Battery ModelVehicle Model
13/25
𝐸=𝐸0−𝐾 ( 𝑄𝑛𝑜𝑚
𝑄𝑛𝑜𝑚−𝑄 )+ 𝐴𝑒−𝐵𝑄
𝑆𝑂𝐶 [%]=100 (1− 𝑄𝑄𝑛𝑜𝑚 )
- = no-load voltage [V]- = battery nominal voltage [V]- = polarization voltage [V] - is the actual battery charge [Ah],- is the nominal battery capacity [Ah], - is the exponential zone amplitude [V],- is the exponential zone time constant inverse [Ah-1]
TTR Implementation
14/25
Vehicle Model
Electric Machine/Inverter
48V Battery
RearDifferentia
l
• The BDS system is removed from the front driveline.
• A seperate 3 phase Brushless AC Motor powers the rear axle.
• The motor can generate maximum torque of 88 Nm and peak power 30 kW.
• Current absorption characteristics of the Electric Motor.
15/25
Vehicle Model (TTR)
16
• Modelled as a one-dimensional linear model
• = Dissipated Power
• = Thermal resistance
• = Thermal time constant
Thermal Model
𝑡
𝑇 𝐸𝑀𝑃 𝐷𝑅 h𝑡
𝜏 h𝑡
17/25
Control Strategy• Control parameters
• Battrey SOC%,
• Current,
• Temperature.
• Controlled parameters• Torque provided by the ICE,
• Torque provided by the EM.
• Control Objectives
• Obtain battery energy balance,
• Regeneration of maximum brake energy,
• Safety,
• Fuel consumption reduction.
18/25
Control StrategyCurrent control SOC control Temperature control
19/25
Validation of the Control strategy• NEDC cycle
• Battery capacity 35Ah
• Maximum current 175 A
• Initial SOC = 70%
• = 30 km/h
• Simulations varying Vswitch : ∆SOC evaluation
• Fuel consumption evaluation for each capacity
(Energetic equilibrium -> ∆SOC = 0)
• Battery sizing
• Comparison between BSG and TTR configurations
20/25
Battery Sizing
• A part of battery energy is required by the electrified accessories,
• For example an electrified A/C compressor require a power of 1500W,
• The energy from the regenerative braking is not sufficient,
• A BSG or a conventional alternator will provide the necessary power.
21/25
Electrified AccessoriesCapacity 17.5Ah @10C
BSG Model TTR Model
Available Current 12.19 A 23.5 A
Available Power 585 W 1130 W
Capacity 17.5Ah @10C
Belted A/C Compressor
Electric A/C Compressor
Fuel Consumption
5.265 l/100km
5.072 l/100km
• All the simulations are repeated for the TTR architecture,
• The TTR configuration consumes 12.5% less than the BSG.
22/25
Electrified AccessoriesCapacity 17.5Ah @10C
BSG Model TTR Model
Applied torque (BSG or Alternator)
3.05 Nm 1.1 Nm
Available Power 1500 W 1500 W
Fuel consumption
5.072 l/100km
4.44 l/100km
Vehicle configuration BSG Model TTR Model ImprovementPure ICE 4.173 4.173
Hybrid (Battery 17.5 Ah @10C) 3.833 3.260 14.95%
Hybrid (Battery 17.5 Ah @10C)With electric A/C compressor (1500W)
5.072 4.440 12.45%
23/25
Review of the results
• The TTR architecture is more efficient for electric traction and regenerative braking.
• The BSG architecture is useful to generate power for the accessories and as starter motor
• The optimal configuration can be a combination of the two architectures
24/25
Conclusions
FrontDifferentia
l
25/25
Conclusions• Optimal architecture
Gearbox Cl
utc
h
Internal Combustion Engine
Electric Machine/Inverter
48V Battery
Front Wheels
RearDifferentia
l
Rear WheelsBSG Machine/Inverter
Electrified Accessorie
s
Thank You for
Your Attention