Vehicle Propulsion Systems Lecture 4 Hybrid Powertrains, Topologies and Component Modeling Lars Eriksson Professor Vehicular Systems Link ¨ oping University March 26, 2017 2 / 64 Outline Repetition Introduction to Hybrid-Electric Vehicles Potential Electric Propulsion Systems Overview of Hybrid Electric Configurations Series Hybrid Parallel Hybrid Combined Hybrid Electric motors, Generators Modeling Batteries, Super Capacitors Transfer of Power Power Links Torque Couplers Power Split Devices Extra Material Implemented concepts 3 / 64 The Vehicle Motion Equation Newtons second law for a vehicle m v d dt v (t )= F t (t ) - (F a (t )+ F r (t )+ F g (t )+ F d (t )) Ft Fr Fa Fd α mv · g Fg I F t – tractive force I F a – aerodynamic drag force I F r – rolling resistance force I F g – gravitational force I F d – disturbance force 4 / 64 Energy consumption for cycles Numerical values for MVEG-95, ECE, EUDC air drag = 1 xtot X i ∈trac ¯ v 3 i h = {319, 82.9, 455} rolling resistance = 1 xtot X i ∈trac ¯ vi h = {.856, 0.81, 0.88} kinetic energy = 1 xtot X i ∈trac ¯ ai ¯ vi h = {0.101, 0.126, 0.086} ¯ EMVEG-95 ≈ Af cd 1.9· 10 4 +mv cr 8.4· 10 2 +mv 10 kJ/100km 5 / 64 Engine Efficiency Maps Measured engine efficiency map – Used very often –Willans line approximation. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -5 0 5 10 15 20 BMEP [bar] Intake manifold pressure [bar] model measurement 6 / 64 Model implemented in QSS Conventional powertrain. Efficient computations are important –For example if we want to do optimization and sensitivity studies. 7 / 64 Outline Repetition Introduction to Hybrid-Electric Vehicles Potential Electric Propulsion Systems Overview of Hybrid Electric Configurations Series Hybrid Parallel Hybrid Combined Hybrid Electric motors, Generators Modeling Batteries, Super Capacitors Transfer of Power Power Links Torque Couplers Power Split Devices Extra Material Implemented concepts 8 / 64 Definition What characterizes a Hybrid-Electric Vehicle I Energy carrier is a fossil-fuel. I Presence of an electrochemical or electrostatic energy storage system. 9 / 64
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Vehicle Propulsion SystemsLecture 4
Hybrid Powertrains, Topologies and Component Modeling
Lars ErikssonProfessor
Vehicular SystemsLinkoping University
March 26, 2017
2 / 64
OutlineRepetitionIntroduction to Hybrid-Electric Vehicles
PotentialElectric Propulsion Systems
Overview of Hybrid Electric ConfigurationsSeries HybridParallel HybridCombined Hybrid
Electric motors, GeneratorsModeling
Batteries, Super CapacitorsTransfer of Power
Power LinksTorque CouplersPower Split Devices
Extra MaterialImplemented concepts
3 / 64
The Vehicle Motion EquationNewtons second law for a vehicle
mvddt
v(t) = Ft (t)− (Fa(t) + Fr (t) + Fg(t) + Fd (t))
Ft
Fr
Fa
Fd
α
mv · g
Fg
I Ft – tractive forceI Fa – aerodynamic drag forceI Fr – rolling resistance forceI Fg – gravitational forceI Fd – disturbance force
4 / 64
Energy consumption for cycles
Numerical values for MVEG-95, ECE, EUDC
air drag =1
xtot
∑i∈trac
v3i h = {319,82.9,455}
rolling resistance =1
xtot
∑i∈trac
vi h = {.856,0.81,0.88}
kinetic energy =1
xtot
∑i∈trac
ai vi h = {0.101,0.126,0.086}
EMVEG-95 ≈ Af cd 1.9 ·104 +mv cr 8.4 ·102 +mv 10 kJ/100km
5 / 64
Engine Efficiency MapsMeasured engine efficiency map – Used very often
–Willans line approximation.
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2−5
0
5
10
15
20
BM
EP
[bar
]
Intake manifold pressure [bar]
modelmeasurement
6 / 64
Model implemented in QSS
Conventional powertrain.
Efficient computations are important–For example if we want to do optimization and sensitivitystudies.
7 / 64
OutlineRepetitionIntroduction to Hybrid-Electric Vehicles
PotentialElectric Propulsion Systems
Overview of Hybrid Electric ConfigurationsSeries HybridParallel HybridCombined Hybrid
Electric motors, GeneratorsModeling
Batteries, Super CapacitorsTransfer of Power
Power LinksTorque CouplersPower Split Devices
Extra MaterialImplemented concepts
8 / 64
Definition
What characterizes a Hybrid-Electric VehicleI Energy carrier is a fossil-fuel.I Presence of an electrochemical or electrostatic energy
storage system.
9 / 64
Potential for Energy Savings
Benefits of Hybrid-Electric VehiclesI Downsize engine while maintaining maximum power
requirementI Recover energy during deceleration (recuperation)I Optimize energy distribution between prime moversI Eliminate idle fuel consumption by turning off the engine
(stop-and-go)I Eliminate the clutching losses by engaging the engine only
when the speeds matchPossible improvements are counteracted by a 10-30% increasein weight.
10 / 64
Electric Vehicles
I Basic topology
I Sketch of the paths
P M TB V
Electric vehicle
11 / 64
Electric Vehicles
I Contain basic elements of HEV.I Not “interesting”, for optimization.
–No in-depth coverage in the course.I Interesting from the design point of view.I Drawbacks compared to a conventional vehicle
I Not autonomousI Refueling timeI Low range/weight
I ⇒ Niche vehiclesI Plug-in EV:s are hot in mediaI Development of plug-less vehicles
–Inductive chargingI Range extenders (transition to series hybrid)
12 / 64
Electric Vehicles – From Niche to PublicI Applications requiring zero-emissions.
I Indoor vehicles, mines . . .I In-city distribution vehiclesI Zero emission vehicle requirements
I Other niched vehicles
Lightning Tesla RoadsterI Nissan Leaf, Volvo C30 Electric
13 / 64
OutlineRepetitionIntroduction to Hybrid-Electric Vehicles
PotentialElectric Propulsion Systems
Overview of Hybrid Electric ConfigurationsSeries HybridParallel HybridCombined Hybrid
Electric motors, GeneratorsModeling
Batteries, Super CapacitorsTransfer of Power
Power LinksTorque CouplersPower Split Devices
Extra MaterialImplemented concepts
14 / 64
Basic configurations
Basic classification of hybridsI Series hybridI Parallel hybridI Series-parallel or combined hybrid
There are additional types that can not be classified into thesethree basic types
I Complex hybrid (sometimes)
15 / 64
Series Hybrid – Topology
Sketch of the topology
P M TB V
G
E
Basic Series Hybrid
16 / 64
Series Hybrid
17 / 64
Series Hybrid – Modes and Power FlowsThe different modes for a series hybrid
u ≈ Pbatt/Pvehicle
Battery drive mode
P M TB V
G
ESeries Hybrid
Battery drive mode, u=1
Battery recharge mode
P M TB V
G
ESeries Hybrid
Battery recharge mode, u<0
Hybrid drive mode
P M TB V
G
ESeries Hybrid
Hybrid drive mode, 0<u<1
Regenerative braking mode
P M TB V
G
ESeries Hybrid
Regenerative braking mode, u=1
18 / 64
Parallel Hybrid – Topology
Sketch of the topology
P M TB V
EBasic Parallel Hybrid
19 / 64
Parallel Hybrid – Topology
20 / 64
Parallel Hybrid – Modes and Power FlowsThe different modes for a parallel hybrid
u ≈ Pbatt/Pvehicle
Battery drive mode (ZEV)
P M TB V
E
Parallel Hybrid
ZEV mode, u=1
Battery recharge mode
P M TB V
E
Parallel Hybrid
Battery recharging mode, u<0
Power assist mode
P M TB V
E
Parallel Hybrid
Power assist mode, 0<u<1
Regenerative braking mode
P M TB V
E
Parallel Hybrid
Regenerative braking mode, u=1
Conventional vehicle
P M TB V
E
Parallel Hybrid
Conventional vehicle mode, u=0
21 / 64
Mild Parallel Hybrid – Topology
Sketch of the topology
M T VEPB
Mild Parallel Hybrid
22 / 64
Combined Hybrid – Topology
Sketch of the topology
MPB
G T V
E
PG
Combined Hybrid
23 / 64
Combined Hybrid – Topology
24 / 64
Combined Hybrid with PGS – Modes and Power FlowsThe different modes for a combined hybridConventional vehicle–Note the loop
MPB
G T V
E
PG
Combined Hybrid
Engine only mode
Power assist mode–Note the loop
MPB
G T V
E
PG
Combined Hybrid
Power assist mode
Battery drive mode (ZEV)
MPB
G T V
E
PG
Combined Hybrid
ZEV mode
Battery recharge mode
MPB
G T V
E
PG
Combined Hybrid
Battery recharging mode
Regenerative braking mode
MPB
G T V
E
PG
Combined Hybrid
Regenerative braking mode
25 / 64
Combined Hybrid Without Planetary Gear
MPB
E
T V
GCombined Hybrid
26 / 64
Degree of Hybridization
I Degree of hybridization–The ratio between electric motor power and engine power.
I Implemented hybrid concepts in carsDegree of hybridization varying between 15–55%
I True mild hybrid conceptsDegree of hybridization varying 2–15%
27 / 64
Summary of different hybrid concepts
Feature Conv. Micro Mild Full Plug-inShut of engine at stop-lights and stop-go traffic (x) X X XRegenerative braking and operates above 42 V X X XElectric motor to assist a conventional engine X X XCan drive at times using only the electric motor X XRecharges batteries using the wall plug with at least 32 km rangeon electricity
X
28 / 64
State Of Charge – SOC
I Charge condition for the battery.I Full range SOC ∈ 0–100%.I Used range SOC ∈ 50–70%.I Generally difficult problem
Models that include aging are not (yet) good enough.
AC motors (compared to DC motors)Less expensive but more sophisticated control electronics, gives higheroverall cost.Higher power density, higher efficiency.
AC motors (permanent magnet vs induction motors)Averaged values from Advisor database.
I Can also define an instantaneous efficiency.54 / 64
Efficiency definition – Instantaneous
55 / 64
SupercapacitorsI Supercapacitors and ultracapacitorsI High power density
–Used as short time scale energy buffer.–Load leveling to the battery.
I Very similar to battery in modelingExchange the battery for a capacitor in the circuit below.
U2
Ri
I2
Uoc
C
Uoc(t) =Q(t)
C=
1C
∫I(t)dt
I Efficiency definitionsPeukert and Ragone
56 / 64
OutlineRepetitionIntroduction to Hybrid-Electric Vehicles
PotentialElectric Propulsion Systems
Overview of Hybrid Electric ConfigurationsSeries HybridParallel HybridCombined Hybrid
Electric motors, GeneratorsModeling
Batteries, Super CapacitorsTransfer of Power
Power LinksTorque CouplersPower Split Devices
Extra MaterialImplemented concepts
57 / 64
Power Links
I Electrical glue componentsI DC-DC convertersI DC-AC converter
I Account for power losses
58 / 64
Torque couplers
I Components that are included to:I Glue for mechanical systems acting on the same shaft
I Can include:I Gears in the coupling equationI Sub models for friction losses
I Basic equations–Angular velocities–Torque (from a power balance, including losses)
59 / 64
Power Split DevicesI Manage power splits between different componentsI Important component for achieving flexibilityI Modeling approach: Speed relations with torque from
power balance.
Can add more planetary gears60 / 64
OutlineRepetitionIntroduction to Hybrid-Electric Vehicles
PotentialElectric Propulsion Systems
Overview of Hybrid Electric ConfigurationsSeries HybridParallel HybridCombined Hybrid
Electric motors, GeneratorsModeling
Batteries, Super CapacitorsTransfer of Power
Power LinksTorque CouplersPower Split Devices
Extra MaterialImplemented concepts
61 / 64
Implemented concepts
I Passenger carsI Parallel hybridsI Combined hybridsI Very few series hybrids (range extenders to EV).
I Trucks and bussesI Series hybridsI Parallel hybridsI Combined hybrids
I Diesel trains– Series configuration but no storage
62 / 64
’08 List of Hybrid Passenger Cars (Incomplete)I Chevrolet Silverado Hybrid Truck, Chevrolet Tahoe HybridI Daihatsu HighjetI Ford Escape, Ford Mercury Mariner HybridI GMC Sierra Hybrid Truck, GMC Yukon HybridI Highlander HybridI Honda Accord Hybrid, Honda Civic Hybrid, Honda Insight
HybridI Landrover HybridI Lexus GS450h, Lexus RX 400hI Nissan AltimaI Porsche Cayenne HybridI Saturn VUE Greenline HybridI Suzuki TwinI Toyota Alphard Hybrid, Toyota Camry, Toyota Estima