Hybrid Drive Systems for Vehicles - IEA - Lund University
Transcript of Hybrid Drive Systems for Vehicles - IEA - Lund University
Hybrid Drive Systems for Vehicles• L4
– Alternative drive train Components
© Mats Alaküla EHS
Drawback with conventional drivetrains• Limited ability to optimize
operating point
• No ability to regenerate braking power
© Mats Alaküla EHS
Solutions• Smaller Engine
+ Reach higher operating points- Still cannot regenerate
• Store energy in the vehicle mass- Speed variations- Still cannot regenerate
• Secondary energy storage+ Selectable operating point (Pstorage
= Pice – Proad)
+ Can regererate- Expensive
© Mats Alaküla EHS
Smaller Engine – cylinder deactivation
© Mats Alaküla EHS
IC E EM
PEBatt
GEARClutch
DIFFIC E Clutch
0 200 400 6000
50
100
150
0 200 400 6000
50
100
150
0 200 400 6000
50
100
150
Combustion On Demand• Cylinder deactivation via free
valve control
• 4-stroke, 6-stroke, 8-stroke ...
© Mats Alaküla EHS
Optimized efficiency
0200
400600
020
40
6080
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Speed [rad/s]Torque [Nm] 0200
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Speed [rad/s]Torque [Nm] 0200
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Speed [rad/s]
Number of Cylinders in use
Torque [Nm]
© Mats Alaküla EHS
Max efficiency
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 104
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0.35
ICE Power [W]
Opt
imal
Effi
cien
cy
Blue=2-cylinder std, Red=2-cylinder COD
© Mats Alaküla EHS
Secondary Energy Storage selection• Why electric?
– Efficient secondary energy converters (Electrical machines)
– Safe, quiet, flexible installation– Increasing need for Auxilliary electric
power– High torque density of Electrical
Mchines• Up to 30 Nm/kg• ICE: <2 Nm/kg
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Secondary energy storage – Hybridisation
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Energy Storage Systems
Industrial Electrical Engineering and Automation
How does a battery look?
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Design criteria
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Cost
OperationPerformance
Vehicle
Driving the Hybrid by the Atoms
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Source: Uppsala University
Technologies
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NiMHNiMH
Li-ionLi-ion S.C.S.C.
LeadLead
Limiting Factors
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NiMHNiMHDurabilityWeightCost
Li-ionLi-ionCostSafety S.C.S.C.Energy
Initial Cost
LeadLeadCharge PowerDurability
WeightMaintenance
Performance
© Mats Alaküla EHS
Pb-Acid
NiMH
Li-ion
Pow
er D
ensi
ty
Energy Density
S.C
Effpower
Battery Cell Properties
© Mats Alaküla EHS
• All parameters are non-linear• Strong dependence on SOC,
temperature, current rate & direction, and history.
• OSV = Open Circuit Voltage• R0, R1, C1 describe the battery
resistance, charger transfer and “double layer effect”1
• R2, C2 describe the diffusion2 effect1) The first layer, the surface charge (either positive or
negative), consists of ions adsorbed onto the object due to chemical interactions. The second layer is composed of ions attracted to the surface charge via the Coulomb force, electrically screening the first layer. https://en.wikipedia.org/wiki/Double_layer_(surface_science)
2) Movement of Lithium ions
https://www.sciencedirect.com/science/article/pii/S0360544217317127#fig1
http://www.mdpi.com/1996-1073/9/6/444
Super Capacitor Cell PropertiesRohm = f(T, ω)
C = f(U, T, ω)
Terminal Voltage
+
-
Rleak = f(T)
L = f(T, ω)
Losses
© Mats Alaküla EHS
– Fewer non-linear elements– Strong dependance on SOC & temperature only
”Semi” Steady-State Operation!
Combined Energy Storage System
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SuperCaps
Ener
gy D
ensi
ty
Power Density
Combined SystemBattery
Driving Criteria Power output/regeneration at a specific time Charge and Discharge Properties Cooling Issues Pure Electric Range Upcoming energy need (GPS, weather and traffic
info, etc.)
Factors Determined by:State of Function = State of Charge + State of Health
© Mats Alaküla EHS
State of Charge
© Mats Alaküla EHS
Volta
ge
100% State of Charge 0%
Li-ion
NiMHS.C.
https://www.researchgate.net/figure/Discharge-curves-for-different-technologies-and-different-batteries_fig1_224395476
• C-rate = P[kW] / W[kWh]– C=1: 1 h full charge– C=2: 30 min full charge
State of Health• Temperature and Temperature Changes• Charge and Discharge Properties• Pure Electric Range• State of Charge• 200 - 500 individual cells in a battery
system– ALL need to be managed
• Management unit is needed– BMU (Battery Management Unit)
© Mats Alaküla EHS
SAFT data
© Mats Alaküla EHS© Mats Alaküla
SAFT Lithium teknologi
© Mats Alaküla EHS© Mats Alaküla
Battery Lifetime : II• Calculate the total converted
energy as:Wconv=Wbatt*DoD/100*NoC
• And the battery cost per kWh converted energy as:SEKperkWh = CostPerkWh*Wbatt /
WconvCostPerkWh = 3000 [SEK]
Battery Lifetime : III
• Note! – The total converted energy falls fast with increased DoD !!!
• The cost per converted kWh increases rapidly with increased DoD
0 2 0 4 0 6 0 8 0 1 0 01 0 3
1 0 4
1 0 5
1 0 6
NoC
D e p th O f D is c h a rg e [% ]
0 2 0 4 0 6 0 8 0 1 0 01 0 0
1 0 1
1 0 2
1 0 3
D e p th O f D is c h a rg e [% ]
Con
verte
d E
nerg
y [M
Wh]
0 2 0 4 0 6 0 8 0 1 0 00
0 .5
1
1 .5
2
D e p th O f D is c h a rg e [% ]
Cos
t[SE
K/k
Wh]
Battery Lifetime : IV
1002,
batt
avech
W
tPDoD
• Assume that DoD is driven by a constant charge Power
• then… :
DoD
SOC
Pcharge Pch,ave
0 t
0
5
1 0
1 5
2 00 2 0 4 0 6 0 8 0 1 0 0
0
2
4
6
8
1 0
1 2
D o D [% ]
B a t te ry L ife t im e in Y e a rs , u s e d 8 h /d a y , 3 0 0 d a y s /y e a r
P c h ,a ve /W b a t t [ 1 /h ]
[yea
rs]
Battery Lifetime : V
NoC
WPDoD
NoCP
WDoDLifetime
W
tPDoD
batt
avech
avech
batt
batt
avech
100
2100
2
1002
,
,
,
• The battery lifetime can be calculated as:
• Now, plot the battery lifetime as a function of DoD and (Pch,ave/Wbatt)– Assume 8h/day, 300 days/year
Battery Lifetime: Conclusions• Deep discharge of a
battery costs lifetime– Best with less than 10 % DoD
• The battery may have a high power density BUT using it is expensive, i.e. a high power/energy ratio costs lifetime– Best with an average battery
power in the range 3…4 x the battery energy capacity.
Other technologies?Material Average Voltage Gravimetric Capacity
LiCoO2 3.7 V 140 mAh/g
LiMnO2 4.0 V 100 mAh/g
LiFePO4 3.3 V 120 mAh/g
Li2FePO4F 3.6 V 115 mAh/g
• Lithium batteries comes in a number of siblings– Lithium-Manganese Oxide or– Lithium Nickel Oxide or– Lithium Cobolt Oxide or– Lithium Iron Phosphate
• Most of these are considered thermally unsafe since the oxygen is easily released in case of cell abuse
• The only alternative, up to now, that is considered thermally stable is– Lithium Iron Phosphate– Watch :– http://www.valence.com/why-
valence/safety
Toshiba SCiB ?• New Lithium chemistry?• Toshiba calls it SCiB• Claims 90 % recharge in 5 minutes
and 5000 Cycles life• 90 % in 5 minutes means
(0.9/(5/60)) = 10.8 in Power/EnergyCapacity ratio.– A 10 kWh battery would be possible
to recharge with 108 kW charging power without damage …
• 2.4*4.2/1000/0.150 = 0.0672 kWh/kg … normal
Nominal Voltage 2.4 V
Nominal Capacity 4.2 Ah
Size Approx. 62 x 95 x 13mm
Weight Approx. 150 g
Toshiba vs LiFePo …
05
1 01 5
2 0 02 0
4 06 0
8 01 0 0
0
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1 0
1 5
2 0
2 5
D o D [% ]
B a t te ry L ife t im e in Y e a rs , u s e d 8 h /d a y , 3 0 0 d a y s /y e a r
P c h ,a ve /W b a t t [ 1 /h ][y
ears
]
0 2 0 4 0 6 0 8 0 1 0 01 0
2
1 0 4
1 0 6
1 0 8
NoC
D e p th O f D is c h a rg e [% ]
0 2 0 4 0 6 0 8 0 1 0 01 0 0
1 0 1
1 0 2
1 03
D e p th O f D is c h a rg e [% ]
Con
verte
d E
nerg
y [M
Wh]
0 2 0 4 0 6 0 8 0 1 0 00
0 .5
1
1 .5
2
D e p th O f D is c h a rg e [% ]
Cos
t[SE
K/k
Wh]
Battery simulation model : I
© Mats Alaküla EHS
b a t ti
b a t te
b a ttR
ec hP a rg te rmP
lo s sP
term
echbatt
losstermech
battbattloss
batt
term
batt
batt
batt
battbatt
battbattbattbattbattbattbattbattterm
PP
PPPiRP
RP
Re
Rei
iRieiiReP
arg
arg
2
2
2
22
)(
Battery Simulation model : II
© Mats Alaküla EHS
- 1 - 0 .5 0 0 .5 1
x 105
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2B a tte r y c h ar g e e f f ic ie n c y
B at te ry p o we r [ W ]
Effic
ienc
y
Super Capacitors : I• Low voltage -> series connection
© Mats Alaküla EHS
2
21
CC uCW
units unit
system
C
C
#
11
http://www.maxwell.com/products/ultracapacitors/industries/transportation
30 ton, 50 km/h = ½*m*v^2 = 0.82 kWh0.82/0.0023 = 355 kg
Supe Capacitors : II
© Mats Alaküla EHS
Fly wheel energy storage• High speed rotating mass
© Mats Alaküla EHS
2
21
wheelJW mech
• A flywheel made of steel and carbon fibre that rotated at over 60,000 RPM inside an evacuated chamber
• The flywheel casing featured containment to avoid the escape of any debris in the unlikely event of a flywheel failure
• The flywheel was connected to the transmission of the car on the output side of the gearbox via several fixed ratios, a clutch and a Continuously Variable Transmission
• 60 kW power transmission in either storage or recovery
• 400 kJ of usable storage• A total system weight of 25 kg
A l k i l f 13 li