HybridElectricCarsRevG.ppt Barry K. James June 2015
CANNOCK CHASE U3A
SCIENCE & TECHNOLOGY GROUP
Hybrid, Electric and Fuel Cell Cars:
How they work
July 2015
VEHICLE TYPES (AVAILABLE TODAY)

Conventional petrol, diesel or LPG (IC) engine
One fossil fuel energy source, toxic emissions (except LPG)
 Performance maintained throughout tank of fuel
 Approx 300+ miles per tank of fuel

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Pure electric (EV)


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Rechargeable battery is the only energy source
Approx 60 – 100 miles per battery charge
Long battery charge can take around 8 hours+
Braking will generate power to charge the battery
Batteries will probably need replacing during life
Hybrid, petrol/electric (HEV)





e.g
Zoe
Leaf
GM Volt
Smart
Tesla
Combination of fossil fuel and battery power
Types include “Plug-in” and non plug-in
Can usually use in pure electric, IC engine, or both electric and IC together modes
e.g.
Usually a short range in electric only mode
Prius
Braking will generate power to charge the battery
Auris
Lexus
WHAT’S IN A PURE ELECTRIC CAR (EV)?
Smart 55kW, 120 Nm, 12,000 rpm, 250-400 Vdc
Drivetrain (EV engine)
Motor
3 phase
brushless
HV Battery Pack with cell management,
control and cooling.
Neodimium magnets.
Single Li-ion Cell
3.7V nominal
Power modules &
control
DC to DC
converter
For 12V system
Inverter
power
control
PURE EV POWER & CONTROL CIRCUIT
•
•
•
WHAT’S IN THE HV LITHIUM ION BATTERY
Can be 100+ cells
PACK
Safety circuit breakers
Every cell is monitored for
temperature and voltage
constantly.
The battery temp and charge
state can affect car
performance.
•
•
•
•
Voltage charged: 400V+ dc
Voltage discharged: 240V
For a 400HP motor:
Current = 1200A !
•
Huge weight and cost!
Other older battery types include:
Cooling
Nickel Metal Hydride (NiMH)
Nickel Cadmium (NiCd)
Power monitoring sensor
WHAT DRAINS THE HV BATTERY?

Main traction motor(s)
Heater (EVs are 90% + efficient, petrol 30%, diesel 50%)
Air conditioning
Power steering, heated screens
Lighting, instrumentation, wipers
Brake vacuum pump
Cooling pumps for Inverter, Motor & HV battery
ABS, traction and stability control
Power and battery controllers, engine management
400VDC to 12VDC converter for above
(Charger on board)

…..So the battery won’t last long if the weather is hot or cold
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BEWARE: LITHIUM ION BATTERIES
Lithium Ion batteries getting overheated – creates thermal runaway
Never short out lithium batteries or let them get overheated in use.
Also used in laptops and phones!
COMPARISON OF ENERGY STORAGE
METHODS




Petrol
Energy
Cost
Life
12000 Wh/kg
$30 / kW
5000 hours
Lithium Ion Battery Pack
Energy
Cost
Life
120 Wh/kg
$1000 / kW
500 cycles (2500hours)
UltraCapacitors (Lots of instant power, Fast charge)
Energy
Cost
Life
5 Wh/kg (low)
High
Limitless cycles
Conclusion
 Petrol
has 100 times the energy of a battery (range).
 Batteries only cost a few pence per mile to run.
THE INVERTER POWER CONTROL
Typical power switching
module x 3. 1400A capability
IGBT module
Processing control
To car
controls
Power cables to this
module can be 20mm
diameter (75mm2)
To motor (3)
To HV Battery (2)
Current sensor,
monitoring and
control (4 off)
Toyota Prius
Power controller
IGBT
3 Phase power to motor
CHARGING A PURE EV
Type 1: Slow 3kW
Home ac
charge
point
Street
charge
point
Type 2: Fast 7kW+
DRIVING A PURE EV
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Very quiet, maximum acceleration from rest. One gear for whole
speed range: easy to drive. Low cost/mile.
Power may reduce when battery is low. Low and high battery temp
causes power reduction. Battery needs cooling.
Good for city centre reduction in CO2; “Zero” emission.
Short trips only due to low range, so probably a second car.
High acceleration and high speeds use a lot of energy.
Use of ancilliaries (AirCon, heater) will deplete the battery.
Braking will recharge the battery (slightly). Called “regenerative
braking”. Trailing throttle will also generate.
Charging battery……a long process for another 60 + miles.
High voltage lithium battery pack is used. Limited life.
Inverter:
280kW
14kW loss
24kg
EXCITING AUDI R8 E-TRON
REAL PERFORMANCE – NOT A MILK FLOAT!
Battery 500kg
Motors:
12,200rpm
820Nm
R8 e-tron
0-62mph 4.6s
155mph
465bhp
HYBRID CARS
Ampera
Prius
BMW i3
Volvo
Yaris
Lexus
WHAT’S IN A HYBRID CAR

2 electric motors and power controllers coupled to an IC
engine, a power splitter, and HV battery.
Power control
Battery, motors and power
controllers will be smaller than a
pure EV.
Toyota Prius Drivetrain
2 Types of Hybrid:
• Plug-in (PHEV)
• Non- plug-in (HEV)
HYBRID ENERGY DISPLAY
Electric only drive (depletes battery)
Braking (Regen) charges battery
IC engine drive only uses petrol
IC engine AND electric doubles torque
DRIVING A HYBRID CAR
 Starting
from standstill:
 Usually
electric only until ~5mph which depletes the
battery, then IC engine starts.
 The generator will start the IC engine when required to
avoid battery depletion.
 Heavy acceleration should start IC engine and use motor
simultaneously for increased torque and power (parallel
mode).
DRIVING A HYBRID CAR
 Normal
 Under
running:
normal driving, the IC engine will power the car.
Heavy throttle pedal can “parallel” motors and engine.
 IC engine will recharge battery via the generator, but uses
fuel to do it in a HEV. PHEV can be charged from mains.
 Foot off throttle (trailing throttle) or braking will regenerate
electricity to charge battery.
 Regenerative braking will feel like engine braking.
 Mechanical brakes can have less wear with regenerative
braking.
HYBRID CAR CONCLUSIONS
 Pros
and Cons
 Hybrid
has no advantage on motorway if no braking occurs
(same as IC but carrying more weight).
 Maximum acceleration from rest using motors.
 Emissions not much different from standard IC car.
 Fuel economy not much different from standard IC car.
 Heavy battery, motors and power controllers.
 Non-plug-in hybrids have to use fuel to charge the battery.
 Engine acts as a range extender for the battery, so no need to
charge. Same range as petrol car.
 Cost of car is high compared to standard petrol.
 Allowable for congestion charge cities.
WHY DO WE NEED TO RECOVER
ENERGY FROM BRAKING?

Fuel efficiency in hybrid cars. Braking will recover a
small amount of energy to charge battery.

Small battery charging opportunities for pure electric
cars when braking.
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Energy collection for use in hybrid race cars Braking
collects energy – Driver selects when to use the energy
for acceleration. (KERS in F1 collected energy for a 6
second burst of 60hp).
Race Car Hybrid (KERS) System
(Japanese race series)
RACE CAR
NEXT
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TEA ANYONE?

THE FUTURE OF ELECTRIC AND RANGE
EXTENDERS….The Fuel Cell.
CONCLUSIONS ON HYBRID & ELECTRIC
CARS
Battery energy does not last long for pure EVs
 Long battery recharge time for pure EVs
 Batteries may need replacing over life of car
 Pure EVs can be expensive to buy
 Pure EVs are cheaper to run than petrol or diesel
 “Zero emission” not really true – just shifted elsewhere

Hybrids not much advantage on motorways
 Hybrids expensive with extra equipment
 Hybrids give little or no improvement in running costs over a
standard diesel


So, what about a “Alternative fuel to extend range”?
FUEL CELL CARS –
THE ULTIMATE COMBINATION?
H2 + 1/2O2 = H2O + Elec
Hydrogen dispensing
Proton Exchnage
Membrane (PEM)
Maybe 20202030!
TYPES OF FUEL CELL

Alkaline
 Electrolyte

Phosphoric Acid
 Acid

KOH, Used in the Apollo spacecraft.
electrolyte, 40% efficient, buses in CA.
Proton Exchange Membrane (PEM)
 Permeable
plastic electrolyte like cling film, platinum, 200F, most
likely for cars.
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Solid Oxide
 Calcium,
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zirconium or sodium electrolyte, 1800F, domestic
Molton Carbonate
 Potassium

or lithium carbonate electrolyte, 1200F, utilities
Reformers: Can convert methanol but not zero emission
CONCLUSIONS ON FUEL CELLS

Cost
 Very

Complication
 Very

high presently
complicated control required
Fuel
 Requires
hydrogen infrastructure for zero emission
 Requires reformer for methanol (not zero emission)

Timeframe
 Probably

2025 onwards to get cost down
But seems ideal combination
ACKNOWLEDGEMENTS

ANY QUESTIONS?
Some internal photos and 3D views courtesy of Zytek
Electric Vehicles, Lichfield, UK, Daimler Mercedes
Smart Vehicles and VAG Audi.
 Other pictures courtesy of the Internet.
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TOPICS CALENDAR
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November:
Using an Internet Browser and security for banking online.
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December:
No meeting
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January:
A Famous Scientist study. Leonardo DaVinci.
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February:
facts.
Energy. The practical truth about solar PV panels and power

March:
Practical Session 1. Soldering, Components, Kits
construction; crystal radio, clock, solar car

April:

May:
Cancelled
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June:
Using Microsoft PowerPoint
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July:

Aug:
A Famous Scientist 2: Guglielmo Marconi and radio.

Sept:
Introduction to 3D Graphics (movies)
Practical Session 2. Soldering, Components, Kits
construction; crystal radio, clock, solar car
The Electric & Hybrid Car. The workings inside the engine
and battery of pure electric and hybrid cars.
FUTURE SESSION IDEAS
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The use and benefit of technology (PC’s,
Cameras/Photography, Tablets, Music MP3, etc)
Scientific and Engineering achievements of interest.
Famous Scientists or Engineers (Brunel, Marconi, Faraday)
DVDs of Railways, Industrial Age, Air transport, Road
transport, Buildings (Eiffel, Bridges), Waterways.
Own interests, diagrams, photos.
Group visits

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(JCB, Jaguar, Jodrell Bank, BBC, Transport museum,
Chasewater engine sheds, Space Centre, RAF Cosford?)
Electronics practical projects and workshops

(Soldering, Components, Raspberry Pie, Picaxe)
PICAXE PROJECTS
Anyone look at the Picaxe or Revolution Education
websites?
 Any project ideas?

How about 2 robot teams competing for the best obstacle
course program?
 How about making a weather station or kit?
 Any more suggestions?
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