2. Module-1:Introduction to Hybrid Electric Vehicles and
Conventional Vehicles
Introduction to Hybrid Electric Vehicles: History of
hybrid and electric vehicles, social and environmental
importance of hybrid and electric vehicles, impact of
modern drive-trains on energy supplies;
Conventional Vehicles: Basics of vehicle performance,
vehicle power source characterization, transmission
Characteristics, mathematical models to describe
vehicle performance.
3. What is an HEV?
HEV – Hybrid Electric Vehicle
A vehicle that has two or more energy conversion
technologies combined with one or more energy
storage units
4. Possible combinations include diesel/electric,
gasoline/fly wheel, and fuel cell (FC)/battery
Typically, one energy source is storage, and the
other is conversion of a fuel to energy.
The combination of two power sources may
support two separate propulsion systems.
Thus to be a True hybrid, the vehicle must have
at least two modes of propulsion.
5.
6. For example, a truck that uses a diesel to drive a
generator, which in turn drives several electrical
motors for all-wheel drive, is not a hybrid.
But if the truck has electrical energy storage to
provide a second mode, which is electrical assists,
then it is a hybrid Vehicle.
7. History of hybrid and electric
vehicles
The story begins in Scotland in 1839, where Robert
Anderson claims to have built the World’s first
electric vehicle in his workshop in Aberdeen.
Technology at the time severely limited both range
and speed of any electric model, a problem Sir David
Salomon encountered in 1870 with the development
of his electric protoype – which used a light electric
motor but very heavy storage batteries. Driving
speed and range were therefore poor.
8. The first hybrid car was built in the year 1899 by engineer Ferdinand
Porsche. Called the System Lohner-Porsche Mixte, it used a
gasoline engine to supply power to an electric motor that drove the
car's front wheels. The Mixte was well-received, and over 300 were
produced.
In 1904, Henry Ford developed his range of low-price, light weight
petrol-powered cars, later to include the Model T, significantly
enough that within a few years the Electric Vehicle Company went
bust.
Electric and hybrid vehicles continued to develop, however, and in
1916 two electric vehicle makers – Baker of Cleveland and Woods
of Chicago – both bought hybrid cars to market. Woods claimed that
its hybrid model reached a top speed of 35mph and achieved fuel
efficiency of 48mpg (miles per gallon). However, it was more
expensive and less powerful than its petrol-powered competition,
and therefore sold poorly – just six hundred were made.
9. The mass market for petrol vehicles exploded in the US in the
1920’s and 30’s as local and federal governments developed
roads across the country. By 1935 the electric vehicle had all
but disappeared.
Fast forward to the 1960’s, though, and the electric and
hybrid vehicle was set to return in a big way. In 1966 U.S.
Congress introduced its first bills recommending the use of
electric vehicles in order to reduce air pollution – which had
steadily become a significant problem in many major cities.
Two years later, in 1968, three scientists working at
components supplier TRW created a practical hybrid
powertrain. Designated as an electromechanical system
(EMT), its aim was to provide swift vehicle performance with
an engine smaller than required by a conventional internal
combustion unit. Many of the engineering concepts
incorporated in that system are used in today’s hybrids.
10. 1973 saw the introduction of the Arab oil embargo, and with it the
price of fuel rocketed. Volkswagen’s ‘Taxi’, a hybrid which allowed
switching between the petrol engine and electric motor, logged
over 8,000 miles on the road and was shown at car shows
throughout the world.
Over the next 25 years, auto manufacturers spent billions of
dollars on research and development of hybrid technologies.
In spite of this, very few vehicles were produced that could
both reduce the world's dependence on oil and compete with
gasoline vehicles on price and performance.
In the late 1990s, a handful of all-electric vehicles were
introduced, the GM EV1 and Toyota RAV-4 EV being two
examples. These all-electric vehicles failed to attract
widespread interest and were soon dropped from production.
It wasn't until Toyota released the Prius in Japan in 1997 that
a viable alternative to gas-powered vehicles was introduced.
11. In 1999, the Honda Insight became the first mass-production
HEV released in the United States. The two-door, two-seat
Insight may have been first, but it was the Toyota Prius sedan,
released in the United States in 2000, that gave hybrid
technology the foothold it was looking for. In the years since its
United States introduction, the Prius has become synonymous
with the term "hybrid." It is the most popular HEV ever
produced, and auto manufacturers around the world have
used its technology as a basis for countless other vehicles.
In this era of ever-increasing environmental awareness, the
Prius may be in for some stiff competition. Honda released the
second-generation Insight, and Chevrolet introduced of
the Volt. As hybrid technology continues to improve, it will
continue developing an even stronger foothold in the world's
auto market. Whatever the future holds, one thing is certain,
auto manufacturers will keep developing and building hybrids,
just as they have all along.
12. The next change that consumers should expect to see
in the next few years is automakers producing plug-in
versions of hybrid vehicles that are able to operate at
an extended range in all-electric mode. While
consumers have modified current versions of hybrid
vehicles to be plug-in models, there are currently no
commercially available hybrid cars in a plug-in
configuration. Expect the first generation of plug-in
hybrids to have a 40 to a 70-mile range in electric-only
mode at speeds of up to 50 mph.
28. HEV Objectives
Objectives the HEV wants to obtain:
Maximize fuel economy
Minimize fuel emissions
Minimize propulsion system cost to keep
affordable
Maintain acceptable performance with a
reasonable cost
Reduce the conventional car weight
29. HEV Advantages Over Conventional
Engines
Regenerative Braking
Reduction in engine and vehicle weight
Fuel efficiency is increased
Emissions are decreased
Cut emissions of global warming pollutants by 1/3 or
1/2
Reduce the dependency on fossil fuels
Some states offer incentives with owning an HEV
~2 times more efficient than conventional engines
30. Motor Components
Drive train
Electric Motors/Controllers
Electric Energy Storage systems
Hybrid power units
Transmission
31. Motor Components
Basic Components
An Armature or Rotor
A Commutator
Brushes
An Axle
Field Magnet
DC Power Supply
Electric Motors/Controllers
32. Motor Components
Electric Motor/Controllers
Advanced electronics allows the motor to act as a generator
Draws energy to accelerate and regenerates the battery when
slowing down
Motor uses magnets and magnetism to create motion
33. Motor Components
Electric Energy Storage Systems
Batteries: Lithium Ion and Nickel-metal hydride batteries
Ultracapacitors
Flywheels
34. Motor Components
Electric Energy Storage Systems
Desirable attributes:
High-peak and pulse specific power
High specific energy at pulse power
High charge to maximize regenerative braking
Long life
Challenges:
Accurate techniques to determine battery state of
charge
Develop abuse-tolerant batteries
Recycleability
35. Motor Components
Batteries Nickel-Metal Hydride Lithium Ion
Current Uses Computer and Medical equipment Laptops and Cell phones
Life Cycle Much larger than lead acid batteries Low
Current
contribution
Used successfully in low production
of HEVs
Challenges High Cost
High self-discharge
Heat generation
Control losses of hydrogen
Low cell efficiency
Life cycle
Cell and battery safety
Abuse tolerant
Acceptable cost
Miscellaneous Reasonable specific energy and
power
Components are recyclable
Abuse-tolerant
High specific energy and power
High energy efficiency
Good high-temperature
performance
Low elf-discharge
Recyclable parts
NA
36. Motor Components
Energy Storage: Ultracapacitors
Store energy as an electric charge in a polarized liquid layer
between an ionically electrolyte and conducting electrode
Primarily used for acceleration, climbing hills and regenerative
braking
37. Motor Components
Energy Storage: Flywheel
Store kinetic energy within a rapidly
spinning wheel
Complex, heavy, and large
Contains no acid or hazardous material
Not affected by temperature
Delivers a smooth flow of power
Click for more information on the fly wheel
38. Motor Components
Charging/Discharging the Battery
The following are some links to visually display the characteristics
of the motor and engine during different scenarios
Driving at low speeds
City driving
Highway driving
Uphill driving
Coasting/Slowing/Stopping
39. Motor Components
Regenerative Braking
When the driver brakes, the motor becomes
a generator and the kinetic energy
generates electricity stored into the
battery
The Toyota Prius uses about 30% of the heat
lost kinetic energy from braking
40. Motor Components
Compression Ignition Direct Injection Engines (CIDI)
Spark Ignition Engines
Gas Turbines
Fuel Cells
Hybrid Power Units
4 Types:
41. Motor Components
Hybrid Power Units: CIDI
Most promising power unit
Achieves combustion through compressions
without the use of a spark plug
High pressure injection of the fuel into the
combustion chamber
Throttle and heat losses travels into the
combustion chamber increasing thermal
efficiency
42. Motor Components
Hybrid Power Units: Spark Ignition
Runs on an Otto cycle
Uses a homogeneous air-fuel mixture
before entering the combustion
chamber
When the combustion chamber is
compressed, the spark plug is ignited
Controlled by limiting the amount of
air allowed into the engine
43. Motor Components
Hybrid Power Units: Gas Turbines
Runs on a Brayton cycle
A compressor raises the pressure and temperature of the inlet air
Air is moved to the burner and fuel is injected and combusted to
raise the air temperature
Power is produced when
the heated pressure
mixture is expanded and
cooled through the
turbine
44. Motor Components
Hybrid Power Units: Fuel Cells
Generate electricity through an
electrochemical reaction
combining hydrogen with
ambient air
Pure hydrogen or any fossil fuel
produced is used as hydrogen-
rich gas
Water vapor is emitted
Click to see an animation of the
steps to make electricity from a
fuel cell.
45. Motor Components
Continuous Variable Transmission (CVT)
Automated shifted transmission
Manual transmission
Traditional automatic transmission with torque converter
Transmission
4 Types:
46. Motor Components
Transmission: CVT
Infinite number of variable transmissions
Currently not able to compete with 4-speed
and 5-speed transmissions in size, cost,
and reliability
Provides seamless, stepless acceleration
and deceleration
The Toyota Prius uses this
47. Vehicle Propulsion
Series “Power Assist”
Parallel “Range Extender”
Dual-Mode: Combination of a series and
parallel
48. Vehicle Propulsion
Series Configuration
Small fuel-burning engine that directly drives an alternator to
generate electricity
Electricity is stored in the battery or sent the to electric motor
When the batteries are drained to a certain level, the engine
turns on and recharges the battery
49. Vehicle Propulsion
Parallel Configuration
Two power paths
Hybrid power unit or electric propulsion system or both can
power the wheels
For long trips the engine is used
For hills, acceleration, and high power scenarios the electric
motor is used
50. Vehicle Propulsion
Propulsion
Comparison
Series Configuration Parallel Configuration
Benefits Engine never idles reducing
emissions
Engine drives a generator to run
at optimal performance
Allows a variety of options in
mounting the engine
Some don’t need a transmission
Has more power from
simultaneous power from motor
and engine
Don’t need a separate
generator because the motor
generates the battery
Power is directly coupled to the
road so can be more efficient
52. Examples
Toyota Prius Honda Insight
Electric
Motor/Generator
/Power Storage
Output 273.6V (228 cells @
1.2V)
144V (120 cells @
1.2V)
Battery Type Nickel-Metal Hydride Nickel Metal Hydride
Power Output 33kW @ 5600rpm 10kW @ 3000rpm
Transmission ECVT CVT
Mileage
City/Highway
52/45 61/68
Gasoline Engine Horsepower @
rpm
70hp @ 4500rpm 67h @ 5700rpm
Emission
Rating
SULEV ULEV
53. HEV Challenges
Energy storage devices with high power-to-energy
ratios
Frequent shut down and start up of the HEV
Reduce the size, weight, and cost
Higher efficiency in the conversion of fuel to useful
power
Advanced configurations for the propulsion system
components
54. Review
What is an HEV?
HEV objectives
HEV advantages over conventional
engines
Motor components
Vehicle propulsion
Examples
HEV Challenges
