Hybrid Electric Vehicle
Hybrid Electric Vehicle
Hybrid Electric Vehicle
Seminar Report
ABSTRACT
In an era where energy conservation has become the latest topic of discussion not
only among the erudite but also among the ordinary responsible denizens, fuel efficiency
along with minimum pollution has become the benchmark for any new automobile.
And in the same context Hybrid Electric Vehicle come as the latest addition. By the
name itself it can be inferred that a Hybrid Electric Vehicle is an improvisation to the
traditional gasoline engine run car combined with the power of an electric motor.
The seminar on the above topic intends to bring to notice the concepts associated
with the hybrid technology through the following topics components and constituents,
need, efficiency, performance, etc.
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CONTENTS
CHAPTERS
INTRODUCTION
WHAT IS A HYBRID VEHICLE?
HYBRID STRUCTURE
HYBRID COMPONENT.
INTERNAL COMBUSTION ENGINE.
ELECTRIC MOTOR
ALTERNATOR
EVOLUTION OF HYBRID
HYBRID PERFORMANCE
HYBRID EFFICIENCY
WHATS AVILABLE NOW?
HYBRID MILEAGE TIPS
CONCLUSION
REFERENCES
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INTRODUCTION
Have you pulled your car up to the gas pump lately and been shocked by the high
price of gasoline? As the pump clicked past $20 or $30, maybe you thought about trading
in that SUV for something that gets better mileage. Or maybe you are worried that your
car is contributing to the greenhouse effect. Or maybe you just want to have the coolest
car on the block.
Currently, there is a solution for all this problems; its the hybrid electric
vehicle. The vehicle is lighter and roomier than a purely electric vehicle, because there is
less need to carry as many heavy batteries. The internal combustion engine in hybridelectric is much smaller and lighter and more efficient than the engine in a conventional
vehicle. In fact, most automobile manufacturers have announced plans to manufacture
their own hybrid versions.
How does a hybrid car work? What goes on under the hood to give you 20 or 30
more miles per gallon than the standard automobile? And does it pollute less just because
it gets better gas mileage. In this seminar we will study how this amazing technology
works and also discuss about TOYOTA & HONDA hybrid cars.
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Any vehicle is hybrid when it combines two or more sources of power. In fact, many
people have probably owned a hybrid vehicle at some point. For example, a mo-ped (a
motorized pedal bike) is a type of hybrid because it combines the power of a gasoline
engine with the pedal power of its rider.
Hybrid electric vehicles are all around us. Most of the locomotives we see pulling
trains are diesel-electric hybrids. Cities like Seattle have diesel-electric buses -- these
can draw electric power from overhead wires or run on diesel when they are away from
the wires. Giant mining trucks are often diesel-electric hybrids. Submarines are also
hybrid vehicles -- some are nuclear-electric and some are diesel-electric. Any vehicle
that combines two or more sources of power that can directly or indirectly provide
propulsion power is a hybrid.
The most commonly used hybrid is gasoline-electric hybrid car which is just a
cross between a gasoline-powered car and an electric car. A gasoline-electric hybrid car
or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an
internal combustion engine which drives a generator to provide the electricity and may
also drive a wheel. In hybrid electric vehicle the engine is the final source of the energy
used to power the car. All electric cars use batteries charged by an external source, leading
to the problem of range which is being solved in hybrid electric vehicle.
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HYBRID STRUCTURE
You can combine the two power sources found in a hybrid car in different ways.
One way, known as a parallel hybrid, has a fuel tank, which supplies gasoline to the
engine. But it also has a set of batteries that supplies power to an electric motor. Both the
engine and the electric motor can turn the transmission at the same time, and the
transmission then turns the wheels.
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transmission independently. As a result, in a parallel hybrid, both the electric motor and
the gas engine can provide propulsion power.
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Figure 2. Series hybrid car
Another way of combining the power sources found in a hybrid car is by series
hybrid. In a series hybrid (Figure 2 above) the gasoline engine turns a generator, and the
generator can either charge the batteries or power an electric motor that drives the
transmission. Thus, the gasoline engine never directly powers the vehicle. Take a look at
the diagram of the series hybrid, starting with the fuel tank, and you'll see that all of the
components form a line that eventually connects with the transmission.
HYBRID COMPONENTS
Gasoline engine - The hybrid car has a gasoline engine much like the one you will
find on most cars. However, the engine on a hybrid will be smaller and lighter, and is
more efficient than the engine in a conventional vehicle, because the engine runs at a
relatively constant speed, and does not need to provide direct power for acceleration,
which is the biggest reason for large engines. Use advanced technologies to reduce
emissions.
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Fuel tank - The fuel tank in a hybrid is the energy storage device for the gasoline
engine. Gasoline has a much higher energy density than batteries do. For example, it takes
about 1,000 pounds of batteries to store as much energy as 1 gallon (7 pounds) of
gasoline.
Electric motor - The electric motor on a hybrid car is very sophisticated. Electric
motor used in hybrid cars are usually dc series motor since its versatile and ease with
which a variety of speed-torque characteristics can be obtained, and wide range of speed
control is also possible in this. Advanced electronics allow it to act as a motor as well as a
generator. For example, when it needs to, it can draw energy from the batteries to
accelerate the car. But acting as a generator, it can slow the car down and return energy to
the batteries.
Generator - The generator is similar to an electric motor, but it acts only to produce
electrical power. It is used mostly on series hybrids. Generator used in hybrid electric
vehicle is alternator since cooling is easy and hence maximum output and also the
output/weight ratio is higher than that of the DC generator.
Power split device The power split device is a clever gearbox that hooks the
internal combustion engine and D.C.motor together. The power split device helps the
vehicle to accelerate to a speed of about 15km/hr before switching on the gasoline engine.
The engine starts only after the vehicle attains a certain speed. Once the engine starts it
operates on a narrow speed band. The power split device allows the engine to stay in its
most efficient load and speed range most of the time.
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Batteries - The batteries in a hybrid car are the energy storage device for the electric
motor. Unlike the gasoline in the fuel tank, which can only power the gasoline engine, the
electric motor on a hybrid car can put energy into the batteries as well as draw energy
from them. The batteries used in HEV is Ni-Cd cells since its lighter than the lead acid
cells and its also mechanically strong and can stand very rough use.
Transmission - The transmission on a hybrid car performs the same basic function
as the transmission on a conventional car. Some hybrids, like the Honda Insight, have
conventional transmissions. Others, like the Toyota Prius, have radically different ones,
which well talk about later.
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Figure 3
mowers, but most cars have more than one cylinder (four, six and eight cylinders are
common). In a multi-cylinder engine the cylinders usually are arranged in one of three
ways: inline, V or flat.
manufacturing-cost and shape characteristics that make them more suitable in some
vehicles.
Sparkplug
The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can
occur. The spark must happen at just the right moment for things to work properly.
Valves
The intake and exhaust valves open at the proper time to let in air and fuel and to let out
exhaust. Note that both valves are closed during compression and combustion so that the
combustion chamber is sealed.
Piston
A piston is a cylindrical piece of metal that moves up and down inside the cylinder.
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Pistonrings
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge
of the cylinder. The rings serve two purposes:
They prevent the fuel/air mixture and exhaust in the combustion chamber from
leaking into the sump during compression and combustion.
They keep oil in the sump from leaking into the combustion area, where it would be
burned and lost.
Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it
because the engine is old and the rings no longer seal things properly.
Combustionchamber
The combustion chamber is the area where compression and combustion take place. As
the piston moves up and down, you can see that the size of the combustion chamber
changes. It has some maximum volume as well as a minimum volume. The difference
between the maximum and minimum is called the displacement and is measured in liters
or CCs (Cubic Centimeters, where 1,000 cubic centimeters equals a liter). So if you have
a 4-cylinder engine and each cylinder displaces half a liter, then the entire engine is a "2.0
liter engine." If each cylinder displaces half a liter and there are six cylinders arranged in a
V configuration, you have a "3.0 liter V-6." s. A cylinder that displaces half a liter can
hold twice as much fuel/air mixture as a cylinder that displaces a quarter of a liter, and
therefore you would expect about twice as much power from the larger cylinder (if
everything else is equal). So a 2.0 liter engine is roughly half as powerful as a 4.0 liter
engine. You can get more displacement either by increasing the number of cylinders or by
making the combustion chambers of all the cylinders bigger (or both).
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Connectingrod
Connecting rod connects the piston to the crankshaft. It can rotate at both ends so that
angle can change as the piston moves and the crankshaft rotates.
Crankshaft
The crank shaft turns the pistons up and down motion into circular motion just like a
crank on a jack-in-the-box does.
Sump
The sump surrounds the crankshaft. It contains some amount of oil, which collects in the
bottom of the sump (the oil pan).
The big engine is heavier than the small engine, so the car uses extra energy every
time it accelerates or drives up a hill.
The pistons and other internal components are heavier, requiring more energy each
time they go up and down in the cylinder.
Bigger engines usually have more cylinders, and each cylinder uses fuel every time
the engine fires, even if the car isn't moving.
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This explains why two of the same model cars with different engines can get
different mileage. If both cars are driving along the freeway at the same speed, the one
with the smaller engine uses less energy. Both engines have to output the same amount of
power to drive the car, but the small engine uses less power to drive itself
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ELECTRIC MOTOR
An electric motor is all about magnets and magnetism: A motor uses
magnets to create motion. We know the fundamental law of all magnets: Opposites attract
and likes repel. So if you have two bar magnets with their ends marked "north" and
"south," then the north end of one magnet will attract the south end of the other. On the
other hand, the north end of one magnet will repel the north end of the other (and
similarly, south will repel south). Inside an electric motor, these attracting and repelling
forces create rotational motion.
DC series motor used in hybrid electric vehicle is a versatile and flexible
machine. It can satisfy the demands of load recurring high starting, accelerating and
retarding torques. A DC machine is also easily adaptable for drives with a wide range of
speed control and fast reversals. In the diagram shown below we can see two magnets in
the motor: The armature (or rotor) is an electromagnet, while the field magnet is a
permanent magnet (the field magnet could be an electromagnet as well, but in most small
motors it isn't in order to save power). Different parts used in a simple DC motor are as
shown in the diagram below:
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Part
of
an
electric motor
Armature or rotor
Stator
Commutator
Brushes
Field magnet
The magnetic circuit of a DC consists of the armature magnetic material
(core), the air-gap, field poles and yoke. The yoke of a DC machine is a annular ring to
the middle of which is bolted field poles and the interlopes. The interlopes or
commutation poles are narrow poles fixed to the yoke, midway between the main field
poles. The use of an electric field winding, which supplies electric energy to establish a
magnetic field in the magnetic circuit , result in the great diversity and a variety of
performance characteristics. The armature winding is connected to the external power
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ALTERNATOR
An electric generator is a device that converts mechanical energy into electrical energy .it
produce alternating currents. It works on the principle of electromagnetic induction which
states that when a coil is rotated about an axis perpendicular to the direction of uniform
magnetic field, an induced emf is produced across it. Alternator
requires a magnetic
field as well as a rotating coil. The coil is wound in a special manner know as armature.
To produce current either this armature or magnetic field can be rotated. The only thing is
that it should cut the magnetic field. Usually the armature winding is stationary (called
stator) and the field winding is rotating (know as rotor). An alternator consist of
Frame or housing
Stator
Rotor
Frame or housing: Frame is an important part of alternator. This encloses the entire
alternator assembly and is made of aluminum. Frame is made up of two parts. The front
part of the frame has ball bearing, and the rear part contains roller bearing for supporting
the rotor. The front part usually known as drive end housing and rear part is known as
brush end housing.
Stator: The armature is an iron ring framed of laminated special magnetic iron or steel
alloy having slots on its inner periphery to accommodate armature conductors and is
known as stator. Stator is the stationary part of the alternator. Field rotates between the
stator so that the fluxing of the rotating field cuts the core of the stator, which includes the
required emf.
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Rotor: It consists of an iron core around the rotor shaft. Many turns of the copper wire
coated with varnish are wound around the core. On both sides of the rotor winding are the
thick metal plates bent over the winding with triangular fingers called poles. These metal
plates are called pole pieces. The pole pieces are placed interfacing each other so that
when the current flows through the winding, these poles pieces acquire opposite polarity.
This will result in alternating north and south magnetic poles on the pole fingers. This
creates magnetic fields between the alternating pole fingers.
Slip rings and brushes: Due to the cutting of the magnetic field, an emf and hence a
current is produced in the rotor winding. Since the coil is rotating, its not possible to take
current from the coil using wires. But special arrangements are necessary for carrying
current to outside. The current from the rotor winding is usually carried through the
copper slip rings and the carbon brushes. As these brushes carry only the field current
(2.5A), it has longer life.
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pollution and generally gets poor gas mileage. An electric car, on the other hand, produces
almost no pollution, but it can only go 50 to 100 miles (80 to 161 km) between charges.
And the problem has been that it is very slow and inconvenient to recharge.
A driver's desire for quick acceleration causes our cars to be much less efficient than they
could be. You may have noticed that a car with a less powerful engine gets better gas
mileage than an identical car with a more powerful engine. Just look at the window
stickers on new cars at a dealership for a city and highway mpg comparison.
The amazing thing is that most of what we require a car to do uses only a small
percentage of its horsepower! When you are driving along the freeway at 60 mph (96.6
kph), your car engine has to provide the power to do three things:
Overcome the aerodynamic drag caused by pushing the car through the air
Overcome all of the friction in the car's components such as the tires, transmission,
axles and brakes
Provide power for accessories like air conditioning, power steering and headlights
For most cars, doing all this requires less than 20 horsepower! So, why do you need a car
with 200 horsepower? So you can "floor it," which is the only time you use all that power.
The rest of the time, you use considerably less power than you have available.
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HYBRID PERFORMANCE
The key to a hybrid car is that the gasoline engine can be much smaller than the one in a
conventional car and therefore more efficient. But how can this smaller engine provide the
power your car needs to keep up with the more powerful cars on the road?
Let's compare a car like the Chevy Camaro, with its big V-8 engine, to our hybrid car with
its small gas engine and electric motor. The engine in the Camaro has more than enough
power to handle any driving situation. The engine in the hybrid car is powerful enough to
move the car along on the freeway, but when it needs to get the car moving in a hurry, or
go up a steep hill, it needs help. That "help" comes from the electric motor and battery -this system steps in to provide the necessary extra power.
The gas engine on a conventional car is sized for the peak power requirement (those few
times when you floor the accelerator pedal). In fact, most drivers use the peak power of
their engines less than one percent of the time. The hybrid car uses a much smaller engine,
one that is sized closer to the average power requirement than to the peak power.
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HYBRID EFFICIENCY
Besides a smaller, more efficient engine, today's hybrids use many other
tricks to increase fuel efficiency. Some of those tricks will help any type of car get better
mileage, and some only apply to a hybrid. To squeeze every last mile out of a gallon of
gasoline, a hybrid car can:
Recover energy and store it in the battery - Whenever you step on the brake pedal
in your car, you are removing energy from the car. The faster a car is going, the more
kinetic energy it has. The brakes of a car remove this energy and dissipate it in the form
of heat. A hybrid car can capture some of this energy and store it in the battery to use later.
It does this by using "regenerative braking." That is, instead of just using the brakes to
stop the car, the electric motor that drives the hybrid can also slow the car. In this mode,
the electric motor acts as a generator and charges the batteries while the car is slowing
down.
Sometimes shut off the engine - A hybrid car does not need to rely on the gasoline
engine all of the time because it has an alternate power source -- the electric motor and
batteries. So the hybrid car can sometimes turn off the gasoline engine, for example when
the vehicle is stopped at a red light.
Use low-rolling resistance tires - The tires on most cars are optimized to give a
smooth ride, minimize noise, and provide good traction in a variety of weather conditions.
But they are rarely optimized for efficiency. In fact, the tires cause a surprising amount of
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drag while you are driving. Hybrid cars use special tires that are both stiffer and inflated
to a higher pressure than conventional tires. The result
is that they cause about half the drag of regular tires.
your engine does goes into pushing the car through the
car
air. This force is known as aerodynamic drag. This drag force can be reduced in a variety
of ways. One sure way is to reduce the frontal area of the car (Figure 5). Think of how a
big SUV has to push a much greater area through the air than a tiny sports car.
Reducing disturbances around objects that stick out from the car or eliminating them
altogether can also help to improve the aerodynamics. For example, covers over the wheel
housings smooth the airflow and reduce drag. And sometimes, mirrors are replaced with
small cameras. This site provides more information on car aerodynamics.
Use lightweight materials - Reducing the overall weight of a car is one easy way to
increase the mileage. A lighter vehicle uses less energy each time you accelerate or drive
up a hill. Composite materials like carbon fiber or lightweight metals like aluminum and
magnesium can be used to reduce weight.
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Hybrid maintenance:
Both the Honda and the Toyota have long warranties on the hybrid systems. The Insight
has an eight-year/80,000-mile warranty on most of the power train, including batteries,
and a three-year/36,000-mile warranty on the rest of the car. The Prius has an eightyear/100,000-mile warranty on the battery and hybrid systems and a three-year/36,000mile warranty on everything else. The motors and batteries in these cars don't require any
maintenance over the life of the vehicle. And the engine doesn't require any more
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maintenance than the one in any other car. And because both hybrids have regenerative
braking, the brake pads may even last a little longer than those in most cars.
You can get the best mileage from a hybrid car by using the same kind of driving habits
that give you better mileage in your gasoline-engine car:
Drive slower - The aerodynamic drag on the car increases dramatically the faster
you drive. For example, the drag force at 70 mph (113 kph) is about double that at 50 mph
(81 kph). So, keeping your speed down can increase your mileage significantly.
Maintain a constant speed - Each time you speed up the car you use energy, some
of which is wasted when you slow the car down again. By maintaining a constant speed,
you will make the most efficient use of your fuel.
Avoid abrupt stops - When you stop your car, the electric motor in the hybrid acts
like a generator and take some of the energy out of the car while slowing it down. If you
give the electric motor more time to slow the vehicle, it can recover more of the energy. If
you stop quickly, the brakes on the car will do most of the work of slowing the car down,
and that energy will be wasted.
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CONCLUSION
Using the concept of Hybridization of cars results in better efficiency and also
saves a lot of fuel in todays fuel deficit world. Though at present the concept has
been put in to maximum utilization by Honda & Toyota, it is indeed an important research
avenue for other car manufacturing units as well. A hybrid gives a solution to all the
problems to some extent. If proper research and development is done in this field,
hybrid vehicle promises a practical, efficient, low pollution vehicle for the coming
era. One can surely conclude that this concept and the similar ones to follow with even
better efficiency & conservation rate are very much on the anvil in todays energy deficit
world.
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REFERENCE
WWW.HOWSTUFFWORKS.COM
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