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DEGREE engineering college,CHANDIPADAR ,(Berhampur)
Seminar report on Regenerative Braking SystemMECHANICAL ENGINEERING
Submitted byAbhishek kumar mishra
Regd.No.-0801220287 ( 8th SEM.)
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BONAFIDE CERTIFICATE
This is to certify that the student ABHISHEK KUMAR MISHRA
of Mechanical Engineering have undergone the live seminar on
Regenerative Braking System and has prepared this seminar
report by virtue of his diligence adherence and advice.
He has successfully completed every aspect of this seminar with a
lot of sincerity and devotion during the seminar was very muchappreciating
.
We wish him all success for bright future.
Er.Ritanjali Panda Dr. J.K.Sahu
(Seminar guide) (HOD E&TC)
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acknowledgementI am grateful to my seminar guide ER. RITANJALI
PANDA for his able guidance and constructive
criticism.
I also owe my gratitude to Dr. J.K.SAHU and all the
faculty members of our branch for their kind
cooperation during the seminar framing period.
Last but not the least I am extremely thankful to
my friends for their support during the preparation of
seminar.
Signature of Student
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CONTENTS
ABSTRACTINTRODUCTIONNECCESITY OF REGEN. BRAKINGHOW IT WORKSREGEN. IN RAIL VEHICLESREGEN. IN ROAD VEHICLESBENEFITS AND DOWNSIDES OF
REGEN. BRAKING
CONCLUSION
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ABSTRACTRegenerative Braking System is the way of
slowing vehicle by using the motors as brakes.
Instead of the surplus energy of the vehicle
being wasted as unwanted heat, the motors act
as generators and return some of it to the
overhead wires as electricity.
The vehicle is primarily powered from the
electrical energy generated from the generator,
which burns gasoline. This energy is stored in a
large battery, and used by an electric motor that
provides motive force to the wheels. The
regenerative barking taking place on the vehicle
is a way to obtain more efficiency; instead of
converting kinetic energy to thermal energy
through frictional braking, the vehicle can
convert a good fraction of its kinetic energy
back into charge in the battery, using the same
principle as an alternator.
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INTRODUCTION
Brake:-
A brake is a machine element and its
principle object is to absorb energy during
deceleration. In vehicle brakes are used to
absorb kinetic energy whereas in hoists or
elevators brakes are also used to absorb
potential energy. By connecting the moving
member to stationary frame, normally brake
converts kinetic energy to heat energy. This
causes wastage of energy and also wearing of
frictional lining material .
Regenerative Braking System:-
Regenerative Braking System is the way of
slowing vehicle by using the motors as brakes.
Instead of the surplus energy of the vehicle
being wasted as unwanted heat, the motors act
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as generators and return some of it to the
overhead wires as electricity.
The vehicle is primarily powered from the
electrical energy generated from the generator,
which burns gasoline. This energy is stored in a
large battery, and used by an electric motor that
provides motive force to the wheels. The
regenerative braking taking place on the vehicle
is a way to obtain more efficiency; instead of
converting kinetic energy to thermal energy
through frictional braking, the vehicle can
convert a good fraction of its kinetic energy
back into charge in the battery, using the same
principle as an alternator.
Therefore, if you drive long distance without
braking, youll be powering the vehicle entirely
from gasoline.
Regenerative Braking System comes into its own
when youre driving in the city, and spending a
good deal of your time braking.
You will still use more fuel in the city for each
mile you drive than on the highway, though.
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(Thermodynamics tells us that all inefficiency
comes from heat generation. For instance, when
you brake, the brake pedals heat up and a
quantity of heat, or energy, is lost to the outside
world. Friction in the engine produces heat in
the same way.
Heat energy, also, has higher entropy than, say,
electric, meaning that it is less ordered.)
Definition:
Braking method in which the mechanical energy
from the load is converted into electric energy
and regenerated back into the line is known as
Regenerative Braking. The Motor operates as
generator.
NECESSITY OF THE SYSTEM
The regenerative braking system delivers a
number of significant advantages over a car that
only has friction brakes. In low-speed, stop-and-
go traffic where little deceleration is required;
the regenerative braking system can provide the
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majority of the total braking force. This vastly
improves fuel economy with a vehicle, and
further enhances the attractiveness of vehicles
using regenerative braking for city driving. At
higher speeds, too, regenerative braking has
been shown to contribute to improved fuel
economy by as much as 20%.
Consider a heavy loaded truck having very
few stops on the road. It is operated near
maximum engine efficiency. The 80% of the
energy produced is utilized to overcome the
rolling and aerodynamic road forces. The energy
wasted in applying brake is about 2%. Also its
brake specific fuel consumption is 5%.
Now consider a vehicle, which is operated in
the main city where traffic is a major problem
here one has to apply brake frequently. For such
vehicles the wastage of energy by application of
brake is about 60% to 65%. And also it is
inefficient as its brake specific fuel consumption
is high.
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HOW IT WORKS
Regenerative (or Dynamic Braking) occurs when
the vehicle is in motion, such as coasting,
traveling downhill or braking. And the
accelerator pedal is not being depressed. During
Regent, the motor becomes a generator and
sends energy back to the batteries.
It is explained as follows, because the
wheels of a decelerating vehicle are still moving
forward, they can be made to turn the electric
motor, which then feeds energy to the batteries
for storage. The system becomes, in effect, a
generator, which provides braking force while it
converts the vehicles kinetic energy into a
reusable form- electrical energy.
When the accelerator pedal is released, the
absence of pressure triggers a response from the
Energy Storage Unit (ESU). Regenerative
braking begins, and the batteries are re-charged
by the motor, which is turned by the wheels. In
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this case, the friction brakes are not engaged.
If more vigorous deceleration is required, and
the brake pedal is depressed, this engages both
sets of brakes. However, to maximize energy
efficiency, it is advantageous to apply the
regenerative brake as such as possible it
therefore tends to do more of its total work in
the first part of the braking motion.
There are two deceleration modes:
1. Foot off throttle but not on brake pedal in
this mode, the charge/assist gauge will show
partial charge, and the vehicle will slow down
gradually.
2. Foot on brake pedal - In this mode, a higher
amount of regeneration will be allowed, and the
vehicle will slow more rapidly. During light
brake pedal application, only the IMA
motor/ /generator is slowing the car. With
heavier brake pedal application, the
conventional friction brakes also come into play.
When decelerating, regeneration will continue
u8ntil engine speed falls to about 1000 rpm. At
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this point, the driver will typically shift into
neutral.
DIAGRAM OF A REGEN. BRAKING SYSTEM
REGEN. BRAKING IN RAIL VEHICLES
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Dynamic Braking has been frequently used inrail vehicles to reduce brake wear:
Dynamic braking is the use of the electrictraction motors
of a vehicle as generators when slowing. It is termed
rheostaticif the generated electrical power is dissipated
as heat in brake grid resistors, andregenerativeif the
power is returned to the supply line. Dynamic braking
lowers the wear offriction-based braking components,
and additionally regeneration reduces energy
consumption.
Traction motor refers to anelectric motorproviding the
primary rotational torque of a machine, usually for
conversion intolinear motion(traction).
Some electric rail/overhead line locomotiveswith regenerative braking can send power
back through supply line:
A regen. braking system used by locomotives and trains
fitted with electric traction motors where the motors
become generators and the current developed is fed into
the overhead line or third rail for use by other trains or for
return to the supplier.When the driver of a train wants to stop orslow down a train, he applies regenerative braking. The motors of
the locomotives which are normally pulling the train, change their
mode of operation from motor to a generator. The mechanical
energy of the train is converted to electrical energy by the
generator, which then goes to the power supply grid. This feature is
called regenerative braking. Thus, even braking losses are gainfully
utilised in three phase locomotives.
http://en.wikipedia.org/wiki/Traction_motorshttp://en.wikipedia.org/wiki/Traction_motorshttp://en.wikipedia.org/wiki/Traction_motorshttp://en.wikipedia.org/wiki/Regenerative_brakehttp://en.wikipedia.org/wiki/Regenerative_brakehttp://en.wikipedia.org/wiki/Regenerative_brakehttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Linear_motionhttp://en.wikipedia.org/wiki/Linear_motionhttp://en.wikipedia.org/wiki/Linear_motionhttp://en.wikipedia.org/wiki/Traction_%28engineering%29http://en.wikipedia.org/wiki/Traction_%28engineering%29http://en.wikipedia.org/wiki/Traction_%28engineering%29http://en.wikipedia.org/wiki/Traction_%28engineering%29http://en.wikipedia.org/wiki/Linear_motionhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Regenerative_brakehttp://en.wikipedia.org/wiki/Traction_motors -
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Pointedly, over the years, the technology upgradation has taken
place in electric locomotives, which has contributed in overall
objective of Railways to conserve precious electric energy. With
this objective in mind, 3 phase locomotives were inducted into
Railways almost 15 years ago. Initially, these locomotives wereimported fromSwitzerlandon ToT basis (Transfer of Technology).
As per this agreement, when complete equipment is imported, the
foreign company also undertakes to transfer the entire knowhow to
the indigenous company for enabling the latter to manufacture the
imported equipment in the country. After 5 years, CLW (Chitranjan
Locomotives Works) started the production of three phase
locomotive indigenously gradually reducing the import content to
5% only.
North Central Railway runs around 250 passenger trains
and 150 trains every day by electric locomotives. Out of
these, about 25% of trains are run by about three phase
locomotives. Since drivers running such locomotives were
required to be given special training to utilise this feature,
NCR has trained all its drivers to utilise regenerative
braking. Due to intelligent application of this feature, NCR
has saved about 15 million units of electricity costing Rs 6
crores.
REGEN. BRAKING IN ROAD VEHICLE
Hydraulic Regenerative Braking (HRB) has already been
proposed for Heavy Duty Trucks [4] to recover the braking
energy with a high efficiency on a regenerative loop. When
the driver steps on the brake, the vehicle's kinetic energy
powers a reversible pump, which sends hydraulic fluid
from a low pressure reservoir inside the vehicle into a high
pressure accumulator. The pressure is created by
compressing nitrogen gas in the accumulator as the fluid
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is pumped in to displace the nitrogen. This slows the
vehicle and helps bringing it to a stop.
The fluid remains under pressure in the accumulator until
the driver pushes the accelerator again. Then the pumpreverses and the pressurized fluid is used to accelerate
the vehicle, effectively translating the kinetic energy that
the truck had before braking into mechanical energy that
helps to speed up the vehicle again. It is predicted that a
system like this could store 80% of the momentum lost by
a vehicle during deceleration and use it to get the vehicle
moving again. Actual regenerative cycle efficiencies are
probably smaller than that.So far, HRB systems have been
used primarily as proofs of concept and in demonstration
projects only. They are not ready for production models.
These hydraulic brakes are noisy and prone to leaks and
the accumulators take up a considerable amount of space.
Once all of these issues are solved, such systems will
probably be most useful in large trucks weighing 4,500
kilograms or more, where hydraulic brakes may prove to
be a more optimal system than much less efficient
electronically controlled regenerative brakes.
CARS WITH REGEN. BRAKING
Toyota Prius Honda Insight Ford Escape Hybrid Tesla Roadster Chevy Volt
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TYOTA PRIUS
BENEFITS OF REGEN. BRAKING
Energy Conservation:
The flywheel absorbs energy when braking via a
clutch system slowing the car down and
speeding up the wheel. To accelerate, another
clutch system connects the flywheel to the drive
train, speeding up the car and slowing down the
flywheel. Energy is therefore conserved rather
than wasted as heat and light which is what
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normally happens in the contemporary shoe/disc
system.
Wear Reduction:
In regenerative raking, when the motor is not
receiving power from the battery pack, it resists
the turning of the wheels, capturing some of the
energy of motion as if it were a generator and
returning that energy to the battery pack. In
mechanical brakes; lessening wear and
extending brake life is not possible. This
reduces the use of use the brake.
Fuel Consumption:
The fuel consumption of the conventional
vehicles and regenerative braking system
vehicles was evaluated over a course of various
fixed urban driving schedules. The results are
compared as shown in figure. Representing the
significant cost saying to its owner, it has been
proved the regenerative braking is very fuel-
efficient.
Braking is not total loss:
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Conventional brakes apply friction to convert a
vehicles kinetic energy into heat. In energy
terms, therefore, braking is a total loss: once
heat is generated, it is very difficult to reuse.
The regenerative braking system, however,
slows a vehicle down in a different way.
DOWNSIDES
Added complexity of brake control system Only works for wheels connected to motors Friction brakes are still necessary
CONCLUSION
Theoretical investigations of a regenerative
braking system show about 25% saving in fuel
consumption.
The lower operating and environment costs of
a vehicle with regenerative braking system
should make it more attractive than a
conventional one. The traditional cost of the
system could be recovered in the few years only.
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The exhaust emission of vehicle using the
regenerative braking concept would be much
less than equivalent conventional vehicles as
less fuel are used for consumption.
These systems are particularly suitable in
developing countries such as India where buses
are the preferred means of transportation within
the cities.