regenerative breaking

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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
http://timesofindia.indiatimes.com/topic/Switzerlandhttp://timesofindia.indiatimes.com/topic/Switzerlandhttp://timesofindia.indiatimes.com/topic/Switzerlandhttp://timesofindia.indiatimes.com/topic/Switzerland


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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.

regenerative breaking

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