A PROJECT ON

“REGENERATIVE BRAKING SYSTEM”

SUBMITTED TO

GUJARAT TECHNOLOGICAL UNIVERSITY

AHMEDABAD

FOR PARTIAL FULFILLMENT OF

DIPLOMA ENGINEERING IN MECHANICAL DAPARTMENT

SUBMITTED BY

AJMERI AMIR HAIDARBHAI

PATEL BHARGAV KAMLESHBHAI

AGARWAL UMAKANT SATISKUMAR

DWIVEDI SHREEPRAKASH VINODKUMAR

DEPARTMENT OF MECHANICAL ENGG.

R.M.S. POLYTECHNIC, VADODARA

2013-2014

A PROJECT ON

“REGENERATIVE BRAKING SYSTEM”

FOR PARTIAL FULFILLMENT OF

DIPLOMA ENGINEERING IN MECHANICAL DAPARTMENT

YEAR 2012-2013

SUBMITTED BY

AJMERI AMIR HAIDARBHAI 106420319518

PATEL BHARGAV KAMLESHBHAI 106420319556

AGARWAL UMAKANT SATISKUMAR 106420319514

DWIVEDI SHREEPRAKASH VINODKUMAR 106420319527

GUIDED BY: - H.O.D

MR. DHAVAL JADHAV MR. DEVENDRA KUMAR PANDEY

MECHANICAL DEPT. MECHANICAL DEPT.

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R.M.S. POLYTECHNICCERTIFICATE

This is to verify that the “IDP” entitled “REGENERATIVE BRAKING SYSTEM” to the department of MECHANICAL ENGG. RMS

POLYTECHNIC, VADODARA is bonafied work carried out by the candidate during the period “June 2012 to May 2013” under the guidance

of undersigned .it is further certified that the work reported in the “IDP” fulfils the requirement of the ordinance related to the diploma in

MECHANICAL ENGG. FROM GTU, AHMEDABAD

GUIDED BY: H.O.D. MR DHAVAL JADHAV MR DEVENDRA KUMAR PANDEY MECHANICAL DEPARTMENT MECHANICAL DEPARTMENT RMS POLYTECHNIC RMS POLYTECHNIC

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DECLARATION

I hereby declare that major project entitled “regenerative braking system” is the result of our team work .The project has not accepted for any degree and is not concurrently submitted in candidature of any other diploma.

Name: - Signature

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Acknowledgement

Every work that one completes successfully stands on the constant encouragement, good will & support of the people around.

We would like to express my sincere appreciation to our project guide Mr DHAVAL JHADHAV & Head of the Department Mr DEVANDRA PANDEY for his encouragement, guidance & constant support. Without his continued support and insights throughout this work, this project could not have been

realized.

We would like to acknowledge with many thanks to our principal Mr Jaydeepsinh Parmar their enthusiasm, guidance & encouragement have

been in valuable to this project.

We would like to thanks all the other faculty members & staff of the department for their directly or indirectly support.

We also thanks all my friends and whoever involved directly or indirectly in making this project successful.

Our most thanks to my family for their caring encouragement and moral support throughout my academic year.

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OBJECTIVE

To design a model of regenerative braking system, which can be implemented in electric cars and automobiles and in electric locomotives in order to improve the efficiency of vehicles by 20to 30%?

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CONTENTS1. ABSTRACT2. INTRODUCTION & PROSPECTS3. OVERVIEW OF REGENERATIVE BRAKING SYSTEM4. WORKING PRINCIPLE

1. REGENERATIVE WORKING2. HOW DOES A MOTOR/GENERATOR WORK IN AN ELECTRIC OR HYBRID

VEHICLE?3. PROPELLING THE VEHICLE WITH THE M/G4. REGENERATIVE BRAKING: SLOWING THE VEHICLE AND GENERATING

ELECTRICITY5. MODE OF POWER GENERATION5.1 ELECTROMAGNETISM6. PARTS OF REGENERATIVE BRAKING SYSTEM / UDP

1. ALTERNATOR2. FLYWHEEL 3. BEARING 4. PULLEY 5. CLUTCH DISC6. LIGHT(BULB)7. MAIN FRAME WITH MOTOR STAND 8. MAIN SHAFT9. MOTOR 10.CHAIN 11.SPROCKET 12.RUBBER SHEET13.STORAGE BATTERY/DYNAMO

7. TYPES OF BRAKING1. DISC BRAKES2. DRUM BRAKES3. HYDRAULIC BRAKES4. ELECTROMAGNETIC BRAKES5. ABS BRAKES

8 FUTURE OF REGENERATIVE BRAKING SYSTEM9 SCOPES IN AUTO VEHICLES10 APPLICATIONS11 SCOPES IN DELHI METRO12 NEED OF REGENERATIVE BRAKING IN METRO13 EFFIECINCY14 CONCLUSIONS15 REQUIREMENT ANALYSES16 REFERENCES

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ABSTRACTWhen we apply brake in the vehicles to stop its motion a considerable amount of kinetic energy is lost in the form of heat and friction. So to regain and save this energy we use regenerative brake system which will regain the electrical energy at the time of braking and stored in the battery.

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INTRODUCTION& PROSPECTSRegenerative braking is used in vehicles that make use of electric motors,

primarily fully electric vehicles and hybrid electric vehicles. One of the more interesting properties of an electric motor is that, when it's run in one direction, it converts electrical energy into mechanical energy that can be used to perform work (such as turning the wheels of a car), but when the motor is run in the opposite direction, a properly designed motor becomes an electric generator, converting mechanical energy into electrical energy. This electrical energy can then be fed into a charging system for the car's batteries

Regenerative braking is used in vehicles that make use of electric motors, primarily fully electric vehicles and hybrid electric vehicles. One of the more interesting properties of an electric motor is that, when it's run in one direction, it converts electrical energy into mechanical energy that can be used to perform work (such as turning the wheels of a car), but when the motor is run in the opposite direction, a properly designed motor becomes an electric generator, converting mechanical energy into electrical energy. This electrical energy can then be fed into a charging system for the car's batteries. Once the motor has been reversed, the electricity generated by the motor is fed back into the batteries, where it can be used to accelerate the car again after it stops. Sophisticated electronic circuitry is necessary to decide when the motor should reverse, while specialized electric circuits route the electricity generated by the motor into the vehicle's batteries. In some cases, the energy produced by these types of brakes is stored in a series of capacitors for later use. In addition, since vehicles using these kinds of brakes also have a standard friction braking system, the vehicle's electronics must decide which braking system is appropriate at which time. Because so much is controlled electronically in a regenerative braking system, it's even possible for the driver to select certain presents that determine how the vehicle reacts in different situations. For instance, in some vehicles a driver can select whether regenerative braking should begin immediately or not.

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OVERVIEW OF REGENERATIVE BRAKING SYSTEMRegenerative braking system is a technology that can be implemented with all the vehicles in order to improve its efficiency and saving power. this technology was first discovered by Toyota motors in 2004.this technology is limited in its application now a days, but in future it may be widely find its application in all type of automobile and locomotives in terms of regenerative braking, means capturing the vehicle's momentum (kinetic energy) and turning it into electricity that recharges (regenerates) the on board battery as the vehicle is slowing down and/ or stopping. It is this charged battery that in turn powers the vehicle's electric traction motor. In an all-electric vehicle, this motor is the sole source of locomotion. In a hybrid, the motor works in partnership with an internal combustion engine. But that motor is not Must a source of propulsion, it's also a generator.

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WORKING PRINCIPLERegenerative working Hybrids and all-electric vehicles create their own power for battery recharging through a process known as regenerative braking (regen mode). We've explained what regenerative braking is and how the process works in general terms, but many folks are interested in the deeper nuts and bolts of electricity generation. They understand that in a hybrid or all-electric vehicle the word "regenerative," in terms of regenerative braking, means capturing the vehicle's momentum (kinetic energy) and turning it into electricity that recharges (regenerates) the on board battery as the vehicle is slowing down and/or stopping. It is this charged battery that in turn powers the vehicle's electric traction motor. In an all-electric vehicle, this motor is the sole source of locomotion. In a hybrid, the motor works in partnership with an internal combustion engine. But that motor is not Must a source of propulsion, it's also a generator. Any permanent magnet motor can operate as either a motor or generator. In all-electrics and hybrids, they are more precisely called a motor/generator (M/G). But the technologically curious want to know more, and they'll often ask "How, and by what mechanism or process, is the electricity created?" It's a good question, so before we get started explaining how M/G and regenerative braking work in hybrids and electric vehicles, it is important to have basic knowledge about how electricity is generated and how a motor/generator functions. Take a minute to read How Motors and Generators Work and then come back for the low-down on the regenerative braking process.

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HOW DOES A MOTOR/GENERATOR WORK IN AN ELECTRIC OR HYBRID VEHICLE No matter the vehicle design, there must be a mechanical connection between the M/G and the drive train. In an all-electric vehicle there could be an individual M/G at each wheel or a central M/G connected to the drive train through a gearbox. In a hybrid, the motor/generator could be an individual component that is driven by an accessory belt from the engine (much like an alternator on a conventional vehicle--this is how the GM BAS system works), it could be a pancake M/G that is bolted between the engine and transmission (this is the most common setup-- the Prius, for example), or it could be multiple M/G mounted inside the transmission (this is how the two-modes work). In any case, the M/G has to be able to propel the vehicle as well as be driven by the vehicle in regen mode.

PROPELLING THE VEHICLE WITH THE M/ GMost, if not all, hybrids and electrics use an electronic throttle control system. When the throttle pedal is pushed, a signal is sent to the on board computer, which further activates a relay in the controller that will send battery current through an inverter/converter to the M/G causing the vehicle to move. The harder the pedal is pushed, the more current flows under direction of a variable resistance controller and the faster the vehicle goes. In a hybrid, depending upon load, battery state-of-charge and the design of the hybrid drive train, a heavy throttle will also activate the internal combustion engine (ICE) for more power. Conversely, lifting slightly on the throttle will decrease current flow to the motor and the vehicle will slow down. Lifting further or completely off the throttle will cause the current to switch direction--moving the M/G from motor mode to generator mode--and begin the regenerative braking process.

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REGENERATIVE BRAKING: SLOWING THE VEHICLE AND GENERATING ELECTRICITYThis is really what the regen mode is all about. With the electronic throttle closed and the vehicle still moving, all of its kinetic energy can be captured to both slow the vehicle and recharge its battery. As the on board computer signals the battery to stop sending electricity (via the controller relay) and start receiving it (through a charge controller), the M/G simultaneously stops receiving electricity for powering the vehicle and starts sending current back to the battery for charging. Remember from our discussion on electromagnetism and motor/ generator action: when an M/G is supplied with electricity it makes mechanical power, when it's supplied with mechanical power, it makes electricity. But how does generating electricity slow the vehicle? Friction. It's the enemy of motion. The armature of the M/G is slowed by the force of inducing current in the windings as it passes over the opposing poles in the magnets in the stator (it's constantly battling the push/pull of the opposing polarities). It is this magnetic friction that slowly snaps the vehicle's kinetic energy and helps to brake it.

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MODE OF POWER GENERATIONELECTROMAGNETISMMotor power and electricity generation begin with the property of electromagnetism—the physical relationship between a magnet and electricity. An electromagnet is a device that acts like a magnet, but its magnetic force is manifested and controlled by electricity. When wire made of conducting material (copper, for example) moves through a magnetic field, current is created in the wire (a rudimentary generator). Conversely, when electricity is passed through a wire that is wound around an iron core, and this core is in the presence of a magnetic field, it will move and twist (a very basic motor).

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PARTS OF REGENERATIVEBRAKING SYSTEMFollowings are the parts of regenerative brake system

1. Alternator

2. Flywheel

3. Bearing

4. Pulley

5. Clutch disc

6. Light(bulb)

7. Main frame with motor stand

8. Main shaft

9. Motor

10. Chain

11. Sprocket

13. Rubber sheet

14. Storage battery/dynamo

1.

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Requirement analysis Following are the required components with their specifications

1. ALTERNATOR

Principle:A.C. generators or alternators (as they are usually called) operate on the

same fundamental principles of electromagnetic induction as D.C. generators.

Alternating voltage may be generated by rotating a coil in the magnetic field or by rotating a magnetic field within a stationary coil. The value of the voltage generated depends on-

• The number of turns in the coil.

• Strength of the field.

• The speed at which the coil or magnetic field rotates.

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2. FLYWHEEL

15cm * 3.81cm width

A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.

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3. BEARING

2 nos.

Ball bearing dia: 2.5cm A bearing is a machine element that constrains relative motion between moving parts to only the desired motion. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts

4. PULLEY

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A pulley is a wheel on an axle that is designed to support movement of a cable or belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power.

3.81cm width

v- groove

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5. CLUTCH DISC

clutch disc dia: 9cm

A clutch is a mechanical device that provides for the transmission of power (and therefore usually motion) from one component (the driving member) to another (the driven member) when engaged, but can be disengaged.Clutches are used whenever the transmission of power or motion must be controlled either in amount or over time

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6. LIGHT (BULB)

7. MAIN FRAME

8. MAIN SHAFT

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Length 18.5 inch

Dia… 1.7 inch

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9. MOTOR

Type: dc motor

No load speed: 900 rpm

Power 0.25 Hp single phase

AC motor, an electric motor that is driven by alternating current

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10. CHAIN

Roller chain

12.7mm*3.2mm*110/112links

Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic ,industrial and agricultural machinery, including conveyors, wire-and tube-drawing machines, printingpresses, cars, motorcycles, and bicycles. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission.

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11. SPROCKET

Pitch ½ inch

Width 1/8 inch

Teeth 18

Sprockets are used in bicycles, motorcycles, cars, tracked vehicles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc.

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12. RUBBER SHEET

13. OUTPUT CURRENT Output current: 75 mille amp

Output voltage: 12 volt dc

14. BATTERY

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TYPES OF BRAKING▪Disc brakes

▪Drum brakes

▪Hydraulic brakes

▪Electromagnetic brakes

▪Abs brakes

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DISC BRAKEThe disc brake is a device for slowing or stopping the rotation of a wheel. A brake disc (or rotor in usually made of cast iron or ceramic composites (including carbon, Kevlar and silica), is connected to the wheel and/or the axle. To stop the wheel, friction material in the form of brake pads (mounted on a device called a brake calliper) is forced mechanically, hydraulically, pneumatically or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop.

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DRUM BRAKESThe drum brake has been more widely used than any other brake design. Braking power is obtained when the brake shoes are pushed against the inner surface of the drum which rotates together with the axle.

Drum brakes are used mainly for the rear wheels of passenger cars and trucks while disc brakes are used exclusively for front brakes because of their greater directional stability.

The backing plate is a pressed steel plate, bolted to the rear axle housing. Since the brake shoes are fitted to the backing plate, all of the braking force acts on the backing plate. Drum Brakes are now used mainly for the rear wheels of passenger cars and trucks.

When the brake pedal is depressed while the vehicle is moving backward, the brake shoes expand and contact the drum. The shoes are forced by the drum to begin rotating; however, the upper end of No. 1 shoe is wedged against the anchor pin. Since No. 2 shoe is moving away from the anchor

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pin, it causes the adjusting lever to pivot and turn the shoe adjusting screw and reduce the clearance. If clearance is proper, the adjusting lever will not engage the tooth of the adjusting screw.

The shoe adjusting screw consists of a bolt and two nuts as shown below. The bolt end is marked with an R" or L" to indicate which side of the vehicle it is mounted on.

HYDRAULIC BRAKESThe hydraulic brake system used in the automobile is a multiple piston system. A multiple piston system allows forces to be transmitted to two or more pistons in the manner indicated in figure 2-21. Note that the pressure set up by the force applied to the input piston (1) is transmitted undiminished to both output pistons (2 and 3), and that the resultant force on each piston is proportional to its area. The multiplication of forces from the input piston to each output piston is the same as that explained earlier.

The hydraulic brake system from the master cylinders to the wheel cylinders on most automobiles operates in a way similar to the system illustrated in figure 2-22.

Multiple piston system.When the brake pedal is depressed, the pressure on the brake pedal moves the piston within the master cylinder, forcing the brake fluid from the master cylinder through the tubing and flexible hose to the wheel cylinders. The wheel cylinders contain two opposed output pistons, each of which is attached to a brake shoe fitted inside the brake drum. Each output piston pushes the attached brake shoe against the wall of the brake drum, thus retarding the rotation of the wheel. When pressure on the pedal is released, the springs on the brake shoes return the wheel cylinder pistons to their released positions. This action forces the displaced brake fluid back through the flexible hose and tubing to the master cylinder.

The force applied to the brake pedal produces a proportional force on each of the output pistons, which in turn apply the brake shoes frictionally to the turning wheels to retard rotation. As previously mentioned, the hydraulic brake system on most automobiles operates in a similar way, as shown in

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figure 2-22. It is beyond the scope of this manual to discuss the various brakes Systems.

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An automobile brake system.

ELECTROMAGNETIC BRAKESElectromechanical braking systems (EMB), also referred to as brake by-wire, replace conventional hydraulic braking systems with a completely “dry” electrical component system. This occurs by replacing conventional actuators with electric motor driven units. This move to electronic control eliminates many of the manufacturing, maintenance, and environmental concerns associated with hydraulic systems.

Electromechanical braking systems (EMB), also called brake by-wire, replace conventional hydraulic braking systems with completely “dry” electrical component systems by replacing conventional actuators with electric motor-driven units. This move to electronic control eliminates many of the manufacturing, maintenance, and environmental concerns associated with hydraulic systems.

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ABS BRAKING SYSTEMAntilock braking system that is between the brake master cylinder and the wheels. The system prevents an unstable condition of the car under extreme braking conditions. It modulates the pressure of the brake fluid that is applied to both front brake callipers and/or both rear callipers, preventing the wheels from "LOCKING UP". Normal brake fluid pressure is restored when there is no longer a possibility of the wheels locking up. Each wheel has a SENSOR that the system monitors for each wheels rotation. If one of the wheels is turning slower than the others, the anti-lock system releases the pressure to that wheel. The system is designed to provide positive feedback by way of a kickback on the brake pedal when the system has been activated. The system works very well in wet or icy conditions, preventing skids and loss of directional control. The ABS computer controls all functions of the antilock brakes. If there is a problem with the ABS system, the ABS INDICATOR LIGHT on the dash illuminates. Have the car checked out immediately. In the event of a failure of the antilock brake system, it does have a fail-safe function that allows for normal braking.

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Hydraulic ABS BrakingThe purpose of ABS is to optimize the braking effectiveness and maintain vehicle stability under various road conditions. It is achieved by controlling the slip ratio at the point where maximum braking force can be applied to the wheels.

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FUTURE OF REGENERATIVE BRAKING SYSTEMRegenerative braking system will be used further in all the cars, trucks, electric cars and in electric locomotive also. Besides regaining the electrical energy it also increasing the effort of braking to control the wheel from skid.

Regenerative braking system increase the efficiency by

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SCOPE IN AUTO VEHICLES

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APPLICATIONS The energy efficiency of a conventional car is only about 20 per cent,

with the remaining 80 per cent of its energy being converted to heat through friction. The miraculous thing about regenerative braking is that it may be able to capture as much as half of that wasted energy and put it back to work. This could reduce fuel consumption by 10 to 25 per cent. Hydraulic regenerative braking systems could provide even more impressive gains, potentially reducing fuel use by 25 to 45 per cent [source: In a century that may see the end of the vast fossil fuel reserves that have provided us with energy for automotive and other technologies for many years, and in which fears about carbon emissions are coming to a peak, this added efficiency is becoming increasingly important.

The beginning of the 21st century could very well mark the final period in which internal combustion engines are commonly used in cars. Already automakers are moving toward alternative energy carriers, such as electric batteries, hydrogen fuel and even compressed air. Regenerative braking is a small, yet very important, step toward our eventual independence from fossil fuels. These kinds of brakes allow batteries to be used for longer periods of time without the need to be plugged into an external charger. These types of brakes also extend the driving range of fully electric vehicles. In fact, this technology has already helped bring us cars like the Tesla Roadster, which runs entirely on battery power. Sure, these cars may use fossil fuels at the recharging stage -- that is, if the source of the electricity comes from a fossil fuel such as coal -- but when they're out there on the road, they can operate with no use of fossil fuels at all, and that's a big step forward.

The added efficiency of regenerative braking also means less pain at the pump, since hybrids with electric motors and regenerative brakes can travel considerably farther on a gallon of gas, some achieving more than 50 miles per gallon at this point. And that's something that most drivers can really appreciate.

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SCOPE IN DELHI METROTraction accounts for about 60-80% of total energy consumption in a Metro system. The quantity of energy consumed by trains is influenced by a wide range of factors, design of train being one of them. Hence, optimization of overall system design in order to control consumption of electricity becomes essential. The modern design of Metro Rolling Stock incorporating three phase induction motors and Converter Inverter enables recovery of a major portion of consumed electricity by way of using regenerative braking. Metro railways worldwide have reported an average of about 20% saving in traction energy on account of regeneration. It also helps to reduce heat load inside tunnel and thus reduce air Conditioning load. With increased awareness and commitment for environment metros have also taken it as Green House Gas reduction initiative. Regenerated energy is mostly used by other trains powering in the network. The quality of regenerated power is important since the injected harmonics effect signalling, communication system and other loads connected on the grid.

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NEED OF REGENERATIVE BRAKING SYSTEM IN METROWith smaller inter-station distances, Metro operation is essentially of start/stop nature. Due to frequent acceleration & de-acceleration requirements, energy demand is very high. Traction accounts for about 60-80% of total energy consumption in a Metro system. The quantity of energy consumed by trains is influenced by a wide range of factors, which can be grouped as

(i) Design of network,

(ii) Design of trains &

(iii) Service planning operation. Hence, optimization of overall system design in order to control consumption of electricity becomes essential.

The scope of this paper is limited to one of design aspect of trains i.e. regenerative braking. The modern design of Metro Rolling Stock incorporating three phase induction motors and Converter Inverter enables recovery of a major portion of consumed electricity by way of using regenerative braking. Metro railways worldwide have reported an average of about 20% saving on account of regeneration. By using intelligent blending of regenerative and pneumatic braking, optimization of energy recovery as well as accurate control of train movement can be achieved. In addition to saving of electricity, regenerative braking provides additional benefits in form of lesser wear of wheel and brake pads. In Metro applications, there is likelihood of having a considerable area of underground operation. $n efficiently employed regenerative braking system helps to reduce heat load inside tunnel and thus reduce air Conditioning load. Needless to mention that regenerative braking helps in mitigating Global Warming by way of reducing carbon emissions due to reduced electricity requirements from grid.

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CONCLUSIONEFFIECINCY

The regenerative braking system can be successfully implemented with the electric cars and electric locomotives. The energy efficiency of a conventional car is only about 20 per cent, with the remaining 80 per cent of its energy being converted to heat through friction. The miraculous thing about regenerative capture as much as half of that wasted energy and put it back to work. This could reduce fuel consumption by 10 to 25 per cent. Hydraulic regenerative braking systems could provide even more impressive gains, potentially reducing fuel use by 25 to 45 per cent in a century that may see the end.

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REFERENCES

Google.com

Wikipedia

how stuff work.com

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