NOTES

1. 1
CHAPTER-1
INTRODUCTION
In the effort to produce greener cars numerous processes have been examined that effect
fuel consumption. One process is braking - traditional braking wastes energy because it
kills the momentum that the engine has built up. However, with the process of
regenerative braking, this energy effectively finds a new home. Instead of being lost as
heat in the brakes, the energy is used to drive an alternator which allows the energy to be
partially recovered and stored in a battery. In conventional vehicles this stored energy is
then used to power electrical components including headlights, stereos and air
conditioning.
In hybrid cars, regenerative braking is used to charge the battery that propels the electric
motor. This is particularly advantageous in town driving situations when cars
traditionally travel at low speeds. With regenerative braking a hybrid can rely solely on
the electric motor in these situations, therefore producing zero emissions. Regenerative
braking is sometimes confused with dynamic braking but the processes are very different.
By contrast, dynamic braking dissipates the energy as heat and does not recapture it.
1.1 Need
As in today’s world, where there are energy crises and the resources are depleting at a
higher rate, there is a need of specific technology that recovers the energy, which gets
usually wasted .So, in case of automobiles one of these useful technology is the
regenerative braking system. Generally in automobiles whenever the brakes are applied
the vehicle comes to a halt and the kinetic energy gets wasted due to friction in the form
of kinetic energy .Using regenerative braking system in automobiles enables us to
recover the kinetic energy of the vehicle to some extent that is lost during the braking
process. In this paper the author discusses two methods of utilizing the kinetic energy that
is usually wasted by converting it into either electrical energy or into mechanical energy.
Regenerative braking system can convert the kinetic energy into electrical energy with
help of electric motor. And it can also convert the kinetic energy into mechanical energy,
which is supplied to the vehicle whenever it is needed, with the help of electromagnetic
clutch
1.2 Regenerative Braking.
Regenerative braking means reduce losses and regenerate power by using mechanical
structure. Systems use friction to counteract the forward momentum of a moving car. As

2. 2
the brake pads rub against the wheels (or a disc connected to the axle), excessive heat
energy is also created. This heat energy dissipates into the air, wasting up to 30% of the
car's generated power. Over time, this cycle of friction and wasted heat energy reduces
the car's fuel efficiency. More energy from the engine is required to replace the energy
lost by braking.
Hybrid gas/electric automobiles now use a completely different method of braking at
slower speeds. While hybrid cars still use conventional brake pads at highway speeds,
electric motors help the car brake during stop-and-go driving. As the driver applies the
brakes through a conventional pedal, the electric motors reverse direction. The torque
created by this reversal counteracts the forward momentum and eventually stops the car.
But regenerative braking does more than simply stop the car. Electric motors and electric
generators (such as a car's alternator) are essentially two sides of the same technology.
Both use magnetic fields and coiled wires, but in different configurations. Regenerative
braking systems take advantage of this duality. Whenever the electric motor of a hybrid
car begins to reverse direction, it becomes an electric generator or dynamo. This
generated electricity is fed into a chemical storage battery and used later to power the car
at city speeds.
Regenerative braking takes energy normally wasted during braking and turns it into
usable energy. It is not, however, a perpetual motion machine. Energy is still lost through
friction with the road surface and other drains on the system. The energy collected during
braking does not restore all the energy lost during driving. It does improve energy
efficiency and assist the main alternator.

3. 3
CHAPTER-2
REVIEW OF LITERATURE
Background of Regenerative Braking System With Automatic Braking. Work machines,
such as wheel loaders, are employed to perform work, such as digging, lifting, and
moving large objects, in the agricultural, construction, and forestry related industries.
Each work machine is typically powered by engine, such as a diesel engine, which
operates a hydraulic system, a steering system, and a transmission for use in moving to
and from the work site, moving around the worksite, and in performing the tasks
designated for the work machine.
It is becoming increasingly important to improve the fuel efficiency of work machines,
and hence thereby reduce the cost of operating a work machine, as well as to reduce
engine emissions from the work machine. However, the cost of additional systems to
improve fuel efficiency and reduce emissions output may be prohibitive. It is therefore
desirable to improve efficiency and reduce emissions using primarily components and
subsystems already employed in the work machine.
2.1 What is Regenerative Brake?
A regenerative brake is a mechanism that reduces vehicle speed by converting some of
its kinetic energy into another useful form of energy. This captured energy is then stored
for future use or fed back into a power system for use by other vehicles.
For example, electrical regenerative brakes in electric railway vehicles feed the generated
electricity back into the supply system. In battery electric and hybrid electric vehicles, the
energy is stored in a battery or bank of capacitors for later use. Other forms of energy
storage which may be used include compressed air and flywheels.
Regenerative braking should not be confused with dynamic braking, which dissipates the
electrical energy as heat and thus is less energy efficient.
2.2 The Motor as a Generator.
Regenerative braking utilizes the fact that an electric motor can also act as a generator.
The vehicle's electric traction motor is operated as a generator during braking and its

4. 4
output is supplied to an electrical load. It is the transfer of energy to the load which
provides the braking effect.
An early example of this system was the Energy Regeneration Brake, developed in 1967
for the Amitron. This was a completely battery powered urban concept car whose
batteries were recharged by regenerative braking, thus increasing the range of the
automobile.
2.3 Kinetic Energy Recovery Systems
Kinetic Energy Recovery Systems (KERS) are currently under development both for F1
motor sport and road vehicles. The concept of transferring the vehicle’s kinetic energy
using Flywheel energy storage was postulated by physicist Richard Feynman in the 1950s
and is exemplified in complex high end systems such as the Zytek, Flybrid,
Torotrak,
and
Xtrac used in F1 and simple, easily manufactured and integrated differential based
systems such as the Cambridge Passenger/Commercial Vehicle Kinetic Energy Recovery
System (CPC-KERS)
Xtrac & Flybrid are both licensees of Torotrak's technologies, which employ a small and
sophisticated ancillary gearbox incorporating a continuously variable transmission
(CVT). The CPC-KERS is similar as it also forms part of the driveline assembly.
However, the whole mechanism including the flywheel sits entirely in the vehicle’s hub
(looking like a drum brake). In the CPC-KERS, a differential replaces the CVT and
transfers torque between the flywheel, drive wheel and road wheel.
2.4 Regenerative Braking…. The Stop & Go money saver.
For decades we have always heard that stop n' go traffic was not only bad for our
pocketbooks, but as you'll see on Mean Green Machines, it's also hard on the
environment due to the extended driving, excess idling, and wasted engine output. Did
you know that about 30 percent of your cars' engine output is lost through braking in
heavy traffic, and the deeper in the city you travel, chances are the worse your percentage
is.
Not to mention the higher the road rage in your area... the more people are probably
stomping on the gas peddle, racing up to your bumper, and then hard braking to a stop.
What if we told you that you could actually save money and a little bit of wear and tear
on the environment through such stop n' go traveling? Even those road rage drivers may
do the environment a bit of a favor. Well you can, and it is through the nifty little
technology called regenerative braking.

5. 5
While not exactly much of a complicated technological advancement, regenerative
braking offers a huge advantage, but it only works with hybrid-electric vehicles.
Conventional combustion engines can only do one thing and that is convert fuel to energy
and heat to move forward.
This means that every time you apply the brakes to stop that forward movement, you are
wasting energy. However, in the case of the hybrid/electric, you would be creating
energy. How it works is very similar to an electric generator.
Every time an electric car moves forward it is using its stored energy. This is its torque
phase and it generally causes your vehicle to lose stored energy in order to create the
energy necessary to move you forward.
However, at the moment you lift up from the accelerator to slow down, the torque phase
shuts down and the electric engine switches over to an electric generator and uses the
"free" momentum of the vehicle to create new energy stores for the battery.
This translates to a vehicle that can generate the energy necessary to leave a stop light
while it is coming to a stop in front of it. Ultimately any car that can produce energy
while in motion is bringing us closer to a self sustaining energy source.
2.5 Regenerative Braking in D.C. System.
Electric stock may recuperate energy during braking by using traction motors as
generators. In DC supply systems (1,5 and 3 kV) high recovery rates are only achievable
under favourable conditions.

6. 6
CHAPTER – 3
METHODOLOGY/EXPERIMENTAL SETUP
3.1 Component used.
1. Electromagnetic Clutch
2. Dynamo
3. DC Gear Motor
4. Transformer
5. Bridge Rectifier
6. Brake Paddle
7. Bearing
8. Wheel
9. Chain assembly
10. Wooden Frame
Many more as per requirement….
3.2 About our project.
In this project we are using our vehicle momentum force into electric energy at the time
of applying braking system.
We are using simple wheel in our project and fixed on wooden frame with help of
bearing.
We fix one electromagnetic clutch on the side of wheel shaft and one gear on other side
of shaft as shown below diagram.
Now we fix one dynamo attach with electromagnetic clutch as shown below.
On the other side of wheel we attach one dc gear motor with chain assambly. We use dc
gear motor as engine in our model.
We control dc motor with simple sliding two way switch (sliding switch can stop and
play two device at the same tine) as shown below.

7. 7
3.3 Electromagnetic Clutch.
Electromagnetic clutches operate electrically, but transmit torque mechanically. This is
why they used to be referred to as electro-mechanical clutches. Over the years EMC
became known as electromagnetic versus electro mechanical, referring more about their
actuation method versus physical operation. Since the clutches started becoming popular
over sixty years ago, the variety of applications and clutch designs has increased
dramatically, but the basic operation remains the same.
Single-face clutches make up approximately 90% of all electromagnetic clutch sales. This
article mainly deals with these types of clutches. Alternative clutch designs are
mentioned at the end of this article.
3.4 How Electromagnetic Clutch Works?
Figure- 3.1 Electromagnetic Clutch when power is off.
Electromagnetic clutch (EMC)– When we provide power to EMC, it perform as a magnet
and attract iron gear as shown in below picture.

8. 8
Figure- 3.2 Electromagnetic Clutch when power is on.
As we see above gear is fixed with iron dice, when we provide power supply to EMC it
attract iron dice when dick attach with electromagnetic it transform shaft rotation to the
attached device.
3.5 Construction
A horseshoe magnet (A-1) has a north and south pole. If a piece of carbon steel contacts
both poles, a magnetic circuit is created. In an electromagnetic cultch, the north and south
pole is created by a coil shell and a wound coil. In a clutch, (B1) when powers applied, a
magnetic field is created in the coil (A2 blue). This field (flux) overcomes an air gap
between the clutch rotor (A2 yellow) and the armature (A2 red). This magnetic attraction,
pulls the armature in contact with the rotor face. The frictional contact, which is being
controlled by the strength of the magnetic field, is what causes the rotational motion to
start. The torque comes from the magnetic attraction, of the coil and the friction between
the steel of the armature and the steel of the clutch rotor. For many industrial clutches,
friction material is used between the poles. The material is mainly used to help decrease
the wear rate, but different types of material can also be used to change the coefficient of
friction (torque for special applications). For example, if the clutch is required to have an
extended time to speed or slip time, a low coefficient friction material can be used and if
a clutch is required to have a slightly higher torque (mostly for low rpm applications), a
high coefficient friction material can be used.

9. 9
Figure-3.3 Construction of electromagnetic clutch.
In a clutch, the electromagnetic lines of flux have to pass into the rotor, and in turn,
attract and pull the armature in contact with it to complete clutch engagement. Most
industrial clutches use what is called a single flux, two pole design (A-2). Mobile
clutches of other specialty electromagnetic clutches can use a double or triple flux rotor
(A-4). The double or trip flux refers to the number of north/south flux paths (A-6), in the
rotor and armature. These slots (banana slots) (A-7) create an air gap which causes the
flux path to take the path of least resistance when the faces are engaged. This means that,
if the armature is designed properly and has similar banana slots, what occurs is a leaping
of the flux path, which goes north south, north south (A-6). By having more points of
contact, the torque can be greatly increased. In theory, if there were 2 sets of poles at the
same diameter, the torque would double in a clutch. Obviously, that is not possible to do,
so the points of contact have to be at a smaller inner diameter. Also, there are magnetic
flux losses because of the bridges between the banana slots. But by using a double flux
design, a 30%-50% increase in torque, can be achieved, and by using a triple flux design,
a 40%-90% in torque can be achieved. This is important in applications where size and
weight are critical, such as automotive requirements.

10. 10
3.6 OTHER TYPES OF ELECTROMAGNETIC CLUTCHES
3.6.1 Multiple Disk Clutch
Figure- 3.4 Multiple Disk Clutch.
Introduction - Multiple Disk clutches are used to deliver extremely high torque in a
relatively small space. These clutches can be used dry or wet (oil bath). Running the
clutches in an oil bath also greatly increases the heat dissipation capability, which makes
them ideally suited for multiple speed gear boxes and machine tool applications.
How it works - Multiple disk clutches operate via an electrical actuation but transmit
torque mechanically. When voltage /current is applied to the clutch coil, the coil becomes
an electromagnet and produces magnetic lines of flux. These lines of flux are transferred
through the small air gap between the field and the rotor. The rotor portion of the clutch
becomes magnetized and sets up a magnetic loop, which attracts both the armature and
friction disks. The attraction of the armature compresses (squeezes) the friction disks,
transferring the torque from the in inner driver to the out disks. The output disks are
connected to a gear, coupling, or pulley via drive cup. The clutch slips until the input and
output RPMs are matched. This happens relatively quickly typically (.2 - 2 sec).
When the current/voltages are removed from the clutch, the armature is free to turn with
the shaft. Springs hold the friction disk away from each other, so there is no contact when
the clutch is not engaged, creating a minimal amount of drag.

11. 11
3.6.2 Electromagnetic Tooth Clutch
Figure- 3.5 Electromagnetic tooth clutch
Introduction - Of all the electromagnetic clutches, the tooth clutches provide the greatest
amount of torque in the smallest overall size. Because torque is transmitted without any
slippage, clutches are idea for multi stage machines where timing is critical such as multi
stage printing presses. Sometimes, exact timing needs to be kept, so tooth clutches can be
made with a single position option which means that they will only engage at a specific
degree mark. They can be used in dry or wet (oil bath) applications, so they are very well
suited for gear box type drives.
They should not be used in high speed applications or applications that have engagement
speeds over 50 RPM otherwise damage to the clutch teeth would occur when trying to
engage the clutch.
How it Works – Electromagnetic Tooth clutches operate via an electric actuation but
transmit torque mechanically. When voltage/current is applied to the clutch coil, the coil
becomes an electromagnet and produces magnetic lines of flux. This flux is then
transferred through the small gap between the field and the rotor. The rotor portion of the
clutch becomes magnetized and sets up a magnetic loop, which attracts the armature teeth
to the rotor teeth. In most instances, the rotor is consistently rotating with the input
(driver). As soon as the clutch armature and rotor are engaged, lock up is 100%.
When current/voltage is removed from the clutch field, the armature is free to turn with
the shaft. Springs hold the armature away from the rotor surface when power is released,
creating a small air gap and providing complete disengagement from input to output.

12. 12
3.6.3 Electromagnetic Particle Clutch
Figure- 3.6 Electromagnetic particle clutch
Introduction – Magnetic particle clutches are unique in their design, from other electro-
mechanical clutches because of the wide operating torque range available. Like a
standard, single face clutch, torque to voltage is almost linear. However, in a magnetic
particle clutch torque can be controlled very accurately. This makes these units ideally
suited for tension control applications, such as wire winding, foil, film, and tape tension
control. Because of their fast response, they can also be used in high cycle application,
such as card readers, sorting machines, and labeling equipment.
How it Works – Magnetic particles (very similar to iron filings) are located in the powder
cavity. Without any voltage/current they sit in the cavity. However, when voltage/current
is applied to the coil, the magnetic flux that is created tries to bind the particles together,
almost like a magnetic particle slush. As the voltage/current is increased, the magnetic
field builds, strengthening the binding of the particles. The clutch rotor passes through
the bound particles, causing drag between the input and the output during rotation.
Depending upon the output torque requirement, the output and input may lock at 100%
transfer.
When voltage/current is removed from the clutch, the input is free to turn with the shaft.
Since the magnetic particle is in the cavity, all magnetic particle units have some type of
minimum drag associated with them.

13. 13
3.7 Dynamo
A dynamo, originally another name for an electrical generator, now means a generator
that produces direct current with the use of a commutator. Dynamos were the first
electrical generators capable of delivering power for industry, and the foundation upon
which many other later electric-power conversion devices were based, including the
electric motor, the alternating-current alternator, and the rotary converter. They are rarely
used for power generation now because of the dominance of alternating current, the
disadvantages of the commutator, and the ease of converting alternating to direct current
using solid state methods.
The word still has some regional usage as a replacement for the word generator. A small
electrical generator built into the hub of a bicycle wheel to power lights is called a Hub
dynamo.
Figure- 3.7 Dynamo
3.8 D.C. Motor
The DC motor has a rotating armature in the form of an electromagnet. A rotary switch
called a Commutator reverses the direction of the electric current twice every cycle, to
flow through the armature so that the poles of the electromagnet push and pull against the
permanent magnets on the outside of the motor. As the poles of the armature
electromagnet pass the poles of the permanent magnets, the Commutator reverses the
polarity of the armature electromagnet. During that instant of switching polarity, inertia
keeps the classical motor going in the proper direction. (See the diagrams below.)
A simple DC electric motor. When the coil is powered, a magnetic field is generated
around the armature. The left side of the armature is pushed away from the left magnet
and drawn toward the right, causing rotation.

14. 14
Figure- 3.8 D.C. Motor
When the armature becomes horizontally aligned, the Commutator reverses the direction
of current through the coil, reversing the magnetic field. The process then repeats.
3.9 Transformer
A transformer is an electrical device that transfers energy from one circuit to another by
magnetic coupling with no moving parts. A transformer comprises two or more coupled
windings, or a single tapped winding and, in most cases, a magnetic core to concentrate
magnetic flux. A changing current in one winding creates a time-varying magnetic flux in
the core, which induces a voltage in the other windings.
Figure- 3.9 Step-down Transformer

15. 15
3.10 Brake Paddle
The brake paddle is also known as paddle switch. It is used to turn off the power supply
to the DC motor.
Figure- 3.10 Brake Paddle
3.11 Bridge Rectifier
The bridge rectifier is used to convert the AC current into DC current.
Figure- 3.11 Bridge Rectifier

16. 16
CHAPTER – 4
WORKING
The working of regenerative braking system has few steps as shown in
below:
Step-1
We are using simple wheel in our project and fixed on wooden frame with help of
bearing.
Figure- 4.1 Wheel fixed on wooden frame.
Step-2
We fix one electromagnetic clutch on the side of wheel shaft and one gear on other side
of shaft as shown below diagram.

17. 17
Figure- 4.2 Electromagnetic clutch fixed on wheel shaft.
Step-3
Now we fix one dynamo attach with electromagnetic clutch as shown below.
Figure- 4.3 Dynamo attach with electromagnetic clutch.
Step-4
On the other side of wheel we attach one dc gear motor with chain assembly. We use dc
gear motor as engine in our model.
Figure- 4.4 DC gear motor with chain assembly.

18. 18
Step-5
We control dc motor with simple sliding two way switch (sliding switch can stop and
play two device at the same tine) as shown below.
Figure- 4.5 DC motor with simple sliding two way switch
Step-6
DC motor drive wheel with the help of gear assembly
Figure- 4.6 DC motor drive the wheel

19. 19
Step-7
Power Generation at the time of Braking
When we sliding switch off to motor supply then switch on electromagnetic clutch power
supply. Electromagnetic clutch engages with wheel shaft and transfer wheel rotation in
the dynamo for stopping wheel rotation. When dynamo rotates it applied brake to the
wheel shaft and produce energy, which is storing in battery as shown below.
4.1 Working Block Diagram.
Figure- 4.7 Block Diagram

20. 20
CHAPTER – 5
DISCUSSION
The present invention provides a regenerative braking system for a work machine.
The invention, in one form thereof, is directed to a regenerative braking system for a
work machine. The work machine has a drive system for driving the work machine, and a
hydraulic system for operating the work machine, the hydraulic system powered by a
main hydraulic pump. The regenerative braking system includes a ground driven
hydraulic pump coupled to the drive system, the ground driven hydraulic pump being
configured to absorb shaft power from the drive system by converting the shaft power
into a hydraulic flow, and the hydraulic pump also being configured to provide shaft
power to the drive system by converting hydraulic flow into shaft power. The
regenerative braking system also includes a hydraulic circuit fluidly coupled to the
ground driven hydraulic pump.
The hydraulic circuit is configured to selectively receive and store energy from the drive
system via the ground driven hydraulic pump; transmit the energy back to the drive
system via the ground driven hydraulic pump; and direct hydraulic flow from the ground
driven hydraulic pump to the hydraulic system when an output of the main hydraulic
pump drops below a desired level.
The invention, in another form thereof, is directed to a work machine. The work machine
includes an engine; a drive system powered by the engine for driving the work machine;
a main hydraulic pump powered by the engine; a hydraulic system for operating the work
machine, wherein the hydraulic system powered by the main hydraulic pump; and a
regenerative braking system. The regenerative braking system includes a ground driven
hydraulic pump coupled to the drive system, the ground driven hydraulic pump being
configured to absorb shaft power from the drive system by converting the shaft power
into a hydraulic flow, and the hydraulic pump also being configured to provide shaft
power to the drive system by converting hydraulic flow into shaft power. The
regenerative braking system also includes a hydraulic circuit fluidly coupled to the
ground driven hydraulic pump. The hydraulic circuit is configured to selectively receive
and store energy from the drive system via the ground driven hydraulic pump; transmit
the energy back to the drive system via the ground driven hydraulic pump; and direct
hydraulic flow from the ground driven hydraulic pump to the hydraulic system when an
output of the main hydraulic pump drops below a desired level.

21. 21
CHAPTER – 6
CONCLUSION AND FUTURE WORK
We find out after working 18-20 volt DC by the dynamo at 730 rpm of dynamo shaft.
We found brake efficiency increased.
And also found reduce emission (CO2 emission)
As well as reduce fuel consumption
Following different companies are use this system and details mention as
6.1 Which green cars use regenerative braking?
Any current hybrid car will make use of regenerative braking. Some of the earliest
examples of hybrids using the system include the Toyota Prius, the Honda Civic hybrid,
the Lexus RX 400h and the GS 450h.
Regenerative braking is also crucial to the development of cars using compressed air.
Compressed air cars have a similar range to electric vehicles with zero emissions.
Compressed air engines reduce the cost of vehicle production by around 20 per cent as
there is no need for a fuel tank, cooling system, spark plugs or silencers.
In addition, regenerative braking systems will soon be vital in the sport of motor racing.
All cars must become hybrid by 2013 according to regulations by the FIA with
regenerative braking used alongside a kinetic energy recovery system.
6.2 Use in motor sport
F1 teams began testing Kinetic Energy Recovery Systems, or KERS, in January 2009.
Teams have said they must respond in a responsible way to the world's environmental
challenges.
The FIA allowed the use of 60 kW KERS in the regulations for the 2009 Formula One
season.

22. 22
6.2.1 Motorcycles
KTM racing boss Harald Bartol has revealed that the factory raced with a secret Kinetic Energy
Recovery System (KERS) fitted to Tommy Koyama's motorcycle during the season-ending 125cc
Valencian Grand Prix.
6.2.2 Autopart makers
Bosch Motorsport Service (part of the subsidiary Bosch Engineering GmbH) is
developing a KERS for use in motor racing. Hybrid systems by Bosch Motorsport
comprise an electricity storage system (a lithium-ion battery with scalable capacity or a
flywheel), the electric motor (weigh between four and eight kilograms with a maximum
power level of 60 kW) and the KERS controller, containing the power electronic, battery
management, and management system for hybrid and engine functions . The Bosch
Group offers a range of electric hybrid systems for commercial and light-duty
applications.
6.2.3 Carmakers
BMW and Honda are testing it. At the 2008 1000 km of Silverstone, Peugeot Sport
unveiled the Peugeot 908 HY, a hybrid electric variant of the diesel 908, with KERS.
Peugeot plans to campaign the car in the 2009 Le Mans Series season, although it will not
be capable of scoring championship points.
Vodafone McLaren Mercedes began testing of their KERS in September 2008 at the
Jerez test track in preparation for the 2009 F1 season, although at that time it was not yet
known if they would be operating an electrical or mechanical system. In November 2008
it was announced that Freescale Semiconductor would collaborate with McLaren
Electronic Systems to further develop its KERS for McLaren's Formula One car from
2010 onwards. Both parties believed this collaboration would improve McLaren's KERS
system and help the system filter down to road car technology .
Toyota has used a super capacitor for regeneration on Supra HV-R hybrid race car that
won the 24 Hours of Tokachi race in July 2007.
6.3 Comparison of dynamic and regenerative brakes.
Dynamic brakes ("rheostatic brakes" in the UK), unlike regenerative brakes, dissipate the
electric energy as heat by passing the current through large banks of variable resistors.
Vehicles that use dynamic brakes include forklifts, Diesel-electric locomotives and

23. 23
streetcars. If designed appropriately, this heat can be used to warm the vehicle interior. If
dissipated externally, large radiator-like cowls are employed to house the resistor banks.
The main disadvantage of regenerative brakes when compared with dynamic brakes is the
need to closely match the generated current with the supply characteristics. With DC
supplies, this requires that the voltage be closely controlled. Only with the development
of power electronics has this been possible with AC supplies, where the supply frequency
must also be matched (this mainly applies to locomotives where an AC supply is rectified
for DC motors).
A small number of mountain railways have used 3-phase power supplies and 3-phase
induction motors. This results in a near constant speed for all trains as the motors rotate
with the supply frequency both when motoring and braking

24. 24
. CHAPTER-7
COST OF PROJECT & ADVANTAGES
Cost estimate (Table. No. 7.1)
S.no. Components Costs in (Rs.)
1. DC motor 950
2. Dynamo 290
3. Proximity sensor (kit) 190
4. Bridge rectifier 175
5. Electromagnetic clutch 225
6. Wheel 480
7. Wooden frame & chain 750
Total cost = Rs.3060
7.2 Advantage
Regenerative brake cooperative control balances the brake force of the regenerative and
hydraulic brakes to minimize the amount of kinetic energy lost to heat and friction. It
recovers the energy by converting it into electrical energy. To convert kinetic energy to
electrical energy the system uses MG2 as a generator. The drive axle and MG2 are joined
mechanically. When the drive wheels rotate MG2 which tends to resist the rotation of the
wheels, providing both electrical energy and the brake force needed to slow the vehicle.

25. 25
The greater the battery charging amperage, the greater the resistance. The various uses of
regenerative brakes are recharging a battery pack that power vehicle, taking accessory
loads such as lights, taking accessory loads such as radio and stereo, giving power to
pumps, conditioners and fans and in railways.
7.3 Limitations
Traditional friction-based braking is used in conjunction with mechanical regenerative
braking for the following reasons:
 The regenerative braking effect drops off at lower speeds; therefore the friction
brake is still required in order to bring the vehicle to a complete halt. Physical
locking of the rotor is also required to prevent vehicles from rolling down hills.
 The friction brake is a necessary back-up in the event of failure of the
regenerative brake.
 Most road vehicles with regenerative braking only have power on some wheels
(as in a two-wheel drive car) and regenerative braking power only applies to such
wheels because they are the only wheels linked to the drive motor, so in order to
provide controlled braking under difficult conditions (such as in wet roads)
friction based braking is necessary on the other wheels.
 The amount of electrical energy capable of dissipation is limited by either the
capacity of the supply system to absorb this energy or on the state of charge of the
battery or capacitors. Regenerative braking can only occur if no other electrical
component on the same supply system is drawing power and only if the battery or
capacitors are not fully charged. For this reason, it is normal to also incorporate
dynamic braking to absorb the excess energy.
Under emergency braking it is desirable that the braking force exerted be the maximum
allowed by the friction between the wheels and the surface without
 Slipping, over the entire speed range from the vehicle's maximum speed down to
zero. The maximum force available for acceleration is typically much less than
this except in the case of extreme high-performance vehicles. Therefore, the
power required to be dissipated by the braking system under emergency braking
conditions may be many times the maximum power which is delivered under
acceleration. Traction motors sized to handle the drive power may not be able to
cope with the extra load and the battery may not be able to accept charge at a
sufficiently high rate. Friction braking is required to dissipate the surplus energy
in order to allow an acceptable emergency braking performance.

26. 26
CHAPTER – 8
REFERENCES
1. Grahame, James "1968: AMC's Amazing Amitron Electric Car" Retro Thing:
Vintage Gadgets and Technology 22 September 2008, retrieved on 13 April 2009.
2. "Next: the Voltswagon?" Time Magazine, 22 December 1967, retrieved on 13
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