DEPARTMENT OF MECH ENGG

CERTIFICATE

ACKNOWLEDGEMENT

CANDIDATES DECLARATION

INDEX1. ABSTRACT………………………………………………………………..052. PROJECT DESCRIPTION……………………………............................063. INTRODUCTION OF INDUCTION BRAKING………………………084. PROPOSED METHODOLOGY………………………………………...16

Linear eddy current brake…………..…………………………….17 Explanation for use of eddy current brake design……………….18 Overview of eddy current generation……………………………..19 Eddy current generation diagram………………………………...21 Determining force produced by eddy currents…………………...22 Component orientation…………………………………………….23 Disc orientation……………………………………………………..24

5. EXPERIMENTAL SET UP…………………………………………. 25-316. FORCE ANALYSIS…………………………………………………...32-37

Structural Analysis……………………………………………......33 Stress due to imbalance……………………………………………34 Stress due to eddy current………………………………………...35

7. MATERIAL SELECTION………………………………………………………..38-40

8. PRACTICAL APPLICATION……………………………………………………..41-47

9. THEORITICAL TESTING………………………………………………………........48-52

10.OPERATIONAL APPLICATION……………………………………………………..53-55

11.SAFTEY IMPROVEMENT………………………………………………………56

12.COST AND BENEFITS…………………………………………………………… ...57

13.ADVANTAGES………………………………………………………...5814.CONCLUSION…………………………………………………………5915.COST ANALYSIS………………………………………………………6016.RESULT…………………………………………………………………6117.REFRENCES……………………………………………………………62

ABSTRACT

An Induction brake, like a conventional friction brake, is responsible for slowing an object, such as a train or a roller coaster. However, unlike electro-mechanical brakes, which apply mechanical pressure on two separate objects, eddy current brakes slow an object by creating eddy currents through electromagnetic induction which create resistance, and in turn either heat or electricity.

Induction brakes are similar to electrical motors; non-ferromagnetic metal discs (rotors) are connected to a rotating coil, and a magnetic field between the rotor and the coil creates a resistance used to generate electricity or heat. When electromagnets are used, control of the braking action is made possible by varying the strength of the magnetic field. A braking force is possible when electric current is passed through the electromagnets. The movement of the metal through the magnetic field of the electromagnets creates eddy currents in the discs. These eddy currents generate an opposing magnetic field (Lenz's law), which then resists the rotation of the discs, providing braking force. The net result is to convert the motion of the rotors into heat in the rotors.

Project Discription

To demonstrate the production of torque, we've essentially taken the driveshaft and built a test rig around it.  By attaching a conductive disc to the driveshaft and setting up electromagnets around it, we can create a braking force (assuming the disc is moving fast) to decelerate the driveshaft.  If we can prove that the required torque is achievable via eddy-current-braking, then the electro-magnets can be installed.

WHAT IS BRAKING ?

A brake is a device used for slowing or stopping the motion of a

machine or vehicle, and to keep it from starting to move again. The

kinetic energy lost by the moving part is usually translated to heat by

friction.

Kinetic energy increases with the square of the velocity

(E = ½m·v2 relationship). This means that if the speed of a vehicle

doubles, it has four times as much energy. The brakes must therefore

dissipate four times as much energy to stop it and consequently the

braking distance is four times as long.

• The efficient way to reduce the waste of energy in braking the

conventional ways is to employ electric braking technology.

INTRODUCTION

OF

INDUCTION BRAKING

WHAT IS INDUCTION BRAKING?

Induction brakes are used in electrically driven utilities and machines

in industries and mainly in electric automotives such as electric locos.

This was designed as an alternative to the conventional braking

system of applying friction over the wheels to slow them .Here the

kinetic energy is converted back into electrical form which otherwise

is wasted while braking the system. This is aided by the ability of

certain motors, to run as generators when the torque gets reversed.

The generated energy may be either stored in a battery or sent back to

the grid as in electric locomotives .

Induction brake

Electromagnetic brakes are similar to electrical motors; non-ferromagnetic metal discs (rotors) are connected to a rotating coil, and a magnetic field between the rotor and the coil creates a resistance used to generate electricity or heat. When electromagnets are used, control of the braking action is made possible by varying the strength of the magnetic field. A braking force is possible when electric current is passed through the electromagnets. The movement of the metal through the magnetic field of the electromagnets creates eddy currents in the discs. These eddy currents generate an opposing magnetic field, which then resists the rotation of the discs, providing braking force. The net result is to convert the motion of the rotors into heat in the rotors.

Japanese Shinkansen trains had employed circular eddy current brake system on trailer cars since 100 Series Shinkansen. However, N700 Series Shinkansen abandoned eddy current brakes in favour of regenerative brakes since 14 of the 16 cars in the trainset used electric motors.

TYPES OF INDUCTION BRAKING:

Regenerative Braking

Rheostatic/Dynamic Braking

Electromagnetic/Eddy current Braking

Regenerative Braking

A regenerative brake is an energy recovery mechanism which slows a

vehicle or object down by converting its kinetic energy into another

form, which can be either used immediately or stored until needed.

This contrasts with conventional braking systems, where the excess

kinetic energy is converted to heat by friction in the brake linings and

therefore wasted.

The most common form of regenerative brake involves using an

electric motor as an electric generator. In electric railways the

generated electricity is fed back into the supply system, whereas in

battery electric and hybrid electric vehicles, the energy is stored in a

battery or bank of capacitors for later use. Energy may also be stored

mechanically via pneumatics, hydraulics or the kinetic energy of a

rotating flywheel

• Regenerative brakes are discovered in 1832 .

• In the regenerative system, the kinetic energy is converted back

into electrical form which otherwise is wasted while braking the

system. This is done by the ability of certain motors, to run as

generators when the torque gets reversed.

• The generated energy may be either stored in a battery or sent

back to the grid as in electric locomotives.

• Regenerative brakes take energy normally wasted during braking

and turn it into usable energy.

WORKING OF REGENERATIVE BRAKING

When a vehicle is approaching a stop light, it does not create

friction and useless heat in order to slow down.

Instead it reverses its electric motor turning it into an electric

generator, creating electricity which is fed back into a battery

and stored for further use.

In fact any time a hybrid-electric vehicle slows down

( lifting the accelerator or application of the "brake“) causes the

system to use the vehicle's momentum to generate electricity.

DYNAMIC BRAKING

During braking, the motor fields are connected across either the main traction generator (diesel-electric loco) or the supply (electric locomotive) and the motor armatures are connected across either the brake grids or supply line. The rolling locomotive wheels turn the motor armatures, and if the motor fields are now excited, the motors will act as generators.

During dynamic braking the traction motors which are now acting as generators are connected to the braking grids (Large resistors) which put a large load on the electrical circuit. When a generator circuit is loaded down with resistance it causes the generators to slow their rotation. By varying the amount of excitation in the traction motor fields and the amount of resistance imposed on the circuit by the resistor grids, the traction motors can be slowed down to a virtual stop (approximately 3-5 MPH).

The electrical energy produced by the motors is dissipated as heat by a bank of onboard resistors. Large cooling fans are necessary to protect the resistors from damage. Modern systems have thermal monitoring, so if the temperature of the bank becomes excessive, it will be switched off, and the braking will revert to air only.

Dynamic braking alone is insufficient to stop a locomotive, as its braking effect rapidly diminishes below about 10 to 12 miles per hour (16 to 19 km/h). Therefore it is always used in conjunction with the regular air brake. This combined system is called blended braking. Li-ion batteries have also been used to store energy for use in bringing trains to a complete halt.

ELECTROMAGNETIC BRAKING

An eddy current brake, like a conventional friction brake, is responsible for slowing an object, such as a train or a roller coaster. However, unlike electro-mechanical brakes, which apply mechanical pressure on two separate objects, eddy current brakes slow an object by creating eddy currents through electromagnetic induction which create resistance, and in turn either heat or electricity.

WORKING

• As the metal disc rotates inside the magnetic field, electric currents,

called eddy currents are induced inside it. Those currents then

generate a magnetic field in opposition to the original field thus

creating a force which acts to decelerate the rotating disc.

• Heat is created in the disc as a result of the electrical resistance of

the disc material and the current induced in it; this heat represents

the kinetic energy being dissipated and is analogous to the heat

generated by a conventional friction brake.

• The electromagnet allows control of the braking action by varying

the strength of the magnetic field to produce a braking force,

• Because the induced current is proportional to the speed of the disc

the braking torque decreases as the disc decelerates resulting in a

smooth stop.

• Regenerative braking is not used with brakes of this type since the

induced current is dissipated as heat and is not practical to recover.

Basic Function Of Induction Brake

1. Electromagnets produce magnetic field from supplied current2. Change of magnetic flux (with time) induces eddy currents in

conductor (disc)3. Eddy Currents produce another magnetic field opposing first

field4. Opposing magnetic fields create force that reduces velocity

PROPOSED

METHODOLOGY

Linear Eddy Current Brake

The principle of the linear eddy current brake has been described by the French physicist Foucault, hence in French the eddy current brake is called the "frein à courants de Foucault".

The linear eddy current brake consists of a magnetic yoke with electrical coils positioned along the rail, which are being magnetized alternating as south and north magnetic poles. This magnet does not touch the rail, as with the magnetic brake, but is held at a constant small distance from the rail (approximately seven millimeters). It does not move along the rail, exerting only a vertical pull on the rail.

When the magnet is moved along the rail, it generates a non-stationary magnetic field in the head of the rail, which then generates electrical tension (Faraday's induction law), and causes eddy currents. These disturb the magnetic field in such a way that the magnetic force

is diverted to the opposite of the direction of the movement, thus creating a horizontal force component, which works against the movement of the magnet.

The braking energy of the vehicle is converted in eddy current losses which lead to a warming of the rail. (The regular magnetic brake, in wide use in railways, exerts its braking force by friction with the rail, which also creates heat.)

The eddy current brake does not have any mechanical contact with the rail, and thus no wear, and creates no noise or odor. The eddy current brake is unusable at low speeds, but can be used at high speeds both for emergency braking and for regular braking.

The first train in commercial circulation to use such a braking is the ICE 3.

Modern roller coasters use this type of braking, but utilize permanent magnets instead of electromagnets, and require no electricity. However, their braking strength cannot be adjusted as easily as with an electromagnet.

Explanation for use of Eddy Current Brake Design

Taking into consideration recommended use of the Eddy Current Brake System, we chose the Eddy Current Brake design because it is most capable with all of achieving all requirements and working within all constraints defined in this project. The Eddy Current Brake System (ECBS) will permit a frictionless, non-contact, reset-able solution to generator disconnect activation. With choosing the ECBS we may also use some of the constraints to our advantage as opposed to the constraints acting as a limiting factor or hindrance. For example, due to the ECBS not needing any frictional force, we will use the oil mist environment as a cooling agent to the heat generated by the Eddy Currents and will not have to worry about the oil causing slip.

By using a frictionless braking system, such as the ECBS we reduce the mechanical dependence of this system, however, that does not lead to neglecting other mechanical properties. Stresses need to be considered to assure we have selected a suitable material that will withstand the braking forces when activated as well as the constant rotation of the disk when not in use.

The ECBS will work within all given parameters and limitations. Finding the material properties of the ECBS and strengths of electromagnets will determine its efficiency. We will alter properties as needed and present a solution that will work. The functioning final product will act as a secondary prototype which may exceed the limitations set by Honeywell

but will function to the needs of Honeywell. In addition to coming up with a secondary prototype we will optimize our design to work within all limitations but may not function to the requirements of Honeywell. This design will work to the best of its ability but may fall short in accomplishing the final goal of 160 inch-pounds of torque. The final design will ideally produce the 160 inch-pounds needed and work within all limitations set by Honeywell. This report will go into detail on the analysis of an Eddy Current Brake System in latter portions of this section.

The ECBS setup will contain a total of eight electromagnets with a strength presented in the Structural Analysis section of this report, an aluminum conducting disc with properties given in the Materials Selection portion of this report, and any other components needed for the test rig assembly. Figure depicts the setup we will use for our Eddy Current Brake System.

Figure : Eddy Current Brake System

We feel that all of our design concepts will perform its duty and serving as a reasonable replacement for the current shear neck design. However, given certain constraints and limitations we determined that the ECBS is the best option for this particular application given all of the requirements. In the section entitled “Dismissal of Alternative Solutions” we rule out the other concepts for their respective reasons. We explain why we did not choose them but also why they would serve as a viable option for disconnect activation.

Overview of Eddy Current Generation

Eddy Currents are in induced current that exist in a solid. A changing magnetic flux over an area of the solid will produce an Eddy Current which will create a magnetic field opposing the field producing the Eddy Currents. The opposition of this generated magnetic field is dependant on the changing area. As the area of flux increases the Eddy Current generation is in a “negative” direction. With a decreasing area exposed to the flux the generated Eddy Currents will act in the opposite, “positive”

Eddy Current Generation Diagram

The figure shows one plate at two instances in time. The first instant models the plate just entering the magnetic field directed into the page. The swirl indicated on the plate illustrates the direction of the Eddy Current. The Eddy Current in position one has a “negative” direction or counter clockwise direction. The second position shows the Eddy current swirl going in the “positive” direction, or clockwise, as the plate has a decreasing area passing through the flux. Essentially, at the middle of the field there is no Eddy Current generation and also acts as the point in which the Eddy Current generation changes direction.

The diagram also shows a force,Fb , which represents the force created by the Eddy Currents that are generated. The force created by the Eddy Currents will always oppose the direction of motion. The magnetic field generated by the Eddy Currents will oppose one another in position one of figure, and attract each other as the area is decreasing, thereby creating a force that always opposes the direction of the plate’s motion. The force produce by the Eddy Current generation is proportional to the conductivity of the material and the magnitude of the magnetic field, B.

Determining Force Produced by Eddy Currents

The analysis for determining the amount of force created by Eddy Currents with a known magnetic field proves extremely tedious. Writing a computer program to calculate the force produced by the eddy currents is not within the scope of this project and would far exceed our timeline. We purchased a software program called Faraday, which will calculate the force generated by the induced eddy current. Nearly all other modes of analysis require the known force created by eddy current generation. To approximate those forces we wrote a basic MATLAB program to simulate the eddy current force generated. The MATLAB program will be discussed in greater detail in the following sections.

.

Component Orientation

Electromagnet Orientation

We will use a total of four pairs of electromagnets per request .We will need to use four pairs or less in order to fall under the weight limitation of our design. The pairs will be oriented with the polarities aligning North to South and the disc spinning between the pairs. We will discuss in more detail the component design for the Electromagnets. We will build our own electromagnet coils using materials defined in this report, later in this section. By building our own electromagnets we may establish their polarity and when orienting them in the housing we will alternate the directions of polarity. Alternating the polarity will produce a greater force in our final product. In addition to opposite polarity it may not make a difference where we mount the electromagnets, so long as they are mounted very close and perpendicular to the disc and not too close to each other. We will optimize this property of our design with further testing and analysis. A study done by Caldwell, N.J and J.R.M. Taylor of the University of Edinburgh in Scotland on Oct 10, 2007, shown in Appendix D, proves that a change of polarity in electromagnets applied to eddy current brakes will produce a higher force than only one direction of polarity. We will likely mount the magnets depicted in figure 1 on page15, however upon testing we may conclude that having the magnets closer together may create the maximum torque. Further testing will either prove or disprove this concept.

Disc Orientation

The disc will have only one orientation. It will mount perpendicularly to the drive shaft and the electromagnets while mounted in the middle of the paired coils. One major concern comes in the form of how we will fasten the disk to the drive shaft. We will most likely pressure fit a collar around the drive shaft thereby attaching the disc by way of a pressure fit collar. If this is not feasible, we will conduct further review and brainstorming for a new way to fasten the disc to the drive shaft.

EXPERIMENTAL

SET UP

SET UP

Again, the overall goal is to produce a torque on the drive shaft (green) that will activate a disconnect system (not shown here).  A torque on the shaft is equivalent to a torque on the conductive disc since they are directly connected.  We’ve constructed a test apparatus (shown below) that consists of the drive-shaft, conductive disc, electromagnets, and other components necessary for operation and data collection.  The apparatus will be used to show that the braking torque is achievable with the geometry dictated by Honeywell Aerospace’s specific application.

Vision of Apparatus After Initiation of Assembly

Description of components

1. Battery : 12 V dc

2. DC motor : 300 Rpm

3. Metal Disc : Aluminium 7075

4. Electromagneta. Soft Iron Coreb. Copper wire

5. Multimeter

6. Brake Paddle and Accelerater paddle

Electromagnet Design

The electromagnets will be built and assembled by our team. Building our own electromagnets gives us the ability to generate the magnetic field needed. We will use standard coated copper wire coiled around a ferrous metal core. Coating the copper wire will prevent corrosion and increase the life of the electromagnets and maintain the efficiency of the overall braking system. The number of turns of copper around our ferrous material will determine the strength of the induced magnetic field. Upon further analysis with the Faraday computer program we will determine how many turns are needed per coil as well as the amperage needed to provide the needed magnetic field, which determines the force generated. Building our own to the needed specifications will also cut down on cost of the product as well as give Honeywell specifications to build their own, have outsourced, or purchase.

After researching electromagnet design we determined a ferrous material, such as 409 stainless steel or iron, ideal for a metal core for electromagnets. When constructing the electromagnet components, we will coat the copper wires and exposed core with a protective epoxy coating as to not leave the electromagnets exposed to the environment established earlier in this report. When mounting the electromagnets we will mount them in pairs. By pairing the electromagnets and aligning north-south polarity we will direct and concentrate the magnetic field to ensure a perpendicular magnetic field with maximum possible magnitude. The magnetic pairs will produce a similar magnetic field to the illustration in figure 3.

Figure 3: Magnetic field lines of Coil Pairs

shows that the magnetic field is concentrated and controllable between the coil pairs. In our design the disc will operate

between the two coils. This phenomenon will produce maximum magnitude and flux to the disc thereby generating

maximum force.

Conducting Disc Design

The design of the disc is fairly simple. We will use a highly conductive material that will also keep its shape and material properties over the lifetime of the generator. If the disc becomes warped, looses conductivity or fails in some other manner results in the overall failure of the ECBS. Assuring the material used to perform adequately is

detrimental to the success of the ECBS’s function as an activation system.

We will machine the disc from a 5.25 square inch aluminum alloy slab with a thickness of 0.1 inch to fit the design envelop requirements. The disc will be machined to a radius of 2.4 inches with an established tolerance of plus or minus five-hundredths of an inch. Our main focus is the selection of a suitable material.

.

FORCE ANALYSIS

STRUCTURAL ANALYSIS

Stress Analysis for Final Design

Stress Due to the Rotating Disc

The high rotation rate of the disc will cause enormous stresses within the disc. The rotation is by far the source contributing the largest amount of stress in the disc. According to Shigley’s Mechanical Engineering Design Eighth Edition by Richard G. Bundynas and J. Keith Nisbett the equations that quantify these stresses act in both the tangential and radial directions where tangential is defined as the direction tangent to the outer edge of the circle created by the silhouette of the disc, and radial is defined as the direction starting at the axis of rotation of the disc and moving outward through the plane of the disc. Both the tangential and radial stresses are functions of the interesting radius, r. The equations, listed on page 110 of the text book, are shown below.

st=ρw2 ( 3+ν8 )(ri

2+ro2+

ri2 r o

2

r 2−1+3 ν

3+νr 2)

sr=ρw2 ( 3+ν8 )(ri

2+ro2−

ri2 ro

2

r2−1+3 ν

3+ν−r2)

t = tangential stress

r = radial stress

ri = inner radius

ro = outer radius

= Poisson’s ratio

ρ = material density

ω = angular velocity [rad/s]

Stress Due to Imbalance

The customer provided a constraint for the imbalance of the disc. The disc should not exceed 0.005 oz*in. To complete a stress analysis on the disc due to this imbalance a definition for the term imbalance was decided. An imbalance of 0.005 oz*in would analytically equivalent to additional mass of disc material in the amount of 0.005 oz (requiring no additional volume), located in the disc a distance of 1 inch from the axis of rotation and symmetric across the thickness of the disc. A more generic definition with an imbalance of MR is depicted below.

Figure 4: Modeling of Imbalance Analysis

The magnitude of the stress caused by the imbalance was found to be very small and insignificant compared to the stress caused by the angular velocity of the disc.

Stress Due to Eddy Currents

The Forces that the eddy currents cause on the disc oppose the direction of motion the disc. In the image below the red arrows indicate the direction of rotation of the disc and the E vectors represent the corresponding eddy-current-forces on the differential ring element of the disc.

Figure :Differential Piece of Disc for Force Analysis

Heat Transfer

The eddy currents are, as their name indicates, electrical currents within the disc. The disc material acts as an electrical resistor. As current passes through an electrical resistance, electrical energy is converted to thermal energy. The eddy currents will cause the disc to heat up. Since it takes less than a second for the disconnect to activate, the current will only be flowing through the disc material for a

very short time. The assumption was made that the heating due to the eddy currents in this short amount of time would be negligible.

To verify the validity of this assumption, a heat transfer analysis was conducted on the disc. For heat transfer purposes the assumption was made that the rotating disc could be approximated as a static flat plate made of 6061 aluminum with a length of L = 2[(ro + ri)/2] and with an oil mist fluid passing by it at a velocity of v = minravg where min is the minimum angular velocity of the disc (minimum is worst case scenario because less heat can be removed by convection for smaller fluid velocities) and ravg is the average between the inner and outer radii of the disc.

Using the appropriate equations and the thermophysical properties of engine oil (to approximate oil mist environment) the Reynolds number and Nusselt number were calculated so that an average convection coefficient could be calculated. The heat rate transferred from the disc was then calculated. Subtracting this value from the heat rate transferred into the disc (electrical power) provides the net heat transferred into the disc. The final disc temperature can then be calculated based on a guess for the initial disc temperature. Several different initial temperatures were guessed and all verified our assumption that the increase in disc temperature due to the eddy currents would be very small and negligible.

Material Selection

Disc Material

The Disc will be machined from a 7075 Aluminum plate. Due to the disc spinning at very high angular velocities we will need to utilize a very strong material while maintaining its structural integrity. If in further analysis of the ECBS we determine another material better suited we will conduct analysis and make a decision accordingly.

Table 3: Disc Material Properties

Material Ult. Tensile strengt

h

Yield Strengt

h

Poisson’s Ratio

Shear Strengt

h

Shear Modul

us

Electrical Resistivit

y

7075-T651

Aluminum

83.0 kpsi

73.0 kpsi

0.330 48.0 kpsi

3.9 kpsi 0.00000203 ohm-

inch

6061- T6 Aluminu

m

45.0 kpsi

40.0 kpsi

0.330 30.0 kpsi

3.77 kpsi

0.00000157 ohm-

inch

Beryllium

Copper C17200-

TH04

190 kpsi

165 kpsi

0.300 N/A 7.25 kpsi

0.00000272 ohm-

inch

Electromagnet Core Material

We will make the Electromagnet cores out of a soft stainless steel, cut and machined by our team members, unless outsourcing is required. Soft stainless steel materials are generally low carbon high chromium and Molybdenum percentage steel with controlled additions of Silicon and Sulfur. The low carbon content of soft stainless steel allows for a high magnetic permeability which will allow the greatest magnetic effect by the electrical current, generated in the coils for maximum magnetic field strength. We are currently taking into consideration Kinetics MIM 2.5% SiFe Soft Magnetic Steel. This steel has high magnetic permeability and designed primarily for solenoid applications. Thorough research leads our team to believe this may be the best materials for cores but have not been provided with the material properties due to its dependence on geometry. Our team will conduct further investigation into selecting a suitable material for a solenoid core.

Wire/loop Material

We will use standard coated or tinned 20 gauge copper wire for the electromagnet coils. The number of coils along with the current will determine the force generated by the induced magnetic field. It is important for the conducting wire to contain a very small amount of resistance. The copper wire will give a sufficiently small amount of resistance.

PRACTICAL APPLICTION

Electric railway vehicle operation

During braking, the traction motor connections are altered to turn

them into electrical generators. The motor fields are connected across

the main traction generator (MG) and the motor armatures are

connected across the load. The MG now excites the motor fields. The

rolling locomotive or multiple unit wheels turn the motor armatures,

and the motors act as generators, either sending the generated current

through onboard resistors (dynamic braking) or back into the supply

(regenerative braking).

For a given direction of travel, current flow through the motor

armatures during braking will be opposite to that during motoring.

Therefore, the motor exerts torque in a direction that is opposite from

the rolling direction.

Braking effort is proportional to the product of the magnetic strength

of the field windings, times that of the armature windings.

Savings of 17% are claimed for Virgin Trains Pendolinos. There is

also less wear on friction braking components. The Delhi Metro saved

around 90,000 tons of carbon dioxide (CO2) from being released into

the atmosphere by regenerating 112,500 megawatt hours of electricity

through the use of regenerative braking systems between 2004 and

2007. It is expected that the Delhi Metro will save over 100,000 tons

ofCO2 from being emitted per year once its phase II is complete

through the use of regenerative braking.

Another form of simple, yet effective regenerative braking is used on

the London Underground which is achieved by having small slopes

leading up and down from stations. The train is slowed by the climb,

and then leaves down a slope, so kinetic energy is converted to

"stored" potential energy in the station.

Electricity generated by regenerative braking may be fed back into the

traction power supply; either offset against other electrical demand on

the network at that instant, or stored in lineside storage systems for

later use.

Dynamic brake

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 streetcars.

This heat can be used to warm the vehicle interior, or dissipated

externally by large radiator-like cowls 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 and increased maintenance cost of the

lines. 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.

Kinetic Energy Recovery Systems (KERS) were used for the motor

sport Formula One's 2009 season, and under development for road

vehicles. However, KERS was abandoned for the 2010 Formula One

season. The Formula One Teams that used Kinetic Energy Recovery

Systems in the 2009 season are Ferrari, Renault, BMW, and McLaren.

One of the main reasons that not all cars use KERS is because it adds

an extra 25 kilograms of weight, while not adding to the total car

weight, it does incur a penalty particularly seen in the qualifying

rounds, as it raises the car's center of gravity, and reduces the amount

of ballast that is available to balance the car so that it is more

predictable when turning. FIA rules also limit the exploitation of the

system. Eventually, during the season, Renault and BMW stopped

using the system. Williams is developing a flywheel-KERS system.

The concept of transferring the vehicle’s kinetic energy

using Flywheel energy storage was postulated by physicist Richard

Feynman in the 1950s 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 and Flybrid are both licensees of Torotrak's technologies, which

employ a small and sophisticated ancillary gearbox incorporating

acontinuously 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.

the importance of a good braking system. The demands of the road

and the weight of cargo can make it difficult and costly to keep

service brakes in good working order. Truckers using a FRENELSA

Electromagnetic Brake Retarder easily discover how it saves money

by increasing the lifespan of service brakes while increasing the safety

of the truck on road. 

People who have seen the Electromagnetic Brake are impressed with

the added safety it can provide to commercial and private vehicles.

A FRENELSA Electromagnetic retarder used properly can provide up

to 85% of your braking needs which reduces the use of your service

braking system and the environmental impact due to brake dust. This

decreased use of service brakes increases their lifespan while

improving safety on the road and cost savings.

OVERVIEW

Conventional Brake For Vehicle

Regular wear and tear of brake pads. High force and noise at high speed. Need regular maintenance and changing of brake pads required. Low efficiency

Eddy Current Brake For Vehicle

Low force and no noise. No wear and tear. Smooth application.

THEORETICAL

TESTING

Testing And Inspection

The testing and inspection procedure are laid down in such a way that

equipment manufactured by a passes though all the simulation test,

which may out instrument be subjected to in actual use. After a

careful study we have laid down the final tests.

1) VISUAL INSPECTION TEST

This test in a primary test to see the any physical damage.

1.1) PCL inspection

1.2) Mechanical strength

1.3) Input/ output connection scheme.

2) ASSEMBLY TEST

This test will cover all the functional test.

2.1) Components test

2.2) Circuit operation test using the test point signal.

3) FINAL TEST

This test will be carried out with the actual operation and conditions.

4) MECHANICAL VIBRATION TEST

This test will be done on the batch samples only.

Testing

Testing play a most important role in the manufacturing of any

product, which defects the invisible defects and confirms the desired

technical features of product.

During testing product is subject to various type of testing.

A) VISUAL CHECK

In this it is seen that all components of proper values are

mounted to their respective polarities.

B) CRCUIT TESTING

In this circuit is given to the required supply and various

parameters i.e. voltage current etc. are recorded and then is kept on

for cycle operation that is for 24 hrs. and parameters are recorded

after a certain intervals.

Types Of Test

Generally this test is conducted on one prototype job which

covers following stages :-

DAMP TESTING

`In this testing job is subjected to a wet atmosphere for one

cycle at a designed temperature and afterwards immediately normal

testing is conducted and observed that reading are in line with desired

readings.

On completing the testing the various stages readings are completed with designed parameters for necessary approval

OPERATIONAL

APPLICATION

The equipment has been in use for emergency braking since 2000, but only on authorised routes where the signalling and train control systems permit it. Service braking began on the Köln - Frankfurt Neubaustrecke in the summer of 2002, and since 2006, the brakes have also been used for service applications on the Nürnberg - Ingolstadt line. Both routes have LZB cab-signalling and are laid with ballastless slab track, which gives a stronger infrastructure to resist the heat in the rails generated by the braking forces.

When the trains are not operating on an approved section of line, the eddy-current brake must be deactivated by the driver. Extension of service braking to other routes is being considered, but this will require a detailed assessment of the infrastructure and other compatibility issues. The first commercial application outside Germany is on LGV Est, where the ICE3s are now certified to use their eddy-current brakes for service braking on the whole of the new line between Baudrecourt and Vaires. This is subject to a braking force limit of 105 kN, due to a perceived risk of interference with the TVM 430 train control system.

How is Safety Improved?

By providing up to 85% of a vehicle’s stopping needs, an Electromagnetic Brake keeps service brakes at cooler temperatures by reducing their use. Since Service brakes are more effective at cooler temperatures, a vehicles safety is improved when the service brakes are most needed - thus reducing the possibility of rear end collisions and other accidents due to brake failures. 

This decreased use of service brakes can increase their lifespan up to 7 times while improving safety on the road which results in huge cost savings. 

Heavy Duty Electric Brake Systems, Inc. is a recognized distributor of the secondary braking system FRENELSA Electromagnetic Braking system in the automotive and trucking industry throughout the world. 

Heavy Duty Electric Brake Systems works independently with each client to meet their needs and provide them with outstanding customer service.

Cost And Benefits

After the eddy-current brake had been put into regular commercial operation on the Koln - Frankfurt line, Deutsche Bahn (German National railway Company) began to look at the costs and benefits. A detailed three-month investigation in 2002 established that the use of the eddy-current brake for service applications resulted in a substantial reduction in the wear of the trains' conventional brake disks. At present DB spends around €2 million a year replacing worn brake linings on the ICE3 fleet alone, so there are obviously significant potential savings if the use of eddy-current brakes can be extended.

According to DB, the cost of the eddy-current brake can be recouped over seven years, thanks to the savings in operating and maintenance costs. Life-cycle costs over a nominal 25 years are expected to be little more than half of those for conventional disc brakes.

It seems fairly clear that the use of eddy-current brakes will be expanded in Germany over the coming years. DB has already decided that its next concrete project will be to modify the Stuttgart - Mannheim line to permit its use in regular service.

Clearance to use the technology elsewhere in Europe is less certain, as the same interference and compatibility issues also arise. A detailed examination of each route would be needed, and in some cases infrastructure components may have to be changed. It is perhaps instructive to note that apart from LGV Est, there has been no attempt yet to introduce eddy-current braking on any other routes in Europe's expanding high speed network. Nevertheless, regulatory provision has been made for this in the infrastructure, rolling stock and operation sections of the High Speed TSI.

ADVANTAGES

 Reduction of overall wastage of energy.

Increase in the mileage of the vehicle.

Less mechanical wear and tear.

The small amount of energy lost with this mechanism can be

diverted to useful one.

Regenerative braking even supplies back the energy it

consumes back to the system for future use.

In city driving, about 30 percent of a typical car's engine

output is lost due to braking. This can be reduced by using

electric breaking.

Predictable and Scalable Torque

Operates at any angular velocity

Conclusion

Thus, we have concluded that with the use of electric braking,

we would be able to conserve energy as well as maintain the

longevity of machine and vehicle parts.The reliability and

accuracy of an equipment is inversely proportional to the

number of components being used. The less number of the

components more reliability and accuracy can be achieved

almost of the electronic components are temperature and voltage

variation dependent. So more number of component more the

problem, you have also it increase the maintenance cost.

Our equipment has been designed using the most modern LSI

chips available in the market which can take the voltage fluctuation of

greater degree.

Cost Analysis

Valeo – Telma electrical system is a corporation of france design and manufacture eddy current brake for heavy vehicles eg. Buses, trucks and containers etc.

The average cost of ECBS manufactured by Valeo Telma is 2400US $. i.e. 115,000 Rs.

These 115,000 Rs. is an additional cost in the cost of trucks and buses.But after addition of ECBS, The Brake servicing cost reduces 3 times, that means ,A truck with conventional brake needs servicing of brake shoes after every 4 months and each servicing take approx Rs.10000 to Rs.12000. i.e. Rs. 36,000 per year in Brake maintainence.

After adding ECBS in the same vehicle , this braking maintainence cost reduce to Rs. 12000 in a year. i.e. Saving of Rs. 24000 per year.In 4.8. years , our cost of ECBS is balanced.And Safety is also improved by adding ECBS to the vehicle.

According to Zehengzhon Zhize corp. Ltd. Corporation of China, if ECBS is added in Cars then it will add an extra amount of 2300US $ in the cost of car. i.e. Rs. 11040 – Rs. 12000.

Braking maintainence of car consume approx. Rs. 4000 in a year, and brake shoes must be replaced after every 5000 km or 2 years.If we consider same condition same condition for car also, that means our braking cost reduce to Rs. 1000 to Rs. 1500 per year after adding ECBS in car, and life of brake shoes is also increased from 2 years to 6 -7 years.

We can save Rs. 3500 per year in case of car, there for cost of ECBS is balanced in 3.1 years.

Result

After adding ECBS in Heavy vehicles we can save Rs. 24000 per year, and if we consider life of truck is 20 years, then we can save Rs. 3,65,000 in braking maintainence.

If ECBS is added in cars also then Rs. 3500 braking maintainence cost can be save per year, We can save Rs. 70,000 braking maintaince cost in the whole life of car.

ECBS is a good accessory for vehicle due to some more following reasons:

1. Non-mechanical (no moving parts, no friction)2. Fully resettable, no parts need be replaced3. Can be activated at will via electrical signal4. Very Low maintenance5. Operates at any rotational speed

 

Reference

Sears, Francis Weston; Zemansky, Mark W. (1955). University Physics (2nd ed.). Reading, MA: Addison-Wesley.

Siskind, Charles S. (1963). Electrical Control Systems in Industry. New York: McGraw-Hill, Inc.. ISBN 0-07-057746-3.

Wirbelstrombremse im ICE 3 als Betriebsbremssystem hoher Leistung" ("Eddy-current brake in the ICE 3 as high-efficiency service brake system", by Jürgen Prem, Stefan Haas, Klaus Heckmann, in "electrische bahnen" Vol 102 (2004), No. 7, pages 283ff

www.ansoft.com/firstpass/pdf/ analysis_of_ eddy _ current _ brakes

http://zzzhize.en.alibaba.com/productshowimg/543564889- 213135109/Eddy_Current_Retarder_for_auto_parts.html