Eddy current brakes work by generating eddy currents in a conductive material using a changing magnetic field from electromagnets. These eddy currents then generate their own magnetic field that opposes the original field due to Lenz's law, creating drag and slowing the object. There are circular and linear eddy current brake configurations. Advantages include being contactless with no wear, adjustable braking force, and effectiveness even at high speeds. Applications include train braking and roller coasters. Future developments could replace ordinary brakes and control high speed trains solely with eddy current brakes.

1. EDDY CURRENT BREAKING
PRESENTED BY
SACHIN PRAKASH
U10EE084
ELECTRICAL DEPARTMENT

2. CONTENTS
• Introduction
• Theory Of Operation
• Working Principle
• Constructional Details
• Classification of eddy current brakes
• Advantages & Disadvantages
• Applications
• Conclusion

3. What is Induction?
– “The induced electromotive force in any closed circuit is equal
to the negative of the time rate of change of the magnetic flux
through the circuit.”
• Lenz’s Law
– Why circuits obey Newton’s third law along with the
conservation of energy
– “An induced electromotive force (emf) always gives rise to a
current whose magnetic field opposes the original change in
magnetic flux”

4. Eddy Current Brakes
• It slow an object by creating eddy currents
through emi which create resistance, and in
turn either heat or electricity.
• Braking action is made by varying the strength
of the magnetic field.
• A braking force is possible when electric current is
passed through the electromagnets.

5. Induction Currents = Eddy Currents
• Called “Eddy” since they are analogous to fluid eddies in
formation and behavior
• Responsible for the opposing magnetic fields that produce
drag and heating effects
• The drag effects give rise to induction braking
– Absent external potentials will result in the system coming to a
halt
• Heating effects are exploited by devices such as induction
cookers
– If left unchecked, then it could result in serious damage to
mechanical/circuit components

6. Check on Heat Effects
• High voltage circuits are constructed as a
series of “laminations” to reduce eddy
currents
• Solid conductors would suffer increased
resistivity and large energy losses (heat)

7. Drag Effects: Magnetic Braking
• Not to be confused with stellar magnetic braking
– The primary reason for slow stellar rotations
• Utilized in many practical applications:
– Trains (Maglev and conventional) as a braking system
– Some roller coasters
– Braking Industrial equipment and power tools
– Some exercise equipment
• Rowing or Spin machines… to increase resistance
– Determining structural defects in conductive materials
– Metal Detectors

8. THEORY OF OPERATION
• Eddy current brakes develop torque by the direct
magnetic linking of the rotor to the stator.
• This linking generates eddy currents in the driven rotor.
• Eddy current brakes must have a slip between the
rotor and the stator to generate torque.
• An eddy current brake having an electromagnetic pole
and the rotor is positioned in close proximity to the
stator with an air gap between them

9. ⚫The stator comprises steel pole pieces with hollow cores
that establish a magnetic circuit for a magnetic flux field.
⚫ The pole pieces have machine-wound electrical windings.
⚫ The windings are fastened with pole caps.
⚫The hollow core reduces the weight and material of the
stator without significantly adversely affecting the braking
capacity.
⚫The pole caps reduce the magnetic saturation and increases
the overall brake torque output.

10. HOWDOTHEY W
ORK??

12. Working Principle
• Electromagnets produce magnetic field from
supplied current
• Change of magnetic flux (with time) induces eddy
currents in conductor (disc)
• Eddy Currents produce another magnetic field
opposing first field
• Opposing magnetic fields create force that
reduces velocity

13. Magnetic field lines across the
magnetic material inside a copper
tube

14. Direction of magnetic lines of force
due to magnet in copper tube

16. ARRANGEMENT OF DIFFERENT PARTS
IN EDDY CURRENT BRAKE

17. Types of Eddy current brake
• Circular eddy current brake
• Linear eddy current brake

18. CIRCULAR EDDY CURRENT BRAKING
SYSTEM
non-ferromagneticmetaldiscs(rotors)areconnectedtoa
rotatingcoil,andamagneticfieldbetweentherotorand
thecoilcreatesacurrentusedtogenerateelectricity
whichproduces heat.
W
h
e
nelectromagnets areused,controlofthebraking
actionismadepossiblebyvaryingthestrengthofthe
magneticfield.

19. Themovementofthemetalthroughthemagneticfieldof
theelectromagnetscreateseddycurrentsinthediscs.
Theseeddycurrentsgenerateanopposingmagneticfield
(Lenz'slaw),whichthenresiststherotationofthe
discs,providingbrakingforcew
hichdecelerate the
moving system.
Thenetresultistoconvertthemotionoftherotorsinto
heatintherotors.

20. Circular eddy current brakes

21. Linear eddy current brakes
ItisfirstdescribedbyFrenchphysicistFoucault.
Thelineareddycurrentbrakeconsistsofamagneticyokewith
electricalcoilspositionedalongtherail,whicharebeing
magnetizedalternatingassouthandnorthmagneticpoles.
Thismagnetdoesnottouchtherail,aswiththemagneticbrake,
butisheldataconstantsmalldistancefromtherail
(approximatelysevenmm).

22. W
henthem
agnetism
ovedalongtherail,itgeneratesanon-
stationarym
agneticfieldintheheadoftherail,w
hichthen
generateselectricaltension(Faraday'sinductionlaw),andcauses
eddycurrents.
Thesedisturbthemagneticfieldinsuchawaythatthemagnetic
forceisdivertedtotheoppositeofthedirectionofthemovement,
thuscreatingahorizontalforcecomponent,whichworksagainst
them
ovementofthem
agnet.

23. Linear Eddy Current Brake

24. Advantages. . .
 Independent of wheel/rail adhesion.
 No contact, therefore no wear or tear.
 No noise or smell.
 Adjustable brake force.
 High brake forces at high speeds.
 Used also as service brake.
 It uses electromagnetic force and not friction
Non-mechanical (no moving parts, no friction)
Can be activated at will via electrical signal
Low maintenance
Light weight

25. DISADVANTAGES:-~
Braking force diminishes as speed diminishes
with no ability to hold the load in position at
standstill.
It can not be used at low speed vehicles or
vehicle running at low speed.
ECB is used with ordinary mechanical brakes.
Nowdays ECB is using only for safety purpose.

26. Applications
 It is used as a stopping mechanism in trains. Ex-
Japanese Shinkansen trains
 It is also used in the smooth breaking and
functioning of roller coasters and such fast
moving machines.
Ex-Intamin roller coaster in Netherlands.
 To eliminate vibration from spacecraft.

27. Future Aspects
In future ordinary brakes can be replaced by
the ECB completely.
By the use of ECB in future we can control
high speed train completely.
By some new invention of extra mechanism
we can use ECB for slow speed vehicles also.

28. CONCLUSION
 The ordinary brakes which are being used now days,
stop the vehicle by means of mechanical blocking. This
causes skidding and wear and tear of the vehicle. If the
speed of the vehicle is very high, it cannot provide that
much high braking force and it will cause problems.
 These drawbacks of ordinary brakes can be overcome
by a simple and effective mechanism of braking system
'The eddy current brake'.
 It is an abrasion-free method for braking of vehicles
including trains. It makes use of the opposing tendency
of eddy current

29. THANK YOU