This seminar presentation summarizes the key aspects of linear induction motors (LIMs). It discusses the construction of LIMs, including their stator and rotor components. It describes the different types of LIMs according to their core shape, including iron core, ironless core, and slot-less designs. The presentation also covers the principles of operation of LIMs, the different forces involved, and various effects such as end effects and gap effects. It compares LIMs to conventional induction motors and rotary induction motors, outlines the advantages and disadvantages of LIMs, and discusses applications such as transportation and material handling where LIMs are commonly used.

1. A SEMINAR PRESENTATION
ON
2015-2016
ELECTRICAL ENGINEERING
RAJASTHAN TECHNICAL UNIVERSITY, KOTA
Ajit Singh Rajawat
Branch: PEC & ED
M.Tech.(III Semester)
Dr. Dinesh Birla
Dr. Vivek Shrivastava
Electrical Department
Presented To :- Presented By :-
Linear Induction Motor(LIM)
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2. CONTENTS
• Construction of LIM
• Types of LIM
• Principle of LIM
• Forces in LIM
• Various effects in LIM
• Comparison between CIM/RIM & LIM
• Advantage of LIM
• Disadvantage of LIM
• Various application of LIM 2

3. CONSTRUCTION OF LIM
• Cut down rotor to form secondary Winding
• Stator Winding
• Rotor metal
• Length of rotor & stator
3

4. TYPES OF LIM
• DLIM• SLIM
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5. TYPES OF LIM: ACCORDING TO CORE SHAPE
• Iron Core
– Coils wound around teeth
of laminations on
forcer(LIM core).
• Ironless Core
– Dual back iron separated
by spacer
– Coils held together with
epoxy(resin for lamination).
• Slot-less
– Coil and back iron held
together with epoxy.
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6. Iron PlateRare earth magnets
Laminated forcer
assembly and mounting
plate
Coil wound Around
Forcer lamination
Hall effect
and thermal
sensors
IRON CORE LIM
Features:
• Copper windings around forcer laminations over a single magnet rail
Advantages:
• Highest force available per unit volume
• Efficient Cooling
• Lower cost
Disadvantages:
• High attractive force between forcer & magnet track
• Cogging: iron forcer affects thrust
force as it passes over each
magnet.
• Heavy in weight.
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7. Features:
• Forcer constructed of wound coils
held together with epoxy and running
between two rails (North and South)
• Also known as “Aircore” or “U-
channel” motors
Advantages:
• No attractive forces in forcer
• No Cogging
• Low weight forcer - No iron means
higher acceleration/deceleration rates
Top View
Forcer
Mounting
Plate
Rare
Earth
Magnets
Horseshoe
Shaped
backiron
Winding, held
by epoxy
Hall Effect and
Thermal
Sensors in coil
Front View
IRONLESS LIM
Disadvantages:
 Low force per package size
 Lower Stiffness; limited max load without improved structure
 Poor heat dissipation
 Higher cost (2x Magnets)
Side View
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8. Features:
• Mix of ironless and iron core: coils
with back iron contained within
aluminum housing over a single
magnet rail
Advantages over ironless:
• Lower cost (1x magnets)
• Better heat dissipation
• Structurally stronger forcer
• More force per package size
Advantages over iron core:
• Lighter weight and lower inertia forcer
• Lower attractive forces
• Less cogging
Side View
Front View
Back
iron
Mounting
plate
Coil
assemblyThermal
sensor
Rare
Earth
Magnets
Iron
plate
SLOT-LESS LIM
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9. Disadvantages
• Some attractive force and
cogging
• Less efficient than iron core
and ironless - more heat to do
the same job
Side View
Front View
Back
iron
Mounting
plate
Coil
assemblyThermal
sensor
Rare
Earth
Magnets
Iron
plate
SLOT-LESS LIM(CONT.)
Side View
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10. Linear Brushless DC Motor Type
Feature Iron Core Ironless Slotless
Attraction Force Most None Moderate
Cost Medium High Lowest
Force Cogging Highest None Medium
Power Density Highest Medium Medium
Forcer Weight Heaviest Lightest Moderate
LINEAR MOTOR TYPE COMPARISON
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11. PRINCIPLE OF LIM
• Analysis is similar to that of RIM
machines
a. Linear dimension and
displacements replace angular
ones
b. Forces replace torques
c. Commutation cycle is distance
between two consecutive pole
pairs instead of 360 degrees
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12. FORCES IN LIM
• NORMAL FORCE
• LATERAL FORCE
• THRUST FORCE
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13. NORMAL FORCE
1. In DLIM motors, normal force between one stator & reaction plate is equal
and opposite to the normal force generated by second stator and reaction
plate. So in maximum DLIM, the net normal force is equal to zero.
2. This force shows the asymmetry of the system.
3. In SLIM, there is large net normal force because of fundamental asymmetry
topology.
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14. LATERAL FORCE
1. These forces are acted on perpendicular to the rotor position
which in Y-direction.
2. These forces makes system unstable because they provide high
frequency(>>60Hz) operation of the system.
3. Lateral forces can be eliminated by using some guided motion
of wheel of LIM.
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15. THRUST FORCE
1. This force is generally provides motion for the system
2. Thrust is proportional to square of applied voltage & this can be
reduced by reducing the slip of motor by increasing rotor resistance.
𝐹𝑠 =
𝑃𝑜
𝑣 𝐶
Where 𝑃𝑜 is mechanical power transmitted to the rotor
𝑣 𝐶 is the speed of rotor.
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16. VARIOUS EFFECTS IN LIM
• End Effect
• Edge Effect
• Gap Effect
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17. END EFFECT
1. Travelling magnetic field cannot
join up on itself, and introduces
end effects in LIM.
2. It produce a non-uniform flux
density distribution along the
length of the motor.
3. By increasing the number of poles,
the end effects are reduced 17

18. EDGE EFFECT
1. The figure shows a dip at the
centre due to the edge effect,
and the dip is more obvious
at higher slips.
2. The edge effect will increase
the secondary resistivity.
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19. GAP EFFECT
1. CIM has a very small air gap order of 2mm or less.
2. In the case of LIM, Air gap is the order of 5cm for traction
purpose.
3. Due to large air gap, Motor having large reluctance and
losses. So efficiency is low in comparison of CIM
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20. ADVANTAGE OF LIM
• No gear Requirement(No need to mechanical
rotatory-to-linear converter)
• Economical & Cheap Maintenance
• High acceleration/deceleration
• Simple in structure
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21. DISADVANTAGE OF LIM
• Power factor and efficiency
• Extra vibrations with distortions
• End effect
• Large Air-gap
• High in cost
• Heating Issues
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22. APPLICATION OF LIM
• Small Linear Motors:
a. Conveyor systems
b. Airport baggage handling
c. Accelerators and launchers
d. Pumping of Liquid metal
• Large Linear Motors:
a. Transportation(Low & Medium Speed trains)
b. Sliding Doors Closure(Malls, Metros)
c. People movers
d. Material handling and storage 22

23. FUTURE SCOPE
• Improving the equivalent circuit model of the LIM by
introducing various realistic factors Like End effect, Edge
effect, Air-gap flux etc.
• The LIM is designed and analysed in its steady state only. The
transient behaviour of the LIM is not analysed in this study.
• Improvements to the proposed model can be suggested by
trying different winding configurations.
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24. CONCLUSION
• In this PPT, a detailed study of the design of the LIM was
performed and compared with that of a comparable CIM design.
• The air-gap needs to be as small as possible to have a better thrust
and efficiency.
• As the thickness of the aluminium sheet is increased thrust also
increases along with the length of magnetic air-gap.
• These are the key parameter for LIM Performance(the length of
physical air-gap, the thickness of aluminium sheet and the number
of poles)
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25. REFERENCES
[1] Theory and performance of Electrical Machines- J.B.Gupta / edition/ Published by
S Kataria & Sons.
[2] J. Barrett, T. Harned, J. Monnich, Linear Motor Basics, Parker Hannifin Corporation,
http://www.parkermotion.com/whitepages/linearmotorarticle.pdf
[3] Trilogy Linear Motor & Linear Motor Positioners, Parker Hannifin Corporation, 2008,
http://www.parkermotion.com/pdfs/Trilogy_Catalog.pdf
[4] “Descriptor-Type Kalman Filter and TLS EXIN Speed Estimate for Sensorless
Control of a Linear Induction Motor”Published by Francesco Alonge, Maurizio
Cirrincione, Filippo D’Ippolito, Marcello Pucci, Antonino Sferlazza, and
Gianpaolo Vitale in IEEE Journals on 6th Nov./Dec. 2014.
[5] “The linear induction motor (LIM) & single linear induction motor (SLIM)”
Published by Nahid Ahmadinia in American Journals on 20th July 2014.
[6] “Neural Sensorless Control of Linear Induction Motors by a Full-Order Luenberger
Observer Considering the End Effects”Published by Angelo Accetta, Maurizio
Cirrincione, Marcello Pucci, and Gianpaolo Vitale in IEEE Journals on 3h
May/June 2014.
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26. Thank You
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