bullet trains and magnetic levitation and linear induction motor

1. Submitted to:-
Dr.Sushma gupta
1
Submitted by:-
K.Harish

2. What are linear motors?
Linear motors are electric induction motors that produce motion in a straight line
rather than rotational motion. In a traditional electric motor, the rotor (rotating
part) spins inside the stator(static part); in a linear motor, the stator is unwrapped
and laid out flat and the "rotor" moves past it in a straight line. Linear motors
often use superconducting magnets, which are cooled to low temperatures to
reduce power consumption
2

3. Construction of a Linear Induction Motor
Construction wise a LIM is similar
to three phase induction motor.If the
stator of the poly phase induction
motor shown in the figure is cut
along the section a-o-b and laid on a
flat surface, then it forms the
primary of the LIM housing the
field system, and consequently the
rotor forms the secondary consisting
of flat aluminium conductors with
ferromagnetic core for effective flux
linkage.
3

4. 4

5.  There are several ways and types of construction of a
Linear Motor or Linear Induction Motor.
 The simplest form of construction of a Linear Motor
is similar to the three phase induction motor.
 It has three phase winding housed in slots in a field
system.
 It is simply the primary winding on a stator in case of
an induction motor.
5

6.  The rotor is made by aluminum or copper plates in
parallel.
 In order to complete the flux path a ferromagnetic
material is placed with the plates.
 As the primary is on vehicle or object and secondary
is in form of plates so they will have unequal length.
 Normally two sided primary winding is used. In this
configuration the two field system, one on either side
of secondary are used.
6

7. Components of Linear Motors
•Forcer (Motor Coil)
Windings (coils) provide current (I)
Windings are encapsulated within
core material
Mounting Plate on top
Usually contains sensors (hall effect
and thermal)
•Magnet Rail
Iron Plate / Base Plate
Single or double rail F =
lI x B
7

8. Types of Linear Motors
1. Iron Core
2.Ironless Core
3. Slot less Core
8

9. Distinguishing Feature
• 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 (aka velocity ripple)
Iron PlateRare earth magnets
Laminated forcer
assembly and mounting
plate
Coil wound Around
Forcer lamination
Hall effect
and thermal
sensors
1. Iron Core
9

10. Distinguishing Feature:
• Forcer constructed of wound coils held
together and running between two rails
(North and South)
• Also known as “Air core” or “U-channel”
motors
Advantages:
• No attractive forces in forcer
• No Cogging
• Low weight forcer - No iron means higher
accel/decel rates
Disadvantages:
• Low force per package size
• Lower Stiffness; limited max load without
improved structure
• Poor heat dissipation
• Higher cost (2x Magnets!)
Top View
Forcer
Mounting
Plate
Rare
Earth
Magnets
Horseshoe
Shaped
backiron
Winding, held
by epoxy
Hall Effect and
Thermal
Sensors in coil
Front View
2. Ironless
10

11. 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
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
3. Slot less
11

12. Working of a Linear Induction Motor
When the primary is excited by a balanced three phase supply, a
rotating electromagnetic flux is induced in primary.
The synchronous speed of the field is given by the equation :
ns=2 fs/p
Here, fs is supply frequency in Hz,
p is the number of poles,
ns is the synchronous speed of the rotation of
magnetic field in revolutions per second.
The developed field will results in a linear travelling field, the
velocity of which is given by the equation,
vs=2 t fs meter/second.
Here, vs is velocity of the linear travelling field,
t is the pole pitch.
12

13. For a slip of s, the speed of conducting slave in a linear
motor is given by
vr=(1-s)vs
Linear Induction Motor is
similar in construction to a
circular motor that has been
opened out flat.
The magnetic field now
sweeps across the flat motor
face instead of rotating.
13

14. Components of a “Complete” Linear Motor
System
1. Motor components
2. Base/Bearings
3. Servo controller/feedback
elements
• Typical sensors include Hall Effect
(for position) and thermal sensors
4. Cable management
14

15. Benefits of Linear Motors
• High Maximum Speed
• Fast Response
Response rate can be over 100 times that of a mechanical
transmission faster accelerations & deceleration.
• Stiffness
No mechanical linkage, stiffness depends mostly on gain &
current
• Durable
Modern linear motors have few/no contacting parts no wear
15

16. Downsides of Linear Motors
 Cost
More capital cost
Cost increases with length
Lower force per package size
 Heating issues
Forcer is usually attached to load I2R losses are directly coupled to load
16

17. Applications
• Small Linear Motors
• Packaging and Material Handling
• Automated Assembly
• Reciprocating compressors and
alternators
• Large Linear Induction Machines
(3 phase)
• Transportation
• Materials handling
• Extrusion presses
17

18. It was the first LIMTV designed in 1973
18

19. 19

20. what is meant by maglev ?
20

21. the use of the physical properties of magnetic fields
generated by superconducting magnets to cause an
object(vehicle) to float above a solid surface.
Photo: NASA tests a prototype Maglev railroad21

22. 22

23. 23

24. 24

25. 25
How much power do Maglev trains
use?
Weight: The electromagnets in many EMS and
EDS designs require between 1 and 2 kilowatts
per ton. The use of superconductor magnets can
reduce the electromagnets' energy consumption.
A 50-ton Transrapid maglev vehicle can lift an
additional 20 tons, for a total of 70 tons, which
consumes 70–140 kW (94–188 hp).

26. The world's first commercial maglev system was a low-speed maglev shuttle that ran
between the airport terminal of Birmingham International Airport and the
nearby Birmingham International railway station between 1984 and 1995. Its track length
was 600 m (2,000 ft), and trains levitated at an altitude of 15 mm (0.59 in), levitated by
electromagnets, and propelled with linear induction motors.
26

27. 27

28. • It is the latest application of MAGLEV+LIM. It’s speed
is 603 kilometers per hour or 375 miles per hour.
28

29. 29

30. 30