Electromagnetic Levitation Demonstrator.
"I have read this thesis and in my opinion, it is suitable in term of scope and quality for
the purpose of awarding Bachelor Degree in EJectronic Engineering ( Industrial
EJ
Signature
Name of Supervisor
Date
ni )
ELECTROMAGNETIC LEVITATION DEMONSTRATOR
ｒｕｓｍｅｙａｔｉｂｾｎｏｄ＠
This Report Is Submitted In Partial Fulfillment Of Requirements For The Bachelor
Degree of Electronic E ngineering ( Industrial Electronic)
Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer
Kolej Universiti T ekrnlcal Kebangsaan Malaysia
March 2005
Jl
"I hereby declare that this thesis is the result of my own effort except as clearly stated in
the sources of reference"
Signature
Writer
Date
Rusmeyati binti Nordin
l APP. \ L 2 0 oS
llJ
First and foremost, I would like to express my deepest gratitude to my supervisor Mr.
Ho Yih Hwa for his supervision and invaluable guidance throughout this work.
I am most grateful to my lovely parents for being understanding and supportive in
whatever decision I made.
A special thanks to En. Mohd Razi bin Y aacob for his supported and En. Aini for his
k:ind.Jy assistance in providing all the necessary equipment in this project.
JV
ABSTRACT
Electromagnetic Levitation System had become a fast develop technologies
providing environmentally benefit solutions for industry and transportation. This project
is develop a Electromagnetic Levitation Demonstrator consist of two photo-detector and
one lifting coil. It is demonstrated how an electromagnetic can floating I pulls a steel ball
upward Wltil it interrupts a light beam that falJs on the photo-detector and how the coil
effect to electromagnetic levitation demonstrator but this system can only reach out a
few short centimeter and anything further might as well be infinity. This device need a
design and construct the circuit such as the coil driver and the different amplifier circuit,
Infrared emitter and Photo-detector ciicuit, the reference voltage and phase lead network
circuit and need to design the lifting coil
v
ABSTRAK
Sistem Pengapungan Elektromagnetik menjadi satu tecknologi yang berkembang
pesat dan menyediakan pelbagai faedah penyelesaian untuk industri dan pengangkutan.
Projek ini menunjukkan Sistem Pengapungan Elektromagnetik yang terdiri daripada dua
pengesan cahaya dan satu gegelung pengangkat Ia menunjukkan bagaimana
elektomagnetik tersebut boleh mengapungkan I menarik bebola Jogam naik ke atas
hingga biasan sinar cahaya terhadap pengesan cahaya yang akan menjatuhk:annya dan
bagaimana gegelung pengangkat akan memberi kesan kepada penunjuk
Sistem
Pengapungan Elektomagnetic ini. Sistem ini hanya boleh digunakan untuk jarak yang
.
pendek iaitu dalam beberapa sentimeter dan sebarang tambahan jarak seterusnya akan
menjadi ifiniti. Projek ini memerlukan rekaan dan susunan litar seperti litar pemacu
gelung, htar penguat pembezaan, litar pemancara inframerah, litar pengesan cahaya, litar
untuk voltan rujukan, litar penunjuk fasa dan memerlukan rekaan bagi gegelung
pengangkat.
Vl
CONTENT
CHAPTER
PAGE
TITLE
PROJECT TITLE
I
n
ACKNOWLEDGEMENT
11
DEDICATION
111
ABSTRACT
IV
ABSTRAK
v
CONTENT
VI
LIST OF TABLE
IX
LIST Of FIGURE
X
INTRODUCTION
l .l
Introduction
l
1.2
Project Objective
2
1.3
Scope Project
2
LITERATURE REVIEW
2.1
Introduction
3
2.1.1 Background of magnetic levitation
2.2.2
demonstrator
4
Electromagnetic Levitation
5
VI I
m
ELECTROMAGNETIC MODULE
3.1
Introduction
3.2
Flow Diagram of Electromagnetic
Levitation System
12
3.2.1
Input
12
3.2.2
Emitter
13
3.2.3
Signal Detector
14
3.2.4
Reference Detector
15
3.2.5
Difference AmpJifier
16
3.2.6
Loop Control
17
3.2.6.1 Benefit of Feedback
18
Loop Equations
19
3.2.7.1 Loop Gain
20
3.2.7.2 Transfer Function
21
3.2.8
Non Inverting Amplifier
22
3.2.9
Coil Driver
23
3.2.9.1 Specification for Lifting Coil
25
3.2.9.2 Coil Core
25
3.2.7
3.3
3.4
9
Power Supply
26
3.3.1 Coil Driver Supply
27
List of Component
28
3.4.1
Integrated Circuit IC LM741
30
3.4.2
Transistor NPN 2N3055
31
VlJJ
IV
RESIJLT
4.1
Introduction
33
4.1.1 Bode Plot of Phase Lead Network
33
4.2
Measurement
35
4.3
Design circuit at Printed Circuit Board
36
4.4
Casing
36
4.4.1 Material List
37
4.4
4.5
v
Electromagnetic levitation demonstrated
operation
38
How the Coil Wor1cs
39
DISCUSSION AND CONCLUSSION
5.1
Discussion
. 5.1.1
Winding Wire
41
41
5.1.2 Weight of the steel ball
42
5.2
Conclusion
42
5.3
Future Development
43
REFERENCE
45
APPENDIX
46
IX
LIST OF TABLE
NO.
TITLE
3.1
Voltage Requirements
3.2
List of Component and Equipment in
PAGE
27
Electromagnetic Levitation System
29
3.3
The Absolute Maximum Rating of LM741
31
3.4
Absolute Maximum Rating of Transistor
4.1
NPN2N3055
32
Material Jist
37
X
LIST OF FIGURE
NO
TITLE
2.1
An Electromagnetic
7
3.1(a)
Overall Process Flow
10
3.1(b)
Flow Process ofElectromagnetic Levitation System
11
3.2
Flow Diagram of Electromagnetic Levitation System 12
3.3
Emitter Circuit
13
3.4
Signal Detector circuit
14
3.5
Flow Diagram For Signal Detector to
.
PAGE
Voltage Follower
15
3.6
Reference Detector Circuit
15
3.7
Difference Amplifier Circuit
16
3.8
Feedback Control System
19
3.9
Transfer function Circuit
21
3.10
Non Inverting Amplifier circuit
22
3.11
Coil Driver Circuit
23
3.12
Transistor NPN 2N3055
24
3.13
Coil Core
26
3.14
Power Supply separated
28
3.15
Connection Diagram ofLM741
30
3.16
Internal Schematic Diagram of Transistor
4.1
NPN2N3055
32
Bode plot of Phase Lead Network
34
XI
4.2
Phase Lead Network Circuit
34
4.3
Signal and Reference Detector Measurement
35
4.4
Casing
37
4.5
Electromagnetic Levitation demonstrated
39
4.6
Coil Works
40
CHAPTER I
INTRODUCTION
1.1
INTRODUCflON
.
This thesis report on the design of the controller for keeping a steel ball
suspended in the air. In the ideal, the magnetic force produced by current from an
electromagnetic will counteract the weight of the steel ball. Nevertheless, the fixed
electromagnetic force is very sensitive, and there is noise that creates acceleration force
on the steel ball, causing the balJ to move into the unbalance region. The main function
of this controller is to maintain the balance between the magnetic force and the ball, s
weight According to the analytical method, the mathematical models of this magnetic
levitation system were established with the goal of designing the control system. System
linearization and phase lead composition were employed to design the controller of this
unstable nonlinear system. The algorithm proposed in this thesis provides a robust
closed-loop magnetic levitation system which can stabilize the system over a large range
of variations of the suspended mass. The design methods of this system are presented on
this thesis and the hardware is implemented for the scientific demonstration. Presented
in this thesis is about the magnetic levitation demonstrator which used two photo-
2
detector as a signal and reference, and a ljfting coil to produce magnetic field current to
pull a steel baH floating in the air.
1.2
PROJECT OBJECTIVE
The project objective is to demonstrated the concept of electromagnetic
levitation system by using two photo-detector and lifting coil and to produces the low
cost of electromagnetic levitation demonstrator. This electromagnetic levitation system
is selected and was build by follow their specification. The specification are to build a
magnetic coil which can produce an electromagnetic force carries with 2A of current,
and to definitely with Jess current the steel ball will move downward and when the high
current the steel baiJ will move upward
1.3
SCOPE PROJECT
This project built to studies and construct the emitter circuit, reference detector
circuit, photodetector circuit, different amplifier circuit, design the lifting coil, design the
signal detector circuit, design the non inverting amplifier circuit and design the phase
lead network circuit to demonstrate a steel ball float in the air.
CHAYrER
n
LITERATURE REVIEW
2.1
INTRODUCTION
This chapter discuss about how the steel ball can float in the air by using the
lifting coil and two photodetector which produce the magnetic force into this device.
The magnetic levitation demonstrator
is the simple structure an is based on
electromagnetic science by Sarnuel Earnshaw Theorem. In his theorem expressed the
perversity of inanimate of magnetic objects.
When we hold two permanent magnets close together, you see that one of them will
jump strongly toward from the other. It explains this frustrating behavior will
always prevent you from suspending otze permanent magnet above or below
another, no matter how one arranges the two magnets. However, an active control
circuit can get around this problem by rapidly adjusting the magnet's strength.
I 842. Samuel Earnshaw
4
The basic principles is to used a current to manipuJate electromagnetic power
which can counteract the weight of the steel ball and keep it suspended in the air.
2.1.1
BACKGROUND OF MAGNETIC LEVITATION DEMONSTRATOR
This magnetic levitation demonstrator is a technological advances in areas offer
the possibility of generating high electromagnetic fields with high efficiency. The
magnetic levitation was build to give the advance mode of surface high speed
transportation whereby a vehicles gliding above a guide way is suspended, guided and
propeJJed by magnetic force, which without the magnetic levitation the speed will be
slow, take a long time and high cost but with magnetic levitation. the speed become fast
and the time is Jess for example the Maglev trans-rapid Maglev is the short form for
magnetic levitation which
means the train will float at the guide way using the basic
principles of magnet to replace the old steel wheel and train tracks. Maglev trains float
on a cushion of air,
eliminating friction. This lack of friction and the trains
aerodynamic design allow the trains to reach unprecedented ground transportation speed
of more that 3 JOm ph. Besides that the magnetic levitation is a good technologies that
can reduce the pollution such as reduce air and highway congestion, air pollution and
petrolewn used.
5
2.1.2 ELECTROMAGNETIC LEVITATION
The electromagnetic system keeps a steel ball suspended in the air by countering
the balls weight with electromagnetic force which can be expressed as the dynamic
following formula in an upward direction according to Newton' s law.
F = mg
(2.1)
where m is the weight of the ball, g as a gravitational constant and F is the force produce
from electromagnetic coil. The magnetic field generated by current and calculated from
Ampere' s Law or Biot-Savart Law are characterized by magnetic field Band the unit is
in Testa. When the generated field pass through the magnetic materials which contribute
internal magnetic field, ambiguities can arise a part of the field from external current and
the materials. The magnetic ·field strength had defined as another magnetic field quantity
designated as H, and the relation ship is:
H = B / Jlo
(2.2)
and if the value of unambiguous designated the driving magnetic influence from extend
current in a material, independent of the material magnetic response. The relationship of
8 can be written in the equivalent form:
(2.3)
6
Hand M wiJI have the same units, amperes'/meter. The relationship in eq. (2.3) holds
for all material whether they are linear or not For linear materials, M in (Aim) depends
linearity on H such that
M = XmH
(2.4)
where Xm is a dimensionless quantity ( ratio of M to H ) called magnetic susceptibility
of the medium. It is more or less a measure of how susceptible or sensitive the material
is to a magnetic field Substituting eq. (2.4 ) into eq. (2.3) yields:
B = JJQ(J + Xm ) H = Jili
(2.5)
B = JJQ 14H
(2.6)
or
The quantity J.1 = JJo J.lr is called the permeability of the material and is measured in
henry's/meter, the henry is the unit of inductance and will be defined a little later. The
dimensionless quantity Jlr is the ratio of the permeability of a given material to that of
free space and is known as a relative permeability of the material and JJQ being the
magnetic free space permeability J.1o = 4n x l 0 -7. The magnetic force will produce the
electromagnetic flux for the magnetic circuit The magnetic force produce flux with I
which called as flux path.
H = IN II
(2.7)
7
/=27tr
for a circular path :
H=IN I 21tr
(2.8)
Force on magnetic material is the practical interest to determined the force that a
magnetic field exert on a piece of magnetic material in the field. This is useful in
electromechanical system such as electromagnetic levitation system. An electromagnet
made from iron of constant relative permeability as shown in Figure 2.1. The coil bas N
turn and carries a current I. with ignored the fringing, the magnetic field in the air gap is
the same as that in iron (
B1n = B2n ).
-I-
\
Ｍｾ＠
I I
---,
II
- tｾＭ I
1
l
ｾ ｝＠
I·
Figure 2.1: An Electromagnetic
To find the force between the two pieces of iron, the changed of total energy
were calculated that would result of the two pieces of magnetic circuit separated by a
differential displacement dl. The work required to effect the displacement is equal to the
changed the stored energy in the air gap ( assuming constant current ) that is :
-Fdl = dWm = 2 [ (1 I 2)( B2 ｉ ｾＩ＠
S dl]
(2.9)
8
where S is the cross-sectional area of a gap, the factor two accounts for the two air gaps.
And the negative sign indicates that the force acts to reduce the air gaps ( or that the
force is attractive). Thus
F = -2 ( B2 S / 2 J.1o)
(2.10)
The force is exerted on the lower piece and not and the cWTent-carrying upper piece
giving rise in to the field The tractive force across a single gap can be obtained from
eq.(2.10) as
(2 .11)
This equation can be used to calculated the forces in many types of devices including in
electromagnetic levitation system. The tractive pressure in ( N/m2 ) in a magnetic
surface is
(2.12)
Which is the same as the energy density Wm in the air gap
CHAPTERID
SYSTEM DESJGN
3.1
INTRODUCTION
.
This chapter explained about the overall process flow and construction to build
the electromagnetic levitation demonstrator in Figure 3.1(a) from start until progress the
fmal report, to design the circuit and to make sure the objectives of this project
successfully done. Figure 3. 1(b) show the flow process of electromagnetic levitation
system functioned and their specifications, This system used the looping system as phase
lead network to reduced the coil strength to allow the ball to go down but doesn't turn to
the coiJ until the ball is past the reference spot This system also used the transfer
function and looping feedback system.
10
Studies about tbe electromagnetic
background and idea modeling of the project
Collect the information of electromagnetic
levitation system such as information of
electromagnetic coil and photodetector
Design the flow diagram specification
module of Electromagnetic Levitation
Demonstrator
Testing and result of electromagnetic
levitation system including construct
discussion and conc1usion
Submitted the final report
Figure 3.l(a ): Overall Process Flow
11
Produces light beam and
carries 300mA cwrent.
ｾ＠
Transistor Q 1
received the signal
from infrared
emitter and carries
less current when
Q2 blocked
Transistor Q2
received the signal
from infrared
emitter and carries
high current when
QJ blocked
Consist of2 op-amp and
funftioned as voltage
fo1lower
Comparator
Phase lead network
Non Inverting Amplifier
received the signal :from
phase lead network
Coil Driver
produced the
electromagnetic
field
Figure 3.1( b ) : Flow Process of E1ectromagnetic Levitation System
12
3.2
FLOW DIAGRAM OF ELECTROMAGNETIC LEVITATION SYSTEM
'lin
Signal
(+)
Detector
Phase
Lead
Net-work
Different
Amplifier
ｾ＠
ｾ＠
Amplifier
Coil
ｖｯｾ＠
Figure 3.2: Flow Diagram of Electromagnetic Levitation With Looping Feedback
System
The flow diagram shoWn in Figure 3.2 explained about the process sequence for
electromagnetic levitation system which separated by eight stage start from input until
output. Each stage explained are :
3.2.1
INPUT
The type of the input voltage that used is direct current (DC). This
electromagnetic system used three input voltage for lifting coil and for integrated circuit
the purpose of awarding Bachelor Degree in EJectronic Engineering ( Industrial
EJ
Signature
Name of Supervisor
Date
ni )
ELECTROMAGNETIC LEVITATION DEMONSTRATOR
ｒｕｓｍｅｙａｔｉｂｾｎｏｄ＠
This Report Is Submitted In Partial Fulfillment Of Requirements For The Bachelor
Degree of Electronic E ngineering ( Industrial Electronic)
Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer
Kolej Universiti T ekrnlcal Kebangsaan Malaysia
March 2005
Jl
"I hereby declare that this thesis is the result of my own effort except as clearly stated in
the sources of reference"
Signature
Writer
Date
Rusmeyati binti Nordin
l APP. \ L 2 0 oS
llJ
First and foremost, I would like to express my deepest gratitude to my supervisor Mr.
Ho Yih Hwa for his supervision and invaluable guidance throughout this work.
I am most grateful to my lovely parents for being understanding and supportive in
whatever decision I made.
A special thanks to En. Mohd Razi bin Y aacob for his supported and En. Aini for his
k:ind.Jy assistance in providing all the necessary equipment in this project.
JV
ABSTRACT
Electromagnetic Levitation System had become a fast develop technologies
providing environmentally benefit solutions for industry and transportation. This project
is develop a Electromagnetic Levitation Demonstrator consist of two photo-detector and
one lifting coil. It is demonstrated how an electromagnetic can floating I pulls a steel ball
upward Wltil it interrupts a light beam that falJs on the photo-detector and how the coil
effect to electromagnetic levitation demonstrator but this system can only reach out a
few short centimeter and anything further might as well be infinity. This device need a
design and construct the circuit such as the coil driver and the different amplifier circuit,
Infrared emitter and Photo-detector ciicuit, the reference voltage and phase lead network
circuit and need to design the lifting coil
v
ABSTRAK
Sistem Pengapungan Elektromagnetik menjadi satu tecknologi yang berkembang
pesat dan menyediakan pelbagai faedah penyelesaian untuk industri dan pengangkutan.
Projek ini menunjukkan Sistem Pengapungan Elektromagnetik yang terdiri daripada dua
pengesan cahaya dan satu gegelung pengangkat Ia menunjukkan bagaimana
elektomagnetik tersebut boleh mengapungkan I menarik bebola Jogam naik ke atas
hingga biasan sinar cahaya terhadap pengesan cahaya yang akan menjatuhk:annya dan
bagaimana gegelung pengangkat akan memberi kesan kepada penunjuk
Sistem
Pengapungan Elektomagnetic ini. Sistem ini hanya boleh digunakan untuk jarak yang
.
pendek iaitu dalam beberapa sentimeter dan sebarang tambahan jarak seterusnya akan
menjadi ifiniti. Projek ini memerlukan rekaan dan susunan litar seperti litar pemacu
gelung, htar penguat pembezaan, litar pemancara inframerah, litar pengesan cahaya, litar
untuk voltan rujukan, litar penunjuk fasa dan memerlukan rekaan bagi gegelung
pengangkat.
Vl
CONTENT
CHAPTER
PAGE
TITLE
PROJECT TITLE
I
n
ACKNOWLEDGEMENT
11
DEDICATION
111
ABSTRACT
IV
ABSTRAK
v
CONTENT
VI
LIST OF TABLE
IX
LIST Of FIGURE
X
INTRODUCTION
l .l
Introduction
l
1.2
Project Objective
2
1.3
Scope Project
2
LITERATURE REVIEW
2.1
Introduction
3
2.1.1 Background of magnetic levitation
2.2.2
demonstrator
4
Electromagnetic Levitation
5
VI I
m
ELECTROMAGNETIC MODULE
3.1
Introduction
3.2
Flow Diagram of Electromagnetic
Levitation System
12
3.2.1
Input
12
3.2.2
Emitter
13
3.2.3
Signal Detector
14
3.2.4
Reference Detector
15
3.2.5
Difference AmpJifier
16
3.2.6
Loop Control
17
3.2.6.1 Benefit of Feedback
18
Loop Equations
19
3.2.7.1 Loop Gain
20
3.2.7.2 Transfer Function
21
3.2.8
Non Inverting Amplifier
22
3.2.9
Coil Driver
23
3.2.9.1 Specification for Lifting Coil
25
3.2.9.2 Coil Core
25
3.2.7
3.3
3.4
9
Power Supply
26
3.3.1 Coil Driver Supply
27
List of Component
28
3.4.1
Integrated Circuit IC LM741
30
3.4.2
Transistor NPN 2N3055
31
VlJJ
IV
RESIJLT
4.1
Introduction
33
4.1.1 Bode Plot of Phase Lead Network
33
4.2
Measurement
35
4.3
Design circuit at Printed Circuit Board
36
4.4
Casing
36
4.4.1 Material List
37
4.4
4.5
v
Electromagnetic levitation demonstrated
operation
38
How the Coil Wor1cs
39
DISCUSSION AND CONCLUSSION
5.1
Discussion
. 5.1.1
Winding Wire
41
41
5.1.2 Weight of the steel ball
42
5.2
Conclusion
42
5.3
Future Development
43
REFERENCE
45
APPENDIX
46
IX
LIST OF TABLE
NO.
TITLE
3.1
Voltage Requirements
3.2
List of Component and Equipment in
PAGE
27
Electromagnetic Levitation System
29
3.3
The Absolute Maximum Rating of LM741
31
3.4
Absolute Maximum Rating of Transistor
4.1
NPN2N3055
32
Material Jist
37
X
LIST OF FIGURE
NO
TITLE
2.1
An Electromagnetic
7
3.1(a)
Overall Process Flow
10
3.1(b)
Flow Process ofElectromagnetic Levitation System
11
3.2
Flow Diagram of Electromagnetic Levitation System 12
3.3
Emitter Circuit
13
3.4
Signal Detector circuit
14
3.5
Flow Diagram For Signal Detector to
.
PAGE
Voltage Follower
15
3.6
Reference Detector Circuit
15
3.7
Difference Amplifier Circuit
16
3.8
Feedback Control System
19
3.9
Transfer function Circuit
21
3.10
Non Inverting Amplifier circuit
22
3.11
Coil Driver Circuit
23
3.12
Transistor NPN 2N3055
24
3.13
Coil Core
26
3.14
Power Supply separated
28
3.15
Connection Diagram ofLM741
30
3.16
Internal Schematic Diagram of Transistor
4.1
NPN2N3055
32
Bode plot of Phase Lead Network
34
XI
4.2
Phase Lead Network Circuit
34
4.3
Signal and Reference Detector Measurement
35
4.4
Casing
37
4.5
Electromagnetic Levitation demonstrated
39
4.6
Coil Works
40
CHAPTER I
INTRODUCTION
1.1
INTRODUCflON
.
This thesis report on the design of the controller for keeping a steel ball
suspended in the air. In the ideal, the magnetic force produced by current from an
electromagnetic will counteract the weight of the steel ball. Nevertheless, the fixed
electromagnetic force is very sensitive, and there is noise that creates acceleration force
on the steel ball, causing the balJ to move into the unbalance region. The main function
of this controller is to maintain the balance between the magnetic force and the ball, s
weight According to the analytical method, the mathematical models of this magnetic
levitation system were established with the goal of designing the control system. System
linearization and phase lead composition were employed to design the controller of this
unstable nonlinear system. The algorithm proposed in this thesis provides a robust
closed-loop magnetic levitation system which can stabilize the system over a large range
of variations of the suspended mass. The design methods of this system are presented on
this thesis and the hardware is implemented for the scientific demonstration. Presented
in this thesis is about the magnetic levitation demonstrator which used two photo-
2
detector as a signal and reference, and a ljfting coil to produce magnetic field current to
pull a steel baH floating in the air.
1.2
PROJECT OBJECTIVE
The project objective is to demonstrated the concept of electromagnetic
levitation system by using two photo-detector and lifting coil and to produces the low
cost of electromagnetic levitation demonstrator. This electromagnetic levitation system
is selected and was build by follow their specification. The specification are to build a
magnetic coil which can produce an electromagnetic force carries with 2A of current,
and to definitely with Jess current the steel ball will move downward and when the high
current the steel baiJ will move upward
1.3
SCOPE PROJECT
This project built to studies and construct the emitter circuit, reference detector
circuit, photodetector circuit, different amplifier circuit, design the lifting coil, design the
signal detector circuit, design the non inverting amplifier circuit and design the phase
lead network circuit to demonstrate a steel ball float in the air.
CHAYrER
n
LITERATURE REVIEW
2.1
INTRODUCTION
This chapter discuss about how the steel ball can float in the air by using the
lifting coil and two photodetector which produce the magnetic force into this device.
The magnetic levitation demonstrator
is the simple structure an is based on
electromagnetic science by Sarnuel Earnshaw Theorem. In his theorem expressed the
perversity of inanimate of magnetic objects.
When we hold two permanent magnets close together, you see that one of them will
jump strongly toward from the other. It explains this frustrating behavior will
always prevent you from suspending otze permanent magnet above or below
another, no matter how one arranges the two magnets. However, an active control
circuit can get around this problem by rapidly adjusting the magnet's strength.
I 842. Samuel Earnshaw
4
The basic principles is to used a current to manipuJate electromagnetic power
which can counteract the weight of the steel ball and keep it suspended in the air.
2.1.1
BACKGROUND OF MAGNETIC LEVITATION DEMONSTRATOR
This magnetic levitation demonstrator is a technological advances in areas offer
the possibility of generating high electromagnetic fields with high efficiency. The
magnetic levitation was build to give the advance mode of surface high speed
transportation whereby a vehicles gliding above a guide way is suspended, guided and
propeJJed by magnetic force, which without the magnetic levitation the speed will be
slow, take a long time and high cost but with magnetic levitation. the speed become fast
and the time is Jess for example the Maglev trans-rapid Maglev is the short form for
magnetic levitation which
means the train will float at the guide way using the basic
principles of magnet to replace the old steel wheel and train tracks. Maglev trains float
on a cushion of air,
eliminating friction. This lack of friction and the trains
aerodynamic design allow the trains to reach unprecedented ground transportation speed
of more that 3 JOm ph. Besides that the magnetic levitation is a good technologies that
can reduce the pollution such as reduce air and highway congestion, air pollution and
petrolewn used.
5
2.1.2 ELECTROMAGNETIC LEVITATION
The electromagnetic system keeps a steel ball suspended in the air by countering
the balls weight with electromagnetic force which can be expressed as the dynamic
following formula in an upward direction according to Newton' s law.
F = mg
(2.1)
where m is the weight of the ball, g as a gravitational constant and F is the force produce
from electromagnetic coil. The magnetic field generated by current and calculated from
Ampere' s Law or Biot-Savart Law are characterized by magnetic field Band the unit is
in Testa. When the generated field pass through the magnetic materials which contribute
internal magnetic field, ambiguities can arise a part of the field from external current and
the materials. The magnetic ·field strength had defined as another magnetic field quantity
designated as H, and the relation ship is:
H = B / Jlo
(2.2)
and if the value of unambiguous designated the driving magnetic influence from extend
current in a material, independent of the material magnetic response. The relationship of
8 can be written in the equivalent form:
(2.3)
6
Hand M wiJI have the same units, amperes'/meter. The relationship in eq. (2.3) holds
for all material whether they are linear or not For linear materials, M in (Aim) depends
linearity on H such that
M = XmH
(2.4)
where Xm is a dimensionless quantity ( ratio of M to H ) called magnetic susceptibility
of the medium. It is more or less a measure of how susceptible or sensitive the material
is to a magnetic field Substituting eq. (2.4 ) into eq. (2.3) yields:
B = JJQ(J + Xm ) H = Jili
(2.5)
B = JJQ 14H
(2.6)
or
The quantity J.1 = JJo J.lr is called the permeability of the material and is measured in
henry's/meter, the henry is the unit of inductance and will be defined a little later. The
dimensionless quantity Jlr is the ratio of the permeability of a given material to that of
free space and is known as a relative permeability of the material and JJQ being the
magnetic free space permeability J.1o = 4n x l 0 -7. The magnetic force will produce the
electromagnetic flux for the magnetic circuit The magnetic force produce flux with I
which called as flux path.
H = IN II
(2.7)
7
/=27tr
for a circular path :
H=IN I 21tr
(2.8)
Force on magnetic material is the practical interest to determined the force that a
magnetic field exert on a piece of magnetic material in the field. This is useful in
electromechanical system such as electromagnetic levitation system. An electromagnet
made from iron of constant relative permeability as shown in Figure 2.1. The coil bas N
turn and carries a current I. with ignored the fringing, the magnetic field in the air gap is
the same as that in iron (
B1n = B2n ).
-I-
\
Ｍｾ＠
I I
---,
II
- tｾＭ I
1
l
ｾ ｝＠
I·
Figure 2.1: An Electromagnetic
To find the force between the two pieces of iron, the changed of total energy
were calculated that would result of the two pieces of magnetic circuit separated by a
differential displacement dl. The work required to effect the displacement is equal to the
changed the stored energy in the air gap ( assuming constant current ) that is :
-Fdl = dWm = 2 [ (1 I 2)( B2 ｉ ｾＩ＠
S dl]
(2.9)
8
where S is the cross-sectional area of a gap, the factor two accounts for the two air gaps.
And the negative sign indicates that the force acts to reduce the air gaps ( or that the
force is attractive). Thus
F = -2 ( B2 S / 2 J.1o)
(2.10)
The force is exerted on the lower piece and not and the cWTent-carrying upper piece
giving rise in to the field The tractive force across a single gap can be obtained from
eq.(2.10) as
(2 .11)
This equation can be used to calculated the forces in many types of devices including in
electromagnetic levitation system. The tractive pressure in ( N/m2 ) in a magnetic
surface is
(2.12)
Which is the same as the energy density Wm in the air gap
CHAPTERID
SYSTEM DESJGN
3.1
INTRODUCTION
.
This chapter explained about the overall process flow and construction to build
the electromagnetic levitation demonstrator in Figure 3.1(a) from start until progress the
fmal report, to design the circuit and to make sure the objectives of this project
successfully done. Figure 3. 1(b) show the flow process of electromagnetic levitation
system functioned and their specifications, This system used the looping system as phase
lead network to reduced the coil strength to allow the ball to go down but doesn't turn to
the coiJ until the ball is past the reference spot This system also used the transfer
function and looping feedback system.
10
Studies about tbe electromagnetic
background and idea modeling of the project
Collect the information of electromagnetic
levitation system such as information of
electromagnetic coil and photodetector
Design the flow diagram specification
module of Electromagnetic Levitation
Demonstrator
Testing and result of electromagnetic
levitation system including construct
discussion and conc1usion
Submitted the final report
Figure 3.l(a ): Overall Process Flow
11
Produces light beam and
carries 300mA cwrent.
ｾ＠
Transistor Q 1
received the signal
from infrared
emitter and carries
less current when
Q2 blocked
Transistor Q2
received the signal
from infrared
emitter and carries
high current when
QJ blocked
Consist of2 op-amp and
funftioned as voltage
fo1lower
Comparator
Phase lead network
Non Inverting Amplifier
received the signal :from
phase lead network
Coil Driver
produced the
electromagnetic
field
Figure 3.1( b ) : Flow Process of E1ectromagnetic Levitation System
12
3.2
FLOW DIAGRAM OF ELECTROMAGNETIC LEVITATION SYSTEM
'lin
Signal
(+)
Detector
Phase
Lead
Net-work
Different
Amplifier
ｾ＠
ｾ＠
Amplifier
Coil
ｖｯｾ＠
Figure 3.2: Flow Diagram of Electromagnetic Levitation With Looping Feedback
System
The flow diagram shoWn in Figure 3.2 explained about the process sequence for
electromagnetic levitation system which separated by eight stage start from input until
output. Each stage explained are :
3.2.1
INPUT
The type of the input voltage that used is direct current (DC). This
electromagnetic system used three input voltage for lifting coil and for integrated circuit