Development Of Wireless Power Transfer (WPT) Technology For Mini Aquarium Using Capacitive Power Transfer (CPT) Approach.
i
DEVELOPMENT OF WIRELESS POWER TRANSFER (WPT) TECHNOLOGY
FOR MINI AQUARIUM USING CAPACITIVE POWER TRANSFER (CPT)
APPROACH
LIYANA HAZWANI BINTI ZAMRI
This report is submitted in partial fulfilment of requirements for the Bachelor Degree
of Electronics Engineering (Industrial Electronics)
Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer
Universiti Teknikal Malaysia Melaka
June 2016
v
To Allah and everyone who contributes towards this journey especially my parents.
vi
ACKNOWLEDGEMENT
Firstly, I would like to say Alhamdulillah because without His will, I would
not able to finish my final year project on the expected date in good condition. I would
also like to say my thanks towards my parents, Mr. Zamri Bin Hashim and Mrs.
Rosmawati Binti Selamat for supporting my studies physically and mentally while
completing my study in this degree. Then, I want to express my gratitude towards my
supervisor, Dr. Mohd Shakir bin Md Saat for supervising my project as well as my
friends under his supervision that are Nor Mazidah, Muhammad Zulfikri, and Chu Soo
Hui who went through difficulties together in completing the project. I would also like
to say my thanks towards Phd. students and Master students under Dr. Shakir who
have lent their hands in assisting to complete the project. Finally yet importantly, I
would like to give my gratitude to lecturers, technicians, classmates, housemates, and
friends who I have known and helped in completing this project until the end.
Hopefully, the kindness these people have given to me will be rewarded by Allah.
vii
ABSTRACT
Since long time ago, electrical appliances in the aquarium use wired
technologies to power up the devices and this causes unpleasant view at power outlets
and risk for short circuit to be present in the water. To avoid those problems, Wireless
Power Transfer (WPT) technology using capacitive approach is applied on the
aquarium for this project as the main objective. The scopes of this project are that the
project is using Class E inverter due to better efficiency compare to other class
especially in wireless power transfer, 1MHz as operating frequency to transfer 1W of
power and the load used is LED strip with 12V input. Once the system is developed,
the system performance is analysed and achieved 72.6% efficiency in term of distance
and 23.6% efficiency for plate misalignment with fixed distance that is 2mm, acrylic
thickness. In the end, the WPT system is successful to be applied in the aquarium using
capacitive approach as well as there are potentials for improvement so that the product
can be marketed to meet the consumers’ demand.
viii
ABSTRAK
Sejak dahulu lagi, barangan elektrik di dalam akuarium menggunakan
teknologi wayar untuk menghidupkannya sekaligus menjadikan pemandangan yang
tidak selesa di tempat plag dan wujud risiko untuk kejadian lintar pintas dalam air.
Bagi mengelakkan masalah tersebut, teknologi pemindahan kuasa tanpa wayar
menggunakan kaedah kapasitif telah diaplikasikan ke dalam akuarium telah menjadi
objektif utama dalam projek ini. Skop bagi projek ini adalah menggunakan Kelas E
inverter untuk mendapatkan kecekapan yang terbaik berbanding kelas-kelas yang lain,
1MHz sebagai frekuensi operasi untuk pemindahan kuasa 1W, dan beban yang
digunakan adalah lampu jalur LED dengan kemasukan 12V. Setelah sistem berjaya
dilaksanakan, prestasi sistem telah dianalis dan berjaya mendapatkan 72.6%
kecekapan bagi analisis jarak dan kecekapan 23.6% bagi analisis ketidakjajaran plat
dengan jarak yang tetap iaitu 2mm, ketebalan akrilik. Akhir sekali, sistem WPT ini
berjaya untuk diaplikasikan ke dalam akuarium menggunakan pendekatan kapasitif
dan mempunyai potensi untuk penambahbaikan supaya boleh dipasarkan dengan kadar
segera.
ix
TABLE OF CONTENTS
CHAPTER ITEM
I
PAGE
PROJECT TITLE
i
REPORT VERIFICATION FORM
ii
STUDENT’S DECLARATION
iii
SUPERVISOR’S DECLARATION
iv
DEDICATION
v
ACKNOWLEDGEMENT
vi
ABSTRACT
vii
ABSTRAK
viii
TABLE OF CONTENTS
ix
LIST OF TABLES
xii
LIST OF FIGURES
xiii
LIST OF ABBREVIATIONS
xv
LIST OF APPENDIXES
xvi
INTRODUCTION
1
1.1 PROJECT BACKGROUND
1
1.2 PROJECT OBJECTIVES
2
1.3 PROBLEM STATEMENT
3
1.4 SCOPE OF PROJECT
3
1.5 OVERVIEW OF METHODOLOGY
4
1.6 PROJECT OUTLINE
5
x
II
LITERATURE REVIEW
6
2.1 LITERATURE OVERVIEW
6
2.2 WIRELESS POWER TRANSFER
8
2.2.1 Near Field WPT
9
2.2.1.1 Inductive Power Transfer (IPT)
10
2.2.1.2 Acoustic Power Transfer (APT)
13
2.2.1.3 Capacitive Power Transfer (CPT)
14
2.2.2 Far Field WPT
16
2.2.2.1 Microwave Power Transfer (MPT)
17
2.2.2.2 Laser Power Transfer (LPT)
18
2.3 CLASS E ZERO VOLTAGE SWITCHING
19
INVERTER
2.3.1 Zero Voltage Switching (ZVS)
III
21
METHODOLOGY
23
3.1 OVERVIEW
23
3.2 PROCESS FLOW OF THE PROJECT
25
3.3 CLASS E INVERTER
26
3.4 SERIES CAPACITOR
29
3.5 RECEIVER CIRCUIT
30
3.6 CIRCUIT SIMULATION
31
3.7 HARDWARE REALIZATION
32
3.7.1 CLASS E Inverter Circuit
32
3.7.1.1 Choke inductor
32
3.7.1.2 Series inductor
33
3.7.1.3 Shunt capacitor
34
3.7.1.4 MOSFET
34
3.7.1.5 Load
35
3.7.2 Bootloader
35
xi
3.7.2.1 PIC18F4550
IV
V
36
3.7.3 MOSFET Driver
36
3.7.4 Transmitter and Receiver Plate
37
3.7.5 Receiver Circuit
38
3.6 FABRICATION PROCESS
39
3.7 PROTOTYPE CONSTRUCTION
42
RESULTS AND DISCUSSIONS
45
4.1 RESULTS
45
4.1.1 Simulation Result
45
4.1.2 Experimental Result
48
4.1.2.1 Distance analysis for CPT system
51
4.1.2.2 Misalignment analysis for CPT system
53
4.1.2.3 Prototype result
54
4.2 DISCUSSIONS
55
4.3 FINANCIAL EXPENSES
57
CONCLUSION AND RECOMMENDATIONS
58
5.1 CONCLUSION
58
5.2 RECOMMENDATIONS
60
REFERENCES
61
xii
LIST OF TABLES
ITEM
TITLE
PAGE
3.1
Parameters for the Class E inverter
29
4.1
System Efficiency versus Distance
51
4.2
System Efficiency versus Misalignment distance
53
4.3
Financial Expenses
57
xiii
LIST OF FIGURES
ITEM
TITLE
PAGE
1.1
Steps in completing the project
4
2.1
Block diagram of WPT
7
2.2
Samsung Charging Station and RAVPower Wireless Qi
10
Charging Pad
2.3
Simple concept of inductive
11
2.4
Block diagram of IPT
11
2.5
Architecture of APT
13
2.6
Architecture of CPT
15
2.7
Block diagram of MPT system
17
2.8
Class E ZVS inverter (a) Circuit (b) Equivalent circuit
20
2.9
Class E switching inverter for optimum operation
21
3.1
WPT system using CPT approach for mini aquarium
24
3.2
Flowchart of the project
25
3.3
(a) typical class E inverter (b) WPT Class E inverter
27
3.4
Receiver circuit
30
3.5
Circuit of Class E inverter in LTSPICEIV
31
3.6
Toroidal inductor through hole type
33
3.7
Radial type of inductor
33
3.8
Tantalum capacitor type
34
3.9
MOSFET IRF510 packaging and schematic symbol
34
3.10
Metal resistor type
35
xiv
3.11
PIC18F4550 IC
36
3.12
MOSFET driver TC442
36
3.13
MOSFET driver schematic circuit
37
3.14
Transmitter plate
37
3.15
Schematic circuit for receiver circuit
39
3.16
Fabrication design and 3D visualization of transmitter circuit
40
3.17
Fabrication design and 3D visualization of receiver circuit
41
3.18
Design layout for prototype in the aquarium
42
3.19
Enclosure box for receiver circuit
43
3.20
LED waterproof strip
43
3.21
Decorations for aquarium
44
3.22
Complete setup of WPT system in aquarium using capacitive
44
approach
4.1
Waveform at gate of MOSFET
46
4.2
Waveform at drain of MOSFET
46
4.3
Waveform of drain and gate of MOSFET
47
4.4
Waveform before going into rectifier
47
4.5
Waveform at gate MOSFET
48
4.6
Waveform of drain and gate MOSFET of Class E inverter
49
4.7
Waveform before rectified at the load
50
4.8
Graph of efficiency versus distance
52
4.9
Graph of efficiency versus misalignment distance
54
4.10
Final prototype of the system with fishes in the aquarium
55
xv
LIST OF ABBREVIATIONS
WPT
- Wireless Power Transfer
IPT
- Inductive Power Transfer
CPT
- Capacitive Power Transfer
APT
- Acoustic Power Transfer
MPT
- Microwave Power Transfer
LPT
- Light Power Transfer
ZVS
- Zero Voltage Switching
DC
- Direct Current
MOSFET - Metal Oxide Semiconductor Field Effect Transistor
PWM
- Pulse Width Modulation
IC
- Integrated Circuit
xvi
LIST OF APPENDIXES
ITEM
TITLE
PAGE
A
Inductor 68uH
64
B
Inductor 120uH
65
C
Power MOSFET IRF510
67
D
Inductor toroidal type 1mH
73
E
Load resistor
74
F
Power Diodes UF4004
77
G
Coding for PIC18F4550
80
1
CHAPTER I
INTRODUCTION
The first chapter of this thesis explains about project background, project
objectives, problem statement of the project, scope of the project, overview of
methodology and lastly project outline.
1.1
Project Background
Electronic power transfer is commonly have connections between metal part
of plug and socket or commonly known as wired technology [1]. Currently, the
researchers in the world as well as manufacturers of electronics products are
attempting to replace the wired technology to wireless technology for power transfer
on electrical and electronics appliances. This is because the technology could lead to
better environment by reducing usage of non-renewable energy; i.e. petroleum for
2
mobile vehicles can be substitute with electrical vehicles. By having this technology,
cables and connectors, elimination in circuitry could be possible and thus increase
reliability and maintenance-free operation for critical field such as medical field and
military field. The advantages of WPT on cable elimination and maintenance free
operation are also helpful especially for underwater electronics devices to power up
aside common electronics devices that we use every day. .
Therefore, the classification of WPT is divided into two categories that are
near-field power transfer and far-field power transfer. In near-field power transfer, the
inductive power transfer (IPT) is the favourite power transfer type used for real world
applications compared to capacitive power transfer (CPT) and acoustic power transfer
(APT). Last year, IKEA has released a new product that is a small table that able to
charge electronics gadgets by placing the item at a certain spot and has introduced the
WPT technology to the consumers in worldwide and eliminate cable [2]. Besides IPT,
CPT and APT, microwave power transfer (MPT) and light power transfer (LPT) are
under the far-field power transfer category respectively [3]. For this project, WPT is
applied in the aquarium; using near field technique with CPT approach for WPT is
chosen. This is because CPT is capable to transmit through metal objects unlike IPT
and has higher efficiency than APT. Therefore, application of WPT in water for
instance, aquarium is interesting topic to be done because multiple devices are usually
used in the aquarium so the fishes can live comfortably although there are some
obstacles need to overcome to achieve perfect result.
1.2
Project objectives
The objectives of the project are:
1. To develop wireless power transfer (WPT) system using capacitive approach for
mini aquarium system.
2. To design Class E inverter as power converter to improve efficiency of such
system.
3. To analyse the performance of the developed system in term of output efficiency.
3
1.3
Problem statement
In order to raise fishes at home, an aquarium needs several electrical appliances
in the tank. To provide better environment for new habitat of these fishes, air pump,
water pump, and lights are some necessary electrical appliances used in the aquarium
[4]. Thus, this situation leads into presence of plug extensions use for power up
multiple devices as well as presence of a lot of wires that might cause unpleasant sight
and risk of short circuit. By having WPT technology replaces the wired technology,
the wires usage as well as power outlets can be reduced for these devices. Besides that,
cleaning the aquarium becomes less hassle if WPT is implemented to the aquarium.
Due to incapability of inductive approach to wirelessly transfer power through metal
shielding environment and acoustic approach to have lowest efficiency amongst the
near field approach, capacitive approach is selected to be the most suitable for WPT
system in the aquarium. Yet, the capacitive approach have issues need to be solved to
have a good performance in transferring power that are plate distance and
misalignment. So, the WPT implementation using capacitive approach in the aquarium
and the system performance are done for the project.
1.4
Scope of Project
The first scope of the project is having capacitive power transfer as the
approach for wireless power transfer. Next, Class E inverter is used as power converter
for the project. To represent a mini scale of usual aquarium, the size of aquarium that
is used for this project is 300mm x 210mm x 210mm. The required specification that
need to be fulfilled for the project are the operating frequency must be 1MHz, duty
cycle 50% because larger frequency causes parasitic capacitance value to be higher
while lower frequency causes the components value become larger and therefore
1MHz is an optimum frequency. As for the desired power output, 1W is used so that
4
power is capable to power up the load and each capacitor plate size used must be under
130mm width and 180mm length in order two plates can be placed as receiver of CPT
at the bottom of the aquarium. Finally, the distance between a pair of capacitor plate
is fixed to 2mm, which is the thickness of medium, acrylic.
1.5
Overview of Methodology
There are several processes are essential to be completed for this project to be
successful. The processes that are involved in the project are designing circuits
involved in prototype based on requirement desired by calculating component values
needed, simulate the circuits based on calculated values, testing the circuits using value
of components that nearest to successful simulate circuitry done, board fabrication and
assembling process , troubleshooting the circuits until the circuits function properly,
and lastly analyse the performance of the prototype by comparing to simulation result.
Figure 1.1 illustrates the steps in finishing the project.
Circuits design by calculating components value based on requirements desired.
Simulation of circuitry using LTspice, ISIS, or Multisim.
Circuitry testing on breadboard and prototype.
Board fabrication and assembling components on the circuits.
Troubleshooting circuits.
Performance and result analysis.
Figure 1.1 Steps in completing the project.
5
1.6
Project Outline
In Chapter I, the chapter introduces the project background, the problem
statement of the project, the objectives of the project, the scope of the project as well
as the project outlines. This chapter purposely gives the readers a clear view on the
purpose of the project and brief version of this thesis is all about.
Next, Chapter II is about literature review of the project. This chapter is
actually covers the previous works completed by other researchers. The previous
works done by the researchers includes wireless power transfer (WPT), inductive
power transfer (IPT), capacitive power transfer (CPT), acoustic power transfer (APT),
Class E inverter and zero voltage switching.
Chapter III describes thoroughly the methodology used in completing the
project and the process flow of the project. The approaches that are used for simulation
and completing the prototype part by part are well explained in this Chapter III.
Finally yet importantly, Chapter IV presents the result on simulation as well as
the experiment. The results obtained, later, discussed and analysed for the performance
done and the expenses for the project also presented briefly.
Finally, Chapter V deduces project conclusions based on the result achieved
and objectives desired. Recommendation on future works or improvements that can be
made for the project are also suggested as one of the part in the chapter.
6
CHAPTER II
LITERATURE REVIEW
For the second chapter, previous works and findings by other researchers that
are related to the project are reviewed and discussed. Background of Wireless Power
Transmission (WPT), structure of Inductive Power Transfer (IPT), Capacitive Power
Transfer (CPT), Acoustic Power Transfer (APT). Class E amplifier, Zero Voltage
Switching (ZVS) are thoroughly explained in this chapter.
2.1
Literature overview
WPT technology is technology that has been a hit trend in the past five years
among the researchers and developers and thus led to quite number of articles and
journals have been published in IEEE site [6-20]. In 1891, Nikola Tesla is one of the
earliest person who demonstrated the concept of this technology by powering
florescent lamps that is 25 miles away from power source without wires [5]. By
7
inventing rectenna that converts microwaves energy into DC current in early 1960s
and demonstrated the ability with powering up helicopter in 1964, author in [5] stated
that William C. Brown has also contributed in the development of wireless power
transmission through microwaves as medium.
For WPT technology to transfer smoothly from transmitter to receiver part,
there are several components need to be done. The block diagram of basic WPT system
is illustrated in Figure 2.1.
Power
Source
Inverter
Transmitter
medium
(Primary)
Receiver
medium
(Secondary)
Rectifier
Load
Figure 2.1 Block diagram of WPT
Based on Figure 2.1, direct current (DC) source from power source is converted
into AC by inverter circuit. Then, the converted power must be in AC form so that the
power can be transmitted from primary medium to secondary medium. Then, at
secondary medium, AC power will be converted to DC power by rectifier for load
usage such as electronic appliances i.e. mobile phones.
Generally, wireless power transfer can be classified into two categories; near
field WPT and far field WPT. These categorizations have considered three factors; 1.
The distance of transmission from the source, 2. The characteristics of the
electromagnetic field change and 3. Methods in achieving WPT. In this chapter, both
categories will be thoroughly explained to understand variety of WPT scheme.
8
Besides WPT, Class E inverter is also studied because the amplifier is chosen
as inverter circuit in this work. Class E amplifier is the power amplifier that has high
efficiency and simple structure that can be used in fast switching. S. Liu states that the
Class E circuit will have nearly 100% efficiency theoretically as the circuit satisfies
zero voltage switching (ZVS) condition and have fixed load [6]. Before ending the
second chapter, the condition of ZVS is explained entirely as the condition plays
significant role in achieving high efficiency.
2.2
Wireless Power Transfer (WPT)
A process of transmitting energy from one circuit onto another without passing
through any manmade conductive elements interconnecting them is known as WPT
[7]. By using WPT technology, several advantages, disadvantages, and challenges
should be known in using the system. Authors in [8] describe advantages and
disadvantages of WPT in their article in details.
One of advantages of WPT that is described in [8] is power transmission line
cables between source and consumers are eliminated in WPT. Not only the problem
with faulty cable or short circuit can be eliminated, the risk of electricity being stolen
also can be reduced. With elimination of cables, loss of transmission can be negligible
and therefore theoretically the efficiency is expected to be higher compared to wired
transmission. On top of that, the cost for power transmission and distribution will
become less and cost of electrical energy is reduced for consumer since no resistance
in wireless transmission. Furthermore, places that are impossible to reach with wired
transmission can easily be reached using WPT system. Lastly, the freedom in choosing
transmitter and receiver in the system is more varied for WPT system.
Even though there are many advantages of WPT system, every system must
have even slight drawback. The major drawbacks for the system are a very high capital
cost for practical implementation are needed for the system as well as probability of
external interference present when transferring power in the system.
DEVELOPMENT OF WIRELESS POWER TRANSFER (WPT) TECHNOLOGY
FOR MINI AQUARIUM USING CAPACITIVE POWER TRANSFER (CPT)
APPROACH
LIYANA HAZWANI BINTI ZAMRI
This report is submitted in partial fulfilment of requirements for the Bachelor Degree
of Electronics Engineering (Industrial Electronics)
Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer
Universiti Teknikal Malaysia Melaka
June 2016
v
To Allah and everyone who contributes towards this journey especially my parents.
vi
ACKNOWLEDGEMENT
Firstly, I would like to say Alhamdulillah because without His will, I would
not able to finish my final year project on the expected date in good condition. I would
also like to say my thanks towards my parents, Mr. Zamri Bin Hashim and Mrs.
Rosmawati Binti Selamat for supporting my studies physically and mentally while
completing my study in this degree. Then, I want to express my gratitude towards my
supervisor, Dr. Mohd Shakir bin Md Saat for supervising my project as well as my
friends under his supervision that are Nor Mazidah, Muhammad Zulfikri, and Chu Soo
Hui who went through difficulties together in completing the project. I would also like
to say my thanks towards Phd. students and Master students under Dr. Shakir who
have lent their hands in assisting to complete the project. Finally yet importantly, I
would like to give my gratitude to lecturers, technicians, classmates, housemates, and
friends who I have known and helped in completing this project until the end.
Hopefully, the kindness these people have given to me will be rewarded by Allah.
vii
ABSTRACT
Since long time ago, electrical appliances in the aquarium use wired
technologies to power up the devices and this causes unpleasant view at power outlets
and risk for short circuit to be present in the water. To avoid those problems, Wireless
Power Transfer (WPT) technology using capacitive approach is applied on the
aquarium for this project as the main objective. The scopes of this project are that the
project is using Class E inverter due to better efficiency compare to other class
especially in wireless power transfer, 1MHz as operating frequency to transfer 1W of
power and the load used is LED strip with 12V input. Once the system is developed,
the system performance is analysed and achieved 72.6% efficiency in term of distance
and 23.6% efficiency for plate misalignment with fixed distance that is 2mm, acrylic
thickness. In the end, the WPT system is successful to be applied in the aquarium using
capacitive approach as well as there are potentials for improvement so that the product
can be marketed to meet the consumers’ demand.
viii
ABSTRAK
Sejak dahulu lagi, barangan elektrik di dalam akuarium menggunakan
teknologi wayar untuk menghidupkannya sekaligus menjadikan pemandangan yang
tidak selesa di tempat plag dan wujud risiko untuk kejadian lintar pintas dalam air.
Bagi mengelakkan masalah tersebut, teknologi pemindahan kuasa tanpa wayar
menggunakan kaedah kapasitif telah diaplikasikan ke dalam akuarium telah menjadi
objektif utama dalam projek ini. Skop bagi projek ini adalah menggunakan Kelas E
inverter untuk mendapatkan kecekapan yang terbaik berbanding kelas-kelas yang lain,
1MHz sebagai frekuensi operasi untuk pemindahan kuasa 1W, dan beban yang
digunakan adalah lampu jalur LED dengan kemasukan 12V. Setelah sistem berjaya
dilaksanakan, prestasi sistem telah dianalis dan berjaya mendapatkan 72.6%
kecekapan bagi analisis jarak dan kecekapan 23.6% bagi analisis ketidakjajaran plat
dengan jarak yang tetap iaitu 2mm, ketebalan akrilik. Akhir sekali, sistem WPT ini
berjaya untuk diaplikasikan ke dalam akuarium menggunakan pendekatan kapasitif
dan mempunyai potensi untuk penambahbaikan supaya boleh dipasarkan dengan kadar
segera.
ix
TABLE OF CONTENTS
CHAPTER ITEM
I
PAGE
PROJECT TITLE
i
REPORT VERIFICATION FORM
ii
STUDENT’S DECLARATION
iii
SUPERVISOR’S DECLARATION
iv
DEDICATION
v
ACKNOWLEDGEMENT
vi
ABSTRACT
vii
ABSTRAK
viii
TABLE OF CONTENTS
ix
LIST OF TABLES
xii
LIST OF FIGURES
xiii
LIST OF ABBREVIATIONS
xv
LIST OF APPENDIXES
xvi
INTRODUCTION
1
1.1 PROJECT BACKGROUND
1
1.2 PROJECT OBJECTIVES
2
1.3 PROBLEM STATEMENT
3
1.4 SCOPE OF PROJECT
3
1.5 OVERVIEW OF METHODOLOGY
4
1.6 PROJECT OUTLINE
5
x
II
LITERATURE REVIEW
6
2.1 LITERATURE OVERVIEW
6
2.2 WIRELESS POWER TRANSFER
8
2.2.1 Near Field WPT
9
2.2.1.1 Inductive Power Transfer (IPT)
10
2.2.1.2 Acoustic Power Transfer (APT)
13
2.2.1.3 Capacitive Power Transfer (CPT)
14
2.2.2 Far Field WPT
16
2.2.2.1 Microwave Power Transfer (MPT)
17
2.2.2.2 Laser Power Transfer (LPT)
18
2.3 CLASS E ZERO VOLTAGE SWITCHING
19
INVERTER
2.3.1 Zero Voltage Switching (ZVS)
III
21
METHODOLOGY
23
3.1 OVERVIEW
23
3.2 PROCESS FLOW OF THE PROJECT
25
3.3 CLASS E INVERTER
26
3.4 SERIES CAPACITOR
29
3.5 RECEIVER CIRCUIT
30
3.6 CIRCUIT SIMULATION
31
3.7 HARDWARE REALIZATION
32
3.7.1 CLASS E Inverter Circuit
32
3.7.1.1 Choke inductor
32
3.7.1.2 Series inductor
33
3.7.1.3 Shunt capacitor
34
3.7.1.4 MOSFET
34
3.7.1.5 Load
35
3.7.2 Bootloader
35
xi
3.7.2.1 PIC18F4550
IV
V
36
3.7.3 MOSFET Driver
36
3.7.4 Transmitter and Receiver Plate
37
3.7.5 Receiver Circuit
38
3.6 FABRICATION PROCESS
39
3.7 PROTOTYPE CONSTRUCTION
42
RESULTS AND DISCUSSIONS
45
4.1 RESULTS
45
4.1.1 Simulation Result
45
4.1.2 Experimental Result
48
4.1.2.1 Distance analysis for CPT system
51
4.1.2.2 Misalignment analysis for CPT system
53
4.1.2.3 Prototype result
54
4.2 DISCUSSIONS
55
4.3 FINANCIAL EXPENSES
57
CONCLUSION AND RECOMMENDATIONS
58
5.1 CONCLUSION
58
5.2 RECOMMENDATIONS
60
REFERENCES
61
xii
LIST OF TABLES
ITEM
TITLE
PAGE
3.1
Parameters for the Class E inverter
29
4.1
System Efficiency versus Distance
51
4.2
System Efficiency versus Misalignment distance
53
4.3
Financial Expenses
57
xiii
LIST OF FIGURES
ITEM
TITLE
PAGE
1.1
Steps in completing the project
4
2.1
Block diagram of WPT
7
2.2
Samsung Charging Station and RAVPower Wireless Qi
10
Charging Pad
2.3
Simple concept of inductive
11
2.4
Block diagram of IPT
11
2.5
Architecture of APT
13
2.6
Architecture of CPT
15
2.7
Block diagram of MPT system
17
2.8
Class E ZVS inverter (a) Circuit (b) Equivalent circuit
20
2.9
Class E switching inverter for optimum operation
21
3.1
WPT system using CPT approach for mini aquarium
24
3.2
Flowchart of the project
25
3.3
(a) typical class E inverter (b) WPT Class E inverter
27
3.4
Receiver circuit
30
3.5
Circuit of Class E inverter in LTSPICEIV
31
3.6
Toroidal inductor through hole type
33
3.7
Radial type of inductor
33
3.8
Tantalum capacitor type
34
3.9
MOSFET IRF510 packaging and schematic symbol
34
3.10
Metal resistor type
35
xiv
3.11
PIC18F4550 IC
36
3.12
MOSFET driver TC442
36
3.13
MOSFET driver schematic circuit
37
3.14
Transmitter plate
37
3.15
Schematic circuit for receiver circuit
39
3.16
Fabrication design and 3D visualization of transmitter circuit
40
3.17
Fabrication design and 3D visualization of receiver circuit
41
3.18
Design layout for prototype in the aquarium
42
3.19
Enclosure box for receiver circuit
43
3.20
LED waterproof strip
43
3.21
Decorations for aquarium
44
3.22
Complete setup of WPT system in aquarium using capacitive
44
approach
4.1
Waveform at gate of MOSFET
46
4.2
Waveform at drain of MOSFET
46
4.3
Waveform of drain and gate of MOSFET
47
4.4
Waveform before going into rectifier
47
4.5
Waveform at gate MOSFET
48
4.6
Waveform of drain and gate MOSFET of Class E inverter
49
4.7
Waveform before rectified at the load
50
4.8
Graph of efficiency versus distance
52
4.9
Graph of efficiency versus misalignment distance
54
4.10
Final prototype of the system with fishes in the aquarium
55
xv
LIST OF ABBREVIATIONS
WPT
- Wireless Power Transfer
IPT
- Inductive Power Transfer
CPT
- Capacitive Power Transfer
APT
- Acoustic Power Transfer
MPT
- Microwave Power Transfer
LPT
- Light Power Transfer
ZVS
- Zero Voltage Switching
DC
- Direct Current
MOSFET - Metal Oxide Semiconductor Field Effect Transistor
PWM
- Pulse Width Modulation
IC
- Integrated Circuit
xvi
LIST OF APPENDIXES
ITEM
TITLE
PAGE
A
Inductor 68uH
64
B
Inductor 120uH
65
C
Power MOSFET IRF510
67
D
Inductor toroidal type 1mH
73
E
Load resistor
74
F
Power Diodes UF4004
77
G
Coding for PIC18F4550
80
1
CHAPTER I
INTRODUCTION
The first chapter of this thesis explains about project background, project
objectives, problem statement of the project, scope of the project, overview of
methodology and lastly project outline.
1.1
Project Background
Electronic power transfer is commonly have connections between metal part
of plug and socket or commonly known as wired technology [1]. Currently, the
researchers in the world as well as manufacturers of electronics products are
attempting to replace the wired technology to wireless technology for power transfer
on electrical and electronics appliances. This is because the technology could lead to
better environment by reducing usage of non-renewable energy; i.e. petroleum for
2
mobile vehicles can be substitute with electrical vehicles. By having this technology,
cables and connectors, elimination in circuitry could be possible and thus increase
reliability and maintenance-free operation for critical field such as medical field and
military field. The advantages of WPT on cable elimination and maintenance free
operation are also helpful especially for underwater electronics devices to power up
aside common electronics devices that we use every day. .
Therefore, the classification of WPT is divided into two categories that are
near-field power transfer and far-field power transfer. In near-field power transfer, the
inductive power transfer (IPT) is the favourite power transfer type used for real world
applications compared to capacitive power transfer (CPT) and acoustic power transfer
(APT). Last year, IKEA has released a new product that is a small table that able to
charge electronics gadgets by placing the item at a certain spot and has introduced the
WPT technology to the consumers in worldwide and eliminate cable [2]. Besides IPT,
CPT and APT, microwave power transfer (MPT) and light power transfer (LPT) are
under the far-field power transfer category respectively [3]. For this project, WPT is
applied in the aquarium; using near field technique with CPT approach for WPT is
chosen. This is because CPT is capable to transmit through metal objects unlike IPT
and has higher efficiency than APT. Therefore, application of WPT in water for
instance, aquarium is interesting topic to be done because multiple devices are usually
used in the aquarium so the fishes can live comfortably although there are some
obstacles need to overcome to achieve perfect result.
1.2
Project objectives
The objectives of the project are:
1. To develop wireless power transfer (WPT) system using capacitive approach for
mini aquarium system.
2. To design Class E inverter as power converter to improve efficiency of such
system.
3. To analyse the performance of the developed system in term of output efficiency.
3
1.3
Problem statement
In order to raise fishes at home, an aquarium needs several electrical appliances
in the tank. To provide better environment for new habitat of these fishes, air pump,
water pump, and lights are some necessary electrical appliances used in the aquarium
[4]. Thus, this situation leads into presence of plug extensions use for power up
multiple devices as well as presence of a lot of wires that might cause unpleasant sight
and risk of short circuit. By having WPT technology replaces the wired technology,
the wires usage as well as power outlets can be reduced for these devices. Besides that,
cleaning the aquarium becomes less hassle if WPT is implemented to the aquarium.
Due to incapability of inductive approach to wirelessly transfer power through metal
shielding environment and acoustic approach to have lowest efficiency amongst the
near field approach, capacitive approach is selected to be the most suitable for WPT
system in the aquarium. Yet, the capacitive approach have issues need to be solved to
have a good performance in transferring power that are plate distance and
misalignment. So, the WPT implementation using capacitive approach in the aquarium
and the system performance are done for the project.
1.4
Scope of Project
The first scope of the project is having capacitive power transfer as the
approach for wireless power transfer. Next, Class E inverter is used as power converter
for the project. To represent a mini scale of usual aquarium, the size of aquarium that
is used for this project is 300mm x 210mm x 210mm. The required specification that
need to be fulfilled for the project are the operating frequency must be 1MHz, duty
cycle 50% because larger frequency causes parasitic capacitance value to be higher
while lower frequency causes the components value become larger and therefore
1MHz is an optimum frequency. As for the desired power output, 1W is used so that
4
power is capable to power up the load and each capacitor plate size used must be under
130mm width and 180mm length in order two plates can be placed as receiver of CPT
at the bottom of the aquarium. Finally, the distance between a pair of capacitor plate
is fixed to 2mm, which is the thickness of medium, acrylic.
1.5
Overview of Methodology
There are several processes are essential to be completed for this project to be
successful. The processes that are involved in the project are designing circuits
involved in prototype based on requirement desired by calculating component values
needed, simulate the circuits based on calculated values, testing the circuits using value
of components that nearest to successful simulate circuitry done, board fabrication and
assembling process , troubleshooting the circuits until the circuits function properly,
and lastly analyse the performance of the prototype by comparing to simulation result.
Figure 1.1 illustrates the steps in finishing the project.
Circuits design by calculating components value based on requirements desired.
Simulation of circuitry using LTspice, ISIS, or Multisim.
Circuitry testing on breadboard and prototype.
Board fabrication and assembling components on the circuits.
Troubleshooting circuits.
Performance and result analysis.
Figure 1.1 Steps in completing the project.
5
1.6
Project Outline
In Chapter I, the chapter introduces the project background, the problem
statement of the project, the objectives of the project, the scope of the project as well
as the project outlines. This chapter purposely gives the readers a clear view on the
purpose of the project and brief version of this thesis is all about.
Next, Chapter II is about literature review of the project. This chapter is
actually covers the previous works completed by other researchers. The previous
works done by the researchers includes wireless power transfer (WPT), inductive
power transfer (IPT), capacitive power transfer (CPT), acoustic power transfer (APT),
Class E inverter and zero voltage switching.
Chapter III describes thoroughly the methodology used in completing the
project and the process flow of the project. The approaches that are used for simulation
and completing the prototype part by part are well explained in this Chapter III.
Finally yet importantly, Chapter IV presents the result on simulation as well as
the experiment. The results obtained, later, discussed and analysed for the performance
done and the expenses for the project also presented briefly.
Finally, Chapter V deduces project conclusions based on the result achieved
and objectives desired. Recommendation on future works or improvements that can be
made for the project are also suggested as one of the part in the chapter.
6
CHAPTER II
LITERATURE REVIEW
For the second chapter, previous works and findings by other researchers that
are related to the project are reviewed and discussed. Background of Wireless Power
Transmission (WPT), structure of Inductive Power Transfer (IPT), Capacitive Power
Transfer (CPT), Acoustic Power Transfer (APT). Class E amplifier, Zero Voltage
Switching (ZVS) are thoroughly explained in this chapter.
2.1
Literature overview
WPT technology is technology that has been a hit trend in the past five years
among the researchers and developers and thus led to quite number of articles and
journals have been published in IEEE site [6-20]. In 1891, Nikola Tesla is one of the
earliest person who demonstrated the concept of this technology by powering
florescent lamps that is 25 miles away from power source without wires [5]. By
7
inventing rectenna that converts microwaves energy into DC current in early 1960s
and demonstrated the ability with powering up helicopter in 1964, author in [5] stated
that William C. Brown has also contributed in the development of wireless power
transmission through microwaves as medium.
For WPT technology to transfer smoothly from transmitter to receiver part,
there are several components need to be done. The block diagram of basic WPT system
is illustrated in Figure 2.1.
Power
Source
Inverter
Transmitter
medium
(Primary)
Receiver
medium
(Secondary)
Rectifier
Load
Figure 2.1 Block diagram of WPT
Based on Figure 2.1, direct current (DC) source from power source is converted
into AC by inverter circuit. Then, the converted power must be in AC form so that the
power can be transmitted from primary medium to secondary medium. Then, at
secondary medium, AC power will be converted to DC power by rectifier for load
usage such as electronic appliances i.e. mobile phones.
Generally, wireless power transfer can be classified into two categories; near
field WPT and far field WPT. These categorizations have considered three factors; 1.
The distance of transmission from the source, 2. The characteristics of the
electromagnetic field change and 3. Methods in achieving WPT. In this chapter, both
categories will be thoroughly explained to understand variety of WPT scheme.
8
Besides WPT, Class E inverter is also studied because the amplifier is chosen
as inverter circuit in this work. Class E amplifier is the power amplifier that has high
efficiency and simple structure that can be used in fast switching. S. Liu states that the
Class E circuit will have nearly 100% efficiency theoretically as the circuit satisfies
zero voltage switching (ZVS) condition and have fixed load [6]. Before ending the
second chapter, the condition of ZVS is explained entirely as the condition plays
significant role in achieving high efficiency.
2.2
Wireless Power Transfer (WPT)
A process of transmitting energy from one circuit onto another without passing
through any manmade conductive elements interconnecting them is known as WPT
[7]. By using WPT technology, several advantages, disadvantages, and challenges
should be known in using the system. Authors in [8] describe advantages and
disadvantages of WPT in their article in details.
One of advantages of WPT that is described in [8] is power transmission line
cables between source and consumers are eliminated in WPT. Not only the problem
with faulty cable or short circuit can be eliminated, the risk of electricity being stolen
also can be reduced. With elimination of cables, loss of transmission can be negligible
and therefore theoretically the efficiency is expected to be higher compared to wired
transmission. On top of that, the cost for power transmission and distribution will
become less and cost of electrical energy is reduced for consumer since no resistance
in wireless transmission. Furthermore, places that are impossible to reach with wired
transmission can easily be reached using WPT system. Lastly, the freedom in choosing
transmitter and receiver in the system is more varied for WPT system.
Even though there are many advantages of WPT system, every system must
have even slight drawback. The major drawbacks for the system are a very high capital
cost for practical implementation are needed for the system as well as probability of
external interference present when transferring power in the system.