Contents
Declaration - - - - - - - - - - - - - - - - - - - - - - .. ii
Declaration of Originality - - - - - - - - - - - - - - - - - - ..iii
Dedication - - - - - - - - - - - - - - - - - - - - - - .. iv
Acknowledgement - - - - - - - - - - - - - - - - - - - - .. v
LIST OF TABLES - - - - - - - - - - - - - - - - - - - - .. viii
LIST OF FIGURES - - - - - - - - - - - - - - - - - - - - .. ix
Abstract - - - - - - - - - - - - - - - - - - - - - - - xi
List of Abbreviations - - - - - - - - - - - - - - - - - - - .. xii
CHAPTER 1: INTRODUCTION - - - - - - - - - - - - - - - - - 1
1.1Background - - - - - - - - - - - - - - - - - - - - - . 1
1.2 Problem Statement - - - - - - - - - - - - - - - - - - - . 1
1.3 Objectives - - - - - - - - - - - - - - - - - - - - - 2
1.3.1 Overall objective - - - - - - - - - - - - - - - - - - . 2
1.3.2 Specific objectives - - - - - - - - - - - - - - - - - - . 2
1.4 Justification for the Study - - - - - - - - - - - - - - - - - .. 2
1.5 Scope of work - - - - - - - - - - - - - - - - - - - - 3
1.6 Project Paper Organization - - - - - - - - - - - - - - - - - . 3
CHAPTER 2: LITERATURE REVIEW - - - - - - - - - - - - - - - . 5
2.1 Outline of the Chapter - - - - - - - - - - - - - - - - - - .. 5
2.2 History of Wireless Power Transfer - - - - - - - - - - - - - - .. 5
2.3 Main concepts of wireless transmission of electric energy - - - - - - - - - 6
2.4 Health and safety considerations - - - - - - - - - - - - - - - . 9
2.5 WPT Standards and Alliances - - - - - - - - - - - - - - - - 10
Qi by the Wireless Power Consortium (WPC) - - - - - - - - - - - - . 10
Rezence by the Alliance for Wireless Power (A4WP) - - - - - - - - - - . 10
Power Matters Alliance (PMA) - - - - - - - - - - - - - - - - 10
CHAPTER 3: THEORETICAL FRAMEWORK - - - - - - - - - - - - . 12
CHAPTER 4: METHODS AND MATERIALS - - - - - - - - - - - - .. 17
4.1 General Principle of Design - - - - - - - - - - - - - - - - 17
4.2Hardware and Software Components - - - - - - - - - - - - - - .. 20
4.2.1.1Power Supply - - - - - - - - - - - - - - - - - - .. 21
4.2.1.2DC - DC Boost Converter - - - - - - - - - - - - - - - 21
4.2.1.3 Royer Oscillator - - - - - - - - - - - - - - - - - - 22
4.2.1.4 Full Wave Bridge Rectifier - - - - - - - - - - - - - - - . 23
4.2.1.5 The Microcontroller Unit - - - - - - - - - - - - - - - . 25
4.2.1.6 The LCD Screen - - - - - - - - - - - - - - - - - .. 28
4.2.1.7 Switching Circuit - - - - - - - - - - - - - - - - - . 30
4.2.2 Software - - - - - - - - - - - - - - - - - - - - - 31
4.2.2.1USBasp - - - - - - - - - - - - - - - - - - - - .. 31
4.2.2.2 Programming Language - - - - - - - - - - - - - - - .. 32
CHAPTER 5: RESULTS AND DISCUSSIONS - - - - - - - - - - - - . 34
5.1 Results - - - - - - - - - - - - - - - - - - - - - - 34
5.2 Analysis and Discussion - - - - - - - - - - - - - - - - - .. 37
CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS - - - - - - - - 40
6.1 Conclusions - - - - - - - - - - - - - - - - - - - - . 40
6.2. Recommendations - - - - - - - - - - - - - - - - - - .. 41
REFERENCES - - - - - - - - - - - - - - - - - - - - - .. 42
APPENDICES - - - - - - - - - - - - - - - - - - - - - 43
CHAPTER 1: INTRODUCTION
1.1Background
If you are using an electronic device perhaps a mobile phone and you need to recharge the
battery then you will probably have to get a charger and connect the phone to the wire. But what
if you could charge it without having to connect it to wire? Meaning power will be transferred
wirelessly. This is possible through a concept called Wireless Power Transmission. Research and
studies have been done ever since the 19th century but it is only recently that this concept has
begun to be implemented.
Currently engineers are trying to discover how to increase the efficiency of power transmitted
wirelessly and also methods that that are safe to human beings and the environment and
notwithstanding, methods that are cheaper and hence can be commercially viable. Though still in
the early stages, several electronic companies are beginning to roll out devices that can
wirelessly transmit power.
Wireless power transmission (WPT) is based on the principle of electromagnetic induction.
Electromagnetic induction works on the concept of a primary coil generating a predominantly
magnetic field and a secondary coil being within that field so a current is induced within its coils.
This causes the relatively short range due to the amount of power required to produce an
electromagnetic field.
1.2 Problem Statement
The project seeks to eliminate the use of wires in the transmission of power from the source to
the device to be powered. Although WPT is based on electromagnetic induction, there are
various methods that are used. Some are less efficient than others and costly while others don’t
allow for a longer range of transmission. In this project, it is required to design and construct an
electronic device that shall transmit power within a small range. The device can then be used to
charge batteries for devices like pace makers.
In the project a suitable method will be used to ensure that enough power is transmitted
wirelessly so that it can then charge batteries. The major challenge will be in the coupling circuit
which comprises of the coils where electromagnetic induction occurs. The number of turns of the
coil, inductance
1.3 Objectives
The project has a main objective whose achievement is aided by breaking it further down into
other smaller specific objectives. This helps in showing comprehensively how the final objective
of the project is achieved in a clear and concise manner. 1.3.1 Overall objective
The main objective of the project is to develop a device for wireless power transfer
1.3.2 Specific objectives
The project will be divided into the following specific objectives that will aid in achieving the
main objective ï‚Â� Design and assemble a power supply unit. ï‚Â� Step up the dc supply. ï‚Â� Design and assemble an appropriate oscillator. ï‚Â� Develop transmitter and receiver coils. ï‚Â� Design the receiver module and rectify the ac voltage received on the receiver
coil. ï‚Â� Designing a battery charging circuit.
1.4 Justification for the Study
The need for devices that can wirelessly transmit power has over the years increased. Currently a
lot of research is being conducted in order to obtain suitable methods that can be used in the
development of such devices. The following are reasons why it is important
a) Flexibility: WPT will eliminate the use of conductors and wires. Rather than have
many wires running from a power source to power devices, the power can be
transmitted wirelessly hence the mess caused by cables can be avoided and also more
devices can be powered without having them all placed next to the power source
b) Safety: With the increase in electrification in areas, cases of electrical shocks have
been rampant as people and even animals end up touching the conductors. WPT will
eliminate these conductors hence preventing the electrical shocks.
c) Convenience: The application of WPT will enable the convenient use of devices. For
example, in the medical field pacemakers which use batteries can be recharged rather
than having a surgery every time the battery life is over. This will save on costs for
surgery and also is a more convenient option.
d) Reliability: Many times people are using a device and it runs out of power yet one
doesn’t have a cord to charge the device or perhaps there is no source of power
around. However with WPT the devices can be charged wirelessly hence the risk of
low battery power will be eliminated.
1.5 Scope of work
This project covers the hardware and software design and implementation of a device that will be
able to transfer power wirelessly. The study will look into the methods that are currently in use
and seek to improve on the areas where the performance is low. The hardware system will
involve the design and construction of a transmitter and receiver modules. Once there is proof
that power has been transmitted, a battery charging circuit will be designed and developed to
charge a 9V battery so as to show the application of a wireless power transfer device. The
software system will include code that will control ensure the system is intelligent enough to
determine the battery capacity and also to display the various parameters that are important.
1.6 Project Paper Organization
This project paper comprises five chapters namely: ï‚Â� Chapter 1:Introduction
This gives the project definition, project overview, objectives, project justification and
scope of work.
ï‚Â� Chapter 2: Literature Review
This chapter presents information on the evolution and present state of theory, practice
and research of wireless power transmission.
ï‚Â� Chapter 3: Theoretical Framework
In this chapter the theory behind the design of the project is given.
ï‚Â� Chapter 4: Methodology and Materials
This chapter gives a detailed explanation on how the device once assembled operates. It
also explains the components used and their role in the design of each part of the device.
ï‚Â� Chapter 5: Results and Analysis
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