The document is a project report on wireless power transfer submitted by a group of 5 students for their Bachelor of Engineering degree. It describes the design, modelling, prototyping and testing of a circuit to demonstrate wireless power transfer through inductive coupling between transmitter and receiver coils. The report includes chapters on the working principle, circuit design and analysis using software, engineering economics, comparison with other wireless power transfer methods and conclusions.

1. GUJARAT TECHNOLOGICAL UNIVERSITY
Chandkheda, Ahmedabad
Affiliated
C. K. PITHAWALA COLLEGE OF ENGINEERING AND TECHNOLOGY
A
Project report on
WIRELESS POWER TRANSFER
Under subject of
DESIGN ENGINEERING
B.E. III, Semester-V
ELECTRONICS AND COMMUNICATION BRANCH
Submitted by: Group- 24(B-division)
Sr no. Name of student Enrollment no.
1. Ishita Surati 120090111112
2. Mohit Sarda 130090111052
3. Mohnish Lavania 130090111053
4. Hetvi Naik 130090111055
5. Priyanka Banshiwal 130090111070
Prof. Jayesh Jivarani
(faculty guide)
Dr. Ninad S. Bhatt
(Head of the Department)
Academic year 2015-2016

2. DECLARATION
We hereby declare that the project report for the project entitled “Wireless Power
Transfer” submitted in partial fulfilment for the Degree of Bachelor of
Engineering in Electronics and Communication Engineering to Gujarat
Technological University, Ahmedabad, is a bonafide record of the project work
carried out at C.K. Pithawala College of Engineering and Technology under the
supervision of Prof. Jayesh Jivarani and that no part of this report has been
directly copied from any students’ report or taken from any other source, without
providing the reference.
Sr no. Name of student Sign of the Student
1. Ishita Surati
2. Mohit Sarda
3. Mohnish Lavania
4. Hetvi Naik
5. Priyanka Banshiwal

3. CERTIFICATE
This is to certify that the dissertation entitled “Wireless PowerTransfer” has been
carried out by Ishita Surati(120090111112), Mohit Sarda(130090111052),
Mohnish Lavania(130090111053), Hetvi Naik(130090111055), Priyanka
Banshiwal(130090111070) under my guidance in the partial fulfilment of the
Degree of Bachelor of Engineering in Electronics and Communication (IV
semester) of Gujarat Technological University, Ahmedabad during the Academic
year 2014-2015.
Guide:
Prof. Jayesh Jivarani
Dr. Ninad S. Bhatt
(Head of the Department)

4. ACKNOWLEDGEMENT
We express our sincere gratitude to our project guide Prof. Jayesh Jivarani, dept.
of Electronics and Communication engineering, CKPCET, Surat for his
stimulating guidance, continuous encouragement and supervision throughout the
course of project work.
We would like to place on record our deep sense of gratitude to Dr. Ninad S.
Bhatt, Head of the Department, Electronics and Communication engineering,
CKPCET, Surat for his generous guidance, help and useful suggestion.
We also wish to extend our thanks to all the faculty and other colleagues for
attending our presentation and for their insightful comments and constructive
suggestion to improve the quality of this project.
We owe many thanks to all our classmates whose supporthelped us to solve our
problems.

5. ABSTRACT
One of the major issue in power system is the losses occurs during the
transmission and distribution ofelectrical power. The percentage ofloss ofpower
during transmission and distribution is approximated as 26%. The main reason
for power loss during transmission and distribution is the resistance ofwires used
for grid. According to the World Resources Institute (WRI), India’s electricity
grid has the highest transmission and distribution losses in the world – a
whopping 27%. Numbers published by various Indian government agencies put
that number at 30%, 40% and greater than 40%.
Nikola Tesla is known as the “Father of Wireless”. Nikola Tesla is the one who
first conceived the idea of Wireless PowerTransmission and demonstrated “the
transmission of electrical energy without wires" that depends upon electrical
conductivity as early as 1891.However it is only really in the last decade that the
technology has been harnessed to the point where it offers real, tangible benefits
to real world applications. Applications using resonant wireless
powertechnology have been mostnoticeable in the Consumer Electronics market
where wireless charging promises to deliver new levels of convenience for the
charging of millions of everyday devices.
(Wireless) Inductive Power Transfer or IPT involves the transmission of energy
from a power source to an electrical load, without connectors, across an air
gap. The basis of a wireless power system involves essentially two coils – a
transmitter and receiver coil. The transmitter coil is energized by alternating
current to generate a magnetic field, which in turn induces a current in the receiver
coil.

6. CHAPTER 1 : INTRODUCTION
What is Wireless Charging?
Wireless charging is essentially the transmission of an electrical current from a
power sourceto a receiving device without the use of a physical connection. The
electrical current is then used to charge or re-charge the battery of the receiving
device. In this circumstance the receiving device can be anything from a
smartphone or wearable, to a large industrial forklift.
How does wireless charging work?
Wireless charging is based on the principle of magnetic resonance or inductive
power transfer (IPT) – the process whereby electricity is transferred between two
objects through coils.
Steps:
1. Mains voltage is converted into high frequency alternating current (AC).
2. The alternating current (AC) is sent to the transmitter coilby the transmitter
circuit. The alternating current then induces a time varying magnetic
field in the transmitter coil.
3. Alternating current flowing within the transmitter coil induces a magnetic
field which extends to the receiver coil (when within a specified distance).
4. The magnetic field generates current within the receiver coil of the device.
The process whereby energy is transmitted between the transmitter and
receiver coil is also referred to as magnetic or resonant coupling and is
achieved by both coils resonating at the same frequency.

7. 5. Current flowing within the receiver coil is converted into direct current
(DC) by the receiver circuit, which can then be used to charge the battery.

8. CHAPTER 2: MODELLING AND ANALYSIS USING
SOFTWARE
We used MULTISIM to simulate the circuit.
In this circuit ‘Timer IC’ i.e. IC 555. It is working in astable state.
It is used to generate varying magnetic field in coupled inductors.
Two Mosfet IRFP250 are operated in push pull operation.

9. CHAPTER 3 :ENGINEERING ECONOMICS OF DESIGN
1. Need for separate chargers are eliminated.
2. All the components used are easily available at general stores at low prices.
3. WPT will provide us a wire free environment.
4. This will lead to a globally efficient and cheap transmission system.
5. The costofthe transmission and receiving power would lower for the daily
users and the large scale reduction of power tariff would be easily visible.
6. The loss of transmission will be decreased and the power could easily be
transferred to any place irrespective of the geographical situations.
7. Power failures minimization will become possible which are caused by
short circuit and faults.
8. . It will make the system more efficient and environment friendly system.
9. The natural disasters such as floods, earthquakes, landslides or tornados
would not become the reason for power cuts and damages to the system.
10.The usage of land for the instalment of the system would completely be
eliminated
DESIGN CALCULATION
As for now we want effective wireless power transfer within the range of 1m.
Thus we have used the coil as per follows:
Transmitter coil: 10mH
Receiver coil: 5mH
We have used IC7812 i.e. Regulator IC it will yield 12V dc as for the requirement
of the device.
IC555 is used and operated in astable mode.
Transistors used are MOSFET and they are operated in push pull mode.
It is used for producing varying magnetic field in the transmitter circuit due to
which the flux is cut and current is induced in the receiver coil.

10. CHAPTER 4: DESGIN FOR USE, REUSE AND
SUSTAINABILITY
If there’s one bit of transformational technology in the mobile world today, it is
wireless charging.
Frankly, I find wireless charging is far better. It might seem that the difference
between plugging a cable on your desk into your smartphone and removing it as
you leave has the same level of frustration as placing a smartphone on a charging
station and picking it up as you leave is minimal; but the difference in comfort,
speed, and usability is like night and day.
Wireless charging works on the principle of Electromagnetic Induction. Coils of
wire in the base station (the charging plate) create a magnetic field as the current
passes through. This field can induce an electrical current in an adjacent coil of
wire without actually touching it. If this wire is part of a battery charging
circuit, then you have wireless charging.
It’s not as efficient as a direct cable connection but wireless charging is around
60%-70% efficient and it is still recommend that booting a device is donethrough
a wired connection. But for day-to-day use, just lining up the coils and letting
electromagnetism do the rest is the simple value proposition at the heart of
wireless charging.
It’s worth noting that the lithium-ion chemistry used in smartphone batteries
happily copes with having short bursts of energy to charge them up – which is
exactly what wireless charging can provide as you lift your smartphone up from
the charging pad and replace it throughout the day
“Resonant” wireless charging
Greater transfer distances and higher efficiency can be achieved through
resonance – whereby the transmitter and receiver coils oscillate (or resonate) at
the same frequency.
This resonant frequency refers to the frequency at which an object naturally
vibrates or rings – like the way a tuning fork rings at a particular frequency and
can achieve their maximum amplitude.

11. CHAPTER 5: PROTOTYPING
5.1 VERSIONS
5.1.1 BASIC IDEA WITH SIMULATION
5.1.2 VERSION A.1
A normal circuit on breadboard and principle showing model
5.1.3 VERSION A.2
Circuit on PCB with inductor
Issue with inductor value
5.1.4 VERSION A.3
Inductor was replaced by coils and circuit was redesign
5.1.5 VERSION A.4
Circuit is modified consisting a Timer IC. Coils are used.

12. CHAPTER 6: TEST THE PROTOTYPE
We have tested the final prototype in environmental condition.
The circuit is totally working and the bulb glows within a range of 6cm.
CHAPTER 7: MEASURING INSTRUMENTS/TECHNIQUES
INSTRUMENT:
During this project we used Multi-meter formeasuring the voltage received at the
receiver coil.
To troubleshoot the circuit.
To check for faulty components.
TECHNIQUE:
To determine the number of turns in receiver coil and transmitter coil we used the
formula of calculation of inductance,
L= [d2n2]/[18d+40]
Where,
L=Inductance in micro henry
d=diameter of coil (in inches)
l=length of coil (in inches)
n=number of turns.

13. CHAPTER 8:COMPARISON OF EXISTING METHODS
WIRELESS POWER TRANSMISSION TECHNIQUES
Several methods have been explored for Witricity i.e. Wireless Power Transfer.
This section describes the different methods of wireless power transmission.
Various methods are discussed in detail in subsequent subsections.
WIRELESS POWER TRANSMISSION USING MICROWAVES
Microwave wireless power transmission is a wide range process in which long
distance electric power transmission becomes possible. This process uses the
microwave voltage source which emits the microwaves. The microwave source
acts as a transmitting antenna and a microwave receiver is attached with the load
which acts as receiving antenna. The received microwaves are then converted
back in to electrical energy through which the load is driven. Different parts of
the wireless power transmission through microwaves are briefed as following.
The microwave sourceantenna acts as transmitting antenna at the base station. It
uses the microwaves of high frequency ranging from 1GHz to 1000 GHz . There
are many types of microwaves source antennas each of which has its own
efficiency. Usually the slotted wave guide, micro strip patch and parabolic dish
antennas are used for this purpose . For high power applications the slotted
waveguide antennas are used because of their high efficiency. The microwave
receiving antenna is mounted at the load end and due to high frequency of
microwaves it could be used for large distance applications of wireless power
transmission. At the load end the microwaves are received by microwaves
receiving antenna and then the received microwaves are converted back into dc
power. The unit which receives microwaves and then converts back to the dc
power is called rectenna. The rectenna is mounted at the load end. A typical
rectifying antenna used to produce dc power from microwave energy is called
rectenna. . These are extensively used in microwave wireless power transmission
systems. As defined in , “simple rectenna consists ofa dipole antenna with an RF
diode connected across the dipole elements. The diode rectifies the AC current
induced in the antenna by the microwaves, to producedc power, which powers a
load connected across the diode.”

14. WIRELESS POWER TRANSMISSION USING LASER
The second technique is the wireless power transmission using laser beam which
acts as a source. The laser beam of high intensity is thrown from some specific
distance to the load end. Depending on the range and intensity of the beam this
method is used for small distance applications. This process is similar to the solar
cells photovoltaic generation which uses the solar energy of the sun light and
converts it into electricity. At the load end highly efficient photo voltaic cells are
used which receive the laser beam, energize laser light and finally convert light
energy in to electrical energy. Experiments have shown that the wireless power
transmission through laser beam is 50 percent efficient with respect to other
methods but by using advance technology oflaser photovoltaic cells receivers the
efficiency could be increased. Various stages of process are described as
following. The laser source transmits the laser beam through an efficient lens.
The lens is used to converge the beam of the laser to the specific place where the
receiver is present. The laser receiver consists of a series of highly efficient
photovoltaic cells which receives the laser beam and then convert them into
electrical energy. The load is attached with the photovoltaic cells which after
being energized through laser beam convert light energy of laser beam into
electrical energy.
WIRELESS POWER TRANSMISSION BY MAGNETIC RESONANCE
The mutual induction phenomena between two coils work on the principle that if
there is a continuous varying current passes through one coil produces the
magnetic field in the space around first coil called primary coil. As this varying
magnetic field interacts with the secondarycoil it produces an induced current in
the secondary coil. This is also called magnetic resonance between two coils
operating at a same resonance frequency.

15. Mutual Induction Process
The frequency at which the amplitude of the waves produced in the system is
maximum called resonance frequency. The resonance frequency is attained by
varying different parameters affecting the gain of voltage produced within the
coils . The phenomena of wireless power transmission using mutual induction
consist of primary and secondary coils which act as transmitting and receiving
antenna respectively.
Magnetic Resonance Method
A set of copper wires is used which acts as transmitting and receiving coil. The
number of turns of copper wires, resistance and diameter affects the mutual
induction between them . Important parameters of the system include: operating
frequency of signal generator or source, voltage of the source, diameter and
resistance of the coils and number of turns of coils. We use oscillator for
generation of a particular voltage signal at which we can get such a frequency
where the mutual induction will be maximum. Suchfrequency is called resonance
frequency. There are many types of oscillators. Voltage control oscillator is one

16. of them. The voltage control oscillator consist of some resistors , capacitors ,
inductors transistor and a varying voltage source joined together in a manner to
get the required voltage signal having some specified value of frequency where
the mutual induction between the coils would be maximum i.e at resonance
frequency. The amplifiers are used for the amplification of the voltage signal so
that a high power voltage signal should be fed to the primary coil acting as
transmitting antenna. There are many types of amplifiers like class A, B, and C
amplifiers each having its own properties. Normally parallel combination of
transistors is used in power amplifiers. As our load operates at direct current
because devices like cellular phones and laptops use direct current for the
charging purpose. So rectification is done at the load end. The rectification is
done through bridge rectifier.
COMPARISON OF WIRELESS POWER TRANSMISSION METHODS :
Methods presented in above subsections are compared briefly in this subsection.
Each and every method has its own advantages and disadvantages regarding cost,
range and health hazards.
Comparison of Different Methods

17. CHAPTER 9: CONCLUSION
We understood the principle ofWireless Power Transmission i.e. Electro-
magnetic induction and we glowed an LED using this concept.
We are looking forward to operate other devices using this fascinating concept.
GLOBAL SCOPE
Because of wireless power transmission we can foresee ourselves walking in our
home with phone in pocket, while simultaneously charging it. No need of a
charger or power pads. If advanced enough, soon we might not need utility poles
to transmit electricity to our homes. Plus we would not need to replace them in
the event of a natural disaster. This would drastically increase safety as well.

18. CHAPTER 7:CONCLUSION
We understood the principle ofWireless Power Transmission i.e. Electro-
magnetic induction and we glowed an LED using this concept.
We are looking forward to operate other devices using this fascinating concept.
GLOBAL SCOPE
Because of wireless power transmission we can foresee ourselves walking in our
home with phone in pocket, while simultaneously charging it. No need of a
charger or power pads. If advanced enough, soon we might not need utility poles
to transmit electricity to our homes. Plus we would not need to replace them in
the event of a natural disaster. This would drastically increase safety as well.
CHAPTER 10: VIDEO OF PROTOTYPE