Wireless power transfer with practical results in UNIVERSITY OF ESSEX final year Thesis MSc Electronic Engineering

1. WITRICITY WIRELESS POWER TRANSFER
Present By:
HAMZA MAJEED
2106193

2. INTRODUCTION
• Technology is always evolving in the world we live in. Every day, new innovations in technology help to simplify our
lives.
• Despite this, we continue to rely on the traditional wire system to charge our low power and even mid power
computers, digital cameras, and other everyday low power devices.
• When charging multiple devices at once, the traditional wire method becomes a tangle.
• Not to mention that each device has a charging connector with a unique design, it also consumes a lot of electrical
outlets.
• A question can come up at this point. What if these devices could all be charged simultaneously by a single device that
doesn't require any cords and doesn't make a mess?
• We examine it and came up with a suggestion.
• Inductive coupling, a straight forward and efficient method of wireless power transfer, offers a solution to all of these
problems.

3. WHAT WITRICITY IS?
• Witricity is a combination of the terms "wireless" and "electricity."
• This type of power transfer does not involve radiation. Radiative power transmission is used by the
majority of the other techniques.
• Witricity is unique because it makes use of magnetic coupling. A direct line of sight between the
transmitter and receiver is not required in this.
• Due to the friendly interaction of magnetic fields with living things, Witricity is also a risk-free method of
power transfer.
• These characteristics make Witricity a type of future technology that can be used to transmit electricity or
power between electrical sources and receivers without the usage of wires or cables.
• Witricity is different from normal magnetic induction, although looking similar.
• You can transfer power across a specific distance by keeping a few things in mind and making sure the
electromagnetic field is strong enough to support reliable power transmission.
• This is possible if the emitter and receiver both achieve magnetic resonance.

4. WHY WITRICITY?
• Think about a time when you could charge or
power your electronics without any wire.
• You may use cordless technology to charge or
power anything, including your lamp,
smartphone, and even television.
• This can be done by utilizing Witricity.
• The idea of wireless technology would have
been sneered at by scientists a century ago.
• But today we cannot picture living without
internet access and cell phones.

5. WORKING
• The alternating current's frequency is raised to its resonance frequency by the Witricity circuit's design.
• The inductor and capacitor loops, respectively, produce magnetic and electric fields that radiate outward
from the device for up to 5 meters.
• Any mobile device with an inductor loop and a receiver coil tuned to the same resonant frequency as this
magnetic field will experience an electric current.
• As a result, energy transfer is accomplished and both circuits resonate.

6. HISTORY
• Inductive power transfer between nearby wire coils was the earliest wireless power
technology to be developed, existing since the transformer was developed in the
1800s. Induction heating has been used since the early 1900s and is used for
induction cooking.
• In 1892 Maurice Hutin and Maurice Leblanc patented a wireless method of powering
railroad trains using resonant coils inductively coupled to a track wire at 3 kHz.
• In the early 1960s resonant inductive wireless energy transfer was used successfully
in implantable medical devices including such devices as pacemakers and artificial
hearts.
• The first passive RFID (Radio Frequency Identification) technologies were invented by
Mario Cardullo (1973) used in proximity cards and contactless smartcards.
• The Wireless Power Consortium was established in 2008 to develop interoperable
standards across manufacturers. Its Qi inductive power standard published in August
2009 enables high efficiency charging and powering of portable devices of up to 5
watts over distances of 4 cm.
• In 2007, a team led by Marin Soljačić at MIT used a dual resonance transmitter with
a 25 cm diameter secondary tuned to 10 MHz to transfer 60 W of power to a similar
dual resonance receiver over a distance of 2 meters.
• In 2008 the team of Greg Leyh and Mike Kennan of Nevada Lightning Lab used a
grounded dual resonance transmitter tuned to 60 kHz and a similar grounded dual
resonance receiver to transfer power over a distance of 12 meters

7. WIRELESS POWER TRANSMISSION TECHNIQUES
• Radiative and non-radiative approaches are the two broad groups into which WPT techniques can be
divided. The primary distinction between them is radiative approaches are RF-based while the other is
coupling-based.
• NEAR-FIELD-WPT
• INDUCTIVE COUPLING
• CAPACITIVE COUPLING
• MAGNETIC RESONANCE COUPLING
• (FAR-FIELD) WPT
• MICROWAVES WPT
• LASER- (WPT)
E
Magnetic
Resonance
Coupling

8. INDUCTIVE COUPLING
• Inductive coupling works on the principles of
electromagnetism.
• When a current (electricity) passes through a wire, it
generates a magnetic field perpendicular to the wire.
• When a wire close to this magnetic field, it generates a
current in that wire.
• Magnetic fields decay quickly, making inductive coupling
effective only at very short ranges.

9. CAPACITIVE COUPLING
• Capacitive coupling also referred to as electric coupling, makes
use of electric fields for the transmission of power between
two electrodes forming a capacitance for the transfer of power.
• In capacitive coupling energy is transmitted by electric fields
between electrodes such as metal plates.
• The transmitter and receiver electrodes form a capacitor, with
the intervening space as the dielectric.
• An alternating voltage generated by the transmitter is applied
to the transmitting plate, and the oscillating electric field
induces an alternating potential on the receiver plate by
electrostatic induction, which causes an alternating current to
flow in the load circuit.
• The amount of power transferred increases with the frequency

10. MAGNETIC RESONANCE COUPLING
• Magnetic Resonant coupling still uses the same principles as
magnetic induction(magnetic fields to transfer current)but it
uses resonance to increase the range at which the transfer can
efficiently take place.
• "Resonance", a phenomenon that causes an object to vibrate
when energy of a certain frequency is applied.
• Everything resonates at a certain frequency, based on its shape
and material.
• Two coils that resonate at the same frequency can transfer
power with a high efficiency since they are firmly linked.
• For the transmission to be as efficient as possible, the coupling
capacitors adjust the LC circuits of the transmitters and
receivers.

11. MICROWAVES WPT
• With a range of several kilometer's, (MWPT) is thought
to be the most effective far-field method for transferring
electricity.
• Raytheon introduced the first microwave WPT.
• A microwave generator converts direct current (DC) into
microwaves.
• It is isolated from the wave generator to prevent
detuning the selected frequency.
• The wave-guide adapter receives the microwaves via a
cable after that.

12. COMPENSATION NETWORK TOPOLOGIES
• The goal of capacitive correction is to remove the
imaginary part. This correction is needed for both the
primary and secondary circuits.
• As shown in Figure there are four topologies series-
series (SS), series-parallel (SP), parallel-series (PS), and
parallel-parallel (PP).
• To calculate compensated capacitances with regard to
various network topologies, reflected impedance
theory can be employed

13. IMPLIMENTATION
AND EXPERIMENTAL
RESULTS

14. Working with LED

15. Working with LED and Arduino

16. Observational result
• In this circuit I have 12 turns at primary side and its center tape to generate
maximum oscillation. On the other side secondary side have 10 turns to receive
power for load so the turn ratio is 1.2 for this circuit.so when I connect the input
at primary side and starting voltage is 5v DC given by DC power supply.
• when I put the secondary coil to primary coil and check the oscilloscope to see
the generated output so the distance where circuit start working is 10cm and
LED start glowing but the load I have is off because the voltage is not enough to
turn on the load because it needed 3.5 volt.
• So at next I have change the distance and coil become closer to each other’s now
when distance is become 7.5cm the load start Working. To glow an LED or some
LED’s this distance is fine to glow LED‘s but I have to turn on ARDUINO and it’s
operating voltage is minimum 3.5v.
• From all of my observation and experiments I have found a distance where
circuit is working at maximum efficiency and the distance is between 2.5cm to
5cm

17. MULTIPLE RECEIVERS WITH SINGLE TRANSMITTER.
• After this I have test Single transmitter and multiple
receivers
• At beginning it was not working but after some research I
realize that when we add capacitance on secondary and
primary side it’ll change the working distance and transfer
power from long distance.
• I have used three receiver and single transmitter coil for
the experimental purpose it was not working but when I
add capacitance in parallel with coil and after that it’ll start
working

18. Power Losses
• The majority of inductive coupling-based high-power wireless charging solutions contain system
efficiencies between 80 and 90%.
• Joule Heating:
It is a phenomena that happens whenever a wire or component has current flowing through it.
• Skin Effect:
When conductors are subjected to an alternating current. The "skin" of the conductor experiences
current flow as a result of this phenomena. The skin depth decreases with increasing frequency,
increasing resistance. As a result, the cable will heat up and experience additional joule losses.
• Switching Losses:
The switching loss is generated by MOSFET which required a particular time to switch the circuit on
and off which create loss in power transfer. Due to very fast switching produce heat in the circuit
which cost high internal impedance or sometime may increase the temperature of the circuit.
• Proximity Effect:
A phenomenon known as the proximity effect happens when two conductors through which an AC
current runs are close to one another. Eddy currents will form as a result, altering the current
density

19. Application
• Automobile Car
• Manufacturing Industry
• Military Equipment
• Medical Instrument
• Commercial electronic product

20. ADVANTAGES OF
WITRICITY
• No more messy wires.
• Witricity is consider as Safe.
• Automatic wireless charging.
• Direct wireless power.
• No manual recharging and changing
batteries.
• Ability to charge vehicles.
DISADVANTAGES OF
WITRICITY
• Mainly require short distances to
charge.
• Does not give enough energy to
power larger vehicles and
equipment.
• Cost.
• Still under production and
improvement.
• Less Efficiency compare to Wired
power transfer.