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ABSTRACT:
The technology used for wireless power
transmission is known as witricity. Wireless
power transmission is not a new idea,
Nikola Tesla proposed theories of wireless
power transmission in the late 1800s and
early 1900s. Tesla's work was impressive,
but it did not immediately lead to wide
spread practical methods for wireless power
transmission. Since then many researchers
have developed several techniques for
moving electricity over long distances
without wires. Some exist only as theories or
prototypes, but others are already in use. In
2006 researchers at Massachusetts Institute
of Technology led by Marine Soijacic
discovered an efficient way to transfer
power between coils separated by a few
meters. They have dubbed this technology as
witricity
.
Witricity is based upon coupled resonant
objects. Two resonant objects of the same
resonant frequency tend to exchange energy
efficiently, while not interchanging the
surroundings. The researchers demonstrate
the ability to transfer 60W with
approximately 40% efficiency over distance
in excess of 2 meters. Currently the project
is looking for power transmission in the
range of 100watts. As witricity is in the
development stage, lots of work is to be
done in improving the range of power
transmission and efficiency.
1.INTRODUCTION
what it can make peoples lives easier, it can
add a lot of clutter in the If we are
particularly organized and good with tie
wrap then also a few dusty power cord
tangles around our home. We have even had
to follow one particular cord through the
seemingly impossible snarl to the outlet
hoping that the plug pull will be the right
one. This is one of the downfalls of
Fig.1:wireless electricity
electricity. While it can make people's
process. For these reasons, scientists have
tried to develop methods of wireless power
transmission that could cut the clutter or
lead to clean sources of electricity. Wireless
power transmission is not a new idea. Many
researchers developed several methods for
wireless power transmission. But witricity is
a new technology used for wireless power
transmission. By the use of this technology
transmission of electrical energy to remote
objects without wires can be possible. The
inventors of witricity are the researchers
from Massachusetts Institute of
Technology(MIT).
Fig.2:Expermiment on witricity
They developed a new technology for
wireless electricity transmission and this is
based upon the coupled resonant objects. In
this resonant magnetic fields are used. So
the wastage of power is reduced. The system
consists of witricity transmitters and
receivers. The transmitters and receivers
contain magnetic loop antennas made of
copper coils and they are tuned to the same
frequency.
2.HISTORY
While Tesla was the first person to demonstrate
the practical possibilities of wireless power in
1899, today, commercially there is little more
than electric toothbrushes and charger mats
available, and in both technologies the
toothbrush, phone, and other small devices
need to be extremely close to their chargers.
Wireless power transmission as an
alternative to transmission line power
distribution (our current system of electric
power distribution) was first proposed and
demonstrated by Nikola Tesla. In 1899,
Tesla demonstrated wireless power
Fig.3:fluorescent lamp
transmission by powering a field of
fluorescent lamps located twenty-five miles
from their power source without using
wires. As impressive and forward thinking
as Tesla's work was, at that time is was
actually cheaper to build coppertransmission
lines rather than build the type of power
generators that Tesla's experiments required.
Tesla ran out of research funding and at that
time a practical and cost efficient method of
wireless power distribution could not be
2
develoThis team from MIT belonged to the
Department of Physics, Department of
Electrical Engineering and Computer
Science and the Institute for Soldier
Nanotechnologies. The members of this
team were Andre Kurs, Aristeidis Karalis,
Prof. Peter Fisher, Robert Moffatt and Prof.
John Joannopoulos. The leader of this team
of researchers was Prof. Marin Soljacic.
fig.3:MITteam
It was Prof. Marin Soljacic who provided the
inspiration for the experiment and
invention of witricity. It was while standing
in the kitchen one night, that on staring at
his mobile phone that he had thought it
would be nice if his mobile phone would
take care of its own charging instead of him
having to periodically charge it.
He then tried out his experiment using two
coils of copper, where one was connected
to a receiver, and the other to a transmitter.
With the help of these two coils of copper,
the inventors of witricity managed to
transmit power across seven feet through
the air to instantly light up a lightbulb.
Though witricity worked only distances up
till 9 feet at its inception, the inventors
believed that it was possible to charge a
battery that was located at a distance of a
few yards from the power source that was
connected to the receiving coil. They state
that it would be sufficient to place a source
in each room to provide power to the whole
house.
3.WiTricity Technology: The Basics
The experimental design consisted of two
copper coils, each a self-resonant system.
One of the coils, connected to an AC power
supply, was the resonant source. The other
coil, the resonant capture device, was
connected to a 60 watt light bulb. The power
source and capture device were suspended in
mid-air with nylon thread, at distances that
ranged from a few centimeters to over 2.5
meters (8.2 ft). Not only was the light bulb
illuminated, but the theoretical predictions
of high efficiency over distance were proven
experimentally.
By placing various objects between the
source and capture device, the team
demonstrated how the magnetic near field
3
can transfer power through certain materials
and around metallic obstacles.
Thus Prof. Soljačić’s dream of finding a
method to wirelessly connect mobile electric
devices to the existing electric grid was
realized. WiTricity Corp. was soon launched
to carry this technology forward from the
MIT laboratories to commercial production.
Fig.4:witricity technology
3.1:Electricity: The flow of electrons (current)
through a conductor (like a wire), or charges
through the atmosphere (like lightning). A
convenient way for energy to get from one
place to another place
3.2:Magnetism: A fundamental force of
nature, which causes certain types of
materials to attract or repel each other.
Permanent magnets, like the ones on your
refrigerator and the earth’s magnetic field,
are examples of objects having constant
magnetic fields.
Fig.5:magnetism
Oscillating magnetic fields vary with time,
and can be generated by alternating current
(AC) flowing on a wire. The strength,
direction, and extent of magnetic fields are
often represented and visualized by
drawings of the magnetic field lines.
3.3:Electromagnetism: A term for the
interdependence of time-varying electric and
magnetic fields. For example, it turns out that
an oscillating magnetic field produces an
electric field and an oscillating electric field
produces a magnetic field.
Fig.6:Electro magnetism
As electric current, I, flows in a wire, it gives rise
to a magnetic field, B, which wraps around the
4
wire. When the current reverses direction, the
magnetic field also reverses its direction.
3.4:Magnetic Induction: A loop or coil of
conductive material like copper, carrying an
alternating current (AC), is a very efficient
structure for generating or capturing a magnetic
field.If a conductive loop is connected to an AC
power source, it will generate an oscillating
magnetic field in the vicinity of the loop. A
second conducting loop, brought close enough
to the first, may “capture” some portion of that
oscillating magnetic field, which in turn,
generates or induces an electric current in the
second coil. The current generated in the
second coil may be used to power devices. This
type of electrical power transfer from one loop
or coil to another is well known and referred to
as magnetic induction. Some common examples
of devices based on magnetic induction are
electric transformers and electric generators.
Fig.7:Magnetic induction
3.5:Energy/Power Coupling: Energy
coupling occurs when an energy source has
a means of transferring energy to another
object. One simple example is a locomotive
pulling a train car—the mechanical coupling
between the two enables the locomotive to
pull the train, and overcome the forces of
friction and inertia that keep the train still—
and, the train moves. Magnetic coupling
occurs when the magnetic field of one
object
Fig.8:Energy/power coupling
interacts with a second object and induces
an electric current in or on that object. In
this way, electric energy can be transferred
from a power source to a powered device.
In contrast to the example of mechanical
coupling given for the train, magnetic
coupling does not require any physical
contact between the object generating the
energy and the object receiving or capturing
that energy.
3.6:Resonance: Resonance is a property
that exists in many different physical
5
systems. It can be thought of as the natural
frequency at which energy can most
efficiently be added to an oscillating system.
A playground swing is an example of an
oscillating system involving potential energy
and kinetic energy. The child swings back
and forth at a rate that is determined by the
length of the swing. The child can make the
swing go higher if she properly coordinates her
arm and leg action with the motion of the
swing. The swing is oscillating at its resonant
frequency and the simple movements of the
child efficiently transfer energy to the system.
Another example of resonance is the way in
which a singer can shatter a wine glass by
singing a single loud, clear note.
In this example, the wine glass is the resonant
oscillating system. Sound waves traveling
through the air are captured by the glass, and
the sound energy is converted to mechanical
vibrations of the glass itself. When the singer
hits the note that matches the resonant
frequency of the glass, the glass absorbs energy,
begins vibrating, and can eventually even
shatter. The resonant frequency of the glass
depends on the size, shape, thickness of the
glass, and how much wine is in it.
3.7:Resonant Magnetic Coupling: Magnetic
coupling occurs when two objects exchange
energy through their varying or oscillating
magnetic fields. Resonant coupling occurs when
the natural frequencies of the two objects are
approximately the same.
Fig.9:Rsonant magnetic coupling
4.WiTricity Technology:
WiTricity power sources and capture devices
are specially designed magnetic resonators that
efficiently transfer power over large distances
via the magnetic near-field. These proprietary
source and device designs and the electronic
systems that control them support efficient
energy transfer over distances that are many
times the size of the sources/devices
themselves.
Understanding how it works is a bit more
involved, but it doesn’t require an engineering
6
Fig.10:witricity technology
you play a The WiTricity power source, left, is
connected to AC power. The blue lines
represent the magnetic near field induced by
the power source. The yellow lines represent
the flow of energy from the source to the
WiTicity capture coil, which is shown powering
a light bulb. Note that this diagram also shows
how the magnetic field (blue lines) can wrap
around a conductive obstacle between the
power source and the capture device.
5:HOW IT WORKS
Wireless light: Researchers used magnetic
resonance coupling to power a 60-watt light
bulb. Tuned to the same frequency, two 60-
centimeter copper coils can transmit
electricity over a distance of two meters,
through the air and around an obstacle.
The researchers built two resonant copper
coils and hung them from the ceiling, about
two meters apart.
When they plugged one coil into the wall,
alternating current flowed through it,
Creating a magnetic field.
The second coil, tuned to the same
frequency and hooked to a light bulb,
reso¬nated with the magnetic field,
generating an electric current that lit up the
bulb--even with a thin wall between the
coils.
Fig:11:working of witricity
There are two important terms to explain how
wireless electricity works in, for example, an
electric toothbrush, it works by "inductive
coupling" and "electromagnetism". According to
the Wireless Power Consortium, "Wireless
charging, also known as inductive charging, is
based on a few simple principles. The
technology requires two coils: a transmitter and
a receiver. An alternating current is passed
through the transmitter coil, generating a
magnetic field. This in turn induces a voltage in
the receiver coil; this can be used to power a
mobile device or charge a battery."To explain
further, whenever you direct an electrical
current through a wire there is a natural
7
phenomena that occurs, that a circular
magnetic field is created around the wire. And if
you loop/coil that wire that wire's magnetic
field gets stronger. If you take a second coil of
wire that does not have an electrical current
passing through it, and place that coil within the
magnetic field of the first coil, the electric
current from the first coil will travel through the
magnetic field and started running through the
second coil, that's inductive coupling.In an
electric toothbrush, the charger is connected to
a wall outlet that sends an electric current to a
coiled wire inside the charger creating a
magnetic field. There is a second coil inside of
the toothbrush, when you place the toothbrush
inside of its cradle to be charged the electric
current passes through the magnetic field and
sends electricity to the coil inside the
toothbrush, that coil is connected to a battery
which gets charged.The power exchange
efficiency of some induction systems is
improved by utilizing resonant circuits. These
so-called resonantly enhanced induction
techniques are used in certain medical implants
and high-frequency RFIDs for example.
However, to the best of our knowledge,
WiTricity’s founding technical team was the first
to discover that by specially designing the
magnetic resonators, one could achieve strong
coupling and highly efficient energy exchange
over distances much larger than the size of the
resonator coils, distances very large compared
to traditional schemes.
object to vibrate when energy of a certain
frequency is applied. Two resonant objects
of the same frequency tend to couple very
strongly." Resonance can be seen in musical
instruments for example. "Whtune on one,
then another instrument with the same
acoustic resonance will pick up that tune, it
will visibly vibrate,"
Instead of using acoustic vibrations, system
exploits the resonance of electromagnetic
waves. Electromagnetic radiation includes
radio waves, infrared and X-rays. Typically,
systems that use electromagnetic radiation,
such as radio antennas, are not suitable for
the efficient transfer of energy because they
scatter energy in all directions, wasting large
amounts of it into free space.
To overcome this problem, the team
investigated a special class of "non-
radiative" objects with so-called "long-lived
resonances".
When energy is applied to these objects it
remains bound to them, rather than escaping
to space. "Tails" of energy, which can be
many metres long, flicker over the surface.
If another resonant object is brought with
the same frequency close enough to these
tails then it turns out that the energy can
8
tunnel from one object to another.
Hence, a simple copper antenna designed to
have long-lived resonance could transfer
energy to a laptop with its own antenna
resonating at the same frequency. The
computer would be truly wireless.
Any energy not diverted into a gadget or
appliance is simply reabsorbed. The systems
that are described would be able to transfer
energy over three to five metres.
6:WiTricity is More Than...
6.1:Traditional Magnetic Induction
At first glance, WiTricity’s technology for power
transfer appears to be traditional magnetic
induction, such as is used in power
transformers, where conductive coils transmit
power to each other wirelessly, over very short
distances. In a transformer, an electric current
running in a sending coil (or “primary winding”)
induces another current in a receiving coil (or
“secondary winding”). The two coils must be
very close together, and may even overlap, but
the coils do not make direct electrical contact
with each other. However, the efficiency of the
power exchange in traditional magnetic
induction systems drops by orders of magnitude
when the distance between the coils becomes
larger than their sizes. In addition to electric
transformers, other devices based on traditional
magnetic induction include rechargeable
electric toothbrushes, and inductive “charging
pads” which require that the object being
charged be placed directly on top of, or very
close to, the base or pad supplying the power.
The power exchange efficiency of some
induction systems is improved by utilizing
resonant circuits. These so-called resonantly
enhanced induction techniques are used in
certain medical implants and high-frequency
RFIDs for example. However, to the best of our
knowledge, WiTricity’s founding technical team
was the first to discover that by specially
designing the magnetic resonators, one could
achieve strong coupling and highly efficient
energy exchange over distances much larger
than the size of the resonator coils, distances
very large compared to traditional schemes.
In addition to electric transformers, other
devices based on traditional magnetic
induction include rechargeable electric
toothbrushes, and inductive “charging pads”
which require that the object being charged
be placed directly on top of, or very close to,
the base or pad supplying the power.The
power exchange efficiency of some
induction systems is improved by utilizing
resonant circuits. These so-called resonantly
enhanced induction techniques are used in
certain medical implants and high-frequency
RFIDs for example. However, to the best of
our knowledge, WiTricity’s founding
9
technical team was the first to discover that
by specially designing the magnetic
resonators, one could achieve strong
coupling and highly efficient energy
exchange over distances much larger than
the size of the resonator coils, distances very
large compared to traditional schemes.
Fig.12: An electric toothbrush
6.2:Radiative power transfer
A microwave oven utilizes microwave
radiation to cook food.
Fig.13: A microwave oven utilizes
microwave radiation to cook food.
WiTricity’s technology for power transfer is
non-radiative and relies on near-field
magnetic coupling. Many other techniques
for wireless power transfer rely on radiative
techniques, either broadcasted or narrow
beam (directed radiation) transmission of
radio, or light waves. Broadcasted radiation
of radio frequency energy is commonly used
for wireless information transfer because
information can be transmitted over a wide
area to multiple users. The power received
by each radio or wireless receiver is
miniscule, and must be amplified in a
receiving unit using an external power
supply. Because the vast majority of
radiated power is wasted into free space,
radio transmission is considered to be an
inefficient means of power transfer. Note
that while more energy can be supplied to
the receiver by “cranking up the power” of
the transmitters in these systems, such high
power levels may pose a safety hazard and
may interfere with other radio frequency
devices. “Directed radiation”, using highly
directional antennas, is another means of
using radio transmission to beam energy
from a source to a receiver. However,
directed radiation—in particular microwave
radiation—may interact strongly with living
organisms and certain metallic objects. Such
10
energy transfer methods may pose safety
hazards to people or objects that obstruct the
line-of-sight between the transmitter and
receiver. These limitations make directed
radio transmission impractical for delivering
substantial levels of wireless power in a
typical consumer, commercial, or industrial
application. In fact, defense researchers are
exploring the use of directed energy systems
to deliver lethal doses of power to targets in
space and on the battlefield
Fig.14: The June 5, 1975 NASA JPL
Goldstone
6.3
:MagneticResonanceImaging(MRI):
Fig.15: MRI machines
MRI machines use “magnetic resonance
imaging” to produce diagnostic images of soft
tissue.Many people assume that WiTricity’s
“Resonant Magnetic Coupling” must be similar
to magnetic resonance imaging (MRI)
technology, however, the technologies are
similar in name only. MRI is, as its name
suggests, a technology for using magnetism as a
basis for diagnostic imaging of soft tissue in the
human body. It utilizes a strong DC magnet to
orient the magnetic fields of atoms within
tissues, and radio frequency fields to
manipulate those atoms in a selective way, so
that tissues and structures can be imaged
clearly. The “resonance” referred to in “MRI”
refers to the resonance of atomic structures.
MRI is not considered to be a method for
wireless power transfer.
7:Features and benifits
11
7.1:Highly Resonant Strong Coupling
Provides High Efficiency Over Distance:
WiTricity's mode of wireless power transfer
is highly efficient over distances ranging
from centimeters to several meters. We
define efficiency as the amount of usable
electrical energy that is available to the
device being powered, divided by the
amount of energy that is drawn by the
WiTricity source. In many applications,
efficiency can exceed 90%. And WiTricity
sources only transfer energy when it is
needed. When a WiTricity powered device
no longer needs to capture additional
energy, the WiTricity power source will
automatically reduce its power consumption
to a power saving “idle” state. Contact
WiTricity to learn the efficiency and
distance ranges that can be achieved in your
applications.
Fig.16:Highly reasonating
coupling7.2:Energy Transfer via Magnetic
Near Field Can Penetrate and Wrap Around
Obstacles
The magnetic near field has several
properties that make it an excellent means of
transferring energy in a typical consumer,
commercial, or industrial environment.
Most common building and furnishing
materials, such as wood, gypsum wall board,
plastics, textiles, glass, brick, and concrete
are essentially “transparent” to magnetic
fields—enabling WiTricity technology to
efficiently transfer power through them. In
addition, the magnetic near field has the
ability to “wrap around” many metallic
obstacles that might otherwise block the
magnetic fields. WiTricity’s applications
engineering team will work with you to
address the materials and environmental
factors that may influence wireless energy
transfer in your application.
7.3:Non-Radiative Energy Transfer is
Safe for People and Animals
WiTricity’s technology is a non-radiative
mode of energy transfer, relying instead on
the magnetic near field. Magnetic fields
interact very weakly with biological
12
organisms—people and animals—and are
scientifically regarded to be safe. Professor
Sir John Pendry of Imperial College
London, a world renowned physicist,
explains: “The body really responds
strongly to electric fields, which is why you
can cook a chicken in a microwave. But it
doesn't respond to magnetic fields. As far as
we know the body has almost zero response
to magnetic fields in terms of the amount of
power it absorbs." Evidence of the safety of
magnetic fields is illustrated by the
widespread acceptance and safety of
household magnetic induction cooktops.
Through proprietary design of the WiTricity
source, electric fields are almost completely
contained within the source. This design
results in levels of electric and magnetic
fields which fall well within regulatory
guidelines. Thus WiTricity technology
doesn’t give rise to radio frequency
emissions that interfere with other electronic
devices, and is not a source of electric and
magnetic field levels that pose a risk to
people or animals. Limits for human
exposure to magnetic fields are set by
regulatory bodies such as the FCC, ICNIRP,
and are based on broad scientific and
medical consensus. WiTricity technology is
being developed to be fully compliant with
applicable regulations regarding magnetic
fields and electromagnetic radiation.
7.4:Scalable Design Enables Solutions from
milliwatts to Kilowatts
WiTricity systems can be designed to handle
a broad range of power levels. The benefits
of highly efficient energy transfer over
distance can be achieved at power levels
ranging from milliwatts to several kilowatts.
This enables WiTricity technology to be
used in applications as diverse as powering a
wireless mouse or keyboard (milliwatts) to
recharging an electric passenger vehicle
(kilowatts). WiTricity technology operates in
a “load following” mode, transferring only
as much energy as the powered device
requires.
7.5:Flexible Geometry Allows WiTricity
Devices to be Embedded Into OEM
Products
WiTricity technology is being designed so
that it can be easily embedded into a wide
variety of products and systems. The physics
of resonant magnetic coupling enables
WiTricity engineers to design power sources
and devices of varying shapes and sizes, to
match both the packaging requirements and
the power transfer requirements in a given
13
OEM application. WiTricity has designed
power capture devices compact enough to fit
into a cell phone.OEM application.
WiTricity has designed power capture
devices compact enough to fit into a cell
phone.
8:WiTricity Intellectual Property
WiTricity is exclusive licensee of MIT
patents for Wireless Energy Transfer. Our
founder, MIT professor Marin Soljačić, was
the leader of the MIT research team that
developed WiTricity technology. This
includes the MIT patents for highly resonant
magnetic coupling as well as many energy
transfer system improvements. Since the
original discovery, WiTricity Corporation
has filed for patents on dozens of its own
innovations, including improvements to the
technology, as well as a large number of
products and applications that use the
technology. The MIT and WiTricity patents
are available for licensing for interested
parties. Please contact us to discuss potential
licensing agreements.Below is a partial list
of our issued patents and pending patent
applications.
9:WiTricity Products
WiTricity’s wireless power transfer
technology can be applied in a wide variety
of applications and environments. The
ability of our technology to transfer power
safely, efficiently, and over distance can
improve products by making them more
convenient, reliable, and environmentally
friendly. WiTricity technology can be used
to provide:
9.1:Direct Wireless Power—when all the
power a device needs is provided wirelessly,
and no batteries are required. This mode is
for a device that is always used within range
of its WiTricity power source.
9.2:Automatic Wireless Charging—when
a device with rechargeable batteries charges
itself while still in use or at rest, without
requiring a power cord or battery
replacement. This mode is for a mobile
device that may be used both in and out of
range of its WiTricity power source.
WiTricity technology is designed to be
directly embedded in the products and
systems of Original Equipment
Manufacturers (OEM's). If your company is
an OEM, you may be interested in our
developement kits which will allow you to
evaluate and adapt WiTricity wireless power
14
transfer to your own products, or you may
prefer a custom engagement with our in-
house research and development
department. Either way, we encourage you
to contact us to discuss your application in
more detail.
If you are a consumer eager to purchase
products that are WiTricity enabled, please
check back later at our website to learn
about products that you can purchase with
WiTricity inside!
10:Applications
1. Automatic wireless charging of mobile
electronics (phones, laptops, game
controllers, etc.) in home, car, office,
Wi-Fi hotspots … while devices are in
use and mobile.
2. Direct wireless powering of
stationary devices (flat screen TV’s,
digital picture frames, home theater
accessories, wireless loud speakers,
etc.) … eliminating expensive
custom wiring, unsightly cables and
“wall-wart” power supplies.
3. Direct wireless powering of desktop
PC peripherals: wireless mouse,
keyboard, printer, speakers, display,
etc… eliminating disposable
Fig.17:Consumer electronics
10.1:Industrial
1. Direct wireless power and
communication interconnections
across rotating and moving “joints”
(robots, packaging machinery,
assembly machinery, machine tools)
… eliminating costly and failure-prone
wiring.
2. Direct wireless power and
communication interconnections at
points of use in harsh environments
(drilling, mining, underwater, etc.) …
where it is impractical or impossible
to run wires.
3. Direct wireless power for wireless
sensors and actuators, eliminating the
need for expensive power wiring or
battery replacement and disposal.
4. Automatic wireless charging for
mobile robots, automatic guided
vehicles, cordless tools and
instruments…eliminating complex
15
docking mechanisms, and labor
intensive manual recharging and
battery replacement.
Fig.18:Industrial things
10.2:Transportation
Automatic wireless charging forexisting
electric vehicle classes: golf carts, industrial
vehicles.
1. Automatic wireless charging for
future hybrid and all-electric
passenger and commercial vehicles,
at home, in parking garages, at fleet
depots, and at remote kiosks.
2. Direct wireless power
interconnections to replace costly
vehicle wiring harnesses and slip
rings.
Fig.19:Electrical vehicals
10.3:Other Applications
Direct wireless power
interconnections and automatic
wireless charging for implantable
medical devices (ventricular assist
devices, pacemaker, defibrilator,
etc.).
Automatic wireless charging and for
high tech military systems (battery
powered mobile devices, covert
sensors, unmanned mobile robots
and aircraft, etc.).
Direct wireless powering and
automatic wireless charging of smart
cards.
Direct wireless powering and
automatic wireless charging of
consumer appliances, mobile robots,
etc
Fig.20:Other applications
11:ADVANTAGES OF WITRICITY
16
1. No need of line of sight - In witricity
power transmission there is any ;
need of line of sight between transmitter and
receiver. That is power !
transmission can be possible if there is any
obstructions like wood,
metal, or other devices were placed in
between the transmitter and
receiver.
2. No need of power cables and batteries -
Witricity replaces the use of power cables
and batteries.
3. Does not interfere with radio waves
4. Wastage of power is small -
Electromagnetic waves would tunnel, they
would not propagate through air to be
absorbed or dissipated. So the
wastage is small.
5. Negative heaiih implications - By the use
of resonant coupling wave
lengths produced are far lower and thus
make it harmless.
6. Highly efficient than electromagnetic
induction - Electro magnetic induction
system can be used for wireless energy
transfer only if the primary and secondary
are in very close proximity. Resonant
induction system is one million times as
efficient as electro magnetic induction
system.
7. Less costly - The components of
transmitter and receivers are cheaper. So this
system is less costly.
12:DISADVANTAGES
1. Wireless power transmission can be
possible only in few meters.
2. Efficiency is only about 40%.
As witricity is in development stage, lot of
work is done for improving the efficiency
and distance between transmitter and
receiver.
13:COCLUSION:
Witricity is in development stage, lots of
work is to be done to use it for wireless
power applications. Currently the project is
looking for power transmission in the range
of 100w. Before the establishment of this
technology the detailed study must be done
to check whether it cause any harm on any
living beings.
14:Future of witricity
Modern science has now made it possible to
use electricity without having to plug in any
wires. This concept is called witricty which
seems to have a bright future in providing
wireless electricity.
Researchers developed witricity using
resonance where energy is transmitted
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between two copper coils that resonate at the
same frequency. Of these two coils, one is
the power transmitter and the other, the
receiver. The advantage of witricity is that
there is no need of having a line of sight. As
long as the object to be powered has a
source of wireless power, in its vicinity, the
appliacnce charges automatically without
having to be plugged in.
Just imagine the future, with witricity, where
there will be no need of power cables and
batteries. The city just has to be covered
with witricity hot spots wherein you can use
your electric gadget battery and wire free
making it more convenient to carry around
and much lighter. With witricity, there will
be no need of charging batteries, or buying
new batteries for your electrical gadgets.
Just as beneficial witricity may be, there are
some contraindications to the concept, with
debates if it is risky living next to power
lines and having a low power witricity
network running in the home. They wonder
what happens if a glass of water is spilt in a
witricity room. However despite these
contraindications, witricity has a bright
future with the many advantages it provides
in terms of weight, convenience and
portability of electrical appliances.
REFERENCES
1.SasthraKeralammagazine
2.Witricitypower.com
.http://en.wikipedia.org
4.TreeHugger.com
5. http://www.howstuffworks.com
6.A radio transmitter can produce waves having a power of several kilowatts or even megawatts but this energy scatters in all directions. Only a small fraction, less than a millionth part, of the transmitted energy is received. However, this is sufficient to yield the intelligence.
7.^ Jump up to: a b G. A. Landis, "Applications for Space Power by Laser Transmission," SPIE Optics, Electro-optics & Laser Conference, Los Angeles CA, 24–28 January 1994; Laser Power Beaming, SPIE Proceedings Vol. 2121, 252–255.
8. ^ Jump up to: a b Corum, K. L. and J. F. Corum, "Nikola Tesla and the Diameter of the Earth: A Discussion of One of the Many Modes of Operation of the Wardenclyffe Tower," 1996
9.^ Jump up to: a b c d e f General Electric review, Volume 15 By General Electric. "Velocity of Propagation of Electric Field", Charles Proteus Steinmetz
10.Jump up ̂ 188,000 miles per second
11.Jump up ̂ Such as an internal change of load, starting and switching operations, and short circuits.
12.Jump up ̂ Such as the external change due to lightning.
13.Jump up ̂ Charles Steinmetz (Fellow, A. I. E. E. Chief Consulting Engineer, General Electric Company, Schenectady, N. Y.). "Condenser
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Discharge Through a General Gas Circuit". American Institute of Electrical Engineers., 1922. Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers. Presented at the 10th Midwinter Convention of the A. I. E. E., New York, N. Y., 15–17 February 1922.
11. Jump up ̂ viz., the dissipation of electric energy by the resistance of the conductor through its conversion into heat;
12. Jump up ̂ Such as when it gives trouble by induction in telephone circuits or when it reaches such high intensities as to puncture insulation, cause mechanical motion, etc.
13. Jump up ̂ such as an iron needle.
14. ^ Jump up to: a b c Theory and calculation of transient electric phenomena and oscillations By Charles Proteus Steinmetz
15.Jump up ̂ Speculation was made as to what
the electric wave was, leading to the
contradictory deductions that for certain
reasons space is considered as a gas of infinitely
low density, and for certain others as a solid.
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