it is also use ful

1. A PAPER PRESENTATION ON

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UNWIRED CHARGING
TRULY WIRELESS WORLD
(AUTONOMOUS)
Presented By
V.ASHWINI D.MALLESWARAMMA
III-B-Tech, EEE III-B-Tech, EEE
JNTU COLLEGE OF Engg, JNTU COLLEGE OF Engg
Anantapur, Anantapur
Andhra Pradesh Andhra Pradesh
E-mail: Ashwinivanam@gmail.com E-mail: malliswari212@gmail.com
Ph.no-8099858086 ph.no-9640261495

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range of power by the technique used in
ABSTRACT: this concept called “power casting”. This
Yes, now we can forget wires technology uses radio frequency waves
even for charging. My mobile have been for carrying power.
switched off, my Laptop computer have The efficient mid-range power can be
no charging …….no such questions! transmitted to any device which uses that
Can we imagine the life without range of power by the technique used in
electrical wires? from now, answer to this concept called “eCoupling”. This
this question is yes. The methods technology uses electro magnetic
proposed in the present paper though coupling for carrying power.
utilizes contrasting technologies for wire Now a days there is a Rapid
less transmission of power namely development of autonomous electronics
‘power cast technology’ and ‘eCoupled like Laptops, Cell-phones, House-hold
technology’ are presented in the name of robots and all the above devices
“unwired charging”, Which will typically rely on chemical energy
facilitate to Transfer power without storage(Battery) .As they are becoming
using wires. daily needs to present generation,
The efficient low-range power can be Wireless energy transfer would be useful
transmitted to any device which uses that for many applications as above and they

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need low-range and mid-range energy. only by connecting the device to the
This is the main reason to prepare this supply through electrical Wires. More
concept. often it looks like snakes ……cables,
cables…..and more cables… as shown
INTRODUCTION:
In our day-to-day life we use laptop
computers, cell phones, digital cameras,
voice recorder, portable printer,
MP3players all plays a significant role.
But the major limitation is that they have
to be charged regularly which is possible
But this dream of wire less charging spare time to even think about them
might be possible very soon, by means seriously!
of technology explained below. Unless Radio frequencies are foundational for
this concept is not implemented we can’t most devices we use today right from
really call the world as really wire free TVs and radios to mobile phones. But
world. This is because although wireless we ever think of how powerful the radio
mantra is a old concept over the world frequencies are?
we still need electric wires and chemical The simple example that makes radio
batteries for purpose of charging and frequency identification (RFID) superior
transmitting power. to barcodes is that they can store more
TECHNOLOGY: data, they can be read and written to,
Power casting technology: they can be re-used etc., but what makes
The Basic Idea: all this possible? How is RFID chip able
If we walk a few meters from to survive on its own, woven into some
where we are standing now we will product or person, isolated from the rest
probably be cutting across at least a of civilization? It is because the chip is
dozen radio waves zipping invisibly able to charge itself through the radio
across our room that is how common waves transmitted by the transceiver
they are…. So common that we barely when reading or writing. Basically this is

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a simple example of the energy carrying nanometer from perfection may all soon
property of radio waves be a thing of the past.
The power cast wireless power platform
consists of a transmitter called ‘power
caster’ and a receiver called ‘power
harvester’. The ‘power caster’ can
double the effective range, compared to
normal RF transmitters and a power
harvester can harvest up to 70% of the
theoretical maximum power with in the
 Then why cannot RF (Radio range and convert it into dc current for
Frequency) be used to power devices? the device to use. The power harvester is
If we have a Base station that a chip about half the size of an ordinary
draws power from a power line and battery used for charging and must be
keeps transmitting it as radio waves and accompanied by a small antenna whose
all our mobile devices have receivers size varies according to the frequency of
that can receive these radio waves and transmitted power. It can fit quite
convert them into DC current, that’s comfortably into the battery
pretty much a wire less powering compartment of most devices, and many
system. That is one base station can devices could use the case itself as the
charge quite number of devices-provided antenna. Of course small tweaks in the
they all have the receivers built into circuitry of the device will be needed to
them this is precisely how the power cast connect the power harvester to it.
system works
TECHNOLOGY BEHIND THE The power harvester is available in
POWER: various models for multiple frequency
ranges, voltage requirements sizes and
The mess of wires, those power strips so on. The design can fully customized
overloaded with transformers and according to the requirements. Any
maddening gadget connectors half a device fitted with a power harvester gets
charged automatically whenever it is

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with in the range of power caster and Radio waves are in fact energy. They
any number of ‘power harvesting are already used to send and receive cell
devices’ can be placed within the range phone, television, radio, and ‘Wi-Fi’
of single power caster. This does not signals every day. Those waves spread
give rise to problems like cancellation out in all directions until they reach an
and interference because power caster antenna that is tuned to the appropriate
neither causes nor is affected by such frequency. Power cast's wireless power
problems. In-fact, the power harvesters platform uses a "Power caster"
actually outwit noises by making use of transmitter circuit running on
them. conventional current to broadcast a low-
power radio signal at a predetermined
POTENTIAL POWER
frequency. The smaller "Power
HARVESTERS:
harvester" receiver circuit which can be
embedded in any low-power device then
All the devices cannot be powered
uses that energy to recharge or can even
using power cast system only devices
replace the device's battery.
that work on AA, AAA batteries or cell
batteries can make use of this wire less
The Power cast solution is able to
power system. Power cast is designed to
maximize power transfer by using a
power devices with very low power.
much broader area of the RF spectrum,
Sensor networks, hearing aids, headsets
the 900-MHz band. While not
etc., are ideally suited for this
necessarily a replacement for a
technology basically any device which
conventional charger, the technology
requires small battery (to be recharged)
will be able to "trickle charge" a variety
are requires very little power for direct
of electronics over a period of time so
powering (such as Light Emitting Diode
that their energy is never fully depleted.
LED) is suitable for taking advantage of
power cast technology. Power cast As with a traditional AM/FM radio,
technology is designed to provide milli the closer one is to the tower
watts of power to devices with in an transmitting the signal, the better the
effective range of the transmitter. reception. Power cast's wireless platform
operates using a similar principle. The

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wireless power platform can harvest a regime of operation. If one can operate
few milli watts of energy within a meter in that regime in a given system, the
of the source, in this case the transmitter. energy transfer is expected to be very
That is enough energy to charge a single efficient. Midrange power transfer
depleted cell phone battery about half implemented in this way can be nearly
way overnight. The solution will also be omni directional and efficient,
ideal for devices with small batteries irrespective of the geometry of the
such as watches, hearing aids, wireless surrounding space, with low interference
keyboards and mice, and game and losses into environmental objects.
controllers, all of which could be The above considerations apply
continuously charged. But there are irrespective of the physical nature of the
limits to the charging capabilities the resonances.
Power cast platform. Larger devices
Magnetic resonances are
will not be able to make use of this
particularly suitable for everyday
‘power cast’ technology solution simply
applications because most of the
because they require too much power. In
common materials do not interact with
fact, the size limit for now seems to be at
Magnetic Fields, so interactions with
the cell phone level for effective
Environmental objects are suppressed
charging.
even further. We were able to identify
eCoupled technology: the strongly coupled regime in the
system of two coupled magnetic
The Basic Idea: resonances by exploring Non-radiative
The basic concept behind this is (near-field) magnetic resonant induction
Magnetic Resonance. Two resonant at Megahertz frequencies.
objects of the same resonant frequency
tend to exchange energy efficiently,
while dissipating relatively little energy
in extraneous off-resonant objects. In
systems of coupled resonances, there is
often a general “Strongly Coupled”

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Experimental Design:
Our experimental scheme
consists of two Self-resonant coils. One
coil (source coil) is coupled inductively
to an oscillating circuit; the other (device Efficiency of the System:
coil) is coupled inductively to a resistive
The efficiency of the system is
load. Self-resonant coils rely on the
nothing but the ratio of output power to
interplay between distributed inductance
input power. The output power is
and distributed capacitance to achieve
nothing but the device power rating and
resonance.
input power is sum of the power
The coils are made of an
dissipated by source, power loss due to
electrically conducting wire of total
decay and output power.
length ‘l’ and cross-sectional radius ‘a’,
Efficiency=Pw / (Ps+Pd+Pw)
wound into a helix of ‘n’ turns, radius
The experiment done in 7th June,
‘r’, and height ‘h’. There is no exact
2007 by the Massachusetts Institute of
solution for a finite helix in the
Technology, Cambridge gives the result
literature, and even in the case of
that in order to get 60W approximate
infinitely long coils, the solutions rely on
power is the output useful power with
assumptions that are inadequate for this
40% efficiency. They resonated the
system. So here the method implemented
circuit at ≈9.9 MHz so that they
is simple Quasi-static model to find the
developed the power is transmitted up to
parameters. Those are in Electro
8 times greater than the radius of the coil
Magnetic equations.
used.
ADVANTAGES OF ABOVE
TECHNOLOGIES:
• The need for batteries and
numerous redundant adaptors
which consists of toxic

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substances like nickel, cadmium, • As eCoupled technology is based
mercury are reduced. This on magnetic resonance it could
reduces the electronic waste. be easily effected by presence of
• There is no need for alkaline Ferro magnetic materials in its
batteries which are to be path.
recharged regularly. • In eCoupled technology as the
• Complexity and risk of electric device is close to the charging
shorts reduces as we are not source it is able to provide more
using any electrical wires. power than while charging using
• Unaffected by the day night RF.
cycle, weather or seasons. • Inductive method gives higher
• This is an eco friendly and the power at shorter distances but
system poses no health hazards power cast system though gives
what so ever as the power limits. low range power it transmits
• It is a boon for the devices which even at longer distances.
use low-range and mid-range • In eCoupled technology the
power resonance condition should be
COMPARISON BETWEEN ABOVE satisfied, if any medium error is
TECHNOLOGIES: there possibility of power
• Power cast technology is suitable transfer is affected, while as
for only low range power, while power cast system uses radio
eCoupled technology is suitable waves it is independent of
for both low-range and mid- medium around it.
range powers • In power cast technology any
• Power cast technology is number of power harvesting
effective even though the devices can be placed with in the
distance between transmitter and range of single power caster. It
receiver is high but major is not possible in case of
limitation of eCoupled eCoupled technology
technology is air gap should be CONCLUSION:
low.

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From the above discussion we can placed anywhere in the range of
conclude that no technology can be transmitter.
perfectly ideal by making use of best
ideas in the technologies and
working in conjunction with them
we can achieve wireless power
transmission very sooner. This
reduces the risk of using electrical
cables and redundant adaptors. Each
of the above system has its own pros
and cons and one needs to decide
based on one’s needs.
This is the Christmas tree which is
lighted based on power transmission
by radio frequency waves using
power cast technology. It can be