UNWIRED CHARGING USING POWER CAST TECHNOLOGY AND ECOUPLED TECHNOLOGY

A seminar report submitted to S.P.R. College of Engineering and Technology in Partial

Fulfillment of the Requirements for the award of

BACHELOR OF TECHNOLOGYIN

ELETRICAL & ELECTRONICS ENGINEERING

BY

S.MANOHAR REDDY Roll No: 08GM1A0225

Under the esteemed guidance of

R.NAGESWARA RAOAssistant Professor

DEPARTMENT OF ELECTRICAL ENGINEERING

S.P.R. COLLEGE OF ENGINEERING & TECHONOLOGY

(AFFILIATED TO JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY),

ANKUSHAPUR (VIL), GHATKESAR (MDL), RANGA REDDY (DIST).

2012

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DEPARTMENT OF ELECTRICAL ENGINEERING

S.P.R. COLLEGE OF ENGINEERING & TECHNOLOGY

(AFFILIATED TO JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY),ANKUSHAPUR (VIL), GHATKESAR (MDL), RANGA REDDY (DIST).

C E R T I F I C A T E

This is to certify that this technical seminar report entitled “unwired charging using powercast technology and ecoupled technology ” has been submitted by S MANOHAR REDDY bearing the Roll No: 08GM1A0225, in partial fulfillment of the requirements for the award of degree of Bachelor of Technology in Electrical & Electronics Engineering.

The result embodied in this project report has not been submitted to any other university/institution for the award of any degree.

Project Guide Head of Department

R.NAGESWARA RAO Md. Jaffar

Assistant Professor Assistant Professor

PRINCIPAL

P.Yadagiri

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ABSTRACT:

This paper consists It seems that these days everyone has a cellular phone. Whether

yours is for business

purposes or personal use, you need an efficient way of charging the battery in the phone.

My mobile have been switched off, my Laptop computer have no charging …….no such

questions! Can we imagine the life without electrical wires? from now, answer to this

question is yes. The methods proposed in the present paper though

utilizes contrasting technologies for wire less transmission of power namely ‘power cast

technology’ and ‘eCoupled technology’ are presented in the name of “unwired charging”,

Which will facilitate to Transfer power without using wires.

The efficient low-range power can be transmitted to any device which uses that range of

power by the technique used in this concept called “power casting”. This technology uses

radio frequency waves for carrying power.

The efficient mid-range power can be transmitted to any device which uses that range of

power by the technique used in this concept called “eCoupling”. This technology uses

electro magnetic coupling for carrying power.

Now a days there is a Rapid development of autonomous electronics like Laptops,

Cell-phones, House-hold robots and all the above devices typically rely on chemical

energy storage(Battery) .As they are becoming daily needs to present generation,

Wireless energy transfer would be useful for many applications as above and they need

low-range and mid-range energy. This is the main reason to prepare this concept.

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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 only by connecting

the device to the supply through electrical Wires. More often it looks like snakes ……

cables, cables…..and more cables… as shown

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But this dream of wire less charging might be possible very soon, by means of

technology explained below. Unless this concept is not implemented we can’t really

call the world as really wire free world. This is because although wireless mantra is a

old concept over the world we still need electric wires and chemical batteries for

purpose of charging and transmitting power.

TECHNOLOGY:

Power casting technology :

The Basic Idea:

If we walk a few meters from where we are standing now we will probably be

cutting across at least a dozen radio waves zipping invisibly across our room that is

how common they are…. So common that we barely spare time to even think about

them seriously!

Radio frequencies are foundational for most devices we use today right from TVs

and radios to mobile phones. But we ever think of how powerful the radio frequencies

are?

The simple example that makes radio frequency identification (RFID) superior to

barcodes is that they can store more data, they can be read and written to, they can be

re-used etc., but what makes all this possible? How is RFID chip able to survive on its

own, woven into some product or person, isolated from the rest of civilization? It is

because the chip is able to charge itself through the radio waves transmitted by the

transceiver when reading or writing. Basically this is a simple example of the energy

carrying property of radio waves

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Then why cannot RF (Radio Frequency) be used to power devices?

If we have a Base station that draws power from a power line and keeps

transmitting it as radio waves and all our mobile devices have receivers that can

receive these radio waves and convert them into DC current, that’s pretty much a wire

less powering system. That is one base station can charge quite number of devices-

provided they all have the receivers built into them this is precisely how the power

cast system works

TECHNOLOGY BEHIND THE POWER:

The mess of wires, those power strips overloaded with transformers and maddening

gadget connectors half a nanometer from perfection may all soon 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 range and convert it into dc

current for the device to use. The power harvester is a chip about half the size of an

ordinary battery used for charging and must be accompanied by a small antenna

whose size varies according to the frequency of transmitted power. It can fit quite

comfortably into the battery compartment of most devices, and many devices could

use the case itself as the antenna. Of course small tweaks in the circuitry of the device

will be needed to connect the power harvester to it.

The power harvester is available in various models for multiple frequency ranges,

voltage requirements sizes and so on. The design can fully customized according to

the requirements. Any device fitted with a power harvester gets charged automatically

whenever it is with in the range of power caster and any number of ‘power harvesting

devices’ can be placed within the range of single power caster. This does not give rise

to problems like cancellation and interference because power caster neither causes nor

is affected by such problems. In-fact, the power harvesters actually outwit noises by

making use of them.

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POTENTIAL POWER HARVESTERS:

All the devices cannot be powered using power cast system only devices that work

on AA, AAA batteries or cell batteries can make use of this wire less power system.

Power cast is designed to power devices with very low power. Sensor networks,

hearing aids, headsets etc., are ideally suited for this technology basically any device

which requires small battery (to be recharged) are requires very little power for direct

powering (such as Light Emitting Diode LED) is suitable for taking advantage of

power cast technology. Power cast technology is designed to provide milli watts of

power to devices with in an effective range of the transmitter.

Radio waves are in fact energy. They are already used to send and receive cell

phone, television, radio, and ‘Wi-Fi’ signals every day. Those waves spread out in all

directions until they reach an antenna that is tuned to the appropriate frequency.

Power cast's wireless power platform uses a "Power caster" transmitter circuit running

on conventional current to broadcast a low-power radio signal at a predetermined

frequency. The smaller "Power harvester" receiver circuit which can be embedded in

any low-power device then uses that energy to recharge or can even replace the

device's battery.

The Power cast solution is able to maximize power transfer by using a much

broader area of the RF spectrum, the 900-MHz band. While not necessarily a

replacement for a conventional charger, the technology will be able to "trickle charge"

a variety of electronics over a period of time so that their energy is never fully

depleted.

As with a traditional AM/FM radio, the closer one is to the tower transmitting the

signal, the better the reception. Power cast's wireless platform operates using a similar

principle. The wireless power platform can harvest a few milli watts of energy within

a meter of the source, in this case the transmitter. That is enough energy to charge a

single depleted cell phone battery about half way overnight. The solution will also be

ideal for devices with small batteries such as watches, hearing aids, wireless

keyboards and mice, and game controllers, all of which could be continuously

charged. But there are limits to the charging capabilities the Power cast platform.

Larger devices will not be able to make use of this ‘power cast’ technology solution

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simply because they require too much power. In fact, the size limit for now seems to

be at the cell phone level for effective charging.

eCoupled technology:

The Basic Idea:

The basic concept behind this is Magnetic Resonance. Two resonant 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” regime of operation. If one

can operate in that regime in a given system, the energy transfer is expected to be very

efficient. Midrange power transfer implemented in this way can be nearly omni

directional and efficient, irrespective of the geometry of the surrounding space, with

low interference and losses into environmental objects. The above considerations

apply irrespective of the physical nature of the resonances.

Magnetic resonances are particularly suitable for everyday applications

because most of the common materials do not interact with Magnetic Fields, so

interactions with Environmental objects are suppressed even further. We were able to

identify the strongly coupled regime in the system of two coupled magnetic

resonances by exploring Non-radiative (near-field) magnetic resonant induction at

Megahertz frequencies.

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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 coil) is coupled

inductively to a resistive load. Self-resonant coils rely on the interplay between

distributed inductance and distributed capacitance to achieve resonance.

The coils are made of an electrically conducting wire of total length ‘l’ and

cross-sectional radius ‘a’, wound into a helix of ‘n’ turns, radius ‘r’, and height ‘h’.

There is no exact solution for a finite helix in the literature, and even in the case of

infinitely long coils, the solutions rely on assumptions that are inadequate for this

system. So here the method implemented is simple Quasi-static model to find the

parameters. Those are in Electro Magnetic equations.

Efficiency of the System:

The efficiency of the system is nothing but the ratio of output power to input

power. The output power is nothing but the device power rating and input power is

sum of the power dissipated by source, power loss due to decay and output power.

Efficiency=Pw / (Ps+Pd+Pw)

The experiment done in 7th June, 2007 by the Massachusetts Institute of

Technology, Cambridge gives the result that in order to get 60W approximate power

is the output useful power with 40% efficiency. They resonated the circuit at ≈9.9

MHz so that they developed the power is transmitted up to 8 times greater than the

radius of the coil used.

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ADVANTAGES OF ABOVE TECHNOLOGIES:

The need for batteries and numerous redundant adaptors which consists of

toxic substances like nickel, cadmium, mercury are reduced. This reduces the

electronic waste.

There is no need for alkaline batteries which are to be recharged regularly.

Complexity and risk of electric shorts reduces as we are not using any

electrical wires.

Unaffected by the day night cycle, weather or seasons.

This is an eco friendly and the system poses no health hazards what so ever as

the power limits.

It is a boon for the devices which use low-range and mid-range power

COMPARISON BETWEEN ABOVE TECHNOLOGIES:

Power cast technology is suitable for only low range power, while eCoupled

technology is suitable for both low-range and mid-range powers

Power cast technology is effective even though the distance between

transmitter and receiver is high but major limitation of eCoupled technology is

air gap should be low.

As eCoupled technology is based on magnetic resonance it could be easily

effected by presence of Ferro magnetic materials in its path.

In eCoupled technology as the device is close to the charging source it is able

to provide more power than while charging using RF.

Inductive method gives higher power at shorter distances but power cast

system though gives low range power it transmits even at longer distances.

In eCoupled technology the resonance condition should be satisfied, if any

medium error is there possibility of power transfer is affected, while as power

cast system uses radio waves it is independent of medium around it.

In power cast technology any number of power harvesting devices can be

placed with in the range of single power caster. It is not possible in case of

eCoupled technology

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CONCLUSION:-

From the above discussion we can conclude that no technology can be 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 placed anywhere in the range

of transmitter.

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