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Seminar

on

WiTricity: Future of Electricity

Submitted to:

Mr. Abhinav Bansal

Assistant Professor

Department of ECE

Submitted by:

Hina Saxena

ECE-3rd year

Roll no.: 1103331064

Department of electronics & Communication



ontents

•What do you mean by WiTricity?

• Need of WiTricity

• History of Wireless power

• Experimental design of WiTricity technology

• WiTricity basics

• Wireless energy transfer techniques

• Working principle of WiTricity

• Is WiTricity safe?

• WiTricity Applications

• Benefits and Advantages

• Limitations

•References



What is WiTricity

• WiTricity is nothing but Wireless Electricity.

• Transmission of electrical energy from one object to

another without the use of wire is called WiTricity.

• Because of the wiTricity, some of the devices won’t

require batteries to operate.

Cables are going to be replaced by WiTricity



Why we need Witricity

•We use Wires..



And we use



Which sometimes ends as



Why not wires??

•

As per studies, most electrical energy transfer is through wires.

• Most of the energy loss is during transmission

• On an average, more than 30

•

In India, it exceeds by 40

Why not batteries??

Estimated that 40 billion batteries per year add to the e-waste burden.

And of course its not a good sign.



And this is possible due to

WIreless elecTRICITY

or WiTricity

Imagine your cell phones laptops i-pods and

other power hungry devices getting charged on

their own eliminating the need of plugging in.



History of Wireless power

In late 1890’s, Sir Nikola Tesla proposed the method ofwireless power transmission.

In 1899, he was able to light 200 lamps over 25 miles away

without using wires.

As it was in radiative mode, most of the power was wastedand less efficiency.

In 2005, Dave Gerding coined the term WiTricity which is

being used today.



Built the wardenclyffetower(Tesla tower) which couldbroadcast power wirelessly using

far-field techniques. Called off as

it radiated power intosurroundings raising issues of

power lossPower theft

Health concerns



The forgotten invention is reborn in

2007The idea of wireless

electricity has beenaround since the early

days of the Tesla coil.

But thanks to a group of MITscientists, "WiTricity" (as these

scientists call it) is now one

step closer to practical reality.

In 2007,6 MIT members headed

by Marin Soljacic were able tosuccessfully transmit power to abulb within a distance of 2m at a

freq of 9.9MHz .

They use concepts of nonradiative mid range energy

transfer, Resonance,

inductive coupling.

Efficiency at that point was

just approximately 43%.



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.



WiTricity Technology

Power source is connected to ac power.

Bulb is connected to capture device.

Blue lines represent the magnetic near field

induced by the power source.

Yellow lines represent the flow of energy from

the source to the capture coil.

This power lights up the bulb.

The magnetic field can wrap around the obstacle

between power source and capture coil.



asics of witricity



Fundamentals

• Electricity is a general term that

encompasses a variety of phenomena

resulting from the presence and flow of

electric charge.

•Magnetism

is a force that acts at adistance due to a magnetic field. This field

is caused by moving electrically charged

particles or is inherent in magnetic

objects such as magnet.



• Electromagnetic induction is the production of voltage across aconductor moving through a

magnetic field.• Electromagnetism is one of the four

fundamental interactions of nature,along with strong interaction, weak

interaction and gravitation. It is the force that causes the interactionbetween electrically charged particles;the areas in which this happens arecalled electromagnetic fields

•Energy/Power Coupling: Energy

coupling occurs when an energysource has a means of transferringenergy to another object.



• R esonance : It is the tendency of a

system to oscillate with larger

amplitude at some frequencies than at

others. These are known as the system'sresonant frequencies (or resonance

frequencies). At these frequencies, even

small periodic driving forces can

produce large amplitude oscillations.

• Resonant Magnetic Coupling: Magnetic

coupling occurs when two objects

exchange energy through their varyingor oscillating magnetic fields. Resonant

coupling occurs when the natural

frequencies of the two objects are

approximately the same.



Types of wireless energy transfer

techniques

Short range

Inductive

coupling

Mid range

Resonance

Inductive

coupling

Long range

Electromagnetic

Wave Power

Transfer



How does Inductive Coupling work??

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 is in proximity to a magnetic field, it

generates a current in that wire.”

Magnetic fields decay quickly , making inductive

coupling effective only at very short ranges.

• Wireless Charging Pad(WCP),electric brushes are

some examples

• On a WCP, the devices are to be kept, battery will

be automatically charged.



How does Resonant Induction work

•

Resonant induction still uses thesame principles as magnetic

induction (magnetic fields to

transfer current) , but it uses

resonance to increase the range

at which the transfer canefficiently take place.

• “Resonance", a phenomenon that

causes an object to vibrate whenenergy of a certain frequency is

applied.

WiTricity is based on Resonant Inductive coupling..



Long range: Far field power transfer

• Far-field method achieves longer ranges which is much

greater than the diameter of device.

•These far-field type techniques include Radio &

Microwave Power Transmission Techniques & LASER

Techniques.



ow WiTricity works

1) Power from mains to antenna, which is made of copper.

2) Antenna resonates at a frequency of 10MHz, emittingelectromagnetic waves.

3) 'Tails' of energy from antenna 'tunnel' up to 2.5m (8.2ft).

4) Electricity picked up by laptop's antenna, which must also beresonating at 10MHz. Energy used to re-charge device.

5)Energy not transferred to laptop re-absorbed by sourceantenna. People/other objects not affected as not resonating at

10MHz.





Efficiency Chart of WiTricity

It is observed that efficiency decreases with increase in distance between

source coil and load coil.



Is WiTricity Technology safe?

• WiTricity’s technology is a non-radiative mode of energytransfer, relying instead on themagnetic near field.

• Magnetic fields interact veryweakly with biologicalorganisms—people andanimals—and are scientificallyregarded to be safe.

• WiTricity products are beingdesigned to comply withapplicable safety standards andregulations.



WiTricity Applications

Consumer Electronics

• Automatic wireless charging of mobile electronics in home, cars, offices.

• Mobile phones, Laptops, Game controllers etc.

Industrial Applications

•

Direct wireless power and communication interconnections at points of use inharsh environments.

• In Drilling, Mining, Underwater etc.

Transportation

• Automatic wireless charging for existing electric vehicle classes.

• In Golf carts, Cars etc.

Other Applications( Medical devices, Military applications

and Robots)

http://e/Other%20Stuff/WPT/9.png

http://e/Other%20Stuff/WPT/9.png



Benefits of WiTricity

It will make products :

More Convenient: • -No manual recharging or changing batteries.• -Eliminate unsightly, unwieldy and costly power cords.

More Reliable: • -Never run out of battery power.• -Reduce product failure rates by fixing the ‘weakest link’: flexing wiring

and mechanical interconnects.

More Environmentally Friendly: • -Reduce use of disposable batteries.• -Use efficient electric ‘grid power’ directly instead of inefficient battery

Charging.



Advantages

• Safe, fairly efficient, good range

• Boon for the devices which uses midrange power

•No need of line of sight.

•No need of power cables and batteries.

• Magnetic fields interact weakly with biological masses

(humans), and energy is only transmitted between

resonating objects.



Limitations

• Transmissions possible only in few meters.

• ossibility of “energy theft”.

•Efficiency decreases with distance.

•The resonance condition should be satisfied and if any

error exists, there is no possibility of power transfer.



uture of Witricity

If we apply this idea to the whole city we might not have to use

any wired cable. Moreover in the future it would save the

material cost and

“WE CAN SAVE THE WORLD YEAH! ! ! ”



References

• www.wikipedia.com

• S. Sheik Mohammed, K. Ramasamy, T. Shanmuganantham,”Wireless power transmission – a next generation powertransmission system”, International Journal of ComputerApplications (0975 – 8887)

• An article published in the Science Magazine as “WirelessPower Transfer via Strongly coupled magnetic fields ”

• www.witricity.com • http://www.sciencedirect.com/science/journals

http://www.wikipedia.com/

http://www.witricity.com/

http://www.sciencedirect.com/science/journals

http://www.sciencedirect.com/science/journals

http://www.witricity.com/

http://www.wikipedia.com/



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