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IMPEDANCE

MATCHING

METHOD

FOR

CONTACTLE

SS POW ER

FEEDINGO F

PORTABLE


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WiTricity is nothing but wireless transmission ofelectricity.Transmission of electricity without using

wires.On an average 40% of energy is lost duringtransmission via wires.


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Trillions are being invested mere in theinfrastructure around the world for putting upwires to get power.

Charging of modern appliances like laptops,mobiles have become cumbersome and oftenwe wish these to get self charged.


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What's the Principle behind WiTricity?WiTricity - Wireless Electricity

Consider two self resonating copper coils of sameresonating frequency with a diameter 20 inches each. One copperwire is connected to the power source (WiTricity transmitter), whilethe other copper wire is connected to the device (WiTricity Receiver).

The electric power from the power source causes the copper coilconnected to it to start oscillating at a particular (MHz) frequency.Subsequently, the space around the copper coil gets filled withnonmagnetic radiations.

This generated magnetic field further transfers the power to theother copper coil connected to the receiver. Since this coil is also of

the same frequency, it starts oscillating at the same frequency as the first coil. This is known as 'coupled resonance' and is the principle behindWiTricity.


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HOW IT WORKS


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~Mutual induction

*Process of inducing emfin one coil due to varying flux inthe other coil nearby.

*Short range due tovairation in K with distance.

METHODS OF WIRELESS ENERGY TRANSFER


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COUPLED RESONANCE

Near field wireless transmission of electrical energy between two coilshaving high resonance at same frequency.

Transmission range is increased. No health danger.

Can send energy to multiple devices. The distance over which energy can transferred can be extended throughthe use of WiTricity High-Q resonant repeaters.


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in the case of electromagnetic radiation closer to visible region of spectrum power can be transmitted byconverting electricity into a laser beam that is then pointed at a solar cell receiver. This mechanism isgenerally known as "power beaming" because the power is beamed at a receiver that can convert it tousable electrical energy.

But effeciency is poor.
http://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Laser


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Microwave transmission refers to the technology of transmitting information or power by the useof radiowaves whose wavelengths are conveniently measured in small numbers of centimeters.

A rectenna is used to convert microwave back to electricity. Power beaming using microwaves has been proposed for the transmission of energy from orbiting solar

power satellites to Earth and the beaming of power to spacecraft leaving orbit has been considered.

But it is harmful to humans since it operates in far field.


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GAP=100MM GAP=250MM

FREQUENCY CHARACTERISTICS OF MAGNETIC RESONANT COUPLING

The efficiency vs frequency graph


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SPECIFIC DATA OF TEST PRODUCT COILS


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Load characteristics

Result of load characteristics


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Feeding image on experiment


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FEEDING EXPERIMENT


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WHAT ABOUT SAFETYNON RADIATIVE POWER TRANSFER

MAGNETIC FIELDS ARE SAFE FOR PEOPLE

AND ANIMALS

HIGHLY RESONANT COUPLING

MINIMIZES ENERGYTRANSFER TO AN OFF-RESONANT OBJECT


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SAFE FOR HUMANS?


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Witricity Corporation develops wireless

components for mobiles, laptops etc. Power pads introduced on which devices can rest

and receive charge.


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Transmission range not too long. Possibility of energy theft.

Cost of implementation high. Limited amount of power.


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WiTricity will definitely change the world we live. WiTricity has greater possibilities for

transmitting power with negligible losses and withease .

It will have major impact on many marketsegments and product designand simplify

human interface with infrastructure.


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REFERENCES:1.) Ota ,Y ; Takura , T ; Sato , F . Matsuki , H:Sato , T ; Nonaka Impedance matching method about multiple contactless power feedingsystem for portable electronic devices , IEEE transactions onmagnetics,vol.47,no.10,October 2011.2.) P . E . Glaser, Power from the Sin : Itsfuture,Science,vol.162,no.3856,pp.857 -861,1968.

3.) A . Kurs , A . Karalis , R .Moffatt , J.D.Joannopoulos,P.Fisher,and M.Soljacic , Wireless power transfer via strongly coupled magneticresonances,Science,vol.317,pp.83 -86,2007.4.) J.Miyamori,A.Haga,Y.Kakubari,F.Sato,H.Matsuki,andT.Sato,Examination of phase excitation in a desktop

CLPS,J.Magn.Soc.Japan,vol.33,no.2,pp.110 -113,2009.5.) T.Matsuzaki and H.Matsuki,Transcutaneous energy-transmitting coilsfor FES,J.Magn.Soc.Japan,vol.18,pp.663 -666,1994.


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