WITRICITYOR

WIRELESS ELECTRICITYPresented By

Parikh Samarth J.Guided By

Mr. Nirav Patel

Agenda• What do you mean by Witricity!• How Witricity Works• The Experiment Conducted at MIT• Comparison with Traditional Technologies• Is Witricity a new Concept?• Pros & Cons• Advantages & Disadvantages• Applications• Conclusion

Witricity Enabled Room

• The Transfer of Electricity by resonant induction from one place to another without wires is known as “WiTricity”.

• On June 7 ’07, a team of researchers at MIT announced the successful operation of WiTricity concept.

• They had lit up a 60W bulb with a power source at a distance of 7 feet(over 2m) with no wires.

What do you mean by WiTricity!!!

Basic Working of Witricity

Working of Witricity

• Consider two self resonating copper coils of same resonating frequency with a diameter 20 inches each.

• One copper wire is connected to the power source (WiTricity Transmitter), while the other copper wire is connected to the device (WiTricity Receiver).

• The electric power from the power source causes the copper coil connected to it to start oscillating at a particular (MHz) frequency.

Working of Witricity

• Subsequently, the space around the copper coil gets filled with magnetic radiations.

• This generated magnetic field further transfers the power to the other copper coil connected to the receiver by means of magnetic induction.

• Since this coil is also of the same frequency, it starts oscillating at the same frequency as the first coil.

• This is known as ‘magnetically coupled resonance’ and is the principle behind WiTricity.

Working of Witricity

The Experiment

60W light-bulb being lit from 2m away

The Experiment

60W light-bulb being lit from 2m away & with an obstruction in the way

The Experiment

Team of Researchers at MIT who experimentally demonstrated transfer of electricity without wires!

• Graph between efficiency and distance[4].

• It shows that as the distance increases, the efficiency decreases.

Experiment Result

Comparision with Magnetic Induction

• In traditional magnetic induction the two coils must be very close together to transmit power wirelessly over very short distances.

• The efficiency of power exchange in this system drops considerably when the distance between coil becomes larger than their sizes .

• In witricity , one could achieve strong coupling and highly efficient energy extent over distances Much larger than resonator coils.

• Many wireless information broadcasting uses radiation of radio frequency energy.

• It is an inefficient means of power transfer because the vast majority of radiated power is wasted into free space.

• Witricity technology for power transfer is non-radiative and relies on near field magnetic coupling.

Comparision with Radiative Power Transfer

• No, this concept of wireless electricity is not new. In fact it dates back to the 19th century, when Nikola Tesla used conduction - based systems instead of resonance magnetic fields to transfer wireless power.

• Lasers have also been used to transmit energy without wires, but apart from requirement of uninterrupted line of sight (obstacles hinders the transmission process), it is also very dangerous.

• Also, radio waves are not feasible for power transmissions because the nature of the radiation is such that it spreads across the place, resulting into a large amount of radiations being wasted.

Is WiTricity a New Concept?

• What MIT team has done is that they have specifically tuned the transmitting unit to the receiving device.

• The transmission is also not hindered by the presence of any object in the line of sight.

• If the object to be charged is in the vicinity of the WiTricity source, then the energy transfer will undoubtedly take place.

• In this 'coupling resonance' system, the electric energy that is not used up by the receiver does not get radiated into the surrounding environment, but remains in the vicinity of the transmitter. This ensures safety as well as minimal wastage of power.

• One of the five researchers, Dr. Aristeidis Karalis says that their coupling resonance system is one million times more efficient as compared to old wireless power transmission techniques.

What is so Unique about Witricity?

ADVANTAGES OF WITRICITY• No need of line of sight i.e. it is

omnidirectional• Based on Magnetic resonances – any chances

of damage to human body is almost nil.

DISADVANTAGES OF WITRICITY• Wireless power transmission can be possible

only in few meters.• Efficiency achieved is only about 40% till now.

Applications• Automatic wireless charging of mobile electronics viz. phones,

laptops, game controllers, etc. while they are in use.• Direct wireless power connections at points of use in harsh

environments viz. drilling, mining, underwater, etc. where it is impractical or impossible to run wires.

• Automatic wireless charging for future hybrid and all-electric passenger and commercial vehicles, at home, in parking garages, etc.

• Direct wireless power connections and automatic wireless charging for implantable medical devices viz. ventricular assist devices, pacemaker, defibrilator, etc.

• Direct wireless powering of stationary devices viz. LCD TV’s, digital picture frames, home theater accessories, etc. eliminating expensive custom wiring, unsightly cables and wall power supplies.

Is it practical and is it safe?

• Witricity demonstration is still too recent, and too focused, to produce any definite conclusions.

• With the witricity method ,they anticipate transmitting power over distances about a meter, which is much less than ideal but still very impressive.

• If the technology is improved to a point where it can be “productized", it stands to revolutionize the field of wireless.

• Its discovery is different from all previous effort because it uses “magnetically coupled resonance", which means it will not only be safe but it will be fairly efficient.

1. An article published in the Science Magazine as “Wireless Power Transfer via Strongly Coupled Magnetic Resonances” by Andre kurs, Science 317, 83(2007); Dol:10.1126/ science.1143254.

2. H. Haus , “Waves and Fields in Optoelectronics”, Prentice hall Publishers, Englewood 3. http://electron9.phys.utk.edu/optics507/modules/m6/coupled_resonators.htm 4. “Efficient Non-Radiative Midrange Energy Transfer” by Aristeidies karalis, Marlin Soljacic. 5. Nikola Tesla, My Inventions, Ben Johnston, Ed., Austin, Hart Brothers, p. 91,1982.6. Thomas F. Valone, “ Tesla’ s Wireless Energy... For the 21st Century!!! One Step Beyond

Direct TV!!!” Extra Ordinary Technology, 1, no. 4, Oct / Nov / Dec 2003.7. James O. McSpadden, “ Wireless Power Transmission Demonstration”, Texas A&M

University, June, 1997.8. Charych Arthur (Setauket, NY), “ System and method for wireless electrical power

transmission”, Patent No. 6,798,716, September 28, 2004.9. Joe T. Howell, et. al , “Advanced receiver / converter experiments for laser wireless power

transmission”5th. Wireless transmission conference, pp 1-8, Garanda, Spain,2004.

Bibliography

Thank You