WiTricity: Wireless ElecTricity

Submit ted to:Dr. A K Jain ProfessorDepartment of ICE

Submit ted by: Sumit KumarM.Tech 2nd

Roll no.: 14214013

Content

• What is WiTr ic i ty?• History of Wireless power• Experimental design of WiTr ic i t y technology• WiTr ic i t y basics• Wireless energy transfer techniques• Work ing pr incip le of WiTr ic i t y• Is WiTr ic i t y safe?• WiTr ic i t y Applicat ions• Benefits and Advantages• Limitat ions• Conclusion• 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

We human love electricity !And to power our electronics devices we buy..

..

Which ends as…..

Which 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 million batteries per year add to the e-waste burden.And of course its not a good sign.

History of Wireless power In late 1890’s, Sir Nikola Tesla proposed the method of

wireless 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 wasted

and less efficiency about 15% only. In 2005, Dave Gerding coined the term WiTricity

which is being used today. Wireless elecTricity

Built the wardenclyffe tower(Tesla tower) which could broadcast power

wirelessly using far-field techniques. Called off as it

radiated power into surroundings raising issues of

power lossPower theft

Health concerns

The forgotten invent ion is reborn in 2007

The idea of wireless electricity has been

around since the earlydays of the Tesla coil.

But thanks to a group of MIT scientists, "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 to

successfully transmit power to a bulb within a distance of 2m at a

freq of 9.9MHz .

They use concepts of non radiative mid range energy

transfer, Resonance, inductive coupling.

Efficiency at that point was just approximately 43%.

Exper imenta l design

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 TechnologyPower 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.

Basics o f w i t r i c i t y

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 a distance 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 a conductor moving through a magnetic field.

• Energy/Power Coupling: Energy coupling occurs when an energy source has a means of transferring energy to another object.

Types of wireless energy transfertechniques

Short range– Inductiv

e couplin

g

Mid range– Resona

nce Inductiv

e couplin

gLong

range- Electroma

getic 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 aresome examples

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

How does Resonant Induction work??

• Resonant induction still uses the same principles as magnetic induction (magnetic fields to transfer current) , but it uses resonance to increase the range

at which the transfer can efficiently take

place.

• “Resonance", a phenomenon that causes an object to vibrate when energy 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.

How 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 source antenna. 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 energy transfer, relying instead on the magnetic near field.

• Magnetic fields interact very weakly with biological organisms—people and animals—and are scientifically regarded to be safe.

• WiTricity products are being designed to comply with applicable safety standards and regulations.

WiTricity ApplicationsConsumer 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 in

harsh 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)

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.

More Environmentally Friendly:• -Reduce use of

disposable batteries.•

-Use efficient electric ‘grid power’ directly.

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.• Ewaste is eliminated.• More secure, no risk of getting

shocked.• Maintenance cost will be

saved.

Limitations

• Transmissions possible only in few meters.

• Possibility 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.

ConclusionThink that the city will be covered withWPT hot spots, just like wireless internet,there will be no need of charging batteries,or carrying adaptors all around.

Future 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

• Peter Vaessen,” Wireless Power Transmission”, Leonardo Energy, September 2009.

• Richard M. Dickinson, and Jerry Grey, “Lasers for Wireless Power Transmission”.

• White Paper on Solar Power Satellite (SPS) Systems, URSI, September 2006.

• Richard M. Dickinson, and Jerry Grey, “Lasers for Wireless Power Transmission”.

• T. R. Robinson, T. K. Yeoman and R. S. Dhillon, “Environmental impact of high power density microwave beams on different atmospheric layers”.

• C.C. Leung, T.P. Chan, K.C. Lit, K.W. Tam and Lee Yi Chow, “Wireless Power Transmission and Charging Pad”.

• David Schneider, “Electrons unplugged”, IEEE Spectrum, May 2010.