1. TRISHA SINGH
B070309EE
*

2. *Wireless power transmission dates back to the
19th century when Nikola Tesla used conduction-
based systems to transfer wireless power.
*A couple of techniques of wireless power
transmission are known now:
*Direct induction
*Resonant magnetic induction
*Electromagnetic radiation
*

3. *
*WiTricity stands for wireless electricity.
*It is a trademark of WiTricity Corporation
*It refers to their devices and processes which
employ wireless energy transfer through resonant
inductive coupling.
*It is used to describe the ability to provide
electricity to remote objects without wires, using
oscillating magnetic fields

4. *The first experiment of WiTricity was
conducted in the year 2006 by a five-
member team of researchers from
Massachusetts Institute of Technology.
*It was led by Assistant Professor Marin
Soljačić.
*It was funded by Army Research Office,
National Science Foundation and the
Department of Energy.
*
*

5. *Resonance is the tendency of a system to oscillate
with larger amplitude at some frequencies than at
others.
* At the resonant frequencies, even small periodic
driving forces can produce large amplitude
oscillations, because the system stores vibrational
energy.
*Two objects having similar resonance tend to
exchange energy without causing any effects on the
surrounding objects.
*

6. *Just like in acoustic resonance,
where there is a chance of a
glass breaking if you strike the
right tone.
*A wine glass captures sound
energy that oscillates at its
natural resonant frequency,
converts it to mechanical
energy that causes the glass to
deform at that same frequency
and eventually causing it to
shatter.
*

7. *Two copper coils of diameter
two feet
*The transmitter coil was
attached to a power source
*The receiver coil was placed
about seven feet from the
transmitter
* This receiver was attached to
a light bulb and
*The two coils were tuned to
the same frequency
*Power was switched on at the
transmitter
*
*

8. *The coils magnetically coupled
and resonated at 10MHz.
*Electric energy was
transmitted over a distance of
two meters, through the air
and around an obstacle.
*With each cycle, more
pressure and voltage built up
in the coil till the
accumulation of voltage
provided enough pressure and
energy to flow to the light
bulb
*
*

9. *Data collected through
measurements showed that
there was transference of 40%
of electricity through
WiTricity.
*The bulb glowed despite the
fact that wood, metal and
other devices were placed in
between the two coils
*
*

10. *The blue lines represent the
magnetic near field induced
by the power source.
*The yellow lines represent the
flow of energy from the source
to the WiTricity capture coil.
*The magnetic field (blue lines)
can wrap around a conductive
obstacle between the power
source and the capture
device.
*
*

11. * WiTricity is based on strong coupling between electromagnetic resonant
objects to transfer energy wirelessly between them. This differs from other
methods like simple induction, microwaves, or air ionization.
* The system uses two coils - one plugged into the mains (transmitter) and the
other embedded or attached to the gadget(receiver). Each coil is carefully
engineered with the same resonant frequency.
*

12. * When the main coil is connected to an electricity supply, the magnetic field it
produces is resonant with that of with the second coil, allowing "tails" of energy to
flow between them.
* As each "cycle" of energy arrives at the second coil, a voltage begins to build up
that can be used to charge the gadget.
* Due to operating in the electromagnetic near field, the receiving devices must be
no more than about a quarter wavelengths from the transmitter, which usually
comes to around a few meters.
*

13. *

14. *
*WiTricity's mode of wireless power transfer is highly
efficient over distances ranging from centimeters to
several meters. In many applications, efficiency can
exceed 90%.
*Also, WiTricity sources only transfer energy when it is
needed.
* When a WiTricity powered device no longer needs to
capture additional energy, the WiTricity power source will
automatically reduce its power consumption to a power
saving “idle” state.
*

15. *Energy Transfer via Magnetic Near Field Can
Penetrate and Wrap Around Obstacles
*Flexible Geometry Allows WiTricity Devices
to be embedded into OEM Products
*Scalable Design Enables Solutions from
milliwatts to Kilowatts
*

16. *
*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.
*The exposure levels are below the threshold for FCC safety
regulations, and the radiated-power levels comply with the
FCC radio interference regulations
*

17. *Wirelessly powering up an appliance will not add up appreciably
to the costs; though in the early days, the charging costs maybe
up to 10-15% higher than in wired appliances
*

18. *An electric toothbrush uses traditional
magnetic induction to recharge its batteries.
*The tooth brush needs to be placed in its
cradle in order to be recharged, because the
coils must be within millimeters of each other
to couple and transfer power.
*
*However, WiTricity’s specially designed magnetic resonators
enable strong coupling and highly efficient energy exchange
over distances much larger than the size of the resonator
coils, distances very large compared to traditional schemes.

19. *Radiative power transfer-
*Broadcasted radiation
*Directed radiation
*Laser
*
*WiTricity’s technology for power transfer is non-radiative
and relies on near-field magnetic coupling. It does not
require a clear line of sight between the power sources and
capture devices and it is safe for use in typical home,
hospital, office, or industrial environments.

20. *Back in the 19th century, Nikola Tesla used
conduction- based systems to transfer wireless
power.
*However, his grand scheme to beam electricity
around the world ran out of funding.
*Also, interest in wireless power transmission
faded away soon as the industrial world
willingly adopted the wired approach.
*
*WiTricity technology for power transfer is
different than the technologies proposed
by Tesla, but his work is referenced and
acknowledged in the scientific articles
published by WiTricity’s founding technical
team.
Wardenclyffe tower

21. *WiTricity’s wireless power transfer technology can be applied
in a wide variety of applications and environments.
*WiTricity technology can be used to provide:
*Direct Wireless Power - when all the power a device needs is
provided wirelessly, and no batteries are required. This mode
is for a device that is always used within range of its WiTricity
power source.
*Automatic Wireless Charging - when a device with
rechargeable batteries charges itself while still in use or at
rest, without requiring a power cord or battery replacement.
This mode is for a mobile device that may be used both in and
out of range of its WiTricity power source.
*

22. *Consumer electronics
*
*Industrial

23. *Transportation
*
*Miscellaneous

24. *

25. *With the advent of portable electronics that seem to need
constant charging, researchers are exploring ways to
make wireless electricity practical. In addition, plug-in
electric vehicles are another motivating factor, as
plugging in a car or forgetting to plug one in, is a burden
that consumers may not want to bear.
*WiTricity Corp. is working towards miniaturizing and
packaging the technology so that it can be built directly
into a wide variety of products and systems—with no need
for an external power capture device as shown in the
prototype configuration.
*

26. *André Kurs, AristeidisKaralis, Robert Moffatt, J. D.
Joannopoulos, Peter Fisher, Marin Soljačić, ―Wireless
Power Transfer via Strongly Coupled Magnetic
Resonances‖, Science, Vol. 317, no. 5834, 6 July 2007, pp.
83-86
*AristeidisKaralis; J.D. Joannopoulos, Marin Soljačić,
"Efficient wireless non-radiative mid-range energy
transfer",Annals of Physics,April 2007, Vol. 323, pp. 34–48
*WiTricity Corporation, http://www.witricity.com as on
January 9, 2011
*