1. --The Wireless Electricity.
By
Karan Bir Singh
E073026

2. What is witricity?
Witricity is nothing but wireless electricity.
Transmission of electrical energy from one
object to another without the use of wires is
called as Witricity.
Because of Witricity some of the devices
won't require batteries to operate.

3. The story started late one night a
few years ago. It was probably
the sixth time that month that
.
MIT Professor Marin Soljacic
was awakened by his mobile
phone beeping battery low. At
that time it occurred to him that
there is electricity wired all
through his house, office-
everywhere. He think about- how
it is possible to use electricity
without using wires…

4. Electro
magnetism
Resonant
magnetic
coupling
RESONANCE

5. Electromagnetic induction is the
production of voltage across a
conductor 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 interaction
between electrically charged
particles; the areas in which this
happens are called electromagnetic
fields
Energy/Power Coupling: Energy
coupling occurs when an energy
source has a means of transferring
energy to another object

6. Resonance :is the tendency of a
system to oscillate with larger
amplitude at some frequencies than
at others. These are known as the
system's resonant 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 varying or oscillating
magnetic fields. Resonant coupling
occurs when the natural
frequencies of the two objects are
approximately the same.

7. The Transfer of Electricity from one place to another without
wires is known as “Witricity”.
There is witricity power sources(transmitter) and capture
devices(receiver).
Power source provides power to the devices where as capture
device captured it to work.
Power source and capture devices are specially designed
magnetic resonators.
Magnetic resonators efficiently transfer power over mid-range
distance via the magnetic near-field.

8. Near field
 Near field is a wireless transmission
technique over distances comparable to or a
few times the diameter of devices.
 Near field is usually magnetic.
 Near field energy is non radiative .but some
radiative and resistive losses will occur.

9. Coupled resonators
 Two resonant objects of the same resonant
frequency tend to exchange energy.
 It exchange energy strongly ,while interacting
weakly with living beings and other
environmental objects.
 Coupled resonators are said to be operate in
strongly coupled regime to avoid material
absorption and radiative loss.

10. MIT teams behind witricity technology
The first experiment of witricity, the concept of wireless
electricity, was conducted in the year 2006, by researchers
from Massachusetts Institute of Technology. The Assistant
Professor of this team of researchers was Marin Soljacic.
2007: A physics
research group, led by
Prof. Marin Soljacic,at MIT,
wirelessly power a 60W
light bulb with 40%
efficiency at a 2 meters
(6.6 ft) distance using two
60 cm-diameter coils

12. Schematic Diagram

13. Diagram of power source and capture
device
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 powers light bulb.
The magnetic field can wrap around
the obstacle between power source and
capture coil.

14. Range & Rate of Coupling:
Using Coupled Mode Theory (CMT), we can give some frame work
to the system. The field system of the two resonant objects 1, 2 is
F(r,t)=a1(t)F1(r)+a2(t)F2(r)
Where F1,2(r) are the resonating modes of 1 and 2 alone, and then the field
amplitudes a1(t) and a2(t).The lower order representation of the system is
given by :
Where ω1, 2 are the individual frequencies, Γ1, 2 are the Resonance widths
(Decay rates) due to the objects’ intrinsic (absorption, radiation etc.) losses,
and ‘κ’ is the coupling coefficient .

15. The solution of the equation show that at exact resonance at
ω1=ω2 and Γ1=Γ2
the normal modes of the combined system are split by 2κ.
Ratio {κ /sqrt (Γ1, 2)} shows that, it will set as figure-of-
merit for any system under consideration for wireless energy-
transfer, along with the distance over which this ratio can be
achieved.
 The desired optimal regime {κ/sqrt (Γ1,2)>>1} is called
“Strong-Coupling” regime. There is No change in Energy,
unless κ/Γ>>1 is true.

16. Simulation model Using COMSOL:
Simulation Performance:
 By the basic parameters, calculated results and performance
given with and Without the External object in between the coils.

17. Comparison of Results:
Results without Extraneous objects:
Two loops D/r Qrad Q=ω/2Γ ω/2κ κ/ Γ
R=30cm,a=2mm, 3 30729 4216 63.7 68.7
ε=10, 5 29577 4194 248 17.8
d=4mm,Qabs=4886.
Results with Extraneous objects:
Two loops D/r Qrad Q=ω/2Γ ω/2κ κ/ Γ
R=30cm,a=2mm, 3 30729 4136 62.6 67.4
ε=49+16i,
5 29577 4106 235 17.6
d=4mm,Qabs=4886.

20. Witricity technology is more than…
 Traditional magnetic induction.
Radiative power transfer.
Tesla’s vision of a wireless world.

21. Used in power transformers.
 conductive coils transmit power to each
other wirelessly, over very short distance.
An electric tooth brush uses
traditional magnetic induction to
recharge its batteries

22. Radio frequency energy is used for wireless
power transfer.
Radiated power is wasted into free space
Need line of sight.
Harmful.
Microwave oven utilizes
radiation to cook foods

23. Nikola Tesla the most well known scientist
had a vision of wireless world.
In which wireless electric power and
communication would reach around the world,
delivering information and power.
WardenclyffeTower
Dec 1914
US Patent No. :1,119,732

24. Features and benefits
Witricity’s Technology Technology Benefit
Highly resonant strong coupling High efficiency over distance
Energy transfer via magnetic near Can penetrate and wrap around
field obstacles
Non radiative energy transfer Safe for living beings and other
environmental objects
Scalable design From Mw to kW
Flexible geometry Device that can fit into OEM (original
equipment manufactures)products

25. Applications

26. WITRICITY APPLICATIONS
Automatic wireless charging of
mobile electronics in home, car,
office,...while devices are in use
and mobile.
Direct wireless powering of
stationary devices…eliminating
expensive custom wiring,
unsightly cables and “wall-wart”
power supplies.

27. Robots, package
machinery, assembly
machinery, machine
tools.
Direct wireless power
and communication
interconnections at
points of use in harsh
environments.
Direct wireless power for
wireless sensors and
actuators, eliminating
the need for expensive
power wiring or battery
replacement and
disposal.

28.  Automatic wireless
charging for existing
electric vehicle classes:
golf carts, industrial
vehicles.
 Automatic wireless
charging for future hybrid
and all-electric passenger
and commercial vehicles,
at home, in parking
garages, at fleet depots,
and at remote kiosks.

29. Other Applications
 Direct wireless power
interconnections and
automatic wireless
charging for implantable
medical devices .
 Automatic wireless
charging and for high tech
military systems.
 Direct wireless powering
and automatic wireless
charging of smartcards.
 Direct wireless powering
and automatic wireless
charging ofconsumer
Appliance, mobile robots,
etc.

30. ADVANTAGES
 No need of line of sight.
 No need of power cables
and batteries.
 Does not interfere with
radio waves. Wastage of power is small
.
Negative health
implications.
Highly efficient than
electromagnetic induction
Less costly.

31. Limitations:
☼ The resonance condition should be satisfied and
if any error exists, there is no possibility of power
transfer.
☼ If there is any possibility of very strong
ferromagnetic material presence causes low power
transfer due to radiation.

32. References
• Wireless Power Transfer via Strongly Coupled Magnetic Resonances André
Kurs,Aristeidis Karalis,Robert Moffatt,1 J. D. Joannopoulos,Peter Fisher,
Marin Soljacˇic´ .
• Efficient wireless non-radiative mid-range energy transfer Aristeidis
Karalis*, J.D. Joannopoulos, and Marin Soljačić Center for Materials
Science and Engineering and Research Laboratory of Electronics
Massachusetts Institute of Technology, 77 Massachusetts Avenue,
Cambridge, MA 02139, USA .
• Magnetic Resonant Coupling As a Potential Means for Wireless Power
Transfer to Multiple Small Receivers.