The document discusses 'witricity,' or wireless electricity, which allows the transfer of power without wires, highlighted by MIT's successful demonstration in 2007. It traces the history from Nikola Tesla's early concepts to modern applications, detailing various methods such as inductive coupling and resonant induction, along with their efficiencies and potential benefits. The document addresses safety concerns, efficiency challenges, and the future prospects of witricity in consumer electronics and beyond.

2. “Wireless Electricity”
PRESENTED BY: SHAIK SARTAJ
AHMED

4.  What do you mean by Wi Tricity ?
 Need of witricity
 History of wireless power
 Witricity Basics
 Detailed Principle
 How Safe is Wi Tricity ?
 What's the Future of WiTricity ?
 Advantages
 Limitations
 Bibliography

5.  The Transfer of Electricity 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.

6. In 1891, Sir Nikola Tesla
Proposed a method of Wireless
Power Transmission.
As it is in Radiative mode,
most of the Power was wasted
and has less efficiency.

 In 2005, Dave Gerding coined the term WiTricity
which is being used today.
 Forgotton invention was reborn in 2007

7.  In 1891, Nikola Tesla invented a type of resonant
transformer called the Tesla coil, which was used
to generate very high voltage, low current, and
high frequency alternating electricity. He
experimented with a large variety of coils and
configurations, one of which is as:

8.  In1899,Tesla achieved a
major breakthrough in
his work at Colorado by
transmitting 100 million
volts of electric power
wirelessly over a
distance of 26 miles to
light up a bank of 200
light bulbs and run one
electric motor.

9.  Cell phones, i pods, laptop computers are capable
of re-charging themselves without ever being
plugged in.

10.  Currently, wired electricity powers have concured
nearly everything.
 In present electricity generation system we
waste more than half of its resources. Especially
the transmission and distribution losses are the
main concern of the present power technology.

11.  The resistance of the wire used in the electrical
grid distribution system causes a loss of 26-30%
of the energy generated
 The transmission of power without wires may be
one noble alternative for electricity transmission.

12.  Prof. Marin Soljacic from Massachusetts
Institute of Technology (MIT), is the one who
has proved that magnetic coupled resonance
can be utilized in order to transfer energy without
wires.
 He used Michael Faraday's principle of
electromagnetic induction (1831) came up with
WiTricity.

14.  There are 3 major types of wireless energy
transfer:
 – Short range; Inductive Coupling
 – Medium range; Resonant Induction
 – Long range; Electromagnetic Wave Power
Transfer

15.  What Is Inductive Coupling?
 Inductive Coupling is a method for short range
wireless energy transfer.
 Its range can vary, but it’s often very short.

16.  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.

17.  What Is Resonant Induction?
 A group of engineers at MIT came up with
the idea to use resonant induction to
transmit power wirelessly. They deemed
their result “WiTricity” (like Wi-Fi) .
WiTricity can transmit electricity
wirelessly at 40% efficiency to about 7
feet.

18.  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.

20.  Everything resonates at a certain frequency,
based on its shape and material.
 Energy transfers easily between resonating
objects. An example of this is when an opera
singer shatters wine glasses by singing at the
frequency at which the glasses resonate.
 With resonant induction, power is transmitted
between two resonating coils.

22.  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 , while the other copper wire is
connected to the device.

24.  A Tesla Coil produces high voltage electric arcs.
These arcs cause permanent damage to electrical
devices on contact
 Tesla coils also destroy hearing aids and cardiac
pacemakers in their vicinity.

25.  Is WiTricity safe?
 How much power can be transferred?
 What about the range of transferred?
 How efficient is WiTricity?
 What's the Future of WiTricity?

26.  The rate of energy transfer between the emitter
and the receiver is greater than the rate of
energy dissipation.
 Efficiency is mesured by measuring the current
at the midpoint of the self resonant coils with a
current probe.
 This gives a measurement of the current
parameters

27.  We then compute power dissipated in each coil from:-
 Then the efficiency can be calculated .

28.  Direct Wireless Power
◦ No device needs wires
◦ Immobile devices
 Automatic Wireless Charging
◦ Device with rechargeable batteries
◦ charges itself
◦ Mobile device
◦ Used in and out of range of its
WiTricity power source

29.  Consumer Electronics
 Industrial
 Transportation
 Miscellaneous

30.  Will it harm me?
 Will it harm the environment?
 Will it interfere with important communication?

31.  Human beings or other objects placed between
the transmitter and receiver do not hinder the
transmission of power.
 However, does magnetic coupling or
resonance coupling have any harmful effects on
humans?
 magnetic fields tend to interact very weakly
with the biological tissues of the body, and so
are not prone to cause any damage to any living
beings.

32.  Safe, fairly efficient, good range:
 Magnetic fields interact weakly with biological
masses (humans),
 Efficiency can be increased with time, most of the
60% lost is from heat radiated from the coils.
 Theoretically one stationary coil in a room could
power multiple devices with receiving coils.
 No more messy wires, and with widespread
enough use it could even eliminate costly
batteries.

33.  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.

34.  MIT's WiTricity is only 40 to 45% efficient and they
have to be twice as efficient to compete with the
traditional chemical batteries.
 Aim is to get a robotic vacuum or a laptop working,
charging devices placed anywhere in the room
 The researchers have said that in another five
years time, they will come up with a WiTricity
system for commercial use.

35. 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. Thom as F. Valone, “ Tesla’ s Wireless Energy... For the 21 st 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.