Download Wireless Electricity

“Wireless
Electricity”
PRESENTED BY
MRUDUL SHYAM

What do you mean by WiTricity?

Need of WiTricity

History of wireless power

WiTricity Basics
 The
Transfer of Electricity from one place to another
without wires is known as “WiTricity”.
 On
June 7,2007 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.
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
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.
 Currently,
wired electricity powers have concurred
nearly everything.
 In
the 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.
 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.
 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.
There are 3 major types of wireless energy transfer:
Short range- Inductive Coupling

Medium range -Resonant Induction

Long range -Electromagnetic Wave Power Transfer
 Inductive
Coupling is a method for short range
wireless energy transfer.

Its range can vary, but it’s often very short.
Inductive coupling works on
principles of electromagnetism:
the

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.
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.
Group of engineers at MIT
 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.
 Everything
resonates at a certain frequency, based on its
shape and material.
 With
resonant induction, power is transmitted between
two resonating coils.
 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.
One source is able to transfer the energy for
the electronic devices.
Sony demonstrated its wirelessly powered television
[2010 October]
Demonstration of WiTricity on cellphone and LCD at
the TED conference.
Batteries can be charged , it is just enough to place the
device to top of one of these surfaces.
Charging Electric Car using WiTricity.
 Human
beings or other objects placed between the
transmitter and receiver do not hinder the
transmission of power.
 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.
 Safe,
fairly efficient, good range.
 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.

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.

Think that the city will be covered with WiTricity hot
spots, just like Wireless Internet, there will be no
need of charging batteries, or carrying adapters all
around !