In our present electricity generation system
we waste more than half of its resources.
Especially transmission and distribution
losses are main concern of the present
The transmission and distribution system
causes a loss of 26% to 30% of energy
The transmission of power without wires is
History of Wireless Power
In 1899, Sir Nikola Tesla Proposed
a method of Wireless Power
Nikola Tesla – The Genius
He enlighted 200 lamps at the
distance of 40 km, Wirelessly !
The efficient midrange power
transfer concept is Witricity. In this
model source and load are in
Magnetic resonance so there is no
Research at MIT
* Prof. Soljacic – Another
* He did succeed to
experiment in safer way.
* They had lit up a 60W
bulb with a power source
at a distance of 7 feet(over
2m) with no wires
The forgotten invention is reborn in 2007
A group of engineers at MIT came up with the idea to use
resonant induction to transmit power wirelessly.
“Resonance", a phenomenon that causes an object to vibrate when
energy of a certain frequency is applied.
Need of Witricity:
* Cell phones, i pods, laptop computers are
capable of re-charging themselves without
ever being plugged in.
What is WiTricity ?
definition is :
* “Transmission of energy through the air”.
* A system of two electromagnetic
resonators coupled mostly through
their magnetic fields.
** Cables are going to replaced by WiTricity.
Efficient power transfer
Types and Technologies
Resonant Inductive Coupling
MicrowavePower Transmission (MPT)
LASER power transmission
Primary and secondary coils are not
connected with wires.
Energy transfer is due to Mutual Induction
Energy transfer devices are usually air-cored
Transformer is an example
Wireless Charging Pad(WCP),electric brushes
are some examples
The charging pad (primary coil) and the
device(secondary coil) have to be kept very
near to each other
* Same concept as Inductive coupling just
that the coils operate at resonant
frequency leading to efficient transfer of
energy over a larger distance.
* Interacts weakly with extraneous off resonant
* Radiation loss will be negligible
Toughest technique under near-field energy
Air ionizes only when there is a high field
Needed field is 2.11MV/m
Natural example: Lightening
Not feasible for practical
Far-field energy transfer
Microwave Power Transfer(MPT)
Transfers high power from one place to another.
Electrical energy to microwave energy
Capturing microwaves using rectenna
Microwave energy to electrical energy
AC can not be directly converted to microwave
AC is converted to DC first
DC is converted to microwaves using magnetron
Transmitted waves are received at rectenna
which rectifies, gives DC as the output
DC is converted back to AC
LASER is highly directional, coherent
Not dispersed for very long
But, gets attenuated when it propagates
Direct Wireless Power
No device needs wires
For TVs, toasters or any form of
Automatic Wireless Charging
Device with rechargeable
For any form of mobile device
Some more Applications…
* Consumer electronics.
would be free of heavy installation of wires and devoid
of any hazardous electric shock incidents.
Could charge an electric car or automobile.
Wireless power transmission is
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.
Efficient and reliable power.
Creation of a shock free environment devoid of
any chances of power thefts.
Provides solution to the ever increasing demand
A solution to reduce e-waste- a more safe
A more cost effective methodology for getting
electricity to your houses which includes paying
less for use of power.
Not affected by the day and night cycle, leads to
lesser limitations on power harvesting.
For short and mid range transfer system
has to be set at the right frequency or
there would be no power transfer.
For long range the installation cost is high.
Transmission without wires- a reality
Low maintenance cost. But, high initial
Better than conventional wired transfer
Energy crisis can be decreased
In near future, world will be completely