Wireless power transmission through resonance coupling was proposed over a century ago but recently rediscovered. It works by powering electromagnetic resonators at the same frequency so that energy transfers between their coupled magnetic fields, allowing devices to charge without wires. Researchers at MIT demonstrated this by lighting a bulb from a source over 2 meters away. Applications could include wirelessly powering devices, vehicles, and buildings to improve efficiency over transmission lines that incur large losses. While promising, wireless power systems require transmitters and receivers tuned to the same precise frequency for energy to transfer effectively over distances.

1. ELECTRICITY THROUGH
WIRELESS
TRANSMISSIONWITRICITY
by
AMBER BHAUMIK
PG-DESD

2. Introduction

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
power technology.

The transmission and distribution system
causes a loss of 26% to 30% of energy
generated.

The transmission of power without wires is

3. History of Wireless Power
In 1899, Sir Nikola Tesla Proposed
a method of Wireless Power
Transmission.
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
power loss.

4. 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

5. Need of Witricity:
* Cell phones, i pods, laptop computers are
capable of re-charging themselves without
ever being plugged in.

6. The forgotten invention is reborn in 2007
RESONANCE COUPLING

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.

7. Research at MIT
* Prof. Soljacic – Another
Genius
MIT-IBM Collaboration
* He did succeed to
redesign Tesla’s
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

8. Experiment demonstrated at MIT.
A 60W light bulb lit from source at a distance of 2m from
load.

9. Electric bulb lightened even when a barrier was
kept in between.

10. Types and Technologies

Near-field techniques
 Inductive
Coupling
 Resonant Inductive Coupling
 Air Ionization

Far-field techniques
 Microwave
Power Transmission (MPT)
 LASER power transmission

11. Inductive coupling


Primary and secondary coils are not
connected with wires.
Energy transfer is due to Mutual Induction

12. Cont…





Energy transfer devices are usually air-cored
Transformer is an example
Wireless Charging Pad(WCP),electric brushes
are some examples
Nokia Lumia 720
The charging pad (primary coil) and the
device(secondary coil) have to be kept very
near to each other

13. RESONANT INDUCTIVE COUPLING

The capacitor and inductor forms the resonator.
Charge oscillates between inductor (as magnetic
field) and capacitor (as electric field.)

This type of oscillation is called resonance if the
reactance's of the inductor and capacitor are
equal.

14. RESONANT INDUCTIVE COUPLING

Resonant transfer works by making a
coil ring with an oscillating current.

This generates an oscillating magnetic field.

Because the coil is highly resonant any energy
placed in the coil dies away relatively slowly
over very many cycles.

But if a second coil is brought near it, the coil
can pick up most of the energy before it is lost,
even if it is some distance away.

15. BLOCK DIAGRAM

16. BLOCK DIAGRAM



Oscillator used is an astable multivibrator using
555timer which switches IRFP250 to produce
oscillations in the primary coil.
Secondary coil kept at a distance resonates at
the same frequency and power transfer takes
place.
Signal received in the secondary is rectified and
regulated.

17. Resonant Inductive Coupling

18. RESONANT INDUCTIVE COUPLING



Inductive charging uses an electromagnetic
field to transfer energy between two objects.
Greater distances can be achieved by
using resonant inductive coupling.
Resonant inductive coupling or electrodynamic
induction is the near field wireless
transmission between two coils that are tuned
to resonate at the same frequency.

19. Air Ionization
Toughest technique under near-field energy
transfer techniques
 Air ionizes only when there is a high field
 Needed field is 2.11MV/m
 Natural example: Lightening
 Not feasible for practical
implementation.


20. Far-field energy transfer



Microwave Power Transfer(MPT)
Transfers high power from one place to another.
Steps:
Electrical energy to microwave energy
 Capturing microwaves using rectenna
 Microwave energy to electrical energy






AC can not be directly converted to microwave
energy
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

21. LASER transmission




LASER is highly directional, coherent
Not dispersed for very long
But, gets attenuated when it propagates
through atmosphere
Simple receiver
 Photovoltaic

Cost-efficient
cell

22. Applications

Direct Wireless Power
 No device needs wires
 For TVs, toasters or any form of
Immobile devices

Automatic Wireless Charging
 Device
with
rechargeable
batteries
charges itself
 For any form of mobile device

23. Some more Applications…
*Industrial

would be free of heavy installation of wires and devoid
of any hazardous electric shock incidents.
*Transportation

Could charge an electric car or automobile.

24. Wireless power transmission is
safe

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.

25. Advantages

Efficient and reliable power.

Provides solution to the ever increasing
demand for power.
A solution to reduce e-waste- a more safe
environment.
A more cost effective methodology for getting
electricity to your houses which includes
paying less for use of power.



26. Disadvantages.
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.


27. CONCLUSION
Transmission without wires- a reality
 Efficient
 Low maintenance cost. But, high initial
cost
 Better than conventional wired transfer
 Energy crisis can be decreased
 Low loss
 In near future, world will be completely
wireless
