What is wireless power transfer
Why not wires..?
Methods of WPT
Merits and demerits
3 EEE NMIT 2014
4. What is Wireless power transfer
The transmission of energy from one place to
another without using wires.
Solution is WiTricity.
WPT emerges out as the best alternative for
efficient power transmission.
4 EEE NMIT 2014
Nikola Tesla -Pioneer of induction techniques
His vision for “World Wireless System”
In 1894 Nikola Tesla used resonant inductive coupling, also
known as "electro-dynamic induction" to wirelessly light up
incandescent lamps .
1897 he patented a device called
high-voltage resonance transformer or"Tesla coil” capable of
very high voltagesat high frequency.
In 1899 - an aerial tower called Wardenclyffe .
which was meant to be a pilot plant for his “World Wireless
System” to broadcast energy around the globe.
The idea of Tesla is taken in to research after 100 years in 2007.
5 EEE NMIT 2014
Nikola Tesla (1856 - 1943)
6. Why Not Wires ?
As per studies, most electrical energy transfer is
Most of the energy loss is during transmission
On an average, more than 30%
In India, it exceeds 40%
Risk of electrical hazards
Complicated wiring structure
Maintenance cost is high.
6 EEE NMIT 2014
7. Why wireless…?
Low maintenance cost
Can be used for short-range or long-range.
7 EEE NMIT 2014
8. Method Of WPT
There are mainly 5 method to transfer power
LASER power transmission
Resonant Inductive Coupling
Microwave Power Transmission (MPT)
8 EEE NMIT 2014
9. For the application of
Short range – INDUCTIVE COUPLING, AIRIONIZATION
9 EEE NMIT 2014
LASER POWER TRANSMISSION
Medium range – RESONANT INDUCTION
Long range power transfer – MICROWAVE POWER
10. Inductive coupling
The principle of mutual induction between two coils
can be used for the transfer of electrical power.
The simplest example is
where there is no physical contact
between the primary and the secondary
10 EEE NMIT 2014
11. Air ionization
Toughest technique under near-field energy transfer
Air ionizes only when there is a high field
Needed field is 2.11MV/m
Natural example: Lightening
Not feasible for practical implementation
11 EEE NMIT 2014
12. Laser power transmission
LASER is highly directional, coherent
Not suitable for very long
gets attenuated when it propagates through
12 EEE NMIT 2014
13. Need of Resonance coupling
transformers work on the principle of inductive
coupling, short range power transfer & requires
a magnetic core.
Over greater distances this method is highly
inefficient and wastes the majority of the energy in
resistive losses of the primary coil.
concept of resonant coupling comes where two
coils are tuned to a particular frequency called
resonating frequency & absorb optimal energy.
13 EEE NMIT 2014
14. 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 EEE NMIT 2014
16. RIC continue…..
This wireless power transmission concept based
on strongly-coupled resonator.
Time taken for energy transfer is less than the
time of loss . So high efficiency.
Since the resonant wavelength is much larger
than the resonators, the field not need of line-of-sight.
This method is safe, since magnetic fields interact
weakly with living organisms..
16 EEE NMIT 2014
17. Microwave Power
In this method Electrical energy is converted to
AC is converted to DC first then this DC is
converted to microwaves using magnetron.
This wave is Captured using rectenna and convert
Microwave energy to electrical energy.
THIS Methord is used where transfers high power
from one place to another being in line of sight
17 EEE NMIT 2014
Transmitted waves are received at rectenna.
Consists of mesh of dipoles and diodes
Converts microwave to its DC equivalent
DC is converted back to AC
Usually multi-element phased array
Eg. Solar power satellite
18 EEE NMIT 2014
19. Merits of WPT
Eliminates the existing transmission line cables, towers and
More freedom of choice of both receiver and transmitters
Cost of transmission and distribution become less.
Power could be transmitted to the places where the wired
transmission is not possible.
Loss of transmission is negligible level.
Safer by eliminating the sparking hazard.
19 EEE NMIT 2014
20. More Reliable/Less Costly
- Never run out of battery power in wireless zones
- Power transfers more efficiently than through wires
- No more changing batteries
- No messy cords to carry.
- Reduces the use of disposable batteries
- Reduces energy loss
20 EEE NMIT 2014
The Capital Cost for practical implementation of WPT
seems to be very high.
Interference of microwave with present communication
Common belief fears about the effect of microwave
radiation among peoples
When LASERs are used,
21 EEE NMIT 2014
conversion is inefficient
Absorption loss is high
22. Biological Impact
Institute of Electrical and Electronic Engineers
(IEEE) and by the International Commission on Non-
Ionizing Radiation Protection (ICNIRP).
Experimently prooved that
no radio frequency (RF) electromagnetic fields
but there is a very small increase a person’s body
temperature or may heat body tissues and may
stimulate nerve and muscle tissues.
22 EEE NMIT 2014
23. Is WiTricity Secure ?
Principle is based on Magnetic Waves.
The question is if Magnetic Waves Secure ?
The answer is we all live in a globe that has already
surrounded by magnetic waves.
Yes it is secure !
23 EEE NMIT 2014
29. 6, Led lighting
LED (light emitting diode) lights can be directly powered with
wireless electricity ,which eliminate
the need for batteries enabling architectural lighting
designers to create products that seemingly float in mid-air,
with no power cord.
29 EEE NMIT 2014
30. Defense Systems
Photographs showing several military applications for
highly resonant wireless
charging systems: military robots (left) and soldier
30 EEE NMIT 2014
31. Future of WiTricity
Think that the city will be covered with WiTricity hot
spots like wi-fi.
which eliminate need of charging batteries or carrying
adapters all around !
Transport system become wirelessly powered
which eliminate fuel engines.
Which will give rise to the Robotic Technology
they will work for us 24 H 365 days without any
31 EEE NMIT 2014
Transmission without wires- a reality
Low maintenance cost. But, high initial cost
Better than conventional wired transfer
Energy crisis can be decreased
Low energy wastage
In near future, world will be completely
32 EEE NMIT 2014
Highly Resonant Wireless Power Transfer:
Safe, Efficient, and over Distance by Dr. Morris Kesler
W“iWTririceilteys.s Power Transmission”, Vol No.-45, Electronics For
Peter Vaessen,” Wireless Power Transmission”, Leonardo
Energy, September 2009
C.C. Leung, T.P. Chan, K.C. Lit, K.W. Tam and Lee Yi Chow,
“Wireless Power Transmission and Charging Pad”
White Paper on Solar Power Satellite (SPS)
Systems, URSI, September 2006
Richard M. Dickinson, and Jerry Grey, “Lasers for
Wireless Power Transmission”
David Schneider, “Electrons unplugged”, IEEE
Spectrum, May 2010
33 EEE NMIT 2014