2. Overview
What is wireless power transmission(WPT)?
Why is WPT?
History of WPT
Types of WPT
Techniques to transfer energy wirelessly
Advantages and disadvantages
Applications
Conclusion
References
3. What is WPT?
The transmission of energy from one
place to another without using wires
Conventional energy transfer is using
wires
But, the wireless transmission is made
possible by using various
technologies
4. History
Nikola Tesla in late 1890s
His vision for “World Wireless System”
The 187 feet tall tower to broadcast energy
All people can have access to free energy
Shortage of fund lead to nonoperation
He used to lamp 200 lights from 40 km
distance
5. Types and Technologies of
WPT
Near-field techniques
Inductive Coupling
Resonant Inductive Coupling
Air Ionization
Far-field techniques
Microwave Power Transmission
(MPT)
LASER power transmission
6. Inductive coupling
Primary and secondary coils are not
connected with wires.
Energy transfer is due to Mutual Induction
Wireless Charging Pad(WCP) ,Electric
Brushes are some examples.
7. Resonance Inductive
Coupling(RIC)
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.
8. 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
9. Advantages & Disadvantages
of near-field techniques
Advantages:
No wire, No e-waste
Need for battery eliminated
Efficient & Harmless
Disadvantages:
Distance constraint
Field should be under safety level
High initial cost
10. Microwave Power
Transfer(MPT)
Transfers high power from one place to
another. Two places being in line of sight
usually
Steps:
Electrical energy to microwave energy
Capturing microwaves using rectenna
Microwave energy to electrical energy
AC is converted to DC first
DC is converted to microwaves using
magnetron
11. MPT(Continued….)
Transmitted waves are received at rectenna
which rectifies, gives DC as the output
DC is converted back to AC
Rectenna:
Stands for rectifying antenna
Consists of mesh of dipoles and diodes
Converts microwave to its DC equivalent
Usually multi-element phased array
12. SOLAR POWER SATELLITE
Solar Power Satellites (SPS) have proposed to collect solar
energy in space and beam it down to the Earth.
13. Solar Power Satellites (SPS)
To provide energy to earth’s increasing
energy need
To efficiently make use of renewable
energy i.e., solar energy
SPS are placed in geostationary orbits
Each SPS may have 400 million
photocells
Efficiency exceeds 95%
if microwave is used.
14. Why to use SPS???
There is no air in space, so the satellites would receive
somewhat more intense sunlight, unaffected by weather.
The SPS concept is simpler than most power systems here
on earth.
Solar radiation can be more efficiently collected in space,
where it is roughly three times stronger than on the surface
of the Earth and it can be collected 24 hours per day
(since there are no clouds or night in high Earth orbit).
SPS does not use up valuable surface area on the Earth
15. Four basic steps involved in the conversion of solar energy to
electricity and delivery are:
Capture solar energy in space and
convert it to electricity
Transform the electricity to radio
frequency energy and transmit it to
Earth
Receive the radio frequency energy on
Earth and convert it back to electricity
Provide the electricity to the utility grid
16.
17.
18. Unlimited energy resource
Energy delivered anywhere in the world
Zero fuel cost
Zero CO2 emission
Minimum long-range environmental impact
Solar radiation can be more efficiently collected in space
19. Launch costs
Capital cost even given cheap launchers
Would require a network of hundreds of satellites
Possible health hazards
The size of the antennas and rectennas
Geosynchronous satellites would take up large sections of space
Interference with communication satellites
20. LASER transmission
LASER is highly directional, coherent
Not dispersed for very long
But, gets attenuated when it
propagates through atmosphere
Simple receiver
Photovoltaic cell
Cost-efficient
21. LASER vs. MPT
When LASER is used, the antenna sizes
can be much smaller
Microwaves can face interference (two
frequencies can be used for WPT are
2.45GHz and 5.4GHz)
LASER has high attenuation loss and also it
gets diffracted by atmospheric particles
easily
22. Advantages & Disadvantages of
Far Field Technology
Advantages:
Efficient , Easy
Need for grid
eliminated
Low maintenance
cost
More effective when
the transmitting and
receiving points are
along a line-of-sight
Can reach the places
which are remote
Disadvantages:
Radiate
When LASERs are used,
conversion is inefficient
Absorption loss is high
When microwaves are
used,
interference may arise
25. Recent Research
Based on RIC , Led by MIT’s Marin Soljačić
Energy transfer wirelessly for a distance just
more than 2m.
Coils were in helical shape
No capacitor was used
Efficiency achieved was around 40%
Used frequencies are 1MHz &10MHz
Intel is working on it
26. 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
27. References
“Wireless Power Transmission”, Vol No.-
45, Electronics For U –August-2013
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”
28. References(Continued……)
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
