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WIRELESS POWER TRANSMISSION

2.  What is wireless power transmission(WPT)?
 Why WPT?
 History of WPT
 Types of WPT
◦ Techniques to transfer energy wirelessly
 Advantages and disadvantages
 Applications
 Conclusion
 References
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3.  The transmission of power from one place to
another without using wires, cables or chords
 But, the wireless power transmission is made
possible by using various technologies like
microwaves, lasers and EM waves
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4.  As per studies, most electrical energy transfer
is through wires.
 Most of the energy loss is during
transmission
• On an average, more than 30%
• In India, it exceeds 40%
Wireless Power Transmission 4

5. History of WPT: Tesla’s Expt
 In 1899, 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.
 The efficient midrange power
transfer concept is Witricity. In
this model source and load are in
Magnetic resonance so there is no
power loss.

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CONCEPT OF ELECTROMAGNETIC WAVE:
When an electric current passes through a wire, there is an
electric field & magnetic field in the dielectric surrounding
the conductor .
The electric field of a circuit over which energy flows has
three main axes which are mutually perpendicular to each
other:
a. The magnetic field, concentric with the conductor.
b. The lines of electric force, radial to the conductor.
c. The power gradient, parallel to the conductor.

7. RESONANCE COUPLING
 A group of theoretical physicists at MIT came up with the idea to use
resonant induction to transmit power wirelessly led by Dr. Marin Soljacic.
“Resonance", a phenomenon that causes an object to vibrate when
energy of a certain frequency is applied.
The Rise Of The Fallen in 2007

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9.  Reliable
 Efficient
 Fast
 Low maintenance cost
 Can be used for short-range
or long-range.
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11.  The transfer of energy
◦ Magnetic coupling
◦ Inductive coupling
 Simplest Wireless Energy coupling is a
transformer
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Electricity
Magnetism
Electromagnetism
Magnetic
Induction
Energy/Power
Coupling
Resonance
Resonant Magnetic
Coupling

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Inductive Coupling:
 It uses magnetic fields that is produced due to current's movement
through- wire. Bending the wire into a coil amplifies the magnetic field.
The more loops the coil makes, the bigger the field will be.
 This is the principle how a transformer works.
Using it an electric toothbrush recharged. It takes three basic steps:
1. Current from the wall outlet flows through a coil inside the
charger, creating a magnetic field. In a transformer, this coil is called
the primary winding.
2. When you place your toothbrush in the charger, the magnetic field
induces a current in another coil, or secondary winding, which
connects to the battery.
3. This current recharges the battery.

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Need of Resonant coupling:
Non-resonant coupled inductors(transformers,)work on the
principle of inductive coupling is of short range power transfer &
requires a magnetic core. Over greater distances the NRI Method is
highly inefficient and wastes the majority of the energy in resistive
losses of the primary coil.
Hence concept of resonant coupling comes where two coils are
tuned to a particular frequency called resonating frequency &
absorb optimal energy.

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Comparison with other technologies:
In conventional transformers, for inductive transfer
efficiency around 80% at short range
 in witricity tightly coupled conventional transformers
has efficiency around 90-95% .
In addition, where batteries need periodic maintenance
and replacement, resonant energy transfer can be used
instead. So pollution due to Batteries during their
construction and their disposal is largely avoided.

19.  Will it harm me?
 Will it harm the environment?
 Will it interfere with important
communication?
NO

20.  No wires
 No e-waste
 Need for battery is
eliminated
 Efficient energy
transfer
 Harmless, if field
strengths under
safety levels
 Maintenance cost is
less
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21.  Distance constraint
 Field strengths have to be under safety levels
 Initial cost is high
 In RIC, tuning is difficult
 High frequency signals must be the supply
 Air ionization technique is not feasible
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25.  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
Wireless Power Transmission
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 “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”
 Wikipedia.
 EFY posted articles on WPT.

27. Wireless Power Transmission
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