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Introduction
Wireless electricity or witricity is
the transfer of electric energy or
power over a distance without the
use of wires.
In order for the energy to be
transferred safely coupled resonators
are used.
Coupled resonators are two objects
of the same resonant frequency that
exchange energy efficiently without
much leakage .
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Transmitter Section:
DC power Source: Step-Down transformer, rectifer circuit convert that
AC voltage to DC signal
Oscillator Circuit: Royer Oscillator(achieve a high oscillating current for
the transmitter coil).
Transmitter Coil: L= d2n2/(l+0.45d)
The operating frequency of the oscillator is determined
by the resonance formula given below
F = ½ × π × √ (LC)
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Receiver Section:
Receiver coil:
Rectifier circuit and a voltage regulator IC: LM 7805 voltage regulator IC
The rectifier circuit in the receiver section converts this AC voltage in to DC
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METHODS USED FOR WIRELESS POWER
TRANSMISSION
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Far Field Electricity Transmission Radio/Microwave Power transmission Laser Power Transmission Near Field Electricity Transmission Inductive Charging Evanescent/Resonant Wave Coupling
INDUCTION (INDUCTIVE COUPLING):
• The simplest example for wireless energy transfer using this method is the electrical
transformer.
• The main drawback of this method is the short range.
• A larger, stronger field can be used for energy transfer over large distance, but this
process is extremely inefficient. Since magnetic field spreads in all direction, making
a large wastage of energy.
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Power is transmitted when the coils have same resonant frequency.
By using resonant induction one coil can send electricity to several receiving coils as long as they all resonate at same frequency.
Resonance : It is the tendency of a system to oscillate with larger amplitude at some frequencies than at others.
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Why not wires??
As per studies, most electrical energy transfer is through wires.
Most of the energy loss is during transmission
On an average, more than30%
In Pakistan, it exceeds by 40%
Why not batteries?? Estimated that 40 billion
batteries per year add to the
e-waste burden. And of course its
not a good sign.
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Advantages and Hurdles
It can do away with costly grids and substations.
Homes and cities can be provided power wireless from a central transmission point.
Battery operated devices will never run out of power.
we can have cars that run non-stop with full battery charge.
We will never have to go to charging station.
Aircraft can fly nonstop with no need to refuel.
The future highway could have inductive coils imbedded in the road.
Hurdles/ Disadvantages: Biological Drawbacks (line of sight of microwave and Laser signal).
Economic cost.
Less efficiency.
Short distance.(2cm)
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Scope
01/12/201412
no need of power cables.no need of charging batteries, orbuying new batteries for yourelectrical gadgets.
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References:
A next generation power transmission system”, International Journal of Computer Applications (0975 – 8887) (Volume 1 – No. 13)
Witricity
Peter Vaessen,” Wireless Power Transmission”, Leonardo Energy, September 2009 11/2/14 Wireless Power
www.wikipedia.com
http://www.sciencedirect.com/science/journals
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