contactless energy transfer
TRANSCRIPT
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CONTACTLESS ENERGY
TRANSFER
DEEPSHIKHA
MEL-194-2K9
M.Tech 2nd Sem
(Power system & Drives)
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Overview
Electrical wiring problem for plant or production
engineers. The advantages of portability and wireless
communication are greatly hindered by the fact
that the devices themselves must be plugged
into the walls to charge.
We need cheap and versatile wireless/
contactless energy transfer technology.
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Background
In 1856, the early days of electromagnetism,
before the electric wire grid was developed,Nikola Tesla worked towards transport of energy
over long distances without any carrier medium.
Radiative modes of Omnidirectional antennas.
Directed radiation modes using laser or highly
directional antennas.
With the invent of autonomous electronics, the
issue revisited.
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Background
Discovery of electromagnetic radiation in the
form of radiowaves. Soljai realized that instead of irradiating the
environment with electromagnetic waves, fill the
space with a "non-radiative" electromagnetic
field.
Non-radiative mid-range energy transfer based
on the principle of resonant coupling.
Energy transfer possible for small distances.
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Resonant Energy Transfer
Principle:Two same-frequency resonant objects
tend to couple, while interacting weakly withother off-resonant environmental objects.
Transmitter coils and circuitry -Coils in parallel
with a suitable capacitor.
Receiver coils and circuitry - Coils are similar of
designs are made to work at the same resonant
frequency as the primary.
Coupling - tight, loosely, over, or critical
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DC
SOURCE
FULL-BRIDGE
INVERTERTOP COIL BOTTOM
COIL
CURRENT
SENSOR
PIC
MICROCONTOLLER
GATE
DRIVERS
TRANS-
FORMER
RECTIFIER
AND FILTER
BUCK
CONVERTER
CELL PHONE
WALL
VOLTAGE
LAPTOP
AIR GAP
FEEDBACK CONTROL
DAC/VCO
BLOCK
DIAGRAM
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CET Desktops
Uses coupled resonant coils in a flat "pad" style to
transfer tens of watts to a variety ofconsumerdevices, including lamp, phone, PDA, iPod etc.
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CET Desktops - Introduction
The energy is transferred by magnetic field and
the mutual inductance between the primary andsecondary coils.
Wooden or plastic table is embedded with a
matrix of hexagon spiral windings and electronic
devices fitted with power receiving coils.
The increase in the electromagnetic coupling
between the primary and secondary coils,
allows power to be transferred.
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CET Desktops - Development
The coil design plays the most important role.
Estimate the magnetic field intensity and the selfand mutual inductances of hexagon spiral windings.
The control and commutation systems to activate
and control the currents in the windings.
Advanced issues such as communications,shielding, heating problems and stability needs to
be taken in consideration.
Optimization in the coil geometries and the circuit
allows to develop the most efficient solution.
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CET usingCurved coils andCapacitive Plates
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Curved Coils & Capacitive Plates
Researchers at MIT reported discovered an
efficient way to transfer power between coilsseparated by a few meters. Soljacic and team
extended the distance between the coils by
adding resonance to the equation.
The theory uses a curved coil of wire as aninductor. A capacitance plate, which can hold a
charge, attaches to each end of the coil. As
electricity travels through this coil, the coil
begins to resonate.
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Curved Coils & Capacitive Plates
One coil can even send electricity to several
receiving coils, as long as they all resonate atthe same frequency.
The researchers have named this non-radiative
energy transfer since it involves stationary fields
around the coils rather than fields that spread inall directions.
The setup could power or recharge all the
devices in one room.
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Benefits
Eliminate the cords and large power bricks on
the ground that make tripping hazards. Allows no wire installation and mobility in
particular area.
Maintenance free system.
Can be made without polluting the environment.
Coupling is achieved using magnetic fields so
technology is relatively safe.
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Limitations
Energy transfer is possible to short distances as
it relies on two coils in range with each other andresonating at the same frequency.
Compared to inductive transfer in transformers,
the efficiency is somewhat lower (around 80% at
short range).
Compared to non- rechargeable batteries, the
costs is hundreds times higher.
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Applications
Used to transfer energy to multiple devices for
charging purpose or powering other commonlyused household gadgets.
Industrial applications by elimination of mess
created by wires and maintenance costs.
Used to power automated freely roamingrobots.
Used as power source in surgical applications
since using wires in such areas may be
cumbersome and pose risks.
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Applications
Used for powering several lights at few feets in
industries. SEW-Eurodrive, Lyman, S.C. produce EMC
tested CET device called Movitrans, for use as
a power supply for transport systems in
logistics centers, floor conveyors, automaticallyguided vehicle systems, and conveyor trolleys.
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THANK YOU