contactless energy transfer

8/7/2019 contactless energy transfer

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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

contactless energy transfer

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