DEPARTMENT OF

ELECTRICAL AND

ELECTRONICS ENGINEERINGEEE NMIT 20141

WIRELESS POWER TRANSFER

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overview

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What is wireless power transfer

History

Why not wires..?

Why wireless…?

Principle

Methods of WPT

Merits and demerits

Biological Impact

Application

Conclusion

Reference

What is Wireless power transfer

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The transmission of energy from one place to

another without using wires.

Solution is WiTricity.

WPT emerges out as the best alternative for

efficient power transmission.

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HISTORY Nikola Tesla -Pioneer of induction techniques

His vision for “World Wireless System”

In 1894 Nikola Tesla used resonant inductive coupling, also

known as "electro-dynamic induction" to wirelessly light up

incandescent lamps .

1897 he patented a device called

high-voltage resonance transformer or"Tesla coil” capable of

producing

very high voltagesat high frequency.

In 1899 - an aerial tower called Wardenclyffe .

which was meant to be a pilot plant for his “World Wireless

System” to broadcast energy around the globe.

The idea of Tesla is taken in to research after 100 years in 2007.

Nikola Tesla (1856 - 1943)

Why Not Wires ?

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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%

Risk of electrical hazards

Complicated wiring structure

Maintenance cost is high.

Why wireless…?

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Reliable

Efficient

Fast

Low maintenance cost

Can be used for short-range or long-range.

Method Of WPT

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There are mainly 5 method to transfer power

Inductive Coupling

Air Ionization

LASER power transmission

Resonant Inductive Coupling

Microwave Power Transmission (MPT)

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Short range – INDUCTIVE COUPLING, AIRIONIZATION

LASER POWER TRANSMISSION

Medium range – RESONANT INDUCTION

Long range power transfer – MICROWAVE POWER

TRANSMISSION

For the application of

Inductive coupling

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The principle of mutual induction between two coils

can be used for the transfer of electrical power.

The simplest example is

transformer

where there is no physical contact

between the primary and the secondary

coils

Air ionization

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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

Laser power transmission

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LASER is highly directional, coherent

Simple receiver

Photovoltaic cell

Cost-efficient

Not suitable for very long

gets attenuated when it propagates through

atmosphere

Need of Resonance coupling

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transformers work on the principle of inductive coupling, short range power transfer & requires a magnetic core.

Over greater distances this method is highly inefficient and wastes the majority of the energy in resistive losses of the primary coil.

concept of resonant coupling comes where two coils are tuned to a particular frequency called resonating frequency & absorb optimal energy.

Resonant inductive coupling

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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.

BLOCK DIAGRAM RIC

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RIC continue…..

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This wireless power transmission concept based on strongly-coupled resonator.

Time taken for energy transfer is less than the time of loss . So high efficiency.

Since the resonant wavelength is much larger than the resonators, the field not need of line-of-sight.

This method is safe, since magnetic fields interact weakly with living organisms..

Microwave Power

Transfer(MPT)

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In this method Electrical energy is converted to microwave energy.

AC is converted to DC first then this DC is converted to microwaves using magnetron.

This wave is Captured using rectenna and convert Microwave energy to electrical energy.

THIS Methord is used where transfers high power from one place to another being in line of sight usually.

MPT(Continued….

)

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Rectenna:

Transmitted waves are received at rectenna.

Consists of mesh of dipoles and diodes

Converts microwave to its DC equivalent

DC is converted back to AC

Usually multi-element phased array

Eg. Solar power satellite

Solar Power

Satellite

Merits of WPT

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Eliminates the existing transmission line cables, towers and sub stations

More freedom of choice of both receiver and transmitters

Cost of transmission and distribution become less.

Power could be transmitted to the places where the wired transmission is not possible.

Loss of transmission is negligible level.

Safer by eliminating the sparking hazard.

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More Reliable/Less Costly- Never run out of battery power in wireless zones

- Power transfers more efficiently than through wires

More Convenient- No more changing batteries

- No messy cords to carry.

Environmentally Friendly- Reduces the use of disposable batteries

- Reduces energy loss

Demerits

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The Capital Cost for practical implementation of WPT seems to be very high.

Interference of microwave with present communication systems

Common belief fears about the effect of microwave radiation among peoples

When LASERs are used,

conversion is inefficient

Absorption loss is high

Biological Impact

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Institute of Electrical and Electronic Engineers

(IEEE) and by the International Commission on Non-

Ionizing Radiation Protection (ICNIRP).

Experimently prooved that

no radio frequency (RF) electromagnetic fields

causes cancer,

but there is a very small increase a person’s body

temperature or may heat body tissues and may

stimulate nerve and muscle tissues.

Is WiTricity Secure ?

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Principle is based on Magnetic Waves.

The question is if Magnetic Waves Secure ?

The answer is we all live in a globe that has already

surrounded by magnetic waves.

Yes it is secure !

Applications

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Wireless electricity can be used to power or recharge:

1:Electric Cars

2,Used to charge Electrical and Electronics gadgets

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Mobile phones ,laptops, television,

Schematic representation of the functional benefits of wireless

energy transfer based on HR-WPT.

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3, Medical Devices

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Pictures showing two examples of HR-WPT charging

applications in medical

devices: Left ventricular assist device (LVAD) (left)

and pacemakers (right).

4,home electrification

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6, Led lighting

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LED (light emitting diode) lights can be directly powered with

wireless electricity ,which eliminate

the need for batteries enabling architectural lighting

designers to create products that seemingly float in mid-air,

with no power cord.

Defense Systems

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Photographs showing several military applications for

highly resonant wireless

charging systems: military robots (left) and soldier

electronics (right).

Future of WiTricity

Think that the city will be covered with WiTricity hot

spots like wi-fi.

which eliminate need of charging batteries or carrying

adapters all around !

Transport system become wirelessly powered

which eliminate fuel engines.

Which will give rise to the Robotic Technology

they will work for us 24 H 365 days without any

failure.31 EEE NMIT 2014

Conclusion

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Transmission without wires- a reality

Efficient

Low maintenance cost. But, high initial cost

Better than conventional wired transfer

Energy crisis can be decreased

Low energy wastage

In near future, world will be completely

wireless

Reference

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Highly Resonant Wireless Power Transfer:

Safe, Efficient, and over Distance by Dr. Morris Kesler

WiTricity.“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”

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

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Thanks For

Listening…………….!!!

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