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Wireless Power Transmission

(WPT)

Presented By:SHAILIE RAI

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OVERVIEWIntroduction to Wireless Power Transmission

(WPT)Need of WPTHistory of WPT Varieties of WPTAdvantages and DisadvantagesApplicationsFuture ScopeReference

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Introduction to WPT Efficient transmission of

electric power from one point to another through vacuum or an atmosphere without the use of wire or any other substance.

WPT can transport power to locations, which are otherwise not possible or impractical to reach.

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• Wireless Charging Pad (WCP)

• Electric automobile charging

• Wireless charging of Gadgets

• Solar Power Satellites

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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 than 30%• In India, it exceeds 40%

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Reliable

Environmentally Sound

Efficient

Low Maintenance

Cost

Can be Used for short-range or

long-range

WHY

WPT?

Need of WPT

History of WPT In 1897 Nikola Tesla pioneer

of induction techniques, had a vision for “World Wireless System”.

A 187 feet tall tower was built to broadcast energy

So that all people can have access to free energy.

He managed to light 200 lamps from a distance of 40km.

Figure : Tesla's colorado springs lab

Block diagram of a wireless energy transfer system

Source Electronics

AC/

DC

DC/RF Amplifier

IMN Source Resonator

Device Resonator

IMNRF/DC Rectifier

Load

AC Mains

Impedance Matching Networks

Device Electronics

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Varities of WPT

WPT

Near-field techniques

Inductive Coupling

Resonant Inductive Coupling

Far-field techniques

Microwave Power Transmission

(MPT)

LASER power transmission

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Inductive coupling

Primary and secondary coils are not connected with wires.

Energy transfer is due to Mutual Induction

Example : Transformer, Wireless Charging Pad (WCP), electric brushes.

On a WCP, the devices are to be kept, battery will be automatically charged.

Figure : Inductive Coupling

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The charging pad (primary coil) and the device(secondary coil) have to be kept very near to each other.

It is preferred because it is comfortable.

Less use of wires.

Figure : Wireless Charging Pad

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Resonant Inductive Coupling (RIC)

Combination of inductive coupling and resonance.

Resonance makes two objects interact very strongly.

Inductance induces current.

Figure : Resonance Inductive Coupling (RIC)

Witricity This project is based on RIC. It was led by MIT team. In this project the energy was

transferred wirelessly for a distance just more than 2m.

Efficiency achieved was around 40%

Researches for decreasing the field strength and to increase the range are in progress.

Figure : Witricity (Wireless Transmission of

Electricity)

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RIC vs. inductive coupling

RIC is highly efficient.RIC has much greater range than inductive

coupling.RIC can be one-to-many. But usually inductive

coupling is one-to-one.Devices using RIC technique are highly

portable.

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Advantages of near-field techniques

No wires No e-waste Need for battery is

eliminated Efficient energy transfer

using RIC Harmless, if field

strengths under safety levels

Maintenance cost is less

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Disadvantages of near-field techniques

Distance constraint

Field strengths have to be under safety levels

Initial cost is high

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Far-field energy transfer

It aims at high power transfer.It can be a laser or microwave

transmission.It needs line-of-sight.It is radiative in nature.

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Microwave Power Transmission (MPT)

Transfers high power from one place to another. Two places being in line of sight usually.

A complete microwave transmission system (MPT) consists of 3 essential parts:

Electrical power to microwave power conversion.

Absorption antenna that captures the waves.

Reconversion to electrical power.Figure : Microwave Transmitter

and Rectenna

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AC can not be directly converted to microwave energy.

AC is converted to DC first.DC is converted to microwaves using magnetron.Transmitted waves are received at rectenna which

rectifies, gives DC as the output.DC is converted back to AC.

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LASER transmission

LASER is highly directional, coherent.Not dispersed for very long.But, gets attenuated when it propagates

through atmosphere.Simple receiver - Photovoltaic cellCost-efficient

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SolarPower Satellites (SPS)

To efficiently make use of renewable energy i.e., solar energy.

SPS are placed in geostationary orbits.

Solar energy is captured using photocells.

Figure : Space Solar Power satellite

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Each SPS may have 400 million photocells.

Transmitted to earth in the form of microwaves/LASER.

Using rectenna/photovoltaic cell, the energy is converted to electrical energy.

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Rectenna

Stands for rectifying antennaConsists of mesh of dipoles and diodesConverts microwave to its DC equivalent

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Rectenna in US

Rectenna in US receives 5000MW of power from SPS.

It is about one and a half mile long.

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Projects based on WPT

In 1993 a project was presented about wireless power supply in Alaska named "Alaska'21”.

The system used for this project consisted of a 2.45 GHz phased array design. The distances that should be bridged are between 1 and 15 miles.

Figure : Alaska’21

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The Grand Bassin project lead by the local university will supply electricity to a remote isolated mountain village.

A prototype was build and presented at the Wireless Power Transmission conference in 2001, which was held on the island.

Figure : Grand Bassin– La Reunion

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In May 2008, a long-range WPT demonstration was realized on one of the islands of Hawaii.

It involved transmission of wireless energy over a distance of 148 kilometers.

Figure : Hawaii demonstration

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Advantages of far-field techniques

EfficientEasyNeed for grids, substations etc are eliminated.Low maintenance cost.More effective when the transmitting and

receiving points are along a line-of-sight.Can reach the places which are remote.

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Disadvantages of far-field techniques

Radiative Needs line-of-sight Initial cost is high When LASERs are used,

conversion is inefficientAbsorption loss is high

When microwaves are used, interference may ariseFried Bird effect

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Applications

Near-field energy transfer– Electric automobile charging

• Static and moving– Consumer electronics– Industrial purposes

Far-field energy transfer– Solar Power Satellites– Energy to remote areas– Can broadcast energy globally (in future)

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Future Scope

In future transmission will be without wires.It would be more efficient.Low maintenance cost but high initial cost.Better than conventional wired transfer.Energy crisis can be decreased.Low power loss. In near future, world will be completely

wireless.

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Reference http://www.leonardo-energy.com/sites/leonardo-

energy/files/root/pdf/2009/WirelessPower.pdf S. Sheik Mohammed, K. Ramasamy, T.

Shanmuganantham,” Wireless power transmission – a next generation power transmission system”, International Journal of Computer Applications (0975 – 8887) (Volume 1 – No. 13)

http://www.witricity.com/assets/highly-resonant-power-transfer-kesler-witricity-2013.pdf

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THANK YOU