Wireless power transmission

Presented by :-Rubima

UE114049BE-EEE( 7th sem)

Why WPT?

• One of the major issues in power system is the losses occurring during thetransmission and distribution of electrical power.

• The percentage of loss of power during transmission and distribution isapproximated as 26%.

• The main reason for power loss during transmission and distribution isthe resistance of wires used in grid.

• According to the World Resources Institute (WRI), India’s electricity gridhas the highest transmission and distribution losses in the world – awhopping 27-40%.

• Tesla has proposed methods of transmission of electricity usingelectromagnetic induction.

What is WPT?

• As the word wireless means “without wire”.

• Wireless energy transfer or wireless power is the transmission of electricalenergy from a power source to an electric load without interconnectingman made conductors.

• Wireless transmission is useful in cases where interconnecting wires areinconvenient, hazardous or impossible.

History

• Experiments performed between 1888 and 1907 by Nikola Tesla

• Started efforts on wireless transmission at 1891 in his“experimental station” at Colorado

• He lighted a small incandescent lamp by means of a resonant circuitgrounded on one end.

• William C. Brown, the pioneer in wireless power transmissiontechnology

• The idea of Tesla is taken in to research after 100 years by a teamled by Marin Soljačić from MIT

How safe is WPT?

• Human beings or other objects placed between thetransmitter and receiver do not hinder the transmission ofpower.

• Magnetic field tend to interact very weakly with thebiological tissues of the body, and so are not prone to causeany damage to any living being

Microwave Transmission

• Microwave transmission refers to the technology oftransmitting information by the use of radio waves whosewavelengths are conveniently measured in small numbers ofcentimeters; these are called microwaves.

• Radio spectrum ranges across frequencies of roughly 1.0gigahertz(GHz) to 30GHz.

• Corresponds to wavelength from 30 centimeters down to1.0cm.

Microwave Power Transfer

• Transfers high power from one place to another.

• Two places being in line of sight usually

• Steps:

~Electrical energy to microwave energy

~Capturing microwaves using rectenna

~Microwave energy to electrical energy

MPT cont…

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

Building Blocks for MWPT

• A converter for converting DC to Microwave frequency.

• Antenna for transmission of the generated microwave.

• A rectifying antenna (RECTENNA) for receiving the microwave beam and converting back into DC.

Magnetrons

A Magnetrons is a high powered vaccum tube that generates that generates non -consistent microwaves

with built in resonators or by special

oscillators or solid state devices to control the frequency.

The electromagnetic energy created from a magnetron can travel at the speed of light

Semiconductor Amplifier

It generate low power microwave with a low voltage

It is easy to control a phase and amplitude

Semiconductor device for microwave circuits are FET,HBT,HEMT.

Material for semiconductor device

• Si -lower frequency

• GaAs-higher frequency

Antennas

Antennas can be applied for both the MPT & Communication system.

Fixed target of the MPT system we use large parabolic antenna

Moving target we use phased array antenna.

SPS is designed with phased array antenna.

Rectenna

Rectifying circuit and antenna

Receive and rectify a microwave power to DC

Passive element

Ideally 100% of the received microwave power is converted to DC power

Solar Power Satellites

• Solar Power Satellites (SPS) have proposed to collect solar energy in space and beam it down to the Earth.

• Solar energy is captured using photocells

• 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

• Efficiency exceeds 95% if microwave is used.

Why use SPS ?

There is no air in space, so the satellites wouldreceive somewhat more intense sunlight, 3 timesstronger than on the surface.

unaffected by weather.The SPS concept is simpler than most power

systems here on earth. it can be collected 24 hours per day .

( since there are no clouds or night in high Earthorbit).SPS does not use up valuable surface area on the

Earth

How sps works?

Four basic steps to convert sunlight into electricity

• Capture solar energy in space and convert it to electricity

• Transform the electricity to radio frequency energy andtransmit it to Earth

• Receive the radio frequency energy on Earth and convert itback to electricity

• Provide the electricity to the utility grid

Advantages

• Efficient

• Easy

• Need 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

• Zero fuel cost

Disadvantages

• The Capital Cost for practical implementation of WPT seemsto be very high.

• Interference of microwave with present communicationsystems.

• Common belief fears the effect of microwave radiation.

• initial cost is high.

• Geosynchronous satellites would take up large sections ofspace

Applications

• Near-field energy transfer

– Electric automobile charging

• Static and moving

– Consumer electronics

– Industrial purposes

• Harsh environment

• Far-field energy transfer

– Solar Power Satellites

– Energy to remote areas

– Can broadcast energy globally (in future)

Conclusion

• Transmission without wires- a reality

• Efficient

• Low maintenance cost. But, high initial cost

• Better than conventional wired transfer

• Energy crisis can be decreased

• Low loss

• In near future, world will be completely wireless

Thanks…