1. Wireless power transmission

2. What is WPT?
The transmission of energy from one place to another without using wires
Conventional energy transfer is using wires
But, the wireless transmission is made possible by using various technologies
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Wireless Power Transmission

3. Why WPT? Reliable Efficient Fast Low maintenance cost
Can be used for short-range or long-range.
Wireless Power Transmission
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4. INTRODUCTION
Scientists have known for nearly two centuries that it is possible to transfer an electrical current from one coil of wire to another without them touching.
Electromagnetic induction is used in power transformers and electric motors around the world, the breakthrough came when dr soljacic realised there was another way of transferring energy through the air.
When he done an experiment by filling a room with a 'non-radiative' electromagnetic field, Most objects such as people, desks and carpets is unaffected by the electromagnetic field. But any objects designed to resonate with the electromagnetic field would absorb the energy.

5. HISTORY
As wireless technologies were being developed during the early 1900s, researchers further investigated these different wireless transmission methods.
The goal was simply to generate an effect locally and detect it at a distance.
William C. Brown demonstrated in 1964 on the CBS Walter Cronkite news a microwave-powered model helicopter that received all the power needed for flight from a microwave beam.
Between 1969 and 1975 Bill Brown was technical director of a JPL Raytheon program that beamed 30 kW over a distance of 1 mile at 84% efficiency.

6. Types and Technologies of WPT
Near-field energy transfer
Far-field energy transfer
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Wireless Power Transmission

7. Resonance and Wireless Power
Household devices like chargers produce small magnetic fields. A larger, stronger field could induce current from distance but the process is inefficient,since magnetic field spreads in all directions.
The team, led by Marin Soljacic, theorized that they could extend the distance between the coils by adding resonance to the equation.
We can understand resonance in terms of sound.The frequency at which the objects like trumpet naturally vibrates is its resonant frequency.

8. It's easy to get objects to vibrate at their resonant frequency and difficult to get them to vibrate at other frequencies. For example trumpet.
Induction can take place differently
if the electromagnetic fields around
the coils resonate at same frequency.
Capacitance plate holds charge
and attaches to each end of the coil.
As electricity travels through this
coil it begins to resonate. Its resonant
frequency is a product of the
inductance of the coil and the
capacitance of the plates.

9. The system relies on two coils
The system relies on two coils. Electricity, traveling along an electromagnetic wave tunnels from one coil to the other as long as they both have the same resonant frequency.
According to researchers, one
coil can send electricity to
several receiving coils, as long
as they all resonate at the same
frequency, so they named this as
Non Radiative Energy Transfer.
The MIT team's work suggests that this kind of setup could power or recharge all the devices in one room and modifications are necessary to send power over long distances.

10. An example
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11. 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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12. Disadvantages Distance constraint
Field strengths have to be under safety levels
Initial cost is high
In RIC, tuning is difficult
High frequency signals must be the supply
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Wireless Power Transmission

13. Far-field energy transfer
Radiative
Needs line-of-sight
LASER or microwave
Aims at high power transfer
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14. Long-distance Wireless Power
Induction generally sends power for short
distances , some plans for wireless
power involve moving electricity over a
span of miles. Few proposals involve
sending power to the Earth from space.
Unmanned plane, Stationary High Altitude Relay Platform (SHARP), was designed as a communications relay.
It fly’s in circles two kilometers in diameter at an altitude of about 13 miles , it can fly for months at a time this is because of a ground-based microwave transmitter and a disc-shaped rectifying antenna(rectenna).

15. Rectenna Stands for rectifying antenna
Consists of mesh of dipoles and diodes
Converts microwave to its DC equivalent
Usually multi-element phased array
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16. 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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17. Rectenna are central to many wireless power transmission theories, made an array of dipole antennae, which have positive and negative poles.
Microwaves produce tens of thousands of receivers on Earth would capture this energy, and rectennae would convert it to electricity.
Microwaves pass through the atmosphere easily, and rectennae rectify microwaves into electricity very efficiently. Such a setup could provide a clean source of power.

18. Advantages of far-field energy transfer
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
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19. Disadvantages of far-field energy trasnfer
Radiative
Needs line-of-sight
Initial cost is high
When LASERs are used,
conversion is inefficient
Absorption loss is high
When microwaves are used,
interference may arise
FRIED BIRD effect
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20. Applications Near-field energy transfer Far-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)
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21. 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
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23. QUERIES