This document provides an overview of wireless power transmission (WPT) including its history, types, techniques, advantages, disadvantages and applications. It discusses witricity, which is wireless electricity through inductive coupling or resonant inductive coupling. The document outlines different near-field techniques like inductive coupling, resonant inductive coupling and air ionization as well as far-field techniques like microwave power transmission and laser power transmission. It provides details on technologies like wireless charging pads, rectennas and solar power satellites. In conclusion, it states that wireless transmission of energy is now a reality and can help reduce energy losses and crisis.

1. Submitted To:- Submitted By:-
Mrs Purnima (Lecturer) Akshay Parmar
Ms Neha Malik (Lecturer) (1509160)
ECE-1

2. Overview
 What is wireless power transmission(WPT)?
 Why is WPT?
 History of WPT
 Types of WPT
 Techniques to transfer energy wirelessly
 Advantages and disadvantages
 Applications
 Conclusion
 References

3. What is witricity?
 Witricity is nothing but wireless electricity.
 Transmission of electrical energy from one object to another
without the use of wires is called as Witricity.
 Because of Witricity some of the devices won't require batteries to
operate.
 But, the wireless transmission is made possible by using various
technologies.

4. • 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%
• Reliable, Efficient and Fast
• Low maintenance cost and can be used for short-range or long-
range.
Why not wires?

5. History
In 1891, Sir Nikola Tesla Proposed a method of Wireless Power
Transmission.
Tesla was able to transfer energy from one coil to another coil.
The 187 feet tall tower to broadcast energy.
Due to shortage of funds, tower did not operate
He managed to light 200 lamps from a distance of 40km.
The idea of Tesla is taken in to research after 100 years by a team led by
Marin Soljacic from MIT. The project is named as ‘WiTricity’.

6. Energy Coupling
 The transfer of energy is done through
 Mutual-inductive coupling
 Simplest Wireless Energy coupling is a transformer.

7. Types and Technologies of WPT
 Near-field techniques
 Inductive Coupling
 Resonant Inductive Coupling
 Air Ionization
 Far-field techniques
 Microwave Power Transmission (MPT)
 LASER power transmission

8. Inductive coupling
 Primary and secondary coils are not connected with wires.
 Energy transfer is due to Mutual Induction (e.g.- Transformer)
 Wireless Charging Pad(WCP),electric brushes are some examples
 On a WCP, the devices are to be kept, battery will be automatically
charged.

9. Resonance Inductive
Coupling(RIC)
 Combination of inductive coupling and resonance.
 Resonance makes two objects interact very strongly and Inductance
induces current.
 Coil provides the inductance and Capacitor is connected parallel to
the coil.
 Radiation loss will be negligible.

10. WiTricity
 Based on RIC and led by MIT’s Marin Soljacic.
 Energy transfer wirelessly for a distance just more than 2m.
 Coils were in helical shape and no capacitor was used.

11. WiTricity now…
 No more helical coils and Researches to increase the range.
 Companies like Intel are also working on devices that make use of RIC.

12. Air Ionization
 Toughest technique under near-field energy transfer techniques.
 Air ionizes only when there is a high field of 2.11MV/m.
 Natural example: Lightening.
 Not feasible for practical implementation.

14. Far-field energy transfer
 Needs line-of-sight.
 Aims at high power transfer through LASER or microwave
transmission.

15. Microwave Power Transfer(MPT)
 Transfers high power from one place to another. Two places being in
line of sight usually
 Frequency 2.45 GHz and 5.40GHz microwave beam.
 Steps:
 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

16. Rectenna
“An antenna comprising a mesh of dipoles and diodes for
absorbing microwave energy from a transmitter and converting it
into electric power.”
 Microwaves are received with 95% efficiency.
 Around 5km across (3.1 miles)
 95% of the beam will fall on the rectenna.
There are two different design types being looked at:
-Wire mesh reflector
-Magic carpet

17. 5,000 MW Receiving Station (Rectenna) in US.
This station is about a mile and a half long.

18. LASER Transmission
 LASER is highly directional, coherent
 Not dispersed for very long
 But, gets attenuated when it propagates through atmosphere
 Simple receiver
 Photovoltaic cell
 Cost-efficient
Limitations:-
 Range of 10% to 20% efficiency and high attenuation losses.
 Conform to limits on eye and skin damage

19. Solar Power Satellites (SPS)
 To provide energy to earth’s increasing energy need and efficiently
make use of renewable energy i.e., solar energy.
 SPS are placed in geostationary orbits.
 Solar energy is captured using photocells where 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.

21. Pros
 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
Cons
 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

22. 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

23. THANK YOU!!