Wireless power transmission involves transferring electric power from a power source to devices without wires. There are two main techniques: near-field techniques like inductive coupling and resonant inductive coupling, which work over short distances; and far-field techniques like microwave and laser transmission, which can transmit power over longer distances. While offering wire-free charging, wireless power also faces challenges of safety, efficiency, and cost that need to be addressed for practical applications.

1. VAST CONCEPET SIMPLY EXPLAINED
WIRELESS POWER TRANSMISSION
Ahmad Ziyad
Computer Engineering
University Of Mosul , Iraq

2. Overview
What is wireless power transmission(WPT)?
.History of WPT
Why WPT?
Types and Techniques of WPT.
.- Advantages and disadvantages
Challenges of WPT.
.Applications
Simple experiment on inductive coupling.
.Conclusion

3. What is WPT?
One of the major drawbacks in current power distribution
system is the losses during the transmission of electrical
energy. As the demands of power are increasing
conveniently, power generation also increases and this
leads to increase power loss during transmission. Our
present transmission system is only 70-74% efficient this
means about 1/3 of our generated power is waste in
distribution.
Now-a-days global scenario has been changed a lot and
there is tremendous development in every field. So we have
to keep pace for development of new power technology.
The transmission of power without wires may be one noble
alternative for electricity transmission.

4. What is WPT (cont..)
The definition of Wireless Power Transmission (WPT) can
be given as a way of efficient transmission of electric
power from one point to another through
vacuum or an atmosphere without the use of wires or any
other substances.

5. History
Nikola Tesla , Croatian inventor, electrical engineer,
mechanical engineer, physicist ,futurist and
pioneer of induction techniques.
In 1893, he made pronouncements on the possibility
of wireless communication with his devices.
Tesla tried to put these ideas to practical use in his
unfinished Wardenclyffe Tower project, an intercontinental
wireless communication and power transmitter,
but ran out of funding before he could complete it

6. History (contd…)
Tesla was able to transfer energy from
one coil to another coil
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 Soljačić from MIT. The
project is named as „WiTricity‟.

7. Why WPT?
Reliable
Efficient
Fast
Low maintenance cost
Can be used for short-range or
long-range.

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

9. Inductive coupling :
The basic concept behind electromagnetic approach of WPT
is magnetic induction between two coil ,say transmitting and receiving coil.
When transmitter coil is excited, it generates flux and when
receiver coil receives this flux a potential difference is developed
across its terminals.
The potential difference developed in receivers is directly related to
distance between transmitter and receiver coil . Examples for this method
are Transformers and Wireless Charging Pad.
Fig.1 shows the basic model for WPT.
its efficiency is very poor and
cannot be used for
large distance transmission.

10. Inductive Coupling: (contd..)
In order to transmit power for long distance using this method
we have to introduce intermediate coils between
transmitter and receiver as shown in the figures below.

11. Resonance Inductive Coupling (RIC) :
What is electric resonance ?
Resonance of a circuit involving capacitors and inductors occurs because the collapsing
magnetic field of the inductor generates an electric current in its windings that charges
the capacitor, and then the discharging capacitor provides an electric current that builds
the magnetic field in the inductor. This process is repeated continually, Resonant circuits exhibit
.ringing and can generate higher voltages and currents than are fed into them
So RIC is a phenomenon with inductive coupling where the coupling becomes
stronger when the "secondary" (load-bearing) side of the loosely coupled coil
resonates.
.Coil provides the inductance
.Capacitor is connected parallel to the coil
Energy will be shifting back and forth between magnetic field surrounding
.the coil and electric field around the capacitor
.Radiation loss will be negligible

12. RIC vs. inductive coupling
.RIC is highly efficient
RIC has much greater range than
.inductive coupling
RIC is directional when compared to
.inductive coupling
RIC can be one-to-many. But usually
.inductive coupling is one-to-one
Devices using RIC technique are
.highly portable

13. WiTricity:
The term WiTricity was used for a project that took place at MIT, led by
Marin Soljačić in 2006.
The MIT researchers successfully demonstrated the ability to power a 60 watt
light bulb wirelessly, using two 5-turn copper coils of 60 cm (24 in) diameter,
that were 2 m (7 ft) away, at roughly 45% efficiency. The coils were designed
to resonate together at 9.9 MHz (wavelength ≈ 30 m) and were oriented along
the same axis as shown in fig 1.
One was connected inductively to a power source, and the other one to a bulb.
The setup powered the bulb on, even when the direct line of sight was blocked
using a wooden panel as shown in fig 2.
Researchers were able to power a 60 watt light bulb at roughly 90%
efficiency at a distance of 3 feet.
The research project was spun off into a private company, also called WiTricity.

14. WiTricity
Fig 1
Fig 2

15. Advantages of near-field techniques :
.No wires
.Almost no electricity waste
.Need for battery is eliminated
.Efficient energy transfer using RIC
.Harmless, if field strengths under safety levels
Maintenance cost is less.

16. 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 applied.

17. Far-field Techniques :
Radiative.
Needs line-of-sight.
LASER , microwaves and Air Ionization.
Aims at high power transfer.
Tesla’s tower was built for this based
on this technique.

18. :Microwave Power Transfer(MPT)
Transfers high power from one place to another using Microwaves. Two places
being in line of sight usually.
A block diagram of the demonstration components is shown
microwave source, a transmitting antenna, and a receiving rectenna.
The microwave source is of a high power handling capability.
A rectifying antenna called a rectenna receives the transmitted power and
converts the microwave power to direct current (DC) power. This demonstration
rectenna consist of 6 rows of dipoles antennas where 8 dipoles belong to
each row. Each row is connected to a rectifying circuit which consists of low pass
filters and a rectifier. The rectifier is a Schottky barrier diode that is impedance
matched to the dipoles by a low pass filter.
The 6 rectifying diodes are connected to light bulbs for indicating that the
power is received. The light bulbs also dissipated the received power.
This rectenna has a 25% collection and conversion efficiency, but retinas have
been tested with greater than 90% efficiency at 2.45 GHz.

19. The figure demonstrates the wireless power transfer
.process through microwaves
A rectenna

20. LASER :
Basic theory behind wireless power transmission by LASER is to convert electricity into
laser beam which point to receiver made up of photovoltaic cell.
This mechanism is known as "power beaming". In principle, all lasers can be used for transmitting
power. The longest distance between emitting and receiving points achieved so far is in the
order to hundred kilometers. The largest amount of energy transmitted so far was during an
experiment by the US Jet Propulsion Laboratory in 1975, when 30 kW were transmitted from
a 26 m diameter parabolic dish to a 1.54 km distant rectenna with 85% efficiency .
In 2002 and 2003, Steinsiek and Schoafer demon started ground to ground wireless power
Transmission via laser to a small, otherwise fully independent rover vehicle equipped with
photovoltaic cells as a first step towards the use of this technology for powering airships
and further in the future lunar surface rovers.

21. LASER vs. MPT
When LASER is used, the antenna
.sizes can be much smaller
Microwaves can face interference (two
frequencies can be used for WPT are
.2.45GHz and 5.4GHz)
LASER has high attenuation loss and
also it gets diffracted by atmospheric
.particles easily

22. Air Ionization
Toughest technique among energy transfer techniques.
Air ionizes only when there is a high field.
Needed field is 2.11MV/m.
Natural example: Lightening.
Not applicable for practical implementation.

23. Advantages of far-field techniques :
transmits wireless power to any distance without limit.
The efficiency of the transmission can be as high as 96 or 97
per cent, and there are practically no losses.
Need for grids, substations ,cables, is eliminated.
.Low maintenance cost
More effective when the transmitting and receiving
points are along a line-of-sight.
There are areas of the world where the need for electrical
power exists, yet there is no method for delivering power.
Africa is in need of power to run pumps to tap into the vast
resources of water under the Sahara Desert.
Rural areas, such as those in China, require the electrical
power necessary to bring them into the 20th century and to equal standing
with western nations. The wireless transmission will solve many of
these problems.

24. Disadvantages of far-field Techniques :
Radiation.
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
.◦ Its Bio-Effects on human and animals

25. Applications
Near-field techniques :
◦ Electric automobile charging
.Static and moving
.◦ Consumer electronics
◦ Charging of Devices like phones , PC’s.. Etc…
How does Wireless Charging work ?
It’s the process of electrically charging battery-powered devices and
equipment without the need for a wired electrical power connection.
Wireless charging can be done by three different techniques:

26. Inductive Charging: Uses electromagnetic waves to transfer energy and charge
devices wirelessly. it requires the device to be placed on a conductive charging
pad/equipment, which is directly connected to a wall socket.
It is mainly used to charge small hand-held devices such as, smartphones,
PDAs and mobile phones. The devices must be compatible with Qi standard
Which is an open interface standard that defines wireless power transfer
over distances of up to 4 cm , and is developed by
the Wireless Power Consortium.
Resonance Charging: Used for charging large devices and equipment such as
laptops, robots, cars and more.
It consists of a sending (sender) copper coil and a receiving (receiver) copper coil
at the device end. The sender and receiver must configure the same electronic
magnetic frequency to transfer electrical energy.

27. Radio Charging: Similar to inductive charging, radio charging use wireless radio
waves to transfer energy to small devices and equipment.
A Radio Frequency (RF) system, similar to a Wi-Fi system, delivers safe
wire-free charging energy at a distance of up to 5m (15ft) from a transmitter to
a receiver device, such as a mobile phone, and maintains charging while the
receiver is in motion.

28. Far-field techniques :
Remote transmission of energy for space applications.
Remote powering of unmanned aircrafts, vehicles, robots.
Controlling the destructive storms, e.g. the path of hurricane.
Remote powering of wireless sensors, especially for sensors
.located in hard-to-reach environment
Remote charging of bio-implanted devices.
SPS).)Solar Power Satellites

29. Solar Power Satellites
If an efficient method of wireless power transmission is developed,
one possible application would be a solar power satellite.
This idea consists of having a satellite with solar panels orbiting the earth.
the satellite generates electrical energy using its solar panels.
This energy is encoded into suitable means and transmitted wirelessly to receivers (Rectennas) on the earth.
The receivers then decode the transmitted energy back into usable electrical power.
To demonstrate technical feasibility, researchers would first like to transmit kilowatts
of power from a satellite in Low-earth orbit.
Additionally, target 80% conversion efficiency is desired within
both the transmitter and the receiver. Since the satellite orbits
above the atmosphere, it would consistently collecting solar
energy, as opposed to photovoltaic systems on earth which
may be obstructed by weather conditions. Also, a single
satellite could potentially provide power to many locations
around the world by having multiple wireless power receivers
linked to the satellite . Thus, the development of solar power
satellites could consistently provide clean energy
.around the world

30. Rectennas:
Microwaves broadcast from SPS would be received with about 85%
efficiency. Rectennas would be several kilometers across . corps and
farm animals could be raised under it, since the thin wires used only
slightly reduce sunlight. For best efficiency, the satellite antenna
would be between 1 and 1.5 kilometers in diameter and the ground
rectenna around 14 by 10 kilometers . this would allow
The transfer of 5 to 10 gigawatts of power.
Rectenna in US receives
5000MW of power
from SPS.

31. Remote Powering of a Helicopter :
Microwave-powered helicopter flying 18 meters above transmitting antenna.
10 hr sustained flight was achieved in 1964.
Actual rectenna used on the helicopter

32. :Challenges of WPT
Technical Issues:
Beam-forming antennas for directed microwave beam.
High efficiency microwave power source (transmitter).
.High efficiency microwave rectifier (receiver)
.All have to be lightweight to reduce deployment cost
:Environmental Issues
.Safety concern
.Ecological effect
:Economic Issues
Cost of the system.
Cost of the development.
.Cost of the deployment

33. Simple experiment on inductive coupling

35. CONCLUSION
The transmission of power without wires is not a theory, it is now a reality.
The electrical power can be economically transmitted without wires to any
terrestrial distance. Many researchers have worked and established in numerous
observations, experiments and measurements, qualitative and quantitative.
Dr.N.Tesla is the father of this invention. Wireless transmission of electricity
have tremendous merits like high transmission integrity and Low Loss
(90 – 97 % efficient) and can be transmitted to anywhere in the globe and
eliminate the need for an inefficient, costly, and capital intensive grid of cables,
towers, and substations. The system would reduce the cost of electrical energy
used by the consumer and get rid of the landscape of wires, cables, and
transmission towers. It has negligible demerits like reactive power which was
found insignificant and biologically compatible. It has a tremendous economic
impact to human society. Many countries will benefit from this service.
Monthly electric utility bills from old-fashioned, electrified wire-grid delivery
services would obsolete.

36. THE END