This document presents an overview of wireless power transfer techniques. It discusses the background and history of wireless power, including early experiments by Tesla. It then describes various techniques for wireless power transfer, dividing them into non-radiative (inductive coupling, capacitive coupling, magnetodynamic coupling) and radiative (microwaves, lasers) methods. Applications are discussed along with recent research advances and challenges. The document concludes that wireless power transfer has strong potential to provide a more sustainable alternative to fossil fuel power plants.

1. Presented by:
Debdatta Naskar
EE 2nd year

2.  INTRODUCTION
 BACKGROUND
 BASIC OF WIRELESS POWER SYSTEM
 CLASSIFICATION OF WIRELESS POWER TECHNIQUE
 NON-RADIATIVE TECHNIQUE
 RADIATIVE TECHNIQUE
 APPLICATIONS
 RECENT RESEARCHES
 DEMERITS
 CONCLUSION

3. Wireless power transfer (WPT) or wireless energy transmission is the
transmission of electrical power from a power source to a consuming device
without using solid wires or conductors.
It is a generic term that refers to a number of different power
transmission technologies that use time-varying electromagnetic fields.
Wireless transmission is useful to power electrical devices in cases where
interconnecting wires are inconvenient, hazardous, or are not possible.

4.  In the year 1891,Nikola Tesla proposed the method of
wireless transmission of electric power. In 1899, he
performed experiments in the field of pulsed wireless
energy transfer. Tesla’s magnifying transmitter, an
early type of Tesla coil that was 16 meters in diameter,
was able to transmit tens of thousands of watts without
wires.
 In 2007, Prof. Marin Soljacic from Massachusetts Institute of Technology
led a five member team of researchers at MIT and experimentally proved
that magnetic coupled resonance can be utilized transfer of electrical energy
without the use of wires.

5. A wireless power transmission system consists of a transmitter connected to a
source of power, which converts the power to a time-varying electromagnetic
field, and one or more "receiver" devices which receive the power and convert
it back to DC or AC electric power which is consumed by an electrical load. In
transmitter, the input power is converted to an oscillating electromagnetic field
by an "antenna” device. The antenna device may be a coil of wire generating
magnetic field, a metal plate generating electric field, an antenna radiating
radio waves, or a laser generating light. A similar antenna or coupling device
in the receiver converts the oscillating fields to an electric current.
Fig: Generic block diagram of wireless power transmission system

6. WIRELESS POWER
TECHNIQUE
NON-RADIATIVE TECHNIQUE RADIATIVE TECHNIQUE
INDUCTIVE COUPLING
CAPACITIVE COUPLING
MAGNETODYNAMIC
COUPLING
MICROWAVES
LASERS

7. INDUCTIVE COUPLING:
In this case, energy transfer takes place due to mutual induction between primary and
secondary coil. The energy transfer device is usually air-cored. Applications include
transformer, wireless charging pad, electric brushes etc.
CAPACITIVE COUPLING:
In capacitive coupling (electrostatic induction) power is transmitted by electric fields
between electrodes such as metal plates. The transmitter and receiver electrodes form a
capacitor, with the intervening space as the dielectric. It is used in LED lamps.
MAGNETODYNAMIC COUPLING:
In this method, power is transmitted between two rotating armatures, one in the
transmitter and one in the receiver, which rotate synchronously, coupled together by a
magnetic field generated by permanent magnets on the armatures. This device has been
proposed as an alternative to inductive power transfer for non-contact charging of
electric vehicles.

8. a) b)
c)
Fig: a) Inductive coupling, b) Capacitive coupling, c) Magnetodynamic coupling

9. MICROWAVES:
Power transmission via radio waves can be made more directional, allowing longer
distance power beaming, with shorter wavelengths of electromagnetic radiation,
typically in the microwave range. A rectenna may be used to convert the microwave
energy back into electricity. Rectenna conversion efficiencies exceeding 95% have been
realized. Power beaming using microwaves has been proposed for the transmission of
energy from orbiting solar power satellites to Earth.
LASERS:
In the case of electromagnetic radiation closer to the visible region of the spectrum
(tens of micrometers to tens of nanometres), power can be transmitted by converting
electricity into a laser beam that is then pointed at a solar cell receiver. This mechanics
is generally known as "power beaming" because the power is beamed at a receiver that
can convert it to usable electrical energy. Applications include photovoltaic cell.

10. a)
b)
Fig: a) Microwave transmission, b) Photovoltaic cell

11. W P T
CONSUMER
ELECTRONICS
Mobiles, laptops,
game controllers
Stationary devices (flat
screen TV’s, wireless
loud speaker)
INDUSTRIAL
FIELD
Implantable medical
devices ( pacemaker,
defibrillator)
Wireless sensors
actuators, robots,
automatic guided vehicles,
cordless tools, smart cards
Harsh environments
(drilling, mining,
underwater )
TRANSPORT:
Automatic wireless
charging for electric
vehicles, in parking
garages and at
remote kiosks
MILITARY
APPLICATIONS:
covert sensors, mobile
robots, aircraft etc.

12. a) b)
Fig: a) Wireless transport system, b) Splashpower mat,
c)Wireless sensor
c)

13. Fig: Wireless mobile charger

14.  Currently in the U.S., Dr Joseph Hawkins and William Brown are experimenting with
ESPAM, or electronically steerable phased array module. Proposed applications of such
systems include power transfer from ground to air or ground to space through the use of
microwaves.
 Russian Professor Vladimir Vanke has made the most significant contribution to solving
the hurdles of WPT. In order for microwaves to be used as electricity, the radiant energy
needs to be converted into DC power. Vanke solved this problem with the invention of the
cyclotron wave converter.
 Being concerned about global warming, Japan has created an energy plan that states
that 30% of the world’s electrical needs will come from space by the year 2040. The
equipment is not being developed but the plan is to have a series of solar powered satellites
that would provide 1 GW of power each to the main power grid.

15. Wireless power transfer is possible, but when trying to sustain a constant power level,
some problems can occur with the efficiency of the transmission. This occurs most
noticeably in the electromagnetic wave system. The problem with radio waves is that
they scatter the energy in different directions through free space propagation. This causes
the efficiency to be much lower than if they could be transmitted directly to the receiving
antennas. If a world-wide electromagnetic wave WPT system was used, then free space
propagation would cause numerous problems. The free space energy would either go
unused or would be received by antennae that the transmission was not intended for. This
would pose the most direct problem to consumers within the WPT grid. Individual
consumers would either not be receiving their required energy, or would be receiving too
much and paying a much high electricity bill. These are some problems that are trying to
be corrected through multiple antennae arrays, but high efficiencies have yet to be
accomplished. Researchers of wireless power are trying to invent a chip that can be placed
into existing electronics to convert them to wireless. This is still an ongoing process and
has not yet been completed.

16. Wireless power transfer has the potential to change this planet on so
many different levels. With global warming having significant impact
on this earth by 2050, alternatives to high polluting fossil fuel plants
need to be created. Currently wireless power transfer is the most
marketable and sustainable alternative to fossil fuel power plants. With
advancements in the field happening all the time, a worldwide wireless
power transfer system is a possibility in the near future.