• Wireless Power
Transfer (WPT), Wireless Power
Transmission, Wireless Energy
or Electromagnetic Power Transfer
is the transmission of electrical
energy without wires as a physical
4. Why we
need it ?
• One of the major issues in power
system is the losses occurring
during the transmission and
distribution of electrical power.
• The percentage of loss of power
during transmission and
distribution is approximated as
26% around the world.
• The main reason for power loss
during transmission and
distribution is the resistance of
wires used in grid.
5. • According to the World Resources
Institute (WRI), India’s electricity grid
has the highest transmission and
distribution losses in the world – a
• According to a report, published by the
Northeast Group, the Indian
power sector loses around $16.2 billion
to theft every year.
• According to the World Bank
theft reduces India's GDP by around
• Wireless transmission is useful in cases
where interconnecting wires are
inconvenient, hazardous or
impossible to manage.
• Sir NICOLA TESLA was the first one to propose
and research the idea of wireless transmission in
1890, since than many scholars and scientists
have been working to make his dream a reality.
• Experiment in resonant inductive transfer by
Tesla at Colorado Springs 1899. The coil is in
resonance with Tesla's magnifying transmitter
nearby, powering the light bulb at bottom.
7. In 1901, at Shoreham, New York he attempted
to construct a large high-voltage wireless power
station, now called Wardenclyffe Tower , but by
1904 investment dried up and the facility was
Tesla's unsuccessful Wardenclyffe
8. How it will
be done ?
⇢ In a wireless power transmission system, a
transmitter device, driven by electric power
from a power source, generates a time-
varying electromagnetic field, which
transmits power across space to a receiver
device, which extracts power from the field
and supplies it to an electric load.
Different methods of transmission proposed
by different scientist and scholars are:
1. Atmospheric conduction method of
2. Electrodynamic induction method:
• Microwave method
• Laser method
• In 1899, Sir NICOLA TESLA and HEINRICH HERTZ
powered a fluorescent lamp keeping it 25 miles
away from source without using wire. Wireless
power transmission experiments at WARDEN
CLYFFE High frequency current, of a Tesla coil,
could light lamps filled with gas (like neon). In
this method a closed circuit is made using
transmitter, ionized path between upper
atmosphere and transmitter, second ionized
path connecting receiver. The circuit back to the
transmitter is completed through the earth.
• High potential is maintained at transmitter and
receiver end. A high potential transmitter
transmits an “electric impulse” through the
ionized path to the upper atmosphere where it
ionizes the air, and this air between the
transmitter and receiver would conduct like a
neon tube .
• In the case of electromagnetic
radiation closer to visible region of
spectrum (10s of microns (um) to 10s
of nm),power can be transmitted by
converting electricity into a laser
beam that is then pointed at a solar
• This mechanism is generally known as
"power beaming" because the power
is beamed at a receiver that can
convert it to usable electrical energy.
• At the receiver, special photovoltaic
laser power converters which are
optimized for monochromatic light
conversion are applied.
15. Disadvantages of
⇢ Laser radiation is hazardous. Without
a proper safety mechanism, low
power levels can blind humans and
other animals. High power levels can
kill through localized spot heating.
⇢ Conversion between electricity and
light is limited. Photovoltaic cells
achieve 40%–50% efficiency.
⇢ Requires a direct line of sight with the
16. Micro Wave
• 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
• The principle of Evanescent principle of
Electromagnetic Wave Coupling extends
• In this, power is transferred between coils
of wire by a magnetic field. The transmitter
and receiver coils together form
a transformer. An alternating current (AC)
through the transmitter coil (L1) creates an
oscillating magnetic field (B) by Ampere's
• The magnetic field passes through the
receiving coil (L2), where it induces an
alternating EMF (voltage) by Faraday's Law,
which creates an alternating current in the
• The induced alternating current may either
drive the load directly, or be rectified
to direct current (DC) by a rectifier in the
receiver, which drives the load.
19. Real Life
Modern inductive power transfer, an
electric toothbrush charger. A coil in the
stand produces a magnetic field, inducing
an alternating current in a coil in the
toothbrush, which is rectified to charge
• In this, energy 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
• An alternating voltage generated by the
transmitter is applied to the transmitting plate,
and the oscillating electric field induces an
alternating potential on the receiver plate
by electrostatic induction, which causes an
alternating current to flow in the load circuit.
• The amount of power transferred increases
with the frequency, the square of the voltage,
and the capacitance between the plates, which
is proportional to the area of the smaller plate
and (for short distances) inversely proportional
to the separation
• In this, there are two transmitter plates and two
receiver plates. Each transmitter plate is coupled to a
receiver plate. The transmitter oscillator drives the
transmitter plates in opposite phase (180° phase
difference) by a high alternating voltage, and the load
is connected between the two receiver plates.
• The alternating electric fields induce opposite phase
alternating potentials in the receiver plates, and this
"push-pull" action causes current to flow back and
forth between the plates through the load.
24. Applications :
ICM Electric tooth
CCM Charging portable
routing in large-
circuits, Smart cards
25. Applications :
MWM Solar Power
drone aircraft and
Laser Charging portable
drone aircraft and
• Need for grids, substations etc are
•Low maintenance cost
•More effective when the transmitting and
receiving points are along a line-of-sight
• Can reach the places which are remote
27. Disadvantages :
• When microwaves are used, interference may
• When LASERS are used, conversion is inefficient
due to absorption losses.
• It is radioactive in nature
• Distance constraint , initial cost is high.
• Field strength has to be under safety levels
• High frequency signals should be supplied for
air ionization which is not feasible.
28. Conclusion :
• Transmission without wires- a reality
• Low maintenance cost. But, high initial
• Better than conventional wired transfer
• Energy crisis can be decreased
• Low loss
• In near future, world will be completely