International Journal of Research In Science & Engineering
Volume: 1 Issue:3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
STUDY AND OVERVIEW OF WIRELESS TRANSMISSION OF
ELECTRICAL POWER
Swapnil R. Thakare 1 , Atul N. Shire 2 Umesh S. Jawarkar3
1
Student, Electronics & Tele. Engineering, J.D.I.E.T. Yavatmal, [email protected]
Ass. Prof., Electronics & Tele. Engineering, J.D.I.E.T. Yavatmal, [email protected]
3
Ass. Prof., Electronics & Tele. Engineering, J.D.I.E.T. Yavatmal, [email protected]
2
ABSTACT
The objective of this research work is to give a overview of latest researches and development in the field
of wireless transmission of electrical power. There are many technology for wireless power transmission like
Induction, Electromagnetic transmission, Evanescent wave coupling, Electrodynamics induction, Radio and
microwave and Electrostatic Induction are illustrate. Also discus on difference between various methods and
their related application in wireless electrical power system. This study also focuses on latest technologies,
advantages and disadvantages in this field.
Electricity is important in today’s modern life. Without electricity it is hard to imagine passing a day.
The conventional use of electricity is made possible through use of wires. However researchers in MIT have
devised a means of providing electricity without wires. Wireless Electricity, a portmanteau for wireless electricity,
is term coined initially and used. This principle of wireless electricity works on principle of using coupled
resonant objects for the transmission of electricity. In this paper, we have presented the concept of wireless
transmission i.e. power without the usage of any type of the electrical conductor or wires. We present an idea
discussed here, how energy can be transmitted as microwaves, so as to reduce the transmission and allocation
losses, known as Microwave Power transmission (MPT). We have also cited several aspects relating to history of
wireless power transmission systems along with the present day scenario of Power transmission systems and also
some of the developmental changes in Wireless Power Transmission (WPT). The Basic Design and
Implementation of Wireless power System has also been give.
Key words : wireless transmission, WiTricity, solar power
1. INTRODUCTION
In the ancient time, designers and engineers have faced challenges involving power: the continuity of
supplied power, recharging batteries, optimizing the location of sensors, and dealing with rotating or moving joints.
Although those challenges rest as it is, new demands that arise from increased use of mobile phones devices and
operation in dirty or wet environments mean that designers require new approaches to supplying power to
equipment.
Wireless Transmission of power from the time of Tesla has been an underdeveloped technology. Tesla had
always works to introduce worldwide wireless energy distribution system. But because of lack of funding and
technology of that time, he was not able to complete the job. Then from that time this technology has not been
developed up to level which would be completely applicable for practical reason. Scientist has always been going on
and latest developments have been observed in this field. Adopt advances wireless power transmission has not been
adopted for commercial use.
1.1 Method of wireless electrical power transmission system
"Wireless power transmission" is a term that refers to a number of different technologies for transmitting
power by means of time-varying electromagnetic fields. The technologies, listed below, differ in the distance over
which they can transmit power efficiently, whether the transmitter must be focus (directed) at the receiver.
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International Journal of Research In Science & Engineering
Volume: 1 Issue:3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
1.1.1 Inductive coupling and Resonant inductive coupling
The electrodynamics induction wireless transmission of power technology to induce a current relies on the
use of a magnetic field generated by an electric current in a second conductor. This effect occurs in the
electromagnetic near field, with the secondary coil near to the primary. As the distance between the primary coil and
secondary coil is increased, more of the primary's magnetic field misses the secondary coil. Even over a relatively
short range the inductive coupling is grossly inefficient, wasting mu ch of the transmitted energy.[8] The primary
coil and secondary coil of a transformer are not directly connected to each other, Energy transfer takes place through
a process called as mutual induction.
1.1.2 Capacitive coupling
In capacitive coupling , the dual of inductive coupling, energy is transmitted between electrodes such as
metal plates by electric fields. the capacitor form by transmitter and receiver electrodes, with the intervening space
as the dielectric.[10] An alternating voltage create by the transmitter is given to the transmitting plate, and
by electrostatic induction the oscillating electric field induces an alternating potential on the receiver
plate,[10] which tern into alternating current flow in the load circuit. Capacitive coupling used in low power
application, because the very high voltages on electrodes required transmitting significant power can be hazardous.
1.1.3 Magneto dynamic coupling
In this method, electric energy is transmitted between two rotating armatures, i.e. transmitter and receiver,
which rotates synchronously, coupled each other by a magnetic field generated by permanent magnets on the
armatures. The transmitter armature is turned either by or as the rotor of an electric motor, and its magnetic field
apply torque on receiver armature, turning it. The magnetic field acts like a mechanical coupling between the
armatures. The receiver armature creates power to drive the load, either by turning an electric generator or by using
the receiver armature as the rotor in an induction generator .
1.1.4 Far-field or radioactive techniques
This method used for longer range, often multiple kilometre ranges, where the distance is much greater
than the diameter of the device(s). The main reason for longer ranges with radio wave and optical devices is the fact
that electromagnetic radiation in the far-field can be made to match the shape of the receiving area (using
high directivity antennas or well-collimated laser beams). The Antennas maximum directivity for is physically
limited by diffraction.
In simply, visible light (from lasers) and microwaves are the forms of electromagnetic radiation best suited
to power transfer. The Rayleigh criterion state that any radio wave, microwave or laser beam will spread and
become weaker and diffuse over distance; transmitter antenna are larger or laser aperture compared to the
wavelength of radiation, the tighter the beam and the less it will spread as a function of distance (and vice versa).
Power transmission via radio waves can be made more reliable, it allow longer distance power beaming,
with shorter wavelengths of electromagnetic radiation, typically in the microwave range.[11] A rectenna can be used
to convert the microwave energy back into electrical energy. Rectenna conversion efficiencies increase up to 95%
have been realized. Power beaming us ing microwaves has been used for the transmission of electrical power from
orbiting solar power satellites to Earth station.
Below table gives the difference between various methods of wireless power system.
Method
Inductive coupling
Range
Directivity
Frequency
Antenna devices
Current and or possible future
applications
Short
Low
Hz - MHz
Wire coils
Electric tooth brush and razor
battery charging, induction stove
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Resonant inductive
coupling
Mid-
Low
MHz GHz
Capacitive coupling
Short
Low
kHz - MHz
Magneto dynamic
Microwaves
Short
Long
N.A.
High
Hz
GHz
Light waves
Long
High
≥THz
Tuned wire coils,
lumped element
resonators
Electrodes
Rotating magnets
Parabolic
dishes, phased
arrays, rectennas
Lasers,
photocells,
lenses,
telescopes
e-ISSN: 2394-8299
p-ISSN: 2394-8280
Charging portable devices
( WiTricity), biomedical implants,
electric vehicles,
Charging portable devices, power
routing in large scale integrated
circuits, Smartcards.
Charging electric vehicles.
Solar power satellite, powering
drone aircraft.
Powering drone aircraft, powering
space elevator climbers.
Table-1: Various methods and their comparison
2. LITERATURE SURVEY
In year 1826 Andre-Marie Ampere design Ampere's circuital law and said that electric current produces a
magnetic field. in 1831 Michael Faraday said that in Faraday's law of induction , describing by means of a timevarying magnetic flux the electromagnetic force induced in a conductor. James Clerk Maxwell, in 1862 synthesized
these and other equations, observations, and experiments of electricity, magnetism and optics into a consistent
theory, deriving Maxwell's equations. Maxwell illustrate the existence of electromagnetic waves Treatise on
Electricity and Magnetism.[1] In 1884 John Henry Poynting design equations for the transfer of power in
electromagnetic field, Poynting's theorem and vector, which are used for analysis of wireless electricity energy
transfer systems.[11] In 1888 Heinrich Rudolf Hertz shows that radio waves, confirming the prediction of
electromagnetic waves by Maxwell.[1]
In first experiments inventor Nikola Tesla performed the in wireless power transmission at the turn of the
20th century.[3] In the period 1891 to 1904 tesla experimented with spark-excited radio frequency resonant
Fig-1: Tesla’s experimental lamp
Fig-2: Warden clyffe Tower, including partially-complete cupola
Transformer, this coil called as Tesla coils, which produce high AC voltages on capacitive terminal.[2] With these
experiment he could transmit power for short distances wirelessly. At Colorado Springs laboratory during 18991900, by using voltages 20 megavolts created by coil, they was light up three incandescent lamps by resonant
IJRISE| www.ijrise.org|[email protected] [15-20]
International Journal of Research In Science & Engineering
Volume: 1 Issue:3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
inductive coupling at a distance of about 100 feet.[5][6] The resonant inductive coupling which Tesla invent is now
a familiar technique used in electronics. As mentioned above it is a "near-field" effect.[2] so it is not able to supply
power over long distances. The development of microwave technique using klystron tube and magnetron tubes
and parabolic antennas made radioactive (far-field) methods practical for the first time, and the first time longdistance wireless energy transmission was achieved in the 1960s by William C. Brown.[11] A major development in
microwave research in the 1970s and 80s was to develop a solar power satellite.[12] In 1968, Peter Glaser, this
would harvest power from sunlight using solar cells and beam it send to the Earth as microwaves light beam to huge
rectennas, which convert microwave back into electrical energy on the electric power grid panel.[11] In landmark
1975 high power experiments, Brown demonstrated short range transmission of 475 W of microwaves at 54% DC to
DC efficiency, and Brown and Robert Dickinson at NASA's Jet Propulsion Laboratory transfer 30 kW DC output
power across 1.5 km with 2.38 GHz microwaves from a 26 m dish to a 7.3 x 3.5 m rectenna array.[11] The incidentRF to DC conversion of the rectenna was gives 80% efficiency.[11] In 1983 Japan launched MINIX (Microwave
Ionosphere Nonlinear Interaction Experiment), a rocket to test transmission of high power microwaves through the
ionosphere.
2.1 Current technology in wireless power transmission
2.1.1 By Using Microwave Power Transmission in Solar Power Satellites (SPS)
Solar power generating satellites launched into space which transmits power to Earth stations. In the year
1968 this technique was first proposed and all experiments have only been carried out in terrestrial lab. In high earth
orbit the SPS satellites would be kept at geosynchronous location. This technique can allow receive light 99% of the
year. For collecting the incoming microwaves a large rectenna array facility will be built on the Earth. The satellite
will need to be built with a retro directive transmitter which locks on to a pilot beam emanated from the ground
station. Due to some spectrum regulatory issues most of the research is done in the 2.4 GHz to 5.8 GHz range.[10]
Japanese government agency is planning to send up 10 to 100 kW low earth orbit satellite to prove its feasibility. [2]
Fig-3: Solar power satellite
2.1.2 Microwave Transmitter
The most current research and proposals done for microwaves as the frequency range of choice for
transmission. In present day near about 76% efficiency is possible using current technology for microwave energy
transmission. For maximum efficiency the waves must be focused on rectenna so that full energy transmitted by the
source is incident on wave collection device. The most commonly used transmitters for microwaves are the
travelling wave tube (TWT), magnetron and klystron. The klystron converts DC current to microwave, however it is
also somewhat expensive.
Many researchers are looking to use magnetrons instead of klystron because they are less expensive and
efficient. Magnetron frequency output is not controllable as klystron or TWT but power transmission is more lenient
to frequency fluctuations than communication systems. One of the more common proposals would be for an array of
magnetrons to be used as the transmitter. One of the main advantages to using many smaller magnetrons as opposed
to a few klystrons is that 300 W to 1kW magnetrons are already mass produced for microwave ovens.[7]
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International Journal of Research In Science & Engineering
Volume: 1 Issue:3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
Fig-4: Microwave transmitter
2.2 Latest innovation and experiment
Fig-5: WiT ricity image of how the fields work
Fig-6: .Experiment at MIT for WPT
A child on swing is a good example of technique. A swing is one of type of mechanical resonance, so only
when the child pumps his legs at the natural frequency of the swing is he able to impart substantial energy. The
developed design carried out two copper coils, each a self resonant system. One coil attached to the power source,
which is sending unit. Electromagnetic waves do not effect on environment, it spread over the space with a nonradioactive magnetic field oscillating at MHz frequencies. The non-radioactive field transfer energy to the other coil
(means receiving unit), which is specially developed for resonate with field.
3. FUTURE SCOPE
3.1 Power-Generating Solar Satellite
Fig-7: Japan’s wireless, power-generating, solar satellite
One possible application can be a solar power satellite as shown in Figure 7. This idea consists of having a
satellite with solar panels in orbit. The satellite creates electrical power using solar cells. This energy will be
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International Journal of Research In Science & Engineering
Volume: 1 Issue:3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
converted into an electromagnetic wave which then transmitted wirelessly means in the form of strong light beam to
receivers on the earth. The receivers then convert the transmitted electromagnetic wave energy back into usable
electrical energy. Additionally, 80% conversion efficiency is desired within both the transmitter and the receiver
unit.. Thus, the development of solar power satellites could consistently provide cle an energy around the world.
4. CONCLUSION
Wireless electrical energy transmission of electrical power can be large scope in electrical and electronics
engineering for future scope for power generation and transfer wirelessly. Solar power satellites are the future of
supplying non conventional energy. The various methods and aspects related with wireless transmission of electrical
energy are discussed. The evolution of the technique from the time of Tesla has been overviewed.
ACKNOWLEDGEMENT
The authors would like to thank Ass. Prof. A. N. Shire and Ass. Prof. U. S. Jawarkar , Department of
Electronics and Telecommunication Engineering, Jawaharlal Darda Institute of Engineering And Technology,
Yavatmal, for his continuous help and suggestions to improve the eminence of this paper.
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