22-11-2012, 05:58 PM
Wireless Power Transmission – A Next Generation Power Transmission System
1Wireless Power Transmission.pdf (Size: 195.07 KB / Downloads: 63)
ABSTRACT
In this paper, we present the concept of transmitting power without
using wires i.e., transmitting power as microwaves from one place
to another is in order to reduce the transmission and distribution
losses. This concept is known as Microwave Power transmission
(MPT). We also discussed the technological developments in
Wireless Power Transmission (WPT). The advantages,
disadvantages, biological impacts and applications of WPT are
also presented.
INTRODUCTION
One of the major issue in power system is the losses occurs during
the transmission and distribution of electrical power. As the
demand increases day by day, the power generation increases and
the power loss is also increased. The major amount of power loss
occurs during transmission and distribution. The percentage of loss
of power during transmission and distribution is approximated as
26%. The main reason for power loss during transmission and
distribution is the resistance of wires used for grid. The efficiency
of power transmission can be improved to certain level by using
high strength composite over head conductors and underground
cables that use high temperature super conductor. But, the
transmission is still inefficient. According to the World Resources
Institute (WRI), India’s electricity grid has the highest
transmission and distribution losses in the world – a whopping
27%. Numbers published by various Indian government agencies
put that number at 30%, 40% and greater than 40%. This is
attributed to technical losses (grid’s inefficiencies) and theft [1].
WIRELESS POWER TRANSMISSION
Nikola Tesla he is who invented radio and shown us he is indeed
the “Father of Wireless”. Nikola Tesla is the one who first
conceived
the idea Wireless Power Transmission and demonstrated “the
transmission of electrical energy without wires" that depends upon
electrical conductivity as early as 1891[2]. In 1893, Tesla
demonstrated the illumination of vacuum bulbs without using
wires for power transmission at the World Columbian Exposition
in Chicago. The Wardenclyffe tower shown in Figure 1 was
designed and constructed by Tesla mainly for wireless
transmission of electrical power rather than telegraphy [3].
Wireless Power Transmission System
William C. Brown, the pioneer in wireless power transmission
technology, has designed, developed a unit and demonstrated to
show how power can be transferred through free space by
microwaves. The concept of Wireless Power Transmission System
is explained with functional block diagram shown in Figure 2. In
the transmission side, the microwave power source generates
microwave power and the output power is controlled by electronic
control circuits. The wave guide ferrite circulator which protects
the microwave source from reflected power is connected with the
microwave power source through the Coax – Waveguide Adaptor.
The tuner matches the impedance between the transmitting antenna
and the microwave source. The attenuated signals will be then
separated based on the direction of signal propagation by
Directional Coupler. The transmitting antenna radiates the power
uniformly through free space to the rectenna
ADVANTAGES, DISADVANTAGES,
AND BIOLOGICAL IMPACTS OF WPT
Advantages
Wireless Power Transmission system would completely eliminates
the existing high-tension power transmission line cables, towers
and sub stations between the generating station and consumers and
facilitates the interconnection of electrical generation plants on a
global scale. It has more freedom of choice of both receiver and
transmitters. Even mobile transmitters and receivers can be chosen
for the WPT system. The cost of transmission and distribution
become less and the cost of electrical energy for the consumer also
would be reduced. The power could be transmitted to the places
where the wired transmission is not possible. Loss of transmission
is negligible level in the Wireless Power Transmission; therefore,
the efficiency of this method is very much higher than the wired
transmission. Power is available at the rectenna as long as the WPT
is operating. The power failure due to short circuit and fault on
cables would never exist in the transmission and power theft would
be not possible at all.
APPLICATIONS OF WPT
Generating power by placing satellites with giant solar arrays in
Geosynchronous Earth Orbit and transmitting the power as
microwaves to the earth known as Solar Power Satellites (SPS) is
the largest application of WPT. Another application of WPT is
moving targets such as fuel free airplanes, fuel free electric
vehicles, moving robots and fuel free rockets. The other
applications of WPT are Ubiquitous Power Source (or) Wireless
Power Source, Wireless sensors and RF Power Adaptive
Rectifying Circuits (PARC).
CONCLUSION
The concept of Microwave Power transmission (MPT) and
Wireless Power Transmission system is presented. The
technological developments in Wireless Power Transmission
(WPT), the advantages, disadvantages, biological impacts and
applications of WPT are also discussed.
This concept offers greater possibilities for transmitting power
with negligible losses and ease of transmission than any invention
or discovery heretofore made. Dr. Neville of NASA states “You
don’t need cables, pipes, or copper wires to receive power. We can
send it to you like a cell phone call – where you want it, when you
want it, in real time”. We can expect with certitude that in next few
years’ wonders will be wrought by its applications if all the
conditions are favourable.