Wireless Elecricity Essays

Wireless Elecricity Essays Wireless Elecricity Essay Wireless Elecricity Essay Niharika Sharma Applied Electronics and Instrumentation Engineering, [emailprotected] com Varun Pachauri Electronics and Communication Engineering, [emailprotected] com Wireless Electricity Abstract- The present paper intends to link several disciplines in an attempt to describe the concept of wireless electricity. Wireless transmission is useful in cases where interconnecting wires are inconvenient, unaffordable, expensive, hazardous, unwanted or impossible. A large part of the energy sent out by the generating plant must arrive at the receiver to make the system economical.Some common forms of wireless electricity transmission methods are Direct Induction followed by resonant magnetic induction, electromagnetic radiation  in the form of  microwaves  or  lasers. With this technology we can reduce power losses produced through wired lines. Different concepts and application of wireless power transmission are discussed in this paper. Introduction The definition of Wireless Pow er Transmission is: efficient transmission of electric power from one place to another through vacuum or an atmosphere without the use of wire or any other substance.Maxwells theory of electromagnetism, published in 1865 mentions electromagnetic waves moving at the speed of light, and the conclusion that light itself was just a wave. In 1886 H. Hertz performed an experiment with pulsed wireless energy transfer. . He produced an apparatus that generated and detected microwaves in the UHF region. Tesla also performed experiments in the field of pulsed wireless energy transfer in 1899. Teslas Magnifying Transmitter, an early type of Tesla Coil that measured 16 meters in diameter, could able to transmit tens of thousands of watts without wires.In present electricity generation system we waste more than half of its resources. The transmission of power without wires may be one idle alternative for electricity. Future suitable and largest application of the WPT via microwave is a Space Sol ar Power Satellite. History of Wireless Electricity In 1864, James Maxwell predicted the existence of radio waves by means of mathematical model. In 1884, John Poynting realized that the Poynting Vector would play an important role in quantifying the electromagnetic energy.In 1888, bolstered by Maxwells theory, Heinrich Hertz first succeeded in showing experimental prove of radio waves by his spark-gap radio transmitter. The prediction and prove of the radio wave in the end of 19th century was start of the wireless power. The Raytheon Company performed the first successful WPT experiment in 1963. In this experiment power was transmitted with a DC-to-DC efficiency of 13%. The Raytheon Company also demonstrated a microwave-powered helicopter in 1964. In 1975, Jet propulsion lab of NASA carried out an experiment and demonstrated the transfer of 30 kW over a distance of 1 mile.This test demonstrated the possibilities of wireless energy outside the laboratory. Rockwell International and David Sarnoff Laboratory operated in 1991 a microwave powered rover at 5. 87 GHz. Three kilowatts of energy was transmitted and 500 watts was received. In 1980s, Japanese scientists developed the MPT technologies and research. In 1983 and 1993, Matsumoto’s team carried out the first Microwave Power Transmission experiment in space. The rocket experiment was called Microwave Ionosphere Nonlinear Interaction experiment i. . MINIX in 1983 (Fig. 1) and International Space Year – Microwave Energy Transmission in Space in 1993, respectively. They focused nonlinear interaction in between intense microwave and plasmas. In this experiment, they used cooker-type 800W-2. 47GHz magnetron for microwave transmitter. New wave-wave-particle interaction phenomenon was observed in this experiment. Plasma theory and computer experiments also supported the observations. Figure 1. MINIX Rocket experiment in 1983 Technologies for Wireless ElectricityThe modern ideas are dominated by microwa ve power transmission called Solar power satellite to be built in high earth orbit to collect sunlight and convert that power into microwaves, then beamed to a very large antenna on earth, the microwaves would be converted into conventional electrical energy. A microwave transmission system consists of three essential parts: ? Electrical energy to microwave energy conversion ? Absorption antenna that collects the waves ? (Re)conversion to electrical energy Figure 2. Microwave transmitter and rectennaThe microwave source consists of a microwave oven magnetron with electronics to control the output energy. The output microwave energy ranges from 50 W to 200 W at 2. 45 GHz. A coaxial cable connects the output of the microwave source to coax-to-waveguide adapter. This adapter is connected to a waveguide ferrite circulator which protects the microwave source from reflected energy. The circulator is connected to a tuning waveguide to match the waveguide impedance to the antenna input impe dance. The slotted waveguide antenna consists of 8 wave guide sections with 8 slots per section.These 64 slots radiate the energy uniformly through free space to the rectenna. The slotted waveguide antenna is ideal for energy of its high aperture efficiency (;gt;95%) and high power handling capability. A rectifying antenna called a rectenna receives the transmitted energy and converts the microwave power to direct current (DC) power. This rectenna consists of 6 rows of dipoles antennas where 8 dipoles belong to each row. Every row is connected to a rectifying circuit which consists of low pass filters and a rectifier. The rectifier is a Ga As Schottky barrier diode i. . impedance matched to the dipoles by a low pass filter. The 6 rectifying diodes are connected to light bulbs for indicating that the energy is received. The light bulbs also dissipated the received energy. This rectenna has a 25% collection and conversion efficiency, but rectennas have been tested with more than 90% e fficiency at 2. 45 GHz. Another possibility is to use highly efficient fibre lasers for wireless energy transmission where the possibilities are similar to microwaves concept but lasers emit energy at frequencies much higher than microwave.For several years NASA, ENTECH, and UAH have been working on various aspects of collection of the laser radiation and conversion to electrical energy for laser wireless energy transmission. Figure 3. Two optical forms of wireless antenna formed of search light beam-ionised atmospheric stream Applications of Wireless Electricity Wireless Power for Space Solar Satellites * The largest application for microwave power transmission is Space Solar Power satellites. In this application, solar energy is captured in space and converted into electricity.The electricity is converted into microwaves and transmitted to the earth. The microwave energy will be captured with antennas and converted into electricity. NASA is still investigating the possibilities of solar power satellites. Main problem is the high investment cost due to the space transport. The current rates on the Space Shuttle run between $7,000 and $11,000 per kg of transported material. * Table. 1-Parameters for transmiting antenna for sps system * Figure. 4. Space Solar Power Satellite Power Supply for Rural AreasWireless power can be an option for power supply to rural areas. In 1993, a project presented about wireless power supply in Alaska. Because of limited infrastructure, numbers of small rural communities in Alaska must provide their own electricity. These systems can be expensive or just not available. At the moment, the small communities produce their own power with mostly diesel engines. These produce so noise and pollution. Also the required fuel has to be transported over long distances. This results in an electricity price in excess of $40/kWh.In Alaska cable connections through water is no alternative because of ice. With the help of WPT, the required power production of the communities can be combined. It can reduce noise, pollution and transportation of fuel. WPT may be capable of transmitting electrical power to Alaska’s remote villages. To investigate these possibilities, a project was conducted named Alaska21†. System used for the project consisted of a 2. 46 GHz phased array design. The distances should be bridged are between 1 and 15 miles. Figure. 5. Alaska’21 * V.Merits of Wireless Electricity An electrical distribution system, based on this method would eliminate the need for the costly and capital intensive grid of cables, towers, and substations. The system would also reduce the cost of electrical energy used by the consumer and rid the landscape of wires, cables, and transmission towers. There are areas of the world where the need for electrical energy exists, yet there is no method for delivering energy. Africa is in need of energy to run pumps to tap into the vast resources of water under the Sahara D esert.Rural areas, such as those in China, require the electrical energy necessary to bring them into the 20th century and to equal standing with western nations. The wireless transmission will solve most of above problems. The electrical power can be economically transmitted without wires to any terrestrial distance, so there will be no transmission and distribution loss. Figure 6. An office using wireless electricity Demerits of Wireless Electricity A common criticism of the wireless power system is regarding its possible biological effects.Calculating the circulating reactive power, it was found that the frequency is small and such a frequency is very biologically compatible. A general perception that microwaves are harmful has been a major obstacle for the acceptance of power transmission with microwaves. One major concern is that the long-term exposure to low levels of microwaves might be unsafe and even could cause cancer. Conclusion The transmission of energy without wires is not a theory or a mere possibility, it is now a reality. The electrical power can be economically transmitted without wires to any terrestrial distance.Many researchers have established in numerous observations and experiments qualitative and quantitative. It is clear that wireless power transmission systems in the range of 100 W to 100 kW to cannot compete with traditional systems just looking at the costs. At those places where economic competition is not the prime consideration, it can be an option. Microwave wireless energy transmission can supply energy to those places that are difficult to reach. Especially small communities in rural areas could be supplied with power using wireless power transmission.The problems of a possible lack of energy during the next fifty or hundred years could be solved by the Space Solar Power Station. The system would reduce the cost of electrical power used by the consumer and get rid of the landscape of wires, cables, and transmission towers. It has negligible drawbacks like reactive power which was found insignificant and biologically compatible. References James O. McSpadden, â€Å" Wireless Power Transmission Demonstration†, Texas Aamp;M University, June, 1997. Elvina Finzi, Carlo Lombardi, and Leopold Summerer. A lunar IPWR: A pre-feasibility study. In IAC 2006, volume IAC-06- D2. 8. , Valencia, Spain, Oct. 2006. IAF. Thomas W. Benson, â€Å"Wireless transmission of power now possible†, News Letter, pp1118 – 9, March, 1920. Charych Arthur (Setauket, NY), â€Å"System and method for wireless electrical power transmission†, Patent No. 6,798,716, September 28, 2004. Joe T. Howell, et. al, â€Å"Advanced receiver / converter experiments for laser wireless power transmission†5th. Wireless transmission conference, pp 1-8, Garanda, Spain, 2004. Nikola Tesla, â€Å"The true wireless†, Electrical Experiment, May, 1919. 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