14-07-2011, 03:35 PM
[attachment=14448]
CHAPTER 1
INTRODUCTION
In this era of modernization, electricity has become the cup of life. A moment without electricity makes your thinking go dry. The major source of conventional form of electricity is through wires. The continuous research and development has brought forward a major breakthrough, which provides electricity without the medium of wires. This wonder baby is called WiTricity.
There are certain small but very useful discoveries made in history, which changed the world for ever, Newton’s gravitational law, Watt’s steam engine, Thomson’s bulb and many more. But a renaissance occurred with the invention of Electromagnetic Waves by Maxwell. Sir Jagdish Chandra Bose successfully generated electromagnetic waves having wavelength in the range of 5mm to 25 mm. Thereafter an Italian scientist named Marconi succeeded in transmitting electromagnetic waves up to a distance of several miles.
And with this there started a new era called WIRELESS TECHNOLOGY. Today, as we can see the word ‘wireless’ is common in day – to – day life. Wireless communication has made the world smaller. Almost each and everything is wireless or cordless. Cordless mouse, cordless keyboard, satellite communication, mobiles, cordless microphones and headphones, wireless internet service i.e. WIFI, etc. And these have definitely increased the standard of living.
In fact it dates back to the 19th century, when Nikola Tesla used conduction based systems instead of resonance magnetic fields to transfer wireless power. As it is in Radiative mode, most of the Power was wasted and has less efficiency. Further, in 2005, Dave Gerding coined the term WiTricity which is being used by the MIT researchers today.
Moreover, we all are aware of the use of electromagnetic radiation (radio waves) which is quite well known for wireless transfer of information. In addition, lasers have also been used to transmit energy without wires. However, radio waves are not feasible for power transmissions because the nature of the radiation is such that it spreads across the place, resulting into a large amount of radiations being wasted. And in the case of lasers, apart from requirement of uninterrupted line of sight (obstacles hinder the transmission process). It is also very dangerous
WiTricity is nothing but wireless electricity. Transmission of electrical energy from one object to another without the use of wires is called as WiTricity. WiTricity will ensure that the cell phones, laptops, iPods and other power hungry devices get charged on their own, eliminating the need of plugging them in. Even better, because of WiTricity some of the devices won't require batteries to operate.
Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all those devices typically rely on chemical energy storage(Battery) As they are becoming daily needs to present generation, Wire less energy transfer would be useful for many applications as above and they need midrange energy.
CHAPTER 2
LITERATURE REVIEW
In 2006 MIT researchers discovered a new method to provide electricity to remote objects without wires. Wiricity is based on coupled resonant objects. In 2007 researchers implemented a prototype using self resonant coils. In this first experiment they demonstrated efficient non-radiative power transfer over distance up to eight times the radius of the coils. This experiment was done using two copper coils. Each coil act as self resonant system. One of the coils is attached to the electricity source. Instead of irradiating the environment with electromagnetic waves, it fills the space with a non-radiative magnetic field oscillating at MHz frequencies. The non-radiative field mediates the power exchange with the other coil, which is specially designed to resonate with the field. The resonant nature ensures strong interaction between sending unit and receiving unit.
In the first experiment they successfully demonstrated the ability to power a 60W light bulb from a power source that was 2 meters away with 40% efficiency approximately. They used two capacitively loaded copper coils of 51 cm in diameter designed to resonate in the MHz range. One coil was connected to a power source, the other to a bulb. In this experiment the coils were designed to resonate at 10MHz. The setup powered the bulb oh even when the coils were not in line of sight. The bulb glowed even when wood, metal, and other devices were placed in between the coils.
Some disadvantages invoved in this technique is Wireless power transmission can be only in few meters, efficiency is about 40% only, As witricity is in development stage, lot of work is done for improving the efficiency and distance between transmitter and receiver.
Witricity has a bright future in providing wireless electricity. There are no limitations in witiricity power applications. Some of the potential applications are pwering of cell phones, laptops and other devices that normally run with the help of batteries or plugging in wires. Witricity applications are expected to work on the gadgets that are in close proximity to a source of wireless 'power, where in the gadgets charges automatically without necessarily, having to get plugged in. By the use of witricity there is no need of batteries or remembering to recharge batteries periodically. If a source is placed in each room to provide power supply to the
Wholehouse
Witricity has many medical applications. It is used for providing electric power in many commercially available medical implantable devices.
Another application of this technology includes transmission of information. It would not interfere with radio waves and it is cheap and efficient.
Wireless electricity (in short, witricity) is a recently developed technology for wireless power transfer . It has been demonstrated that it is feasible to transmit a significant amount of power at a high efficiency that has never been achieved previously. Despite this significant development, its effective transmission distance is limited by the size of the resonator. Relayed witricity power transfer system consists of at least three resonators (source, relay(s) and device) with the same resonant frequency, a driving loop, and an output loop. The source resonator is coupled inductively with the driving loop linked to an RF power source. Similarly, the device resonator is coupled inductively with the output loop to supply power to an external load. With the presence of the relay resonator, the device and source can interact more strongly, exchange energy more quickly and deliver power more efficiently when compared with the system without the relay resonator.[1]
CHAPTER 3
HISTORY OF WITRICITY
The idea of wireless generation and transmission of power is in experiment from a long time. The person who first paved the way of dreaming wireless power is NIKOLO TESLA. In 1888 he developed the principles of his Tesla coil and began working with his ideas for polyphase systems, which would allow transmission of AC electricity over large distances. The connection would be made by electrostatic induction or conduction through plasma. Tesla firmly believed that Wardenclyffe tower would permit wireless transmission and reception across large distances with negligible losses. But after lighting vacuum tubes wirelessly, he provided us with enough evidence of the potential and feasibility of wireless power transmission network. In 1902 Nikola Tesla patented a device, he called the device a "high-voltage, air-core, self-regenerative resonant transformer that generates very high voltages at high frequency"; it was a Tesla coil that transferred its energy using resonant transfer from the bottom coil a few feet through air to the top coil. This avoided arcing and permitted very high voltages to be created, and is one of the more common types built today.
Fig 3.1 Nikolo Tesla
In the early 1960s resonant inductive wireless energy transfer was used successfully in implantable medical devices including such devices as pacemakers and artificial hearts. While the early systems used a resonant receiver coil, later systems implemented resonant transmitter coils as well. These medical devices are designed for high efficiency using low power electronics while efficiently accommodating some misalignment and dynamic twisting of the coils. The separation between the coils in implantable applications is commonly less than 20 cm. Today resonant inductive energy transfer is regularly used for providing electric power in many commercially available medical implantable devices
Wireless electric energy transfer for experimentally powering electric automobiles and buses is a higher power application (>10 kW) of resonant inductive energy transfer. High power levels are required for rapid recharging and high energy transfer efficiency is required both for operational economy and to avoid negative environmental impact of the system. An experimental electrified roadway test track built circa 1990 achieved 80% energy efficiency while recharging the battery of a prototype bus at a specially equipped bus stop. The bus could be outfitted with a retractable receiving coil for greater coil clearance when moving. The gap between the transmit and receive coils was designed to be less than 10 cm when powered. In addition to buses the use of wireless transfer has been investigated for recharging electric automobiles in parking spots and garages as well.
Some of these wireless resonant inductive devices operate at low milliwatt power levels and are battery powered. Others operate at higher kilowatt power levels. Current implantable medical and road electrification device designs achieve more than 75% transfer efficiency at an operating distance between the transmit and receive coils of less than 10 cm.
In 1995, Professor John Boys and Prof Grant Covic, of The University of Auckland in New Zealand, developed systems to transfer large amounts of energy across small air gaps. In 1998, RFID tags were patented that were powered in this way.
In November 2006, Marin Soljačić and other researchers at the Massachusetts Institute of Technology applied this near field behavior, well known in electromagnetic theory, the wireless power transmission concept based on strongly-coupled resonators. In a theoretical analysis, they demonstrate that, by designing electromagnetic resonators that suffer minimal loss due to radiation and absorption and have a near field with mid-range extent (namely a few times the resonator size), mid-range efficient wireless energy-transfer is possible. The reason is that, if two such resonant circuits tuned to the same frequency are within a fraction of a wavelength, their near fields (consisting of 'evanescent waves') couple by means of evanescent wave coupling (which is related to quantum tunneling). Oscillating waves develop between the inductors, which can allow the energy to transfer from one object to the other within times much shorter than all loss times, which were designed to be long, and thus with the maximum possible energy-transfer efficiency. Since the resonant wavelength is much larger than the resonators, the field can circumvent extraneous objects in the vicinity and thus this mid-range energy-transfer scheme does not require line-of-sight. By utilizing in particular the magnetic field to achieve the coupling, this method can be safe, since magnetic fields interact weakly with living organisms.
CHAPTER 1
INTRODUCTION
In this era of modernization, electricity has become the cup of life. A moment without electricity makes your thinking go dry. The major source of conventional form of electricity is through wires. The continuous research and development has brought forward a major breakthrough, which provides electricity without the medium of wires. This wonder baby is called WiTricity.
There are certain small but very useful discoveries made in history, which changed the world for ever, Newton’s gravitational law, Watt’s steam engine, Thomson’s bulb and many more. But a renaissance occurred with the invention of Electromagnetic Waves by Maxwell. Sir Jagdish Chandra Bose successfully generated electromagnetic waves having wavelength in the range of 5mm to 25 mm. Thereafter an Italian scientist named Marconi succeeded in transmitting electromagnetic waves up to a distance of several miles.
And with this there started a new era called WIRELESS TECHNOLOGY. Today, as we can see the word ‘wireless’ is common in day – to – day life. Wireless communication has made the world smaller. Almost each and everything is wireless or cordless. Cordless mouse, cordless keyboard, satellite communication, mobiles, cordless microphones and headphones, wireless internet service i.e. WIFI, etc. And these have definitely increased the standard of living.
In fact it dates back to the 19th century, when Nikola Tesla used conduction based systems instead of resonance magnetic fields to transfer wireless power. As it is in Radiative mode, most of the Power was wasted and has less efficiency. Further, in 2005, Dave Gerding coined the term WiTricity which is being used by the MIT researchers today.
Moreover, we all are aware of the use of electromagnetic radiation (radio waves) which is quite well known for wireless transfer of information. In addition, lasers have also been used to transmit energy without wires. However, radio waves are not feasible for power transmissions because the nature of the radiation is such that it spreads across the place, resulting into a large amount of radiations being wasted. And in the case of lasers, apart from requirement of uninterrupted line of sight (obstacles hinder the transmission process). It is also very dangerous
WiTricity is nothing but wireless electricity. Transmission of electrical energy from one object to another without the use of wires is called as WiTricity. WiTricity will ensure that the cell phones, laptops, iPods and other power hungry devices get charged on their own, eliminating the need of plugging them in. Even better, because of WiTricity some of the devices won't require batteries to operate.
Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all those devices typically rely on chemical energy storage(Battery) As they are becoming daily needs to present generation, Wire less energy transfer would be useful for many applications as above and they need midrange energy.
CHAPTER 2
LITERATURE REVIEW
In 2006 MIT researchers discovered a new method to provide electricity to remote objects without wires. Wiricity is based on coupled resonant objects. In 2007 researchers implemented a prototype using self resonant coils. In this first experiment they demonstrated efficient non-radiative power transfer over distance up to eight times the radius of the coils. This experiment was done using two copper coils. Each coil act as self resonant system. One of the coils is attached to the electricity source. Instead of irradiating the environment with electromagnetic waves, it fills the space with a non-radiative magnetic field oscillating at MHz frequencies. The non-radiative field mediates the power exchange with the other coil, which is specially designed to resonate with the field. The resonant nature ensures strong interaction between sending unit and receiving unit.
In the first experiment they successfully demonstrated the ability to power a 60W light bulb from a power source that was 2 meters away with 40% efficiency approximately. They used two capacitively loaded copper coils of 51 cm in diameter designed to resonate in the MHz range. One coil was connected to a power source, the other to a bulb. In this experiment the coils were designed to resonate at 10MHz. The setup powered the bulb oh even when the coils were not in line of sight. The bulb glowed even when wood, metal, and other devices were placed in between the coils.
Some disadvantages invoved in this technique is Wireless power transmission can be only in few meters, efficiency is about 40% only, As witricity is in development stage, lot of work is done for improving the efficiency and distance between transmitter and receiver.
Witricity has a bright future in providing wireless electricity. There are no limitations in witiricity power applications. Some of the potential applications are pwering of cell phones, laptops and other devices that normally run with the help of batteries or plugging in wires. Witricity applications are expected to work on the gadgets that are in close proximity to a source of wireless 'power, where in the gadgets charges automatically without necessarily, having to get plugged in. By the use of witricity there is no need of batteries or remembering to recharge batteries periodically. If a source is placed in each room to provide power supply to the
Wholehouse
Witricity has many medical applications. It is used for providing electric power in many commercially available medical implantable devices.
Another application of this technology includes transmission of information. It would not interfere with radio waves and it is cheap and efficient.
Wireless electricity (in short, witricity) is a recently developed technology for wireless power transfer . It has been demonstrated that it is feasible to transmit a significant amount of power at a high efficiency that has never been achieved previously. Despite this significant development, its effective transmission distance is limited by the size of the resonator. Relayed witricity power transfer system consists of at least three resonators (source, relay(s) and device) with the same resonant frequency, a driving loop, and an output loop. The source resonator is coupled inductively with the driving loop linked to an RF power source. Similarly, the device resonator is coupled inductively with the output loop to supply power to an external load. With the presence of the relay resonator, the device and source can interact more strongly, exchange energy more quickly and deliver power more efficiently when compared with the system without the relay resonator.[1]
CHAPTER 3
HISTORY OF WITRICITY
The idea of wireless generation and transmission of power is in experiment from a long time. The person who first paved the way of dreaming wireless power is NIKOLO TESLA. In 1888 he developed the principles of his Tesla coil and began working with his ideas for polyphase systems, which would allow transmission of AC electricity over large distances. The connection would be made by electrostatic induction or conduction through plasma. Tesla firmly believed that Wardenclyffe tower would permit wireless transmission and reception across large distances with negligible losses. But after lighting vacuum tubes wirelessly, he provided us with enough evidence of the potential and feasibility of wireless power transmission network. In 1902 Nikola Tesla patented a device, he called the device a "high-voltage, air-core, self-regenerative resonant transformer that generates very high voltages at high frequency"; it was a Tesla coil that transferred its energy using resonant transfer from the bottom coil a few feet through air to the top coil. This avoided arcing and permitted very high voltages to be created, and is one of the more common types built today.
Fig 3.1 Nikolo Tesla
In the early 1960s resonant inductive wireless energy transfer was used successfully in implantable medical devices including such devices as pacemakers and artificial hearts. While the early systems used a resonant receiver coil, later systems implemented resonant transmitter coils as well. These medical devices are designed for high efficiency using low power electronics while efficiently accommodating some misalignment and dynamic twisting of the coils. The separation between the coils in implantable applications is commonly less than 20 cm. Today resonant inductive energy transfer is regularly used for providing electric power in many commercially available medical implantable devices
Wireless electric energy transfer for experimentally powering electric automobiles and buses is a higher power application (>10 kW) of resonant inductive energy transfer. High power levels are required for rapid recharging and high energy transfer efficiency is required both for operational economy and to avoid negative environmental impact of the system. An experimental electrified roadway test track built circa 1990 achieved 80% energy efficiency while recharging the battery of a prototype bus at a specially equipped bus stop. The bus could be outfitted with a retractable receiving coil for greater coil clearance when moving. The gap between the transmit and receive coils was designed to be less than 10 cm when powered. In addition to buses the use of wireless transfer has been investigated for recharging electric automobiles in parking spots and garages as well.
Some of these wireless resonant inductive devices operate at low milliwatt power levels and are battery powered. Others operate at higher kilowatt power levels. Current implantable medical and road electrification device designs achieve more than 75% transfer efficiency at an operating distance between the transmit and receive coils of less than 10 cm.
In 1995, Professor John Boys and Prof Grant Covic, of The University of Auckland in New Zealand, developed systems to transfer large amounts of energy across small air gaps. In 1998, RFID tags were patented that were powered in this way.
In November 2006, Marin Soljačić and other researchers at the Massachusetts Institute of Technology applied this near field behavior, well known in electromagnetic theory, the wireless power transmission concept based on strongly-coupled resonators. In a theoretical analysis, they demonstrate that, by designing electromagnetic resonators that suffer minimal loss due to radiation and absorption and have a near field with mid-range extent (namely a few times the resonator size), mid-range efficient wireless energy-transfer is possible. The reason is that, if two such resonant circuits tuned to the same frequency are within a fraction of a wavelength, their near fields (consisting of 'evanescent waves') couple by means of evanescent wave coupling (which is related to quantum tunneling). Oscillating waves develop between the inductors, which can allow the energy to transfer from one object to the other within times much shorter than all loss times, which were designed to be long, and thus with the maximum possible energy-transfer efficiency. Since the resonant wavelength is much larger than the resonators, the field can circumvent extraneous objects in the vicinity and thus this mid-range energy-transfer scheme does not require line-of-sight. By utilizing in particular the magnetic field to achieve the coupling, this method can be safe, since magnetic fields interact weakly with living organisms.
