16-03-2011, 04:16 PM
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ABSTRACT:
The aim of this paper is to introduce a new system of transmitting the power which is called wireless electricity or witricity. Witricity is based upon coupled resonant objects to transfer electrical energy between objects without wires. The system consists of a Witricity transmitter (power source), and devices which act as receivers (electrical load). It is based on the principle of resonant coupling and microwave energy transfers. The action of an electrical transformer is the simplest instance of wireless energy transfer. There are mainly two types of transfers i.e. short range and long range transmission. The short range are of 2-3metres where as the long range are of few kilometers.
Wireless transmission is ideal in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible. The tangle of cables and plugs needed to recharge today's electronic gadgets could soon be a thing of the past. The concept exploits century-old physics and could work over distances of many metres. Consumers desire a simple universal solution that frees them from the hassles of plug-in chargers and adaptors. "Wireless power technology has the potential to deliver on all of these needs." However, transferring the power is the important part of the solution.
Witricity, standing for wireless electricity, is a term coined by MIT researchers, to describe the ability to provide electricity to remote objects without wires. Using self-resonant coils in a strongly coupled regime, efficient non-radiative power transfer over distances of up to eight times the radius of the coils can be done.. Unlike the conduction-based systems, Witricity uses resonant magnetic fields to reduce wastage of power. Currently the project is looking for power transmissions in the range of 100 watts.
With wireless energy transfer, the efficiency is a more critical parameter and this creates important differences from the wireless data transmission technologies. To avoid the conflicts like recharging and carrying its appliances of electrical and electronic devices, wireless power transmission is desirable. Wireless power transmission was originally proposed to avoid long distance electrical distribution based mainly on copper cables. This can be achieved by using microwave beams and the rectifying antenna, or rectenna, which can receive electromagnetic radiation and convert it efficiently to DC electricity. Researchers have developed several techniques for moving electricity over long distances without wires. Some exist only as theories or prototypes, but others are already in use. Magnetic resonance was found a promising means of electricity transfer because magnetic fields travel freely through air yet have little effect on the environment or, at the appropriate frequencies, on living beings and hence is a leading technology for developing witricity
HOW IT WORKS-
Wireless light: Researchers used magnetic resonance coupling to power a 60-watt light bulb. Tuned to the same frequency, two 60-centimeter copper coils can transmit electricity over a distance of two meters, through the air and around an obstacle.
The researchers built two resonant copper coils and hung them from the ceiling, about two meters apart.
When they plugged one coil into the wall, alternating current flowed through it,
Creating a magnetic field.
The second coil, tuned to the same frequency and hooked to a light bulb, reso¬nated with the magnetic field, generating an electric current that lit up the bulb--even with a thin wall between the coils.
How wireless energy could work-
"Resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. Two resonant objects of the same frequency tend to couple very strongly." Resonance can be seen in musical instruments for example. "When you play a tune on one, then another instrument with the same acoustic resonance will pick up that tune, it will visibly vibrate,"
Instead of using acoustic vibrations, system exploits the resonance of electromagnetic waves. Electromagnetic radiation includes radio waves, infrared and X-rays. Typically, systems that use electromagnetic radiation, such as radio antennas, are not suitable for the efficient transfer of energy because they scatter energy in all directions, wasting large amounts of it into free space.
To overcome this problem, the team investigated a special class of "non-radiative" objects with so-called "long-lived resonances". When energy is applied to these objects it remains bound to them, rather than escaping to space. "Tails" of energy, which can be many metres long, flicker over the surface. If another resonant object is brought with the same frequency close enough to these tails then it turns out that the energy can tunnel from one object to another.
Hence, a simple copper antenna designed to have long-lived resonance could transfer energy to a laptop with its own antenna resonating at the same frequency. The computer would be truly wireless. Any energy not diverted into a gadget or appliance is simply reabsorbed. The systems that are described would be able to transfer energy over three to five metres. This
ABSTRACT:
The aim of this paper is to introduce a new system of transmitting the power which is called wireless electricity or witricity. Witricity is based upon coupled resonant objects to transfer electrical energy between objects without wires. The system consists of a Witricity transmitter (power source), and devices which act as receivers (electrical load). It is based on the principle of resonant coupling and microwave energy transfers. The action of an electrical transformer is the simplest instance of wireless energy transfer. There are mainly two types of transfers i.e. short range and long range transmission. The short range are of 2-3metres where as the long range are of few kilometers.
Wireless transmission is ideal in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible. The tangle of cables and plugs needed to recharge today's electronic gadgets could soon be a thing of the past. The concept exploits century-old physics and could work over distances of many metres. Consumers desire a simple universal solution that frees them from the hassles of plug-in chargers and adaptors. "Wireless power technology has the potential to deliver on all of these needs." However, transferring the power is the important part of the solution.
Witricity, standing for wireless electricity, is a term coined by MIT researchers, to describe the ability to provide electricity to remote objects without wires. Using self-resonant coils in a strongly coupled regime, efficient non-radiative power transfer over distances of up to eight times the radius of the coils can be done.. Unlike the conduction-based systems, Witricity uses resonant magnetic fields to reduce wastage of power. Currently the project is looking for power transmissions in the range of 100 watts.
With wireless energy transfer, the efficiency is a more critical parameter and this creates important differences from the wireless data transmission technologies. To avoid the conflicts like recharging and carrying its appliances of electrical and electronic devices, wireless power transmission is desirable. Wireless power transmission was originally proposed to avoid long distance electrical distribution based mainly on copper cables. This can be achieved by using microwave beams and the rectifying antenna, or rectenna, which can receive electromagnetic radiation and convert it efficiently to DC electricity. Researchers have developed several techniques for moving electricity over long distances without wires. Some exist only as theories or prototypes, but others are already in use. Magnetic resonance was found a promising means of electricity transfer because magnetic fields travel freely through air yet have little effect on the environment or, at the appropriate frequencies, on living beings and hence is a leading technology for developing witricity
HOW IT WORKS-
Wireless light: Researchers used magnetic resonance coupling to power a 60-watt light bulb. Tuned to the same frequency, two 60-centimeter copper coils can transmit electricity over a distance of two meters, through the air and around an obstacle.
The researchers built two resonant copper coils and hung them from the ceiling, about two meters apart.
When they plugged one coil into the wall, alternating current flowed through it,
Creating a magnetic field.
The second coil, tuned to the same frequency and hooked to a light bulb, reso¬nated with the magnetic field, generating an electric current that lit up the bulb--even with a thin wall between the coils.
How wireless energy could work-
"Resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. Two resonant objects of the same frequency tend to couple very strongly." Resonance can be seen in musical instruments for example. "When you play a tune on one, then another instrument with the same acoustic resonance will pick up that tune, it will visibly vibrate,"
Instead of using acoustic vibrations, system exploits the resonance of electromagnetic waves. Electromagnetic radiation includes radio waves, infrared and X-rays. Typically, systems that use electromagnetic radiation, such as radio antennas, are not suitable for the efficient transfer of energy because they scatter energy in all directions, wasting large amounts of it into free space.
To overcome this problem, the team investigated a special class of "non-radiative" objects with so-called "long-lived resonances". When energy is applied to these objects it remains bound to them, rather than escaping to space. "Tails" of energy, which can be many metres long, flicker over the surface. If another resonant object is brought with the same frequency close enough to these tails then it turns out that the energy can tunnel from one object to another.
Hence, a simple copper antenna designed to have long-lived resonance could transfer energy to a laptop with its own antenna resonating at the same frequency. The computer would be truly wireless. Any energy not diverted into a gadget or appliance is simply reabsorbed. The systems that are described would be able to transfer energy over three to five metres. This
