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21-02-2010, 12:05 PM
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witricity full report

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Seminar Report
WITRICITY
ABSTRACT
The technology used for wireless power transmission is known as witricity. Wireless power transmission is not a new idea, Nikola Tesla proposed theories of wireless power transmission in the late 1800s and early 1900s. Tesla's work was impressive, but it did not immediately lead to wide spread practical methods for wireless power transmission. Since then many 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. In 2006 researchers at Massachusetts Institute of Technology led by Marine Soijacic discovered an efficient way to transfer power between coils separated by a few meters. They have dubbed this technology as witricity. Witricity is based upon coupled resonant objects. Two resonant objects of the same resonant frequency tend to exchange energy efficiently, while not interchanging the surroundings. The researchers demonstrate the ability to transfer 60W with approximately 40% efficiency over distance in excess of 2 meters. Currently the project is looking for power transmission in the range of 100watts. As witricity is in the development stage, lots of work is to be done in improving the range of power transmission and efficiency.
INTRODUCTION
If we are particularly organized and good with tie wrap then also a few dusty power cord tangles around our home. We have even had to follow one particular cord through the seemingly impossible snarl to the outlet hoping that the plug pull will be the right one. This is one of the downfalls of electricity. While it can make people's lives easier, it can add a lot of clutter in the process. For these reasons, scientists have tried to develop methods of wireless power transmission that could cut the clutter or lead to clean sources of electricity. Wireless power transmission is not a new idea. Many researchers developed several methods for wireless power transmission. But witricity is a new technology used for wireless power transmission. By the use of this technology transmission of electrical energy to remote objects without wires can be possible. The inventors of witricity are the researchers from Massachusetts Institute of Technology (MIT). They developed a new technology for wireless electricity transmission and this is based upon the coupled resonant objects. In this resonant magnetic fields are used. So the wastage of power is reduced. The system consists of witricity transmitters and receivers. The transmitters and receivers contain magnetic loop antennas made of copper coils and they are tuned to the same frequency.
METHODS USED FOR WIRELESS POWER TRANSMISSION
INDUCTION (INDUCTIVE COUPLING):
This is the first method used for wireless power transfer. The simplest example for wireless energy transfer using this method is the electrical transformer. In this the primary and secondary circuits are
electrically isolated from each other. The transfer of energy takes place by electromagnetic coupling through mutual induction. The main draw back of this method is the short range. For efficient working of a system which uses this method, the receiver must be in very close proximity to the-transmitter. A larger, stronger field can be used for energy transfer over lorjg distance, but this process is extremely inefficient. Since magnetic field spreads in all direction, making a large wastage of energy.
RESONANT INDUCTION (EVANESCENT WAVE COUPLING)
In 2006 MIT researchers discovered an efficient method to transfer power between coils separated by few meters. They extend the distance between coils in inductive coupling system by adding resonant. They demonstrated by sending electromagnetic waves around in a highly angular waveguide, evanescent waves are produced, which carry no energy. An evanescent wave is a near field standing wave exhibiting exponential decay with distance. Evanescent waves are always associated with matter, and are most intense within one-third wavelength from any radio antenna. Evanescent means tends to vanish, the intensity of evanescent waves decays exponentially with the distance from the interface at which they are formed. If a proper resonant waveguide is brought near the transmitter, the evanescent waves can allow the energy to tunnel to the power drawing wave guide. Since the electromagnetic waves would tunnel, they would not propagate through the air to be absorbed or dissipated and would not disrupt .electronic devices or cause physical injury like microwave or radio waves transmission.
In resonant induction method induction can take place a little differently if the electromagnetic fields around the coils resonate at the same frequency. In this a curved coils of wire uses as an inductor. A capacitance plate which can hold a charge attaches to each end of the coil. As electricity travels through this coil the coil begins to resonate. Its resonant frequency is a product of the inductance of the coil and the capacitance of the piate. Unlike multiple layer secondary of non-resonant transformer single layer solenoids with closely spaced capacitor plates on each end as shown in figure 1 is used as transmitter and receiver.
Inductor Coil t
Capacitance Plate
©2O07 HawStufltfAxtta
Fig. 1
The MIT wireless power project uses a curved coil and capacitive plates.
Fig. 2
Electricity traveling along an electromagnetic wave can tunnel from one coil to the other as long as the both have the same resonant frequency. As long as both the coils are out of range of one another nothing will happen, since the field around the coil are not strong enough to affect much around them. Similarly if two coils resonate at different frequencies nothing will happen. Figure 2 shows the working of wireless power transmission.
By using resonant induction one coil can send electricity to several receiving coils as long as they all resonate at same frequency. The MIT team's preliminary work suggests that kind of setup could power or recharge all the devices in one room. Some modifications would be necessary to send power over long distances, like the length of a building or a city.
¦ Fig. 3
The figure 3 shows that a single transmitter can be used to charge several devices in a room.
The concept of witricity was made possible using resonance, where an object vibrates with the application Of a certain frequency of energy. So two objects having similar resonance tend to exchange energy without causing any effect on the surrounding objects. To under stand the energy transfer using resonant method consider an example involves acoustic resonances. Imagine a room with 100 identical wine glasses, each filled with wine up to a different level, so they all have different resonant frequencies. This is because objects physical structure determines the resonant frequency. The frequency at which an object naturally vibrates is called resonant frequency. If a singer sings loudly inside the room, a glass of corresponding frequency might accumulate sufficient energy to even explode,
while not influencing the other. In all the system of coupled resonators there exists a strongly coupled regime of operation. These considerations are universal, applying to all kinds of resonances. MIT researchers focused on magnetically coupled resonators and thus wireless power transmission over few meters are possible. This method is one million times as efficient as electromagnetic induction systems. This method is also called non-radiative energy transfer, since it involves stationary fields around the coils rather than fields that spread in all direction.
RADIO AND MICROWAVE
If resonance is incorporated or not, induction generally sends wireless power over relatively short distance. For very long distance power transmission radio and microwaves are used. Japanese researcher YAGI developed a directional array antenna known as YAGI antenna for wireless energy transmission. It is widely used for broadcasting and wireless telecommunications industries. While it did not prove to be particularly useful for power transmission. Power transmission via radio waves can be made more directional, allowing longer distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A rectenna is a rectifying antenna, an antenna used to convert microwaves into DC power. Being that an antenna refers to any type of device that converts electromagnetic waves into electricity or vice versa. A rectenna is simply a microwave antenna. Inverse rectennas convert electricity into microwave beams, rectennas suitable for receiving energy beamed from solar panels in geocentric orbit would need to be several miles across. Although power densities of such an arrangement would be low enough to avoid any damage to people or the environment. Rectifying antennae are usually made an array of dipole antennae, which have positive and negative poles. These antennae connect to semiconductor diodes. Rectenna conversion has an efficiency of about 95%.
In the 1980s, Canada's Communications Research
Centre created a small airplane that could run off power beamed from the
Dept. ofEEE - 6- SNGCE, Kolenchery
Earth. The unmanned plane, called the Stationary High Altitude Relay Platform (SHARP), was designed as a communications relay. Rather flying from point to point, the SHARP could fly in circles two kilometers in diameter at an altitude of about 13 miles (21 kilometers). Most importantly, the aircraft could fly for months at a time.
Fig. 4
The secret to the SHARP'S long flight time was a large, ground-based microwave transmitter. The SHARP'S circular flight path kept it in range of this transmitter. A large, disc-shaped rectifying antenna, or rectenna, just behind the plane's wings changed the microwave energy from the transmitter into direct-current (DC) electricity. Because of the microwaves interaction with the rectenna, the SHARP had a constant power supply as long as it was in range of a functioning microwave array. This arrangement functions according to the following procedure.
1. Microwaves, which are part of the electromagnetic spectrum, reach the dipole antennae.
2. The antennae collect the microwave energy and transmit it to the diodes.
3. The diodes act like switches that are open or closed as well as turnstiles that let electrons flow in only one direction. They direct the electrons to the rectenna's circuitry.
4. The circuitry routes the electrons to the parts and systems that need them.
Micro wave power transmission has some drawbacks:
» The solar power stations on the moon would require supervision and maintenance. In other words, the project would require sustainable, manned moon bases.
¢ Only part of the earth has a direct line of sight to the moon at any given time. To make sure the whole planet had a steady power supply, a network of satellites would have to re-direct the microwave energy.
¢ Many people would resist the idea of being constantly bathed in microwaves from space, even if the risk were relatively low.
LASER
Laser beams can be used for wireless power transmission. Power can be transmitted by converting electricity into laser beam. At the receiving side a solar cell receiver is used. But it has many drawbacks, they are given below
1. Conversion to light, such as with a laser, is moderately inefficient
2. Conversion back into electricity is moderately inefficient, with photovoltaic cells achieving 40%-50% efficiency
3. Atmospheric absorption causes losses.
4. This method requires a direct line of sight with the target.
WITRICITY IN HISTORY
Wireless power transmission is not a new idea. Nickola Tesla demonstrated transmission of electrical energy without wires in early 19th century. Tesla used electromagnetic induction systems. William C Brown demonstrated a micro wave powered model helicopter in 1964. This receives all the power needed for flight from a micro wave beam. In 1975 Bill Brown transmitted 30kW power over a distance of 1 mile at 84% efficiency without using cables. Researchers developed several technique for moving electricity over long distance without wires. Some exist only as theories or prototypes, but others are already in use.
Consider an example, in this electric devices recharging without any plug-in. The device which can be recharged is placed on a charger. Supply is given to the charger and there is no electrical contact between charger and device. The recharging takes place in following steps. 1. Current from the wall outlet flows through a coil inside the charger, creating a magnetic field. In a transformer, this coil is called the primary winding.
2. When the device placed on the charger, the magnetic field induces a current in another coil, or secondary winding, which connects to the battery.
3. This current recharges the battery.
Figure 6 shows an electric tooth brush's cut section. In consists of two windings primary and secondary. The primary winding is in the charger and the secondary winding is in the tooth brush. Figure 7 shows a camera and mobile placed on a charger for charging. By the use of this one or more devices can be charged at the same time.
An electric toothbrush's base
and handle contain coils that to
allow the battery to recharge
A Splash power mat uses induction recharge multiple devices Simultaneously
WITRICITY AT PRESENT
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.
Effect of using capacitively-loaded loops and lowering the operating frequency on field strengths and power levels.
Capacitively loaded loops generate significantly lower electric fields in the space surrounding the objects than self-resonant coils. The calculations to simulate a transfer of 60W across two identical capacitively-loaded loops similar in dimension to our self-resonant coils
(radius of loop 30cm, cross sectional radius of the conductor 3cm, and distance between the loops of 2m), and calculated the maximum values of the fields and Poynting Vector 20cm away from the device loop.
Erms Hrms Srms Power
Frequency(MHz) Efficiency {Vim) (A/m) (W/cm2) radiated(W)
10 83% ' 185 21 0.08 3.3
1 60% 40 14 0.04 0.005
At 10MHz, note the significant reduction in the electric field strength with respect to the self resonant coils. Lowering the operating frequency down to 1MHz further reduces the electric field, Poynting vector, and power radiated. At 1MHz, all our fields are below IEEE safety guidelines (Erms =614V/m, Hrms = 16.3A/m and Srms = 0.1 W/cm2 at 1MHz)
The figure given below shows the experimental setup. In which the transmitter and receiver coils are separated at a distance of 2m. The bulb connected to receiver coils is glowed when supply is given to transmitter coil as shown in figure. In the first figure transmitter and receiver coils are in direct line of sight. If a wooden piece is placed in between transmitter and receiver coils then also power transmission is possible.
Theoretical-and experimental K, as a function of distance when one of the coils is rotated by 45% with respect to coaxial alignment.
o o
I Fig. 13
I Alternative geometry.
ADVANTAGES OF WITRICITY
1. No need of line of sight - In witricity power transmission there is any ;
need of line of sight between transmitter and receiver. That is power !
transmission can be possible if there is any obstructions like wood,
metal, or other devices were placed in between the transmitter and
receiver.
2. No need of power cables and batteries - Witricity replaces the use of power cables and batteries.
3. Does not interfere with radio waves
4. Wastage of power is small - Electromagnetic waves would tunnel, they
would not propagate through air to be absorbed or dissipated. So the
wastage is small.
5. Negative heaiih implications - By the use of resonant coupling wave
lengths produced are far lower and thus make it harmless.
6. Highly efficient than electromagnetic induction - Electro magnetic induction system can be used for wireless energy transfer only if the primary and secondary are in very close proximity. Resonant induction system is one million times as efficient as electro magnetic induction system.
7. Less costly - The components of transmitter and receivers are cheaper. So this system is less costly.
DISADVANTAGES
1. Wireless power transmission can be possible only in few meters.
2. Efficiency is only about 40%.
As witricity is in development stage, lot of work is done for improving the efficiency and distance between transmitter and receiver.
APPLICATIONS
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 whole house
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.
CONCLUSION
Witricity is in development stage, lots of work is to be done to use it for wireless power applications. Currently the project is looking for power transmission in the range of 100w. Before the establishment of this technology the detailed study must be done to check whether it cause any harm on any living beings.
REFERENCES
1. Sasthra Keralam magazine
2. Witricitypower.com
3. http://en.wikipedia.org
4. TreeHugger.com
5. http://www.howstuffworks.com
16-10-2010, 03:08 PM
Post: #2
RE: witricity full report

Submitted By
RADHIKA,NAVATHA


.ppt  witricity.ppt (Size: 1.64 MB / Downloads: 1334)


History of Wireless Power:
In 1899, Sir Nikola Tesla Proposed a method of Wireless Power Transmission.
As it is in Radiative mode, most of the Power was wasted and has less efficiency.
The efficient midrange power transfer concept is Witricity. In this model source and load are in Magnetic resonance so there is no power loss.

Need of Witricity:
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.
18-10-2010, 10:31 AM
Post: #3
RE: witricity full report

.doc  wire less current.doc (Size: 554.5 KB / Downloads: 630)
This article is presented by:
E.NAVEEN KUMAR.
D.ARUN KUMAR REDDY
INTELL ENGINEERING COLLEGE ANANTAPUR
The Wireless Electricity


ABSTRACT:
Can we imagine the life without electrical wires? From now answer to this question is yes. The method proposed in the present paper called “Witricity “will facilitate to Transfer power without using wires. The efficient midrange power can be transmitted to any device which uses that range of power by the technique used in this Witricity concept.
Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all the above devices typically rely on chemical energy storage(Battery) .As they are becoming daily needs to present generation, Wireless energy transfer would be useful for many applications as above and they need midrange energy. This is the main reason to prepare this paper.
When two Magnetically Resonating objects at “Strongly coupled” regime tend to exchange energy efficiently by transfer of power in the non-radiating fields. This is the basic principle involved in it. By taking two coils having same magnetic resonance and one is coupled to source and other is coupled to Device. So that the energy transfer is efficient even the air gap between them is high.
This paper describes the basic history of wireless power transmission, what are Magnetic resonance and Strongly coupled regime, Experimental design, Range and rate of coupling (coupling calculations) and Design of parameters and Simulation for variation of power with and without the external object between source and load.
Historyof Wireless power:
Wireless power transmission is not new for us. Various methods of Transmitting power wirelessly have been known for centuries. In 1899, Sir Nikola Tesla proposed a method to transmit energy over long distances wirelessly using ElectroMagnetic radiation principle, but such radiation is excellent for wireless transmission of Information, it is not feasible to Power transmission.
29-10-2010, 05:04 PM
Post: #4
RE: witricity full report

.ppt  Witricity.ppt (Size: 2.3 MB / Downloads: 845)
WITRICITY

Presentation By: Santosh Lopez
Nilesh Naik


ABSTRACT:-


Wireless power transmission is witricity
Nikola Tesla proposed theories of Witricity in the late 1800s and early 1900s
In 2006 researchers at MIT led by Marine discovered an efficient way to transfer power between coils separated by a few meters.
Two resonant objects of the same resonant frequency tend to exchange energy efficiently, while not interchanging the surroundings
23-12-2010, 02:40 PM
Post: #5
RE: witricity full report
Prepared by:Ankit Mittal


.ppt  ankit report witricity.ppt (Size: 1.62 MB / Downloads: 805)

Witricity
Wireless- Wireless communication is the transfer of information over a distance without the use of enhanced electrical conductors or "wires". The distances involved may be short (a few meters as in television remote control) or long (thousands or millions of kilometers for radio communications).
SAN – Storage Area Network
Seminar Report by:-
Name - Aditi Malik
Roll No.- 072903100
Branch - Electronics and communication
Witricity - Wireless Electricity
Wireless Electricity-Wireless energy transfer or Wireless Power is the process that takes place in any system where electrical energy is transmitted from a power source to an electrical load without interconnecting wires. Wireless transmission is useful in cases where instantaneous or continuous energy transfer is needed but interconnecting wires are inconvenient, hazardous, or impossible
Wireless energy transfer is different from wireless transmission of information, such as radio, where the signal-to-noise ratio (SNR) or the percentage of power received becomes critical only if it is too low to adequately recover the signal. With wireless power transmission, efficiency is the more important parameter
The first mover and innovator
Nikola Tesla was the first to Experiment with
wireless electricity, but ultimately failed after
losing his key financial backing in the late 1800

There are certain small but very useful discoveries made in history, which changed the world forever, 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.

Tesla began working with Thomas Edison, but the two men were worlds apart in both their science and cultures (the fact that Tesla's alternating-current concept posed a direct threat to sales of Edison's direct-current devices probably didn't help) and they soon went their separate ways.

Tesla invented the alternating-current generator that provides your light and electricity, the transformer through which it is sent, and even the high voltage coil of your picture tube.
Early Visions Of wireless Power
Nikola Tesla’s Wardenclyffe tower built on Long Island, NY in 1904 . The tower was destroyed in 1917.

Nikola Tesla’s Wardenclyffe toer built on long Island , NY in 1904 was destroy in 1917.
As this tower are build up to transfer wireless electricity and suppose to transfer electric power any where on earth . They are suppose to place near the north pole of Earth . This stuff works that time but stop due to security purpose and due to financially problem.
We Human Love Electricity
Trillion Of Towers Around Us
Batteries
40 Billion Disposable Batteries / Yr.
What Happen To This Batteries After Use
Batteries Disintegrate and end up here.
The forgotten invention is reborn in 2007
The idea of wireless electricity has been around since the early days of the Tesla coil. But thanks to a group of MIT scientists, "WiTricity" (as these scientists call it) is now one step closer to practical reality.


How It Works
They Power up 60W Electric Bulb From a Power Source 7 feet away

The experimental design was constituted of two copper coils, each a self resonant system . One of the coil connected to an AC power called resonant source. The other coil called , the resonant capture device was connected to light bulb.
The power source and capture devise was suspended in mid-air with nyclon thread at a distance that range from few cm to 2.5 meter.
At the resonant source the standard 60 hz current convert to 10Mhz and feed into transmitting coil. The oscillating current in transmitting coil cause the coil to emit a 10 Mhz field. As the capture coil is of same dimension and it is in resonate with the source coil at same frequency called magnetic induction, pick up the energy from source coil magnetic field.
So this magnetic field induce current in the capture coil, light the bulb.
They got 50 % efficiency , buy the way that’s still a couple of time more efficient then a battery could be to do same thing .

Witricity Technology : The Basics
Electricity: The flow of electrons (current) through a conductor (like a wire), or charges through the atmosphere (like lightning).  A convenient way for energy to get from one place to another!
WiTricity technology is—transferring electric energy or power over distance without wires .With the basics of Electricity and Magnetisum

Magnetism:
A fundamental force of nature, which causes certain types of materials to attract or repel each other . Permanent magnets, like the ones on your refrigerator and the earth’s magnetic field, are examples of objects having constant magnetic fields.
Oscillating magnetic fields vary with time, and can be generated by alternating current (AC) flowing on a wire. The strength, direction, and extent of magnetic fields are often represented and visualized by drawings of the magnetic field lines.

Electromagnetism:
A term for the interdependence of time-varying electric and magnetic fields. For example, it turns out that an oscillating magnetic field produces an electric field and an oscillating electric field produces a magnetic field.


Magnetic Induction:
A loop or coil of conductive material like copper, carrying an alternating current (AC), is a very efficient structure for generating or capturing a magnetic field.

Energy/Power Coupling:
Energy coupling occurs when an energy source has a means of transferring energy to another object. One simple example is a locomotive pulling a train car—the mechanical coupling between the two enables the locomotive to pull the train, and overcome the forces of friction and inertia that keep the train still—and, the train moves. Magnetic coupling occurs when the magnetic field of one object

Resonance:
Resonance is a property that exists in many different physical systems. It can be thought of as the natural frequency at which energy can most efficiently be added to an oscillating system
WiTricity Technology:
WiTricity power sources and capture devices are specially designed magnetic resonators that efficiently transfer power over large distances via the magnetic near-field. These proprietary source and device designs and the electronic systems that control them support efficient energy transfer over distances that are many times the size of the sources/devices themselves.
How It Works
Imagine a coil there is a capacitor to it too.
And if u can cause that coil to resonate, what will happen , it pulse at alternating frequency , at fierily high frequency.
And if u can bring another coil , close enough to source that will only work exactly at resonate frequency , you can actually get them to what is called strongly couple and transfer energy between them

Theoretically one stationary coil in a room could power multiple devices with receiving coils .
No more messy wires, and with widespread enough use it could even eliminate costly batteries.
What About Safety?
Non-radiative power transfer – Uses magnetic near field

Magenetic fields are safe for people and animals

Heighly resonant coupling minimizes energy transfer to “ off- resonant” objects

Witricity systems are designed to meet in its all safety guidelines
WiTricity Applications
Direct Wireless Power—when all the power a device needs is provided wirelessly, and no batteries are required. This mode is for a device that is always used within range of its WiTricity power source

Automatic Wireless Charging—when a device with rechargeable batteries charges itself while still in use or at rest, without requiring a power cord or battery replacement. This mode is for a mobile device that may be used both in and out of range of its WiTricity power source.
Features and Benefits
Highly Resonant Strong Coupling-High Efficiency Over Distance
Energy Transfer via Magnetic Near Field-Penetrates and Wraps-Around Obstacles
Non- Radiative Energy Transfer -Safe for People and Animals
Scalable Design-From Milli watts to Kilowatts
Flexible Geometry-Devices That Can Fit Into OEM Products
WiTricity’s technology is more than… Traditional Magnetic Induction
WiTricity’s technology is different than… Radiative Power Transfer
WiTricity’s technology is different than… Magnetic Resonance Imaging(MRI)


Highly Resonant Strong Coupling Provides High Efficiency Over Distance -WiTricity's mode of wireless power transfer is highly efficient over distances ranging from centimeters to several meters. We define efficiency as the amount of usable electrical energy that is available to the device being powered, divided by the amount of energy that is drawn by the WiTricity source. In many applications, efficiency can exceed 90%. And WiTricity sources only transfer energy when it is needed. When a WiTricity powered device no longer needs to capture additional energy, the WiTricity power source will automatically reduce its power consumption to a power saving “idle” state

Energy Transfer via Magnetic Near Field Can Penetrate and Wrap Around Obstacles -The magnetic near field has several properties that make it an excellent means of transferring energy in a typical consumer, commercial, or industrial environment.  Most common building and furnishing materials, such as wood, gypsum wall board, plastics, textiles, glass, brick, and concrete are essentially “transparent” to magnetic fields—enabling WiTricity technology to efficiently transfer power through them.  In addition, the magnetic near field has the ability to “wrap around” many metallic obstacles that might otherwise block the magnetic fields.


Non-Radiative Energy Transfer is Safe for People and Animals -WiTricity’s technology is a non-radiative mode of energy transfer, relying instead on the magnetic near field. Magnetic fields interact very weakly with biological organisms—people and animals—and are scientifically regarded to be safe. Professor Sir John Pendry of Imperial College London, a world renowned physicist, explains:  “The body really responds strongly to electric fields, which is why you can cook a chicken in a microwave.  But it doesn't respond to magnetic fields. As far as we know the body has almost zero response to magnetic fields in terms of the amount of power it absorbs."  Evidence of the safety of magnetic fields is illustrated by the widespread acceptance and safety of household magnetic induction cooktops.  
Through proprietary design of the WiTricity source, electric fields are almost completely contained within the source. This design results in levels of electric and magnetic fields which fall well within regulatory guidelines. Thus WiTricity technology doesn’t give rise to radio frequency emissions that interfere with other electronic devices, and is not a source of electric and magnetic field levels that pose a risk to people or animals. 
Scalable Design Enables Solutions from milliwatts to Kilowatts -WiTricity systems can be designed to handle a broad range of power levels. The benefits of highly efficient energy transfer over distance can be achieved at power levels ranging from milliwatts to several kilowatts

WiTricity’s technology is more than… -Traditional Magnetic Induction -The power exchange efficiency of some induction systems is improved by utilizing resonant circuits. These so-called resonantly enhanced induction techniques are used in certain medical implants and high-frequency RFIDs for example.

WiTricity’s technology is different than… Radiative Power Transfer -WiTricity’s technology for power transfer is non-radiative and relies on near-field magnetic coupling. Many other techniques for wireless power transfer rely on radiative techniques, either broadcasted or narrow beam (directed radiation) transmission of radio, or light waves.

WiTricity’s technology is different than… Magnetic Resonance Imaging(MRI) -Many people assume that WiTricity’s “Resonant Magnetic Coupling” must be similar to magnetic resonance imaging (MRI) technology, however, the technologies are similar in name only.  MRI is, as its name suggests, a technology for using magnetism as a basis for diagnostic imaging of soft tissue in the human body. It utilizes a strong DC magnet to orient the magnetic fields of atoms within tissues, and radio frequency fields to manipulate those atoms in a selective way, so that tissues and structures can be imaged clearly. The “resonance” referred to in “MRI” refers to the resonance of atomic structures. MRI is not considered to be a method for wireless power transfer.
PROs
Less accidents and instances of electrocution
Convenient to users who use products that can be charged through WiTricity
Could eliminate the need for an inefficient, costly, and capital intensive grid of cables, towers and substations
Gateway to other break through technological advances
Eliminate mess of cords and power strips used to charge products
Your home would keep your gadgets constantly powered up
Could eliminate batteries
Magnetic fields have little affect on biological organisms – but still needs more testing
23-02-2011, 01:53 AM
Post: #6
RE: witricity full report
Please can u send me full report on witricity....
I am interested in witricity and ll give the same as tech seminar, please send me complete report(abstract,PPT,report) to my mail
27-02-2011, 10:20 AM
Post: #7
RE: witricity full report
hi............... Iam Geethanjali..B.Tech IV year student... please suggest a new technical topic for thechnical seminar...
07-03-2011, 07:47 PM
Post: #8
RE: witricity full report
please dear send me report on witricity.
08-03-2011, 01:43 PM
Post: #9
RE: witricity full report
PRESENTED BY
D.SANDEEP KUMAR


.doc  A SEMINOR ON WITRICITY.doc (Size: 1.14 MB / Downloads: 375)
ABSTRACT
Human brains always search for the new ways and means which makes life easy and simple. Over the past years great scientists invented great things which changed the world completely and effectively. Even then the thrust for the new inventions was not fulfilled.
So many new things are dumped in to the market time-to-time. Among those electronic gadgets have major share. Now a days our life depends much on electronic devices. All these devices have different cables and pins for their operation. We have to insert those cables in the sockets for the supply and also some times to recharge some of the devices.
Let us take an example as cell phone. We have to charge it time to time other wise it will be switched off. So we use a cable to charge it. If we forget that we will loss some thing. Similarly all the electronic gadgets depend on cables for their operation.
Imagine if all the gadgets take care of themselves and become independent of cables. It will be a great and very useful thing to implement. A professor from MIT named MARIN SOLJACIC had this wonderful thought and with the help of some other members found one interesting concept called WITRICITY. Witricity is a portmanteau for wireless electricity. This concept laid the way to get rid of the wires and cables.
INTRODUCTION
Electricity is today a necessity of modern life. It is difficult to imagine passing a day without electricity. The conventional use of electricity is made possible through the use of wires. However researchers in MIT have devised a means of providing electricity without any wires.
These researchers coined the term WITRICITY, which is basically a portmanteau for wireless electricity. This principle of wireless electricity works on the principle of using coupled resonant objects for the transference of electricity to objects without the use of any wires. A Witricity system consists of a Witricity transmitter and another device called the receiver.
The receiver works on the same principle as radio receivers where the device has to be in the range of the transmitter. It is with the help of resonant magnetic fields that Witricity produces electricity, while reducing the wastage of power. This is unlike the principle adopted by Nikola Tesla in the later part of the 19th century; where conduction based systems were used. The present project on Witricity aims at power transmissions in the range of 100 watts. May be the products using WITRICITY in future might be called Witric or Witric's.
So far the MIT researchers have been able to power a 60 watt light bulb from a power source that is located about seven feet away, while providing forty percent efficiency. This was made possible using two copper coils that were twenty inches in diameter which were designed so that they resonated together in the MHz range. One of these coils were connected to a power source while the other, to a bulb. With this witricity setup, the bulb got powered even when the coils were not in sight.
Resonant induction:
In November 2006, Marin Soljacic and other researchers at the Massachusetts Institute of Technology applied the near field behavior well known in electromagnetic theory to a wireless power transmission concept based on strongly-coupled resonators. In a theoretical analysis (see Ref: Annals of Physics), 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 objects are brought in mid-range proximity, their near fields (consisting of so-called 'evanescent waves') couple (evanescent wave coupling) and can allow the energy to tunnel/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.
1) Power from mains to antenna, which is made of copper
2) Antenna resonates at a frequency of 6.4MHz, emitting electromagnetic waves
3) 'Tails' of energy from antenna 'tunnel' up to 5m (16.4ft)
4) Electricity picked up by laptop's antenna, which must also be resonating at 6.4MHz. Energy used to re-charge device
5) Energy not transferred to laptop re-absorbed by source antenna. People/other objects not affected as not resonating at 6.4MHz
On June 7, 2007, it was reported that a prototype system had been implemented. In an experimental demonstration (see Ref: Science), the MIT researchers successfully demonstrated the ability to power a 60-watt light bulb wirelessly using two copper coils of 60cm diameter that were 2m (7ft) away at roughly 45% efficiency. The coils were designed to resonate together at 10MHz and were oriented along the same axis. One was connected inductively to a power source, and the other one to a bulb. The setup powered the bulb on, even when the direct line of sight was blocked using a wooden panel.
"Resonant inductive coupling" has key implications in solving the two main problems associated with non-resonant inductive coupling and electromagnetic radiation, one of which is caused by the other; distance and efficiency. Electromagnetic induction works on the principle of a primary coil generating a predominantly magnetic field and a secondary coil being within that field so a current is induced within its coils. This causes the relatively short range due to the amount of power required to produce an electromagnetic field. Over greater distances the non-resonant induction method is inefficient and wastes much of the transmitted energy just to increase range. This is where the resonance comes in and helps efficiency dramatically by "tunneling" the magnetic field to a receiver coil that resonates at the same frequency. Unlike the multiple-layer secondary of a non-resonant transformer, such receiving coils are single layer solenoids with closely spaced capacitor plates on each end, which in combination allow the coil to be tuned to the transmitter frequency thereby eliminating the wide energy wasting "wave problem" and allowing the energy used to focus in on a specific frequency increasing the range.
Beginning in the early 1960s resonant inductive wireless energy transfer was used successfully in implantable medical devices [14] 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 (>10kW) 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.
16-03-2011, 04:16 PM
Post: #10
RE: witricity full report

.doc  WITRICITY WIRELESS POWER TRANSMISSION.doc (Size: 438 KB / Downloads: 240)
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
18-03-2011, 11:40 AM
Post: #11
RE: witricity full report
Presented by:
RAVI KUMAR. A & RAMA CHANDRA. M


.ppt  WITRICITY.ppt (Size: 1.72 MB / Downloads: 398)
History of Wireless Power:
 In 1899, Sir Nikola Tesla Proposed a method of Wireless Power Transmission.
 As it is in Radiative mode, most of the Power was wasted and has less efficiency.
 The efficient midrange power transfer concept is Witricity. In this model source and load are in Magnetic resonance so there is no power loss.
Need of Witricity:
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.
Basic Principle:
The basic principle involved in Witricity concept is, Two objects having same resonating frequency and in Magnetic resonance at Strongly coupled regime tend to exchange energy , while dissipating relatively little energy to the extraneous off-resonant objects.
Experimental Design:
Our experimental scheme consists of two Self-resonant coils. One coil (source coil) is coupled inductively to an oscillating circuit; the other (device coil) is coupled inductively to a resistive load. Self-resonant coils rely on the interplay between distributed inductance and distributed capacitance to achieve resonance.
Range & Rate of Coupling:
Using Coupled Mode Theory (CMT), we can give some frame work to the system. The field system of the two resonant objects 1, 2 is
F(r,t)=a1(t)F1®+a2(t)F2®
Where F1,2® are the resonating modes of 1 and 2 alone, and then the field amplitudes a1(t) and a2(t).The lower order representation of the system is given by :
Where ω1, 2 are the individual frequencies, Γ1, 2 are the Resonance widths (Decay rates) due to the objects’ intrinsic (absorption, radiation etc.) losses, and ‘κ’ is the coupling coefficient .
 The solution of the equation show that at exact resonance at
ω1=ω2 and Γ1=Γ2
the normal modes of the combined system are split by 2κ.
 The energy exchange between the two objects takes place in time Pi/κ and is nearly perfect, apart for losses, which are minimal when the coupling rate is much faster than all loss rates (κ>> Γ1, 2).
 It is exactly this ratio {κ /sqrt (Γ1, 2)} shows that, it will set as figure-of-merit for any system under consideration for wireless energy-transfer, along with the distance over which this ratio can be achieved.
 The desired optimal regime {κ/sqrt (Γ1,2)>>1} is called “Strong-Coupling” regime. There is No change in Energy, unless κ/Γ>>1 is true.
Design of parameters:
The coupled mode theory plays a vital role in solving the lower order equations of the system. Using perturbation technique of
x(t)=A cos(ω 0t)+ B sin(ω 0t)
The solution of this equation is by including decay rate due to loss Γ0
X(t)=C exp(-i ω 0t)exp(-t/ Γ0)
Why the Perturbation technique??
All these fields are by Damped oscillator. The details of the damping mechanism is unknown to us, but the rate of energy loss due to damping known and it is small. So perturbation technique is the approach to solve these equations when the details is unknown to us. To solve the above equation considered a laser cavity and loss rates due to absorption and radiation is taken into account and finally found that κ/Γ ratio is proportional to the quality factor.
Formulation for Simulation:
Consider two loops at distance D between their centers, radius r1 and r2 of conducting wire with circular cross-section of radius ‘a’ and diameter ‘d’.via a dielectric of relative permittivity ε and everything surrounded by air.
To calculate the RLC parameters used the method called Finite-Element Frequency-Domain (FEFD) simulations (for Maxwell’s equations solving purpose) and Perturbation methods, we get the following formulae.
Simulation model Using COMSOL:
Simulation Performance:
à By the basic parameters, calculated results and performance given with and Without the External object in between the coils
Advantages:
☼ Unaffected by the day night cycle, weather or seasons.
☼ This is an eco friendly system..
☼ It is boon for the devices which uses midrange power
Limitations:
☼ The resonance condition should be satisfied and if any error exists, there is no possibility of power transfer.
☼ If there is any possibility of very strong ferromagnetic material presence causes low power transfer due to radiation.
29-03-2011, 10:59 AM
Post: #12
RE: witricity full report
Submiited By
A.Murali Krishna


.ppt  WiTricity.ppt (Size: 1.03 MB / Downloads: 218)
Introduction
Wireless+Electricity=WiTricity.

 Transmission of Electrical energy from one object to another object without use of wires is called WiTricity.
 Witricity is based on strong coupling between electromagnetic resonant objects to transfer energy wirelessly between them.
Past &Present
 Nikola Tesla(1856-1943) has done the Wireless power transmission experiments at Wardenclyffe
 In 18 99 he transmitted power wirelessly.
 High frequency current, of a Tesla coil, could light lamps filled with gas (like neon)
 The MIT researchers successfully demonstrated the ability to power a 60 watt light bulb wirelessly,
(Distance of 7 feet) under the guidance of Marin Soljacic.
 Working of Electric Tooth Brush
 Electric tooth brush contains 1 coil and a battery.
 One coil is in the charger .
Splashpower Recharging Mat
 Example For Resonance
 Copper coil
 Wireless power transfer
MIT EXPERIMENT
 two 5-turn copper coils of 60 cm (24 in) diameter,
 Distance Between The Coils :7 Feet(2 M)
 Load :60watt Bulb.
 Efficiancy:45%
 Resonant frequency : 9.9 MHz
 Transfer of energy from Moon to Earth
 Solar power from the satellite is sent to Earth using a microwave transmitter
 Received at a “rectenna” located on Earth
01-04-2011, 11:43 AM
Post: #13
RE: witricity full report
Presented by:
Shilpa gupta


.pptx  shilpa ppt.pptx (Size: 3.78 MB / Downloads: 239)
WITRICITY “The power without wires”
What is wpt?

Conventional energy transfer is done by using wires
The transmission of energy from one place to another without using wires.
Wireless power transfer is made possible by using various techniques
Why not wires?
Electrical energy transfer is through wires.
Most of energy loss is during transmission.
On an average, more than 30%.
In India it exceeds 40%.
Insulator cost is very high in wired transmission.
System becomes highly complex
Problem of power theft.
Why wpt?
Reliable
Efficient
Low maintenance cost
Fast
Can be used for short-range or long-range
TYPES AND TECHNOLOGIES OF W.P.T.
Microwave power transfer
Transfers high power from one place to another. Two places being in line of sight usually
Steps
Electrical energy to microwave energy
Capturing microwaves using rectenna
Microwave energy to electrical energy
5,000 MW Receiving Station (Rectenna), Snohomish, Washington. This station is about a mile and a half long
LASER transmission
LASER is highly directional, coherent
Not dispersed for very long
But, gets attenuated when it propagates through atmosphere
Simple receiver
Photovoltaic cell
Cost-efficient
Advantages of far- field energy transfer
Efficient
Easy
Need for grid, substations etc are reduced
Low maintenance
More effective when transmitting and receiving points are along a line of sight
Can reach the places which are remote
Disadvantages of far–field energy transfer
Radiative
Needs line of sight
Initial cost is high
When LASERs are used,
Conversion is inefficient
Absorption loss is high
When MICROWAVES are used,
Interference may arise
Fried bird effect
How safe is wpt?
Human beings or other objects placed between the transmitter and receiver do not hinder the power transmission
Magnetic fields tend to interact very weakly with the biological tissues of body, and so are not prone to cause any damage to any living beings
13-05-2011, 09:15 AM
Post: #14
RE: witricity full report

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.pptx  jyoti.pptx (Size: 1.39 MB / Downloads: 138)

.docx  final ABSTRACT.docx (Size: 81.03 KB / Downloads: 135)
1. INTRODUCTION
Can we imagine the life without electrical wires? From now answer to this question is Yes. The method proposed in the present paper called “WiTricity “will facilitate to Transfer power without using wires. (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.)
The efficient midrange power can be transmitted to any device which uses that range of power by the technique used in this WiTricity concept. Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all the above devices typically rely on chemical energy storage(Battery) .As they are becoming daily needs to present generation, Wireless energy transfer would be useful for many applications as above and they need midrange energy. This is the main reason to prepare this paper. When two Magnetically Resonating objects at “Strongly coupled” regime tend to exchange energy efficiently by transfer of power in the non-radiating fields. This is the basic principle involved in it. By taking two coils having same magnetic resonance and one is coupled to source and other is coupled to Device. So that the energy transfer is efficient even the air gap between them is high.
This paper describes the basic history of wireless power transmission, what are Magnetic resonance and strongly coupled regime, Experimental design, Range and rate of coupling (coupling calculations) and Design of parameters and Simulation for variation of power with and without the external object between source and load.
The technology used for wireless power transmission is known as WiTricity. Wireless power transmission is not a new idea; Nikola Tesla proposed theories of wireless power transmission in the late 1800s and early 1900s. Tesla's work was impressive, but it did not immediately lead to wide spread practical methods for wireless power transmission. Since then many 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. In 2006 researchers at Massachusetts Institute of Technology led by Marine Soijacic discovered an efficient way to transfer power between coils separated by a few meters. They have dubbed this technology as WiTricity.
WiTricity is based upon coupled resonant objects. Two resonant objects of the same resonant frequency tend to exchange energy efficiently, while not interchanging the surroundings. The researchers demonstrate the ability to transfer 60W with approximately 40% efficiency over distance in excess of 2 meters. Currently the project is looking for power transmission in the range of 100watts. As WiTricity is in the development stage, lots of work is to be done in improving the range of power transmission and efficiency. This chapter provides a literature review of the history of wireless power transfer throughout the last century. All of the methods that have been used to achieve wireless power transfer will be reviewed along with the advantages and disadvantages of each method. The chapter will conclude with a small discussion on issues with wireless power transfer.
2. What’s Happening Today!!!!!
Currently, wired electricity powers nearly everything. It travels through wires in the form of Alternating Current, and powers most of our devices in the form of Direct Current.
In our present electricity generation system we waste more than half of its resources. Especially the transmission and distribution losses are the main concern of the present power technology.
The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated. This loss implies that our present system of electrical distribution is only 70-74% efficient. We have to think of alternate technology to transmit and distribute the electricity. The transmission of power without wires may be one noble alternative for electricity transmission.
What do you mean by WiTricity!!!
The Transfer of Electricity from one place to another without wires is known as “WiTricity”.
On June 7 ’07, a team of researchers at MIT announced the successful operation of WiTricity concept.
They had lit up a 60W bulb with a power source at a distance of 7 feet(over 2m) with no wires.
Wireless transmission is useful in cases where instantaneous or continuous energy transfer is needed, without connecting wires.
Most common form of wireless power is carried out, using electrodynamic induction, microwaves or lasers
3. The Brain behind WiTricity
Prof. Marin Soljacic from Massachusetts Institute of Technology (MIT), is the one who has proved that magnetic coupled resonance can be utilized in order to transfer energy without wires. What's even more interesting is how he came about this idea. Soljacic, just like any of us was fed up of his 'low battery' beeping cell phone and wondered just like any of us if there was a way to get rid of this 'charging problem'.
However, here is where the difference between Soljacic and any of us comes in. He didn't just stand there wondering, instead he tried to figure out if there existed any physical phenomenon which could be of some help. He remembered Michael Faraday's discovery of electromagnetic induction (1831) and used it to come up with WiTricity
4. WiTricity Basics
There are 3 major types of wireless energy transfer:
Short range; Inductive Coupling
Medium range; Resonant Induction
Long range; Electromagnetic Wave Power Transfer
 Short Range Wireless Energy Transmission: Inductive Coupling
What Is Inductive Coupling?
Inductive Coupling is a method for short range wireless energy transfer.
Its range can vary, but it’s often very short.
Because of its short range it usually is used when the device containing the receiver and the device containing the transmitter are touching.
How does Inductive Coupling Work?
Inductive coupling works on the principles of electromagnetism:
When a current (electricity) passes through a wire, it generates a magnetic field perpendicular to the wire.
This effect can be magnified through coiling the wire.
When a wire is in proximity to a magnetic field, it generates a current in that wire.
Transferring energy between wires through magnetic fields is inductive coupling.
Magnetic fields decay quickly , making inductive coupling effective only at very short range
22-06-2011, 10:18 AM
Post: #15
RE: witricity full report
Presented by:
C.PAVANI


.doc  48257849-05091A0460-witricity.doc (Size: 360 KB / Downloads: 145)
ABSTRACT
The objective of this technical report is to provide electrical energy to remote objects without wires. Wireless energy transfer also known as wireless energy transmission is the process that takes place in any system where electromagnetic energy is transmitted from a power source to an electrical load, without interconnecting wires. Wireless transmission is employed in cases where interconnecting wires are inconvenient, hazardous, or impossible.
The principle of wireless electricity works on the principle of using coupled resonant objects for the transfer of electricity to objects without the use of any wires. A witricity system consists of a witricity transmitter and another device called the receiver.
The receiver works on the same principle as radio receivers where the device has to be in the range of the transmitter. It is with the help of resonant magnetic fields that witricity produces electricity, while reducing the wastage of power. The present report on witricity aims at power transmissions in the range of 100 watts. May be the products using WiTricity in future might be called Witric or Witric's.
CHAPTER 1
1.1 INTRODUCTION TO WITRICITY:

WITRICITY is a term which describes wireless energy transfer, the ability to provide electrical energy to remote objects without wires. Wireless energy transfer also known as wireless energy transmission is the process that takes place in any system where electromagnetic energy is transmitted from a power source (such as a Tesla coil) to an electrical load, without interconnecting wires. Wireless transmission is employed in cases where interconnecting wires are inconvenient, hazardous, or impossible. Though the physics can be similar (pending on the type of wave used), there is a distinction from electromagnetic transmission for the purpose of transferring information (radio), where the amount of power transmitted is only important when it affects the integrity of the signal.
Electricity is today a necessity of modern life. It is difficult to imagine passing a day without electricity. The conventional use of electricity is made possible through the use of wires.
The principle of wireless electricity works on the principle of using coupled resonant objects for the transfer of electricity to objects without the use of any wires. A witricity system consists of a witricity transmitter and another device called the receiver.
The receiver works on the same principle as radio receivers where the device has to be in the range of the transmitter. It is with the help of resonant magnetic fields that witricity produces electricity, while reducing the wastage of power. The present project on witricity aims at power transmissions in the range of 100 watts. May be the products using WiTricity in future might be called Witric or Witric's.
CHAPTER 2
2.1 WITRICITY TECHNOLOGY:

WiTricity power sources and capture devices are specially designed magnetic resonators that efficiently transfer power over large distances via the magnetic near-field. These proprietary source and device designs and the electronic systems that control them support efficient energy transfer over distances that are many times the size of the sources/devices themselves.
The WiTricity power source, left, is connected to AC power. The blue lines represent the magnetic near field induced by the power source. The yellow lines represent the flow of energy from the source to the WiTicity capture coil, which is shown powering a light bulb. Note that this diagram also shows how the magnetic field (blue lines) can wrap around a conductive obstacle between the power source and the capture device.
2.2 COUPLED RESONATORS:
To achieve wireless power transfer in a way that is practical and safe, one needs to use a physical phenomenon that enables the power source and the device (in this case, the mobile phone) to exchange energy strongly, while interacting only weakly with living beings and other environmental objects, like furniture and walls. The phenomenon of coupled resonators precisely fits this description. Two resonant objects of the same resonant frequency tend to exchange energy efficiently, while interacting weakly with extraneous off-resonant objects. A child on a swing is a good example of a resonant system. A swing exhibits a type of mechanical resonance, so only when the child pumps
her leg at the natural frequency of the swing is she able to impart substantial energy into the motion of the swing.
09-07-2011, 02:23 PM
Post: #16
RE: witricity full report

.docx  report.docx (Size: 1.9 MB / Downloads: 222)
Introduction
Now a days 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 Radioactive 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
What is WiTricity?
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. WiTricity technology is transferring electric energy or power over distance without wires. with the basics of electricity and magnetism, and work our way up to the WiTricity technology. Even better, because of WiTricity some of the devices won't enquire batteries to operate. No, this concept of wireless electricity is not new. 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. 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 hinders the transmission process), it is also very dangerous.
The Basics Of Witricity:-
Electricity: The flow of electrons (current) through a conductor (like a wire), or charges through the atmosphere (like lightning). A convenient way for energy to get from one place to another!
Magnetism: A fundamental force of nature, which causes certain types of materials to attract or repel each other. Permanent magnets, like the ones on your refrigerator and the earth’s magnetic field, are examples of objects having constant magnetic fields. Oscillating magnetic fields vary with time, and can be generated by alternating current (AC) flowing on a wire. The strength, direction, and extent of magnetic fields are often represented and visualized by drawings of the magnetic field lines.
Electromagnetism: A term for the interdependence of time-varying electric and
magnetic fields. For example, it turns out that an oscillating magnetic field produces
an electric field and an oscillating electric field produces a magnetic field.
Magnetic Induction: A loop or coil of conductive material like copper, carrying an
alternating current (AC), is a very efficient structure for generating or capturing a
magnetic field. If a conductive loop is connected to an AC power source, it will generate an oscillating magnetic field in the vicinity of the loop. A second conducting loop, brought close enough to the first, may “capture” some portion of that oscillating magnetic field,
which in turn, generates or induces an electric current in the second coil. The current
generated in the second coil may be used to power devices. This type of electrical power transfer from one loop or coil to another is well known and referred to as magnetic induction. Some common examples of devices based on magnetic induction are electric transformers and electric generators.
14-07-2011, 03:35 PM
Post: #17
RE: witricity full report

.doc  WITREPORT.doc (Size: 1.81 MB / Downloads: 171)
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.
27-12-2011, 10:40 AM
Post: #18
RE: witricity full report
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28-12-2011, 09:50 AM
Post: #19
RE: witricity full report
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20-01-2012, 10:31 AM
Post: #20
RE: witricity full report
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26-01-2012, 11:40 AM
Post: #21
RE: witricity full report
none of the ppts or doc or the replies .. suggests or explains how to setup a project with witricity principle !!!!
I need the requirements the procedure the circuit diagram all those things for my project
31-01-2012, 08:13 PM
Post: #22
RE: witricity full report
can u mail me the ful report to my mail id? please... my id is "shashikiran617[at]gmail.com"
01-02-2012, 10:57 AM
Post: #23
RE: witricity full report
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12-05-2012, 05:24 PM
Post: #24
RE: witricity full report
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15-05-2012, 10:14 AM
Post: #25
RE: witricity full report
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