Wireless Electricity Transmission Presented By Ashutosh Trivedi (0704320011)

outline WiTricity HOW WIRLESS POWER COULD WORK How Safe is WiTricity? MIT's Experiment: The Future of WiTricity. METHODS USED FOR WIRELESS POWER TRANSMISSION ADVANTAGES OF WITRICITY DISADVANTAGES APPLICATIONS Conclusions

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 cellphones, 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.

HOW WIRLESS POWER COULD WORK: WiTricity - Wireless Electricity, these words are simpler said than done. The concept behind this fascinating term is a little complex. However, if you want to understand it, try and picture what I state in the next few lines. Consider two self resonating copper coils of same resonating frequency with a diameter 20 inches each. One copper wire is connected to the power source (WiTricity transmitter), while the other copper wire is connected to the device (WiTricity Receiver). The electric power from the power source causes the copper coil connected to it to start oscillating at a particular (MHz) frequency. Subsequently, the space around the copper coil gets filled with nonmagnetic radiations. This generated magnetic field further transfers the power to the other copper coil connected to the receiver. Since this coil is also of the same frequency, it starts oscillating at the same frequency as the first coil. This is known as 'coupled resonance' and is the principle behind WiTricity

How Safe is WiTricity? Human beings or other objects placed between the transmitter and receiver do not hinder the transmission of power. However, does magnetic coupling or resonance coupling have any harmful effects on humans? MIT's researchers are quite confident that WiTricity's 'coupling resonance' is safe for humans. They say that the magnetic fields tend to interact very weakly with the biological tissues of the body, and so are not prone to cause any damage to any living beings.

MIT's Experiment: In 2007, Marin Soljacic led a five member team of researchers at MIT (funded by Army Research Office, National Science Foundation and the Department of Energy) and experimentally demonstrated transfer of electricity without the use of wires. These researchers were able to light a 60W bulb from a source placed seven feet away, with absolutely no physical contact between the bulb and the power source. The first copper coil (24 inches in diameter) was connected to the power source and the second was connected to the bulb, and were made to resonate at a frequency of 10 MHz. The bulb glowed even when different objects (like a wooden panel) were placed between the two coils. The system worked with 40% efficiency and the power that wasn't utilized remained in the vicinity of the transmitter itself, and did not radiate to the surrounding environment

The Future of WiTricity. MIT's WiTricity is only 40 to 45% efficient and according to Soljacic, they have to be twice as efficient to compete with the traditional chemical batteries. The team's next aim is to get a robotic vacuum or a laptop working, charging devices placed anywhere in the room and even robots on factory floors. The researchers are also currently working on the health issues related to this concept and have said that in another three to five years time, they will come up with a WiTricity system for commercial use. WiTricity, if successful will definitely change the way we live. Imagine cellphones, laptops, digital camera's getting self charged! Wow! Let's hope the researchers will be able to come up with the commercial system soon. Till then, we wait in anticipation!

WiTricity, if successful will definitely change the way we live WiTricity, if successful will definitely change the way we live. Imagine cellphones, laptops, digital camera's getting self charged!

METHODS USED FOR WIRELESS POWER TRANSMISSION 1. INDUCTION (INDUCTIVE COUPLING) 2.RESONANT INDUCTION (EVANESCENT WAVE COUPLING

1 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 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 low distance, but this process is extremely inefficient. Since magnetic field spreads in all direction, making a large wastage of energy.

RESONANT INDUCTION 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 plate. Unlike multiple layer secondry 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.

ADVANTAGES OF WITRICITY 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 riot propagate through air to be absorbed or dissipated. So the wastage is small. 5. Negative health 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 inductionsystem is one million times as efficient as electro magnetic induction system. 7.Less costly - The components of transmitter and receivers arecheaper. So this system is less costly

DISADVANAGES 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 andefficient.

Conclusions  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

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