“Wireless Electricity” WiTricity “Wireless Electricity” PRESENTED BY MRUDUL SHYAM

CONTENTS What do you mean by WiTricity? Need of WiTricity History of wireless power WiTricity Basics

WHAT DO YOU MEAN BY “WiTricity”???? The Transfer of Electricity from one place to another without wires is known as “WiTricity”. On June 7,2007 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.

HISTORY OF WIRELESS POWER As it is in radiative mode, most of the power was wasted and has less efficiency In 1891, Sir Nikola Tesla Proposed a method of Wireless Power Transmission.

LIMITATION OF TESLA’S COIL A Tesla Coil produces high voltage electric arcs. These arcs cause permanent damage to electrical devices on contact Tesla coils also destroy hearing aids and cardiac pacemakers in their vicinity.

What’s Happening Today?????? Currently, wired electricity powers have concurred nearly everything. In the 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.

Cont…. The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated The transmission of power without wires may be one noble alternative for electricity transmission.

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. He used Michael Faraday's principle of electromagnetic induction (1831) came up with WiTricity.

“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 Inductive Coupling is a method for short range wireless energy transfer. Its range can vary, but it’s often very short.

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. When a wire is in proximity to a magnetic field, it generates a current in that wire. Magnetic fields decay quickly , making inductive coupling effective only at very short ranges.

MEDIUM RANGE WIRELESS ENERGY TRANSMISSION: RESONANT INDUCTION What is “Resonant Induction”? A group of engineers at MIT came up with the idea to use resonant induction to transmit power wirelessly. They deemed their result “WiTricity” (like Wi-Fi) . WiTricity can transmit electricity wirelessly at 40% efficiency to about 7 feet.

Cont… Group of engineers at MIT

HOW DOES RESONANT INDUCTION WORK? Resonant induction still uses the same principles as magnetic induction (magnetic fields to transfer current) , but it uses resonance to increase the range at which the transfer can efficiently take place. “Resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied.

Cont……..

Cont…. Everything resonates at a certain frequency, based on its shape and material. With resonant induction, power is transmitted between two resonating coils.

Detailed Principle 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 , while the other copper wire is connected to the device.

MECHANISM

DEMO 1 One source is able to transfer the energy for the electronic devices.

DEMO 2 Sony demonstrated its wirelessly powered television [2010 October]

Demonstration of WiTricity on cellphone and LCD at the TED conference.

DEMO 3 Batteries can be charged , it is just enough to place the device to top of one of these surfaces.

DEMO 4 Charging Electric Car using WiTricity.

HOW SAFE IS WiTricity? Human beings or other objects placed between the transmitter and receiver do not hinder the transmission of power. 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.

ADVANTAGES: Safe, fairly efficient, good range. Efficiency can be increased with time, most of the 60% lost is from heat radiated from the coils. 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.

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.

FUTURE OF “WiTricity” Think that the city will be covered with WiTricity hot spots, just like Wireless Internet, there will be no need of charging batteries, or carrying adapters all around !