Witricity by Shashank

WITRICTY

NAME: SHASHANK H

USN NO: 1RE11EE099

GUIDE: DR. B.P. DIVAKAR

REVA INSTITUTE OF TECHNOLOGY AND MANAGEMENT, BANGALORE-560064

Electrical and Electronics Engineering Department

CONTENTS Introduction

History of Witricity

First Experiment on Witricity

Working of Witricity

Advantages & Disadvantages

Safety concerns

Application

Design

References



INTRODUCTION• Process of transferring electric energy or power over distance without wires

through the air.

• Eliminates the use of cables for transmission of power.

• Known as “WiTricity” and “ Wireless Power Transmission”.

• The term WiTricity was used for a project that took place at MIT, led by Marin Soljačić in 2007.

• A Witricity system consists of a Witricity transmitter and the receiver which works on the principle of Radio Receivers.

• Witricity uses resonant magnetic field while reducing the wastage of power.



HISTORY OF WITRICITY• In 1899,Sir Nikola Tesla proposed a method of Wireless

Power Transmission.

• Enlighten 200 lamps at the distance of 40 km. But only 15% efficiency was achieved.

• As it is in Radiative mode , most of the Power was wasted and had less efficiency.

• Wardenclyffe Tower built on Long Island, NY in 1904.

• Tesla’s vision to transmit power and information.

• Destroyed in 1917.



FIRST EXPERIMENT ON WITRICITY• A group of engineers at MIT came up with the idea

to use resonant induction to transmit power wirelessly.

• MIT powered 60 watt light bulb from 2 mts (7 ft) at 40% efficiency.

• One coil (source coil) is coupled inductively to an oscillating circuit; the other (device coil) is coupled inductively to a resistive load.

• The interplay between distributed inductance and distributed capacitance achieves resonance.



WORKING OF WITRICITY• Magnetic coil is housed in a box and

can be set in wall or ceiling.

• Antenna A resonates at a specific frequency.

• Electromagnetic waves transmitted through the air.

• Second magnetic coil (Antenna B) resonates at same frequency as first coil and absorbs energy.



BLOCK DIAGRAM REPRESENTATION



ADVANTAGES• No need of power cables and batteries.

• Does not interfere with radio waves.

• Wastage of power is small.

• Negative health implications.

• Highly efficient than electromagnetic induction

• Less costly.



DISADVANTAGES

• Wireless power transmission can be possible only in few metres.

• Over-heating occurs because of different voltages.

• Refitting old equipment or purchasing new equipment.

• Energy Theft.



SAFETY CONCERNS• Shock prevention.

• Magnetic fields do not cause any damage to any living beings.

• May increase a person’s body temperature or may heat body tissues and may stimulate nerve and muscle tissues



APPLICATIONS• Consumer Electronics

Automatic wireless charging of mobile electronics (phones, laptops, game controllers, etc.)in home, car, office.

• Industrial

Direct wireless power and communication interconnections at points of use in harsh environments(drilling, mining, underwater, etc.)

• Transportation

Automatic wireless charging for existing electric vehicles: golf carts, industrial vehicles.





In the Future

DESIGNDesign Aspects: Design of coil

• The LC circuit must be driven, for example by an AC power supply, for resonance to occur. The frequency at which this equality holds for the particular circuit is called the resonant frequency.

• In order to achieve a resonance frequency in the oscillator circuit the inductive reactance and the capacitive reactance of the resonator coil will equal such that:

XL= XC (1)

Where ωL = 1÷ ωC And

ω = 2×π×f



DESIGN CONTINUED• Capacitive Reactance: XC = 1÷ 2fC (2)

• Inductive Reactance: XL = 2fL (3)

• Resonant Circuit formula: 4π2f2LC = 1 (4) Where f= 1÷2 π(LC) ½ (5) XC = Capacitive Reactance in ohms XL = Inductive Reactance in ohms

f= Frequency in hertz L = Inductance in Henry C = Capacitance in farads



REFERENCES• Hirai, J., Kim, T.-W. and Kawamura, A. “Wireless transmission of power and

information and information for cableless linear motor drive.” IEEE Trans. on power electronics 15, 21 (2000).

• Esser, A. and Skudelny, H.-C. “A new approach to power supplies for robots.” IEEE Trans. on industry applications 27, 872 (1991).

• Ka-Lai, L., Hay, J. W. and Beart, P. G. W. “Contact-less power transfer.” U.S. patent number 7,042,196, issued in May 2006. (SplashPower Ltd., www.splashpower.com)

• Fernandez, J. M. and Borras, J. A. “Contactless battery charger with wireless control link.” U.S. patent number 6,184,651, issued in February 2001.

• www.witricity.com



THANK YOU

