ELECTRICITY THROUGH WIRELESS TRANSMISSION-WITRICITY

by

AMBER BHAUMIKPG-DESD

Introduction

In our present electricity generation system we waste more than half of its resources. Especially transmission and distribution losses are main concern of the present power technology.

The transmission and distribution system causes a loss of 26% to 30% of energy generated.

The transmission of power without wires is one of the alternative for electricity transmission

History of Wireless Power

In 1899, Sir Nikola Tesla Proposed a method of Wireless Power Transmission.

The efficient midrange power transfer concept is Witricity. In this model source and load are in Magnetic resonance so there is no power loss.

Nikola Tesla – The GeniusHe enlighted 200 lamps at the distance of 40 km, Wirelessly !

What is WiTricity ?

definition is : * “Transmission of energy through the air”.* A system of two electromagnetic resonators coupled mostly through their magnetic fields.

* Cables are going to replaced by WiTricity.

* Efficient power transfer

Need of Witricity:

* Cell phones, i pods, laptop computers are capable of re-charging themselves without ever being plugged in.

The forgotten invention is reborn in 2007RESONANCE COUPLING

A group of engineers at MIT came up with the idea to use resonant induction to transmit power wirelessly.

“Resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied.

Research at MIT

* Prof. Soljacic – Another GeniusMIT-IBM Collaboration

* He did succeed to redesign Tesla’s experiment in safer way.* They had lit up a 60W bulb with a power source at a distance of 7 feet(over 2m) with no wires

Experiment demonstrated at MIT.A 60W light bulb lit from source at a distance of 2m from load.

Electric bulb lightened even when a barrier was kept in between.

Types and Technologies

Near-field techniques Inductive Coupling Resonant Inductive Coupling Air Ionization

Far-field techniques Microwave Power Transmission (MPT) LASER power transmission

Inductive coupling

Primary and secondary coils are not connected with wires.

Energy transfer is due to Mutual Induction

Cont…

Energy transfer devices are usually air-cored

Transformer is an example Wireless Charging Pad(WCP),electric

brushes are some examples Nokia Lumia 720 The charging pad (primary coil) and the

device(secondary coil) have to be kept very near to each other

RESONANT INDUCTIVE COUPLING

The capacitor and inductor forms the resonator. Charge oscillates between inductor (as magnetic field) and capacitor (as electric field.)

This type of oscillation is called resonance if the reactance's of the inductor and capacitor are equal.

RESONANT INDUCTIVE COUPLING

Resonant transfer works by making a coil ring with an oscillating current.

This generates an oscillating magnetic field. Because the coil is highly resonant any energy

placed in the coil dies away relatively slowly over very many cycles.

But if a second coil is brought near it, the coil can pick up most of the energy before it is lost, even if it is some distance away.

BLOCK DIAGRAM

BLOCK DIAGRAM

Oscillator used is an astable multivibrator using 555timer which switches IRFP250 to produce oscillations in the primary coil.

Secondary coil kept at a distance resonates at the same frequency and power transfer takes place.

Signal received in the secondary is rectified and regulated.

Resonant Inductive Coupling

RESONANT INDUCTIVE COUPLING

Inductive charging uses an electromagnetic field to transfer energy between two objects.

Greater distances can be achieved by using resonant inductive coupling.

Resonant inductive coupling or electrodynamic induction is the near field wireless transmission between two coils that are tuned to resonate at the same frequency.

Air Ionization

Toughest technique under near-field energy transfer techniques

Air ionizes only when there is a high field Needed field is 2.11MV/m Natural example: Lightening Not feasible for practical implementation.

Far-field energy transfer

Microwave Power Transfer(MPT) Transfers high power from one place to another. Steps:

Electrical energy to microwave energy Capturing microwaves using rectenna Microwave energy to electrical energy

AC can not be directly converted to microwave energy

AC is converted to DC first DC is converted to microwaves using magnetron Transmitted waves are received at rectenna which

rectifies, gives DC as the output DC is converted back to AC

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

Applications

Direct Wireless Power No device needs wires For TVs, toasters or any form of

Immobile devices

Automatic Wireless Charging Device with rechargeable

batteries charges itself

For any form of mobile device

Some more Applications…

*Industrial

would be free of heavy installation of wires and devoid of any hazardous electric shock incidents.

*Transportation Could charge an electric car or automobile.

Wireless power transmission is safe

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

Efficient and reliable power.

Provides solution to the ever increasing demand for power.

A solution to reduce e-waste- a more safe environment.

A more cost effective methodology for getting electricity to your houses which includes paying less for use of power.

Disadvantages.

For short and mid range transfer system has to be set at the right frequency or there would be no power transfer.

For long range the installation cost is high.

CONCLUSION

Transmission without wires- a reality Efficient Low maintenance cost. But, high

initial cost Better than conventional wired

transfer Energy crisis can be decreased Low loss In near future, world will be

completely wireless

Thank you