witricity wpt

WIRELESS POWER TRANSMISSION

By

Surya muttamsetty

Ravi kiran

AT A GLANCE

• What is wireless power transmission?

• History behind WPT

• Concept of electro magnetic induction and resonance

• Types of WPT’s

• whether it is virtual concept or existing

• Advantages and Disadvantages

• Applications and Conclusions

WHAT IS MEANT BY WPT?

• The transmission of energy from one place to another without using wires which is also known as “WiTricity”.

• Generally conventional energy is transferred using copper wires which results in large Copper loss.

• But now-a-days this wireless transmission is made possible in using various technologies based on Resonant frequency ,Inductive coupling etc.

WHAT IS THE NEED OF WPT?

• As per studies, most electrical energy transfer is through wires. • Most of the energy loss is during transmission as copper losses

• On an average, more than 30%

• In India, it exceeds 40%

Billions, trillions of $ is spend on wires and in their installation. Waste management a challenge in 21 century. 40 billion disposal batteries added to e-waste every year. PVC is non-biodegradable.

HISTORY

In 1891, 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.

• In 2005, Dave Gerding coined the term WiTricity which is being

used today.

• Forgotton invention was reborn in 2007

A BRIEF HISTORY OF NIKOLA TESLA EXPERIMENT!!!

• In 1891, Nikola Tesla invented a type of resonant transformer called the Tesla coil, which was used to generate very high voltage, low current, and high frequency alternating electricity. He experimented with a large variety of coils and configurations, one of which is as:

CONT…

• In1899,Tesla achieved a major breakthrough in his work at Colorado by transmitting 100 million volts of electric power wirelessly over a distance of 26 miles to light up a bank of 200 light bulbs and run one electric motor.

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.

BASIC PRINCIPLE USED IN WITRICITY

• RESONANCE INDUCTIVE COUPLING 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.

The equipment used is sometimes called a resonant or resonance transformer.

• 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.

DETAILED PRINCIPLE

BLOCK DIAGRAM OF WITRICITY

TYPES AND TECHNOLOGIES OF WPT

• Near-field techniques Inductive Coupling

Resonant Inductive Coupling

Air Ionization

• Far-field techniques Microwave Power Transmission (MPT)

LASER power transmission

ELECTRO MAGNETIC INDUCTIVE COUPLING

It is based on the FARADAY’S LAW OF ELECTROMAGNETIC INDUCTION

Make use of coils. The coils are not connected through wire or any other kind of material.

Transfer of energy is due to mutual induction.

Its based on the concept :- that an oscillating electric field produces magnetic field and an oscillating magnetic field produces oscillating electric field

RESONANT INDUCTIVE COUPLING

Same inductive coupling(EMI) concept but the coils here operate at their resonating frequency.

Inductance induces current.

Resonance makes both the coil to operate at same frequency.

Fields are non-radiative in nature.

RIC VS INDUCTIVE COUPLING

RIC is highly efficientRIC has much greater range than inductive couplingRIC is directional when compared to inductive couplingRIC can be one-to-many. but usually inductive coupling is one-to-oneDevices using RIC technique are highly portable

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

ADVANTAGES OF NEAR FIELD TECHNOLOGY

For short range transmission Aims low power transmission Need for battery is eliminated Efficient energy transfer using RIC Harmless, if field strengths under safety levels Maintenance cost is less

DISADVANTAGES OF NEAR FIELD TECHNOLOGY

Distance constraint Field strengths have to be under safety levels Initial cost is high In RIC, tuning is difficult High frequency signals must be the supply

APPLICATION OF NEAR FIELD TECHNNOLOGY

Electric automobile charging Consumer electronics Industrial purposes Sharing information

FAR FIELD ENERGY TRANSMISSION TECHNIQUES

Microwave Power Transmission (MPT) LASER Power Transmission Solar power Satellite(SPS)

FAR FIELD ENERGY TRANSMISSION

Aims high power transmission For long range of transmission Require line of sight Radiative in nature

MICROWAVE POWER TRANSMISSION (MPT)

Transfers high power from one place to another. Two places being in line of sight usually.Electrical energy converted to microwave energy

using magnetron.Capturing microwave using retina.Conversion of microwave energy into electrical

energy.Transmission of electrical energy.

LASER POWER TRANSMISSION

LASER is highly directional and coherentBut, gets attenuated when it propagates

through atmosphere Simple receiver

• Photovoltaic cellCost-efficient

SOLAR POWER SATELLITE(SPS)

Satellites are placed in geostationary orbit Solar energy is captured using photocells Each SPS may have 400 million photocells Transmitted to earth in the form of

microwaves/LASER Using rectenna/photovoltaic cell, the energy

is converted to electrical energy Efficiency exceeds 95% if microwave is used.

ADVANTAGE OF FAR FIELD TECHNIQUE

Efficient,Easy Need for grids, substations etc are eliminated More effective when the transmitting and receiving points are along a line-of-

sight

ADVANTAGES & DISADVANTAGES OF FAR FIELD TECHNIQUE

Advantages

Efficient, Easy Need for grids, substations etc are

eliminated More effective when the

transmitting and receiving points are along a line-of-sight

Disadvantages

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

Needs positioning and GPS systems.

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.

• Direct Wireless Power• No device needs wires

• Immobile devices

• Automatic Wireless Charging• Device with rechargeable batteries

• charges itself

• Mobile device

• Used in and out of range of its WiTricity power source

WITRICITY APPLICATIONS

• Consumer Electronics

• Industrial

• Transportation

• Miscellaneous

SOME MORE APPLICATIONS…….

• Safe, fairly efficient, good range:• Magnetic fields interact weakly with biological

masses (humans),• 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.

ADVANTAGES:

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.

LIMITATIONS

• MIT's WiTricity is only 40 to 45% efficient and they have to be twice as efficient to compete with the traditional chemical batteries.

• Aim is to get a robotic vacuum or a laptop working, charging devices placed anywhere in the room

• The researchers have said that in another five years time, they will come up with a WiTricity system for commercial use.

WHAT'S THE FUTURE OF WITRICITY?

MAY BE IN FUTURE

1. An article published in the Science Magazine as “Wireless Power Transfer via Strongly Coupled Magnetic Resonances” by Andre kurs, Science 317, 83(2007); Dol:10.1126/ science.1143254.

2. H. Haus , “Waves and Fields in Optoelectronics”, Prentice hall Publishers, Englewood

3. http://electron9.phys.utk.edu/optics507/modules/m6/coupled_resonators.htm

4. “Efficient Non-Radiative Midrange Energy Transfer” by Aristeidies karalis, Marlin Soljacic.

5. Nikola Tesla, My Inventions, Ben Johnston, Ed., Austin, Hart Brothers, p. 91,1982.

6. Thomas F. Valone, “ Tesla’ s Wireless Energy... For the 21st Century!!! One Step Beyond Direct TV!!!” Extra Ordinary Technology, 1, no. 4, Oct / Nov / Dec 2003.

7. James O. McSpadden, “ Wireless Power Transmission Demonstration”, Texas A&M University, June, 1997.

8. Charych Arthur (Setauket, NY), “ System and method for wireless electrical power transmission”, Patent No. 6,798,716, September 28, 2004.

9. Joe T. Howell, et. al , “Advanced receiver / converter experiments for laser wireless power transmission”5th. Wireless transmission conference, pp 1-8, Garanda, Spain,2004.

BIBLIOGRAPHY