SANTOSH KUMAR

ECE-IV B

--The Wireless Electricity.

By

1) History of Wireless power.

2) Need of Witricity.

3) Basic Principle.

4) Experimental Design.

5) Types of Wireless Transmission.

6) Applications.

7) Pros and Cons.

8) Conclusion.

History of Wireless Power: In 1899, 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.

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

Need of Witricity:Now a days there is a Rapid development of

autonomous electronics like Laptops, Cell-phones, House-hold robots and all those devices typically rely on chemical energy storage(Battery) As they are becoming daily needs to present generation, Wire less energy transfer would be useful for many applications as above and they need midrange energy.

Basic Principle:The basic principle involved in Witricity concept is,

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.

Experimental Design: Researchers used magnetic resonance coupling to power a 60-watt light bulb. Tuned to the same frequency, two 60-centimeter copper coils can transmit electricity over a distance of two meters, through the air and around an obstacle.

 

HOW WIRELESS POWER COULD WORK

1. Power from mains to antenna, which is made of copper

2. Antenna resonates at a frequency of 6.4MHz, emitting electromagnetic waves

3. 'Tails' of energy from antenna 'tunnel' up to 3 metres

4. Electricity picked up by laptop's antenna, which must also be resonating at 6.4MHz.

5. Energy used to re-charge device6. Energy not transferred to laptop re-absorbed by

source antenna. 7. People/other objects not affected as not

resonating at 6.4MHz.

TYPES OF WIRELESS TRANSMISSION Near field1.Induction2.Resonant inductionFar field1.Radio and microwave transmission2.Laser3.Electrical conduction

Near field:These are wireless transmission techniques over distances comparable to, or a few times the diameter of the device(s).

1.Induction: Inductive coupling -The action of an electrical

transformer is the simplest instance of wireless energy transfer. The primary and secondary circuits of a transformer are not directly connected. The transfer of energy takes place by electromagnetic coupling through a process known as mutual induction.

2.Resonant induction: By designing electromagnetic resonators that suffer

minimal loss due to radiation and absorption and have a near field with mid-range extent (namely a few times the resonator size), mid-range efficient wireless energy-transfer is possible.

RESONANT INDUCTION

According to the theory, one coil can recharge any device that is in range, as long as the coils have the same resonant frequency.

Witricity TodayMIT powered 60 watt light bulb from 2 meters (7 ft) at 40% efficiency

MIT researchers working on improving the technology

Limitations of mid-range power

100%Energy efficeincy

ExponentialDecay curve

d^x

TransmissionDistance d

Shortrange

Midrange

Low energy efficiency !

Coil radius 30cm, d = 2 meters , Efficiency 40%

The MIT team repeated TESLA”SExperiment in 2007

Witricity Tomorrow1) Power from mains to antenna, which is made of copper 2) Resonates 10MHz (electromagnetic waves)3) Tunnel up to 2m (6.5ft)4) Electricity received by antenna, also resonating at 10MHz. 5) Energy not transferred to laptop re-absorbed by source antenna. People/other objects not affected as not resonating at 10MHz

APPLICATIONS

Most electric toothbrushes rechargeThrough inductive coupling.

A Splashpower mat uses induction to recharge multiple devices simultaneously

Advantages:

☼ Unaffected by the day night cycle, weather or seasons.

☼ This is an eco friendly system..

☼ It is boon for the devices which uses midrange power.

☼ With the advent of wireless communication protocols such as Wi-Fi or Bluetooth, consumers are realizing that life without physical cables is easier, more flexible and often less costly.

☼Any low-power device, such as a cell phone, iPod, or laptop, could recharge automatically simply by coming within range of a wireless power source, eliminating the need for multiple cables—and perhaps eventually, for batteries.

china

india

nigeria

e-waste dumping aroung

Drastic reduction of electronic waste

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.

Witricity ConcernsWill it harm me?Will it harm the environment?Will it interfere with important

communication?

From these researches and discoveries it can be said that wireless power transmission is going to be a major field of interest for scientists and for people.

Tesla‟s resonance concept has made wireless power possible

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.