Witricity report

WITRICITY

A Seminar Report

Submitted ByGARIMA ARYA

(BTBTL13543)

In partial fulfillment for the award of the degree of

Bachelor in technologyIn

Electrical and Electronic Engineering

Department of Electronics

Banasthali Vidyapith

Rajasthan-304022(India)

2015

BANASTHALI VIDYAPITHDEPARTMENT OF ELECTRONICS[Type text]

ACKNOWLEDGEMENT

I am highly indebted to Dr. Ritu Vijay, HOD of Electronics Department, for her supervision as well as for providing necessary information regarding the report& also for her support in completing the seminar work.I would like to express my deep and sincere gratitude to my coordinator Mr. Pawan Pathak, of Electrical and Electronics Engineering for his unflagging support and continuous encouragement throughout the seminar work. Without his guidance and persistent help this report would not have been possible.

I must acknowledge the faculties and staffs of Electronics Department of Banasthali Vidyapith, who gave the permission to use all required material to complete the seminar work and the report.

It’s my great pleasure to acknowledge my classmates for giving me appreciable suggestions for my seminar topic and helping me in solving problems that occurred while making this report. Their support made it possible for me to complete this report.

GARIMA ARYADepartment of Electrical and Electronics Engineering(BTBTL13543)


DECLARATION

I hereby declare that this submission is my own work and that, to the best of my knowledge and belief, it contains no matter previously published or written by another person nor material which to a substantial extent has been accepted for the award of any other degree or diploma of the university or another institute of higher learning, except where due acknowledgement has been made in the text.

SignatureGarima Arya

ID-BTBTL13543


TABLE OF CONTENT

Abstract Introduction Need Of WiTricity History Basic Principle Types Of Coupling Of Coils Advantage and Disadvantages Applications Future Scope Conclusion References


ABSTRACT

Can we imagine the life without electrical wires? From now answer to this question is yes. The method proposed in the present paper called “Witricity” will facilitate to Transfer power without using wires. The efficient midrange power can be transmitted to any device which uses that range of power by the technique used in this Witricity concept. Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all the above devices typically rely on chemical energy storage(Battery) .As they are becoming daily needs to present generation, Wireless energy transfer would be useful for many applications as above and they need midrange energy. This is the main reason to prepare this paper. Wireless electricity or witricity is the transfer of electric energy or power over a distance without the use of wires. In order for the energy to be transferred safely coupled resonators are used. When two magnetically resonating objects at “Strongly coupled” regime tend to exchange energy efficiently by transfer of power in the non-radiating fields. This is the basic principle involved in it. By taking two coils having same magnetic resonance and one is coupled to source and other is coupled to Device. So that the energy transfer is efficient even the air gap between them is high. This paper describes the basic history of wireless power transmission, what are Magnetic resonance and strongly coupled regime, Experimental design, Range and rate of coupling (coupling calculations) and Design of parameters and Simulation for variation of power with and without the external object between source and load. Using witricity there would be no need to replace batteries because energy could be transferred from one sensor to another.

These witricity applications are expected to work on the gadgets that are in close proximity to a source of wireless power wherein the gadget charges automatically without necessarily having to get plugged in. There are no limitations in witricity power applications where anything and everything that used to run with batteries or electrical connections can be used using witricity.

Just imagine, the future witricity power applications permit you to use wireless energy, without having to replace or recharge batteries. There will be no need of getting rid of these batteries either or of remembering to recharge batteries periodically. In addition to this, with witricity, there is no need of plugging in any wires and plugs and thus face a mess of wires.


INTRODUCTION

Our forefathers marveled at the invention of Thomas Edison's glowing light bulbs (1879), however, to us 21st centurions, the light bulb is nothing out of the ordinary. When computers, cell phones, laptops, iPods, etc., were invented our antennas tweaked. Now, this is what you call invention! However, as time progresses we get used to these devices, and they seem to be less fascinating. In fact, charging all these appliances has become so very cumbersome.

Each appliance has its own set of chargers, and with every family member owning their cell phones, the drawers are overflowing with all sorts of wires. How many times have you wished if there was a way to do away with all the wiry clutter? When you're on your way to work and your cell phone beeps in hunger for a battery charge, haven't you wished your cell phone battery could get 'self charged'. Well your plight has been heard by doctor 'WiTricity'.

WiTricity is nothing but wireless electricity. Transmission of electrical energy from one object to another without the use of wires is called WiTricity. It will ensure that the cell phones, laptops, iPods, and other power hungry devices get charged on their own, eliminating the need for plugging them in. Even better, because of WiTricity some of the devices won't require batteries to operate.

Much of this power is wasted during transmission from power plant generators to the consumer. The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated. This loss implies that our present system of electrical distribution is only 70-74% efficient. We have to think of alternate state - of - art technology to transmit and distribute the electricity. Now- a- days global scenario has been changed a lot and there are tremendous development in every field. If we don’t keep pace with the development of new power technology we have to face a decreasing trend in the development of power sector. The transmission of power without wires may be one noble alternative for electricity transmission.Now a days there is a Rapid development of autonomous electronics like Laptops, Cell-phones, House-hold robots and all Batteries .As they are becoming daily needs to present generation, Wireless energy transfer would be useful for many applications as above and they need midrange energy. This is the main reason to prepare this paper. When two Magnetically Resonating objects at “Strongly coupled” regime tend to exchange energy efficiently by transfer of power in the non-radiating fields. This is the basic principle involved in it. By taking two coils having same magnetic resonance and one is coupled to source and other is coupled to Device. So that the energy transfer is efficient even the air gap between them is high.


NEED OF WITRICITY

Now a days there is a Rapid development of autonomous electronics like laptops, cell-phones,

house-hold robots and all the above devices typically rely on chemical energy

storage(Battery) .As they are becoming daily needs to present generation, Wireless energy

transfer would be useful for many applications as above and they need midrange energy.

Currently, wired electricity powers nearly everything. It travels through wires in the form of

Alternating Current, and powers most of our devices in the form of Direct Current. In our 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.

The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30%

of the energy generated. This loss implies that our present system of electrical distribution is only

70-74% efficient. We have to think of alternate technology to transmit and distribute

the electricity. The transmission of power without wires may be one noble alternative for

electricity transmission.

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.

What's even more interesting is how he came about this idea. Soljacic, just like any of us was fed

up of his 'low battery' beeping cell phone and wondered just like any of us if there was a way to

get rid of this 'charging problem'.


HISTORY

Wireless power transmission is not a new idea; Nikola Tesla proposed theories of wireless power transmission in the late 1800s and early 1900s. Tesla's work was impressive, but it did not immediately lead to wide spread practical methods for wireless power transmission. Since then many researchers have developed several techniques for moving electricity over long distances without wires. Some exist only as theories or prototypes, but others are already in use.

Fig.Nikola Tesla and his experimented tower

William C Brown demonstrated a micro wave powered model helicopter in 1964. This receives all the power needed for flight from a micro wave beam. In 1975 Bill Brown transmitted 30kW power over a distance of 1 mile at 84% efficiency without using cables.

In 2007, Marin Soljacic led a five member team of researchers at MIT (funded by Army Research Office, National Science Foundation and the Department of Energy) and experimentally demonstrated transfer of electricity without the use of wires. These researchers were able to light a 60 W bulb from a source placed seven feet away, with absolutely no physical contact between them.


Fig.MIT inventers of WiTricity

The first copper coil (24 inches in diameter) was connected to the power source and the second was connected to the bulb, and were made to resonate at a frequency of 10 MHz. The bulb glowed even when different objects (like a wooden panel, etc.,) were placed between the two coils. The system worked with 40% efficiency and the power that wasn't utilized remained in the vicinity of the transmitter itself, and did not radiate to the surrounding environment.

Fig.Exprimental arrangement


BASIC PRINCIPLE

WiTricity―Wireless Electricity, these words are simpler said than done. The concept behind this fascinating term is a little complex. However, if you want to understand it, try and picture what I state in the next few lines.

Consider two self-resonating copper coils of the same resonating frequency with a diameter of 20 inches each. One copper wire is connected to the power source (WiTricity transmitter), while the other is connected to the device (WiTricity Receiver).

The electric power from the power source causes the copper coil connected to it to start oscillating at a particular (MHz) frequency. Subsequently, the space around the copper coil gets filled with non-magnetic radiations. This generated magnetic field further transfers the power to the other copper coil connected to the receiver. Since this coil is also of the same frequency, it starts oscillating at the same frequency as the first coil. This is known as 'coupled resonance' and is the principle behind WiTricity.

Fig.Basic principle diagram


TYPES OF COUPLING OF COILS

a) Inductive Coupling: Inductive coupling is the action of 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. The receiver must be very close to the transmitter or induction unit in order to inductively couple with it.

Fig.Inductive coupling

b) Resonance Coupling: The idea of such mid-range induction was given by Marin Soljacic for efficient wireless transfer. The reason behind it is that, if two such resonant objects are brought in mid-range proximity, their near fields (consisting of so-called 'evanescent waves') and can allow the energy to transfer from one object to the other within times much shorter than all loss times, which were designed to be long, and thus with the maximum possible energy-transfer efficiency. Electromagnetic resonance induction works on theprinciple of a primary coil generating a predominantly magnetic field and a secondary coil being within that field so a current is induced within its coils, when both of these are made to resonate at same frequency they become much efficient.


Fig.Resonant coupling

c)Laser/Microwave Transmission: Such power transmissions can be made effective at long range power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A rectenna may be used to convert the microwave energy back into electricity. These provide 95% efficiency. A new company, Powercast introduced wireless power transfer technology using RF energy this system is applicable for a number of devices with low power requirements. Currently, it achieves a maximum output of 6 volts for a little over one meter.

Fig. 4. Example of European Space Agency Aeolus Satellite with laser beam pointing at the Earth's atmosphere.

Energy Transmission via laser is an efficient way for long range, except for it requires a proper line of sight for power beaming. In the case of light, power can be transmitted by converting electricity into a laser beam that is then fired at a solar cell receiver. With such laser beam efficiencies it is planned to build a solar panel grid in space & transferring the solar energy to earth receivers via laser methods.


ADVANTAGES

No need of line of sight - In witricity power transmission there is any; need of line of sight between transmitter and receiver. That is power! Transmission can be possible if there are any obstructions like wood, metal, or other devices were placed in between the transmitter and receiver.

No need of power cables and batteries - Witricity replaces the use of power cables and batteries.

Does not interfere with radio waves. Wastage of power is small - Electromagnetic waves would tunnel, they would not

propagate through air to be absorbed or dissipated. So the wastage is small. Highly efficient than electromagnetic induction - Electromagnetic induction system can

be used for wireless energy transfer only if the primary and secondary are in very close proximity. Resonant induction system is one million times as efficient as electromagnetic induction system.

Less costly - The components of transmitter and receivers are cheaper. So this system is less costly.

DISADVANTAGES

A number of companies and academic institutions (including Intel and MIT) are involved in a race to be the first to release marketable wireless energy packages; however, there are a number of limitations to the full implementation of wireless energy transfer:

Size: The copper rings which create resonance and energy are simply too big for them to be part of any wireless energy package.

Range: The range of wireless energy transfer is just a few meters, which is a major hurdle. Efficiency: Wireless energy transfer ensures between 45% and 80% of the energy put in is transferred, which is much less efficient than regular wired connections.

Cost: The cost of developing and implementing wireless energy networks means that it would be too expensive for the end-user to afford at this point.


APPLICATIONS

WiTricity -wireless power transfer technology can be applied in a wide variety of applications and environments. The ability of our technology to transfer power safely, efficiently, and over distance can improve products by making them more convenient, reliable, and environmentally friendly. WiTricity technology can be used to provide:

1) Automatic Wireless Power Charging: When all the power a device needs is provided wirelessly, and no batteries are required. This mode is for a device that is always used within range of its WiTricity power source. When a device with rechargeable batteries charges itself while still in use or at rest, without requiring a power cord or battery replacement. This mode is for a mobile device that may be used both in and out of range of its WiTricity power source.

Fig. Automatic Wireless Power Charging.

2) Consumer Electronics :

a) Automatic wireless charging of mobile electronics (phones, laptops, game controllers, etc.) in home, car, office, Wi-Fi hotspots while devices are in use and mobile.

b) Direct wireless powering of stationary devices (flat screen TV‘s, digital picture frames, home theatre accessories, wireless loud speakers, etc.) eliminating expensive custom wiring, unsightly cables and wall-wart power supplies.

c) Direct wireless powering of desktop PC peripherals: wireless mouse, keyboard, printer, speakers, display, etc. eliminating disposable batteries and awkward cabling.


Fig. Automatic Wireless charging of Mobile electronics.

3) Industrial :

a) Direct wireless power and communication interconnections across rotating and moving joints (robots, packaging machinery, assembly machinery, machine tools) eliminating costly and failure-prone wiring.

b) Direct wireless power for wireless sensors and actuators, eliminating the need for expensive power wiring or battery replacement and disposal.

4) Transportation :

a) Automatic wireless charging for existing electric vehicle classes: golf carts, industrial vehicles.

b) Automatic wireless charging for future hybrid and allelectric passenger and commercial vehicles, at home, in parking garages, at fleet depots, and at remote kiosks. c) Direct wireless power interconnections to replace costly vehicle wiring harnesses and slip rings.

Fig. Automatic Wireless charging for Electric Vehicle.


5) Medical Application: Wireless charging systems are being developed for implanted medical devices including Left ventricular assist device (LVAD) heart assist pumps, pacemakers, and infusion pumps. Using highly resonant wireless power transfer, such devices can be efficiently powered through the skin and over distances much greater than the thickness of the skin, so that power can be supplied to devices deeply implanted within the human body. The HRWPT technique eliminates the need for drive lines that penetrate the human body, and for surgical replacement of primary batteries.

Fig. Wireless pacemaker and pain remover

6) Military Application: Designers of defence systems are able to utilize wireless charging to improve the reliability, ergonomics, and safety of electronic devices. The Talon Teleoperated robot shown in Figure 9 is being equipped with wireless charging so that it can be recharged while it is being transported by truck from site to site. Helmet mounted electronics, including night vision and radio devices can be powered wirelessly from a battery pack carried in the soldier’s vest, eliminating the need for disposable batteries or a power cord connecting the helmet to the vest mounted battery pack.

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Fig. Military robot and soldier helmet Military applications.BANASTHALI VIDYAPITH

DEPARTMENT OF ELECTRONICS[Type text]

FUTURE SCOPE

Modern science has now made it possible to use electricity without having to plug in any wires. This concept is called witricity which seems to have a bright future in providing wireless electricity.

Researchers developed witricity using resonance where energy is transmitted between two copper coils that resonate at the same frequency. Of these two coils, one is the power transmitter and the other, the receiver. The advantage of witricity is that there is no need of having a line of sight. As long as the object to be powered has a source of wireless power, in its vicinity, the appliacnce charges automatically without having to be plugged in.

Just imagine the future, with witricity, where there will be no need of power cables and batteries. The city just has to be covered with witricity hot spots wherein you can use your electric gadget battery and wire free making it more convenient to carry around and much lighter. With witricity, there will be no need of charging batteries, or buying new batteries for your electrical gadgets.

Just as beneficial witricity may be, there are some contraindications to the concept, with debates if it is risky living next to power lines and having a low power witricity network running in the home. They wonder what happens if a glass of water is spilt in a witricity room.

Fig.WiTricity House


However despite these contraindications, witricity has a bright future with the many advantages it provides in terms of weight, convenience and portability of electrical appliances.

The ability of our technology to transfer power safely, efficiently, and over distance will improve products by making them more convenient, reliable, and environmentally friendly. WiTricity technology can be used to provide:

Direct Wireless Power—All the power a device needs is provided wirelessly — no batteries are required. This mode powers devices that are always within range of its WiTricity power source.

Automatic Wireless Charging—A device with rechargeable batteries charges itself, while still in use or at rest, without requiring a power cord or battery replacement. This mode is used to charge mobile devices when in range of its WiTricity power source, without having to physically connect the device.

Fig.Wireless Charging

We can call WiTricity as future technology of Electricity transmission for power consumer. MIT's WiTricity is only 40 to 45% efficient and according to Soljacic, they have to be twice as efficient to compete with the traditional chemical batteries. The team's next aim is to get a robotic vacuum or a laptop working, charging devices placed anywhere in the room and even robots on factory floors.

WiTricity technology is designed to be directly embedded in the products and systems of Original Equipment Manufacturers (OEMs). We offer a number of development kits which will allow you to evaluate and adapt WiTricity wireless power into your own products. Or, you may prefer a custom engagement with our applications engineering team.


CONCLUSION

The transmission of power without wires is not a theory or a mere possibility, it is now a reality. The electrical energy can be economically transmitted without wires to any terrestrial distance. Many researchers have established in numerous observations, experiments and measurements, qualitative and quantitative. Cell phones, game controllers, laptop computers, mobile robots, even electric vehicles capable of re-charging themselves without ever being plugged in. Flat screen TV’s and digital picture frames that hang on the wall—without enquiring a wire and plug for power. Industrial systems and medical devices made more reliable by eliminating trouble prone wiring and replaceable batteries. Witricity Corp. is working to make this future a reality, developing wireless electricity technology that will operate safely and efficiently over distances ranging from centimeters to several meters—and will deliver power ranging from mill watts to kilowatts. Wireless transmission of electricity have tremendous merits like high transmission integrity and Low Loss (90 – 97 % efficient) and can be transmitted to anywhere in the globe and eliminate the need for an inefficient, costly, and capital intensive grid of cables, towers, and substations. The system would reduce the cost of electrical energy used by the consumer and get rid of the landscape of wires, cables, and transmission towers. This provides mid-range non-radiative energy transfer scheme based on l efficiency with respect to distance. As a powerful concept, it could enable a wide range of applications.

It has negligible demerits like reactive power which was found insignificant and biologically compatible. Many countries will benefit from this service. Monthly electric utility bills from old-fashioned, fossil-fuelled, loss prone electrified wire-grid delivery services will be optional, much like “cable TV” of today. Witricity Corp.’s vision is to develop a family of wireless electric power components that will enable OEM’s in a broad range of industries and applications to make their products truly “wireless.” Wireless electric power delivered over room scale distances, and with high efficiency. Wireless electric power that is safe for people and animals. Wireless electric power—imagine no more… it’s here!


REFERENCES

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http://sahyadri.edu.in/E-Journal/witricity.pdf

http://electronics.howstuffworks.com/everyday-tech/wireless-power.htm


http://electronics.howstuffworks.com/everyday-tech/wireless-power.htm

http://sahyadri.edu.in/E-Journal/witricity.pdf

http://www.buzzle.com/articles/witricity-wireless-electricity.html

http://revistagalileu.globo.com/Revista/Common/0,,EMI299116-17770,00-INVENCOES+FUTURISTAS+QUE+ESTAO+SENDO+CONSTRUIDAS+AGORA.html



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