WIRELESS ELECTRICITY (WITRICITY)

1ANKUR JAIN, 2GURNEET SINGH MAKKED, 3NEERAJ MODI

1Department of Electronics & Communication, Mandsaur Institute of Technology, Mandsaur, Madhya Pradesh, India 2,3Department of Electronics & Communication, Mandsaur Institute of Technology, Mandsaur, Madhya Pradesh, India

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.

Keywords- Witricity, Electrical resonance, electromagnetic induction, charging algorithm, power capturing device.

I. INTRODUCTION distance of 1 mile at 84% efficiency without using cables. Researchers developed several technique for Wireless electricity or witricity is the transfer of moving electricity over long distance without wires. electric energy or power over a distance without the Some exist only as theories or prototypes, but others use of wires. In our present electricity generation are already in use. onsider an example, in this electric system we waste more than half of its resources. devices recharging without any plug-in. The device Especially the transmission and distribution losses are which can be recharged is placed on a charger. the main concern of the present power technology. Supply is given to the charger and there is no Much of this power is wasted during transmission electrical contact between charger and device. The from power plant generators to the consumer. The recharging takes place in following steps. resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the 1. Current from the wall outlet flows through a coil energy generated. This loss implies that our present inside the charger, creating a magnetic field. In a system of electrical distribution is only 70-74% transformer, this coil is called the primary winding. efficient. We have to think of alternate state - of - art technology to transmit and distribute the electricity. 2. When the device placed on the charger, the Now- a- days global scenario has been changed a lot magnetic field induces a current in another coil, or and there are tremendous development in every field. secondary winding, which connects to the battery. If we don’t keep pace with the development of new power technology we have to face a decreasing trend 3. This current recharges the battery. in the development of power sector. The transmission of power without wires may be one noble alternative for electricity transmission.

II. ORIGINATION

Wireless power transmission is not a new idea. Nickolas Tesla demonstrated transmission of electrical energy without wires in early 19th century. Tesla used electromagnetic induction systems. 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 Fig. Shows charging of battery

Proceedings of IRF International Conference, 13th April-2014, Pune, India, ISBN: 978-93-84209-04-9 34 Wireless Electricity (Witricity) III. PRINCIPLE OF WITRICITY the swing absorbs is maximized when the pushes are 'in phase' with the swing's oscillations, while some of It revels the main idea of the “resonance condition” the swing's energy is actually extracted by the between two circuits”. A. Electrical resonance: - opposing force of the pushes when they are not. Electrical resonance occurs in an electric circuit at a Resonance occurs widely in nature, and is exploited particular resonance frequency when the impedance in many man-made devices. It is the mechanism by between the input and output of the circuit is at a which virtually all sinusoidal waves and vibrations minimum (or when the transfer function is at a are generated. Many sounds we hear, such as when maximum). Often this happens when the impedance hard objects of metal, glass, or wood are struck, are between the input and output of the circuit is almost caused by brief resonant vibrations in the object. zero and when the transfer function is close to one. Light and other short wavelength electromagnetic Resonance of a circuit involving capacitors and radiation is produced by resonance on an atomic scale, inductors occurs because the collapsing magnetic such as electrons in atoms. field of the inductor generates an electric current in its windings that charges the capacitor, and then the discharging capacitor provides an electric current that builds the magnetic field in the inductor, and the process is repeated continually. Formula of resonance frequency:

where ω = 2πf, in which f is the resonance frequency in hertz, L is the inductance in henries, and C is the capacitance in farads when standard SI units are used.

IV. QUESTIONS TO BE ADDRESSED

This research is going to address the following 4.2. CONDITIONS FOR WITRICITY CHARGING questions and hypotheses. What kinds of optimization  The first condition necessary is that charging problems will be useful to solve in the wireless must be able to occur through physical objects. electricity charging protocol for wireless sensor If the witricity cannot be passed through networks? How each of the optimization problems physical objects then the charging can only can be modeled using mixed integer programming? occur in a perfect unobstructed environment. This is not realistic because there are objects all 4.1. METHOD FOR WIRELESS POWER around us that can interfere with the TRANSMISSION transmission of the energy. Research thus far The method used for wireless power transfer is the has found that witricity can be transmitted electrical is the electrical transformer. In this the through wood, gypsum wallboard, plastics, electrically isolated from each other. The transfer of textiles, glass, brick, and concrete. energy takes place by electromagnetic coupling  The second condition necessary is that charging through mutual induction. The main drawback of this must be safe and not pose any sort of threat or method is the short range. For efficient working of a safety hazard to humans or animals. Since this system, which uses this method, the receiver must be type of energy transfer is non-radioactive it is in very close proximity to the-transmitter. A larger, safe for humans and animals. stronger field can be used for energy transfer over  The third condition necessary is that witricity large distance, but this process is extremely charging must be able to provide electricity to inefficient. Since magnetic field spreads in all remote objects without the use of wires. direction, making a large wastage of energy. Pushing Therefore, the energy must be transferable from a person in a swing is a common example of the transmitter to the capturing device over a resonance. The loaded swing, a pendulum, has a certain distance. natural frequency of oscillation, its resonant  The fourth condition necessary is that the frequency, and resists being pushed at a faster or witricity is able to transfer a meaningful amount slower rate. One familiar example is a playground of energy, or else it would defeat the purpose of swing, which acts as a pendulum. Pushing a person in the energy transfer. a swing in time with the natural interval of the swing

(its resonance frequency) will make the swing go 4.3. PARAMETERS higher and higher (maximum amplitude), while  The first parameter is the degree of charging. attempts to push the swing at a faster or slower tempo There are three different degrees in which a will result in smaller arcs. This is because the energy sensor can be charged. The first is perfect

Proceedings of IRF International Conference, 13th April-2014, Pune, India, ISBN: 978-93-84209-04-9 35 Wireless Electricity (Witricity) charging, this type of charging charges all the We have obtained following conclusions for batteries of the sensors until they are all full. increasing the distance:- This is achieved by using an external power  Diameter of the coil should increase source such as a base station or using proportionally with the frequency of designated power supply devices. The second operation. way is limited charging, this type of charging  A large diameter of source coil with a large charges the batteries of the sensors that are at or number of turns increases the distance of the above a certain threshold. It could have an operation. external power source, but if it does not it will  Limitation: we cannot increase the voltage try to maximize the network lifetime without of the operation above 50 to 60 volt because creating a blind spot in the wireless sensor it is dangerous for human body and can be network. caused for electric shock.

 The second parameter is the type of charging VI. HOW WOULD BE THE FUTURE WITH algorithm. There are two different charging WITRICITY algorithms; distributed and centralized. The distributed algorithm calculates the amount of Modern science has now made it possible to use energy that needs to be transferred between a electricity without having to plug in any wires. This node and its direct neighbor based on concept is called witricity which seems to have a information received from its direct neighbor. bright future in providing wireless electricity. The centralized algorithm calculates the amount of energy that needs to be transferred between The technology used for wireless power transmission all the sensors in the network. is known as witricity. Wireless power transmission is  The third parameter is the type of power supply. not a new idea; Nikola Tesla proposed theories of There is a base station and either all of the wireless power transmission in the late 1800s and sensors or some of the sensors are indicated as a early 1900s. Tesla's work was impressive, but it did percentage between 0 and 100%. It also allows not immediately lead to wide spread practical the base station to select a set of certain sensors. methods for wireless power transmission. Since then There are also designated power supply devices many researchers have developed several techniques that are non-sensor power supply devices that for moving electricity over long distances without are deployed in the WSN. wires. Some exist only as theories or prototypes, but others are already in use. In 2006 researchers at  The fourth parameter is the type of power Massachusetts Institute of Technology led by Marine capturing device. There is a base station and the Soijacic discovered an efficient way to transfer power sensors are indicated as percentages too, the between coils separated by a few meters. They have difference is the devices and base station might dubbed this technology as witricity. Witricity is based be a power capturing device or act as an upon coupled resonant objects. Two resonant objects intermediate power relay device. of the same resonant frequency tend to exchange energy efficiently, while not interchanging the V. OBSERVATIONS surroundings. The researchers demonstrate the ability to transfer 60W with approximately 40% efficiency We are also researching on the WITRICITY and we over distance in excess of 2 meters. Currently the have taken following observations:- project is looking for power transmission in the range of 100watts. As witricity is in the development stage, lot of work is to be done in improving the range of power transmission and efficiency.

VII. 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.

Proceedings of IRF International Conference, 13th April-2014, Pune, India, ISBN: 978-93-84209-04-9 36 Wireless Electricity (Witricity)  Does not interfere with radio waves. is transferred, which is much less efficient than regular wired connections.  Does not interfere with radio waves.  Cost: The cost of developing and implementing wireless energy networks  Wastage of power is small - Electromagnetic means that it would be too expensive for the waves would tunnel, they would not end-user to afford at this point. propagate through air to be absorbed or dissipated. So the wastage is small. CONCLUSION

 Highly efficient than electromagnetic The transmission of power without wires is not a induction - Electromagnetic induction theory or a mere possibility, it is now a reality. The system can be used for wireless energy electrical energy can be economically transmitted transfer only if the primary and secondary without wires to any terrestrial distance. Many are in very close proximity. Resonant researchers have established in numerous induction system is one million times as observations, experiments and measurements, efficient as electromagnetic induction qualitative and quantitative. Cell phones, game system. controllers, laptop computers, mobile robots, even electric vehicles capable of re-charging themselves  Less costly - The components of transmitter without ever being plugged in. Flat screen TV’s and and receivers are cheaper. So this system is digital picture frames that hang on the wall—without less costly. enquiring a wire and plug for power. Industrial systems and medical devices made more reliable by VIII. APPLICATIONS eliminating trouble prone wiring and replaceable batteries. Witricity Corp. is working to make this Witricity has a bright future in providing wireless future a reality, developing wireless electricity electricity. There are no limitations in Witricity technology that will operate safely and efficiently power applications. Some of the potential over distances ranging from centimeters to several applications are powering of cell phones, laptops and meters—and will deliver power ranging from mill other devices that normally run with the help of watts to kilowatts. Wireless transmission of batteries or plugging in wires. Witricity applications electricity have tremendous merits like high are expected to work on the gadgets that are in close transmission integrity and Low Loss (90 – 97 % proximity to a source of wireless 'power, where in the efficient) and can be transmitted to anywhere in the gadgets charges automatically without necessarily, globe and eliminate the need for an inefficient, costly, having to get plugged in. By the use of witricity there and capital intensive grid of cables, towers, and is no need of batteries or remembering to recharge substations. The system would reduce the cost of batteries periodically. If a source is placed in each electrical energy used by the consumer and get rid of room to provide power supply to the whole house. the landscape of wires, cables, and transmission Witricity has many medical applications. It is used towers. for providing electric power in many commercially available medical implantable devices. Another It has negligible demerits like reactive power which application of this technology includes transmission was found insignificant and biologically compatible. of information. It would not interfere with radio Many countries will benefit from this service. waves and it is cheap and efficient. Monthly electric utility bills from old-fashioned, fossil-fuelled, loss prone electrified wire-grid delivery IX. LIMITATIONS OF WIRELESS ENERGY services will be optional, much like “cable TV” of today. Witricity Corp.’s vision is to develop a family A number of companies and academic institutions of wireless electric power components that will (including Intel and MIT) are involved in a race to be enable OEM’s in a broad range of industries and the first to release marketable wireless energy applications to make their products truly “wireless.” packages; however, there are a number of limitations Wireless electric power delivered over room scale to the full implementation of wireless energy transfer: distances, and with high efficiency. Wireless electric power that is safe for people and animals. Wireless  Size: The copper rings which create electric power—imagine no more… it’s here! resonance and energy are simply too big for them to be part of any wireless energy ACKNOWLEDGMENT package.  Range: The range of wireless energy transfer I would like to thanks to our principal, staff of is just a few meters, which is a major hurdle. Mandsaur Institute of Technology, Mandsaur, for their kind support and providing facility to do my  Efficiency: Wireless energy transfer ensures research work. between 45% and 80% of the energy put in

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