Abstract: coils. There are two coils used, one

Abstract: This paper involves the details of the project entitled “wireless Power Transmission”. It is the system for transmitting the electrical power from the source to load wirelessly using coils. There are two coils used, one at the sending end and another at the receiving end. This project is not same like the wireless transmission of signals which we use in cell phones. In this mode of transmission, electrical power is transmitted in the form of magnetic rays. In this project, first primary coil converts the electrical power in the form of magnetic rays at the sending end side. Because of this flux will be produced. When secondary coil interact in this flux, an Electromagnetic Field (E.M.F.) will be produced in the secondary coil. In this way, electrical power will be transmitted without using the wires.Keywords: Electrical power Transmission, Coils, Magnetic Rays, Flux, E.M.F.INTRODUCTIONWireless Power Transmission (WPT) or Wireless Energy Transmission is the transmission of electrical energy from a power source to an electrical load, such as an electrical power grid or a consuming device, without the use of discrete human-made conductors. Wireless transmission is useful to power electrical devices in case where interconnecting wires are inconvenient, hazardous, or are not possible.This project is not same like the wireless transmission of signals which is used in cell phones. In this mode of transmission, electrical power is transmitted in the form of magnetic rays. Micro-waves are harmful to human beings as well as other living organisms, while magnetic rays are not harmful to any living organism. Here two objects having same resonating frequency and in magnetic resonance tend to exchange energy, while dissipating relatively little energy to the extraneous off-resonant objects.The wired wayThe majority of today’s residences and commercial buildings are powered by alternating current (AC) from the power grid. Electrical stations generate AC electricity that is delivered to homes and businesses via high-voltage transmission lines and step-down transformers.Electricity enters at the breaker box, and then electrical wiring delivers current to the AC equipment and devices that we use every day—lights, kitchen appliances, chargers, and so forth.All components are standardized and in agreement with the electrical code. Any device rated for standard current and voltage will work in any of the millions of outlets throughout the country. Here a cord, there a cord. Most of our electrical devices have AC power cords.NEED OF WIRELESS POWER TRANSMISSIONOne of the major issues in power system is the losses that occur during the transmission and distribution of electrical power. As the demand increases day by day, the power generation increases and the power loss is also increased.The major amount of power loss occurs during transmission and distribution. The percentage of loss of power during the transmission and distribution is approximated as 26 %. The main reason for power loss during transmission and distribution is the resistance of wires used for grid.1The efficiency of power transmission can be improved to certain level by using high strength composite overhead conductors and underground cables that use high temperature super conductor. But, the transmission is still inefficient.According to World Resources Institution (WRI), India’s electricity grid has the highest transmission and distribution losses in the world a whopping 27%. Numbers published by various Indian government agencies put that number at 30%-40% and greater than 40%. This is attributed to technical losses (grid’s inefficiencies) and theft. Power transmission using wires is not possible to every places and it doesn’t provide portability for the devices or instruments consuming power. 1The efficiency of power transmission can be increased by transmitting the power wirelessly. The concept of wireless electricity is not new. In fact it dates back to the 19th century, when Nikola Tesla used conduction based systems instead of resonance magnetic fields to transfer wireless power. As the method was radiative, most of the power was getting wasted.2Wireless Power Transfer (WPT) makes it possible to supply power through an air gap, without the need for current-carrying wires. WPT can provide power from an AC source to compatible batteries or devices without physical connectors or wires. WPT can recharge mobile phones and tablets, drones, cars, even transportation equipment. It may even be possible to wirelessly transmit power gathered by solar-panel arrays in space.WPT has been an exciting development in consumer electronics, replacing wired chargers. The 2017 Consumer Electronics Show will have many devices offering WPT.LITERATURE SURVEYThe concept of transferring power without wires, however, has been around since the late 1890s. Nikola Tesla was able to light electric bulbs wirelessly at his Colorado Springs Lab using electrodynamic induction (aka resonant inductive coupling).Fig 1. An image from Tesla’s patent for an “apparatus for transmitting electrical energy,” 1907.Three light bulbs placed 60 feet (18m) from the power source were lit, and the demonstration was documented. Tesla had big plans and hoped that his Long Island-based Wardenclyffe Tower would transmit electrical energy wirelessly across the Atlantic Ocean. That never happened owing to various difficulties, including funding and timing.6WPT uses fields created by charged particles to carry energy between transmitters and receivers over an air gap. The air gap is bridged by converting the energy into a form that can travel through the air. The energy is converted to an oscillating field, transmitted over the air, and then converted into usable electrical current by a receiver. Depending on the power and distance, energy can be effectively transferred via an electric field, a magnetic field, or electromagnetic (EM) waves such as radio waves, microwaves, or even light.6Wireless power transmission technologies use time-varying electric, magnetic, or electromagnetic fields. Wireless transmission is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.Wireless power techniques mainly fall into two categories, non-radiative and radiative. In near field or non-radiative techniques, power is transferred by magnetic fields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes. Inductive coupling is the most widely used wireless technology; its applications include charging handheld devices like phones and electric toothbrushes, etc. 3•    In 1826, Andre-Marie Ampere developed ampere’s circuital law showing that electric current produces a magnetic field. 1, 4 In 1831, Michael Faraday developed Faraday’s law of induction, describing the electromagnetic force induced in a conductor by a time-varying magnetic flux. 1, 4In 1862, James Clerk Maxwell synthesized these and other observations, experiments and equations of electricity, magnetism and optics into a consistent theory, derivingMaxwell’s equations. 1, 4This set of partial differential equations forms the basis for wireless power transmission using electromagnetic induction methodology that is to be used. 1Wireless power techniques mainly fall into two categories, non-radiative and radiative. In near field or                                                             non-radiative techniques, power is transferred by magneticfields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes. Inductive coupling is the most widely used wireless technology; its applications include charging handheld devices like phones and electric toothbrushes, RFID tags, and chargers for implantable medical devices like artificial cardiac pacemakers, or electric vehicles. 3A.  Far-field or radiative technique:In far-field or radiative techniques, also called power beaming, power is transferred by beams of electromagnetic radiation, like microwaves or laser beams. These techniques can transport energy longer distances but must be aimed at the receiver. Proposed applications for this type are solar power satellites, and wireless powered drone aircraft. 3B.  Near-field (nonradiative) technique:At large relative distance, the near-field components of electric and magnetic fields are approximately quasi-static oscillating dipole fields. These fields decrease with the cube of distance: (Drange/Dant) Since power is proportional to the square of the field strength, the power transferred decreases as (Drange/Dant) ?6 or 60 dB per decade. In other words, if far apart, doubling the distance between the two antennas causes the power received to decrease by a factor of 26 = 64. As a result, inductive and capacitive coupling can only be used for short-range power transfer, within a few times the diameter of the antenna device Dant, Unlike in a radiative system where the maximum radiation occurs when the dipole antennas are oriented transverse to the direction of propagation, with dipole fields the maximum coupling occurs when the dipoles are oriented longitudinally. 3C.  Qi Charging, an open standard for wireless charging:While some of the companies promising WPT are still working to deliver products, Qi (pronounced “chee”) charging is standardized, and devices are currently available. The Wireless Power Consortium (WPC), established in 2008, developed the Qi standard for battery charging. The standard supports both inductive and resonant charging technologies.Inductive charging has the energy passing between a transmitter and receiver coil at close range. Inductive systems require the coils to be in close proximity and in alignment with each other; usually the devices are in direct contact with the charging pad. Resonant charging does not require careful alignment, and chargers can detect and charge a device at distances up to 45mm; thus, resonant chargers can be embedded in furniture or mounted in shelvingThe presence of a Qi logo means the device is registered and certified by the Wireless Power Consortium.When first introduced, Qi charging was low power, about 5W. The first smartphones using Qi charging were introduced in 2011. In 2015, Qi was expanded to include 15W, which allows for quick charging.The presence of a Qi logo means the device is registered and certified by the Wireless Power Consortium.When first introduced, Qi charging was low power, about 5W. The first smartphones using Qi charging were introduced in 2011. In 2015, Qi was expanded to include 15W, which allows for quick charging.6PROPOSED SYSTEMThe above discussed problem can be solved by choosing an alternative option for power transmission which could provide much higher efficiency; low transmission cost and avoids power theft. Wireless Power Transmission is one of the promising technologies and may be the righteous alternative for efficient power transmission. Using Wireless Power Transmission maximum efficiency for the power transmission can be achieved.The power losses taking place during transmission and distribution by using conductors can be overcome to an extent as well as the efficiency of wireless power transmission using conduction based technique can be increased by using Resonant inductive coupling technique (electrodynamics coupling, strongly coupled magnetic resonance) as we can see in fig. 1 is a form of inductive coupling in which power is transferred by magnetic fields between two resonant circuits (tuned circuits), one in the transmitter and one in the receiver. Each resonant circuitconsists of a coil of wire connected to a capacitor, or a self-resonant coil or other resonator with internal capacitance. The two are tuned to resonate at the same resonant frequency. The resonance between the coils can greatly increase coupling and power transfer, analogously to the way a vibrating tuning fork can induce sympathetic vibration in a distant fork tuned to the same pitch. 3Fig 2-Resonant Inductive CouplingThe concept behind resonant inductive coupling is that high Q factor resonators exchange energy at a much higher rate than they lose energy due to internal damping. Therefore, by using resonance, the same amount of power can be transferred at greater distances, using the much weaker magnetic fields out in the peripheral regions (“tails”) of the near fields (these are sometimes called evanescent fields. Resonant inductive coupling can achieve high efficiency at ranges of 4 to 10 times the coil diameter (Dant). This is called “mid-range” transfer, in contrast to the “short range” of non-resonant inductive transfer, which can achieve similar efficiencies only when the coils are adjacent. Another advantage is that resonant circuits interact with each other so much more strongly than they do with non-resonant objects that power losses due to absorption in stray nearby objects are negligible. 3How is efficiency measured for wireless power transfer?Efficiency is measured in a general sense as the amount of power (as a percentage) that is transferred from the power source to the receiver device i.e. a wireless charging system for a smartphone with 80% efficiency means that 20% of the input power is being lost between the wall socket and the battery for the smartphone. The formula for measuring operating efficiency is:Efficiency=Dc power output/dc power input. 5Can power be transmitted through materials other than air?Yes. Power is able to be transmitted wirelessly through almost all non-metallic materials, including – but not limited to – solids like wood, plastics, textiles, glass and brick, as well as gases and liquids.When a metallic or electrically conductive material (i.e. carbon fiber) is placed within close proximity of an electromagnetic field, the metallic object will absorb the power from the magnetic field, and heat up as a result. This, in turn, affects the efficiency of the system due to power being lost through absorption. This is how induction cooking works – inefficient power transfer from the cooktop creates heat to enable cooking. This post on wireless charging and induction cooking provides a detailed explanation on this relationship.5ADVANTAGESElectricity can be transmitted at the places where wired transmission is not possible.High efficiency than wired power transmission.The power can be delivered in any direction.Not harmful to other living beingsNo need for meter rooms and electrical closets.Reduction of e-waste by eliminating the need for power cordsPortability since no wire is used between transmitter and receiver.VI.       APPLICATIONSTo act as a charging source for handheld devices like mobiles, laptops, tablets, etc.To supply power to electronic and electrical devices or  appliances.BLOCK DIAGRAM AND WORKINGWireless power transmission work on the principle of mutual induction between the two coils. There are two copper coils arranged one at the transmitting end and other at the receiving end, the transmitting coil is attached to the power source(230 volts, 50 Hz AC) while the second coil is attached to the receiving appliance/device. When the power is switched on the transmitting coil converts the input power into magnetic flux, which is oscillating at a particular frequency. This magnetic flux gets induced to the receiving coil in the proximity to the transmitting coil, which in turn produces E.M.F. at the receiver which can be used to supply power to any electrical device or component.Fig. 3 Block DiagramAs shown in the block diagram in fig. 2, 230 volts, 50Hz AC power is given to primary circuit at transformer input which is a step down transformer which then gives output to rectifier which gives pulsating DC and finally it is given to the oscillator circuit after smoothening  it using filter and regulating it using the voltage regulator.The oscillator used is an astable multivibrator using IC555 which is used 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 at the receiver is rectified and smoothened using rectifier and filter. Desired DC voltage can be obtained by using differed voltage regulator or a single variable voltage regulator.FIGURES REPRESENTING BLOCK DIAGRAMFig. 4 Transmitter CircuitFig. 5 Receiver CircuitFig. 6 Coil Set 1Fig. 7 Coil Set 2  OBSERVATIONSThe magnetic flux should satisfy certain conditions like it should be time varying, if not; no power transmission takes place.There is a loss of power transmission if there is a strongFerro-magnetic substance within the field created by the magnetic flux from transmitting coil.Possibility of “energy theft”. Someone can be using your power.As distance increases, efficiency decreases.RESULTSDifferent circuits and coils of different dimensions were designed and tested for this project and with that we concluded that as Magnetic wires are used here to design the coil which is the major component here ,it can give us maximum efficiency and its efficiency depend on various factors :AGW of the magnetic wire.Diameter of the coil.Number of turns of wire.Input oscillation frequency.Resonant  frequency  of  the  coil’s  (  Primary  and Secondary )CONCLUSIONAfter completion of this project it is concluded that, Faraday’s law of magnetic induction is the major factor here followed by Ampere’s law and Maxwell’s equations which helped us getting the desired conditions to get the output with maximum efficiency and one can successfully transfer the power wirelessly using magnetic induction with 80-90 % efficiency.FUTURE SCOPEThe circuit can be made more compact by using SMT-Surface Mount Technique for designing primary and secondary blocksThe coils can be designed on micro-stripline or strapline’s.Wireless power transmission is possible from electrical source to the consuming device or appliance, so it can also be used for transferring power from one device to another for example between mobile to mobile just like wireless sharing of data.

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