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A PAPER PRESENTATION ON
2 UNWIRED CHARGING TRULY WIRELESS WORLD (AUTONOMOUS) Presented ByV.ASHWINI D.MALLESWARAMMAIII-B-Tech, EEE III-B-Tech, EEEJNTU COLLEGE OF Engg, JNTU COLLEGE OF EnggAnantapur, AnantapurAndhra Pradesh Andhra PradeshE-mail: Ashwinivanam@gmail.com E-mail: firstname.lastname@example.orgPh.no-8099858086 ph.no-9640261495
3 range of power by the technique used inABSTRACT: this concept called “power casting”. This Yes, now we can forget wires technology uses radio frequency waveseven for charging. My mobile have been for carrying power.switched off, my Laptop computer have The efficient mid-range power can beno charging …….no such questions! transmitted to any device which uses thatCan we imagine the life without range of power by the technique used inelectrical wires? from now, answer to this concept called “eCoupling”. Thisthis question is yes. The methods technology uses electro magneticproposed in the present paper though coupling for carrying power.utilizes contrasting technologies for wire Now a days there is a Rapidless transmission of power namely development of autonomous electronics‘power cast technology’ and ‘eCoupled like Laptops, Cell-phones, House-holdtechnology’ are presented in the name of robots and all the above devices“unwired charging”, Which will typically rely on chemical energyfacilitate to Transfer power without storage(Battery) .As they are becomingusing wires. daily needs to present generation, The efficient low-range power can be Wireless energy transfer would be usefultransmitted to any device which uses that for many applications as above and they
4need low-range and mid-range energy. only by connecting the device to theThis is the main reason to prepare this supply through electrical Wires. Moreconcept. often it looks like snakes ……cables, cables…..and more cables… as shown INTRODUCTION:In our day-to-day life we use laptopcomputers, cell phones, digital cameras,voice recorder, portable printer,MP3players all plays a significant role.But the major limitation is that they haveto be charged regularly which is possible But this dream of wire less charging spare time to even think about themmight be possible very soon, by means seriously!of technology explained below. Unless Radio frequencies are foundational forthis concept is not implemented we can’t most devices we use today right fromreally call the world as really wire free TVs and radios to mobile phones. Butworld. This is because although wireless we ever think of how powerful the radiomantra is a old concept over the world frequencies are?we still need electric wires and chemical The simple example that makes radiobatteries for purpose of charging and frequency identification (RFID) superiortransmitting power. to barcodes is that they can store moreTECHNOLOGY: data, they can be read and written to,Power casting technology: they can be re-used etc., but what makes The Basic Idea: all this possible? How is RFID chip able If we walk a few meters from to survive on its own, woven into somewhere we are standing now we will product or person, isolated from the restprobably be cutting across at least a of civilization? It is because the chip isdozen radio waves zipping invisibly able to charge itself through the radioacross our room that is how common waves transmitted by the transceiverthey are…. So common that we barely when reading or writing. Basically this is
5a simple example of the energy carrying nanometer from perfection may all soonproperty of radio waves be a thing of the past. The power cast wireless power platform consists of a transmitter called ‘power caster’ and a receiver called ‘power harvester’. The ‘power caster’ can double the effective range, compared to normal RF transmitters and a power harvester can harvest up to 70% of the theoretical maximum power with in the Then why cannot RF (Radio range and convert it into dc current forFrequency) be used to power devices? the device to use. The power harvester is If we have a Base station that a chip about half the size of an ordinarydraws power from a power line and battery used for charging and must bekeeps transmitting it as radio waves and accompanied by a small antenna whoseall our mobile devices have receivers size varies according to the frequency ofthat can receive these radio waves and transmitted power. It can fit quiteconvert them into DC current, that’s comfortably into the batterypretty much a wire less powering compartment of most devices, and manysystem. That is one base station can devices could use the case itself as thecharge quite number of devices-provided antenna. Of course small tweaks in thethey all have the receivers built into circuitry of the device will be needed tothem this is precisely how the power cast connect the power harvester to it.system worksTECHNOLOGY BEHIND THE The power harvester is available inPOWER: various models for multiple frequency ranges, voltage requirements sizes and The mess of wires, those power strips so on. The design can fully customizedoverloaded with transformers and according to the requirements. Anymaddening gadget connectors half a device fitted with a power harvester gets charged automatically whenever it is
6with in the range of power caster and Radio waves are in fact energy. Theyany number of ‘power harvesting are already used to send and receive celldevices’ can be placed within the range phone, television, radio, and ‘Wi-Fi’of single power caster. This does not signals every day. Those waves spreadgive rise to problems like cancellation out in all directions until they reach anand interference because power caster antenna that is tuned to the appropriateneither causes nor is affected by such frequency. Power casts wireless powerproblems. In-fact, the power harvesters platform uses a "Power caster"actually outwit noises by making use of transmitter circuit running onthem. conventional current to broadcast a low- power radio signal at a predeterminedPOTENTIAL POWER frequency. The smaller "PowerHARVESTERS: harvester" receiver circuit which can be embedded in any low-power device then All the devices cannot be powered uses that energy to recharge or can evenusing power cast system only devices replace the devices battery.that work on AA, AAA batteries or cellbatteries can make use of this wire less The Power cast solution is able topower system. Power cast is designed to maximize power transfer by using apower devices with very low power. much broader area of the RF spectrum,Sensor networks, hearing aids, headsets the 900-MHz band. While notetc., are ideally suited for this necessarily a replacement for atechnology basically any device which conventional charger, the technologyrequires small battery (to be recharged) will be able to "trickle charge" a varietyare requires very little power for direct of electronics over a period of time sopowering (such as Light Emitting Diode that their energy is never fully depleted.LED) is suitable for taking advantage ofpower cast technology. Power cast As with a traditional AM/FM radio,technology is designed to provide milli the closer one is to the towerwatts of power to devices with in an transmitting the signal, the better theeffective range of the transmitter. reception. Power casts wireless platform operates using a similar principle. The
7wireless power platform can harvest a regime of operation. If one can operatefew milli watts of energy within a meter in that regime in a given system, theof the source, in this case the transmitter. energy transfer is expected to be veryThat is enough energy to charge a single efficient. Midrange power transferdepleted cell phone battery about half implemented in this way can be nearlyway overnight. The solution will also be omni directional and efficient,ideal for devices with small batteries irrespective of the geometry of thesuch as watches, hearing aids, wireless surrounding space, with low interferencekeyboards and mice, and game and losses into environmental objects.controllers, all of which could be The above considerations applycontinuously charged. But there are irrespective of the physical nature of thelimits to the charging capabilities the resonances.Power cast platform. Larger devices Magnetic resonances arewill not be able to make use of this particularly suitable for everyday‘power cast’ technology solution simply applications because most of thebecause they require too much power. In common materials do not interact withfact, the size limit for now seems to be at Magnetic Fields, so interactions withthe cell phone level for effective Environmental objects are suppressedcharging. even further. We were able to identifyeCoupled technology: the strongly coupled regime in the system of two coupled magneticThe Basic Idea: resonances by exploring Non-radiative The basic concept behind this is (near-field) magnetic resonant inductionMagnetic Resonance. Two resonant at Megahertz frequencies.objects of the same resonant frequencytend to exchange energy efficiently,while dissipating relatively little energyin extraneous off-resonant objects. Insystems of coupled resonances, there isoften a general “Strongly Coupled”
8Experimental Design: Our experimental schemeconsists of two Self-resonant coils. Onecoil (source coil) is coupled inductivelyto an oscillating circuit; the other (device Efficiency of the System:coil) is coupled inductively to a resistive The efficiency of the system isload. Self-resonant coils rely on the nothing but the ratio of output power tointerplay between distributed inductance input power. The output power isand distributed capacitance to achieve nothing but the device power rating andresonance. input power is sum of the power The coils are made of an dissipated by source, power loss due toelectrically conducting wire of total decay and output power.length ‘l’ and cross-sectional radius ‘a’, Efficiency=Pw / (Ps+Pd+Pw)wound into a helix of ‘n’ turns, radius The experiment done in 7th June,‘r’, and height ‘h’. There is no exact 2007 by the Massachusetts Institute ofsolution for a finite helix in the Technology, Cambridge gives the resultliterature, and even in the case of that in order to get 60W approximateinfinitely long coils, the solutions rely on power is the output useful power withassumptions that are inadequate for this 40% efficiency. They resonated thesystem. So here the method implemented circuit at ≈9.9 MHz so that theyis simple Quasi-static model to find the developed the power is transmitted up toparameters. Those are in Electro 8 times greater than the radius of the coilMagnetic equations. used. ADVANTAGES OF ABOVE TECHNOLOGIES: • The need for batteries and numerous redundant adaptors which consists of toxic
9 substances like nickel, cadmium, • As eCoupled technology is based mercury are reduced. This on magnetic resonance it could reduces the electronic waste. be easily effected by presence of • There is no need for alkaline Ferro magnetic materials in its batteries which are to be path. recharged regularly. • In eCoupled technology as the • Complexity and risk of electric device is close to the charging shorts reduces as we are not source it is able to provide more using any electrical wires. power than while charging using • Unaffected by the day night RF. cycle, weather or seasons. • Inductive method gives higher • This is an eco friendly and the power at shorter distances but system poses no health hazards power cast system though gives what so ever as the power limits. low range power it transmits • It is a boon for the devices which even at longer distances. use low-range and mid-range • In eCoupled technology the power resonance condition should beCOMPARISON BETWEEN ABOVE satisfied, if any medium error isTECHNOLOGIES: there possibility of power • Power cast technology is suitable transfer is affected, while as for only low range power, while power cast system uses radio eCoupled technology is suitable waves it is independent of for both low-range and mid- medium around it. range powers • In power cast technology any • Power cast technology is number of power harvesting effective even though the devices can be placed with in the distance between transmitter and range of single power caster. It receiver is high but major is not possible in case of limitation of eCoupled eCoupled technology technology is air gap should be CONCLUSION: low.
10 From the above discussion we can placed anywhere in the range ofconclude that no technology can be transmitter.perfectly ideal by making use of bestideas in the technologies andworking in conjunction with themwe can achieve wireless powertransmission very sooner. Thisreduces the risk of using electricalcables and redundant adaptors. Eachof the above system has its own prosand cons and one needs to decidebased on one’s needs. This is the Christmas tree which islighted based on power transmissionby radio frequency waves usingpower cast technology. It can be