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College Of Technology And EngineeringSubmitted toMr. P.C. BapnaAssociate ProfessorSubmitted byJAI LAL MEENAB.E. IVth Yr. (ECE)APresentation On“Inductive Charging”Maharana Pratap University of Agriculture andTechnology Udaipur
INTRODUCTIONInductive charging works on the basic principle inwhich two power systems are placed very close to oneanother. They need not to be exposed or connected toeach other. Each of these power systems contains anelectrical coil that stores electricity for the device’s use.The coils’ proximity to each other results in thegeneration of a low power electrical field that connectsthem.
This field allows the transfer of electricitybetween the two systems. The two systemsshare electricity until they both have exactlythe same amount of power. In inductivecharging, one of the devices, i.e., the sender,is constantly powered so that it can sendpower to the receiver continuously until thereceiver is fully charged.
Induction powers the charging mats thatwirelessly transfer energy to the devices and allowsthem to be recharged by simply placing them on thetop of the mat. Inside the mat there is an inductivecoil through which the electricity runs and thepower is transferred to a second coil attached to thedevice. Inductive charging uses an electromagneticfield to transfer energy between two objects.INDUCTIVE CHARGING
This is usually done with a charging station.Energy is sent through inductive coupling toan electrical device, which then can use thatenergy to charge batteries. There is a small gap between the two coilsemployed in each of the sender and receiverof the energy within the respective devicesdue to which inductive charging isconsidered a short-distance wireless energytransfer,
Induction chargers typically use an induction coil tocreate an alternating electromagnetic field from within acharging base station, and a second induction coil in theportable device takes power from the electromagneticfield and converts it back into electrical current tocharge the battery. The two induction coils in proximitycombine to form an electrical transformer.
11 Inductive Coupling:The most familiar example of a Inductive coupling is a transformer.In a transformer, a coil of wire with alternating current generates a time-varying magnetic flux, which couples into an adjacent coil of wire andgenerates a corresponding current on the secondary coil through magneticinduction.In a wireless inductive chargingsystem , the primary coil residesin the charging device, and thesecondary coil is locatedin the portable device. Thereforeit is necessary to use either anair gap transformer, or a split-core transformer with an air gapbetween the two cores toimprove the efficiency.
12Cont…When the secondary coil is broughtin close proximity to the primary coil,the transformer is formed and energytransfer occurs. This method ofwireless energy transfer can be fairlyefficient as the majority of themagnetic flux resides in the core of thetransformer, and therefore losses dueto leakage fields are low except at theair gap between the two cores.Due to the need for a small air gap even in split coretransformers, the efficiency is lower than more traditionaltransformer designs, and as the air gap increases theeffectiveness of the coupling is decreased significantly. Forthese reasons this method is only useful for energy transferover short distances.
Power losses occur because the changing magnetic fieldwill also induce currents in the iron core. These inducedcurrents are known as eddy currents. Eddy currents willgenerate heat and reduce the transformers efficiency. Inorder to reduce the formation of eddy currents, a laminatedcore is used.Current flowing through the primary and secondary coilswill generate heat. Low resistance copper wires is used toreduce this effect.LOSSES IN TRANSFORMER
The core is magnetised and demagnetised alternatelywhen AC current flows through the primary coil.Energy is lost during this process. This is known asHysterisis. This effect is reduced by using a soft ironcore.There may be a leakage of magnetic flux in theprimary coil. A special core design is used in atransformer to ensure that all the primary flux is linkedwith the secondary coil .
Charger output:Up to 850mA and up to 8.5 Volts. Maximum power: 20W+. Range: 1cm or less. Generally available in form of Charging pads.INDUCTIVE PROPERTIES
Power Mat 3X is a sleek, slim three position wireless chargingmat for home and office. A magnetic attraction between everyreceiver and each access point on every Mat assures thatalignment is precise and the most efficient charging occurs.Communication between the Mat and the Receiver allows themat to deliver an exact amount of power for the proper lengthof time so that the transfer of power is safe and efficient and noenergy is wasted. When the device reaches full charge, power isshut off to that device, which avoids overcharging of the devicesbattery as well as saves energy. Once full power is achieved andthe Auto Shut Off has occurred to save energy, the system willmonitor the status of the battery in the device. If the battery isused, the system will again initiate charging and return thebattery to a full charge.
Time varying magnetic fields can be used to transfer power acrossthe skin to drive implantable biomedical devices without the useof percutaneous wires. This system consists of two coils, one internal and one externalthat transmit power via magnetic force from an external batteryacross the skin without piercing the surface. The internal coil receives the power and sends it to the internalbattery and controller device.
22 Creation of a shock free environment . Reduction in power theft. A solution to reduce e-waste. Efficiency not affected by room geometry. Can charge multiple devices. Can deliver power through walls. No Need of transmission lines. Wireless chargers are cost effective,adaptable, portable and stylish.
23 Possibility of harmful radiation. Doesn’t have a very large range. Higher Initial Cost. Increase in distance decreasesefficiency. increased resistive heating. Slower charging.
24 Wireless charging has huge potential. This is why peoplehave been working on it for well over a century. If we couldmove power without wires we’d be able to re-think not justconsumer electronics but the infrastructure used by theentire human race. Transmission without wires become a reality. In future, world will be wireless. Future improvements in wireless power technology offerworld changing implications.