# Power in space(Wireless Power Transfer)

16 de Mar de 2014
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### Power in space(Wireless Power Transfer)

• 2.  What is wireless power transmission(WPT)?  Why WPT?  History of WPT  Types of WPT ◦ Techniques to transfer energy wirelessly  Advantages and disadvantages  Applications  Conclusion  References 2
• 3.  The transmission of power from one place to another without using wires, cables or chords  But, the wireless power transmission is made possible by using various technologies like microwaves, lasers and EM waves 3
• 4.  As per studies, most electrical energy transfer is through wires.  Most of the energy loss is during transmission • On an average, more than 30% • In India, it exceeds 40% Wireless Power Transmission 4
• 5. History of WPT: Tesla’s Expt  In 1899, Sir Nikola Tesla Proposed a method of Wireless Power Transmission.  As it is in Radiative mode, most of the Power was wasted and has less efficiency.  The efficient midrange power transfer concept is Witricity. In this model source and load are in Magnetic resonance so there is no power loss.
• 6. 6 CONCEPT OF ELECTROMAGNETIC WAVE: When an electric current passes through a wire, there is an electric field & magnetic field in the dielectric surrounding the conductor . The electric field of a circuit over which energy flows has three main axes which are mutually perpendicular to each other: a. The magnetic field, concentric with the conductor. b. The lines of electric force, radial to the conductor. c. The power gradient, parallel to the conductor.
• 7. RESONANCE COUPLING  A group of theoretical physicists at MIT came up with the idea to use resonant induction to transmit power wirelessly led by Dr. Marin Soljacic. “Resonance", a phenomenon that causes an object to vibrate when energy of a certain frequency is applied. The Rise Of The Fallen in 2007
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• 9.  Reliable  Efficient  Fast  Low maintenance cost  Can be used for short-range or long-range. 9
• 11.  The transfer of energy ◦ Magnetic coupling ◦ Inductive coupling  Simplest Wireless Energy coupling is a transformer 11
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• 14. 14 Inductive Coupling:  It uses magnetic fields that is produced due to current's movement through- wire. Bending the wire into a coil amplifies the magnetic field. The more loops the coil makes, the bigger the field will be.  This is the principle how a transformer works. Using it an electric toothbrush recharged. It takes three basic steps: 1. Current from the wall outlet flows through a coil inside the charger, creating a magnetic field. In a transformer, this coil is called the primary winding. 2. When you place your toothbrush in the charger, the magnetic field induces a current in another coil, or secondary winding, which connects to the battery. 3. This current recharges the battery.
• 15. 15 Need of Resonant coupling: Non-resonant coupled inductors(transformers,)work on the principle of inductive coupling is of short range power transfer & requires a magnetic core. Over greater distances the NRI Method is highly inefficient and wastes the majority of the energy in resistive losses of the primary coil. Hence concept of resonant coupling comes where two coils are tuned to a particular frequency called resonating frequency & absorb optimal energy.
• 18. 3/16/2014Wireless Power Transmission 18 Comparison with other technologies: In conventional transformers, for inductive transfer efficiency around 80% at short range  in witricity tightly coupled conventional transformers has efficiency around 90-95% . In addition, where batteries need periodic maintenance and replacement, resonant energy transfer can be used instead. So pollution due to Batteries during their construction and their disposal is largely avoided.
• 19.  Will it harm me?  Will it harm the environment?  Will it interfere with important communication? NO
• 20.  No wires  No e-waste  Need for battery is eliminated  Efficient energy transfer  Harmless, if field strengths under safety levels  Maintenance cost is less 20
• 21.  Distance constraint  Field strengths have to be under safety levels  Initial cost is high  In RIC, tuning is difficult  High frequency signals must be the supply  Air ionization technique is not feasible 21
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• 25.  Transmission without wires- a reality  Efficient  Low maintenance cost. But, high initial cost  Better than conventional wired transfer  Energy crisis can be decreased  Low loss  In near future, world will be completely wireless Wireless Power Transmission 25
• 26. 26  “Wireless Power Transmission”, Vol No.- 45, Electronics For U –August-2013  Peter Vaessen,” Wireless Power Transmission”, Leonardo Energy, September 2009  C.C. Leung, T.P. Chan, K.C. Lit, K.W. Tam and Lee Yi Chow, “Wireless Power Transmission and Charging Pad”  Wikipedia.  EFY posted articles on WPT.