Wireless power transfer

Inductive charging pad for a smartphone as an example of near-field wireless transfer. When the phone is set on the pad, a coil in the pad creates a magnetic field[1] which induces a current in another coil, in the phone, charging its battery.

Wireless power transfer (WPT), wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link. In a wireless power transmission system, an electrically powered transmitter device generates a time-varying electromagnetic field that transmits power across space to a receiver device; the receiver device extracts power from the field and supplies it to an electrical load. The technology of wireless power transmission can eliminate the use of the wires and batteries, thereby increasing the mobility, convenience, and safety of an electronic device for all users.[2] Wireless power transfer is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.

Wireless power techniques mainly fall into two categories: near field and far-field.[3] In near field or non-radiative techniques, power is transferred over short distances by magnetic fields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes.[4][5][6][7] Inductive coupling is the most widely used wireless technology; its applications include charging handheld devices like phones and electric toothbrushes, RFID tags, induction cooking, and wirelessly charging or continuous wireless power transfer in implantable medical devices like artificial cardiac pacemakers, or electric vehicles.

In far-field or radiative techniques, also called power beaming, power is transferred by beams of electromagnetic radiation, like microwaves[8] or laser beams. These techniques can transport energy longer distances but must be aimed at the receiver. Proposed applications for this type include solar power satellites and wireless powered drone aircraft.[9][10][11]

An important issue associated with all wireless power systems is limiting the exposure of people and other living beings to potentially injurious electromagnetic fields.[12][13]

  1. ^ The pad senses when a phone is on it and turns on the field. The pad uses a small amount of energy when not in use, however in modern wireless systems this "off" power is very small compared to the power used when charging. Hoffman, Chris (15 September 2017). "How Does Wireless Charging Work?". How-To Geek. How-To Geek LLC. Retrieved 11 January 2018.
  2. ^ Ibrahim, F.N.; Jamail, N.A.M.; Othman, N.A. (2016). "Development of wireless electricity transmission through resonant coupling". 4th IET Clean Energy and Technology Conference (CEAT 2016). pp. 33 (5 .). doi:10.1049/cp.2016.1290. ISBN 978-1-78561-238-1.
  3. ^ Kracek, Jan; Mazanek, Milos (June 2011). "Wireless Power Transmission for Power Supply: State of Art" (PDF). Radioengineering. 20 (2): 457–463.
  4. ^ Cite error: The named reference ECN2011 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Trancutaneous Capacitive Wireless Power Transfer was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Capacitive Elements for Wireless Power Transfer to biomedical implants was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Capacitive Wireless Power Transfer to biomedical implants was invoked but never defined (see the help page).
  8. ^ Miguel Poveda-García; Jorge Oliva-Sanchez; Ramon Sanchez-Iborra; David Cañete-Rebenaque; Jose Luis Gomez-Tornero (2019). "Dynamic Wireless Power Transfer for Cost-Effective Wireless Sensor Networks using Frequency-Scanned Beaming". IEEE Access. 7: 8081–8094. Bibcode:2019IEEEA...7.8081P. doi:10.1109/ACCESS.2018.2886448.
  9. ^ Bush, Stephen F. (2014). Smart Grid: Communication-Enabled Intelligence for the Electric Power Grid. John Wiley & Sons. p. 118. ISBN 978-1118820230.
  10. ^ "Wireless energy transfer". Encyclopedia of terms. PC Magazine Ziff-Davis. 2014. Retrieved 15 December 2014.
  11. ^ Marks, Paul (22 January 2014). "Wireless charging for electric vehicles hits the road". New Scientist.
  12. ^ Lu, Yan; Ki, Wing-Hung (2017). CMOS Integrated Circuit Design for Wireless Power Transfer. Springer. pp. 2–3. ISBN 978-9811026157.
  13. ^ Sun, Tianjia; Xie, Xiang; Wang, Zhihua (2013). Wireless Power Transfer for Medical Microsystems. Springer Science and Business Media. ISBN 978-1461477020.

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