Due to a lack of financial resources, we unfortunately have to suspend the import of any new radio frequency and mobile phone-related articles as of now (November 27, 2017). We apologize for this inconvenience and will keep you informed.

Because we received a large number of inquiries, we set up a bank account to accept donations. With their aid, we hope to resume, at least partly, the import of newly published articles to the RF archive of the EMF-Portal. Any contribution is greatly appreciated. Thank you for your kind support!

DONATION ACCOUNT: Uniklinik RWTH Aachen, IBAN: DE27 3905 0000 0013 0040 15, BIC: AACSDE33, Reference: GB-FM/380454/Arbm


Wireless charger for electric vehicles

The wireless charging of electric vehicles can be accomplished with two different technologies:
  1. For the Inductive Power Transfer (IPT) one primary and one secondary coil as well as a rectifier are required. The primary coil is thereby located on the ground beneath the vehicle and fed by alternating current. Due to the generated alternating magnetic field an alternating voltage is induced in the secondary coil which is positioned underneath the vehicle. The rectifier then converts the AC power into DC power before storage. Sometimes the vehicle has to be lowered for the sake of a more efficient energy transmission.
  2. For Magnetic Resonance Coupling (MRC) four instead of two coils are necessary: each two are located underneath the vehicle and inside the vehicle. The outer coils with each one turn are brought into resonance by an oscillating current and consequently generate an oscillating magnetic field which induces a voltage in the two inner coils with multiple turns. Thereby the wireless charging process can be performed up to distances of ten times the diameter of a coil.
Typical measurement values can be found in the database of exposure sources.
Demonstration of wireless charging during parking at the Tokyo Motor Show 2011
photo: NJo, license: CC BY-SA 3.0, via Wikimedia Commons