IARU informuje, przestrzega - mamy nowe zagrożenie pasm amatorskich KF.
WPT-EV
Colleagues,
Please feel free to translate, to edit and to publish the following article.
73, Tom Kamp DF5JL
IARU Region 1 HF Manager
WPT-EV - The End of Shortwave?
No clutter, no dirty hands, no pitfalls - the car industry is convinced
that electric cars will be charged wirelessly in the future. The idea: A
high-frequency field inductively transmits the energy to a receiver coil
in the vehicle. The whole thing is called "Wireless Power Transmission
for Electrical Vehicles" (WPT-EV): For loading the driver parks his car
over a pad with the transmitter unit. It is charged with powers up to 20
kilowatts at 79 to 90 kHz. The efficiency should be up to 85 percent,
according to the developer companies.
Compared to wired charging stations, inductive charging technology
requires less space in the garage or parking garage. A comfortable
affair, then. But what happens when high energies are transmitted at
such frequencies? The IARU deals intensively with this question.
Although WPT-EV high-power charging systems do not work on amateur radio
frequencies, there is a strong fear that harmonics generated by these
systems and other out-of-band signals could cause interference in the
bands of other radio services - even in our amateur radio bands.
The amateur radio service is particularly vulnerable because it often
works with comparatively low signals. The Reverse Beacon Network (RBN),
a real-time database powered by hundreds of CW receiving stations around
the world, shows that more than half of these signals are at a
signal-to-noise ratio of less than 15 dB (at 500 Hz bandwidth). A
significant increase in the background noise level would therefore have
a very harmful effect on amateur radio. Even in rural environments,
noise levels have already risen, due to millions of low-power digital
devices (switching power supplies, LED lighting systems, etc.). Any
further significant deterioration of the background noise level will
affect the performance of the amateur radio service.
The current ITU limits for emissions in the noise region of short-range
devices are defined in ITU-R SM.329-12. There are indications that some
WPT-EV developers are using them as a basis for planning. Using these
limits, it is concluded that WPT-EV spurs could exceed the current
background noise level by up to 40-50 dB. The IARU believes that the
planned density of WPT-EV systems will have a significant impact on
radio traffic. A first study [1] shows that existing limits do not
provide adequate protection, and that without these limits being
tightened, the coexistence of radio communications services and WPT-EV
systems in the same environment is not possible.
But technology companies and the car industry are already considering a
next stage of wireless charging. In the so-called "Wireless Electric
Vehicle Charging" (WEVC), for example, a high-frequency magnetic field
with 85 kHz is generated in the roadway. This should allow loading in
flowing traffic. On a test track in Versailles, it has already been
possible to transmit powers of up to 20 kilowatts to the moving car.
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[1] IARU: Study of the Impact of Wireless Power Transfer Systems for
Electrical Vehicles Operating in the 79-90kHz Range on Radio
Communication Systems at the Amateur Service, 28 May 2018. See also:
https://bit.ly/2KhBDNA.
__._,_.___ Posted by: "HF Committee Chairman (C4)" <iaru-r1-hf@mail.ch>
Marek SP3AMO, HF Manager PZK
