List mates:
The link below leads you to an article from Electronic Design magazine. It
concerns RFI issues in electric drive vehicles (and, by extension, hybrids, as
well). The primary focus is on the interference caused to the entertainment
system ("broadcast") radios within the vehicles. My personal view is that the
situation is almost surely applicable to communications radios, as well,
especially those used for HF communications.
Here is the link:
http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0000100&ISSUE=1204&RELTYPE=IN&PRODCODE=00000&PRODLETT=AI.html?et_cid=2583485&et_rid=60851216&linkid=http%3a%2f%2fwww.wirelessdesignmag.com%2fShowPR%7ePUBCODE%7e055%7eACCT%7e0000100%7eISSUE%7e1204%7eRELTYPE%7eIN%7ePRODCODE%7e00000%7ePRODLETT%7eAI&CommonCount=0
(Note: Due to length of the link, I hope it all comes thru the reflector
intact. I am in hopes that you will be able to click anywhere on the link and
succeed in getting to the article.)
To be honest, I was disappointed in the article's lack of substantial technical
detail. (Although Electronic Design is not a publication devoted specifically
to EMC/EMI issues, it is targeted to the electronic engineering community.
Therefore, I was a bit surprised that this article is pretty much at the lay
person level. Nevertheless, I felt that some of the comments might be of
interest to readers on this reflector.)
One aspect of the automotive RFI issue did catch my interest: A primary dictum
in RFI control is that you do all that you can to contain an RFI source (in
this case, the power converter) so as to minimize propagation of interference
via direct radiation or via the associated wires and cables. ("Containment"
also means that I/O lines should be well-filtered.) Note that nowhere in the
article is containment of the source mentioned. Instead, a lot of effort has
been placed on routing of wires and insulation of the high power drive motor
from the chassis of the vehicle. (These motors are typically electronically
commutated DC types, no brushes.) One must guess that size, weight, and cost
probably factor into the decisions to work placement and isolation issues,
rather than containment.
I, for one, would be delighted if someone in the automotive industry would
reply to this posting with some supporting information as to what is being done
in today's electric and hybrid drive vehicles for RFI control, especially as
regards communications (be it for broadcast or two-way applications). I would
also welcome comments from anyone associated with the Fraunhofer Institute and
the work described in the article.
Finally, I am wondering if any list members have installed either a ham rig (HF
and/or VHF/UHF) or a scanner in an electric drive nor hybrid vehicle, and if
so, were there any significant RFI issues to contend with? Please post so that
we can all share in your experiences. Thanks.
73, Dale
WA9ENA
Sr. EMC Engineer
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