[RFI] RFI issues in electric (or hybrid) vehicles

Tue Apr 10 18:25:01 PDT 2012

Maybe the newer cars are better.  My son's is an 04.

Mike W0MU

W0MU-1 CC Cluster w0mu.net

On 4/10/2012 6:51 PM, Roger (K8RI) wrote:
> On 4/10/2012 6:40 PM, Dale Svetanoff wrote:
>> 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:
> We have a Prius Hybrid: No RFI issues to either the entertainment center
> or the rig.
> Most of the Hybrids I've seen/driven had too small a battery and light
> gauge wiring to run much of a radio. The battery is so small the
> manufacturer recommends you do not wire directly to the battery, but
> either through the switch, or a relay that is energized only when the
> ignition is on.  Two other hams have newer models and they do not have
> any RFI issues either.  I'd suggest a heavy duty battery placed in back
> along with a much larger alternator to keep it charged.
>
> The first sentence is a blanket statement that is not true: "To enable
> radio reception in electric vehicles, manufacturers must install filters
> and insulate cables, since electrical signals will otherwise interfere
> with music and speech transmissions" as I can point to 3 examples from
> different years that have no problems in either the car entertainment
> system, or the ham rigs.  I can understand filters when necessary and
> shielding, but "Insulation"?
>
> Therefor this appears as an article that was not well thought out or
> researched.
>
>> 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.)
> It works fine in Thunderbird.
>> 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.)
> The first sentence being a blanket statement that is not true hurt the
> credibility of the article and author.
>
>> 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.
> As I said above, I know of three hams who drive a Prius (all different
> years). Ours is one of the oldest ones, while a friend drives on about a
> year old.  No RFI issues at all.
>
>
> 73
>
> Roger (K8RI)
>
>> 73, Dale
>> WA9ENA
>> Sr. EMC Engineer
>>
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