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

[Dale Svetanoff]

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