Muriel,
Coilcraft has an app note that I found helpful:
http://www.webcom.com/liebman/us/reqnotes.html
Click on <FAX> or <PDF> for "Common mode filter design guide."
A couple of hints:
1. For Class I ITE, know your leakage current budget.
This will determine the maximum values of your Y-capacitors, and
2. use the standards to your advantage. For example, for ITE, the old
Vfg. 243/1991 had limits as low as 9 KHz. Now, the EN55022 limits
only go as low as 150 KHz. Usually, your cutoff frequency is
determined by your lowest switching harmonic _above_150_KHz_,
for ITE. Using the highest possible cutoff frequency requires
fewer turns on the common-mode choke(s.) This reduces intra-winding
capacitance, making the filter more effective at higher frequencies.
For more detail, click on <FAX> or <PDF> for "NEW! Common mode filter
inductor analysis."
Fewer turns makes the common-mode choke(s) less expensive, too.
3. Component selection, including your choice of cores, is critical.
(And no, I am not on Coilcraft's payroll.)
Good Luck,
Dan
> From [email protected] Tue Aug 25 15:07:37 1998
> Date: Tue, 25 Aug 1998 13:42:51 -0300
> From: Muriel Bittencourt de Liz <[email protected]>
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> Subject: Info on EMI Filters
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> Hello,
>
> I'm working with EMC at the field of power electronics and i'm
> interested in developing filters for conducted EMI. I've looked for
> designs at some books, but they aren't very practical.
>
> Could anyone send me some information 'bout some practical "guide to
> design of EMI filters"? Any information will be welcome.
>
> Muriel
>
>
>
> --
>
> ==================================================
>
> Muriel Bittencourt de Liz
> INEP - Instituto de Eletronica de Potencia
> Universidade Federal de Santa Catarina
> Caixa Postal - 5119
> 88.040-970 - Florianopolis - SC - BRASIL
> Phone: +55.48.331.9204 - Fax: +55.48.234.5422
> e-mail: [email protected]
> Homepage: http://www.inep.ufsc.br
>
> ==================================================
>
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