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Re: Ferrite materials (was Re: A CW TC without a tube + Re:
Hi Marco,
> Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi>
>
> Tesla List <tesla-at-pupman-dot-com> on 10.05.99 07:46:12
>
> To: tesla-at-pupman-dot-com
> cc: (bcc: Marco Denicolai/MARTIS)
> Subject: Re: A CW TC without a tube + Re: Solid state TC progress ?
>
> Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
>
> >> I received today a sample of a Siemens U93/76/30 core (U-U couple): that
> >is the
> >> biggest from Siemens! The problem is that the material is N27, which has
> >> reasonable losses up to 25 kHz (I use 50 kHz). Boy, that has got a Ve of
> >297000
> >> mm3 and an Ae of 840 mm2! Great size but not optimal material...
>
> >N27 is a great choice for your application IMO. (Philips equiv. 3C85)
>
> Not really. Here is a sample from Siemens and Philips databooks:
>
> f B 3C90 loss N27 loss
> kHz mT kW/m3 kW/m3
> 25 100 12 30
> 25 200 80 155
> 100 100 80 200
>
> 3C90 is slightly better than 3C85 and it is what I have ordered. As you can
> see,
> over 25 kHz the N27 losses rocket to sky. Already at 25 kHz they are
twice what
> I get with the 3C90.
I know the figures look pretty frightening but realise that the
volume of your core is << 1 cu. m. N27 is happily used in SMPS (with
flat-topped pulse drive) to at least 100kHz. If you really want to
go for the doctor, try N67. That wouldn't happen to be the 3C90
equivalent would it? If so, that material is used in resonant
supplies up to 1MHz. At any rate, the losses for N27 are vastly lower
than for powdered iron in your particular application.
Correct me if I'm wrong but based on your core volume, Bpk of
100mT and a frequency of 100kHz you'd be looking at a core loss of
about 60W with N27. That translates to about 24W with 3C90. Not bad
for a throughput of 5kW.
Please keep us posted.
Malcolm