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From: firstname.lastname@example.org (Nico Coesel)
Subject: Re: My flyback experiment is on the web
Date: Mon, 14 Oct 2002 09:58:53 GMT
NNTP-Posting-Date: Mon, 14 Oct 2002 10:00:33 +0000 (UTC)
X-Newsreader: Forte Free Agent 1.21/32.243
Chris Carlen wrote:
>Here is the URL to my web page showing the results of my most recent
>experiments with a flyback converter. I still haven't gotten a PWM chip
>hooked up yet, as my first goal was to buy some inductors that look like
>they are designed for switching supplies, and see if they'd work better
>than the hand wound transformer I made from a PC power supply core.
>Actually, the inductor seems a bit worse :-(
>All the details are on the web page.
>My main question is why does the inductor get so warm? I figured I
>wasn't really pushing it too hard, so it shouldn't loose much power.
>but it seems most of my losses are occurring in the inductor. I was
>hoping to avoid complex topologies such as a two transistor flyback,
>which requires a transformer, but lends itself to easily shunting the
>remaining core energy back to the input rail. Can that be done with the
>simple flyback that I am working with? I figured I could get 75% or
>better, so I'm not really far off. But I don't like heating the
>inductor, and I want to push up the power another 25% from what I'm
>testing at before I finish.
>I have a smaller inductor, and a larger one too, but all of the toroidal
>type, designed for 150kHz switchers.
>Comments appreciated on what steps I might take to make this simple
>circuit move in the direction of something worth committing to FR-4.
Strange; I've designed a similar converter (48V in, 168V / 100mA
@100kHz) but didn't have problems with the inductors. I've used 2
newport power filtering 100uH inductors in series (didn't have 200uH
I see there is also some ringing in your circuit. Did you try to put a
small snubber accross the drain and ground? Did you also consider
simulating the circuit?
Reply to nico@nctdevpuntnl (punt=.)
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