From: Chris Carlen
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Subject: Re: 87% All that vector calculus paid off
Date: Mon, 23 Dec 2002 03:11:30 GMT
NNTP-Posting-Date: Sun, 22 Dec 2002 19:11:30 PST
Tony Williams wrote:
> In article ,
> Chris Carlen wrote:
>>I had my wife wind 32 turns of 26 ga. on the spool last night, and she
>>did a real nice job for her first inductor. This morning I soldered the
>>leads onto the bobbin pins, and gapped the core with several layers of
>>packing tape, measured to exactly 0.18+/-0.01mm with a digital caliper.
>> So that gives an effective gap of 0.36mm. That should produce an
>>Al=100 and ue=140. So I figured I can sustain 1.14A before exceeding
>>160mT, and with switching around 180kHz, I'd need 47V input to pump 12W
>>through the thing, which is my goal.
>>At the moment the thing is driving a 10k resistor with 351.5V, pulling
>>0.315A from a 45.1V supply, for 87.0% efficiency. I'm running at 150kHz
>> with 40% duty.
> A very quick WAG on those numbers is that Lp= 70uH
> and Ipk= 1.5A, approx.
Hi Tony. Thanks for the reply!
I don't understand why you calculate only 70uH? Are you using some
formula that attempts to deal with the non-linearity of the
permeability? I mean, a first cut is to use the Al value right out of
the book (the Ferroxcube catalog) which is 100 nH/turn^2, so L=Al*N^2=100uH.
Then there would be about 1.2A pk, since I'm running a little lower
frequency than I originally intended.
I'll do more detailed measurements, aimed at improving my undertstanding
later, when I'll probably look for the amount of current that starts
saturating the core. 160mT is pretty conservative.
Christopher R. Carlen
Suse 8.1 Linux 2.4.19