toroidal core for high current
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From: Jenkins on 19 Jul 2010 13:22 Guys, it should be obvious it was 50khz and not 50Mhz, I made a mistake when I was entering the data to paste it in. Volts In 250 V Volts Out 25 V Load Current 100 A Freq. 50 KHz Vripple 0.25 V Duty Cycle 10 % Ipp Inductor 1 A Ipk Inductor 100.5 A Irms 99.500418759588 A L 450 uH C 800 uF
From: Tim Wescott on 19 Jul 2010 14:12 On 07/19/2010 10:22 AM, Jenkins wrote: > Guys, it should be obvious it was 50khz and not 50Mhz, I made a > mistake when I was entering the data to paste it in. > > Volts In 250 V > Volts Out 25 V > Load Current 100 A > Freq. 50 KHz > Vripple 0.25 V > Duty Cycle 10 % > Ipp Inductor 1 A > Ipk Inductor 100.5 A > Irms 99.500418759588 A > L 450 uH > C 800 uF And look! The inductor value has changed! Regardless, going from 250V to 25V means that the output stage will only be on for 10% of the time, which is putting severe demands on an already heavily used inductor. Why don't you want to use a transformer? -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: Jenkins on 19 Jul 2010 15:01 On Jul 19, 1:12 pm, Tim Wescott <t...(a)seemywebsite.com> wrote: > On 07/19/2010 10:22 AM, Jenkins wrote: > > > Guys, it should be obvious it was 50khz and not 50Mhz, I made a > > mistake when I was entering the data to paste it in. > > > Volts In 250 V > > Volts Out 25 V > > Load Current 100 A > > Freq. 50 KHz > > Vripple 0.25 V > > Duty Cycle 10 % > > Ipp Inductor 1 A > > Ipk Inductor 100.5 A > > Irms 99.500418759588 A > > L 450 uH > > C 800 uF > > And look! The inductor value has changed! duh! Did I say they wouldn't? Just curious... have you ever made a mistake in your life? I made a mistake entering the data... get over it. It's not the end of the world. > Regardless, going from 250V to 25V means that the output stage will only > be on for 10% of the time, which is putting severe demands on an already > heavily used inductor. Why don't you want to use a transformer? I thought the whole point of smps was reduce the transformer size?
From: Tim Wescott on 19 Jul 2010 16:23 On 07/19/2010 12:01 PM, Jenkins wrote: > On Jul 19, 1:12 pm, Tim Wescott<t...(a)seemywebsite.com> wrote: >> On 07/19/2010 10:22 AM, Jenkins wrote: >> >>> Guys, it should be obvious it was 50khz and not 50Mhz, I made a >>> mistake when I was entering the data to paste it in. >> >>> Volts In 250 V >>> Volts Out 25 V >>> Load Current 100 A >>> Freq. 50 KHz >>> Vripple 0.25 V >>> Duty Cycle 10 % >>> Ipp Inductor 1 A >>> Ipk Inductor 100.5 A >>> Irms 99.500418759588 A >>> L 450 uH >>> C 800 uF >> >> And look! The inductor value has changed! > > duh! Did I say they wouldn't? Just curious... have you ever made a > mistake in your life? I made a mistake entering the data... get over > it. It's not the end of the world. I wasn't criticizing; forgive me if it came across that way. And I do make mistakes -- sometimes I think I've screwed up when I haven't :-). >> Regardless, going from 250V to 25V means that the output stage will only >> be on for 10% of the time, which is putting severe demands on an already >> heavily used inductor. Why don't you want to use a transformer? > > I thought the whole point of smps was reduce the transformer size? When I and others say "why don't you use a transformer", we mean "why don't you use a switching regulator topology with a transformer". If you use a transformer with a turns ratio sufficiently less than 10:1 to insure 5V out when the input is at it's lowest ebb then you will minimize the amount of energy that must be stored in the magnetics, and hence their size. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: legg on 19 Jul 2010 20:50
On Mon, 19 Jul 2010 10:21:52 -0700 (PDT), Jenkins <phreon111(a)gmail.com> wrote: >On Jul 19, 8:34�am, "Tim Williams" <tmoran...(a)charter.net> wrote: >> "Jenkins" <phreon...(a)gmail.com> wrote in messagenews:45a92d0d-d2a1-451f-93f3-62c9bee710c9(a)q22g2000yqm.googlegroups.com... >> > How physically large does a toroidal core need to be to handle a 100A >> > smps buck or flyback configuration? <snip> >> >> > Volts In 250 V >> > Volts Out 25 V >> > Vripple 0.25 V >> > Load Current 100 A >> > Freq. 50000 KHz >> >> 50MHz? <snip> > >That should be 50khz and not 50Mhz. L = 450uH... still seems >relatively small. It is four orders of magnitude greater than your previous effort, and your main source of error, here. 1% ripple in a single stage filter may be impractical. A 25V filter inductor will exhibit signifigant core loss and a 100A winding on same will not be simple to achieve. If the solution is as 'small' as you think, you'll be a lucky guy. RL |