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Need the topology for a current to current SMPS, not voltage to voltage SMPS

Started by RobertMacy October 16, 2013
"RobertMacy" <robert.a.macy@gmail.com> wrote in message 
news:op.w44cski02cx0wh@ajm...
> On Thu, 17 Oct 2013 11:08:49 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Spehro Pefhany wrote: >>> ..snip... >>> Did he say 60Hz? I could imagine RF here. >>> >> >> Well, that's the difficulty here, Robert can't divulge too much so all >> we can do is take potshots. >> > Actually, go ahead and try at 60Hz.
So, think neon sign transformer, though a bit less in voltage for whatever undisclosed purpose? Tim -- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
On Thursday, October 17, 2013 5:57:16 PM UTC-4, Robert Macy wrote:
> On Thu, 17 Oct 2013 09:26:47 -0700, George Herold <gherold@teachspin.com> > > wrote: > > > > >> ...snip... > > > Whoa! Hey, a big word of caution Robert. I've not built a spms in my
<snip>
> > Doesn't matter about the 'source' of concepts, what matters is that you > 'triggered' inside my brain an approach that almost in a single step does > what I want. ....with a few changes.
Excellent! Carry on then (As my ret. navy friend says.) George H.
On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote:
> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold <gherold@teachspin.com> > wrote: > >>> ...snip... >> OK... We haven't done many AC circuit yet.. but I'm guessing the same >> sort of thing can be done. >> For completeness here's the way a current source buck-boost should look. >> >> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >> (I figured out in the shower that the capacitor was in wrong.) >> >> George H. > > Thanks again for the images, surprisingly this time dropbox let me view > them - usually doesn't. > > IN: AC with source current maybe 30-50mA, compliance to 1kV > OUT: approx 5Vdc, with variable current, adjusted with time envelope from > 0.8A down to 50uA.
current buck-boost converter. +--+-FET--+--|<------- | | === 3|| | 3|| | | +--+------+----------- the more time the switch (FET in the diagram) spends off the larger the current output -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
On 10/19/2013 2:26 AM, Jasen Betts wrote:
> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold <gherold@teachspin.com> >> wrote: >> >>>> ...snip... >>> OK... We haven't done many AC circuit yet.. but I'm guessing the same >>> sort of thing can be done. >>> For completeness here's the way a current source buck-boost should look. >>> >>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>> (I figured out in the shower that the capacitor was in wrong.) >>> >>> George H. >> >> Thanks again for the images, surprisingly this time dropbox let me view >> them - usually doesn't. >> >> IN: AC with source current maybe 30-50mA, compliance to 1kV >> OUT: approx 5Vdc, with variable current, adjusted with time envelope from >> 0.8A down to 50uA. > > current buck-boost converter. > > +--+-FET--+--|<------- > | | > === 3|| > | 3|| > | | > +--+------+----------- > > the more time the switch (FET in the diagram) > spends off the larger the current output >
I don't understand how you can get more current out of the inductor than it had when the switch opened.
John S wrote:
> On 10/19/2013 2:26 AM, Jasen Betts wrote: >> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >>> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold >>> <gherold@teachspin.com> >>> wrote: >>> >>>>> ...snip... >>>> OK... We haven't done many AC circuit yet.. but I'm guessing the same >>>> sort of thing can be done. >>>> For completeness here's the way a current source buck-boost should >>>> look. >>>> >>>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>>> (I figured out in the shower that the capacitor was in wrong.) >>>> >>>> George H. >>> >>> Thanks again for the images, surprisingly this time dropbox let me view >>> them - usually doesn't. >>> >>> IN: AC with source current maybe 30-50mA, compliance to 1kV >>> OUT: approx 5Vdc, with variable current, adjusted with time envelope >>> from >>> 0.8A down to 50uA. >> >> current buck-boost converter. >> >> +--+-FET--+--|<------- >> | | >> === 3|| >> | 3|| >> | | >> +--+------+----------- >> >> the more time the switch (FET in the diagram) >> spends off the larger the current output >> > > I don't understand how you can get more current out of the inductor than > it had when the switch opened.
Ask a politician, they can do that :-) -- SCNR, Joerg http://www.analogconsultants.com/
On 10/19/2013 10:03 AM, Joerg wrote:
> John S wrote: >> On 10/19/2013 2:26 AM, Jasen Betts wrote: >>> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >>>> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold >>>> <gherold@teachspin.com> >>>> wrote: >>>> >>>>>> ...snip... >>>>> OK... We haven't done many AC circuit yet.. but I'm guessing the same >>>>> sort of thing can be done. >>>>> For completeness here's the way a current source buck-boost should >>>>> look. >>>>> >>>>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>>>> (I figured out in the shower that the capacitor was in wrong.) >>>>> >>>>> George H. >>>> >>>> Thanks again for the images, surprisingly this time dropbox let me view >>>> them - usually doesn't. >>>> >>>> IN: AC with source current maybe 30-50mA, compliance to 1kV >>>> OUT: approx 5Vdc, with variable current, adjusted with time envelope >>>> from >>>> 0.8A down to 50uA. >>> >>> current buck-boost converter. >>> >>> +--+-FET--+--|<------- >>> | | >>> === 3|| >>> | 3|| >>> | | >>> +--+------+----------- >>> >>> the more time the switch (FET in the diagram) >>> spends off the larger the current output >>> >> >> I don't understand how you can get more current out of the inductor than >> it had when the switch opened. > > > Ask a politician, they can do that :-) >
So, I should have studied politics rather than engineering. I guess Momma was right.
On Wed, 16 Oct 2013 09:35:10 -0700, RobertMacy
<robert.a.macy@gmail.com> wrote:

>Need a current to current SMPS, with greater than 95% efficiency. and NOT >a transformer! because has to be variable. > >The output will be a 'defined' current-time profile. Output Power is low, >less than 5-10W delivered. Voltage compliance is low, less than 10 Vdc. >I'm having difficulty wrapping my brain around potential topologies, need >some help here. > >Anybody ever do this, or have some URL's with topologies? > >Problem hint: voltage to voltage means unused input power is OPEN, but >current to current means unused power is SHORTED. See the difference?
I don't understand the details of your application, but an ideal switcher with a fixed-power load has a negative input impedance, so will be unstable if driven by a constant-current source. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
John S wrote:
> On 10/19/2013 10:03 AM, Joerg wrote: >> John S wrote: >>> On 10/19/2013 2:26 AM, Jasen Betts wrote: >>>> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >>>>> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold >>>>> <gherold@teachspin.com> >>>>> wrote: >>>>> >>>>>>> ...snip... >>>>>> OK... We haven't done many AC circuit yet.. but I'm guessing the same >>>>>> sort of thing can be done. >>>>>> For completeness here's the way a current source buck-boost should >>>>>> look. >>>>>> >>>>>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>>>>> (I figured out in the shower that the capacitor was in wrong.) >>>>>> >>>>>> George H. >>>>> >>>>> Thanks again for the images, surprisingly this time dropbox let me >>>>> view >>>>> them - usually doesn't. >>>>> >>>>> IN: AC with source current maybe 30-50mA, compliance to 1kV >>>>> OUT: approx 5Vdc, with variable current, adjusted with time envelope >>>>> from >>>>> 0.8A down to 50uA. >>>> >>>> current buck-boost converter. >>>> >>>> +--+-FET--+--|<------- >>>> | | >>>> === 3|| >>>> | 3|| >>>> | | >>>> +--+------+----------- >>>> >>>> the more time the switch (FET in the diagram) >>>> spends off the larger the current output >>>> >>> >>> I don't understand how you can get more current out of the inductor than >>> it had when the switch opened. >> >> >> Ask a politician, they can do that :-) >> > > So, I should have studied politics rather than engineering. I guess > Momma was right.
If you and I had done that we'd be rich. But probably not too happy. If I were 18 again I'd veer towards a brewmaster's degree and keep EE as a hobby. No kidding. -- Regards, Joerg http://www.analogconsultants.com/
On 10/19/2013 1:41 PM, Joerg wrote:
> John S wrote: >> On 10/19/2013 10:03 AM, Joerg wrote: >>> John S wrote: >>>> On 10/19/2013 2:26 AM, Jasen Betts wrote: >>>>> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >>>>>> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold >>>>>> <gherold@teachspin.com> >>>>>> wrote: >>>>>> >>>>>>>> ...snip... >>>>>>> OK... We haven't done many AC circuit yet.. but I'm guessing the same >>>>>>> sort of thing can be done. >>>>>>> For completeness here's the way a current source buck-boost should >>>>>>> look. >>>>>>> >>>>>>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>>>>>> (I figured out in the shower that the capacitor was in wrong.) >>>>>>> >>>>>>> George H. >>>>>> >>>>>> Thanks again for the images, surprisingly this time dropbox let me >>>>>> view >>>>>> them - usually doesn't. >>>>>> >>>>>> IN: AC with source current maybe 30-50mA, compliance to 1kV >>>>>> OUT: approx 5Vdc, with variable current, adjusted with time envelope >>>>>> from >>>>>> 0.8A down to 50uA. >>>>> >>>>> current buck-boost converter. >>>>> >>>>> +--+-FET--+--|<------- >>>>> | | >>>>> === 3|| >>>>> | 3|| >>>>> | | >>>>> +--+------+----------- >>>>> >>>>> the more time the switch (FET in the diagram) >>>>> spends off the larger the current output >>>>> >>>> >>>> I don't understand how you can get more current out of the inductor than >>>> it had when the switch opened. >>> >>> >>> Ask a politician, they can do that :-) >>> >> >> So, I should have studied politics rather than engineering. I guess >> Momma was right. > > > If you and I had done that we'd be rich. But probably not too happy. If > I were 18 again I'd veer towards a brewmaster's degree and keep EE as a > hobby. No kidding. >
It very hard to resist your true calling, I learned.
John S wrote:
> On 10/19/2013 1:41 PM, Joerg wrote: >> John S wrote: >>> On 10/19/2013 10:03 AM, Joerg wrote: >>>> John S wrote: >>>>> On 10/19/2013 2:26 AM, Jasen Betts wrote: >>>>>> On 2013-10-17, RobertMacy <robert.a.macy@gmail.com> wrote: >>>>>>> On Thu, 17 Oct 2013 06:01:01 -0700, George Herold >>>>>>> <gherold@teachspin.com> >>>>>>> wrote: >>>>>>> >>>>>>>>> ...snip... >>>>>>>> OK... We haven't done many AC circuit yet.. but I'm guessing the >>>>>>>> same >>>>>>>> sort of thing can be done. >>>>>>>> For completeness here's the way a current source buck-boost should >>>>>>>> look. >>>>>>>> >>>>>>>> https://www.dropbox.com/s/eey79dkci1sqpp0/DSCF0034.JPG >>>>>>>> (I figured out in the shower that the capacitor was in wrong.) >>>>>>>> >>>>>>>> George H. >>>>>>> >>>>>>> Thanks again for the images, surprisingly this time dropbox let me >>>>>>> view >>>>>>> them - usually doesn't. >>>>>>> >>>>>>> IN: AC with source current maybe 30-50mA, compliance to 1kV >>>>>>> OUT: approx 5Vdc, with variable current, adjusted with time envelope >>>>>>> from >>>>>>> 0.8A down to 50uA. >>>>>> >>>>>> current buck-boost converter. >>>>>> >>>>>> +--+-FET--+--|<------- >>>>>> | | >>>>>> === 3|| >>>>>> | 3|| >>>>>> | | >>>>>> +--+------+----------- >>>>>> >>>>>> the more time the switch (FET in the diagram) >>>>>> spends off the larger the current output >>>>>> >>>>> >>>>> I don't understand how you can get more current out of the inductor >>>>> than >>>>> it had when the switch opened. >>>> >>>> >>>> Ask a politician, they can do that :-) >>>> >>> >>> So, I should have studied politics rather than engineering. I guess >>> Momma was right. >> >> >> If you and I had done that we'd be rich. But probably not too happy. If >> I were 18 again I'd veer towards a brewmaster's degree and keep EE as a >> hobby. No kidding. >> > > It very hard to resist your true calling, I learned.
The problem is to figure out what your true calling is. Some people realize that late in life. For example, a top chemical scientist in our area who some day when he was well in his 50's quit his well-paying job at Monsanto and started a winery. He said he'd found his true calling. Or a sccessful surgeon who, late in his 50's, became a pilot (after an expensive trek through commercial pilot flight schooling) and hired on with an airline. His income probably went down by 10-15dB but he was happy. -- Regards, Joerg http://www.analogconsultants.com/