Forums

New Switching Converter Topology?

Started by Tim Williams October 19, 2017
Does this... exist?  I mean, has it been named, or enumerated anywhere?

https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png

Sort of like a Cuk, but swapping the capacitor and switch.  Could be used 
for low ripple buck (drop D1 and Q2), a kind of extended-winding boost 
(change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing 
source/load (note that switching Q1+Q2 is a I/III quadrant operation), 
generating a negative rail (set one supply to zero, and move the diodes to a 
new negative rail), etc.

Tim 

On Thursday, October 19, 2017 at 5:19:10 AM UTC-4, Tim Williams wrote:
> Does this... exist? I mean, has it been named, or enumerated anywhere? > > https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png
Tim, I'm not much of a switcher guy. But I don't see how you get current to flow in in that circuit. The two lines going off the screen are just for fet switching, I assume. George H.
> > Sort of like a Cuk, but swapping the capacitor and switch. Could be used > for low ripple buck (drop D1 and Q2), a kind of extended-winding boost > (change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing > source/load (note that switching Q1+Q2 is a I/III quadrant operation), > generating a negative rail (set one supply to zero, and move the diodes to a > new negative rail), etc. > > Tim
On Thu, 19 Oct 2017 07:18:14 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Thursday, October 19, 2017 at 5:19:10 AM UTC-4, Tim Williams wrote: >> Does this... exist? I mean, has it been named, or enumerated anywhere? >> >> https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png >Tim, I'm not much of a switcher guy. But I don't see how you get current to >flow in in that circuit. The two lines going off the screen are just >for fet switching, I assume. > >George H. >>
Another of Tim's wet dreams. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.
On Thu, 19 Oct 2017 04:19:02 -0500, "Tim Williams"
<tmoranwms@gmail.com> wrote:

>Does this... exist? I mean, has it been named, or enumerated anywhere? > >https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png > >Sort of like a Cuk, but swapping the capacitor and switch. Could be used >for low ripple buck (drop D1 and Q2), a kind of extended-winding boost >(change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing >source/load (note that switching Q1+Q2 is a I/III quadrant operation), >generating a negative rail (set one supply to zero, and move the diodes to a >new negative rail), etc. > >Tim
If the switches were reverse polarity, it would be a DC fransformer with fixed voltage ratios. As is, it does nothing. Swapping things means thatr they're still present. There's no capacitor in your drawing. RL
Normally I am open to new topologies, just not any with the &lsquo;novel&rsquo; in the title 

But I cannot really see the point of your topology

Cuk is famous for talking wonders about his in his words superior topology, but I have never heard of anyone using it and never seen a case where it would be close to come into consideration 

To understand your topology, can you name a case in which it outperforms any current topology?

Cheers

Klaus
On Thu, 19 Oct 2017 12:21:47 -0700 (PDT), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>Normally I am open to new topologies, just not any with the &#2013266065;novel&#2013266066; in the title > >But I cannot really see the point of your topology > >Cuk is famous for talking wonders about his in his words superior topology, but I have never heard of anyone using it and never seen a case where it would be close to come into consideration
We use the coupled Cuk topology in several of our products. It has some nice features. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
"George Herold" <gherold@teachspin.com> wrote in message 
news:97f04761-9b2c-4c6e-9cb6-90369076eb61@googlegroups.com...
>> https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png > Tim, I'm not much of a switcher guy. But I don't see how you get current > to > flow in in that circuit. The two lines going off the screen are just > for fet switching, I assume. >
When the transistors turn on, the inductors are connected in series, and current ramps at dI/dt = (V1 - V2) / 4L (taking L as primary inductance and the windings 1:1). When off, the inductors flyback, and one is clamped with a diode, so the inductor voltage is -min(V1, V2) until fully discharged or the transistors turn on again. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
"Klaus Kragelund" <klauskvik@hotmail.com> wrote in message 
news:82eb67ba-e83c-4105-b7bc-432d4803599d@googlegroups.com...
>Normally I am open to new topologies, just not any with the &lsquo;novel&rsquo; in >the title >
But I didn't put "novel" in the title. (Fine, "new" is the same meaning, different root, so what. :^) ) I'm expecting it's been done before, and that's what I want to know. :)
> But I cannot really see the point of your topology > .. >To understand your topology, can you name a case in which it outperforms >any current topology? >
Anywhere you want a buck, that bucks in either current direction (whereas a synchronous buck is boost in reverse), where the source and load may be swapped freely (V2 > V1 or vice versa), and you don't need voltage boosting capability (where you'd need SEPIC or such). Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
On 2017-10-19 02:19, Tim Williams wrote:
> Does this... exist? I mean, has it been named, or enumerated anywhere? > > https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png > > Sort of like a Cuk, but swapping the capacitor and switch. Could be > used for low ripple buck (drop D1 and Q2), a kind of extended-winding > boost (change D1 to transistor, Q2 to diode, drop Q1 and D2), equalizing > source/load (note that switching Q1+Q2 is a I/III quadrant operation), > generating a negative rail (set one supply to zero, and move the diodes > to a new negative rail), etc. >
Bidirectional flybacks, forwards and others exist: https://repository.tudelft.nl/islandora/object/uuid:3b6463db-cb3f-42ce-9caf-6835bce95f5a/datastream/OBJ/download They can be practical with systems that need a higher degree of failure safety where either side can feed the other if it fails, but otherwise remain electrically separated. Also for supercap storage or electric vehicles that are supposed to act as storage devices when needed. -- Regards, Joerg http://www.analogconsultants.com/
On Thu, 19 Oct 2017 14:54:49 -0500, "Tim Williams"
<tmoranwms@gmail.com> wrote:

>"George Herold" <gherold@teachspin.com> wrote in message >news:97f04761-9b2c-4c6e-9cb6-90369076eb61@googlegroups.com... >>> https://www.seventransistorlabs.com/Images/Bidirectional_Buck.png >> Tim, I'm not much of a switcher guy. But I don't see how you get current >> to >> flow in in that circuit. The two lines going off the screen are just >> for fet switching, I assume. >> > >When the transistors turn on, the inductors are connected in series, and >current ramps at dI/dt = (V1 - V2) / 4L (taking L as primary inductance and >the windings 1:1). When off, the inductors flyback, and one is clamped with >a diode, so the inductor voltage is -min(V1, V2) until fully discharged or >the transistors turn on again. > >Tim
Here's my first switching regulator design: https://www.dropbox.com/s/00d953dslj797yu/Old_Switcher.JPG?dl=0 Power schottky diodes were just becoming available from Motorola, and I could only get 20 volt parts, so I hung the catch diode on the inductor center-tap. But N*I is preserved, and N changes by 2:1 when it switches, so the ripple current is big and sharp into the output cap. It worked, but the wet-slug tantalum got warm. I think your circuit has similar high output ripple current. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com