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Scott Deuty

Hysteretic Control: An old technology makes a comeback

Scott Deuty
D Feucht
D Feucht
8/2/2018 1:02:40 PM
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Re: Hysteretic Converter Control
"... a truly archaic technology or computing language turns out to have more to it than meets the eye"

The language is Forth. Those of us who have been using it find it in a bigger league than C or other fixed-definition languages. And it easily fits into 16 kbytes, including interpreter and incremental compiler.

In my previous comment, I forgot to mention that the control subsystem of the "Volksinverter" that I am designing has its own control supply which has a hysteretic controller. I did not find in the available literature any design formulas for it, so if you want it done right ...

I will include the design formulas in the forthcoming inverter articles. (Maybe Scott will beat me to it!) The interesting one calculates the frequency, and it comes out about right as measured in a prototype unit.

 

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PaulChau
PaulChau
6/19/2018 10:20:27 PM
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Re: Hysteretic Converter Control
There is a lot of potential in this world right now that remains totally untapped. I am really not going to be surprised if one day a truly archaic technology or computing language turns out to have more to it than meets the eye. Sounds a bit like a plot of a movie, but it could really turn out to be that way - all it takes is for someone to be able to come along and unlock more features to all these things that we've once thought had no more secrets to spill...

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Effective-Technical-Writing dot com
Effective-Technical-Writing dot com
6/19/2018 7:42:06 PM
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Re: Hysteretic Converter Control
Thanks D,

I am reverse engineering a similar design that's in a "deterrent".  The more I look into the hysteretic control, the more I realize that there isn't much written about this interesting technology.  Anything that you can contribute will surely provide more insight.  Work with our editor Steven on this contribution.  By the way I can't pull up the article while responding to see if I mentioned a bang bang converter however this is the bang bang converter technology.  

Scott

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steve.taranovich
steve.taranovich
6/14/2018 7:34:56 PM
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Re: Hysteretic Converter Control
Many thanks for your insights Dennis. We look forward to hearing more about this project

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D Feucht
D Feucht
6/13/2018 10:32:55 PM
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Re: Hysteretic Converter Control
Steve,

I live on a jungle hilltop, miles from a paved road or utilities. Consequently, the inverter is of direct interest. I cannot bring myself (like my non-engineer fellow neighbor homesteaders) to buy an expensive "boat anchor" inverter with 60 Hz magnetics. The low-cost Asian imports cut corners in the design and are unreliable. A Swiss company has a good though expensive unit with too many bells and  whistles - and remote support. Some American brands are okay, but the real problem is maintenance. When it breaks, you must reverse engineer the ciruit to know what it is, to fix it. So if you want it done right ...

This open-source inverter design is well along and is unlike any other I have seen in that it optimizes the battery converter, using a boost-push-pull circuit. The input inductor is an added magnetic component but it also prevents high di/dt that destroys MOSFETs in other designs. It also has a novel overcurrent protection circuit. The prototype design is all through-hole (though need not be manufactured as such), modular, scalable, and uses commodity parts available from multiple suppliers. The only custom parts are the circuit-board (mfg files to be made available) and the magnetic  components, which are constructed of low-cost cores in a way that does not require a winding machine or any specialized equipment (other than a variable-speed drill).

I should have something to present by this fall, I am hoping. I have been working, off and on, on this project for years and it is time to end it! I need a back-up inverter! It can be the source of multiple articles.

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steve.taranovich
steve.taranovich
6/13/2018 12:12:20 PM
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Re: Hysteretic Converter Control
Hi Dennis,

I would love an article on the "Volks-inverter" for off-grid residential use---we could use that on EDN. Would this be something that you would use in your remote location in the 'Boondocks" (Originally meaning a mountain)?

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D Feucht
D Feucht
6/12/2018 4:40:59 PM
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Hysteretic Converter Control
Scott,

I share your interest in the return of hysteretic control of converters, but I don't think loop compensation need be as complicated as Maniktala makes it out to be. I am presently designing a "Volks-inverter" for off-grid residential use and the control subsystem has a hysteretic supply. (I wish I could post it to you.) It has no loop compensation circuitry because these supplies are inherently unstable.

However, what is nontrivial is the design for a given frequency range, and that takes some derivations resulting in design formulas that don't go well in text responses. The equations are needed to determine the inductor value, for instance. Perhaps I'll write an article with it all in the future, inspired by your article.

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