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  1. Duncanampspsud
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Swinging chokes

 

Hello Duncan (and everyone else),

great tool this PSUD2 - I have been using it for years.? ?Thanks for making it free!

I have a query about swinging chokes.? ?One of the webpages (I think its home) you say:
"Filter configurations: Simple C filter, C/R/C, C/L/C and LC (swinging choke)."

Then in the Help pages, under "Program Limitations" - "Inductance" - it says:
"The value of the inductor used in choke power supplies does not vary with DC current, all simulations use a static value. In a real world scenario, the value of the inductor would decrease as the current is increased."

I can't find any way of making a choke "swinging" - so I presume this is a feature not yet available - but your intention is to add it at some point?

thanks

Richard
 

Hi Richard,

It would certainly be possible to put something in, however making it suitable for public consumption would be a whole different story. Putting in a series of parameters to show the inductance variation with current takes it way outside the easy to use simple designer application. I'd consider a different tool for this purpose.

For something like this (and I appreciate there is a need), I've used Magnetics Designer with SPICE software before. A link to the product is ->?

Regards,
Duncan
 

Thanks Duncan.??

Firstly I was merely pointing out the apparent contradiction on your Web pages, which you might want to correct.? And I wasn't sure if I was just not looking in the right place for swinging chokes....

Agreed about the extra complexity in the man/machine interface,? which might be unwelcome for some users.? However there is a further problem, which i have just discovered having been simulating a swinging choke supply using PSUD2.? Its a bit of a faff having to change the inductance for each change of load, but it is at least doable.

The difficulty I found is that data for swinging chokes does not appear to be available beyond two values of current and inductance.?? For instance,? 20/200mA, 20/5H.? The question then arises....what does the curve look like in between those two points?? Is it linear?? If not what is it?

I did a lot of Google searches, and turned up zilch.?? Modelling these chokes will be impossible without that data.

Plainly if you have a choke in your hands, you can, in principle,? measure the curve,? though the test rig could be tricky. But I want to design a supply before I go looking for parts.....

Richard

Get
On 12 Nov 2020, at 10:00, Duncan Munro <duncan@...> wrote:

Hi Richard,

It would certainly be possible to put something in, however making it suitable for public consumption would be a whole different story. Putting in a series of parameters to show the inductance variation with current takes it way outside the easy to use simple designer application. I'd consider a different tool for this purpose.

For something like this (and I appreciate there is a need), I've used Magnetics Designer with SPICE software before. A link to the product is ->?

Regards,
Duncan

 

Hi Richard,

The curve isn't linear, but that's not even the worst part of the problem. As the choke core magnetises, there is some residual field which results in a different curve as the current is coming down again.

There are a few references out there, however this looks like a good page to get an idea of the issue ->?

If you have a look through that, you'll see why I've always been reluctant to pursue anything more than an idealised inductor.

Regards,
Duncan

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