Core loss article

VERY nice logo!

And great writing !

This paper will come in handy.

Keep up the great work !

boB K7IQ

Sorry Tim, but neither browser here can pick it up.

How was it published?

RL

Dowloaded instantly using wget.

Looks good. I'll go away and read it properly, now. Thanks, Tim.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)

Maybe your computer/ISP can't talk to my server? Or maybe it was clogged or down at the moment?

It's just a file on the http directory, nothing special, no scripts or anything.

Tim

--
Deep Friar: a very philosophical monk. 
Website: http://seventransistorlabs.com

legg wrote in news: snipped-for-privacy@4ax.com:

??????? It works perfectly here(firefox/foxit reader on XP-SP3.).

I finally just saved the blank page that was displayed in IE6, as 'Core_Loss.pdf'. This proved to be a working pdf document.

Fiddling with preferences in Seamonkey/firefox, I pointed the application helper for Acrobat(application/pdf) to adobe reader7. This allowed the pdf to open in the browser.

Never had either issue previously. Curious.

Will review, anyways.

RL

He used "Latex with hyperref package" according to the document properties, and pdfTex-1.40.12 to produce the PDF 1.5 file.

What's that Type-3 Adobe font "F58" for? Oh, I see, the bullets on pages 6 and 8.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

It doesn't mind this Firefox under Linux, I just tried it. No problem.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)

It worked for me. XP & Firefox 17.0.1

Joerg probably had problems as well >:-} ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Was't it Joerg who claimed XP ran fine with just 128 MB of RAM?

Joerg has all kinds of problems that no one else has.

I think it's because he's so paranoid.

He's locked his system down to the point that he can't download anything useful.

And everything locks up if he sneezes >:-}

And he's become such a weenie he can't even defend making an obvious change to a TEXT HEADER... sort of indicates he has no clue about simulators and the differences between libraries and symbols.

No point in offering any further help... he'll just whine about why he can't do what is suggested :-( ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Some people need more than one computer. Some of those people refuse to use more than one. there have been times I had five systems running on multiple desks, and had to run from room to room to keep up. It gets too crowded when you have more than two systems on one desk, unless it's

48" * 96". Then you can set up eight computers, four per side. :)

I (sort of) groaned when you adopted MMKS as units. Perhaps you didn't realize that KW/m^3 of common core loss graphs can be read directly as mW/cm^3? Dropped, missing or mistranslated orders of magnitude can play havoc.

Perhaps you should have titled this article Core_Loss_of_Powdered_Toroidal_Inductors? There's nothing wrong with adding information to titles, if it cuts down on the end user's time.

A power loss budget, in preliminary design, is dependant on some major indices; surface area (or thermal impedance to ambient); maximum permitted spot temperature; and the total power loss.

In free air, thermal impedance can be rule of thumbed as somewhere between 0.8 and 1.2 degreesC rise per mW/cm^2 of surface area. A forced air requirement reduces this, but places downstream environmental restrictions and costs on the entire system in which the component is expected to perform.

Saying that a T-68-based inductor might dissipate one or two watts comfortably is not helping your readers make a decision on this point.

Maximum permitted spot rise will either be the margined rating of the materials used, a similar but safety-agency-dominated limit value, or the maximum temperature at which the actual published core loss data remains valid. At the limit temperatures, the core loss characteristic become increasingly positive in temperature coefficient, encouraging thermal runaway. It is seldom characterized or specified for powdered cores, probably for this exact reason; and that it would be extremely discouraging to sales. For ferrites, manufacturers are more forthcoming, as the PTC of loss only starts to kick in above a certain grade-type-specific value, in a bathtub curve. By selecting the material grade, one also selects the intended end-use environment.

Other core material features exhibit temperature dependence and should be reviewed at the design limits intended.

Core loss is an AC phenomena. The Bmax in your formula should probably be deltaB/2, as this corresponds to the peak flux density for sinusoidal data presented by the manufacturer. This correspondence isn't guaranteed, as core loss is noted to vary, the farther it strays from the zero-flux crossing point, into regions approaching saturation. Very poor data from the industry or academia on this.

As the tolerance of core loss can vary by a wide factor within a single material grade, it is unwise to use it as a main limiting factor in any design. Copper losses, which predictably increase logarithmically with increased current, will produce a much more reliable indication of end-use, load-limiting factors in the production of spot temperature limits.

In isolating transformer applications, the amount of copper fill obtained can dominate calculations of through-put power capability for any core shape and topology. Philips/Ferroxcube and Siemens both publish guidelines illustrating expected power transfer through characteristic power core shapes, when used in specific topologies, over the frequency range of specific material grades.

RL

I set up Firefox to open acrobat to read the PDF rather than embed it into the page. This seems to work way better for me. (win xp or 7)

boB

Nice job on writing the paper. I cannot comment on the technical stuff becasue I am trying to absorb it. However,

I would change:

------------ Seven Transistor Labs takes no responsibility for liability, damage or other adverse consequences incurred in the use, handling or operation of its products.....etc

-------------

to :

--------------- the author takes no responsibility for liability, damage or other adverse consequences incurred in the use, handling or operation of its products.....etc

-----------------------

I suspect seven transistor labs does not really exist as any kind of legal entity with property to protect, and since STL is you ( completely , I assume) I would make it explicit that the author assumes no liability. After all, I suspect that protecting the author is more important than protecting a shell entity that has no value. (Of course I could be wrong on this...just food for thought If you want the mumbo jumbo in there)

Weird. Wonder if the mime type is funky or something.

Tim

--
Deep Friar: a very philosophical monk. 
Website: http://seventransistorlabs.com

Ah, good point. It would be nice to have an LLC or something some day, but you're right it's basically me being silly right now. :)

Tim

--
Deep Friar: a very philosophical monk. 
Website: http://seventransistorlabs.com