Epcos do. I've had good results with Epcos cores, using their "Ferrite Magnetics Design Tool", then translating their hysteresis curves into the Chan model, and their loss figures into lumped resistance in parallel. Gets pretty near actual measurements. Works in .tran, no problem.
--
"Design is the reverse of analysis"
(R.D. Middlebrook)
Oops. Just came back, the bill will be painful but not written yet. Because they took me in as an emergency and didn't fire up the server.
1h+ session, the dentist gave me the legal limit for anesthetics, not enough, had to go in anyhow, what else can ya do ... ouch, ouch. But now it's done.
Best dentist we ever had. But he is well into his 70's and when he ever retires I don't know what we are going to do.
Mine usually go directly from simulator to CAD and then to fab. So we get complete proto boards back. On simple designs that's usually it, goes into production like that after testing.
I found that the simulations are darn close to the real-life results later, except you never quite know how hot the core will get. This time it was a bit much but it was a complicated design.
I'm quite pain tolerant, which is a good thing, since most anesthetics don't do much for me. It was first noticed when I had my tonsils out at age 7... they couldn't put me out with Ether... had to use Morphine ;-)
Fortunately, modern anesthetics seem to work OK. I had my left eye lens changed out a few weeks ago... didn't feel a thing.
And I tore a rotator cuff reaching out too far to lift a propane tank a couple of months ago :-( Finally gave up on it healing itself and had an MRI last week... definitely torn, plus some old age degradation :-( They'll patch that orthoscopically. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
I'm pondering that it may be possible to make a subcircuit that will come quite close... without having any complex core model available.
We know that the losses are proportional to the flux change and to the frequency to some power. So maybe a few measurements on a core to get the coefficients, then create a subcircuit that has an extra pin that shows power dissipated. (We'd still have the thermal resistance issue to ponder.)
Most of the switchers I've made are really high power, like 5V/400A, with fist-sized Ferroxcube E-E transformers, or very small... like
12V/20mA for cellphone touch screens.
Cool, in all cases... as I've told about the "cool" one that had 400V P-P on the mounting flag ;-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
As for the simulation of magnetics in PSpice, the magnetics simulation tool allows for advanced simulation of Magnetics and Ferroxcube parts (other th ird party manufactors can be added) including detailed information on bobbi n and even insulation materials. It even has a wizard when creating the mod el the will check against fill factor and guide through the construction of the part if needed.
I know. I was just pondering how to make a more universal tool.
Though some have said there's a "Chan" model in LTspice. Is Joerg overlooking a built-in solution for those who adhere to "free" ?:-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
At a past job, there were a couple of boards that had mods that were unobvious to the naked eye but that made them Different than production. I wrote "Engineering" on the RF shield cans in Sharpie. I may have also written it on the board, too... I wouldn't put it past one manager to swap graffiti-free shield cans onto the board so he could ship it. This board was the size of one of your VME boards, though, and had several
1.5" x 2" or so shield cans. Harder to do on a tiny board.
I threatened to paint the front panels pink, but I never got brave enough to. One of my co-workers liked to run engineering boards without a front panel if he could get away with it.
I have heard of, but not personally seen, somebody soldering a few "mistake" wires onto a board... they went from +5 V to +5 V or ground to ground, but they were allegedly enough to stop the boards from being shipped.
A lot of the early bobbin cores for SMD were/are pressed iron dust, that really weren't meant for large deltaB. This is usually the reason why loss isn't specified. The shapes aren't cheaply obtainable in ferrite.
If the material is recognizable, then yes, core loss is a standard specification.
I'm not a fan of some of the representations made for core loss calculation formulas, but Siemens/Epcos, Philips/Ferroxcube and MagneticsInc are pretty good at coming up with coefficients that correspond to the earlier work of Snelling for ferrites. This is the most common material used in serious HF magnetics experiencing larger AC flux excursions.
Magnetics has tried to extend this to some of the higher flux, lower permeability powder cores, but has yet to present proper ferrite/powder correlation.
A search for "Magnetics-Ferrite-Core-Loss-Equations" will find a spreadsheet that might be of interest.
The "Chan" model in LTSpice only works for isolated inductors - you can't directly couple such an inductor to other inductors to simulate a transformer.
--
Bill Sloman. Sydney (but in Nijmegen at the moment)
Does saturation have a loss mechanism? ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
It is, but that only helps once you know the losses.
I suppose one could go backwards once a particular inductor has been tested (how many watts is 50C temp rise?), assuming AC+DC copper losses can be teased apart. Destructive testing of a part would be informative with regards to winding construction (wire diameter, turns spacing, layers; skin depth, proximity effect; AC/DC resistance ratio), and would also tell number of turns and core area.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://seventransistorlabs.com
I lose semoconductors just trying to get them from the tube onto the PC board.
--
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
Use this .plt file, with the model I already posted, giving losses in the inductor.
Make sure that you set rser=0 l-(
Play with the Chan model constants, you'll find that losses are due to coercivity, rather than saturation. Ignore the Spice artifact spikes (smaller maxstep helps).
Hysteresis loss isn't the whole enchilada, by any means.
I also found a paper by Hermann Haus and Jim Melcher (one of my grad student mentors while I was at MIT) which thoroughly discusses the problem. I'll see if I can't set the math to a behavioral model that will work with all flavors of Spice. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
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