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Inductance modeling using table issue.

 

Hi!
I try to model an inductor using table.
When i simulate this inductor, inductance value initially is changed according to the table that i include, but close to end off table inductance value didn't respect value from table.
I try to change simulation time, and this make a negative effect on inductance (i don't know why!).
Can someone help me with this?

blob:/29cb438c-88fc-4eab-81d2-06d860dc8640
this is how inductance need to be changed with bias current.

blob:/906f8161-46e1-4558-a50a-630d24f881b5? ? ?-- Circuit
blob:/c5224e18-4379-40dd-b2de-90c8572811c4? ?-- Simulation result
?
Text in InductorTable.txt:
B1 tb 0 V = Table(I(V2), -70, 30u, -50.24, 30u, -49.75, 32u, -48.48, 37u, -46.35, 42u, -43.83, 45u, -41.60, 50u, -39.46, 57u, -37.51, 63u, -35.57, 69u, -33.52, 79u, -31.57, 86u, -29.52, 96u, ?-27.67, 107u, -26.10, 119u, -24.54, 127u, -23.26, 138u, -21.79, 149u, -20.13, 162u, -18.95, 173u, -17.67, 184u, -16.69, 195u, -15.50, 208u, -14.13, 222u, -12.94, 237u, ?-11.76, 250u, -10.67, 263u, -9.39, 276u, -8.20, 292u, -7.02, 305u, -6.13, 318u, -5.04, 330u, -3.86, 344u, -2.88, 351u, -1.80, 357u, -0.83, 362u, 0, 364u, 0.83, 362u, 1.80, 357u, 2.88, 351u, 3.86, 344u, 5.04, 330u, 6.13, 318u, ?7.02, 305u, 8.20, 292u, 9.39, 276u, 10.67, 263u, 11.76, 250u, 12.94, 237u, 14.13, 222u, 15.50, 208u, 16.69, 195u, 17.67, 184u, 18.95, 173u, 20.13, 162u, 21.79, 149u, 23.26, 138u, 24.54, 127u, 26.10, 119u, 27.67, 107u, 29.52, 96u, 31.57, 86u, 33.52, 79u, 35.57, 69u, 37.51, 63u, 39.46, 57u, 41.60, 50u, 43.83, 45u, 46.35, 42u, 48.48, 37u, 49.75, 32u, 50.24, 30u, 70, 30u)



My question is: Why inductance value didn't respect the table ?
Thanks for your help ?
?
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?
?
?
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¿ªÔÆÌåÓý

None of your links (blobs???) work. They all return 404 - Page not found.

?Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files or pictures,? in a ZIP archive to Files => Temp.

Go to the web page: /g/LTspice/topics. Click on Files in the list on the left. Then click on Temp. Then click on New Upload in the blue box at top left. Click on Upload File in the drop-down menu. Then send a message to tell us that you did that.

On 2025-03-27 14:14, Tintari Dumitru via groups.io wrote:
Hi!
I try to model an inductor using table.
When i simulate this inductor, inductance value initially is changed according to the table that i include, but close to end off table inductance value didn't respect value from table.
I try to change simulation time, and this make a negative effect on inductance (i don't know why!).
Can someone help me with this?
this is how inductance need to be changed with bias current.
?
Text in InductorTable.txt:
B1 tb 0 V = Table(I(V2), -70, 30u, -50.24, 30u, -49.75, 32u, -48.48, 37u, -46.35, 42u, -43.83, 45u, -41.60, 50u, -39.46, 57u, -37.51, 63u, -35.57, 69u, -33.52, 79u, -31.57, 86u, -29.52, 96u, ?-27.67, 107u, -26.10, 119u, -24.54, 127u, -23.26, 138u, -21.79, 149u, -20.13, 162u, -18.95, 173u, -17.67, 184u, -16.69, 195u, -15.50, 208u, -14.13, 222u, -12.94, 237u, ?-11.76, 250u, -10.67, 263u, -9.39, 276u, -8.20, 292u, -7.02, 305u, -6.13, 318u, -5.04, 330u, -3.86, 344u, -2.88, 351u, -1.80, 357u, -0.83, 362u, 0, 364u, 0.83, 362u, 1.80, 357u, 2.88, 351u, 3.86, 344u, 5.04, 330u, 6.13, 318u, ?7.02, 305u, 8.20, 292u, 9.39, 276u, 10.67, 263u, 11.76, 250u, 12.94, 237u, 14.13, 222u, 15.50, 208u, 16.69, 195u, 17.67, 184u, 18.95, 173u, 20.13, 162u, 21.79, 149u, 23.26, 138u, 24.54, 127u, 26.10, 119u, 27.67, 107u, 29.52, 96u, 31.57, 86u, 33.52, 79u, 35.57, 69u, 37.51, 63u, 39.46, 57u, 41.60, 50u, 43.83, 45u, 46.35, 42u, 48.48, 37u, 49.75, 32u, 50.24, 30u, 70, 30u)



My question is: Why inductance value didn't respect the table ?
Thanks for your help ?
?
?
?
?
?
?
?
--
OOO - Own Opinions only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion

Virus-free.
 

On Thu, Mar 27, 2025 at 10:43 AM, Tintari Dumitru wrote:
My question is: Why inductance value didn't respect the table ?
Since you did not upload a schematic, it is really hard to tell.
?
It is possible that your line with the table is too long.? Did you enter the line (the one starting with B1) as a SPICE Directive (SPICE Netlist)?? Or was it a Bv-symbol with the table's data entered in the Value, Value2, SpiceLine, and SpiceLine2 lines?? I am aware of (I think) a 255 character limit when going from LTspice symbols to Netlist code, which is caused by a Microsoft Windows limit.
?
If the line was in Netlist code or SPICE Directive, was there any line-wrap in the editor you used?
?
Can you diagnose the circuit yourself?? Does the B-source correctly map the input current I(V2) to the voltage V(tb)?
?
Did you correctly implement the behavioral inductance with the FLUX=... formula?? How did you determine the effective inductance as a function of time?? (I'm assuming from your question that this was not an .AC simulation.)
?
Andy
?
 

FYI -
?
I replicated your table() function by copy-and-paste, and it works correctly, as far as I can see.
?
So if a problem remains, it is not in the table() function; it must be something else in your circuit.
?
The odd behavior you mentioned versus time suggests that you might not have used a proper behavioral inductor.? Doing it wrongly leads to wrong results.
?
Andy
 

Always good to see examples and I know know more about tables. I was idly playing with your data and whilst not really relevant to the discussion here but if you paste your data into Excel, graph it and "add a trendline" you can get very very vlose to your data with
?
y = -3E-07x6 + 6E-05x5 - 0.005x4 + 0.1689x3 - 2.2061x2 + 16.023x + 4.6329
(R? = 0.9954)
?
8-)
Ian
(Retired people have too much time on their hands)
 

My last message didn't format very well, too early in the morning...obviously it is a sixth order polynomial, x6 means x**6 etc
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