KerimF
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Once you started a thread in an appropriate forum, you should continue it instead of crossposting the topic in a different place. Your first posts suggests that you have an idea how to measure the said parameters.
I think the measurement method is more or less obvious, you need to run a sufficient range of the B/H curve with a strong AC source and record current and induced voltage. Most digital oscilloscopes can directly display the curve.
Some remarks.
- The Bs, Hc etc. extraction can be better done based on the B/H plot, using integral V(LL), I think.
- Coil series resistance must be zeroed for true flux measurement.
- The coil can be better driven by an AC current source.
- By increasing the drive current of about +/- 4.3A to higher values, you see that your test is considerably below saturation.
- Saturation point is reached when the B/H slope approaches the air coil value (µr = 1). You'll substract delta B(µr=1) to get Bs.
Forgot to mention that extraction of Bs, Br and Hc from B/H curve is described in LTspice online manual. To get correct A/m scaling in the plot, I(L1) has to multiplied with NN/Len = 80.
Right, induced voltage has to be integrated to get B proportional signal. Problem with passive RC circuit is that it has either very low output voltage or large phase error. Better to use an OP amp integrator. As mentioned in post #2, most digital oscilloscopes can directly generate B/H-curve with built-in integrator math function in X/Y mode.
I stumbled upon a comment in an unrelated thread https://www.edaboard.com/threads/q01-–-voltage-to-phase-shift.406471/post-1751846.
It suggests that post #4 proposes a simple and accurate method to measure the core parameters of an unknown core and complains about the ignorance of forum members not honoring it.
I believe that's wrong. Modifying parameters (particularly Vp, also F a bit) produces quite different results. So the least we can say is that the method needs corrections.
I just wonder why it is not clear that we get the same results for the three parameters from plotting the B/H curve and from reading just the 4 special values on v(t) and i(t) and applying their 3 formulas.if acceptance criteria are defined first and then met, then the result is 100% acceptable
Hi,Some remarks.
- The Bs, Hc etc. extraction can be better done based on the B/H plot, using integral V(LL), I think.
- Coil series resistance must be zeroed for true flux measurement.
- The coil can be better driven by an AC current source.
- By increasing the drive current of about +/- 4.3A to higher values, you see that your test is considerably below saturation.
- Saturation point is reached when the B/H slope approaches the air coil value (µr = 1). You'll substract delta B(µr=1) to get Bs.
View attachment 182173 View attachment 182174
--- Updated ---
Forgot to mention that extraction of Bs, Br and Hc from B/H curve is described in LTspice online manual. To get correct A/m scaling in the plot, I(L1) has to multiplied with NN/Len = 80.
View attachment 182176
Hi, Appreciate the post!Some remarks.
- The Bs, Hc etc. extraction can be better done based on the B/H plot, using integral V(LL), I think.
- Coil series resistance must be zeroed for true flux measurement.
- The coil can be better driven by an AC current source.
- By increasing the drive current of about +/- 4.3A to higher values, you see that your test is considerably below saturation.
- Saturation point is reached when the B/H slope approaches the air coil value (µr = 1). You'll substract delta B(µr=1) to get Bs.
View attachment 182173 View attachment 182174
--- Updated ---
Forgot to mention that extraction of Bs, Br and Hc from B/H curve is described in LTspice online manual. To get correct A/m scaling in the plot, I(L1) has to multiplied with NN/Len = 80.
View attachment 182176
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