Magnetic permeability

[Pixelx]

Hi,

In my free time I research magnetic materials. I can determine magnetic hysteresis loops and the core magnetization curve.
The loop I designate is practically the same as in the core documentation.
I have a problem with various formulas and possibilities of determining magnetic permeability.

1. Why are there no characteristics of the relative permeability of magnetic ur from B?
There is a characteristic ua from Bmax.
I determined the magnetization curve from the RMS voltage and RMS current and from the formula B = uo ur H I determined ur and I obtained the same characteristics as the manufacturer ua from Bmax. Is this equivalent?

2. Can I determine ui (initial permability) using the inductance formula? The manufacturer states that at H -->0, I don't really know how to do it based on my data. And will I get the same result as from the inductance formula?
From the formula for inductance, ur is treated as ui and the total result is obtained at H-->0. The measurement with the meter does not produce a large H field. And the result is consistent with what the manufacturer provides.

3. How to determine this urev? Would I have to somehow feed DC current to the transformer? To determine urev from H, does it mean to determine it from Hdc? Is it possible to supply Hdc through another winding and supply AC to the other winding and draw BH loops from the data. But how to calculate lim numerically? Calculate the difference between each sample for H and B?

 

[cupoftea]

Hi,
I take it you are dealing with "non linear inductors" whereby the inductance actually changes with the current....or rather, the permeability changes with the current,
if I speak more correctly.

So, You mean you want to calc L for any current in say a torroid inductor?

The Mag Inc website gives the formulas for you to do it. I attach
my working here. They give you a formula for %u. That's the percentage
of ui. So they give %u vs H for each ferrite mix...then you just work from that.
Do it by discrete integration.
Ie, start I at zero and step it up in say 100mA intervals....calc the new B
for every current level...via uo.ur.H.
Calc the reluctance for every new ur with L = N^2/reluctance
where reluctance = length/uo.ur.A

Calc the new B and find the amount by which B increased for each new step....then add up all those B's at the end to find the total B at whatever inductor current.

The attached shows the calc for the torroid using MP220205-2 Ferrite torroid.

So basically, use discrete integration.....step the current and sum up those B's.