Hysteresis37

[HansOlsson]

This clears up the unit-issues in the Hysteresis models.

Facts about the PR:

• [x] Unit-consistent
• [x] Without unit-casts
• [ ] Are the new unit strings correct? I don't know; it's possible - even likely, but I haven't seen the original model.

It requires more than Modelica Language 3.6, due to the odd units.

[christiankral]

I understand that the proposed change of units somehow leads to a consistent set of units:

• I do not understand the physical meaning of the parameters P1...P4 with their unit $\sqrt{\mathrm T}$ and of the parameter r with its unit $\sqrt{\frac{1}{\mathrm T}}$. Parameters with such weird units are usually related with emperic "numeric value equations".
• Yet, if unit consistency requires such weird units, it shall be fine with me.
• The term (1-mat.r), however, does not make sense to me at all, as the 1 has to have the same unit as r to make this calculation unit consistent.

[HansOlsson]

• The term (1-mat.r), however, does not make sense to me at all, as the 1 has to have the same unit as r to make this calculation unit consistent.

True, that would imply mat.r.unit="1".

The derivation of the unit for P1...P4 was independent of that; so then the conclusion is then that P1.unit="T(1/2)", mat.r.unit="1", and mat.M.unit="T(1/2)" (since P1=mat.M*mat.r); and the eps-binding in GenericHystTellinenEverett is just broken. Note that this complete fixes Modelica.Magnetic.FluxTubes.Shapes.HysteresisAndMagnets.GenericHystPreisachEverett; where eps is just a fixed constant.

Someone really need to look up the original models - to me the most likely way to solve that is that the eps-binding equation is wrong in some way; likely that it seemed logical to relate the eps to mat.M and it wasn't considered in detail.

Also note that (1-mat.r) will change sign if mat.r passes through 1, and Modelica.Magnetic.FluxTubes.Material.HysteresisEverettParameter.Vacodur50 has mat.r>1; I don't know the significance of that.

[christiankral]

Someone really need to look up the original models - to me the most likely way to solve that is that the eps-binding equation is wrong in some way; likely that it seemed logical to relate the eps to mat.M and it wasn't considered in detail.

I would guess the quantity eps is solely used to numericall stabilize the model. Most likely, there is no physical reason to have it.

[HansOlsson]

Someone really need to look up the original models - to me the most likely way to solve that is that the eps-binding equation is wrong in some way; likely that it seemed logical to relate the eps to mat.M and it wasn't considered in detail.

I would guess the quantity eps is solely used to numericall stabilize the model. Most likely, there is no physical reason to have it.

Seems that way; I tried some simple experiment, and it seemed the result was fairly unchanged even if eps was changed by an order of magnitude.

[HansOlsson]

I have now updated to mat.r.unit="1" and changed eps to a unit-consistent value.