Resolves the problems with zero system (#4654)

[AHaumer]

Implementing a Boolean parameter useZeroSystem to be able to suppress the calculation of the zero current (set to zero).
Backwards compatible: Default = true. In 3 examples (Modelica.Electrical.Machines.Examples.InductionMachines.IMC_YD, Modelica.Magnetic.FundamentalWave.Examples.BasicMachines.InductionMachines.IMC_YD, Modelica.QuasiStatic.Magnetic.FundamentalWave.Examples.BasicMachines.InductionMachines.IMC_YD) used to resolve numerical issues as reported in #4654 and #4486. Setting the attribute nominal = 10 (#4486) has been removed again.
Should we backport this to maintenance/4.1.0 ?

[christiankral]

We shall also add a link to Modelica.Magnetic.FundamentalWave.UsersGuide.ZeroSystem in the documentation of the zero impedance models.

[AHaumer]

@christiankral I followed your suggestions, but the description of the Boolean parameter should rather be:
parameter Boolean useZeroSystem=true "Suppresses zero current, if false";

[christiankral]

@christiankral I followed your suggestions, but the description of the Boolean parameter should rather be: parameter Boolean useZeroSystem=true "Suppresses zero current, if false";

Good point.

[HansOlsson]

quick comment: is there a good reason to call the new model ZeroImpedance when the previous (somewhat related) was called ZeroInductor? I do understand that there's a bit of difference between the two.

[AHaumer]

quick comment: is there a good reason to call the new model ZeroImpedance when the previous (somewhat related) was called ZeroInductor? I do understand that there's a bit of difference between the two.

First: everything is 100% backwards compatible.
@HansOlsson to explain my intention:
The new component is named ZeroImpedance because in reaility it is rather an impedance (with ohmic part) than a pure inductance. Thus - if necessary - it can be enhanced in future easily under the same name.

[casella]

@AHaumer according to Modelica.UsersGuide.Conventions.ModelicaCode.Format, we should have something like

Boolean useZeroSystem=true "= true if zero current is explicitly computed";

[AHaumer]

Now I've corrected descriptions string of useZeroSystem according to Conventions.
@casella should we backport this to maintenance/4.1.0 ?
BTW the maintenance branch is still named 4.1.x, shouldn't it be named 4.1.0?

[HansOlsson]

Looks good, but might add annotation(Evaluate=true); to the parameter as it normally should be evaluated.

[HansOlsson]

LGTM