StrayLoad loss model in MSL.Electrical.Machines, speeds that cross zeros

[markusandres3DS]

Model:

Modelica.Electrical.Machines.Losses.InductionMachines.StrayLoad

Problem descritpion:

Picking a parameter "power_w" that is not a full number (in my case I chose 0.4) gives problems when the speed is going through zero during simulation.

Possible fix:

A possible fix seems to be the addition of a noEvent additionally to the smooth operator. Could be e.g. the following:

if (strayLoadParameters.PRef <= 0) then
tau = 0;
else
tau = -strayLoadParameters.tauRef*(iRMS/strayLoadParameters.IRef)^2*
smooth(1, noEvent(if w >= 0) then +(+w/strayLoadParameters.wRef)^strayLoadParameters.power_w
else -(-w/strayLoadParameters.wRef)^strayLoadParameters.power_w);
end if;

The combination of smooth + noEvent can be discussed of course, but as a proof-of-concept it seems to work fine for me.

[AHaumer]

To be honest, after looking into that I'm unsure about the smooth ...
I think we should replace the noEvent by abs (which triggers no event!), i.e.
tau = -strayLoadParameters.tauRef*(iRMS/strayLoadParameters.IRef)^2*
(abs(w)/strayLoadParameters.wRef)^strayLoadParameters.power_w

[AHaumer]

The stray load loss model and the permanent magnet loss model should have the same issue:
Modelica.Electrical.Machines.Losses.InductionMachines.StrayLoad
Modelica.Electrical.Machines.Losses.InductionMachines.PermanentMagnetLosses
Modelica.Electrical.Machines.Losses.DCMachines.StrayLoad
Modelica.Magnetic.QuasiStatic.FundamentalWave.Losses.StrayLoad
Modelica.Magnetic.QuasiStatic.FundamentalWave.Losses.PermanentMagnetLosses
We should add an example for testing to ModelicaTest and then test the new implementation comparing it with respect to the old implementation.

[AHaumer]

resolved by SHA-1: f8c9490 for maint/3.2.2
resolved by SHA-1: 2d0c141 for master

[markusandres3DS]

As abs() results in the same as a noEvent() for that case, it seems to be an equally good solution to me.