model StrayLoad "Model of stray load losses dependent on current and speed"
import Modelica.Electrical.MultiPhase.Functions.quasiRMS;
extends Modelica.Electrical.MultiPhase.Interfaces.OnePort;
extends Machines.Interfaces.FlangeSupport;
parameter Machines.Losses.StrayLoadParameters strayLoadParameters "Stray load loss parameters";
extends Modelica.Thermal.HeatTransfer.Interfaces.PartialElementaryConditionalHeatPortWithoutT(useHeatPort = false);
Modelica.SIunits.Current iRMS = quasiRMS(i);
equation
if strayLoadParameters.PRef <= 0 then
tau = 0;
else
tau = -strayLoadParameters.tauRef * (iRMS / strayLoadParameters.IRef) ^ 2 * sign(w) * (abs(w) / strayLoadParameters.wRef) ^ strayLoadParameters.power_w;
end if;
v = zeros(m);
lossPower = -tau * w;
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Documentation(info = "<html>\n<p>\nStray load losses are modeled similar to standards EN 60034-2 and IEEE 112, i.e., they are dependent on square of current,\nbut without scaling them to zero at no-load current.\n</p>\n<p>\nFor an estimation of dependency on varying angular velocity see:<br>\nW. Lang, Über die Bemessung verlustarmer Asynchronmotoren mit Käfigläufer für Pulsumrichterspeisung,\nDoctoral Thesis, Technical University of Vienna, 1984.\n</p>\n<p>\nThe stray load losses are modeled such way that they do not cause a voltage drop in the electric circuit.\nInstead, the dissipated losses are considered through an equivalent braking torque at the shaft.\n</p>\n<p>\nThe stray load loss torque is\n</p>\n<pre>\n tau = PRef/wRef * (i/IRef)^2 * (w/wRef)^power_w\n</pre>\n<p>\nwhere <code>i</code> is the current of the machine and <code>w</code> is the actual angular velocity.\nThe dependency of the stray load torque on the angular velocity is modeled by the exponent <code>power_w</code>.\n</p>\n<h4>See also</h4>\n<p>\n<a href=\"modelica://Modelica.Electrical.Machines.Losses.StrayLoadParameters\">StrayLoad parameters</a>\n</p>\n<p>\nIf it is desired to neglect stray load losses, set <code>strayLoadParameters.PRef = 0</code> (this is the default).\n</p>\n</html>"));
end StrayLoad;