model LeakageWithCoefficient "Leakage reluctance with respect to the reluctance of a useful flux path (not for dynamic simulation of actuators)"
extends FluxTubes.Interfaces.PartialLeakage;
parameter SI.CouplingCoefficient c_usefulFlux = 0.7 "Ratio useful flux/(leakage flux + useful flux) = useful flux/total flux";
input SI.Reluctance R_mUsefulTot "Total reluctance of useful flux path as reference"
annotation (Dialog(
group = "Reference reluctance",
groupImage = "modelica://Modelica/Resources/Images/Magnetic/FluxTubes/Basic/LeakageWithCoefficient.png"));
equation
(1 - c_usefulFlux) * R_m = c_usefulFlux * R_mUsefulTot;
annotation (
defaultComponentName = "leakage",
Documentation(info = "<html>\n<p>\nDifferently from the flux tube elements of package <a href=\"modelica://Modelica.Magnetic.FluxTubes.Shapes.Leakage\">Shapes.Leakage</a>\nthat are calculated from their geometry, this leakage reluctance is calculated with reference to the total reluctance of a useful flux path. Please refer to the <strong>Parameters</strong> section for an illustration of the resulting magnetic network. Exploiting <em>Kirchhoff</em>'s generalized current law, the leakage reluctance is calculated by means of a coupling coefficient c_usefulFlux.\n</p>\n\n<h4>Attention:</h4>\n\n<p>\nThis element must <strong>not</strong> be used <strong>for dynamic simulation of</strong> electro-magneto-mechanical <strong>actuators</strong>, where the shape of at least one flux tube element with reluctance force generation in the useful flux path changes with armature motion (e.g., air gap). This change results in a non-zero derivative dG_m/dx of those elements permeance G_m with respect to armature position x, which in turn will lead to a non-zero derivative of the leakage permeance with respect to armature position. This would generate a reluctance force in the leakage element that is not accounted for properly. <a href=\"modelica://Modelica.Magnetic.FluxTubes.Shapes.Force.LeakageAroundPoles\">Shapes.Force.LeakageAroundPoles</a> provides a simple leakage reluctance with force generation.\n</p>\n</html>"));
end LeakageWithCoefficient;