model VariableResistor "Single phase variable resistor"
import Modelica.ComplexMath.real;
import Modelica.ComplexMath.conj;
extends Interfaces.OnePort;
parameter Modelica.SIunits.Temperature T_ref = 293.15 "Reference temperature";
parameter Modelica.SIunits.LinearTemperatureCoefficient alpha_ref = 0 "Temperature coefficient of resistance (R_actual = R_ref*(1 + alpha_ref*(heatPort.T - T_ref))";
extends Modelica.Electrical.Analog.Interfaces.ConditionalHeatPort(T = T_ref);
Modelica.SIunits.Resistance R_actual "Resistance = R_ref*(1 + alpha_ref*(heatPort.T - T_ref))";
Modelica.Blocks.Interfaces.RealInput R_ref(unit = "Ohm") "Variable resistance"
annotation (Placement(
transformation(
origin = {0, 120},
extent = {
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{20, 20}},
rotation = 270),
iconTransformation(
extent = {
{-20, -20},
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rotation = 270,
origin = {0, 120})));
equation
assert(Modelica.Constants.eps <= 1 + alpha_ref * (T_heatPort - T_ref), "Temperature outside scope of model!");
v = R_actual * i;
LossPower = real(v * conj(i));
R_actual = R_ref * (1 + alpha_ref * (T_heatPort - T_ref));
annotation (
defaultComponentName = "resistor",
Icon(graphics = {
Line(
points = {
{60, 0},
{90, 0}},
color = {85, 170, 255}),
Line(
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textString = "%name",
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Documentation(info = "<html>\n\n<p>\nThe linear resistor connects the voltage <code><u>v</u></code> with the\ncurrent <code><u>i</u></code> by <code><u>i</u>*R = <u>v</u></code>.\nThe resistance <code>R</code> is given as input signal.\n</p>\n\n<p>\nThe variable resistor model also has an optional\n<a href=\"modelica://Modelica.Electrical.Analog.Interfaces.ConditionalHeatPort\">conditional heat port</a>.\nA linear temperature dependency of the resistance is also taken into account.\n</p>\n\n<h4>Note</h4>\n<p>\nA zero crossing of the R signal could cause singularities due to the actual structure of the connected network.\n</p>\n\n<h4>See also</h4>\n<p>\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Resistor\">Resistor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Conductor\">Conductor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Capacitor\">Capacitor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Inductor\">Inductor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Impedance\">Impedance</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.Admittance\">Admittance</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.VariableConductor\">Variable conductor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.VariableCapacitor\">Variable capacitor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.VariableInductor\">Variable inductor</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.VariableImpedance\">Variable impedance</a>,\n<a href=\"modelica://Modelica.Electrical.QuasiStationary.SinglePhase.Basic.VariableAdmittance\">Variable admittance</a>\n</p>\n</html>"));
end VariableResistor;