model Potentiometer "Adjustable resistor"
parameter SI.Resistance R(start = 1) "Resistance at temperature T_ref";
parameter SI.Temperature T_ref = 293.15 "Reference temperature";
parameter SI.LinearTemperatureCoefficient alpha = 0 "Temperature coefficient of resistance (R_actual = R*(1 + alpha*(T_heatPort - T_ref))";
extends Modelica.Electrical.Analog.Interfaces.ConditionalHeatPort(T = T_ref);
parameter Boolean useRinput = false "use input for 0<r<1 (else constant)"
annotation (
Evaluate = true,
HideResult = true,
Dialog(group = "potentiometer"));
parameter Real rConstant(final min = 0, final max = 1) = 0.5 "Contact between n (r=0) and p (r=1)"
annotation (Dialog(
group = "potentiometer",
enable = not useRinput));
SI.Resistance Rp "Actual resistance between pin_p and contact";
SI.Resistance Rn "Actual resistance between contact and pin_n";
Modelica.Electrical.Analog.Interfaces.PositivePin pin_p annotation (Placement(transformation(extent = {
{-110, -10},
{-90, 10}})));
Modelica.Electrical.Analog.Interfaces.PositivePin contact annotation (Placement(
transformation(extent = {
{90, -110},
{110, -90}}),
iconTransformation(extent = {
{90, -110},
{110, -90}})));
Modelica.Electrical.Analog.Interfaces.NegativePin pin_n annotation (Placement(transformation(extent = {
{90, -10},
{110, 10}})));
Modelica.Blocks.Interfaces.RealInput r if useRinput annotation (Placement(
transformation(
extent = {
{-20, -20},
{20, 20}},
rotation = 90,
origin = {-100, -120}),
iconTransformation(
extent = {
{-20, -20},
{20, 20}},
rotation = 90,
origin = {-100, -120})));
protected
Modelica.Blocks.Sources.Constant rConst(final k = rConstant) if not useRinput annotation (Placement(transformation(
extent = {
{-10, -10},
{10, 10}},
rotation = 270,
origin = {-90, -50})));
Modelica.Blocks.Interfaces.RealInput rInt annotation (Placement(transformation(extent = {
{-84, -84},
{-76, -76}})));
equation
connect(rInt,r) annotation (Line(
points = {
{-80, -80},
{-100, -80},
{-100, -120}},
color = {0, 0, 127}));
connect(rInt,rConst.y) annotation (Line(
points = {
{-80, -80},
{-90, -80},
{-90, -61}},
color = {0, 0, 127}));
pin_p.i + pin_n.i + contact.i = 0;
LossPower = (pin_p.v - contact.v) * pin_p.i + (pin_n.v - contact.v) * pin_n.i;
Rn = R * (1 + alpha * (T_heatPort - T_ref)) * min(1, max(0, rInt));
Rp = R * (1 + alpha * (T_heatPort - T_ref)) * (1 - min(1, max(0, rInt)));
pin_n.v - contact.v = Rn * pin_n.i;
pin_p.v - contact.v = Rp * pin_p.i;
annotation (
Icon(
coordinateSystem(
preserveAspectRatio = false,
extent = {
{-100, -100},
{100, 100}}),
graphics = {
Rectangle(
extent = {
{-70, 30},
{70, -30}},
lineColor = {0, 0, 255},
fillColor = {255, 255, 255},
fillPattern = FillPattern.Solid),
Line(
points = {
{-90, 0},
{-70, 0}},
color = {0, 0, 255}),
Line(
points = {
{70, 0},
{90, 0}},
color = {0, 0, 255}),
Line(
visible = useHeatPort,
points = {
{0, -100},
{0, -30}},
color = {127, 0, 0},
pattern = LinePattern.Dot),
Line(
points = {
{0, 40},
{0, -40},
{100, -80},
{100, -90}},
color = {0, 0, 255}),
Line(
visible = useRinput,
points = {
{-100, -90},
{-100, -80},
{0, -40}},
color = {0, 0, 255},
pattern = LinePattern.Dot),
Line(
visible = useHeatPort,
points = {
{0, -90},
{0, -40}},
color = {127, 0, 0},
pattern = LinePattern.Dot),
Polygon(
points = {
{0, -30},
{-4, -40},
{4, -40},
{0, -30}},
lineColor = {0, 0, 255},
fillColor = {0, 0, 255},
fillPattern = FillPattern.Solid),
Text(
extent = {
{-150, 90},
{150, 50}},
textString = "%name",
lineColor = {0, 0, 255})}),
Documentation(info = "<html>\n <p>This models a potentiometer where the sliding contact is placed between pin_n (r = 0) and pin_p (r = 1), dependent on either the parameter rConstant or the signal input r.</p>\n <p>The total resistance R is temperature dependent.</p>\n </html>"));
end Potentiometer;