Eddy current sources (modelica#3976)

beutlich · Jun 10, 2022 · 569c525 · 569c525
1 parent 8690ef6
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Showing 4 changed files with 53 additions and 16 deletions.
diff --git a/Modelica/Mechanics/Rotational/Examples/EddyCurrentBrake.mo b/Modelica/Mechanics/Rotational/Examples/EddyCurrentBrake.mo
@@ -2,6 +2,7 @@ within Modelica.Mechanics.Rotational.Examples;
 model EddyCurrentBrake "Demonstrate the usage of the rotational eddy current brake"
   extends Modelica.Icons.Example;
   Modelica.Mechanics.Rotational.Sources.EddyCurrentTorque eddyCurrentTorque(
+    useExcitationInput=true,
     tau_nominal=100,
     w_nominal=10,
     useSupport=false,
@@ -19,11 +20,19 @@ model EddyCurrentBrake "Demonstrate the usage of the rotational eddy current bra
         extent={{-10,-10},{10,10}},
         rotation=180,
         origin={-10,-30})));
+  Blocks.Sources.Ramp ramp(
+    height=1,
+    duration=0.1,
+    offset=0,
+    startTime=0.1)
+    annotation (Placement(transformation(extent={{-50,-10},{-30,10}})));
 equation
   connect(eddyCurrentTorque.flange, inertia.flange_a)
     annotation (Line(points={{10,0},{16,0},{20,0}}));
   connect(eddyCurrentTorque.heatPort, heatCapacitor.port) annotation (Line(
         points={{-10,-10},{-10,-15},{-10,-20}}, color={191,0,0}));
+  connect(ramp.y, eddyCurrentTorque.excitation)
+    annotation (Line(points={{-29,0},{-12,0}}, color={0,0,127}));
   annotation (
     experiment(StopTime=1.0, Interval=0.001),
     Documentation(info="<html>

diff --git a/Modelica/Mechanics/Rotational/Sources/EddyCurrentTorque.mo b/Modelica/Mechanics/Rotational/Sources/EddyCurrentTorque.mo
@@ -1,8 +1,10 @@
 within Modelica.Mechanics.Rotational.Sources;
 model EddyCurrentTorque "Simple model of a rotational eddy current brake"
   import Modelica.Electrical.Machines.Thermal.linearTemperatureDependency;
-  parameter SI.Torque tau_nominal
-    "Maximum torque (always braking)";
+  parameter Boolean useExcitationInput=false "Enable signal input for excitation";
+  parameter Real constantExcitation=1 "Excitation=1 to reach maximum torque"
+    annotation(Dialog(enable=not useExcitationInput));
+  parameter SI.Torque tau_nominal "Maximum torque (always braking)";
   parameter SI.AngularVelocity w_nominal(min=Modelica.Constants.eps)
     "Nominal speed (leads to maximum torque) at reference temperature";
   parameter SI.Temperature TRef(start=293.15)
@@ -11,18 +13,23 @@ model EddyCurrentTorque "Simple model of a rotational eddy current brake"
     Modelica.Electrical.Machines.Thermal.LinearTemperatureCoefficient20
     alpha20(start=0) "Temperature coefficient of material";
   extends Modelica.Mechanics.Rotational.Interfaces.PartialTorque;
-  extends
-    Modelica.Thermal.HeatTransfer.Interfaces.PartialElementaryConditionalHeatPort;
-  SI.Torque tau
-    "Accelerating torque acting at flange (= flange.tau)";
-  SI.AngularVelocity w
-    "Angular velocity of flange with respect to support (= der(phi))";
+  extends Modelica.Thermal.HeatTransfer.Interfaces.PartialElementaryConditionalHeatPort;
+  SI.Torque tau "Accelerating torque acting at flange (= flange.tau)";
+  SI.AngularVelocity w "Angular velocity of flange with respect to support (= der(phi))";
   Real w_normalized "Relative speed w/w_nominal";
+  Blocks.Interfaces.RealInput excitation = excitationInternal if useExcitationInput
+    "Excitation"
+    annotation (Placement(transformation(extent={{-140,-20},{-100,20}})));
+protected
+  Real excitationInternal "Excitation";
 equation
+  if not useExcitationInput then
+    excitationInternal = constantExcitation;
+  end if;
   tau = flange.tau;
   w = der(phi);
   w_normalized = w/(w_nominal*linearTemperatureDependency(1, TRef, alpha20, TheatPort));
-  tau = 2*tau_nominal*w_normalized/(1 + w_normalized*w_normalized);
+  tau = 2*tau_nominal*excitationInternal^2*w_normalized/(1 + w_normalized*w_normalized);
   lossPower = tau*w;
   annotation (
     Icon(coordinateSystem(preserveAspectRatio=true, extent={{-100,
@@ -33,6 +40,8 @@ equation
         Line(points={{0,0},{-4,-25},{-8,-41},{-12,-48},{-16,-50},{-20,-49},{-24,-46},{-28,-42},{-32,-38},{-36,-34},{-46,-25},{-56,-18},{-66,-12},{-76,-8}}, color={0,0,127}, smooth=Smooth.Bezier)}),
     Documentation(info="<html>
 <p>This is a simple model of a rotational <strong>eddy current brake</strong>. The torque versus speed characteristic is defined by Kloss' equation.</p>
+<p>The influence of excitation is either constant (<code>useExcitationInput=false</code>) or given by the optional input <code>excitation</code> (<code>useExcitationInput=true</code>). 
+Note that maximum torque depends on square of excitation (magnetic field).</p>
 <p><strong>Thermal behaviour:</strong><br>
 The resistance of the braking disc is influenced by the actual temperature Theatport, which in turn shifts the speed w_nominal at which the (unchanged) maximum torque occurs.<br>
 If the heatPort is not used (useHeatPort = false), the operational temperature remains at the given temperature T.<br>

diff --git a/Modelica/Mechanics/Translational/Examples/EddyCurrentBrake.mo b/Modelica/Mechanics/Translational/Examples/EddyCurrentBrake.mo
@@ -3,6 +3,7 @@ model EddyCurrentBrake "Demonstrate the usage of the translational eddy current
   extends Modelica.Icons.Example;
   Modelica.Mechanics.Translational.Sources.EddyCurrentForce
     eddyCurrentForce(
+    useExcitationInput=true,
     f_nominal=100,
     v_nominal=10,
     useHeatPort=true,
@@ -19,11 +20,19 @@ model EddyCurrentBrake "Demonstrate the usage of the translational eddy current
         extent={{-10,-10},{10,10}},
         rotation=180,
         origin={-10,-30})));
+  Blocks.Sources.Ramp ramp(
+    height=1,
+    duration=0.1,
+    offset=0,
+    startTime=0.1)
+    annotation (Placement(transformation(extent={{-50,-10},{-30,10}})));
 equation
   connect(eddyCurrentForce.flange, mass.flange_a)
     annotation (Line(points={{10,0},{20,0}}, color={0,127,0}));
   connect(eddyCurrentForce.heatPort, heatCapacitor.port) annotation (Line(
         points={{-10,-10},{-10,-15},{-10,-20}}, color={191,0,0}));
+  connect(ramp.y, eddyCurrentForce.excitation)
+    annotation (Line(points={{-29,0},{-12,0}}, color={0,0,127}));
   annotation (
     experiment(StopTime=1.0, Interval=0.001),
     Documentation(info="<html>

diff --git a/Modelica/Mechanics/Translational/Sources/EddyCurrentForce.mo b/Modelica/Mechanics/Translational/Sources/EddyCurrentForce.mo
@@ -1,24 +1,32 @@
 within Modelica.Mechanics.Translational.Sources;
 model EddyCurrentForce "Simple model of a translational eddy current brake"
   import Modelica.Electrical.Machines.Thermal.linearTemperatureDependency;
-  parameter SI.Force f_nominal
-    "Maximum force (always braking)";
+  parameter Boolean useExcitationInput=false "Enable signal input for excitation";
+  parameter Real constantExcitation=1 "Excitation=1 to reach maximum force"
+    annotation(Dialog(enable=not useExcitationInput));
+  parameter SI.Force f_nominal "Constant maximum force (always braking)";
   parameter SI.Velocity v_nominal(min=Modelica.Constants.eps)
     "Nominal speed (leads to maximum force) at reference temperature";
   parameter SI.Temperature TRef(start=293.15)
     "Reference temperature";
-  parameter
-    Modelica.Electrical.Machines.Thermal.LinearTemperatureCoefficient20
+  parameter Modelica.Electrical.Machines.Thermal.LinearTemperatureCoefficient20
     alpha20(start=0) "Temperature coefficient of material";
   extends Modelica.Mechanics.Translational.Interfaces.PartialForce;
   extends Modelica.Thermal.HeatTransfer.Interfaces.PartialElementaryConditionalHeatPort;
-  SI.Velocity v
-    "Velocity of flange with respect to support (= der(s))";
+  SI.Velocity v "Velocity of flange with respect to support (= der(s))";
   Real v_normalized "Relative speed v/v_nominal";
+  Blocks.Interfaces.RealInput excitation = excitationInternal if useExcitationInput
+    "Excitation"
+    annotation (Placement(transformation(extent={{-140,-20},{-100,20}})));
+protected
+  Real excitationInternal "Excitation";
 equation
+  if not useExcitationInput then
+    excitationInternal = constantExcitation;
+  end if;
   v = der(s);
   v_normalized = v/(v_nominal*linearTemperatureDependency(1, TRef, alpha20, TheatPort));
-  f = 2*f_nominal*v_normalized/(1 + v_normalized*v_normalized);
+  f = 2*f_nominal*excitationInternal^2*v_normalized/(1 + v_normalized*v_normalized);
   lossPower = f*v;
   annotation (
     Icon(coordinateSystem(preserveAspectRatio=true, extent={{-100,
@@ -29,6 +37,8 @@ equation
         Line(points={{0,0},{-4,-25},{-8,-41},{-12,-48},{-16,-50},{-20,-49},{-24,-46},{-28,-42},{-32,-38},{-36,-34},{-46,-25},{-56,-18},{-66,-12},{-76,-8}}, color={0,0,127}, smooth=Smooth.Bezier)}),
     Documentation(info="<html>
 <p>This is a simple model of a translational <strong>eddy current brake</strong>. The force versus speed characteristic is defined by Kloss' equation.</p>
+<p>The influence of excitation is either constant (<code>useExcitationInput=false</code>) or given by the optional input <code>excitation</code> (<code>useExcitationInput=true</code>). 
+Note that maximum force depends on square of excitation (magnetic field).</p>
 <p><strong>Thermal behaviour:</strong><br>
 The resistance of the braking fin is influenced by the actual temperature Theatport, which in turn shifts the speed v_nominal at which the (unchanged) maximum torque occurs.<br>
 If the heatPort is not used (useHeatPort = false), the operational temperature remains at the given temperature T.<br>