modelica · AHaumer · May 29, 2025 · May 29, 2025 · May 30, 2025 · Jun 3, 2025
diff --git a/Modelica/Electrical/Machines/BasicMachines/Components/ZeroImpedance.mo b/Modelica/Electrical/Machines/BasicMachines/Components/ZeroImpedance.mo
@@ -0,0 +1,30 @@
+within Modelica.Electrical.Machines.BasicMachines.Components;
+model ZeroImpedance "Zero system impedance"
+  extends Analog.Interfaces.OnePort(i(start=0));
+  parameter SI.Inductance L "Inductance";
+  parameter Boolean useZeroSystem=true "= true, if zero current is explicitely computed" annotation(Evaluate = true);
+equation
+  if useZeroSystem then
+    v = L*der(i);
+  else
+    i = 0;
+  end if;
+
+  annotation (Icon(graphics={
+        Line(points={{-90,0},{-60,0}}, color={0,0,255}),
+        Line(points={{62,0},{90,0}}, color={0,0,255}),
+        Ellipse(extent={{-50,30},{-8,-32}}, lineColor={0,0,255}),
+        Ellipse(extent={{-20,30},{22,-32}}, lineColor={0,0,255}),
+        Ellipse(extent={{10,30},{52,-32}}, lineColor={0,0,255}),
+        Text(
+          extent={{-150,50},{150,90}},
+          textString="%name",
+          textColor={0,0,255}),
+        Rectangle(extent={{-60,30},{-50,-32}}, lineColor={28,108,200}),
+        Rectangle(extent={{52,30},{62,-32}}, lineColor={28,108,200})}),
+      Documentation(info="<html>
+<p>
+For a short explanation of the zero system see <a href=\"modelica://Modelica.Magnetic.FundamentalWave.UsersGuide.ZeroSystem\">the User&apos;s Guide of the FundamentalWave library</a>.
+</p>
+</html>"));
+end ZeroImpedance;
diff --git a/Modelica/Electrical/Machines/BasicMachines/Components/package.order b/Modelica/Electrical/Machines/BasicMachines/Components/package.order
@@ -1,6 +1,7 @@
 PartialAirGap
 AirGapS
 AirGapR
+ZeroImpedance
 Inductor
 SquirrelCage
 DamperCage

diff --git a/Modelica/Electrical/Machines/Examples/InductionMachines/IMC_YD.mo b/Modelica/Electrical/Machines/Examples/InductionMachines/IMC_YD.mo
@@ -16,6 +16,7 @@ model IMC_YD
   Machines.BasicMachines.InductionMachines.IM_SquirrelCage aimc(
     p=aimcData.p,
     fsNominal=aimcData.fsNominal,
+    useZeroSystem=false,
     Rs=aimcData.Rs,
     TsRef=aimcData.TsRef,
     alpha20s(displayUnit="1/K") = aimcData.alpha20s,

diff --git a/Modelica/Electrical/Machines/Interfaces/PartialBasicInductionMachine.mo b/Modelica/Electrical/Machines/Interfaces/PartialBasicInductionMachine.mo
@@ -5,6 +5,8 @@ partial model PartialBasicInductionMachine
   parameter Integer p(min=1, start=2) "Number of pole pairs (Integer)";
   parameter SI.Frequency fsNominal(start=50)
     "Nominal frequency";
+  parameter Boolean useZeroSystem=true "= true, if zero current is explicitely computed"
+    annotation(Evaluate=true);
   parameter SI.Temperature TsOperational(start=293.15)
     "Operational temperature of stator resistance" annotation (Dialog(group=
          "Operational temperatures", enable=not useThermalPort));
@@ -81,7 +83,8 @@ partial model PartialBasicInductionMachine
         extent={{-10,-10},{10,10}},
         rotation=270,
         origin={20,20})));
-  Modelica.Electrical.Analog.Basic.Inductor lszero(final L=Lszero)
+  BasicMachines.Components.ZeroImpedance    lszero(final L=Lszero, final
+      useZeroSystem=useZeroSystem)
     annotation (Placement(transformation(extent={{0,40},{-20,60}})));
   Machines.Losses.InductionMachines.Core statorCore(
     final coreParameters=statorCoreParameters,

diff --git a/Modelica/Electrical/Machines/UsersGuide/Concept.mo b/Modelica/Electrical/Machines/UsersGuide/Concept.mo
@@ -13,7 +13,8 @@ class Concept "Concept"
 <li>constant parameters, i.e., no saturation, no skin effect</li>
 </ul>
 <p>
-You may have a look at a short summary of space phasor theory at <a href=\"https://www.haumer.at/refimg/SpacePhasors.pdf\">https://www.haumer.at/refimg/SpacePhasors.pdf</a>
+You may have a look at a short summary of space phasor theory at <a href=\"https://www.haumer.at/refimg/SpacePhasors.pdf\">https://www.haumer.at/refimg/SpacePhasors.pdf</a><br>
+For a short explanation of the zero system see <a href=\"modelica://Modelica.Magnetic.FundamentalWave.UsersGuide.ZeroSystem\">the User&apos;s Guide of the FundamentalWave library</a>.
 </p>
 <strong>Further development:</strong>
 <ul>

diff --git a/Modelica/Electrical/Polyphase/Basic/ZeroInductor.mo b/Modelica/Electrical/Polyphase/Basic/ZeroInductor.mo
@@ -2,15 +2,21 @@ within Modelica.Electrical.Polyphase.Basic;
 model ZeroInductor "Linear zero sequence inductor"
   extends Polyphase.Interfaces.OnePort;
   parameter SI.Inductance Lzero "Zero sequence inductance";
+  parameter Boolean useZeroSystem=true "= true, if zero current is explicitely computed" annotation(Evaluate = true);
   SI.Current i0;
   SI.Voltage v0;
 equation
   m*i0 = sum(i);
-  v0 = Lzero*der(i0);
+  if useZeroSystem then
+    v0 = Lzero*der(i0);
+  else
+    i0 = 0;
+  end if;
   v = fill(v0, m);
   annotation (defaultComponentName="inductor", Documentation(info="<html>
 <p>
 Model of a polyphase zero sequence inductor.
+For a short explanation of the zero system see <a href=\"modelica://Modelica.Magnetic.FundamentalWave.UsersGuide.ZeroSystem\">the User&apos;s Guide of the FundamentalWave library</a>.
 </p>
 <h4>Implementation</h4>
 <blockquote><pre>
@@ -30,5 +36,7 @@ v = Lzero*sum(der(i)) = Lzero*der(sum(i))
           textColor={0,0,255}),
         Text(
           extent={{-150,-80},{150,-40}},
-          textString="m=%m")}));
+          textString="m=%m"),
+        Rectangle(extent={{-60,30},{-50,-32}}, lineColor={28,108,200}),
+        Rectangle(extent={{52,30},{62,-32}},   lineColor={28,108,200})}));
 end ZeroInductor;
diff --git a/Modelica/Magnetic/FundamentalWave/BaseClasses/Machine.mo b/Modelica/Magnetic/FundamentalWave/BaseClasses/Machine.mo
@@ -15,6 +15,8 @@ partial model Machine "Base model of machines"
   parameter Integer p(min=1, start=2) "Number of pole pairs (Integer)";
   parameter SI.Frequency fsNominal(start=50)
     "Nominal frequency";
+  parameter Boolean useZeroSystem=true "= true, if zero current is explicitely computed"
+    annotation(Evaluate=true);
   parameter SI.Temperature TsOperational(start=293.15)
     "Operational temperature of stator resistance" annotation (Dialog(group=
          "Operational temperatures", enable=not useThermalPort));
@@ -116,6 +118,7 @@ partial model Machine "Base model of machines"
     final TRef=TsRef,
     final Lsigma=Lssigma,
     final ratioCommonLeakage=ratioCommonStatorLeakage,
+    final useZeroSystem=useZeroSystem,
     final effectiveTurns=effectiveStatorTurns,
     final TOperational=TsOperational,
     final GcRef=statorCoreParameters.GcRef,

diff --git a/Modelica/Magnetic/FundamentalWave/BasicMachines/Components/SymmetricPolyphaseWinding.mo b/Modelica/Magnetic/FundamentalWave/BasicMachines/Components/SymmetricPolyphaseWinding.mo
@@ -43,6 +43,7 @@ model SymmetricPolyphaseWinding
   parameter Real ratioCommonLeakage(final min=0, final max=1)=1
     "Ratio of common stray inductance / total stray inductance";
   parameter SI.Inductance Lzero "Zero sequence inductance of winding";
+  parameter Boolean useZeroSystem=true "= true, if zero current is explicitely computed";
   parameter Real effectiveTurns=1 "Effective number of turns per phase";
   parameter SI.Conductance GcRef "Electrical reference core loss reluctance";
   final parameter Integer nBase=Modelica.Electrical.Polyphase.Functions.numberOfSymmetricBaseSystems(m)
@@ -76,7 +77,8 @@ model SymmetricPolyphaseWinding
     final Lsigma=(1 - ratioCommonLeakage)*Lsigma)
                                             "Symmetric winding"
     annotation (Placement(transformation(extent={{-10,-20},{10,0}})));
-  Modelica.Electrical.Polyphase.Basic.ZeroInductor zeroInductor(final m=m, final Lzero=Lzero)
+  Modelica.Electrical.Polyphase.Basic.ZeroInductor zeroInductor(final m=m, final Lzero=Lzero,
+    final useZeroSystem=useZeroSystem)
     if mBase<>2 "Zero sequence inductance of winding"
     annotation (Placement(transformation(
         origin={-70,-30},

diff --git a/Modelica/Magnetic/FundamentalWave/Examples/BasicMachines/InductionMachines/IMC_YD.mo b/Modelica/Magnetic/FundamentalWave/Examples/BasicMachines/InductionMachines/IMC_YD.mo
@@ -17,6 +17,7 @@ model IMC_YD
   Magnetic.FundamentalWave.BasicMachines.InductionMachines.IM_SquirrelCage aimc(
     p=aimcData.p,
     fsNominal=aimcData.fsNominal,
+    useZeroSystem=false,
     TsRef=aimcData.TsRef,
     alpha20s(displayUnit="1/K") = aimcData.alpha20s,
     Jr=aimcData.Jr,
@@ -37,8 +38,7 @@ model IMC_YD
     TsOperational=293.15,
     effectiveStatorTurns=aimcData.effectiveStatorTurns,
     alpha20r=aimcData.alpha20r,
-    TrOperational=293.15,
-    stator(zeroInductor(i0(nominal=10))))
+    TrOperational=293.15)
     annotation (Placement(transformation(extent={{20,10},{40,30}})));
   Modelica.Electrical.Machines.Sensors.CurrentQuasiRMSSensor currentQuasiRMSSensor
     annotation (Placement(transformation(

diff --git a/Modelica/Magnetic/FundamentalWave/UsersGuide/ZeroSystem.mo b/Modelica/Magnetic/FundamentalWave/UsersGuide/ZeroSystem.mo
@@ -0,0 +1,27 @@
+within Modelica.Magnetic.FundamentalWave.UsersGuide;
+class ZeroSystem "Explanation of the zero system"
+  extends Modelica.Icons.Information;
+  annotation (Documentation(info="<html>
+<p>
+The polyphase winding relates the currents to the magnetic potential phasor of the fundamental wave and the derivative of the magnetic flux phasor of the fundamental wave to the voltages, 
+taking the orientation of the phases into account. However, for the number of phases <code>m &gt; 2</code> the zero sequence system has to be treated with care. 
+This happens in the zero inductance:
+</p>
+<p>
+<code>i0 = sum(i)/m;</code><br>
+<code>v0 = Lzero*der(i0);</code><br>
+<code>v0</code> is included in all phases with the same phase shift.
+</p>
+<p>
+This is equivalent to the zero inductor used in the 
+<a href=\"modelica://Modelica.Electrical.Machines.Interfaces.PartialBasicInductionMachine\">machine model of <code>Modelica.Electrical.Machines</code></a> after applying 
+space phasor transformation.
+</p>
+<p>
+In some cases it could be desired to suppress the calculation of the zero system. This can be done in both machine models (<code>Modelica.Magnetic.FundamentalWave</code> and 
+<code>Modelica.Electrical.Machines</code>) by setting the Boolean parameter <code>useZeroSystem = false</code> (which by default is <code>true</code>). 
+This ensures that the zero current is equal to zero and there is no need to calculate it:<br>
+<code>i0 = 0;</code>
+</p>
+</html>"));
+end ZeroSystem;
diff --git a/Modelica/Magnetic/FundamentalWave/UsersGuide/package.order b/Modelica/Magnetic/FundamentalWave/UsersGuide/package.order
@@ -1,6 +1,7 @@
 Concept
 Polyphase
 WindingModel
+ZeroSystem
 Parameters
 Contact
 ReleaseNotes

diff --git a/...a/Magnetic/QuasiStatic/FundamentalWave/Examples/BasicMachines/InductionMachines/IMC_YD.mo b/...a/Magnetic/QuasiStatic/FundamentalWave/Examples/BasicMachines/InductionMachines/IMC_YD.mo
@@ -78,6 +78,7 @@ model IMC_YD "Induction machine with squirrel cage starting Y-D"
   Magnetic.FundamentalWave.BasicMachines.InductionMachines.IM_SquirrelCage imc(
     p=imcData.p,
     fsNominal=imcData.fsNominal,
+    useZeroSystem=false,
     TsRef=imcData.TsRef,
     alpha20s(displayUnit="1/K") = imcData.alpha20s,
     Jr=imcData.Jr,
@@ -98,8 +99,7 @@ model IMC_YD "Induction machine with squirrel cage starting Y-D"
     TsOperational=293.15,
     effectiveStatorTurns=imcData.effectiveStatorTurns,
     alpha20r=imcData.alpha20r,
-    TrOperational=293.15,
-    stator(zeroInductor(i0(nominal=10))))
+    TrOperational=293.15)
     annotation (Placement(transformation(extent={{20,-90},{40,-70}})));
   Modelica.Electrical.Machines.Sensors.CurrentQuasiRMSSensor
                                                     currentQuasiRMSSensor annotation (Placement(transformation(extent={{-10,10},{10,-10}}, rotation=270,