如何在 Modelica 中更新变量和模拟时间？

Question

'我不熟悉Modelica语言。这是我的问题：我有两个 Real 类型变量 K 和 A，它们用于计算模型的输出，并且在每个时间步我都想更新 K 和 A 以重新计算输出。我该怎么做？'

Answer 1

不清楚你问什么，但由于你似乎是 Modelica 的新手，我会从最明显的解决方案开始：只给出 K 和 A 的方程式，例如：

model M
  output Real K;
  output Real A;
  Real x;
equation
  K=2*x;
  A=Modelica.Math.sin(time);
  der(x)=1-x;
end M;

在每个时间步都有基于这些方程的 K 和 A 的新值。（如果 K 和 A 是采样或时钟变量，它会变得更复杂。）

Answer 2

以下模型展示了我在评论中写的内容。模拟 inputOutput.FullModel 会产生您可能正在寻找的控制选项。

使用 OpenModelica 测试了 10 秒的模拟时间。

编辑：我影响了 X 的导数而不是变量本身，因为大多数情况下，如果两个变量 a 和 b 间断地相互影响。

package inputOutput
  model M1
    Modelica.Blocks.Interfaces.RealInput X annotation(
      Placement(visible = true, transformation(origin = {-120, 0}, extent = {{-20, -20}, {20, 20}}, rotation = 0), iconTransformation(origin = {-120, 0}, extent = {{-20, -20}, {20, 20}}, rotation = 0)));
  Modelica.Blocks.Interfaces.RealOutput K annotation(
      Placement(visible = true, transformation(origin = {110, 48}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {110, 48}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Blocks.Interfaces.RealOutput A annotation(
      Placement(visible = true, transformation(origin = {110, -50}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {110, -50}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  equation
    K = if X > 1 then 1.5 else 0.8;
    A = if X > 0 then 0.5 else -0.5;
  end M1;

  model M2
  Modelica.Blocks.Interfaces.RealInput K annotation(
      Placement(visible = true, transformation(origin = {-120, 50}, extent = {{-20, -20}, {20, 20}}, rotation = 0), iconTransformation(origin = {-120, 50}, extent = {{-20, -20}, {20, 20}}, rotation = 0)));
  Modelica.Blocks.Interfaces.RealOutput X(start=0) annotation(
      Placement(visible = true, transformation(origin = {110, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0), iconTransformation(origin = {110, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Blocks.Interfaces.RealInput A annotation(
      Placement(visible = true, transformation(origin = {-120, -50}, extent = {{-20, -20}, {20, 20}}, rotation = 0), iconTransformation(origin = {-120, -50}, extent = {{-20, -20}, {20, 20}}, rotation = 0)));
  equation
    der(X) = A + sin(time)*K;
  end M2;

  model FullModel
    M1 m1 annotation(
      Placement(visible = true, transformation(origin = {-48, 4}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
    M2 m2 annotation(
      Placement(visible = true, transformation(origin = {34, 4}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  equation
    connect(m1.A, m2.A) annotation(
      Line(points = {{-38, 0}, {22, 0}, {22, -2}, {24, -2}}, color = {0, 0, 127}));
    connect(m2.K, m1.K) annotation(
      Line(points = {{22, 10}, {-38, 10}, {-38, 8}, {-36, 8}}, color = {0, 0, 127}));
  connect(m2.X, m1.X) annotation(
      Line(points = {{46, 4}, {66, 4}, {66, 52}, {-74, 52}, {-74, 4}, {-60, 4}, {-60, 4}}, color = {0, 0, 127}));
  end FullModel;
  annotation(
    uses(Modelica(version = "3.2.2")));

end inputOutput;

Answer 3

您的 link https://openmodelica.org/forum/default-topic/2339-modelica-variable-behavior 中的模型可以重写为类似的东西（除了我没有用 OpenModelica 测试过）。这表示您 应该始终包含代码 - 因为您的描述根本不清楚。

model TimeVarTest
  Modelica.SIunits.Time timeVar(start = 0);
  Modelica.SIunits.Time timeOut(start = 0);
  Modelica.Blocks.Tables.CombiTable1Ds tableVar(table = [0,0;1,0.5]);
  Integer state(start = 0);
algorithm 
  if state == 0 then
    // Action 
    tableVar.u := time-timeVar;
    // Transition 
  end if;
    when pre(state)==0 and time - timeVar > 1 then
      state := 1;
      timeVar := time;
    end when;

  if state == 1 then
  // Action 
  tableVar.u := 1;
  // Transition 
  end if;
  when pre(state)==1 and time - timeVar > 2 then
    state := 0;
    timeVar := time;
  end when;
equation 
  timeOut = tableVar.y[1];
annotation (
    experiment(StartTime = 0, StopTime = 10, Tolerance = 1e-06, Interval = 0.1));
end TimeVarTest;

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