Modelica - 增量不符合條件

Question

我正在Wolfram System Modeler中創建Max Per Interval塊。

爲了方便我解釋，我只是最大價值指數增量設置爲10

block HighWaterMarkPerInterval 
    extends Modelica.Blocks.Interfaces.SISO; 
protected 
    Integer index; 
    Real currentMax; 
    Real endTimes[1, 45] = [30812532.2, 32037805, 33265581.8, 34493233.8, 35720861.5, 36948483, 38176307.7, 39426940.6, 40654485.4, 41882212.1, 43109672.7, 44337076, 45564265.7, 46793039.6, 48045130.9, 50749960.3, 52040090.6, 53558507.7, 54814537.3, 56331978.2, 57587753.3, 59105952.9, 60362517.8, 61879307.8, 63136031.5, 64363411.4, 65590464.3, 67738027.40000001, 84725789.8, 87831338.09999999, 89030965.40000001, 90258821.8, 91486663.5, 92714210.3, 93941727.7, 95166770.3, 97283519, 99434222.90000001, 100658067.1, 102807019, 104030032.7, 106179193, 107402090, 109550214.2, 110771545.3]; 
algorithm 
    if endTimes[1, index] < time then 
    index := pre(index) + 1; 
    currentMax := 0; 
    else 
    currentMax := 10; // Constant to until I get logic working 
    end if; 
initial algorithm 
    index := 0; 
equation 
    y = currentMax; 
end HighWaterMarkPerInterval; 

當跑，到無窮遠馬上蝙蝠。我認爲我的邏輯有問題，但我無法想象它。

代碼應檢查是否仍處於間隔時間內，當我們跨越下一個間隔時間時，它將「currentMax」值設置爲零。這將重置我在另一個塊中實現的最大值。

任何幫助，將不勝感激。謝謝。

編輯：代碼節表格示例。

model HighWaterMarkPerInterval 
    annotation(Diagram(coordinateSystem(extent = {{-148.5, -105}, {148.5, 105}}, preserveAspectRatio = true, initialScale = 0.1, grid = {5, 5}))); 
    extends Modelica.Blocks.Interfaces.SISO; 
    Modelica.Blocks.Math.Max maxblock(u1 = currentMax, u2 = u); 
    Real flybyEnds[1, 45] = [30813151,32038322,33266015, truncated for space saving...]; 
    Integer index; 
    Real currentMax; 
initial equation 
    index = 1; 
    currentMax = 0; 
algorithm 
    // When we are in the interval continually grab max block output and output currentMax 
    when {time>=flybyEnds[1, index-1], time <=flybyEnds[1,index]} then 
    currentMax := pre(maxblock.y); 
    y := currentMax; 
    end when; 
    // When we move to the next interval reset current max and move to the next interval 
    when time > flybyEnds[1, index] then 
    currentMax := 0; 
    index := pre(index) + 1; 
    end when; 
end HighWaterMarkPerInterval; 

Answer 1

您需要使用when，不if。您可以在Modelica by Example中找到關於它們之間的差異以及它們之間的差異的討論。

此問題在SO上都有討論here和here。

下面是一個例子（沒有經過充分測試，但它顯示的基本想法）：

model HighWaterMarkPerInterval 
    extends Modelica.Blocks.Interfaces.SISO; 
    parameter Modelica.SIunits.Time sample_rate=3600; 
    Real flybyEnds[45] = {30813151,32038322,33266015,...}; 
    Integer index; 
    Real currentMax; 
initial algorithm 
    // Specify the first time we are interested in... 
    index := 1; 
algorithm 
    // At the start of the simulation, the initial max for the current 
    // interval [0,30813151] is whatever u is. The initial output value 
    // is also the initial value for u 
    when initial() then 
    currentMax := u 
    y := u; 
    end when; 

    // Check at some sample rate (faster than the flyby interval!) 
    // if u > currentMax... 
    when sample(sample_rate, sample_rate) then 
    // New currentMax is the larger of either currentMax or u 
    // when the sample took place 
    currentMax := max(pre(currentMax), pre(u)); 
    end when; 

    // At the end of the "flyby", record the maximum found since 
    // the last flyby and specify the next flyby index. 
    when time>=flybyEnd[index] then 
    // New output is the value of currentMax from this interval 
    y := pre(currentMax); 
    // Now reset currentMax 
    currentMax := pre(u); 
    // Increment index up to the length of flybyEnd 
    index := min(pre(index)+1, size(flybyEnd,1)); 
    end when; 
end HighWaterMarkPerInterval;