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Continuous.mo
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Continuous.mo
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within Modelica.Blocks;
package Continuous "Library of continuous control blocks with internal states"
import Modelica.Blocks.Interfaces;
extends Modelica.Icons.Package;
block Integrator "Output the integral of the input signal with optional reset"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Integrator gain";
parameter Boolean use_reset = false "= true, if reset port enabled"
annotation(Evaluate=true, HideResult=true, choices(checkBox=true));
parameter Boolean use_set = false "= true, if set port enabled and used as reinitialization value when reset"
annotation(Dialog(enable=use_reset), Evaluate=true, HideResult=true, choices(checkBox=true));
/* InitialState is the default, because it was the default in Modelica 2.2
and therefore this setting is backward compatible
*/
parameter Init initType=Init.InitialState
"Type of initialization (1: no init, 2: steady state, 3,4: initial output)" annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real y_start=0 "Initial or guess value of output (= state)"
annotation (Dialog(group="Initialization"));
extends Interfaces.SISO(y(start=y_start));
Modelica.Blocks.Interfaces.BooleanInput reset if use_reset "Optional connector of reset signal" annotation(Placement(
transformation(
extent={{-20,-20},{20,20}},
rotation=90,
origin={60,-120})));
Modelica.Blocks.Interfaces.RealInput set if use_reset and use_set "Optional connector of set signal" annotation(Placement(
transformation(
extent={{-20,-20},{20,20}},
rotation=270,
origin={60,120})));
protected
Modelica.Blocks.Interfaces.BooleanOutput local_reset annotation(HideResult=true);
Modelica.Blocks.Interfaces.RealOutput local_set annotation(HideResult=true);
initial equation
if initType == Init.SteadyState then
der(y) = 0;
elseif initType == Init.InitialState or
initType == Init.InitialOutput then
y = y_start;
end if;
equation
if use_reset then
connect(reset, local_reset);
if use_set then
connect(set, local_set);
else
local_set = y_start;
end if;
when local_reset then
reinit(y, local_set);
end when;
else
local_reset = false;
local_set = 0;
end if;
der(y) = k*u;
annotation (
Documentation(info="<html>
<p>
This blocks computes output <strong>y</strong> as
<em>integral</em> of the input <strong>u</strong> multiplied with
the gain <em>k</em>:
</p>
<blockquote><pre>
k
y = - u
s
</pre></blockquote>
<p>
It might be difficult to initialize the integrator in steady state.
This is discussed in the description of package
<a href=\"modelica://Modelica.Blocks.Continuous#info\">Continuous</a>.
</p>
<p>
If the <em>reset</em> port is enabled, then the output <strong>y</strong> is reset to <em>set</em>
or to <em>y_start</em> (if the <em>set</em> port is not enabled), whenever the <em>reset</em>
port has a rising edge.
</p>
</html>"), Icon(coordinateSystem(
preserveAspectRatio=true,
extent={{-100.0,-100.0},{100.0,100.0}}),
graphics={
Line(
points={{-80.0,78.0},{-80.0,-90.0}},
color={192,192,192}),
Polygon(
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{-80.0,90.0},{-88.0,68.0},{-72.0,68.0},{-80.0,90.0}}),
Line(
points={{-90.0,-80.0},{82.0,-80.0}},
color={192,192,192}),
Polygon(
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{90.0,-80.0},{68.0,-72.0},{68.0,-88.0},{90.0,-80.0}}),
Text(
textColor={192,192,192},
extent={{0.0,-70.0},{60.0,-10.0}},
textString="I"),
Text(
extent={{-150.0,-150.0},{150.0,-110.0}},
textString="k=%k"),
Line(
points=DynamicSelect({{-80.0,-80.0},{80.0,80.0}}, if use_reset then {{-80.0,-80.0},{60.0,60.0},{60.0,-80.0},{80.0,-60.0}} else {{-80.0,-80.0},{80.0,80.0}}),
color={0,0,127}),
Line(
visible=use_reset,
points={{60,-100},{60,-80}},
color={255,0,255},
pattern=LinePattern.Dot),
Text(
visible=use_reset,
extent={{-28,-62},{94,-86}},
textString="reset")}));
end Integrator;
block LimIntegrator "Integrator with limited value of the output and optional reset"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Integrator gain";
parameter Real outMax(start=1) "Upper limit of output";
parameter Real outMin=-outMax "Lower limit of output";
parameter Boolean use_reset = false "= true, if reset port enabled"
annotation(Evaluate=true, HideResult=true, choices(checkBox=true));
parameter Boolean use_set = false "= true, if set port enabled and used as reinitialization value when reset"
annotation(Dialog(enable=use_reset), Evaluate=true, HideResult=true, choices(checkBox=true));
parameter Init initType=Init.InitialState
"Type of initialization (1: no init, 2: steady state, 3/4: initial output)"
annotation(Evaluate=true, Dialog(group="Initialization"));
parameter Boolean limitsAtInit = true
"= false, if limits are ignored during initialization (i.e., der(y)=k*u)"
annotation(Evaluate=true, Dialog(group="Initialization"));
parameter Real y_start=0
"Initial or guess value of output (must be in the limits outMin .. outMax)"
annotation (Dialog(group="Initialization"));
parameter Boolean strict=false "= true, if strict limits with noEvent(..)"
annotation (Evaluate=true, choices(checkBox=true), Dialog(tab="Advanced"));
extends Interfaces.SISO(y(start=y_start));
Modelica.Blocks.Interfaces.BooleanInput reset if use_reset "Optional connector of reset signal" annotation(Placement(
transformation(
extent={{-20,-20},{20,20}},
rotation=90,
origin={60,-120})));
Modelica.Blocks.Interfaces.RealInput set if use_reset and use_set "Optional connector of set signal" annotation(Placement(
transformation(
extent={{-20,-20},{20,20}},
rotation=270,
origin={60,120})));
protected
Modelica.Blocks.Interfaces.BooleanOutput local_reset annotation(HideResult=true);
Modelica.Blocks.Interfaces.RealOutput local_set annotation(HideResult=true);
initial equation
if initType == Init.SteadyState then
der(y) = 0;
elseif initType == Init.InitialState or
initType == Init.InitialOutput then
y = y_start;
end if;
equation
if use_reset then
connect(reset, local_reset);
if use_set then
connect(set, local_set);
else
local_set = y_start;
end if;
when local_reset then
reinit(y, if local_set < outMin then outMin elseif local_set > outMax then outMax else local_set);
end when;
else
local_reset = false;
local_set = 0;
end if;
if initial() and not limitsAtInit then
der(y) = k*u;
assert(y >= outMin - 0.001*abs(outMax-outMin) and y <= outMax + 0.001*abs(outMax-outMin),
"LimIntegrator: During initialization the limits have been ignored.\n"
+ "However, the result is that the output y is not within the required limits:\n"
+ " y = " + String(y) + ", outMin = " + String(outMin) + ", outMax = " + String(outMax));
elseif strict then
der(y) = noEvent(if y < outMin and k*u < 0 or y > outMax and k*u > 0 then 0 else k*u);
else
der(y) = if y < outMin and k*u < 0 or y > outMax and k*u > 0 then 0 else k*u;
end if;
annotation (
Documentation(info="<html>
<p>
This blocks computes <strong>y</strong> as <em>integral</em>
of the input <strong>u</strong> multiplied with the gain <em>k</em>. If the
integral reaches a given upper or lower <em>limit</em> and the
input will drive the integral outside of this bound, the
integration is halted and only restarted if the input drives
the integral away from the bounds.
</p>
<p>
It might be difficult to initialize the integrator in steady state.
This is discussed in the description of package
<a href=\"modelica://Modelica.Blocks.Continuous#info\">Continuous</a>.
</p>
<p>
If parameter <strong>limitsAtInit</strong> = <strong>false</strong>, the limits of the
integrator are removed from the initialization problem which
leads to a much simpler equation system. After initialization has been
performed, it is checked via an assert whether the output is in the
defined limits. For backward compatibility reasons
<strong>limitsAtInit</strong> = <strong>true</strong>. In most cases it is best
to use <strong>limitsAtInit</strong> = <strong>false</strong>.
</p>
<p>
If the <em>reset</em> port is enabled, then the output <strong>y</strong> is reset to <em>set</em>
or to <em>y_start</em> (if the <em>set</em> port is not enabled), whenever the <em>reset</em>
port has a rising edge.
</p>
</html>"), Icon(coordinateSystem(
preserveAspectRatio=true,
extent={{-100,-100},{100,100}}), graphics={
Line(points={{-80,78},{-80,-90}}, color={192,192,192}),
Polygon(
points={{-80,90},{-88,68},{-72,68},{-80,90}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points={{-90,-80},{82,-80}}, color={192,192,192}),
Polygon(
points={{90,-80},{68,-72},{68,-88},{90,-80}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(
points=DynamicSelect({{-80,-80},{20,20},{80,20}}, if use_reset then {{-80,-80},{20,20},{60,20},{60,-80},{80,-60}} else {{-80,-80},{20,20},{80,20}}),
color={0,0,127}),
Text(
extent={{0,-10},{60,-70}},
textColor={192,192,192},
textString="I"),
Text(
extent={{-150,-150},{150,-110}},
textString="k=%k"),
Line(
visible=strict,
points=DynamicSelect({{20,20},{80,20}}, if use_reset then {{20,20},{60,20}} else {{20,20},{80,20}}),
color={255,0,0}),
Line(
visible=use_reset,
points={{60,-100},{60,-80}},
color={255,0,255},
pattern=LinePattern.Dot),
Text(
visible=use_reset,
extent={{-28,-62},{94,-86}},
textString="reset")}));
end LimIntegrator;
block Derivative "Approximated derivative block"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Gains";
parameter SI.Time T(min=Modelica.Constants.small) = 0.01
"Time constants (T>0 required; T=0 is ideal derivative block)";
parameter Init initType=Init.NoInit
"Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"
annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real x_start=0 "Initial or guess value of state"
annotation (Dialog(group="Initialization"));
parameter Real y_start=0 "Initial value of output (= state)"
annotation(Dialog(enable=initType == Init.InitialOutput, group=
"Initialization"));
extends Interfaces.SISO;
output Real x(start=x_start) "State of block";
protected
parameter Boolean zeroGain = abs(k) < Modelica.Constants.eps;
initial equation
if initType == Init.SteadyState then
der(x) = 0;
elseif initType == Init.InitialState then
x = x_start;
elseif initType == Init.InitialOutput then
if zeroGain then
x = u;
else
y = y_start;
end if;
end if;
equation
der(x) = if zeroGain then 0 else (u - x)/T;
y = if zeroGain then 0 else (k/T)*(u - x);
annotation (
Documentation(info="<html>
<p>
This blocks defines the transfer function between the
input u and the output y
as <em>approximated derivative</em>:
</p>
<blockquote><pre>
k * s
y = ------------ * u
T * s + 1
</pre></blockquote>
<p>
If you would like to be able to change easily between different
transfer functions (FirstOrder, SecondOrder, ... ) by changing
parameters, use the general block <strong>TransferFunction</strong> instead
and model a derivative block with parameters<br>
b = {k,0}, a = {T, 1}.
</p>
<p>
If k=0, the block reduces to y=0.
</p>
</html>"), Icon(
coordinateSystem(preserveAspectRatio=true,
extent={{-100.0,-100.0},{100.0,100.0}}),
graphics={
Line(points={{-80.0,78.0},{-80.0,-90.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{-80.0,90.0},{-88.0,68.0},{-72.0,68.0},{-80.0,90.0}}),
Line(points={{-90.0,-80.0},{82.0,-80.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{90.0,-80.0},{68.0,-72.0},{68.0,-88.0},{90.0,-80.0}}),
Line(origin = {-24.667,-27.333},
points = {{-55.333,87.333},{-19.333,-40.667},{86.667,-52.667}},
color = {0,0,127},
smooth = Smooth.Bezier),
Text(textColor={192,192,192},
extent={{-30.0,14.0},{86.0,60.0}},
textString="DT1"),
Text(extent={{-150.0,-150.0},{150.0,-110.0}},
textString="k=%k")}));
end Derivative;
block FirstOrder "First order transfer function block (= 1 pole)"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Gain";
parameter SI.Time T(start=1) "Time Constant";
parameter Init initType=Init.NoInit
"Type of initialization (1: no init, 2: steady state, 3/4: initial output)" annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real y_start=0 "Initial or guess value of output (= state)"
annotation (Dialog(group="Initialization"));
extends Interfaces.SISO(y(start=y_start));
initial equation
if initType == Init.SteadyState then
der(y) = 0;
elseif initType == Init.InitialState or initType == Init.InitialOutput then
y = y_start;
end if;
equation
der(y) = (k*u - y)/T;
annotation (
Documentation(info="<html>
<p>
This blocks defines the transfer function between the input u
and the output y as <em>first order</em> system:
</p>
<blockquote><pre>
k
y = ------------ * u
T * s + 1
</pre></blockquote>
<p>
If you would like to be able to change easily between different
transfer functions (FirstOrder, SecondOrder, ... ) by changing
parameters, use the general block <strong>TransferFunction</strong> instead
and model a first order SISO system with parameters<br>
b = {k}, a = {T, 1}.
</p>
<blockquote><pre>
Example:
parameter: k = 0.3, T = 0.4
results in:
0.3
y = ----------- * u
0.4 s + 1.0
</pre></blockquote>
</html>"), Icon(
coordinateSystem(preserveAspectRatio=true,
extent={{-100.0,-100.0},{100.0,100.0}}),
graphics={
Line(points={{-80.0,78.0},{-80.0,-90.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{-80.0,90.0},{-88.0,68.0},{-72.0,68.0},{-80.0,90.0}}),
Line(points={{-90.0,-80.0},{82.0,-80.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{90.0,-80.0},{68.0,-72.0},{68.0,-88.0},{90.0,-80.0}}),
Line(origin = {-26.667,6.667},
points = {{106.667,43.333},{-13.333,29.333},{-53.333,-86.667}},
color = {0,0,127},
smooth = Smooth.Bezier),
Text(textColor={192,192,192},
extent={{0.0,-60.0},{60.0,0.0}},
textString="PT1"),
Text(extent={{-150.0,-150.0},{150.0,-110.0}},
textString="T=%T")}));
end FirstOrder;
block SecondOrder "Second order transfer function block (= 2 poles)"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Gain";
parameter Real w(start=1) "Angular frequency";
parameter Real D(start=1) "Damping";
parameter Init initType=Init.NoInit
"Type of initialization (1: no init, 2: steady state, 3/4: initial output)" annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real y_start=0 "Initial or guess value of output (= state)"
annotation (Dialog(group="Initialization"));
parameter Real yd_start=0
"Initial or guess value of derivative of output (= state)"
annotation (Dialog(group="Initialization"));
extends Interfaces.SISO(y(start=y_start));
output Real yd(start=yd_start) "Derivative of y";
initial equation
if initType == Init.SteadyState then
der(y) = 0;
der(yd) = 0;
elseif initType == Init.InitialState or initType == Init.InitialOutput then
y = y_start;
yd = yd_start;
end if;
equation
der(y) = yd;
der(yd) = w*(w*(k*u - y) - 2*D*yd);
annotation (
Documentation(info="<html>
<p>
This blocks defines the transfer function between the input u and
the output y as <em>second order</em> system:
</p>
<blockquote><pre>
k
y = --------------------------------- * u
( s / w )^2 + 2*D*( s / w ) + 1
</pre></blockquote>
<p>
If you would like to be able to change easily between different
transfer functions (FirstOrder, SecondOrder, ... ) by changing
parameters, use the general model class <strong>TransferFunction</strong>
instead and model a second order SISO system with parameters<br>
b = {k}, a = {1/w^2, 2*D/w, 1}.
</p>
<blockquote><pre>
Example:
parameter: k = 0.3, w = 0.5, D = 0.4
results in:
0.3
y = ------------------- * u
4.0 s^2 + 1.6 s + 1
</pre></blockquote>
</html>"), Icon(
coordinateSystem(preserveAspectRatio=true,
extent={{-100.0,-100.0},{100.0,100.0}}),
graphics={
Line(points={{-80.0,78.0},{-80.0,-90.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{-80.0,90.0},{-88.0,68.0},{-72.0,68.0},{-80.0,90.0}}),
Line(points={{-90.0,-80.0},{82.0,-80.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{90.0,-80.0},{68.0,-72.0},{68.0,-88.0},{90.0,-80.0}}),
Line(origin = {-1.939,-1.816},
points = {{81.939,36.056},{65.362,36.056},{14.39,-26.199},{-29.966,113.485},{-65.374,-61.217},{-78.061,-78.184}},
color = {0,0,127},
smooth = Smooth.Bezier),
Text(textColor={192,192,192},
extent={{0.0,-70.0},{60.0,-10.0}},
textString="PT2"),
Text(extent={{-150.0,-150.0},{150.0,-110.0}},
textString="w=%w")}));
end SecondOrder;
block PI "Proportional-Integral controller"
import Modelica.Blocks.Types.Init;
parameter Real k=1 "Gain";
parameter SI.Time T(start=1,min=Modelica.Constants.small)
"Time Constant (T>0 required)";
parameter Init initType=Init.NoInit
"Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"
annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real x_start=0 "Initial or guess value of state"
annotation (Dialog(group="Initialization"));
parameter Real y_start=0 "Initial value of output"
annotation(Dialog(enable=initType == Init.SteadyState or initType == Init.InitialOutput, group=
"Initialization"));
extends Interfaces.SISO;
output Real x(start=x_start) "State of block";
initial equation
if initType == Init.SteadyState then
der(x) = 0;
elseif initType == Init.InitialState then
x = x_start;
elseif initType == Init.InitialOutput then
y = y_start;
end if;
equation
der(x) = u/T;
y = k*(x + u);
annotation (defaultComponentName="PI",
Documentation(info="<html>
<p>
This blocks defines the transfer function between the input u and
the output y as <em>PI</em> system:
</p>
<blockquote><pre>
1
y = k * (1 + ---) * u
T*s
T*s + 1
= k * ------- * u
T*s
</pre></blockquote>
<p>
If you would like to be able to change easily between different
transfer functions (FirstOrder, SecondOrder, ... ) by changing
parameters, use the general model class <strong>TransferFunction</strong>
instead and model a PI SISO system with parameters<br>
b = {k*T, k}, a = {T, 0}.
</p>
<blockquote><pre>
Example:
parameter: k = 0.3, T = 0.4
results in:
0.4 s + 1
y = 0.3 ----------- * u
0.4 s
</pre></blockquote>
<p>
It might be difficult to initialize the PI component in steady state
due to the integrator part.
This is discussed in the description of package
<a href=\"modelica://Modelica.Blocks.Continuous#info\">Continuous</a>.
</p>
</html>"), Icon(coordinateSystem(
preserveAspectRatio=true,
extent={{-100,-100},{100,100}}), graphics={
Line(points={{-80,78},{-80,-90}}, color={192,192,192}),
Polygon(
points={{-80,90},{-88,68},{-72,68},{-80,90}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points={{-90,-80},{82,-80}}, color={192,192,192}),
Polygon(
points={{90,-80},{68,-72},{68,-88},{90,-80}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points = {{-80.0,-80.0},{-80.0,-20.0},{60.0,80.0}}, color = {0,0,127}),
Text(
extent={{0,6},{60,-56}},
textColor={192,192,192},
textString="PI"),
Text(
extent={{-150,-150},{150,-110}},
textString="T=%T")}));
end PI;
block PID "PID-controller in additive description form"
import Modelica.Blocks.Types.Init;
extends Interfaces.SISO;
parameter Real k=1 "Gain";
parameter SI.Time Ti(min=Modelica.Constants.small, start=0.5)
"Time Constant of Integrator";
parameter SI.Time Td(min=0, start=0.1)
"Time Constant of Derivative block";
parameter Real Nd(min=Modelica.Constants.small) = 10
"The higher Nd, the more ideal the derivative block";
parameter Init initType= Init.InitialState
"Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"
annotation(Evaluate=true,
Dialog(group="Initialization"));
parameter Real xi_start=0
"Initial or guess value for integrator output (= integrator state)"
annotation (Dialog(group="Initialization"));
parameter Real xd_start=0
"Initial or guess value for state of derivative block"
annotation (Dialog(group="Initialization"));
parameter Real y_start=0 "Initial value of output"
annotation(Dialog(enable=initType == Init.InitialOutput, group=
"Initialization"));
constant SI.Time unitTime=1 annotation(HideResult=true);
Blocks.Math.Gain P(k=1) "Proportional part of PID controller"
annotation (Placement(transformation(extent={{-60,60},{-20,100}})));
Blocks.Continuous.Integrator I(k=unitTime/Ti, y_start=xi_start,
initType=if initType==Init.SteadyState then
Init.SteadyState else
if initType==Init.InitialState then
Init.InitialState else Init.NoInit)
"Integral part of PID controller"
annotation (Placement(transformation(extent={{-60,-20},{-20,20}})));
Blocks.Continuous.Derivative D(k=Td/unitTime, T=max([Td/Nd, 100*Modelica.
Constants.eps]), x_start=xd_start,
initType=if initType==Init.SteadyState or
initType==Init.InitialOutput then Init.SteadyState else
if initType==Init.InitialState then Init.InitialState else
Init.NoInit) "Derivative part of PID controller"
annotation (Placement(transformation(extent={{-60,-100},{-20,-60}})));
Blocks.Math.Gain Gain(k=k) "Gain of PID controller"
annotation (Placement(transformation(extent={{60,-10},{80,10}})));
Blocks.Math.Add3 Add annotation (Placement(transformation(extent={{20,-10},
{40,10}})));
initial equation
if initType==Init.InitialOutput then
y = y_start;
end if;
equation
connect(u, P.u) annotation (Line(points={{-120,0},{-80,0},{-80,80},{-64,80}}, color={0,0,127}));
connect(u, I.u)
annotation (Line(points={{-120,0},{-64,0}}, color={0,0,127}));
connect(u, D.u) annotation (Line(points={{-120,0},{-80,0},{-80,-80},{-64,-80}},
color={0,0,127}));
connect(P.y, Add.u1) annotation (Line(points={{-18,80},{0,80},{0,8},{18,8}}, color={0,0,127}));
connect(I.y, Add.u2)
annotation (Line(points={{-18,0},{18,0}}, color={0,0,127}));
connect(D.y, Add.u3) annotation (Line(points={{-18,-80},{0,-80},{0,-8},{18,-8}},
color={0,0,127}));
connect(Add.y, Gain.u)
annotation (Line(points={{41,0},{58,0}}, color={0,0,127}));
connect(Gain.y, y)
annotation (Line(points={{81,0},{110,0}}, color={0,0,127}));
annotation (defaultComponentName="PID",
Icon(
coordinateSystem(preserveAspectRatio=true,
extent={{-100.0,-100.0},{100.0,100.0}}),
graphics={
Line(points={{-80.0,78.0},{-80.0,-90.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{-80.0,90.0},{-88.0,68.0},{-72.0,68.0},{-80.0,90.0}}),
Line(points={{-90.0,-80.0},{82.0,-80.0}},
color={192,192,192}),
Polygon(lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid,
points={{90.0,-80.0},{68.0,-72.0},{68.0,-88.0},{90.0,-80.0}}),
Line(points = {{-80,-80},{-80,-20},{60,80}}, color = {0,0,127}),
Text(textColor={192,192,192},
extent={{-20.0,-60.0},{80.0,-20.0}},
textString="PID"),
Text(extent={{-150.0,-150.0},{150.0,-110.0}},
textString="Ti=%Ti")}),
Documentation(info="<html>
<p>
This is the text-book version of a PID-controller.
For a more practically useful PID-controller, use
block LimPID.
</p>
<p>
The PID block can be initialized in different
ways controlled by parameter <strong>initType</strong>. The possible
values of initType are defined in
<a href=\"modelica://Modelica.Blocks.Types.Init\">Modelica.Blocks.Types.Init</a>.
</p>
<p>
Based on the setting of initType, the integrator (I) and derivative (D)
blocks inside the PID controller are initialized according to the following table:
</p>
<table border=\"1\" cellspacing=\"0\" cellpadding=\"2\">
<tr><td><strong>initType</strong></td>
<td><strong>I.initType</strong></td>
<td><strong>D.initType</strong></td></tr>
<tr><td><strong>NoInit</strong></td>
<td>NoInit</td>
<td>NoInit</td></tr>
<tr><td><strong>SteadyState</strong></td>
<td>SteadyState</td>
<td>SteadyState</td></tr>
<tr><td><strong>InitialState</strong></td>
<td>InitialState</td>
<td>InitialState</td></tr>
<tr><td><strong>InitialOutput</strong><br>
and initial equation: y = y_start</td>
<td>NoInit</td>
<td>SteadyState</td></tr>
</table>
<p>
In many cases, the most useful initial condition is
<strong>SteadyState</strong> because initial transients are then no longer
present. If initType = Init.SteadyState, then in some
cases difficulties might occur. The reason is the
equation of the integrator:
</p>
<blockquote><pre>
<strong>der</strong>(y) = k*u;
</pre></blockquote>
<p>
The steady state equation \"der(x)=0\" leads to the condition that the input u to the
integrator is zero. If the input u is already (directly or indirectly) defined
by another initial condition, then the initialization problem is <strong>singular</strong>
(has none or infinitely many solutions). This situation occurs often
for mechanical systems, where, e.g., u = desiredSpeed - measuredSpeed and
since speed is both a state and a derivative, it is natural to
initialize it with zero. As sketched this is, however, not possible.
The solution is to not initialize u or the variable that is used
to compute u by an algebraic equation.
</p>
</html>"));
end PID;
block LimPID
"P, PI, PD, and PID controller with limited output, anti-windup compensation, setpoint weighting and optional feed-forward"
import Modelica.Blocks.Types.Init;
import Modelica.Blocks.Types.SimpleController;
extends Modelica.Blocks.Interfaces.SVcontrol;
output Real controlError = u_s - u_m
"Control error (set point - measurement)";
parameter .Modelica.Blocks.Types.SimpleController controllerType=
.Modelica.Blocks.Types.SimpleController.PID "Type of controller";
parameter Real k = 1 "Gain of controller, must be non-zero";
parameter SI.Time Ti(min=Modelica.Constants.small)=0.5
"Time constant of Integrator block" annotation (Dialog(enable=
controllerType == .Modelica.Blocks.Types.SimpleController.PI or
controllerType == .Modelica.Blocks.Types.SimpleController.PID));
parameter SI.Time Td(min=0)=0.1
"Time constant of Derivative block" annotation (Dialog(enable=
controllerType == .Modelica.Blocks.Types.SimpleController.PD or
controllerType == .Modelica.Blocks.Types.SimpleController.PID));
parameter Real yMax(start=1) "Upper limit of output";
parameter Real yMin=-yMax "Lower limit of output";
parameter Real wp(min=0) = 1
"Set-point weight for Proportional block (0..1)";
parameter Real wd(min=0) = 0 "Set-point weight for Derivative block (0..1)"
annotation(Dialog(enable=controllerType==.Modelica.Blocks.Types.SimpleController.PD or
controllerType==.Modelica.Blocks.Types.SimpleController.PID));
parameter Real Ni(min=100*Modelica.Constants.eps) = 0.9
"Ni*Ti is time constant of anti-windup compensation"
annotation(Dialog(enable=controllerType==.Modelica.Blocks.Types.SimpleController.PI or
controllerType==.Modelica.Blocks.Types.SimpleController.PID));
parameter Real Nd(min=100*Modelica.Constants.eps) = 10
"The higher Nd, the more ideal the derivative block"
annotation(Dialog(enable=controllerType==.Modelica.Blocks.Types.SimpleController.PD or
controllerType==.Modelica.Blocks.Types.SimpleController.PID));
parameter Boolean withFeedForward=false "Use feed-forward input?"
annotation(Evaluate=true, choices(checkBox=true));
parameter Real kFF=1 "Gain of feed-forward input"
annotation(Dialog(enable=withFeedForward));
parameter Init initType = Init.InitialState
"Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)"
annotation(Evaluate=true, Dialog(group="Initialization"));
parameter Real xi_start=0
"Initial or guess value for integrator output (= integrator state)"
annotation (Dialog(group="Initialization",
enable=controllerType==.Modelica.Blocks.Types.SimpleController.PI or
controllerType==.Modelica.Blocks.Types.SimpleController.PID));
parameter Real xd_start=0
"Initial or guess value for state of derivative block"
annotation (Dialog(group="Initialization",
enable=controllerType==.Modelica.Blocks.Types.SimpleController.PD or
controllerType==.Modelica.Blocks.Types.SimpleController.PID));
parameter Real y_start=0 "Initial value of output"
annotation(Dialog(enable=initType == Init.InitialOutput, group=
"Initialization"));
parameter Modelica.Blocks.Types.LimiterHomotopy homotopyType = Modelica.Blocks.Types.LimiterHomotopy.Linear
"Simplified model for homotopy-based initialization"
annotation (Evaluate=true, Dialog(group="Initialization"));
parameter Boolean strict=false "= true, if strict limits with noEvent(..)"
annotation (Evaluate=true, choices(checkBox=true), Dialog(tab="Advanced"));
constant SI.Time unitTime=1 annotation (HideResult=true);
Modelica.Blocks.Interfaces.RealInput u_ff if withFeedForward
"Optional connector of feed-forward input signal"
annotation (Placement(
transformation(
origin={60,-120},
extent={{20,-20},{-20,20}},
rotation=270)));
Modelica.Blocks.Math.Add addP(k1=wp, k2=-1)
annotation (Placement(transformation(extent={{-80,40},{-60,60}})));
Modelica.Blocks.Math.Add addD(k1=wd, k2=-1) if with_D
annotation (Placement(transformation(extent={{-80,-10},{-60,10}})));
Modelica.Blocks.Math.Gain P(k=1)
annotation (Placement(transformation(extent={{-50,40},{-30,60}})));
Modelica.Blocks.Continuous.Integrator I(
k=unitTime/Ti,
y_start=xi_start,
initType=if initType == Init.SteadyState then Init.SteadyState else if
initType == Init.InitialState
then Init.InitialState else Init.NoInit) if with_I
annotation (Placement(transformation(extent={{-50,-60},{-30,-40}})));
Modelica.Blocks.Continuous.Derivative D(
k=Td/unitTime,
T=max([Td/Nd,1.e-14]),
x_start=xd_start,
initType=if initType == Init.SteadyState or initType == Init.InitialOutput
then Init.SteadyState else if initType == Init.InitialState then
Init.InitialState else Init.NoInit) if with_D
annotation (Placement(transformation(extent={{-50,-10},{-30,10}})));
Modelica.Blocks.Math.Gain gainPID(k=k)
annotation (Placement(transformation(extent={{20,-10},{40,10}})));
Modelica.Blocks.Math.Add3 addPID
annotation (Placement(transformation(extent={{-10,-10},{10,10}})));
Modelica.Blocks.Math.Add3 addI(k2=-1) if with_I
annotation (Placement(transformation(extent={{-80,-60},{-60,-40}})));
Modelica.Blocks.Math.Add addSat(k1=+1, k2=-1) if with_I annotation (Placement(
transformation(
origin={80,-50},
extent={{-10,-10},{10,10}},
rotation=270)));
Modelica.Blocks.Math.Gain gainTrack(k=1/(k*Ni)) if with_I
annotation (Placement(transformation(extent={{0,-80},{-20,-60}})));
Modelica.Blocks.Nonlinear.Limiter limiter(
uMax=yMax,
uMin=yMin,
strict=strict,
homotopyType=homotopyType)
annotation (Placement(transformation(extent={{70,-10},{90,10}})));
protected
parameter Boolean with_I = controllerType==SimpleController.PI or
controllerType==SimpleController.PID annotation(Evaluate=true, HideResult=true);
parameter Boolean with_D = controllerType==SimpleController.PD or
controllerType==SimpleController.PID annotation(Evaluate=true, HideResult=true);
public
Modelica.Blocks.Sources.Constant Dzero(k=0) if not with_D
annotation (Placement(transformation(extent={{-40,20},{-30,30}})));
Modelica.Blocks.Sources.Constant Izero(k=0) if not with_I
annotation (Placement(transformation(extent={{0,-55},{-10,-45}})));
Modelica.Blocks.Sources.Constant FFzero(k=0) if not withFeedForward
annotation (Placement(transformation(extent={{30,-35},{40,-25}})));
Modelica.Blocks.Math.Add addFF(k1=1, k2=kFF)
annotation (Placement(transformation(extent={{48,-6},{60,6}})));
initial equation
if initType==Init.InitialOutput then
gainPID.y = y_start;
end if;
equation
assert(abs(k) >= Constants.small, "Controller gain must be non-zero.");
if initType == Init.InitialOutput and (y_start < yMin or y_start > yMax) then
Modelica.Utilities.Streams.error("LimPID: Start value y_start (=" + String(y_start) +
") is outside of the limits of yMin (=" + String(yMin) +") and yMax (=" + String(yMax) + ")");
end if;
connect(u_s, addP.u1) annotation (Line(points={{-120,0},{-96,0},{-96,56},{
-82,56}}, color={0,0,127}));
connect(u_s, addD.u1) annotation (Line(points={{-120,0},{-96,0},{-96,6},{
-82,6}}, color={0,0,127}));
connect(u_s, addI.u1) annotation (Line(points={{-120,0},{-96,0},{-96,-42},{
-82,-42}}, color={0,0,127}));
connect(addP.y, P.u) annotation (Line(points={{-59,50},{-52,50}}, color={0,
0,127}));
connect(addD.y, D.u)
annotation (Line(points={{-59,0},{-52,0}}, color={0,0,127}));
connect(addI.y, I.u) annotation (Line(points={{-59,-50},{-52,-50}}, color={
0,0,127}));
connect(P.y, addPID.u1) annotation (Line(points={{-29,50},{-20,50},{-20,8},{-12,
8}}, color={0,0,127}));
connect(D.y, addPID.u2)
annotation (Line(points={{-29,0},{-12,0}},color={0,0,127}));
connect(I.y, addPID.u3) annotation (Line(points={{-29,-50},{-20,-50},{-20,-8},
{-12,-8}}, color={0,0,127}));
connect(limiter.y, addSat.u1) annotation (Line(points={{91,0},{94,0},{94,
-20},{86,-20},{86,-38}}, color={0,0,127}));
connect(limiter.y, y)
annotation (Line(points={{91,0},{110,0}}, color={0,0,127}));
connect(addSat.y, gainTrack.u) annotation (Line(points={{80,-61},{80,-70},{2,-70}},
color={0,0,127}));
connect(gainTrack.y, addI.u3) annotation (Line(points={{-21,-70},{-88,-70},{-88,
-58},{-82,-58}}, color={0,0,127}));
connect(u_m, addP.u2) annotation (Line(points={{0,-120},{0,-92},{-92,-92},{-92,44},{-82,44}}, color={0,0,127}));
connect(u_m, addD.u2) annotation (Line(points={{0,-120},{0,-92},{-92,-92},{-92,-6},{-82,-6}}, color={0,0,127}));
connect(u_m, addI.u2) annotation (Line(points={{0,-120},{0,-92},{-92,-92},{-92,-50},{-82,-50}}, color={0,0,127}));
connect(Dzero.y, addPID.u2) annotation (Line(points={{-29.5,25},{-24,25},{-24,
0},{-12,0}}, color={0,0,127}));
connect(Izero.y, addPID.u3) annotation (Line(points={{-10.5,-50},{-20,-50},{-20,
-8},{-12,-8}}, color={0,0,127}));
connect(addPID.y, gainPID.u)
annotation (Line(points={{11,0},{18,0}}, color={0,0,127}));
connect(addFF.y, limiter.u)
annotation (Line(points={{60.6,0},{68,0}}, color={0,0,127}));
connect(gainPID.y, addFF.u1) annotation (Line(points={{41,0},{44,0},{44,3.6},
{46.8,3.6}},color={0,0,127}));
connect(FFzero.y, addFF.u2) annotation (Line(points={{40.5,-30},{44,-30},{44,
-3.6},{46.8,-3.6}},
color={0,0,127}));
connect(addFF.u2, u_ff) annotation (Line(points={{46.8,-3.6},{44,-3.6},{44,
-92},{60,-92},{60,-120}},
color={0,0,127}));
connect(addFF.y, addSat.u2) annotation (Line(points={{60.6,0},{64,0},{64,-20},
{74,-20},{74,-38}}, color={0,0,127}));
annotation (defaultComponentName="PID",
Icon(coordinateSystem(
preserveAspectRatio=true,
extent={{-100,-100},{100,100}}), graphics={
Line(points={{-80,78},{-80,-90}}, color={192,192,192}),
Polygon(
points={{-80,90},{-88,68},{-72,68},{-80,90}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points={{-90,-80},{82,-80}}, color={192,192,192}),
Polygon(
points={{90,-80},{68,-72},{68,-88},{90,-80}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points={{-80,-80},{-80,-20},{30,60},{80,60}}, color={0,0,127}),
Text(
extent={{-20,-20},{80,-60}},
textColor={192,192,192},
textString="%controllerType"),
Line(
visible=strict,
points={{30,60},{81,60}},
color={255,0,0})}),
Diagram(graphics={Text(
extent={{79,-112},{129,-102}},
textColor={0,0,255},
textString=" (feed-forward)")}),
Documentation(info="<html>
<p>
Via parameter <strong>controllerType</strong> either <strong>P</strong>, <strong>PI</strong>, <strong>PD</strong>,
or <strong>PID</strong> can be selected. If, e.g., PI is selected, all components belonging to the
D-part are removed from the block (via conditional declarations).
The example model
<a href=\"modelica://Modelica.Blocks.Examples.PID_Controller\">Modelica.Blocks.Examples.PID_Controller</a>
demonstrates the usage of this controller.
Several practical aspects of PID controller design are incorporated
according to chapter 3 of the book:
</p>
<dl>
<dt>Åström K.J., and Hägglund T.:</dt>
<dd> <strong>PID Controllers: Theory, Design, and Tuning</strong>.
Instrument Society of America, 2nd edition, 1995.
</dd>
</dl>
<p>
Besides the additive <strong>proportional, integral</strong> and <strong>derivative</strong>
part of this controller, the following features are present:
</p>
<ul>
<li> The output of this controller is limited. If the controller is
in its limits, anti-windup compensation is activated to drive
the integrator state to zero.</li>
<li> The high-frequency gain of the derivative part is limited
to avoid excessive amplification of measurement noise.</li>
<li> Setpoint weighting is present, which allows to weight
the setpoint in the proportional and the derivative part
independently from the measurement. The controller will respond
to load disturbances and measurement noise independently of this setting
(parameters wp, wd). However, setpoint changes will depend on this
setting. For example, it is useful to set the setpoint weight wd