Connection Equations

In Modelica we use connect equations to establish connections between components via connectors. The two arguments of a connect equation must be references to connectors, each of which either has to be declared directly within the same class where the connect equation occurs, or has to be a member of one of the declared variables in that class. The ResistorCircuit fulfills the locality constraint mentioned above.

model ResistorCircuit Modelica.Electrical.Analog.Basic.Resistor R1(R = 100); Modelica.Electrical.Analog.Basic.Resistor R2(R = 200); Modelica.Electrical.Analog.Basic.Resistor R3(R = 300); equation connect(R1.p, R2.p); connect(R1.p, R3.p); end ResistorCircuit;

1 Repetitive Connection Structures

You can use connect equations together with the for-equation construct described previously to establish repetitive connection structures consisting of a number of connections between connectors belonging to array elements. This is a quite important use of for-equations in combination with connect equations.

class RegComponent parameter Integer n; //Modelica.Electrical.Analog.Basic.Resistor[n] r_components (each R=3) //We can replace the next line with the previous line if we want to //have the same resistance in all the resistors. Otherwise we can //manually put it in a vector like the one below. Modelica.Electrical.Analog.Basic.Resistor[n]r_components(R={1,2,3,4,5,6}); Modelica.Electrical.Analog.Basic.Capacitor C(C = 1, v(fixed = true)); Modelica.Electrical.Analog.Basic.Ground G; Modelica.Electrical.Analog.Sources.SineVoltage src(V=10, freqHz = 50); equation for i in 1:n-1 loop connect(r_components[i].n, r_components[i + 1].p); end for; connect(G.p,C.n); connect(C.p,r_components[n].n); connect(r_components[1].p,src.p); connect(src.n,G.p); end RegComponent;
model Test RegComponent rc(n = 6); end Test;
loadModel(Modelica)

2 Simulation of Test

simulate( Test )
plot(rc.n)