OpenModelica: “Warning: maximal number of iteration reached but no root found” with conditional equation

Question

I am an OpenModelica beginner trying to model a DC/DC converter with constant voltage and current limiting. Basically the output is supposed to give a constant voltage until the

Answer 1

Unfortunately you have to learn about s-parametrization to solve this, as is found in e.g. Modelica.Electrical.Analog.Ideal.IdealDiode.

Except for unit-checking you should do something like:

 Real s;
equation 

  v = p.v - n.v;

  if s<0 then
    s=v-Vnom;
    n.i=Imax;
  else
    Vnom = v;
    s=Imax-n.i;
  end if;
  0 = p.i + n.i;

I believe the original reference for this is https://ieeexplore.ieee.org/document/808640

This model can also be rewritten sin this style by adding a new variable and rewriting the if-equations

  Boolean saturatedCurrent=s<0;
equation
  v-vNom=if saturatedCurrent then s else 0;
  Imax-n.i=if saturatedCurrent then 0 else s;