Modelica.Electrical.Spice3.Examples.CascodeCircuit

[Jens Frenkel]

The model Modelica.Electrical.Spice3.Examples.CascodeCircuit fails in simulation because the equations

4/8 (1): J1.icGD = J1.cc.cGD * der(J1.vGD)
5/9 (1): J1.icGS = J1.cc.cGS * der(J1.vGS)
13/21 (1): J2.icGD = J2.cc.cGD * der(J2.vGD)
14/22 (1): J2.icGS = J2.cc.cGS * der(J2.vGS)

are not solvable for the der(...) variables because J*.cc.cGD is zero.

If you take a look at the equation

22/30 (1): J2.vGS = v_sin.VO + (if time < v_sin.TD then 0.0 else v_sin.VA * exp((v_sin.TD - time) * v_sin.THETA) * sin(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)))

you see that the state candidate J2.vGS is the only unkown variable in the equation. Hence the variable J2.vGS is purely algebraic and the variable der(J2.vGS) is known as

der(J2.vGS) = if time < v_sin.TD then 0.0 else v_sin.VA * (exp((v_sin.TD - time) * v_sin.THETA) * 6.283185307179586 * v_sin.FREQ * cos(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)) + (-v_sin.THETA) * exp((v_sin.TD - time) * v_sin.THETA) * sin(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)))

Subsequently the variable J2.igsgmin is known from equation

15/23 (1): J2.igsgmin = 0.000000000001 * J2.vGS

and should be used to calculate the state candidates J1.vGS, J1.vGD and J2.vGD with the equations

6/10 (1): J1.igsgmin = 0.000000000001 * J1.vGS
7/11 (1): J1.igdgmin = 0.000000000001 * J1.vGD
16/24 (1): J2.igdgmin = 0.000000000001 * J2.vGD

Finally all state candidates are algebraic variables and the model is solvable.