Error in the parallel connection of voltage generators (cells)

Question

I am having the following errors during the simulation of the model in the picture (the blocks cell, cell1, and cell2 contains the electrochemical model of a battery cell, by the way also trying to change these blocks with the built-in ConstantVoltage I got a similar error):

[1] 12:36:28 Symbolic Error An independent subset of the model has imbalanced number of equations (180) and variables (177). variables:

[2] 12:36:37 Translation Error pre-optimization module clockPartitioning (simulation) failed.

Do you know what is the reason of this error?

Answer 1

I notice two things:

1. All voltage sources are short-cirquited which gives contradictory equations (v=V and v=0). The variable names refer to the code of Modelica.Electrical.Analog.Sources.ConstantVoltage
2. The parallel voltage sources each try to set the voltage across the parallel sources.

Answer 2

It is not possible to connect

1. ideal sources of potential variables (in this case voltages) in parallel or
2. ideal sources of flow (could be current sources) in series.

For the circuit in the screenshot, this will result in equation systems cell.V = cell.V1 = cell.V2 with all of the variables known and therefore resulting in an "imbalanced number of equations and variables.

What you need to do is make the sources non-ideal, which usually is closer to reality. For this you can e.g. add a inner resistance in series to all voltage sources. For current/flow sources this could be adding a parallel resistance to the source.

By the way: there is no point in connecting ideal voltage source in parallel, as each of them can supply infinite current without any drop in voltage...