Under-determined linear system not solvable!

[Christian Kral <dr.christian.kral@…>]

I noticed that the simulation of one the following examples in Modelica_Electrical_PowerConverters.Examples.ACDC.ThyristorBridge2mPulse

1. ThyristorBridge2mPulse_R
2. ThyristorBridge2mPulse_RL
3. ThyristorBridge2mPulse_RLV
4. ThyristorBridge2mPulse_RLV_Characteristic
5. ThyristorBridge2mPulse_DC_Drive

causes multiple error messages of the kind:

under-determined linear system not solvable!
Matrix singular!

The first three examples at least simulate, even though these error messages occur. Example 4 takes too long to wait for the simulation to end. Example 5 does not finish simulation at all.

I have to note, however, that these examples have been working in previous versions of OpenModelica. The actual bug report refers to

• Ubuntu 14.04 32 bit
• OpenModelica r24056
• Library Modelica_Electrical_PowerConverters located on ​https://svn.modelica.org/projects/Modelica_ElectricalSystems/Modelica_Electrical_PowerConverters/branches/Modelica_Electrical_PowerConverters%203.2.1; a modified version of this library is planned to be included in MSL 3.2.2

I am not sure whether this ticket is related with #2996 or not.

[Christian Kral <dr.christian.kral@…>]

Quick update: I just checked the issue under Debian Wheezy 64 bit with OMEdit r23888. Examples 1-4 now simulate without problems; example 5 fails with the same error as mentioned above.

[wbraun]

All of the samples 1-5 are working currently, but example 4-5 are really slow.
It seems that there is a non-linear algebraic loop, which is currently linear.