Assistance with Modified Thermal XML Model for Parallel IGBT Modules

Dear PLECS Support Team

I have developed an AFE converter model that, in reality, uses the 6 Infineon FS450R17OE4 IGBT module. Due to the high current, each switching position consists of six identical IGBT modules connected in parallel.

When I model all six modules individually using their thermal models, the simulation becomes significantly slower. Therefore, I tried to create an equivalent thermal model by modifying the XML file of a single module so that it represents the six parallel modules.

The modifications I made include:

  • Scaling the conduction and switching losses to represent the total losses of the six parallel modules.

  • Adjusting the thermal model by dividing the thermal resistances by six while keeping the thermal time constants unchanged.

However, after making these modifications, PLECS reports the following error:

“Unexpected feedback during calculation of switch losses.”

I have attached:

  • the original XML file,

  • the modified XML file, and

  • a screenshot of the error message.

Could you please help me understand what is causing this error? In particular, I would like to know whether my approach for creating an equivalent thermal model is correct, and whether there are any restrictions on modifying the switching-loss formulas in the XML file.

Thank you very much for your time and assistance.

Kind regards

Milan Van de Walle

FS450R17OE4_switch_modification_to_1.xml (15.6 KB)

FS450R17OE4_switch.xml (15.5 KB)