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Calculating switching loss in MOSFET with Diode with vendor thermal description (GaN Systems)

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I'm trying to model semiconductor loss from a Gallium Nitride (GaN) MOSFET device. The device is modeled with Plecs MOSFET with Diode library model. The device thermal description is from GaN systems (a Plecs supported vendor) copied to a folder in same directory as simulation file following the folder naming convention (filename_plecs)

I can see the vendor thermal description in the Thermal Library Browser but I cannot assign it to the Plecs part. The From Library option in the thermal description is greyed out. I'm not sure why I cannot point the thermal description from the vendor to the Plecs library part. I swapped out MOSFET with Diode with MOSFET library part, same result. I looked at Plecs demo models, and there was nothing similar to my situation - the demo models have IGBT or MOSFET with separate thermal description files for Switch and Diode.

I'm looking for a Plecs reference implementation that uses Gallium Nitride (GaN) vendor thermal description paired with the Plecs Switching Loss calculation block. Or some documentation to figure out what is missing from the default library parts that is preventing their use with thermal description.

I have attached a bare-bones sim here for review.

asked Apr 10 by pchannegowda (35 points)
edited Apr 11 by pchannegowda

1 Answer

+1 vote
Best answer

Thermal description fields in PLECS components contain a filter such that they can only be associated with thermal descriptions associated with that component type.

Rather than distributing individual thermal descriptions (*.xml files) GaN Systems and other vendors are starting to distribute their models as Thermal Library Packages.  A thermal library package includes a *.plecs file with switch models that go into your PLECS library window, along with a set of *.xml files.  A nice advantage of this approach is that vendors can modify the electrical model based on data contained within a *.xml description (e.g. Vf, Ron, etc.).

When you visit GaN System's website you'll download a *.zip containing all the required info, which for GaN Systems models extracts a folder titled "gan_systems_plecs_models". To install the GaN Systems HEMT library component and corresponding thermal descriptions, simply add the directory containing the folder into the list of thermal description search paths in the Thermal tab of the PLECS Preferences window.  For example, if you have the following folder structure - ./my_plecs_thermal_library/gan_systems_plecs_models - you would refer to ./my_plecs_thermal_library in the PLECS Preferences window.

After refreshing you will see the "GaN Systems HEMT" component in the PLECS library window.  You can then associate the thermal description with that device.

answered Apr 11 by Bryan Lieblick (1,937 points)
selected Apr 11 by pchannegowda
Thanks Brian for the quick response! Your instructions solved my issue!

 BTW, the zip file from GaN systems includes an Install.txt file with the same instructions that you described above, I overlooked this file in my previous attempt.

Follow on question -  is it essential to follow these instructions and edit the Thermal description path in Plecs preferences to add this new component to Plecs Library? If I copy the component.plecs file to the folder named filename_plecs in the same directory as the sim file, can I automatically access this library part without editing the Thermal description path?

Plecs Standalone 4.8.2, 1e292bdb, win64 crashes when I link the thermal description to the Gan Systems HEMT device.

I have added gan_systems_plecs_models_030823 to the Thermal Description path in Plecs Preferences. I am using the library component GanSystemsHEMTComponent.plecs in my sim model. The model runs without errors when I use the HEMT component part in my model, but when I link the Thermal Description to the library part, Plecs crashes.

I have reported the problem to Plecs and provided the dump file at time of crash. Not sure if the dump file was sent, so I'm attaching it here.