PLECS does not provide a library of manufacturer-specific models. Instead, the user is able to create their own thermal descriptions (switching and conduction loss data tables and the junction-case thermal impedance characteristic) for any power semiconductor or module of their choosing. The "Manufacturer" field in the PLECS Thermal Editor is available simply for documentation purposes.
Having said that, there are a number of power semiconductor manufacturers that provide the .XML files for their devices to be used in PLECS directly, including Infineon. If you search on www.infineon.com for "Simulation Model - PLECS Discrete IGBT Library", for example, you will be able to download a set of component models today, and more of their catalog will be supported in the near future.
You can find instructions on how to then include these thermal description files in your simulation model in our documentation.
I hope this helps!