Hello,
Actually, the Heat Sink component is required for doing a simulation that includes thermal calculations in PLECS. It is an isothermal surface of equal temperature that captures losses from switch and resistive components within its borders. This block can represent an actual heat sink in your system or the case of a semiconductor, for example, depending on how you define the rest of the circuit. You might find our tutorial videos on the thermal domain helpful: https://www.plexim.com/support/videos
Best regards,
Kris
