How to establish thermal models for electrolytic capacitors and MLCC capacitors in PLECS, and simulate junction temperature and ripple current.
Hi ssq,
The PLECS capacitor is an ideal component and therefore does not produce any losses. As a result, placing the capacitor on a thermal heat sink will not contribute to thermal losses in your simulation.
However, you can model the capacitor’s ESR using a resistor. The resulting I²R losses in the resistor will be dissipated into the thermal heat sink and contribute to the temperature rise of the component. To accurately capture this, you will also need to model the thermal impedance of the capacitor.
Note that this lumped ESR model is not frequency dependent. If you need to account for frequency-dependent losses, one approach is to measure the capacitor current using an ammeter. You can then use the controls domain to calculate the frequency-dependent losses and feed that losses into the thermal model using the PLECS Controlled Heat Flow component.
Hope this helps!