Hello everyone,

How does PLECS thermal look-up models calculate losses? As the MOSFETs/IGBTs are switched with ideal waveforms, the effect of the output capacitance on the switching is not seen. Also the current waveforms are quite ideal in these cases.

My guess is that the thermal model basically checks the current and voltage at switching instant and calculates the losses based on the loop-up table. In that cases, how accurate are the losses calculated? Should they be strictly used for estimating purposes?

Thank you.

Thank you for your answer. I have accurate data from the manufacturers. So based on the current/votlage values during switching, I have the right losses.

My question now is that if my waveforms are ideal, without dead-time and output capacitance variation, the shape of current waveform and its value at the switching instant will not be the same as the intra/extrapolated value. In my simulation of the DC-DC converter, the value of magnetizing current should determine if the MOSFETs hard-switch or not. But if there are no non-linear output capacitors across my MOSFET; my waveforms would be ideal and the switching losses from the thermal model would be wrong. Am I missing something?

Pramod