Which is the most accurate way to simulate/calculate the efficiency of power electronics?

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I’m trying to simulate the efficiency of an IGBT driven power module. With Pin=Pout+Ploss, the efficiency could be calculated as:

eta=Pout/Pin    eta=1-Ploss/PinAs you can see in the model attached, I tried both ways with different models. At first using an ideal switch, then an IGBT with linear loss model (Vf and Ron), then with a thermal description, and finally with both combined. The maximum difference between calculated accuracies is about 1%, which is quite a bit.

So my question is: Which of the described ways is most accurate one?

Thanks in advance

Fabian

Efficiency.plecs (65 KB)

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Hi Fabian,

The second formula is the one to take. One reason for example why they give different results is that the switching losses are not withdrawn from the circuit as PLECS treats switching transitions as ideal. This means Pout calculated from electrical quantities in the circuit is generally different from the term Pin-Ploss, where Ploss is calculated from thermal descriptions.I hope this helps you.Best regards,NF