Zero switching losses

General
1

I am simulating the losses in an inverter module. During the staring of the simulation there is some switching losses but around after the half simulation duration the switching loss goes to zero. How can I get the switching losses? Or is the issue due to the lack of thermal description data for low voltage values?

Gesamt_Modell_Control.m (6.5 KB)
upload.slx (433.3 KB)

2

This is due to the data in the thermal descriptions. I’m not sure if we have the same version of the Navitas/GeneSic thermal description files, but I will describe how my models look.

For the GD50MPS12H Diode I only see conduction loss data with zero turn-on and turn-off losses in the model. Only conduction losses are modeled.

For the G3R40MT12K SiC MOSFETs there is turn-on and turn-off data. I noted that there are turn-on losses but zero turn-off losses. The reason is that the devices are turning off with negative current. The look-up tables do not define loss values when they turn off with negative current and so the losses are zero.

3

Hey, thanks for the response.

So, is there any way to calculate the switching losses via PLECS?

Thanks in advance.

4

Yes, PLECS can calculate switching losses when the necessary data is included in the provided thermal model. There are previous forum posts that describe a formula based approach based on datasheet parameters, but note the caveats there (such as the lack of temperature dependency included in the formulas).

The datasheets for those devices include the relevant constants, but don’t contain additional switching loss information in graphical format - for example losses for 3rd quadrant turn-off. However, in those cases perhaps the losses are small enough to be considered negligible by the vendor.