A common question regarding the thermal model is if it allows for soft switching simulations. In this article, we’ll take a look at how soft switching works with thermal models.
If you want to know how PSIM calculates and scales losses with temperature, voltage, current and Rg, please take a look at this article:
Altair Community - How Curves Are Used to Calculate Losses in the Thermal Module
Measurements for switching loss calculations
First we need to understand what information PSIM uses to calculate losses, specifically the datapoints being sampled.
At turn on, PSIM measures the last voltage data point from the off state along with the first current data point of the on state. The complementary idea happens in turn off.
In the case of soft switching, the voltage/current across/through the device during turn on/off is close to zero. In those cases, these values will be measured and used for loss calculation which results in lower losses. We can see this effect in the following image where we compare two switching cycles and their losses:
Attached to this discussion you'll find the schematic we used to get these plots. In the parameter file, you can change the on/off time to see these effects yourself.
Feel free to reach out to support if you have further questions.
