Modeling non-linear FET drain capacitance

I’m trying to simulate a DC-DC transformer that operates with resonant transitions, similar to a phase-shifted full bridge design.

The FETs are super-junction types with very non-linear drain capacitance. The shape of the resonant transition affects the transfer characteristics of the circuit so it’s important to model this capacitance. Ideal switches won’t work.

I have done this in SPICE with Infineon’s models, but it doesn’t seem possible to accurately simulate resonant circuits with non-linear capacitance, in PSIM.

Also, the FET body diode recovery similarly affects the operation of the circuit but how to model it?

HI Jeff,

Please email me directly adunford at the domain of our website. I have a beta non-linear cap model that might be of interest.

Also, you can have a look at this tutorial video in the meantime which also might be of interest.

https://youtu.be/iATO3mUKBPc - level 2 model in PSIM of SiC FET

-Albert