I want to simulate an inverter topology using PSIM thermal module to calculate MOSFET switching and conduction losses at different power levels. How I can adjust different power levels in grid-connected inverter topology (for example 100%, 75%, 50%, 25% of total power) and calculate losses at each level?
What sort of load are you looking to use? The easiest thing to do is to use a parameter file and define and R and an L value for an RL load. Then simply define the desired VA and PF and then split those apart into the correct R+jX values you need. The equations can be defined in the parameter file so that you just input the VA and PF and the R and L jump out at the bottom.
First you need to swap in the actual thermal devices from the database and not use the base ideal switches.
2nd) You would be well advised to write a script, please consult the examples\script folder and tutorial for the script functions in help->tutorials. The script will be able to change the load for you and compile results while you have a coffee.