So now we have a thermal simulation for inverter. Sauna is the program I used for the model. It is a relatively inexpensive package that I have used for many years. When I was a young engineer these tools were not generally available . It would take a whole day to crunch the numbers to design a heatsink. Now it takes less than an hour to run models and what-if type changes to the heatsink can be made on the fly. This allows converging to a solution in a very short time.
So what does this simulation tell us? The simulation tells us that the junction temperature is 123c at 5kW output. This is a very reasonable number but there is little overload capability left. Suppose the specification is 5kW continuous with a 100% overload. We could parallel two of these inverters to get to 10kW or put two in series for a 240v split phase system. Next we will look at a forced air solution. This will allow a much smaller package volume. We can also look at running switches with IGBTs and SiC fets.
