I found the igbt and freewheel were much happier at 8khz. My igbt is '05 vintage ex vfd. It did run at 16khz but i had problems with ringing at turn off. I just got an email from fran with v1.4 that , while untested , generates a 8khz pwm while running at 16mhz! Now I have the fun prospect of changing the crystal back to 16mhz while still in the car
That said i'm building up another control board so may test it on that first. I'm running v0.9 in the car with great results i'd just like to be able to use newer versions of the code as it evolves. I don't know how or if the lower frequency would effect the mosfet design but mabey someone could run a test?