I'm just asking, because the only experience i have with pwm are driving a couple of Mosfets via a mosfet-driver; driving a dumpload of 28A. I had no experience with mosfet/pwm, and getting the mosfets happy was a challenge... It all came down to the driver and the pcb design. In the beginning, i drove the mosfets directly from the pic output; it worked, but the mosfet was getting terrible hot, even with low loads, and the scope pic was terrible.
After burning up 5-6 drivers (which are cmos devices; d*mn sensitive buggers...), i finally got it right; i even added ferrite beads on the gate resistors etc., and now the fets are running lukewarm @ 28A; max load: 100A+. (2x IRFZ48) The scope pic are now square as a cube; both at the gate and the drain.
In the beginning i ran @ 16kHz, which seems fine at the moment (without driver circuit), but in my quest to reduce heat in the mosfets (still without driver), i ended up with 4kHz; that's what i'm still running, but i'm seriously thinking on changing it to 20kHz++, because when the dumpload are active, some of my led-lights are humming with a VERY irritating 4kHz noise!
Though; with a gasoline gen running, charging a battery, that wouldn't be a problem. And heat in a transistor usually rises a bit with higher frequencies...
Now, that was a bit of a rant... Sorry...