[Shifty]

I have built some PWM controllers that used parallel MOSFETs but this can get you in to trouble rather quickly. Timing is absolutely critical. If one FET turns on just a few microseconds before the rest it will experience a large current surge through it. Also there is the issue of driving all that gate capacitance. You need to quickly get the FETs from the off state to the saturated fully on state. Power loss and therefore heat generation are real problems when in between states. My bet is that using an IGBT may be the best way to go for the real large stuff. I have a broken IGBT to show students that can supply 300 amps.