How do I turn on a mosfet just enough so the output is 13 amps for continious operation?
Datasheet says, Mosfet STW13NB60 is rate 500 volts, 13 continious amps. I want the mosfet to be able to run for 8 hours and not over heat. 13 amps may need to be reduced to a current that allows the mosfet to run for hours and not over heat.
My idea is to use 120 vac directly from the wall outlet. After the bridge rectifier and the filters capacitor 120 x 1.414 = about 170 VDC power supply voltage. 2 mosfets are connected to make an oscillator so each mosfet is ON 50% of the time and OFF 50% of the time. Operating frequency about 60KHz.
I experemented with current limiting resistors, 20w, 50w and 70 watt resistors all get hot enough to smoke. Resistors are not practical, too massive, too hot, too much wasted power. It appears to me to solution is to limit the current another way by not turning the mosfet on all the way.