You are not likely to get a reply IMHO, as the Question isn't exactly clear.
"Regulators" are normally used in DC circuits. FETs behave as a resistance (depending how they are driven) so I'm not clear how you can regulate a 220v ac output - what's the input . . . and importantly, what is the max/min load current?
That you haven't described the thing well makes me suspicious this is well thought-through.
Frankly, I sense a "smoking ruin" here - but Good Luck
with mains - be careful.