Let me organize my thougts:
An AC voltage rectifier is pricier than a 100V DC rectifier (ex. TL783 costs some 3-4$).
So, it would be cheaper just to rectify from AC and then setup a voltage divider using 50W rated resistors with aluminium heatsink, from which I would get in different grid voltages:
My AC is very stable at 222V, but who knows...
AC 210V
Rectified DC 294V
50W RESISTORS DC OUT
R1 100,00 OHM 96,08 V
R2 100,00 OHM 96,08 V
R3 100,00 OHM 96,08 V
R4 6,00 OHM 5,76 V
AC 220V
Rectified DC 308V
50W RESISTORS DC OUT
R1 100,00 OHM 100,65 V
R2 100,00 OHM 100,65 V
R3 100,00 OHM 100,65 V
R4 6,00 OHM 6,04 V
AC 240V
Rectified DC 336V
50W RESISTORS DC OUT
R1 100,00 OHM 109,80 V
R2 100,00 OHM 109,80 V
R3 100,00 OHM 109,80 V
R4 6,00 OHM 6,59 V
On each DC aprox. 100V I would connect a TL738 with proper heatsink, aiming to get around 90-95V, a value that would be established after measuring the voltage drop of the led string.
The 6V (or 2V or whatever) would be used to get optocouplers to control MOSFETs (something like IRF9540s), and enable an Arduino to control all the strings via optocouplers.
I know that probably power dissipation is in order, the whole setup would be in a box with a pc fan to prevent overheating.
What can I add to prevent AC voltage spikes to get to the DC side, I you know what I mean? 400V capacitors on the DC side?
Any thougts on this? Am I missing anything? Thanks.