Powering 100w 32v LEDs
The circuit you have drawn will not do what you want. If I were going about things this way, this is what I would do:







simulate this circuit &ndash; Schematic created using CircuitLab

How you implement the current sink is up to you. You could have a simple current sense resistor + feedback driving a linear pass transistor (if you want to dissipate lots of heat). If this is passing 3A (which is roughly what those LEDs are pulling) and has to drop 10V of extra voltage, that's 30W of heat you need to dump off into a heatsink. Not impossible, but requires thought. You can see the basic design of a linear current sink here.

You could also implement a current-controlled buck converter for the LEDs - although rating this for the full rectified mains voltage will require consideration. The link in @Damien's comment above is a good place to start looking, specifically using something like the Fairchild FL7701. This would be much more efficient, but requires a more sophisticated design.