How to choose FPGA for converter control?

You must design these parts by yourself and integrate together. I would strongly recommend to stay away from FPGA/CPLD without proper knowledge. It will bring a lot of frustration if you start doing something with no idea how to finish it. True story: guys took MAX V CPLD to switch transistors at 100 MHz, they wrote a lots of code and wondered why it didn't work properly. Since they had no FPGA training they ignored timing problems, unconstrained design was able to run up to 24 MHz. The story ended with doubled budget and not meeting deadlines. These guys now believe, that FPGAs are a devil's toys and took a fast microcontroller for 2nd generation product.