48 volt power supply Answered

Hello everyone. i am interested in building a power supply from 0-48 volts and able to push a good amount of amps. any one have a ruff idea on how to beable to adjust the voltage and not limit my current to 2 amps i would like to puch say 15-20 amps. i can build the rectifier i have a 600v i think 30 amp bridge rectifier. just not sure on how to do the adjusting without useing a regulator chip that only pushes a few amps. any help would be greatly appreciated.