0-24V 0-47A DC-DC Converter
For this much current you should use a switching topology, such as a buck converter.
some PWM controller IC such as uc3842, and a method to control the IC's feedback path. Some OPAMP signal conditioning for current and voltage sensing and probably a microcontroller for more flexibility in control algorithms. Most of the control circuitry and conditioning is the same as a linear regulator which you mentioned, the difference is in the PWM Controller and the output switch and output filtering.
you can find a good article to improve your knowledge on linear power supply design here:
Fully Programmable Modular Bench Power Supply