Only the construction and performance has changed. Various engine management systems have taken over the output control but the mechanism of control is still varying the field current.
My Bosch rep told me of the newest alternators that should be coming out in the 42 volt systems. They use the cars flywheel as the rotating field and can be rereverse wound (or controlled) to make them into starters. The point being to allow cars engines to stop at idle and then be smoothly brought to speed with magnetism.
Bosch Master, ASE Master, L1
33 years MB technician