An alternator in a car is different. It has to have a battery to provide
its field with DC. An AC generator has permanet magnets in the rotor and
the current is induced in the field where the RPM of the rotor is
responsible for how much voltage is produced.



As I said before, this is not a permanent magnet generator, it has a
wound rotor and is more similar to a car alternator than you think.
Frequency is determined by the RPM, voltage is not, at least it is not
adjusted or regulated by varying the RPM.

At any rate, after doing some more research I think I have a pretty good
idea of how it works. It's the same principal as spinning an induction
motor to generate power except the armature with copper windings and a
rectifier are much more efficient for generating than the aluminum bars
in a motor armature. The service manual doesn't have an internal
schematic so I'm not sure how the capacitor connects but I can guess.
It's a clever concept at any rate, I'm not sure why they don't all work
this way but I've seen similar generators which had slip rings and a
circuit board to regulate the output much like a car alternator uses.