Philippe said:
It was just an idea.
I was asking myself if a signal elaborated by the difference between speed
and fixed frequency can eventualy drive the AVR to maintain the voltage on
the stator.
Of course i'm sure that the technology of the rotor may be very complex.
We may found application for hydroelectric plant perhaps.
Its more appropriate for a prime mover whose speed must be regulated for
some other application and the generator is a secondary load. Automotive
or aircraft engines are an example, where the RPM is dictated by
propulsion requirements.
Rather than some complex rotor drive circuitry, the approach is to let
the generator follow the prime mover's speed and generate variable
frequeencies. The output is then rectified and used to produce fixed
frequency AC via various solid state switching topologies.