kenneth house
Since it is brushless and synchronous, i.e. frequency varies with speed, it would seem to be a permanent magnet rotor machine, with 3-phase wye winding plus neutral for the stator.
Not really. Here is a diagram of a CSD and generator:
http://www.pprune.org/tech-log/47743...ml#post7027969
Ignore the mechanical stuff and look at the schematic. Inside the generator, the field winding is supplied by an exciter generator. Essentially a little three phase generator on the same shaft, turned inside-out. Its output windings are on the rotor and rectified to supply the DC to the main generator field.
The main field is controlled (indirectly) by varying the exciter field (mounted on the generator case). The end effect is to have a controllable field with no brushes (high maintenance items).
Some generators do have a PMG (permanent magnet generator) in addition to all of the above. But this feeds control circuitry in the GCU enabling the system to 'black start' once the prime mover (turbine) is spinning. But since the 787 cannot start engines without some source of electrical power, the PMG function is less critical. I'm not sure if it has one.
