PMG is Permanent magnet generator. The alternator generaly
uses a self excited generator and converts its voltage to DC
and then applies to alternator armature windings.
this kind of alternators are named as brushless modern
alternators.

The answer above is partially correct. All AC alternators
presently manufactured are brush less type with built in
AVRs ( Automatic Voltage regultors ) Normally AVR get feed
back from load for its regulation. If the loads connected
have excessive harmonic content, feed back to AVR get
distorted and hence regulation gets affected. To avoid this
a PMG is mounted on the alternator itself which feed DC to
armature winding without reference to the load

both the answer is right 


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