Abstract: An alternator for a power generation system. The alternator includes a stator. The stator includes a main output winding, a poly-phase auxiliary winding and an exciter field winding that is powered by the poly-phase auxiliary winding. The alternator further includes a rotor that includes an exciter secondary winding and a rotary field winding that is powered by the exciter secondary winding. The rotary field winding voltage is determined by the exciter secondary winding voltage. In some power generation systems, the rotary field winding current of the rotor may be directly rectified from the exciter secondary winding current by uncontrolled rectifiers. The alternator further includes a regulator that measures a current to the exciter field winding. The regulator controls the current to a set point in order to regulate an output voltage produced by the main output winding of the stator.