The generator is a three-phase synchronous electric machine with electromagnetic excitation. The voltage is regulated by the built-in voltage regulator.
When the generator is running, the electric current flowing through the field winding creates a magnetic flux around the rotor poles. When the rotor rotates, then the south and then the north pole of the rotor passes under each stator tooth and the working magnetic flux passing through the stator teeth changes in magnitude and voltage. This variable magnetic flux creates an electromotive force in the stator winding.
At a high frequency of rotation of the generator rotor, when the generator voltage becomes greater than 13.6–14.6 V, the voltage regulator located in the brush holder is locked and the current does not pass through the field winding. The generator voltage drops, the regulator opens and again passes current through the excitation winding. The higher the frequency of rotation of the generator rotor, the longer the time of the closed state of the regulator, therefore, the more the voltage at the generator output decreases. The process of locking and unlocking the regulator occurs at a high frequency, so the voltage fluctuations at the generator output are imperceptible and can practically be considered constant, maintained at a level of 13.6–14.6 V.