An alternator comprises a regulator configured to control the electric current to a field coil. The regulator includes a field driver circuit, the field driver circuit configured to deliver the electric current to the field coil at a switching frequency. The regulator further includes a controller configured to vary the switching frequency of the field driver circuit between a plurality of different switching frequencies. The alternator further comprises a sensor configured to detect a predetermined alternator condition, and the controller is configured to adjust the switching frequency of the field driver circuit in response to the sensed predetermined condition such as, for example, a rotor speed, a pulse width from the field driver circuit, an efficiency of the alternator, a temperature within the alternator, a temperature outside of the alternator, or magnetic noise of the alternator.