Method and apparatus for detecting alternator rectifier diode short fault

A method comprising:

• sampling a field winding signal of an alternator, during operation of the alternator;
• band pass filtering the field winding signal that is sampled;
• and
• detecting a short fault of an electronic component of a rectifier coupled to an output of the alternator in the event that an amplitude of the band pass filtered field winding signal exceeds a fault threshold.

An apparatus comprising:

• a hysteresis frequency counter that is operatively connected to sample a field winding signal of an alternator and to output a value indicative of a fault ripple frequency, based on a ripple of the field winding signal exceeding a fault threshold;
• a countdown timer;
• and
• a frequency comparator that is operatively connected to compare the fault ripple frequency to an alternator armature frequency, and to actuate the countdown timer in the event that the fault ripple frequency closely matches the armature frequency;
• wherein the countdown timer is operatively connected to be actuated by the frequency comparator, and is configured to signal a short fault of an electronic component of a rectifier coupled to an output of the alternator in the event that the fault ripple frequency closely matches the armature frequency for a countdown time.