Detector circuit for detecting a phase signal of a polyphase alternator for a battery charge regulator in a motor vehicle, and utilization thereof

A detector circuit for detecting a phase signal of a polyphase alternator for a battery charge regulator in a motor vehicle, wherein said circuit includes differential signal amplitude discriminator means for discriminating between at least one pair of phase signals delivered by said alternator, said differential signal amplitude discriminator means including at least:

• two input terminals connected respectively to a first and to a second phase of said polyphase alternator, each receiving an alternator phase signal .phi..sub.1 or .phi..sub.2 ;
• and
• threshold comparator means for generating a signal representative of alternator operating conditions when the alternator phase amplitude differential exceeds a determined threshold value, said threshold comparator means including:
• a first threshold comparator means, including a first threshold value no greater than 1/20-th of the nominal charge voltage of the battery enabling a first signal representative of alternator operating conditions to be generated when the alternator is rotating at about 1500 rpm. in the absence of alternator excitation current;
• and
• a second threshold comparator means, including a second threshold value no greater than 1/2 of the nominal battery charge voltage enabling a second signal representative of alternator operating conditions to be generated corresponding to alternator phase voltage regulation conditions.