Patent ID: 6081103
Filing Date: 2000-06-27
Classification: H02J,H02P,Y02T

Abstract:
In a vehicle having an alternator and a battery connected to the alternator, a method of regulating the excitation current in a rotor winding of the alternator, the alternator comprising: a stator; a rotor including said rotor winding, the stator comprising stator windings; and a rectifier bridge connected to the said stator windings for delivering a rectified output voltage to be regulated by the said method, the said rectified voltage having a waveform comprising a low frequency, variable amplitude, component produced by the said excitation current, whereby the said rectified voltage is a periodic voltage of period T, with each said period T consisting of a first phase and a second phase, the said first phase being a phase in which the voltage of the battery is applied to the stator winding, and the second phase being a phase in which application of the battery voltage to the stator winding is absent, wherein the said method includes the steps of:measuring the rectified voltage by sampling;performing a comparison between the measured value of the rectified voltage and a calculated reference value; anddeducing from the said comparison first, second and third numerical values, wherein the said first numerical value corresponds to the difference between the measured value of the rectified voltage and the reference value, the said second numerical value being a closed loop excitation calculated, for each period T, by adding to the value of the closed loop excitation in the preceding period the said first numerical value, to which a first correcting factor is applied, and the said third numerical value being an open loop excitation which is calculated, in each period T, by adding to the value of the closed loop excitation previously calculated during the same period T the first numerical value, to which a second correcting factor is applied, the said third numerical value determining the time T.sub.1 during which the battery voltage is applied to the rotor winding of the alternator.