Method for regulating the excitation current in a motor vehicle alternator by digital processing, and a regulating device for carrying out the method

摘要

The excitation current in the rotor winding of a motor vehicle alternator is regulated by this method. The alternator produces a rectified output voltage to be regulated, this output voltage being a periodic voltage having a period T consisting of a first phase T.sub.1 in which the battery voltage is applied to the rotor winding, and a second phase T.sub.2 in which the battery voltage is not applied to the rotor winding. The method includes: measuring the rectified voltage by sampling during each period T; comparing the measured value with a calculated reference value; and deducing from this comparison three numerical values. The first of these corresponds to the difference between the measured value of the rectified voltage and the reference value. The second of these numerical values is a closed loop excitation value calculated in each period T by adding the corresponding value measured in the preceding period to the first numerical value, to which a first correcting factor is applied. The third numerical value is an open loop excitation value calculated, in each period T, by adding together the closed loop excitation value already calculated in the same period and the first numerical value, to which a second correcting factor is applied. The duration of the first phase of the rectified voltage is determined by the value of the open loop excitation.