A VOLTAGE CONTROL APPARATUS FOR ELECTRIC GENERATORS FOR VEHICLES

摘要

A voltage control apparatus for an electric generator (2-4) for vehicles includes an armature winding (3), an exciting coil (4), a rectifier (2) for rectifying an a.c. output from the armature winding (3), and a voltage regulator(5). The voltage regulator (5) comprises a differential amplifier circuit (26) producing a detected voltage corresponding to a difference between a battery charging voltage and a reference voltage, a comparator circuit (30) comparing the detected voltage with a triangular waveform voltage generated at constant periods and producing a pulsed output voltage, a first driver circuit (51) effecting duty-factor-control of an exciting current flowing through the exciting coil (4) in response to the pulsed output voltage, and an initial excitation circuit (32) for causing a predetermined small initial exciting current to flow through the exciting coil (4) intermittently during a time interval after the start of the electric generator (2-4).