Patent ID: 7498776

Claim:
A control device for a vehicle AC generator comprising a stator coil, a field coil, a rectifying circuit connected to the stator coil, and a voltage control circuit that performs shutdown of and energization with a field current flowing through the field coil in accordance with an output voltage of the rectifying circuit and that controls the output voltage of the rectifying circuit to a substantially constant level, characterized in that the voltage control circuit has a first active switch having its one end connected to one end of the field coil and having its other end connected to a negative output terminal of the rectifying circuit, a second active switch having its one end connected to a positive output terminal of the rectifying circuit and having its other end connected to the other end of the field coil, a first passive switch connected between the negative output terminal of the rectifying circuit and a connecting point of the second active switch and the field coil, and a second passive switch connected between the positive output terminal of the rectifying circuit and a connecting point of the first active switch and the field coil, and the first and second active switches are on/off-controlled independently of each other.