Control system for A.C. generator

Claim 1

A control system for an a.c. generator having a field winding and armature windings comprising: rectifying means including rectifying transistors individually operatively connected between respective output terminals of the armature windings of the a.c. generator and one of a high and a low voltage terminal of a battery, and a drive controlling circuit for controlling operation of the rectifying transistors; an exciting current controlling transistor providing on/off control of an exciting current to the field winding of the a.c. generator; voltage controlling means for controlling a duty ratio of the exciting current controlling transistor so as to decrease a difference between a voltage across the battery and a prescribed reference voltage; state determining means for determining, according to a parameter associated with a rotation sped of the generator, whether the rotation speed thereof is in a high load torque rotation range in which a load torque of the generator becomes maximum; and exciting current limiting means for limiting the exciting current to less than a prescribed value responsive to the speed of the generator is determined to be in the high load torque rotation range, wherein the rectifying current controlling transistor includes a MOS transistor made, as a base material, of a monocrystalline SiC which is a compound of Si and C.