Patent ID: 7098628

Claim:
A generation control system for a vehicle having a battery comprising: an ac generator driven by an internal combustion engine; field current control means for controlling the duty ratio of field current of the ac generator; field current detecting means for detecting the field current; load current detecting means for detecting current supplied to an electric load of a vehicle; rotation speed detecting means for detecting rotation speed of the ac generator; driving-torque-increase calculating means for calculating a predicted increase in driving torque of the ac generator from increase in the current supplied to an electric load; wherein said driving-torque-increase calculating means comprises: first output current calculating means for calculating present output current of the ac generator as first output current from the generator's rotation speed and the field current; second output current calculating means for calculating predicted output current of the ac generator as second output current from the first output current and the increase in the current supplied to the electric load; a predicted increase in driving torque of the ac generator is calculated from a difference between a driving torque that corresponds to the first output current and driving torque that corresponds to the second output current, said driving-torque-increase calculating means includes a map that stores correlative data of the output current of the ac generator and the rotation speed of the ac generator; maximum field current is obtained from the map based on the field current and the duty ratio of the field current; output current of the ac generator that corresponds to the maximum field current is obtained from the map as maximum output current; and a different between driving torque that corresponds to the first output current and driving torque that corresponds to the maximum output current is calculated as a predicted increase in the driving torque if the second output current is larger than the maximum output current.