摘要:
A mean vehicle speed Va and a mean variation .DELTA.Va are factors reflecting a current driving condition and an expected driving condition of a vehicle, which relate to a charge-discharge amount of a battery. A target state SOC* of the battery is calculated from the mean vehicle speed Va and the mean variation .DELTA.Va. The charge-discharge amount of the battery increases with an increase in mean vehicle speed Va and mean variation .DELTA.Va. The lower charging state of the battery results in the higher charge-discharge efficiency. The structure of the present invention sets the target state SOC* of the battery and controls the actual state of the battery to the target state SOC*, thereby enhancing the charge-discharge efficiency of the battery and ensuring a sufficient supply of electric power required for driving the vehicle.