Patent ID: 7684906

Claim:
A method of controlling a hybrid vehicle that is driven by at least one of an engine and a motor generator, the motor generator exchanging power with a battery, the method comprising: determining whether the vehicle is accelerating, decelerating, or traveling at a substantially constant speed; selecting a range of a state of charge of the battery based on whether the vehicle is accelerating, decelerating, or traveling at the substantially constant speed; and controlling at least one of: torque and number of rotations of the engine and the motor generator, such that the power being exchanged between the battery and the motor generator is such that the state of charge is within the selected range; wherein determining whether the vehicle is accelerating, decelerating, or traveling at the substantially constant speed comprises determining that the vehicle is decelerating when the sum of a first power, which is determined by creep torque, and a second power, which is determined according to a vehicle speed and an amount of depression of an accelerator pedal, is negative; wherein selecting the range of the state of charge of the battery comprises setting a lower limit of the range to a first or second value and setting an upper limit of the range to a third or fourth value, wherein the first value<the second value<the third value<the fourth value; wherein when the vehicle is decelerating, the upper limit is set to the fourth value; wherein when the vehicle is decelerating, the lower limit is set to the second value; wherein when the vehicle is accelerating or traveling at the substantially constant speed and an amount of depression of the accelerator pedal is equal to or larger than a reference value, the lower limit is set to the first value; wherein when the vehicle is accelerating or traveling at the substantially constant speed and an amount of depression of the accelerator pedal is equal to or larger than a reference value, the upper limit is set to the third value; wherein when the vehicle is accelerating or traveling at the substantially constant speed and an amount of depression of the accelerator pedal is less than or equal to a reference value, the lower limit is set to the second value; and wherein when the vehicle is accelerating or traveling at the substantially constant speed and an amount of depression of the accelerator pedal is less than or equal to a reference value, the upper limit is set to the third value.