Abstract: A hybrid electric vehicle includes an engine, a first motor directly connected to the engine, an engine clutch, a second motor selectively connected to the first motor through the engine clutch, a transmission directly connected to the second motor, a transmission controller configured to determine whether the transmission needs to be shifted, and a hybrid controller configured to compare a target torque reduction with intervention limits of the first and second motors when the engine clutch is in a locked-up state, to set torque reduction amounts of the engine, the first motor, and the second motor, respectively, and to output a torque command for controlling the torques of the engine, the first motor, and the second motor, respectively.

Abstract: A shift control method of a hybrid electric vehicle includes: determining a speed control torque based on a result of comparing a speed of an input end of a transmission with a target speed of the input end of the transmission according to a shift signal; distributing the speed control torque to a second motor connected directly to the input end of the transmission; and distributing a residual speed control torque to a first motor connected selectively to the second motor through an engine clutch based on whether the engine clutch is locked up when the speed control torque is greater than a charging limit torque of the second motor.

Abstract: Disclosed are a backlash vibration reduction apparatus and method capable of sufficiently performing gear alignment even when torque is increased while a vehicle is driven within a low torque range, thereby minimizing rough vibration due to backlash. The backlash vibration reduction apparatus includes a correction determination unit configured to determine whether it is necessary to correct a torque gradient to be applied for an increase to target torque in the state in which the current torque of a vehicle is retained within a predetermined low torque range and a torque gradient correction unit configured to determine a corrected torque gradient in which a torque increase rate per hour is reduced and a torque increase time period is extended by multiplying a correction factor by a first torque gradient as a torque gradient that increases the current torque upon determining that it is necessary to correct the torque gradient.

Abstract: Disclosed are a hybrid electric vehicle and an engine control method therefor that are capable of reducing entry of an engine into a full-load drive mode. The method includes determining whether the extent of depression of an accelerator pedal (APS) may be equal to or greater than a reference value set as a condition for entry of an engine into a full-load drive mode, determining a part-load torque corresponding to the maximum torque in a part-load drive mode of the engine and a motor torque corresponding to the maximum torque of a motor when the extent of depression of the accelerator pedal may be equal to or greater than the reference value, comparing the sum of the part-load torque and the motor torque with a driver demand torque, and controlling the engine in the full-load drive mode or the part-load drive mode depending on a result of the comparing.