Mode transition control using disturbance compensation for a parallel hybrid electric vehicle

This paper proposes a new approach for the mode transition control in a parallel hybrid electric vehicle (HEV) with an engine clutch. During mode transition, a noticeable jerk or torque fluctuation in the hybrid powertrain, which may result in the vibration of the drivetrain and an unpleasant driving sensation, occurs frequently because of discontinuity of the dynamics and the characteristics of the powertrain system. Therefore, ensuring smooth vehicle operation during the mode transitions is an important objective of the HEV control. This paper presents a four-phase control strategy during transition from the electric vehicle mode to the hybrid mode by using disturbance observers. The disturbance observer estimates and compensates for disturbances to improve control accuracy, tracking performance, and drivability. The vehicle model is developed to represent the characteristics of the transient response of the target system and is used to simulate and verify the proposed control algorithms. The simulation results show the validity of the proposed control algorithms.