The Coordinate Control Strategy of Torque Recovery for the Parallel Hybrid Electric Vehicle

In this paper, a coordinated torque recovery strategy is presented and a robust control technique applied to motor torque control. It is well known that the torque recovery process influences vehicle power performance and driving comfort. In the torque recovery process, it is difficult to recover to the target torque as engine torque response is limited by emissions or the control algorithm in an Engine Control Unit (ECU), which results in poor vehicle power performance. To solve this problem and taking the different torque characteristics between the engine and the motor into consideration in the dynamic coupling process, a new coordination torque recovery control strategy based on the motor torque compensation for improving the vehicle performance is proposed. The engine torque is dynamically compensated by motor torque to improve power performance. In order to achieve better performance, a new control law, which employs the integral of the tracking error and state feedback, is described for the torque control of motors. The controller was designed by a linear matrix inequality (LMI)-based optimization to obtain an optimal gain. The simulation results illustrate the effectiveness and robustness of the controller. Finally, the torque recovery control strategy is compared to methods that do not use motor torque compensation. The comparative test results demonstrate that the proposed torque recovery control strategy improves the power of the vehicle effectively, reduces shift shock, and ensures comfort.