Torsional vibration control for power-split hybrid electric bus based on coordination of multiple excitation sources and clutch actuator

Mode transition can effectively improve the fuel economy of power-split hybrid electric bus (HEB). However, since the engine and motors are combined directly to the power-split device, the inconsistent dynamic characteristics of motors and engine, and delayed response of clutch actuator oil pressure can cause severe speed and torque fluctuations during mode transition. To address this issue, a torsional vibration control for power-split HEB based on coordination of multiple excitation sources and clutch actuator is proposed in this article. Firstly, a powertrain torsional dynamics model is established, and the mode transition process and control problem are analyzed. Then, a torsional vibration control strategy based on hierarchical optimization structure is designed. In the upper layer, the torque commands of the motors and clutch can be calculated by an improved wave superposition method and a fuzzy sliding mode control. In the lower layer, a triple-step nonlinear method is designed to perform the oil pressure tracking control of the clutch actuator. Finally, simulation results demonstrate that the proposed controller can effectively suppress the fluctuations of powertrain speed and torque, and exhibits obvious robustness against uncertain disturbances during mode transition. Moreover, hardware-in-the-loop test shows that the proposed controller is effective in the real-time environment.