Analysis and control of engine starting process based on a novel single-motor power-reflux hybrid electric vehicle

• A novel single-motor power-reflux hybrid transmission system is proposed. • The characteristics are analyzed based on dynamic model of hybrid powertrain . • The work law of driving and speed regulating mode switches is formulated. • Comprehensive multilevel coordination control strategy is proposed at engine start. • Simulation results show engine starting jerk effectively is reduced by 65.88%. In this study, a novel single-motor hybrid electric vehicle (HEV) equipped with a power-reflux coupling transmission system is proposed for improving the fuel economy of HEVs. The structural characteristics and operating principles of the proposed HEV were analyzed, and a detailed driveline dynamic model was established. Then, a rule-based energy management strategy regulated by the optimal comprehensive energy economy was adopted to divide its working mode regions. As a result, the engine starting process in vehicle motion may involve not only a driving mode switch but also a speed regulation mode conversion, resulting in noticeable jerks and an unpleasant driving sensation. To address this problem, this study presents a multilevel torque coordination method that synergizes the transient intervention of torques from two power sources and clutches and changes the transmission ratio. Compared with the simulation results of the dynamic performance of a vehicle under conventional control strategy, the results of the proposed control strategy demonstrate a better control effect, which can ensure the smoothness of power transmission during engine startup to effectively minimize the impact on the system and improve the ride comfort.

•提出了一种新型单电机功率回流混合动力传动系统。 •基于混合动力系统的动力学模型分析了其特性。 •制定了驱动和调速模式切换的工作规律。 •提出了发动机启动时的综合多级协调控制策略。 •仿真结果表明发动机启动冲击有效降低了65.88%。 在本研究中，为提高混合动力汽车的燃油经济性，提出了一种配备功率回流耦合传动系统的新型单电机混合动力汽车（HEV）。分析了所提出的混合动力汽车的结构特征和工作原理，并建立了详细的传动系动力学模型。然后，采用由最优综合能源经济性调节的基于规则的能量管理策略来划分其工作模式区域。结果，车辆运动中的发动机启动过程可能不仅涉及驱动模式切换，还涉及调速模式转换，导致明显的冲击和不愉快的驾驶感受。为解决这一问题，本研究提出了一种多级扭矩协调方法，该方法协同两个动力源和离合器的扭矩瞬态干预并改变传动比。与常规控制策略下车辆动态性能的仿真结果相比，所提出的控制策略的结果显示出更好的控制效果，能够确保发动机启动期间动力传输的平稳性，有效减小对系统的影响并提高乘坐舒适性。