并联式混合动力汽车模式切换控制策略研究

并联式混合动力汽车模式切换时离合器会介入传动系统，容易引起较明显的冲击感，是影响整车驾驶舒适性的主要因素。为此，提出了基于离合器双模糊和电机转矩协调的模式切换控制策略。首先建立混合动力汽车模式切换过程的动力学模型，以减小离合器滑磨功为目标，对模式切换时的离合器接合过程进行划分；其次，结合混合动力汽车模式切换的基本要求和驾驶意图，制定离合器双模糊控制策略，分别对滑摩阶段的接合时长和转矩同步阶段的压力变化率进行控制；然后以离合器滑磨功和整车冲击度为优化目标，采用二次型最优控制算法对滑摩阶段的接合压力进行优化，从而获取模式切换过程中离合器的最优接合压力轨迹；在此基础上，通过实时计算离合器传递转矩，根据电机转矩响应快的特点，制定电机转矩协调控制策略；最后，基于某混合动力试验样车，在底盘测功机上分别进行缓加速、中等加速和急加速下的模式切换试验，对所提出的控制策略进行验证。试验结果表明：该策略能较好地反映驾驶人驾驶意图，保证离合器的使用寿命，所产生的整车冲击度均处于合理范围之内，改善了整车模式切换过程中的驾驶舒适性。

Research on Mode Switching Control Strategy of Parallel Hybrid Electric Vehicle

The main factor affecting driving comfort in a parallel hybrid electric vehicle (HEV) is the distinct sense of impact caused when the clutch intervenes in the transmission system while switching modes in the vehicle. Thus, a mode-switching control strategy based on the dual-fuzzy clutch and motor torque coordination control is proposed in this paper. A dynamic model of the HEV mode switching process was established, and the clutch engagement process during mode switching was divided to reduce the clutch slip work. Combined with the basic requirements of HEV mode switching and driving intention, the clutch double fuzzy control strategy was developed to control the engagement time length and pressure change rate of the clutch slip and torque synchronization phase, respectively. With the vehicle jerk and clutch slip work as the optimization goal, the quadratic optimal control algorithm was then used to optimize the engagement pressure in the slip phase, to obtain the optimal engagement pressure trajectory of the clutch during the mode switching process. Considering this, through the real-time calculation of clutch transfer torque, the motor torque coordination control strategy was established quickly according to the characteristics of the motor torque response. Finally, the proposed control strategy was verified by the mode switching test for slow, medium, and rapid acceleration on the chassis dynamometer, based on a hybrid test prototype vehicle. The strategy has the potential to better reflect the driver's driving intention and ensure the service life of the clutch. The maximum vehicle dynamic impact is within a reasonable range, which improves the driving comfort of the vehicle mode switching process.