中文摘要：

从纯电动切换到发动机驱动，是并联混合动力汽车的状态切换模式之一。在切换过程中，为保持整车动力性能的平稳性和舒适性，必须对电机和发动机进行协调控制。以状态切换过程中总转矩不发生大的波动为控制目标，提出“发动机调速＋发动机／电机转矩优化分配”协调切换控制策略。建立并联混合动力汽车传动系统整车动力学模型，应用极大值原理，将二次型最优控制算法运用到控制策略中，并建立以车辆行驶平顺性为目标的泛函，设计了状态切换控制器。仿真结果表明，在动力切换过程中，该切换控制算法能有效控制混合动力系统在状态切换过程中的转矩波动，保证动力传递的平稳性。

英文摘要：

Switching from pure electric driving to engine driving is one of state-switch modes in PHEV. To maintain the dynamic stability and the riding comfort of vehicle during state-switch process, the coordinative control for motor and engine has to be achieved. Aiming at keeping the total torque unchanged during state- switch process, a state-switch coordinative control strategy is put forward, which can be expressed as torque optimization distribution between motor and engine after engine speed regulation. By building dynamic model for the PHEV powertrain system, and applying the quadratic optimal control algorithm to the state-switch control strategy on the basis of the maxmum principle, the state-switch controller is designed, in which the objective functional correlated with the driving smoothness is established. The simulation result show that the coordinative state-switch control algorithm can effectively control the torque ripple and ensure power transfer smoothly during state-switch processes in the hybrid power system. id electric vehicle （PHEV）