The power-split hybrid electric vehicle (PS-HEV) has multiple working modes to maintain high operation efficiency according to different conditions. The main modes involved in the vehicle driving process are pure electric mode and the hybrid driving mode. Because the electromechanical coupling problem is involved in the above two working modes, the transmission system exhibits strong non-linear characteristics. If the operation range of the engine and motor are unreasonable, the rotor system will vibrate and become instability. In this paper, the non-linear dynamic equations of the electromechanical coupling of the transmission system are established for electric driving mode and hybrid driving mode. The closed-homoclinic phase trajectory equation at the center point of the disturbance-free Hamilton system is determined. The chaotic thresholds for the pure electric and hybrid driving modes are derived through the Melnikov’s method to obtain the optimal working domain of the engine and motor. Finally, numerical simulation analysis is conducted to verify the feasibility of the work domain optimization scheme. Simulation results show that the proposed engine and motor working area optimization scheme can effectively avoid the homoclinic bifurcation in the PS-HEV during the driving process and prevent the vehicle from entering the chaotic state.

动力分配式混合动力电动汽车（PS-HEV）具有多种工作模式，可根据不同条件保持较高的运行效率。车辆驾驶过程中涉及的主要模式是纯电动模式和混合动力驾驶模式。由于上述两种工作模式都涉及机电耦合问题，因此传动系统具有很强的非线性特性。如果发动机和电动机的工作范围不合理，转子系统将振动并变得不稳定。针对电动行驶模式和混合动力行驶模式，建立了传动系统机电耦合的非线性动力学方程。确定了无扰动汉密尔顿系统中心点的闭相相位轨迹方程。通过梅尔尼科夫方法得出纯电动和混合动力行驶模式的混沌阈值，以获得发动机和电动机的最佳工作范围。最后，进行了数值仿真分析，验证了工作域优化方案的可行性。仿真结果表明，提出的发动机和电动机工作区优化方案可以有效避免行驶过程中PS-HEV的同斜分叉，并防止车辆进入混沌状态。