Research on operating domain optimization of power split hybrid electric vehicle based on global bifurcation and chaos threshold

Abstract

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.