Optimization methodology for control strategy of parallel hybrid electric vehicle based on chaos prediction

Irregular internal excitation (engine excitation and motor excitation) and external excitation (road excitation) can cause torsional vibration which even leads to the break of shaft of parallel hybrid electric vehicle (HEV) powertrain. Moreover, the current energy management control strategy ignores the significance of torsional stability of HEV powertrain when formulates the operating domain. The objective of this paper is to optimize the control strategy of parallel hybrid electric vehicle with multiple excitation sources to improve the torsional stability. To achieve the goal, the simplified two-mass nonlinear dynamic model of HEV powertrain is established. Then we apply the nonlinear dynamics to predict the torsional instability range of HEV powertrain. The theoretical analytical results are used to instruct to optimize the control strategy. Finally we set up the experimental platform and perform the experiment to verify the optimization of control strategy. The experimental results show that the HEV powertrain experience torsional instability under current control strategy. The critical speed when the operation mode of HEV switches from electric driving mode to hybrid driving mode was optimized to vc = 16km/h. The operating domain of engine was optimized to 1670 < n1 < 1850rpm under hybrid driving mode and driving and charging mode. The results reveals that optimization of control strategy can improve torsional stability of HEV powertrain effectively.