System-Level Energy Management Optimization of Power-Split Hybrid Electric Vehicle Based on Nested Design

The power-split hybrid electric vehicle (PS-HEV) is a complex and high-dimensional system that only through overall system-level optimization, considering the synergies and complementation between different components and subsystems, can achieve the best overall performance and benefits, which has been a technology challenge in the study. This article presents a system-level optimization method using nested design for engines and motors to solve the problem of the coupling between the parameters of the physical system and those of the control algorithm. Cohen's f effect is employed to conduct sensitivity analysis and determine the influence of the selected design parameters on the optimization objective. The Kriging model and NSGA II algorithm are proposed to optimize the motor, whereas the fire hawk algorithm is selected to optimize the fuel consumption objective. To evaluate the performance of the optimal torque distribution, a comparison is made with the original PS-HEV system, and the feasibility of the proposed scheme is verified through the hardware-in-the-loop test. The results demonstrate the efficacy of the proposed system-level optimization method in achieving superior performance of the PS-HEV system.