A Robust Design Method for Optimal Engine Operating Zone Design of Plug-in Hybrid Electric Bus

The optimal engine operating zone of energy management plays an important role in the fuel economy improvement of Plug-in hybrid electric buses. However, the existing investigations usually design the engine operating zone by experience. This paper proposes a robust design method for the robust and optimal design of the engine operating zone. Firstly, a nonlinear model predictive control (NMPC)-based energy management together with a single-point preview SOC (state of charge) plan method is designed. Then, a Taguchi robust design model is designed to find the optimal engine operating zone by taking the energy management as underlying solving module. Particularly, the noises of driving cycles and stochastic vehicle mass are considered to improve the robust performance of the engine operating zone. Finally, The Monte Carlo Simulation is deployed to verify the robustness and optimal performances of the designed engine operating zone. Simulation results demonstrate that the proposed method is beneficial to the fuel economy improvement, where the fuel economy can be averagely improved by 9.10% compared with the experienced designed engine operating zone, and can be averagely improved by 16.34% compared with the rule-based energy management strategy.