Analysis and Optimization of a Hybrid Electric Bus's Starting Condition

The engine starting process of hybrid electric buses equipped with clutches usually generates overlarge torques on the main axle, which is undesirable. This paper targets at eliminating the torque strike on the main axle during this process. The powertrain mechanics is modeled. A novel multi-objective downhill simplex optimization method is proposed to optimize the rigidity, damping and other axle parameters. Simulation results show that with optimized parameters, the maximum torque upon the axle is reduced by 64.7%, and the first order natural frequency is increased by up to 1.02%. A pareto front is also presented to provide an overview at the fundamental performance.