One of the major issues for Parallel Hybrid Electric Vehicle (Parallel HEV) powertrain is the torsional vibration in the process of start condition, which is unavoidable. This article targets at reducing the damage caused by the torsional vibration with the method of Multi-Objective Optimization (MOO). The dynamic model of the parallel HEV powertrain is established by lumped mass method. Five design variables are selected from 19 parameters by the process of Design of Experiment (DOE), and are optimized by multi-objective downhill simplex optimization algorithm. Pareto Frontier is used to describe the relationship between the two objective functions, and one of the optimization data serves as the basics data for the powertrain modification. Finally, the results of optimization before and after optimization are compared by the test bench. Experimental results under the start condition show that the maximum torque of the optimized powertrain is decreased within the safe range, and the problem of shaft breaking on the originally powertrain is solved.

并联混合动力电动汽车（Parallel HEV）动力总成的主要问题之一是启动条件过程中的扭转振动，这是不可避免的。本文旨在通过多目标优化（MOO）的方法减少扭转振动造成的损害。采用集中质量法建立了并联式混合动力汽车动力总成的动力学模型。通过实验设计（DOE）过程从19个参数中选择了五个设计变量，并通过多目标下坡单纯形优化算法对其进行了优化。Pareto Frontier用于描述两个目标函数之间的关系，并且优化数据之一用作动力总成修改的基础数据。最后，测试台将优化前后的优化结果进行比较。