基于行驶工况的纯电动汽车比能耗分析及传动比优化

Analysis of Specific Energy Consumption and Ratio Optimization of BEV Based on Running Schedule

通过分析长沙市市区行驶工况,根据汽车行驶方程,对采样点处汽车的微小能耗进行分析,并计及电动机制动能量的回收,推导出行驶工况下纯电动汽车的比能耗表达式。以环线行驶工况和市内行驶工况的比能耗和动力因数作为优化目标函数,根据电动机最高转速、峰值转矩和地面附着力对汽车性能的影响建立了传动系传动比的边界约束条件,同时为保证纯电动汽车在电池低荷电状态下仍具有一定的动力性和经济性,引入了电池低荷电状态时的传动比边界约束条件。引入加权系数,利用基于模拟退火的粒子群优化算法对所设计的纯电动汽车传动系的传动比进行了优化,在某组加权系数下,优化结果使得动力因数提高、比能耗降低。

Through the analysis of running schedule of Changsha,according to the automobile running equation,the minimal energy under the sampling points were analyzed,and the recycle of braking energy of motor was analyzed,the expression of specific energy consumption was derived.The objective function of optimization was established with the specific energy consumption under the loop and main-road running cycle and the dynamic factor,the boundary constraints of ratio optimization were established with the maximum speed and peak torque of the motor and traction.In order to assure the dynamic performance of the designed car under the lower state of charge of the battery,the boundary constraints were introduced in the optimization.A particle swarm optimization based on the simulated annealing was used in the optimization,the weighting coefficient was also introduced in the optimization.The optimization results increase the dynamic factor and reduce the specific energy of the designed car under a group of weighting coefficients.