Research On Matching And Optimization Of Powertrain System Of Pure Electric Commercial Vehicles Based On Working Condition Requirement

Electric vehicles,with advantages such as zero emissions,low noise,and simple structure,are highly valued by car manufacturers,gradually becoming the main direction of new energy vehicle development.However,current pure electric vehicles have issues such as low battery energy density,long charging time,short driving range,and optimization of the energy utilization rate of the driving motor,which restrict the improvement of overall vehicle performance.In order to maximize the power and economy of the vehicle,it is particularly important to rationally match and optimize the parameters of the vehicle’s power transmission system.This paper uses a certain brand’s 18 t pure electric truck as the research object,and completes the matching design of the power transmission system.Numerical characteristic analysis is performed on the China Heavy-Duty Commercial Vehicle Test Cycle(CHTC)working condition.The energy distribution and high-frequency working range of the motor are determined by theoretical calculations.The main parameters of the vehicle’s motor,battery,and transmission system are analyzed for matching.A permanent magnet synchronous motor is selected as the power source for the whole vehicle,and a ternary lithium battery is used as the energy source for the whole vehicle.The series and parallel connection of the battery pack is calculated based on the voltage and capacity of the single battery.The transmission structure of the three-speed AMT gearbox and the main reducer is determined,and the initial speed ratio of each gear is divided according to the shifting strategy,and the economic matching is performed using numerical statistical methods.The whole vehicle modeling simulation is completed in the Cruise environment.A complete vehicle power transmission system model is built using Cruise software,and a power performance simulation task is designed.An economic calculation is conducted,and the matching parameters are verified to meet the design requirements through simulation calculation.The multi-objective optimization workflow and algorithm research of the power transmission system have been completed.With power and economy as the constraint conditions,the main reduction ratio and the speed ratio of each gear as the optimization variables,an optimization model is established with the electric consumption of high-speed driving per hundred kilometers and CHTC-HT cycle electric consumption as the objective functions,and the Non-dominated Sorting Genetic Algorithm I(NSGA-II)is selected as the optimization algorithm.A set of transmission system parameters that meet the design requirements and have a higher energy utilization rate are optimized out,realizing the reduction of electric consumption per hundred kilometers and the increase of driving range.The optimization method research of the power transmission system has been completed.Using Isight and Cruise software,the integrated optimization of the power transmission system is conducted with overall vehicle performance as the optimization goal,and multiobjective optimization is carried out.The results show that the power performance well and significantly improved economic performancing.