Development Of Vehicle Powertrain Performance Simulation And Optimization Platform Based On Common Law Analysis

In the concept development stage of vehicle powertrain,there are extensive demands for powertrain performance simulation and optimization,which can improve the efficiency of powertrain performance development.At present,in the aspect of performance simulation,the establishment of simulation model consumes a lot of time,and the modeling process is cumbersome,with many parameters,and the setting of boundary conditions lacks basis.In terms of performance optimization,it takes a lot of time,and there are many parameters in the optimization design process.There is a complex relationship between the control parameters and performance parameters of the gasoline engine.At the same time,under the background of the era of“Emission Peak”and“Carbon Neutrality”and the era of environmental protection,the development of gasoline engines with high efficiency and better emission performance has broad prospects.This paper will develop a software platform for powertrain performance simulation and optimization,and the performance simulation module will summarize the common laws of gasoline engine power,economy and emission performance based on the performance benchmarking test results of multiple gasoline engines,and establish gasoline engine simulation model;in the performance optimization module,the multi-objective and multi-parameter optimization of gasoline engine performance is completed based on the NSGA-Ⅱoptimization algorithm.It provides the correct optimization direction for the numerical development of gasoline engine performance.(1)Based on the results of gasoline engine performance benchmarking experiments,this paper analyzes the influence of gasoline engine operating parameters and control parameters on gasoline engine power,economy and emission performance,and summarizes the common laws of its key parameters.Among them,the power of gasoline engine has a good linear relationship with intake density and charge coefficient;the mechanical efficiency of gasoline engine is affected by load and speed.(2)The economy of gasoline engine is mainly affected by the pump,the combustion process in the cylinder and the conversion process of heat and power.The research shows that the combustion efficiency has a significant linear relationship with the Lambda;in the Weber combustion model,the combustion quality parameter is generally about 2.The Burn Duration 10-90%and the 50%Burned Crank Angle are affected by the engine speed,residual gas coefficient in the cylinder,Lambda and ignition advance angle,and there is a clear functional relationship among them.(3)In the emission performance of gasoline engines,the emission of NO_x is significantly affected by Lambda and the maximum combustion temperature;the emission of HC is more sensitive to Lambda,and the combustion speed and combustion temperature will also affect the emission of HC;the emission of CO is only affected by Lambda.(4)Based on the general laws summarized above,this paper establishes a simulation model of gasoline engine performance.Secondly,the multi-objective and multi-parameter optimization of gasoline engine performance is carried out based on the NSGA-II algorithm.The BSFC and NOx emissions are selected as the optimization target values,and the ignition advance angle,the intake and exhaust value timing,Lambda and fuel injection timing are selected as the optimization parameters.Three different load conditions of low,part and full load at 2000 r/min are selected for optimization.After optimization,the BSFC is reduced by 5%and 7%respectively under the part and low load conditions.Under full,part and low load conditions,NOx emissions are reduced by 10%,34%and 85%,respectively.The research in this paper will help to speed up and simplify the development process of gasoline engine performance,and has important reference value for the optimization of gasoline engine economy and emission performance.