| As a main way of transportation,the electric logistics vehicles are not only conducive to the logistics industry,but also releases the potential of the domestic logistics trade market,protects the environment and saves energy.Based on the Scientific and Technological Developing Scheme of Ji Lin Province(project number:20180201060GX),aiming at the power transmission system,a pure electric logistics vehicle with a full load quality of 3.5 tons to 4.5 tons is established as the research object.The working condition method and genetic algorithm are proposed for parameter matching and transmission ratio optimization of the power transmission system to improve the driving range of the pure electric logistics vehicle.The main contents are as follows:(1)After the investigation and summary of the topic worldwide,the current development of electric logistics vehicles is pointed out based on products.The research of key technologies of power transmission system is reviewed,and the research content of this article is summarized.(2)The factors affecting the driving range of electric logistics vehicles is analyzed.A simulation model of the driving range for a pure electric logistics vehicle under the constant speed condition and the CHTC-LT drive cycle is established.Simulation analysis of the influencing factors for the driving range of electric logistics vehicles is carried out.The impact of seven factors on the driving range is studied,including power battery capacity,full load mass,rolling damping coefficient,air damping coefficient,drive motor efficiency,transmission system efficiency and power battery discharge efficiency.(3)The theoretical research on the vehicle analysis of the pure electric logistics vehicle and the selection of the power transmission system are studied.The indicators of vehicle parameters and performance are made based on project indicators,and the force analysis and performance analysis of the vehicle are conducted.According to the research on domestic urban drive cycles,the CHTC-LT drive cycle are selected.Power system is selected from drive motor and power battery.The transmission system is selected from three aspects: transmission ratio selection,gear number selection and transmission ratio range determination.Finally,a three-speed transmission system with a top gear is selected.(4)The parameter matching method of the power transmission system is proposed.Firstly,a data processing method for CHTC-LT drive cycle is established referring to NEDC drive cycle by establishing data processing rules and data processing principles.The power requirements under different operating conditions are calculated based on original CHTC-LT drive cycle data,and the parameter matching method of the drive motor is established.A power battery parameter matching method is established by matching the power battery capacity requirements.Secondly,a transmission ratio optimization method based on multi-island genetic algorithm is established.A vehicle simulation model establishment method is proposed.By considering the vehicle speed,drive motor,power battery and transmission system,a method on verifying the performance of vehicle simulation model is established.A method on the establishment of co-simulation model is proposed,the optimization algorithm is selected,the preoptimization setting is carried out,and finally the genetic algorithm is used for transmission ratio optimization.The driving range is set as the optimization goal,and the results is verified.(5)The parameter matching results of the pure electric logistics vehicle are as follows.The data processing for the CHTC-LT drive cycle and its diagram are completed.The performance parameters of drive motor are obtained after determining the power value under the CHTC-LT drive cycle,the capacity and other parameters of the power battery are matched.The CHTC-LT drive cycle data is called and the performance simulation is performed to verify the correctness of the simulation model.The co-simulation model is established and the parameters of the multi-island genetic algorithm are set up.The transmission ratio value of the three-speed transmission system is obtained after optimization.It is concluded that the driving range is increased by 4.83% and 6.86% respectively,and the improvement of driving range by the transmission ratio optimization is verified.The research work is meaningful for the parameter matching method of the power transmission system for the pure electric logistics vehicle,and also provides a reference for the simulation research of the pure electric logistics vehicle. |
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