Research On Performance Optimization And Energy Management Of Hybrid Tractor-Trailer

Tractor-trailer has the operating characteristics of long haul distance and large volume.The fuel consumption is generally high,which not only leads to high operating costs,but also brings a heavy burden on the environment.Under the background of China’s carbon peak goal by 2030,it is of great importance to realize the engineering application of hybrid technology in the field of semi-trailer tractor.Based on the Research and development of hybrid system for super energy-saving heavy truck（No.2017YFB0103500）,the key project of the Ministry of Science and Technology on new energy vehicles,it is carried out on the research on performance optimization and energy management of engineering-oriented hybrid power system.The main contents are as follows:（1）A working condition construction method based on connectivity data is proposed.Taking the connectivity data as the research object,the original data are cleaned by using constraints of acceleration,slope and vehicle speed.The principal component analysis is performed on the segmented working condition data by the fixed-step intercept method to achieve dimension reduction.The influence of clustering number on clustering quality is evaluated from the perspectives of tightness,separation,effectiveness of clustering analysis.The maximum likelihood estimation is used to construct the scene conditions of semi-trailer tractors such as express,less-than-truck-load transportation,and coal transportation.The statistical results of the working condition parameters show that the error of the main characteristic parameters is less than 9%,which verifies the validity of the working condition construction.（2）An engineering-oriented hybrid performance optimization method under multiple constraints is proposed.The applicability of typical hybrid configuration is analyzed from the perspective of energy degree of freedom and mechanical degree of freedom.The applicable configuration of hybrid semi-trailer tractor is evaluated from the perspective of scene conditions,cost increment and engineering feasibility.The energy saving potential of hybrid configuration under subdivided conditions is qualitatively analyzed by condition identification method.AVL-cruise software is used to quantitatively analyze the fuel saving contribution of different hybrid functions.The cooperative optimization model of vehicle performance reachable domain boundary and performance parameters is established.Taking different scenarios as an example,the new cost recovery cycle of hybrid power after optimization of performance parameters is shortened by more than 15%.（3）A multi-mode energy management module is proposed in autonomous driving mode,and a dynamic programming algorithm optimization module is proposed in the predictive cruise mode.To define the working state and action sequence of corresponding key assemblies according to the actual scenario subdivided usage mode.To promote the stable and efficient operation of the engine,establish engine working objective optimization curve in autonomous driving mode.The motor dynamic torque is adjusted to make up for the shortcoming of lack of engine dynamic response precision.A dynamic programming algorithm module based on road information in predictive cruise mode is established.Based on the model,the rolling time domain update method is predicted.Methods such as sampling points near density and far dispersion,trajectory aggregation and classification,and reducing the reachable domain of hybrid power system are combined.The compression algorithm traverses the range to reduce computation.（4）Aiming at the service braking and auxiliary braking modes of hybrid semi-trailer tractor,the decoupling braking energy recovery scheme is proposed.The braking energy recovery model of hybrid coaxial parallel configuration is established,and the key factors affecting energy recovery efficiency are analyzed.Depending on electronic braking system,the parameter identification module is established.Under the premise of considering braking efficiency and braking safety,motor braking is preferred to improve the recovery rate of braking energy.In auxiliary braking mode,constant speed mode based on fuzzy PID algorithm and manual mode based on open loop control are proposed.The effectiveness of the auxiliary braking and the feasibility of the auxiliary decoupling braking scheme are verified.（5）The bench test and road test of the engineering-oriented hybrid semi-trailer tractor are carried out.The engineering feasibility and research effectiveness are verified by prototype test,bench test and road test.The bench test results show that the developed hybrid functions are verified by the actual message,and the error of energy consumption test data and simulation data under different working conditions is within 2%.The road test results show that the acceleration time of 0–80 km/h under full load is 58.44 s,and the maximum acceleration of auxiliary decoupling braking is 0.55 m·s^-2,which achieve the expected goal.By analyzing the fuel consumption data before and after the opening of the predicted cruise function,the fuel saving effect is increased by 4.01%,and the maximum planning time is 0.43 s,which meets the requirements of vehicle fuel saving and engineering application.