Research On Control Strategy And Characterization Analysis Of Multi-motor Coupled Propulsion System Of Electric Bulldozer

In recent years,with the development of new energy construction machinery,the research on its electric drive system technology has become an important topic.Crawler bulldozer is a kind of widely used shovel and transportation machinery.Relevant research shows that the application of electric drive technology in the drive system of bulldozer can effectively improve the performance of bulldozer.The configuration optimization of the multi-motor coupling drive system and the rational formulation of its control strategy have obvious effects on the energy saving and environmental protection of bulldozers.Therefore,the development and research of electric drive bulldozer has become a trend,and the research of its key technology has a great significance.Based on Jilin Province Science and Technology development plan project "Research on Coordinated Control of Multi-motor Coupled Drive System of Electric Drive Bulldozer"(20190201097JC),The key technology of multi-motor coupling drive system configuration and the control strategy of electric drive bulldozer has been systematically analyzed and studied in this thesis.Main research contents and achievements are as follows:(1)The terramechanics characteristics and vehicle dynamics characteristics of the bulldozer track are analyzed,and the multi-motor drive system simulation model is established.Firstly,according to the terramechanics characteristics of the bulldozer,the source of resistance during the bulldozer running is analyzed.Secondly,according to the driving characteristics of the bulldozer,the mathematical models based on the linear driving and steering of the bulldozer and the dynamics of the multi-planetary differential dynamic coupling drive system are established respectively.On this basis,the simulation model of electric drive bulldozer and multi-motor coupling drive system is established.(2)The driving control strategy of multi-motor coupling drive system under typical working conditions is studied.According to the driving characteristics of the bulldozer and the configuration of the multi-motor coupling drive system,the linear driving control strategy,steering control strategy and multi-motor coupling drive control strategy of the electric drive bulldozer are proposed to achieve the goal of adjusting the driving state of the drive motor according to the load torque.(3)The multi-motor coupling drive configuration of electric drive bulldozer based on a multi-planetary row power coupling mechanism is proposed with key parameter optimization.According to the driving characteristics of the crawler bulldozer,the drive system configurations based on single motor,double motor and multi-motor are proposed respectively,and the energy consumption simulation of the three drive system configurations under the same working condition is carried out.The simulation results are analyzed and evaluated.Through evaluating the power flow efficiency of the electric drive system of bulldozer,the influencing factors of no-load drive and clutch starting of the drive motor on the system efficiency are extracted.Dynamic programming method and discrete efficiency method are used to optimize and match the motor parameters of the drive system,and the optimal number of drive motors and the selection range of high efficiency interval of drive motors in the control process are studied.By analyzing the working state of each drive motor,the drive motor power ratio of multi-motor drive configuration is optimized.(4)A driving force optimization distribution control method of electric drive bulldozer based on track slip rate is proposed.Based on the test data of heavy and light load bulldozers,the driving characteristics of bulldozers under different working conditions are analyzed.With the minimum slip rate of the track on both sides as the optimization objective,the optimization objective function is established under the constraint condition that the tractive force of the bulldozer remains unchanged.By using the particle swarm optimization algorithm combined with hybridization algorithm to solve the objective function,the optimal distribution of the driving torque of the driving motor and the steering motor is obtained,and the traction efficiency of the bulldozer is improved.(5)The multi-motor coupling drive system principle prototype test bench is built,and the multi-motor coupling drive test is carried out.The control and data acquisition system based on Lab VIEW is constructed,and the corresponding hardware design and software development are completed.Based on the actual driving condition of the electric drive dozer,the multi-motor coupling drive bench test is carried out,and the data of input shaft torque,output shaft torque and clutch control signal are collected.The data analysis proves that the proposed multi-motor coupling drive scheme is feasible and can improve the energy efficiency of the electric drive bulldozer.In this thesis,the key technology of multi-motor coupling drive system of electric bulldozer is simulated and tested from several aspects.It contains theoretical analysis,configuration design,key parameter optimization,control strategy and driving force distribution.The results show that the multi-motor coupling drive configuration,the design method of key parameters and the control strategy proposed in this thesis can effectively improve the energy efficiency of the electric drive bulldozer.The proposed driving force distribution optimization method can effectively reduce the slip rate of the track on both sides of the bulldozer and improve the traction efficiency.The feasibility of the proposed multi-motor coupling drive configuration and control method is verified by experiments,which provides a new idea for the research of the key technology of multi-motor coupling drive and the development of new products.