Research And Practice Of Model-based System Engineering In Power Bogies Of EMU

As an important part of the Electric Multiple Unit(EMU),the power bogie affects the safety and comfort of train operation.With the development of high-speed railways and intelligent manufacturing technology,the digital transformation of EMU products has become a major trend in developing China’s independent research and EMU technology.With the increase of overseas business and the improvement of people’s requirements for ride comfort,the development of power bogies with multiple models,fast iteration and increasingly complex needs has emerged,the traditional text-based system engineering design process has exposed the ambiguity of design information,long demand change cycle,difficulty in collaboration,etc.,which has become one of the obstacles to its digital transformation.Because of such urgent R&D problems,this paper proposes to adopt the Model-Based Systems Engineering(MBSE)theoretical design method in the design process of power bogies,establish a digital model of power bogie,analyze and verify the correctness of the model,and explore the digital transformation of power bogie.Based on MBSE design theory,this paper proposes an overall analysis process integrating modeling analysis and simulation verification.In Magicdraw software,Sys ML language is used to realize the modeling and analysis of power bogies through the continuous evolution and iteration of four hierarchical models:business layer,functional layer,logic layer and physical layer.First,the demand analysis of the power bogie is carried out,and the full coverage of functional requirements is achieved by establishing a requirements-use case traceability matrix;Second,the power bogie traction,braking and vibration damping functions are mainly used to model the functions to obtain accurate hierarchical functions;Third,analyze the logical composition of the power bogie and establish a logical architecture;Fourth,the physical function is obtained through the function definition analysis method,the physical components are defined,and then the physical architecture of the power bogie is established.Finally,in Magicdraw and MATLAB/Simulink software,the logic simulation and performance simulation of the power bogie design model are carried out,and the result of the vibration acceleration of the car body≤2.5m/s~2is obtained,and the smoothness index is calculated to reach the"excellent"range of level 1,which meets the functional and performance requirements of the power bogie,and verifies the correctness of the power bogie architecture model.Through the traceability matrix,the models generated in the entire design process are associated,which ensures the strong traceability between the model elements in the design process,facilitates the unified management of the model,avoids the omissions caused by changes through the automatically generated change impact relationship model,and forms a closed loop in the entire design process.Using the MBSE theory and method for the design of power bogies can result in a more accurate description of the power bogie and obtain clearer hierarchical relations among models.Furthermore,when design requirements change,it can respond quickly,screening out all model elements related to the changed requirements,which is more conducive to change impact analysis and the management of complex systems.The results show that compared with the text-based design method,the MBSE theoretical method has obvious advantages in the design and development of complex systems such as power bogies and has a positive role in promoting its digital transformation.