Research On SCR System Control Software Of Diesel Engine Based On MATLAB/Simulink

Diesel engine is widely used in agroforestry,transportation and military fields by virtue of its strong driving force,better economy,wide power range,good maneuverability,high reliability,long service life and convenient maintenance.However,diesel engines have higher NO_x emissions compared to gasoline engines,and NO_x would do great harm to the environment and the human body.With the gradual improvement of the awareness of the environment,emission regulations are also updated.The technology of SCR has become the main aftertreatment technology of diesel engine in that it has advantages on better emission reduction,less structural change of engine body and low requirement of sulfur content of fuel.At present,SCR products are basically monopolized by foreign enterprises.Those products are highly expensive and the core technology of China's SCR system is still relatively outdated,the research on SCR control system has great significance.In this paper,the modular design concept and the V-shaped process which has been commonly used in the automotive electronics industry,are taken into account to develop a common air-assisted SCR control system.Firstly,we develop the underlying toolkit for the target chip.Secondly,we set up the SCR control system algorithm model by MATLAB / Simulink based on our control strategy.Then,the target system is configured to make the control algorithm model automatically generate the C code.Finally,we use drive test,logic test,accuracy test and integration test to verify the SCR system control software.The main research work and achievements include: 1)Completing the development of the underlying driver kit,target system configuration.According to the requirement for the freescale chip MC9S12XS128 and SCR system used in the research,the S-function module is used to encapsulate the underlying driver,configure the target system.Customizing the code generation process through the script file,realize the participation of the underlying driver in the overall algorithm modeling and the one-click type of C code generation.The compiler can be called automatically.Due to the low rate of the error in the generated code and the formal specification,this method can save a lot of time spent on software development.2)Completing the modular design according to the SCR system control algorithm.Data management module,user management module,urea injection quantity calculation module and task execution are four basic modules.Their respective duties are to collect SCR system data,determine the SCR system state,calculate the amount of urea injection and drive the corresponding actuator.3)Completing tests on module function and simulation bench verification.Each module of the SCR system control software is verified individually,its basic function has already been realized;results of the test on state machine showed it can realize the self-diagnostic function of the system.C code was generated automatically based on the control algorithm model and downloaded to the DCU then.We also built the simulation platform,established communication between upper computer and the DCU,designed the monitoring interface which can monitor and calibrate target parameters.In that case,this SCR system control software has considerable application value.