| In the era of the pursuit of harmonious coexistence between man and nature,the development of energy-saving and environmentally-friendly vehicles has become an inevitable choice for the global automotive industry.Electric vehicles use a clean power source,which can get rid of dependence on oil,will not pollute the environment,and become the mainstream direction of the automobile development industry.As a key component of pure electric vehicles,the functional safety and logical robustness of the battery management system will directly affect the overall vehicle safety.The automotive market is in an era of rapid updates.Early verification requirements for ECU software are gradually increasing.During the controller development cycle,no physical prototype is available about 60% of the time,resulting in a longer development cycle.How to ensure the functional safety of the battery management system while taking into account the development cycle is a key issue to be solved urgently.This topic discusses the research background and significance of battery management system,and analyzes the main functions of BMS in detail.Based on the above research,the research content of the thesis is determined: battery remaining power estimation and fault management.According to the design requirements of the platformized BMS,a detailed research plan was formulated,the two major functional models of BMS were completed,and a set of BMS control strategy model verification system in the early development stage was established.The verification system can shorten the R & D cycle from the perspective of functional simulation testing,while ensuring the safety and reliability of functions.The thesis mainly carried out the following work:1.Build a reliable battery simulation model.A second-order equivalent circuit is used as a prototype,and the parameters in the model are identified from real test data;the test object is a26800 cylindrical lithium ion battery;the test method is the HPPC pulse discharge characteristic test;the parameter identification method is the least squares algorithm;the model The implementation method is to build a power battery model in the MATLAB / Simulink environment and inject the parameters into the battery model to complete the model construction.2.Study the estimation of the remaining battery power.Based on a full comparison of the advantages and disadvantages of the commonly used estimation methods and the applicable range,the unscented Kalman filter algorithm is used to estimate the SOC.A program forestimating the remaining battery power using the unscented Kalman filter is developed in the Matlab environment.The running results are compared with the actual test results to verify the accuracy of SOC estimation.3.Based on the requirements of functional safety,the control strategy of the fault management function in the battery management system is designed and developed,and the concept,architecture of the functional safety and the specific content of the BMS fault management are fully studied.According to the design requirements of functional safety,the control strategy of the BMS is designed,which specifically includes: conducting hazard analysis and risk assessment of possible incidents,determining the safety objectives and ASIL levels of each major function,and designing the functional safety scheme of the system based on the assessment results.In the Simulink / Stateflow environment,build models of functional fault-based modules and high-voltage power-on and power-off modules.4.According to the existing simulation test technology,determine the functional verification scheme of BMS in the early stage of development,and design test cases and test procedures.The specific test process is: in the model development phase,the model-in-the-loop test technology is used to verify the control strategy,and the rapid control prototype(RCP)and hardware-in-the-loop test integration solution is used to verify the control strategy online and verify the results to ensure System functional safety. |
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