Analysis And Design Of The Function Safety For Pure Electric Vehicle Controller

With the rapid development of pure electric vehicles,the vehicle control system is becoming more and more complex,and the accompanying functional failure safety issues are also increasingly prominent.However,based on the traditional development method,it is unable to meet the requirements of ensuring the safety of the electronic control unit.Therefore,the concept of functional safety is introduced in the development of automotive ECU,and the safety problem in the development and application of the electronic control unit is fully guaranteed through the functional safety standard ISO26262.This standard proposes technical specifications and requirements related to functional safety in the development and design of ECU.Therefore,vehicle control technology should also consider functional safety as a key technology for electric vehicles.Based on the research of functional safety standards,this thesis analyzes the functional safety of vehicle controllers.Aiming at the problem that the vehicle controller is not perfect in hardware function safety and lack of monitoring and redundancy mechanism,the corresponding hardware architecture and software architecture are designed.Based on this,the corresponding security mechanism is designed,and the security mechanism software such as monitoring and redundancy is realized.Finally,through the HIL hardware-in-the-loop test platform,the signal input and output of the vehicle controller are simulated.The function test and fault injection test of the completed vehicle controller were carried out to verify the vehicle controller designed in this thesis.The main contents of this article are as follows:1.First,the functional safety standards were studied,and the standard content,vehicle safety life cycle and automotive safety integrity ASIL level were introduced.At the same time,according to the functional safety standards,the safety analysis of the vehicle controller is carried out by hazard analysis,DFMEA analysis and FTA analysis,and the corresponding safety requirements and technical requirements are obtained.Combined with the characteristics of the vehicle controller,the corresponding hardware architecture and software architecture are designed.2.Secondly,combined with the characteristics of signal processing functions,the signal processing functions of the vehicle controller are analyzed to obtain potential faults.Aiming at the above potential faults,the corresponding fault detection and processing mechanism is designed,and its functional modules are designed,simulated and implemented.3.Then combined with the characteristics of CAN network communication,further analyze the CAN communication function of the vehicle control from the hardware level,and obtain potential faults.The redundancy mechanism of the backup CAN is used to detect and process faults,and the functional modules are designed,simulated and implemented.4.Finally,a test bench was built on the hardware in the loop test platform to simulate network communication and signal input and output.And use the CAPL script language to write test cases,realize the automatic injection and recovery of HIL test platform failures,and perform functional test and fault injection test on the vehicle controller.The test results show that the hardware function can work normally under normal conditions and fault injection conditions.At the same time,the corresponding security mechanism can also detect the occurrence of the failure and redundantly process it.The fault detection rate is over 99%,and the maximum time for the system to switch to the safe state is 45.9ms,which meets the corresponding security requirements and security objectives.Therefore,it is verified that the vehicle controller designed based on the functional safety standard meets the relevant requirements of the functional grade ASIL D level,which improves the safety and reliability of the vehicle controller and embodies the practical value of the functional standard.