Research On Fault Diagnosis Of Electric Vehicle VCU Based On UDS Protocol

At present,PEV(pure electric vehicles)as an important part of the new energy vehicles,has flooded the market,but most of the Pure Electric Vehicles in the application layer diagnostic and security control strategy related to the mature traditional car is also slightly inadequate.Due to complex electrical components and high-voltage electrical components of Pure Electric Vehicles,it is difficult to obtain information on vehicle failure in the absence of diagnostic functions and safety control strategy.Beside,Pure Electric Vehicles failure will cause serious consequences.At present,CAN bus-based vehicle fault diagnosis system is becoming the most basic requirement of intelligent and Internet.Therefore,it is very necessary to develop the corresponding fault diagnosis system for Pure Electric Vehicles power system,which has great value and significance to improve the accuracy and reliability of vehicle fault diagnosis.The object of this research is Dongfeng E30 L pure electric vehicle,based on the unified diagnostic service(UDS)protocol,this paper has developed a fault diagnosis system for PEV vehicle controller,including CAN network simulation system and PC terminal fault diagnosis system.It has achieved real-time fault diagnosis,fault handling,fault storage and interactive diagnostic communication and other functions.The PC-side fault diagnosis system is more flexible and powerful than the traditional diagnostic instrument.In this paper,the ISO15765 and ISO14229(UDS)protocols of the CAN bus are studied.The fault diagnosis architecture of CAN bus is determined,the data link layer,the physical layer,the network layer and the application layer are defined.Then,based on CANoe software,the CAN network simulation system of vehicle controller is established,and the data and fault information of Pure Electric Vehicles vehicle controller are monitored and retrieved in real time by vehicle CAN network.Secondly,based on the existing Dongfeng E30 L pure electric vehicle controller,the lower computer VCU has been programmed and added a fault diagnosis service function.The development of the subsystem is completed to realize the storage of the fault information by the VCU and the response to the read and clear fault diagnosis service.Finally,the fault diagnosis system of PC-based pure electric vehicle is introduced in detail,And through CANoe software simulation test,semi-physical simulation test and real vehicle test,which verify the PC-side fault diagnosis system of effectiveness and reliability.