Research On Hybrid Vehicle CAN Bus Network Characteristics

Compared with traditional vehicle, the CAN bus node equipments of hybrid electric vehicles are more complicated, and the communication between the nodes is more complex. This thesis analyzed the topology of hybrid electric vehicle control network and the calculation method of CAN bus communication performance, studied the hybrid power system CAN bus by building its simulation model, constructed a range extender hybrid vehicle power system CAN bus and verified its communication performance.The basic topology structures of the hybrid electric vehicle CAN bus system were determined in the thesis after analyzing the composition and distribution of electrical system. According to the analysis results of the characteristics of different topologies by simulating them in CANoe, a comprehensive scheme of hybrid electric vehicle CAN bus topology design was put forward with the peripheral bus of vehicle body system refined.The CAN message transmission model was established to analyze the transmission delay effected by bus arbitration, transmission error and the bit stuffing mechanism etc, and the thesis put forward a mathematical expression of the CAN message transmission pr ocess. According to the simulation result of the probability distribution of CAN message bit stuffing mechanism and the analysis of transmission error recovery, the CAN message transmission process mathematical expression was refined. Based on the analysis of the CAN message transmission process model, this paper derived a calculation method of the communication performance index.In order to analyze the main communication performance index of hybrid power system CAN bus under different baud rate and transmission error triggering probability, a CAN bus communication system with state models was established based on the theory of Finite State Machine(FSM).In this thesis, the CAN bus topology of range extender hybrid vehicle power system was designed, and the node communication protocol was formulated under SAEJ1939. A monitoring platform was developed with LabVIEW for the CAN bus communication performance experimental verification. The experimental result of the real CAN system and CANoe model is basically the same as the result of the mathematical model and the simulation model.