Design method of CAN BUS network communication structure for electric vehicle

Abstract

According to the communication structure of CAN BUS network on EV, this paper works out a SAE J1939 application layer protocol meet the system functional requirements, and designs the software and hardware for the system. First, design the CAN BUS work nod for EV, including the master node, the light node, air conditioning node, doors and instrument node, etc, and the draw the CAN BUS topology diagram. Meanwhile, according to the concrete situation of EV, work out an application layer protocol that consistent with the SAE J1939 protocol, and the information allocation table and message structure chart of CAN BUS network node is also presented. Secondly, design the hardware and software for the CAN BUS communication network. Hardware interface circuit mainly consist of CAN communication controller SJA1000, high-speed opt coupler 6N137 and CAN BUS driver 82C250, and design schematic circuit diagram for CAN bus system hardware. The software designs for CAN BUS network are mainly the design of CAN BUS data communication and exchange between nodes, and communication processing for switch-signal, analog signal. The design of software communication module includes CAN initialization unit, message sending unit, message receiving unit and the interrupt service unit. Finally, the CAN BUS network communication system the paper designed is applied to the new energy bus produced by CENS Energy-Tech Co., Ltd. which is dedicated in the Shanghai World Expo. From the battery voltage data collected when EV are running, we can see that the system is accurate, stable without number lost, frame dropping and transfer error in data communication. The design has practical value promoting the application of new energy vehicles.