The Design Of Battery Management System Based On Can Bus

With the whole society advocating energy saving and emission reduction and appealing green life, electric vehicle can meet the requirements for lowing carbon and saving energy by virtue of its advantage of zero-emission. Since the lithium battery has the advantages like high energy density and eco-friendliness among the existent power batteries, many kinds of electric vehicle employ it as the source of power. However, electric vehicles require the power sources with high-voltage and high-power. Therefore a large number of lithium batteries have to be interconnected to form the battery pack,so that safety and consistence, the estimation of the remaining capacity, and the service life, etc to be the bottleneck problems hindering the use of power batteries. Under the above mentioned circumstances, this research mainly includes the following aspects to solve a series of problems in the management system of lithium batteries.(1) On the basis of studying the principle, characteristics and the network architecture of CAN-bus, this dissertation employs CAN-bus technology to collect and transmit dada in the battery management system.(2) This dissertation designs hardware circuit of CAN-Bus based on the platforms of ARM and Embedded Linux, develops device driver and application program, and finally completes the design of monitoring terminal.(3) In view of the features of the lithium battery, the dissertation has mainly explored three functions of the battery management system, namely the dada collection, cell balance and the monitoring and protection of the battery pack. Besides, it has designed the hardware circuit and the software program to achieve these functions.(4) On the basis of analyzing discharge characteristics of the lithium battery, this dissertation has compared different kinds of SOC measuring methods, and improved the impedance tracking algorithm considering the factors of resistance and temperature.Upon the completion of the basic contents of the design, the functions of all parts have been tested. The test results show that:the monitoring terminal can receive the data collected by the battery management unit via CAN-Bus within the required time; the battery management unit can monitor and protect the voltage and temperature of the battery pack; and realize the cell balance at both the state of charging and the static state. However, the circuit has shortcomings of the difficulties in the high-power, low-efficiency and short-working time. Therefore, the circuit and the algorithm need to be improved. And simulation of the improved impedance tracking algorithm by Matlab verifies the feasibility of the improved algorithm.