Design Of Battery Management System And Research On Charging Equalization For EV

As the substituted scheme of traditional fuel automobiles, Electric Vehicle (EV) becomes the focus of recent research in Automobile Industrials. Power battery and battery management is the bottleneck in the development of EV, and the limited energy for long distance driving makes it difficult to satisfy the need of market and customers. In the condition that the cell-capacity of given battery is determined, the effective supervision and management of battery stack could prolong the battery stack's life, and therefore, the driving distance could be extended profoundly.In this thesis, based on the operation characteristics of Li-ion battery stacks, a smart Battery Management System (BMS) is designed. The system adopts the distributed control structure, which accomplishes the management function of the system. At the beginning, the function and structure of the system is introduced in general, and the hardware design of each module in the system is given in detail. In addtion, the CAN net of BMS is constructed to realize the communication of all nodes in the system, and the CAN application layer protocol is designed to make the command and data bytes transferred methodically. Moreover, based on the hardware resource of the system, one more stand-alone CAN controller is extended to interface with the whole EV CAN bus.The inconsistency among all cells will deteriorate when connected in series, and the battery stack's efficiency and life will decrease consequently. Charging equalization, as the effecitive method in minishing the imbalance of battery cells, could prolong the battery stack's life dramatically. The charging equalization scheme is introduced in general at first, and the half-bridge inversion co-axil multiwinding transformer structure is selected as the target method. By using Matlab, the battery simulation module is designed, and the charging equalization circuit is built. With such module and circuit, the equalizing process is simulated to prove the converging of differences among cells. Finally, based on the simulation results, the characteristic of such equalizing topology and its application is explained further.