| With the continuous improvement of China’s comprehensive national strength and environmental protection,new energy vehicles have attracted more and more attention.Lithium batteries are widely used in the field of electric vehicle power batteries due to their high energy density,low self-discharge rate and no memory effect.Usually electric vehicles require relatively high power,which cannot be met by a single-cell lithium battery.In order to meet the working requirements of electric vehicles,many single lithium batteries are generally connected in series to form a battery pack.Due to the internal factors of the battery,the battery pack is inconsistent,and this inconsistency will reduce the overall available capacity of the battery pack.In order to improve the inconsistency of the battery pack,this paper designs a balanced topology and control strategy based on a bidirectional DC-DC converter by analyzing and studying the current balance topology and control methods.The specific research contents are as follows:Firstly,the existing equalization technology is analyzed and improved on the basis of bidirectional forward converter.A series battery pack equalization topology based on Bidirectional DC-DC converter is designed,its working principle is analyzed,and then the main parameters in the equalization circuit are calculated.Secondly,according to the characteristics of the proposed equilibrium topology,combined with the current equilibrium strategy.The improved extreme value comparison method is used as the equilibrium control strategy in this paper.The Simulink equilibrium system simulation platform is built,and SOC is used as the equilibrium variable.The feasibility of the proposed control strategy is verified by simulation experiments.Finally,the software and hardware of the balanced system are designed,and the experimental platform is built according to the balanced system.Taking SOC as the equalization variable,through the equalization experiments in the discharge state,the charge state and the static state,the equalization experiment results show that the proposed equalization system can effectively eliminate the inconsistency of the battery pack,and the effectiveness of the equalization system is verified. |
