Research On Power Battery Energy Balance Management Strategy

In order to improve the inconsistency between batteries,prolong the service life of batteries,increase the actual available capacity and improve the energy utilization rate of power batteries.The main contents of this paper are as follows:(1)The battery performance of ternary lithium-ion batteries was tested,and it was found that the charge-discharge characteristic voltage of the batteries was positively related to the capacity;the capacity was not affected by the charge-discharge ratio,but was obviously affected by the high or low temperature;the internal resistance increased with the decrease of SOC,and increased with the decrease of temperature.The influence of the measured parameters on the inconsistency of batteries is analyzed,and the means to alleviate the inconsistency of batteries are briefly described.The energy balance management of batteries is introduced.(2)With the working voltage as the equalization variable,the maximum voltage is chosen as the starting and stopping conditions of passive equalization,and the average voltage difference of battery pack is chosen as the starting and stopping conditions of active equalization,and the multi-inductance equalization topology with good scalability and fewer devices is selected as the equalization circuit.A scheme of passive equalization for single battery under battery charging and active equalization for battery pack under discharging/stationary condition is proposed.(3)The passive equalization module of battery cell and the active equalization module of battery pack are designed.Passive module includes battery protection and passive equalization circuit design and device selection.The active module is divided into software and hardware design.The hardware design includes the selection of the main control chip,the design of the minimum system,the design of the system regulated power supply,thedesign of the battery voltage monitoring module and the design of the active equalization circuit.The control flow chart of the software is introduced in the software part.(4)Finally,based on the battery pack of the electric bicycle,the experiments of passive equalization and active-passive equalization are carried out.The results show that the slight imbalance of the battery can be achieved by passive equalization.When the battery or battery is seriously imbalanced,the energy transfer should be carried out by active equalization first,and then adjusted by passive equalization as a whole.Experiments show that the equalization strategy is feasible,and the equalized battery voltage is basically restored and can be used normally.