Active equalization control method and system for lithium ion battery

Abstract

The invention relates to the technical field of battery management systems, in particular to an active equalization control method and system for the lithium ion battery. The lithium ion battery is provided with a plurality of single batteries which are connected in series, and the active equalization control method comprises the following steps: S1, estimating the initial value of the residual electric quantity of the lithium ion battery, and obtaining the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery inreal time; S2, according to the estimated value of the residual electric quantity of the lithium ion battery and the voltage detection value of the lithium ion battery, respectively calculating the average value of the residual electric quantity of the lithium ion battery and the average value of the voltage of the lithium ion battery; S3, according to the average value of the residual electric quantity and the average value of the voltage, judging the single batteries needing to be equalized; and S4, equalizing the single batteries needing to be equalized. The method has the beneficial effects that the precision and reliability of the equalization system can be improved, the use efficiency of the battery is improved, the service life of the battery is prolonged, the control method is simple, the requirement on the controller is reduced, and the system reliability is improved.

Description

technical field [0001] The invention relates to the technical field of battery management systems, in particular to an active equalization control method and control system for lithium-ion batteries. Background technique [0002] In the prior art, the voltage of a single cell in a lithium-ion battery is relatively small, and a plurality of battery cells are usually connected in series to form a battery pack to achieve the required high voltage. However, in the process of use, due to the The difference in the properties of the body and environmental factors such as temperature will lead to differences in the capacity of each battery cell. The capacity of the battery pack has a wooden barrel effect. When charging, it is limited to the battery cell with the highest capacity, and when discharging, it is limited to the battery cell with the lowest capacity. The imbalance between each battery cell will reduce the use of the single battery. Life, so the balance between the individ...

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Problems solved by technology

[0005] Among the above patents, the patent CN105140981A performs active equalization according to the estimated SOC. The accuracy of the UKF estimation method used in this paper depends on the accuracy of the battery electrical model and the calculation amount is relatively large. It is necessary to choose a simple and reasonable battery model and a faster calculation speed. processor, and the accuracy of SOC estimation will directly affect the accuracy of active equalization; patent CN107046313A balances the cells by comparing the difference of cell voltage, and then calculates the capacity required for battery equalization, only based on the difference of cell voltage The value is used as the basis to balance the battery, and the battery voltage will be affected by factors such as internal resistance and the environment, and the voltage difference cannot accurately reflect the unbalanced battery capacity; the patent CN107623343A judges whether Balance and use an external power supply to charge the monomer, although the complexity of software control is reduced, but an additional battery pack is required, which not only increases the cost, but also increases the size of the device

[0006] Therefore, need a kind of technical research that solves the single active equalization technology of lithium-ion battery in the prior art

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