Battery capacity and SOC estimation method based on charging curve difference of single batteries in battery pack
A charging curve and battery capacity technology, applied in the field of battery capacity and SOC estimation, can solve the problems of complex calculation and difficult implementation, and achieve the effect of saving time and improving efficiency
Active Publication Date: 2021-10-29
UNIV OF SHANGHAI FOR SCI & TECH
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Generally, the higher the accuracy achieved by the estimation method, the more difficult it is to realize, and the more complex the calculations required
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[0047] Two universal 123 lithium-ion batteries are selected. The actual capacity of battery 1 is 26.14Ah, and the internal resistance is 11.16mΩ. The actual capacity of battery 2 is 27Ah, and the internal resistance is 10.74mΩ. Connect them in series as a battery pack and charge them with a constant current. Two groups of experiments were conducted respectively, and the specific experimental steps were as follows:
[0048] Experiment 1 operation steps are:
[0049] Charge the two batteries separately at constant current and constant voltage to 100% SOC, then discharge battery 1 to 15% SOC at a constant current, discharge battery 2 to 10% SOC at a constant current, and then treat the two batteries as a battery pack Charge in series to obtain the charging curves of two single batteries. Battery 1 is the first to reach the cut-off voltage, as the reference unit, and battery 2 as the unit to be tested. Shift the voltage curve of the reference monomer downward by 3.64mV to obtai...
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The invention relates to a battery capacity and SOC estimation method based on charging curve differences of single bodies in a battery pack. The battery capacity and SOC estimation method comprises the following steps: 1) establishing a theoretical corresponding relation between the capacity and SOC and the slope and intercept of charging time interval difference curves of the single bodies; 2) based on the charging data, finding a first cell reaching a charging cut-off voltage of the battery pack as a reference cell, and selecting other cells (except the reference cell) as to-be-tested cells; 3) calculating the internal resistance difference between the reference monomer and the to-be-tested cells, and translating the reference cells charging curve up and down to obtain a reference monomer charging curve after the internal resistance difference is corrected; 4) obtaining a charging time interval difference curve of the reference monomer and the to-be-tested cells by using an interpolation method, and carrying out linear fitting to obtain a slope and an intercept; and 5) calculating the capacity and the SOC of the to-be-tested cells according to the theoretical corresponding relation between the capacity and the SOC and the slope and the intercept of the cells charging time interval difference curve.
Description
technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a method for estimating battery capacity and SOC based on differences in charging curves of individual cells in a battery pack. Background technique [0002] In recent years, with the increasing number of electric vehicles, it is estimated that the capacity and SOC of battery packs are conducive to improving the overall performance of the battery management system and ensuring the cruising range of electric vehicles. [0003] Most of the current battery capacity estimation methods, such as data-driven closed-loop capacity estimation methods and empirical model-based capacity open-loop prediction methods, mostly estimate the capacity of battery packs. In addition, some battery pack monomer capacity estimation methods, such as charging curve-based Consistency to estimate the capacity of a single battery pack is too complicated and not suitable for data processing in r...
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IPC IPC(8): G01R31/387G01R31/389G01R31/396
CPCG01R31/389G01R31/387G01R31/396Y02E60/10
Inventor 郑岳久庞康欧阳明高韩雪冰周龙厉凯潘伟民李彬
Owner UNIV OF SHANGHAI FOR SCI & TECH