CN-122001063-A - Battery pack-based single cell capacity difference balancing method and device

CN122001063ACN 122001063 ACN122001063 ACN 122001063ACN-122001063-A

Abstract

The application provides a single cell capacity difference balancing method and device based on a battery pack, relates to the technical field of battery packs, and solves the technical problem that the prior art is difficult to adapt to the capacity of a single cell under irregular charge and discharge of the battery pack. The method specifically comprises the steps of obtaining a first curve and a second curve, wherein the first curve is a charging voltage curve of a first monomer, the second curve is a charging voltage curve of a second monomer, calculating the capacity difference between the first monomer and the second monomer based on the first curve and the second curve, and balancing the energy of the first monomer and the energy of the second monomer based on the capacity difference. The application is used for cell energy difference equalization of the battery pack.

Inventors

ZHU QINGCHEN
BAO CHENGZHI
WANG BOFAN
YANG YANG
Su Henian
GAO PINGPING

Assignees

安徽优旦科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260210

Claims (10)

1. The cell capacity difference balancing method based on the battery pack is characterized by comprising the following steps of: Acquiring a first curve and a second curve, wherein the first curve is a charging voltage curve of a first monomer, and the second curve is a charging voltage curve of a second monomer; calculating the capacity difference between the first monomer and the second monomer based on the first curve and the second curve; and balancing the energy of the first monomer with the energy of the second monomer based on the capacity difference.
2. The method of claim 1, wherein SOH and internal resistance of the first monomer and the second monomer are the same.
3. The method of claim 2, wherein the first curve conforms to the shape of the second curve, and wherein translating the first curve coincides with the second curve.
4. The method of claim 3, wherein calculating the difference in the capacities of the first monomer and the second monomer based on the first curve and the second curve comprises: Calculating a charging energy difference between a first curve and a second curve in charging time, wherein the charging energy difference is calculated in a time dimension and the charging energy difference is calculated in a voltage dimension; And calculating the capacity difference based on the charging energy difference and a conversion voltage value.
5. The method of claim 4, wherein said calculating said charge energy difference in a time dimension comprises: determining the charging start time and the charging end time as the first integral upper and lower limits; taking the instantaneous voltage difference value of the first curve and the second curve as a product item, and combining the charging current to construct a first product function; and integrating the first integrated function within the upper and lower limits of the first integration to obtain the charging energy difference.
6. The method of claim 4, wherein said calculating said charge energy difference in a voltage dimension comprises: determining the minimum voltage value of the second curve and the maximum voltage value of the first curve in the charging time as the upper and lower limits of the second integration; taking the instantaneous time difference value of the first curve and the second curve under the same voltage as a product item, and constructing a second product function by combining the charging current; and integrating the second integrated function within the second integration upper and lower limits to obtain the charging energy difference.
7. The method of claim 4, wherein the converted voltage value is a difference between a maximum voltage value of the first curve and a minimum voltage value of the second curve.
8. The method of claim 4, wherein calculating the difference in the capacities of the first monomer and the second monomer based on the first curve and the second curve further comprises: Dividing the voltage values of the first curve and the second curve at equal intervals; calculating the average value of time deviation values corresponding to all voltage values, wherein the time deviation values are the time difference values corresponding to the first curve and the second curve under the same voltage value; and calculating the product of the average value of the time deviation value and the charging current to obtain the capacity difference.
9. The method of claim 1, wherein the second monomer is the monomer with the lowest voltage value at the same charge time in the charge voltage curve.
10. The single cell capacity difference balancing device based on the battery pack is characterized by comprising a communication unit and a processing unit; The communication unit is used for acquiring a first curve and a second curve, wherein the first curve is a charging voltage curve of a first monomer, and the second curve is a charging voltage curve of a second monomer; the processing unit is used for calculating the capacity difference between the first monomer and the second monomer based on the first curve and the second curve, and balancing the energy of the first monomer and the energy of the second monomer based on the capacity difference.

Description

Battery pack-based single cell capacity difference balancing method and device Technical Field The application relates to the technical field of battery packs, in particular to a single cell capacity difference balancing method and device based on a battery pack. Background The balance of the cell capacity of the battery pack is a key technology for guaranteeing the safety and service life of a battery system under the scenes of energy storage, vehicles and the like, the conventional battery balance scheme generally needs to test and determine the cell capacity in advance, or calculate the balance of each cell by means of a charge curve translation method, and the balance calculation is realized by depending on a complete charge curve of the battery from a complete emptying state to a full state and by a key line segment matched with the curve, but in irregular charge and discharge scenes of two-wheel electric vehicles and the like, the battery is charged after being completely emptied, so that the charge curve is incomplete, the curve translation method is difficult to match the key line segment, and the cell capacity and the corresponding balance cannot be accurately calculated, so that the technical problem that the battery pack is difficult to adapt to the balance of the cell capacity under irregular charge and discharge exists in the prior art. Disclosure of Invention The application provides a single cell capacity difference balancing method and device based on a battery pack, which solve the technical problem that the single cell capacity is difficult to be balanced under irregular charge and discharge of the battery pack in the prior art. In order to achieve the above purpose, the application adopts the following technical scheme: The first aspect provides a battery pack-based single-cell capacity difference balancing method, which comprises the steps of obtaining a first curve and a second curve, wherein the first curve is a charging voltage curve of a first single cell, the second curve is a charging voltage curve of a second single cell, calculating capacity difference between the first single cell and the second single cell based on the first curve and the second curve, and balancing energy of the first single cell and energy of the second single cell based on the capacity difference. Based on the technical scheme, in the cell capacity difference balancing method based on the battery pack, the absolute capacity of the cell is not required to be tested in advance, the capacity difference can be calculated and the energy balance can be realized only by acquiring the charging voltage curves of the two cells, the irregular charging and discharging scene that the battery is not completely emptied is effectively adapted, the dependence of the prior art on the complete charging and discharging curve is avoided, the practicability of the method is obviously improved while the balancing accuracy is ensured, and the safety, stability and service life of a battery system are further maintained. With reference to the first aspect, in one possible implementation manner, SOH and internal resistance of the first monomer and the second monomer are the same. With reference to the first aspect, in a possible implementation manner, the shape of the first curve is consistent with that of the second curve, and the first curve may be overlapped with the second curve when the first curve translates. With reference to the first aspect, in one possible implementation manner, calculating the capacity difference between the first monomer and the second monomer based on the first curve and the second curve includes calculating a charge energy difference between the first curve and the second curve in a charging time, including calculating the charge energy difference in a time dimension and the charge energy difference in a voltage dimension, and calculating the capacity difference based on the charge energy difference and the converted voltage value. With reference to the first aspect, in one possible implementation manner, calculating the charging energy difference in a time dimension includes determining a charging start time and a charging end time as a first integral upper limit and a first integral lower limit, using an instantaneous voltage difference value of the first curve and the second curve as an integral term, constructing a first integrated function in combination with a charging current, and integrating the first integrated function within the first integral upper limit and the first integral lower limit to obtain the charging energy difference. With reference to the first aspect, in one possible implementation manner, calculating the charge energy difference by using the voltage dimension includes determining that a minimum voltage value of the second curve and a maximum voltage value of the first curve in the charge time are second integral upper and lower limits, using an instantaneous time difference va