CN-121984172-A - Battery cluster equalization control system and control method

Abstract

The invention discloses a battery cluster balance control method and a battery cluster balance control system, which comprise the steps of obtaining the standing time of a battery cluster, the residual capacity of the battery cluster and the monomer residual capacity of each single battery in the battery cluster, and executing a balance algorithm based on the residual capacity when the standing time of the battery cluster reaches a first preset time and the residual capacity of the battery cluster is lower than a first preset value, wherein the executing the balance algorithm based on the residual capacity comprises the steps of calculating the difference value between the maximum monomer residual capacity and the minimum monomer residual capacity in each battery pack and judging whether the difference value is greater than or equal to a second preset value, and executing an in-pack active balance algorithm based on the residual capacity and executing a battery pack passive balance algorithm based on the residual capacity when the judgment result of at least one battery pack is yes, so that the battery cluster balance control method and the battery cluster balance control system can have higher balance efficiency and faster balance speed.

Inventors

• DU FANGSUO
• WANG ZHENG

Assignees

• 杭州协能科技股份有限公司

Dates

Publication Date

20260505

Application Date

20260325

Claims (10)

1. 1. A battery cluster equalization control method for controlling an active equalization circuit and a passive equalization circuit in a battery equalization system to equalize at least two battery packs in a battery cluster, each battery pack including a plurality of series-connected unit cells, the equalization control method comprising: obtaining standing time of a battery cluster, residual capacity of the battery cluster and monomer residual capacity of each monomer battery in the battery cluster; when the standing time of the battery cluster reaches a first preset time and the residual electric quantity of the battery cluster is lower than a first preset value, executing an equalization algorithm based on the residual electric quantity, wherein, The performing of the remaining power based equalization algorithm includes: calculating a difference value between the maximum monomer residual capacity and the minimum monomer residual capacity in each battery pack, and judging whether the difference value is larger than or equal to a second preset value; and when the judging result of at least one battery pack is yes, executing an in-pack active equalization algorithm based on the residual electric quantity on each battery pack with the judging result of yes, and executing a battery pack passive equalization algorithm based on the residual electric quantity.
2. 2. The equalization control method according to claim 1, further comprising executing a cell passive equalization algorithm based on a remaining amount of electricity for the entire battery cluster when the determination result of all the battery packs is no.
3. 3. The equalization control method of claim 2, further comprising: after the balance algorithm based on the residual electric quantity is executed, judging whether the active balance circuit is started or not; when the active equalization circuit is not started, acquiring the voltage of each battery pack, the single voltage of each single battery and the standing time of the battery equalization system in the battery cluster, and When the difference between the maximum voltage and the minimum voltage of at least two battery packs is larger than a third preset value, or the standing time of the battery balancing system reaches a second preset time, and the difference between the maximum monomer residual capacity and the minimum monomer residual capacity of the monomer batteries in at least one battery pack is larger than or equal to the second preset value, a voltage-based balancing algorithm is executed, Wherein the voltage-based equalization algorithm comprises: Performing an intra-stack active equalization algorithm based on voltage for each of the battery stacks and determining whether the active equalization circuit performs intra-stack active equalization for at least one of the battery stacks, and And when the judgment result is yes, executing a battery pack passive equalization algorithm based on the voltage.
4. 4. The equalization control method of claim 3, further comprising: After the balance algorithm based on the residual electric quantity and the balance algorithm based on the voltage are executed, judging whether the active balance circuit is started or not; and executing a voltage-based single battery passive equalization algorithm when the active equalization circuit is not started.
5. 5. The equalization control method of claim 4, wherein the active equalization circuit comprises a plurality of intra-group active equalization units, one intra-group active equalization unit is disposed between two adjacent single cells in each battery group, and the residual capacity/voltage-based intra-group active equalization algorithm comprises: calculating the average residual quantity/average voltage of the single batteries in each battery pack; calculating the difference value between the monomer residual capacity/voltage of each single battery and the average residual capacity/voltage of the battery pack where the monomer residual capacity/voltage of each single battery is positioned by taking the battery pack as a unit, and calculating the residual capacity/voltage dispersion corresponding to each single battery according to the difference value; Taking a battery pack as a unit, obtaining the maximum residual capacity/voltage deviation, calculating the balance duty ratio of each in-pack active balancing unit in each balancing period according to the residual capacity/voltage deviation corresponding to the single battery closer to the negative electrode of the battery pack in the two single batteries connected with each in-pack active balancing unit and the maximum residual capacity/voltage deviation of the battery pack where the residual capacity/voltage deviation is located, determining the balance time of each in-pack active balancing unit according to the residual capacity deviation of the single battery closer to the negative electrode of the battery pack in the two single batteries connected with each in-pack active balancing unit, the balance current of the in-pack active balancing unit and the equivalent working coefficient, The equivalent working coefficient of the active equalization unit in each battery pack is determined according to the difference between the maximum monomer residual capacity and the minimum monomer residual capacity in the battery pack, and the equalization direction of the active equalization unit in each battery pack is determined according to the corresponding residual capacity/voltage deviation sign of the monomer battery closer to the negative electrode of the battery pack in the two connected monomer batteries.
6. 6. The equalization control method of claim 4, wherein the passive equalization circuit comprises a plurality of passive equalization units, one passive equalization unit is connected between the positive electrode and the negative electrode of each single battery, and the battery pack passive equalization algorithm comprises: Calculating the average residual capacity/voltage of the single batteries in each battery pack, and obtaining the minimum average residual capacity/voltage; And calculating the difference value between the average residual capacity/voltage and the minimum average residual capacity/voltage of the single batteries in each battery pack, and calculating the passive equalization time of the battery pack when the difference value is larger than a fourth preset value/a fifth preset value, wherein the passive equalization units connected with each battery pack are simultaneously opened or closed.
7. 7. The equalization control method of claim 6, wherein the cell passive equalization algorithm comprises: Calculating the minimum monomer residual capacity/monomer voltage of the single batteries in the battery cluster; And calculating the difference value between the average residual capacity/voltage of each single battery and the cluster minimum single residual capacity/voltage, and calculating the passive equalization time of the single battery when the difference value is larger than a sixth preset value/a seventh preset value.
8. 8. The equalization control method of claim 4, wherein the voltage-based equalization algorithm and the voltage-based cell passive equalization algorithm are updated every third preset time.
9. 9. A battery cluster equalization control system for performing the equalization control method of any of claims 1-8, the equalization control system comprising: the sampling unit is used for obtaining the standing time of the battery cluster, the residual capacity of the battery cluster, the monomer residual capacity and the monomer voltage of each monomer battery in the battery cluster and the standing time of the battery balancing system; and the algorithm execution unit is used for selecting and executing one of a balance algorithm based on the residual electric quantity, a balance algorithm based on the voltage and a passive balance algorithm based on the single battery of the voltage according to the signals sampled by the sampling unit so as to control the active balance circuit and the passive balance circuit to execute corresponding balance operation.
10. 10. The equalization control system of claim 9, wherein the algorithm execution unit updates every third preset time while executing the voltage-based equalization algorithm and the voltage-based cell passive equalization algorithm.

Description

Battery cluster equalization control system and control method Technical Field The invention relates to the technical field of battery equalization, in particular to a battery cluster equalization control system and a control method. Background The lithium battery comprises three types of lithium battery cells, a lithium battery pack and a lithium battery cluster according to the packaging form. The inconsistency of the single batteries is gradually expanded along with the use of the battery pack, on one hand, the difference of the ageing rates of different single batteries is influenced by factors such as uneven temperature distribution of the use environment, difference of charge and discharge current distribution and the like, partial single batteries are accelerated to age, so that the capacity decay speed of the single batteries is faster than that of other batteries, and on the other hand, the small difference of initial parameters among the single batteries is continuously amplified along with the increase of the charge and discharge cycle times, so that the inconsistency of the parameters such as voltage, capacity, internal resistance and the like of each single battery is more remarkable. The inconsistency between the single cells can affect the overall performance of the battery pack, and also affect the service life of the single cells. In order to solve the above problems, various equalization schemes are proposed in the prior art, and the schemes are mainly divided into two major categories, namely active equalization and passive equalization. The core principle of the passive equalization mode is that the voltage of each single battery in the battery pack is monitored in real time through a voltage detection module, when the voltage of one or more single batteries is detected to be obviously higher than that of other single batteries, energy consumption elements (such as resistors) in an equalization circuit are controlled to be conducted, and redundant electric energy of the single battery with higher voltage is consumed in a heat energy mode until the voltages of the single batteries tend to be consistent. The active equalization mode is to identify the single battery with higher voltage and the single battery with lower voltage through the voltage detection module, and then directionally transfer the electric energy of the single battery with higher voltage to the single battery with lower voltage by using an energy transfer device (such as an inductor, a capacitor, a transformer and the like) in the active equalization circuit, so that the high-efficiency transfer and redistribution of the electric energy among different single batteries are realized, and the consistency of the battery pack is improved rapidly. However, the existing passive equalization scheme has lower efficiency and serious energy waste, while the active equalization scheme has higher efficiency but has the problem of too slow equalization speed. Based on this, a new battery cluster equalization control system and control method have been proposed to solve the above-mentioned problems. Disclosure of Invention In view of the foregoing, an object of the present invention is to provide a battery cluster equalization control system and control method, which can simultaneously have higher equalization efficiency and faster equalization speed. According to one aspect of the invention, an equalization control method for a battery cluster is provided, which is used for controlling an active equalization circuit and a passive equalization circuit in a battery equalization system to equalize at least two battery packs in the battery cluster, wherein each battery pack comprises a plurality of single batteries connected in series, the equalization control method comprises the steps of obtaining the standing time of the battery cluster, the residual capacity of the battery cluster and the single residual capacity of each single battery in the battery cluster, executing an equalization algorithm based on the residual capacity when the standing time of the battery cluster reaches a first preset time and the residual capacity of the battery cluster is lower than a first preset value, calculating the difference between the maximum single residual capacity and the minimum single residual capacity in each battery pack, judging whether the difference is larger than or equal to a second preset value, and executing an intra-pack active equalization algorithm based on the residual capacity for each battery pack judged as yes when the judgment result of at least one battery pack is yes, and executing a passive equalization algorithm based on the residual capacity of the battery pack. Optionally, when the judging results of all the battery packs are no, executing a single battery passive equalization algorithm based on the residual electric quantity for the whole battery cluster. The equalization control method further comprises the steps of jud