CN-121984173-A - Battery equalization control system and control method

CN121984173ACN 121984173 ACN121984173 ACN 121984173ACN-121984173-A

Abstract

The invention discloses a battery equalization control system and a control method, which are used for controlling an active equalization circuit and a passive equalization circuit to equalize at least two battery packs in the battery equalization system, wherein the battery equalization control method comprises the steps of obtaining the monomer voltage and/or the monomer residual quantity of each monomer battery in the at least two battery packs; and when the difference value corresponding to any battery pack is larger than a first threshold value, selecting to execute the active equalization algorithm, and when the difference value corresponding to all battery packs is smaller than or equal to the first threshold value, selecting to execute the passive equalization algorithm, thereby reducing the system oscillation problem caused by larger active equalization current.

Inventors

DU FANGSUO
WANG ZHENG
WU HONGYU

Assignees

杭州协能科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260325

Claims (10)

1. A battery equalization control method for controlling an active equalization circuit and a passive equalization circuit to equalize at least two battery packs in a battery equalization system, the battery equalization control method comprising: Obtaining the monomer voltage and/or the monomer residual quantity of each single battery in at least two battery packs; selecting and executing an active equalization algorithm or a passive equalization algorithm according to the difference between the maximum monomer residual capacity and the minimum monomer residual capacity of the monomer batteries in each battery pack, and Selecting to execute the active equalization algorithm when the difference value corresponding to any battery pack is larger than a first threshold value, selecting to execute the passive equalization algorithm when the difference value corresponding to all battery packs is smaller than or equal to the first threshold value, The active equalization algorithm comprises an active equalization algorithm based on the residual electric quantity and/or an active equalization algorithm based on voltage.
2. The control method according to claim 1, further comprising: Judging whether the active equalization circuit and the passive equalization circuit have faults or not, and When the active equalization circuit has faults, a passive equalization algorithm is executed according to the acquired monomer voltage and/or the monomer residual quantity, and When the passive equalization circuit has faults, an active equalization algorithm is executed according to the acquired monomer voltage and/or monomer residual quantity, The active equalization circuit comprises an intra-group active equalization circuit and/or an inter-group active equalization circuit, wherein the intra-group active equalization circuit is used for carrying out intra-group active equalization on each battery group, the inter-group active equalization circuit is used for carrying out inter-group active equalization on at least two battery groups, and the passive equalization circuit is used for carrying out intra-group passive equalization or inter-group passive equalization on at least two battery groups.
3. The control method according to claim 1, wherein when the intra-group active equalization circuit fails, an inter-group active equalization algorithm is performed on a battery group in which the cell having the highest voltage is not in the current battery group, in addition to the passive equalization algorithm; And when the inter-group active equalization circuit fails, executing an intra-group active equalization algorithm on the at least two battery groups in addition to the passive equalization algorithm.
4. The control method according to claim 1 or 2, further comprising: recording the depth of discharge of the battery equalization system in a preset time and/or a preset charge-discharge period, counting the number of times the depth of discharge is greater than a set threshold value, and And determining an equalization coefficient according to the count value, multiplying the equalization coefficient by the starting time of each inter-group active equalization unit and/or passive equalization unit obtained by executing an equalization algorithm to obtain the actual starting time of each inter-group active equalization unit and/or passive equalization unit, and multiplying the equalization coefficient by the maximum equalization time of a plurality of intra-group active equalization units corresponding to the same battery group obtained by executing the active equalization algorithm based on the residual electric quantity to obtain the actual maximum equalization time.
5. The control method according to claim 4, wherein the determining an equalization coefficient from the count value includes: Dividing multiple value ranges, creating a lookup table between the multiple value ranges and their corresponding equalization coefficients, and Determining the value range of the count value, searching the corresponding equalizing coefficient, Wherein the equalization coefficient is a value greater than zero and less than one, and the larger the count value is, the smaller the equalization coefficient corresponding to the count value is.
6. The control method according to claim 1 or 2, further comprising controlling the active equalization circuit to perform a corresponding active equalization operation according to first equalization data obtained by executing the active equalization algorithm when executing the active equalization algorithm, and controlling the passive equalization circuit to perform a corresponding passive equalization operation according to second equalization data obtained by executing the passive equalization algorithm when executing the passive equalization algorithm.
7. The control method according to claim 6, wherein each battery pack includes a plurality of unit cells connected in series; The in-group active equalization circuit comprises a plurality of in-group active equalization units, and one in-group active equalization unit is connected between two adjacent single batteries in each battery group; The inter-group active equalization circuit comprises at least two inter-group active equalization units, and one inter-group active equalization unit is connected between the positive electrode and the negative electrode of each battery group; the passive equalization circuit comprises a plurality of passive equalization units, and one passive equalization unit is connected between the positive electrode and the negative electrode of each single battery.
8. The control method according to claim 7, wherein, The first equalization data comprise an equalization direction of each intra-group active equalization unit, an equalization duty ratio of a plurality of intra-group active equalization units corresponding to the same battery group in each equalization period, a maximum equalization time of a plurality of intra-group active equalization units corresponding to the same battery group, and an opening time of each inter-group active equalization unit; the second equalization data includes an on time of each passive equalization unit.
9. The control method according to claim 8, wherein an equalization on period and an equalization off period are provided in each equalization period, wherein data update of the active equalization algorithm or the passive equalization algorithm is provided in the equalization off period.
10. A battery equalization control system for performing the battery equalization control method of any of claims 1-9 to control an active equalization circuit and a passive equalization circuit to equalize at least two battery packs in the battery equalization system.

Description

Battery equalization control system and control method Technical Field The invention relates to the technical field of battery equalization, in particular to a battery equalization control system and a battery equalization control method. Background The lithium battery comprises three types of lithium battery cells, a lithium battery pack and a lithium battery pack 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 active equalization scheme has high efficiency, but is complex in circuit and has serious oscillation, while the passive equalization scheme has low efficiency, although the circuit is simple. In addition, neither the active equalization scheme nor the passive equalization scheme has an effective failure handling approach. Therefore, a new battery equalization control system and control method have been proposed to solve the above-mentioned problems. Disclosure of Invention In view of the above problems, an object of the present invention is to provide a battery equalization control system and a control method, so as to reduce the system oscillation problem caused by the large active equalization current. According to one aspect of the invention, a battery balance control method is provided, and is used for controlling an active balance circuit and a passive balance circuit to balance at least two battery packs in a battery balance system, wherein the battery balance control method comprises the steps of obtaining a single cell voltage and/or a single cell residual capacity of each single cell in the at least two battery packs, selecting an active balance algorithm or a passive balance algorithm according to a difference value between a maximum single cell residual capacity and a minimum single cell residual capacity of each single cell in each battery pack, selecting the active balance algorithm to execute when the difference value corresponding to any battery pack is larger than a first threshold value, and selecting the passive balance algorithm to execute when the difference value corresponding to all battery packs is smaller than or equal to the first threshold value, wherein the active balance algorithm comprises an active balance algorithm based on the residual capacity and/or an active balance algorithm based on voltage. Optionally, the control method further comprises judging whether the active equalization circuit and the passive equalization circuit have faults, executing a passive equalization algorithm according to the acquired single voltage and/or single residual electric quantity when the active equalization circuit has faults, and executing t