CN104935057A - A method and system for equalizing a lithium-ion battery pack - Google Patents

Abstract

The present invention discloses an equalization method and an equalization system for a lithium ion battery pack. The equalization method comprises the steps of: performing equalization for states of adjacent single-battery units in the lithium ion battery pack and acquiring voltage information of the single-battery unit by a first-stage equalization module; performing equalization for states of adjacent two-battery units by a second-stage equalization module; performing equalization for states of adjacent four-battery units by a third-stage equalization module; and obtaining the voltage information and generating an equalization control instruction by a processor, so as to control the first-stage equalization module, the second-stage equalization module and the third-stage equalization module to perform corresponding state equalization operation. According to the above technical scheme, the equalization system consisting of the first-stage equalization module, the second-stage equalization module, the third-stage equalization module and the processor is simple in structure and low in cost, and equalization mechanism of the whole equalization system can be conveniently and quickly changed through modification of an equalization algorithm in the processor, thereby achieving the purpose of simply and conveniently controlling work states of the equalization modules.

Description

A method and system for equalizing a lithium-ion battery pack

technical field

The invention relates to the technical field of battery balancing, in particular to a method and system for balancing lithium-ion battery packs.

Background technique

Today, lithium-ion battery packs formed by connecting battery cells in series are widely used in electric vehicles as an energy source for electric vehicles.

In the process of using lithium-ion battery packs, due to the subtle differences in the parameters of each battery unit at the factory, as well as different internal resistances and different ambient temperatures during use, the charging and discharging rates of different battery units may be affected. different. When they are connected in series to form a battery pack and charged, it is possible that some battery cells are fully charged in advance during charging, and some battery cells are fully discharged in advance when discharging. Therefore, lithium-ion battery packs must have a balancing system to balance the above-mentioned unbalanced conditions.

In the prior art, an active equalization scheme is usually used to balance the battery pack. The active equalization scheme has a large equalization current and less energy loss, but the structure of the entire equalization system is relatively complicated, and the cost is also high, and it is difficult to realize the equalization of the equalization module. The current working state is controlled.

Contents of the invention

In view of this, the present invention provides a lithium-ion battery pack equalization method and system to achieve the purpose of simple structure and low cost of the equalization system, and simple and quick control operation of the working state of the equalization module.

In order to solve the above technical problems, the present invention provides a lithium-ion battery pack equalization method, which is applied to a lithium-ion battery pack equalization system. The system includes a first-level equalization module, a second-level equalization module, a third-level equalization module and a processor. The method include:

The first-level equalization module balances the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collects the voltage information of the single-cell battery cells;

The secondary balance module balances the state between two adjacent battery cells in the lithium-ion battery pack;

The three-level equalization module equalizes the state between four adjacent battery cells in the lithium-ion battery pack;

The processor acquires the voltage information, and generates an equalization control instruction according to the voltage information, so as to control the first-level equalization module, the second-level equalization module, and the third-level equalization module to perform corresponding state equalization operations;

Wherein, the lithium-ion battery pack includes at least one battery unit, the two battery units are adjacent single-cell battery units balanced by the first-level balancing module, and the four battery units are the second-level balancing module Balanced adjacent two battery cells.

In the above method, preferably, the RS485 communication protocol is used to obtain the voltage information collected by the primary equalization module.

In the above method, preferably, it also includes:

An overvoltage protection operation is performed on a single battery cell in the lithium-ion battery pack.

In the above method, preferably, it also includes:

When an abnormality occurs in the process of obtaining the voltage information collected by the primary equalization module, an emergency alarm is activated.

In the above method, preferably, it also includes:

When an abnormality occurs in the process of obtaining the voltage information collected by the first-level equalization module, the first-level equalization module, the second-level equalization module, and the third-level equalization module enter an autonomous equalization mode.

The present invention also provides a lithium-ion battery pack balancing system, comprising:

A first-level equalization module, used to balance the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collect voltage information of the single-cell battery cells;

A secondary balancing module, used to balance the state between two adjacent battery cells in the lithium-ion battery pack;

A three-stage balancing module, used to balance the states between four adjacent battery cells in the lithium-ion battery pack;

A processor, configured to obtain the voltage information collected by the first-level equalization module, and generate an equalization control instruction according to the voltage information, so as to control the first-level equalization module, the second-level equalization module, and the third-level equalization module to execute corresponding states balancing operation;

Wherein, the lithium-ion battery pack includes at least one battery unit, and the two battery units are adjacent single-cell battery units balanced by the first-level balancing module; the four battery units are the second-level balancing module Balanced adjacent two battery cells.

In the above system, preferably, the primary equalization module further includes:

The overvoltage protection sub-module is used to perform an overvoltage protection operation on a single battery unit in the lithium-ion battery pack.

In the above system, preferably, it also includes:

An alarm module, configured to initiate an emergency alarm when an abnormality occurs in the process of obtaining the voltage information collected by the first-level equalization module.

In the lithium-ion battery pack balancing method and system provided by the present invention above, the first-level equalization module balances the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collects voltage information of the single-cell battery cells; The second-level balance module balances the state between two adjacent battery cells in the lithium-ion battery pack; the third-level balance module balances the state between four adjacent battery cells in the lithium-ion battery pack; the processor obtains the voltage information, and generate an equalization control instruction according to the voltage information, so as to control the first-level equalization module, the second-level equalization module, and the third-level equalization module to perform corresponding state equalization operations. Since there is a preset equalization algorithm in the processor, this equalization algorithm determines the equalization mechanism of the entire system. Therefore, by modifying the equalization algorithm in the processor, the equalization mechanism of the entire equalization system can be changed conveniently and quickly, thereby realizing a simple The purpose of conveniently controlling the working status of each equalization module. At the same time, the equalization system composed of the above-mentioned first-level equalization module, second-level equalization module, third-level equalization module and processor has a simple structure and low cost. With the corresponding number of equalization modules, the modification of the scheme can be completed quickly.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is a flow chart of a lithium-ion battery pack equalization method provided by an embodiment of the present invention;

Fig. 2 is a structural block diagram schematic diagram of a lithium-ion battery pack balancing system provided by an embodiment of the present invention;

3 is a schematic diagram of another structural block diagram of a lithium-ion battery pack equalization system provided by an embodiment of the present invention;

FIG. 4 is a schematic diagram of another structural block diagram of a balancing system for a lithium-ion battery pack provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The core of the present invention is to provide a lithium-ion battery pack equalization method and system, so as to achieve the purpose of simple structure and low cost of the equalization system, and simple and quick control and operation of the working state of the equalization module.

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Please refer to Fig. 1, Fig. 2 and Fig. 3, Fig. 1 shows a flow chart of a lithium-ion battery pack equalization method provided by an embodiment of the present invention, and Fig. 2 shows a lithium-ion battery provided by an embodiment of the present invention A schematic structural block diagram of a group balancing system, and FIG. 3 shows another structural block diagram of a lithium-ion battery group balancing system provided by an embodiment of the present invention. In the figure, BAT1, BAT2, ... are all single-cell battery units;

The lithium-ion battery pack equalization method of the present invention is applied to a lithium-ion battery pack equalization system 100, and the system 100 includes a first-level equalization module 101, a second-level equalization module 102, a third-level equalization module 103, and a processor 104. The method may specifically include Follow the steps below:

Step S100, the first-level balancing module 101 balances the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collects voltage information of the single-cell battery cells;

Step S101, the secondary equalization module 102 equalizes the state between two adjacent battery cells in the lithium-ion battery pack;

Step S102, the three-level equalization module 103 equalizes the state between four adjacent battery cells in the lithium-ion battery pack;

Step S103, the processor 104 obtains the voltage information, and generates an equalization control instruction according to the voltage information, so as to control the primary equalization module 101, the secondary equalization module 102, and the third-level equalization module 103 to perform corresponding state equalization operations;

In step S103, specifically, according to actual needs, the processor 104 may issue a compulsory equalization control instruction to each equalization module mentioned above, so as to forcibly control each equalization module to perform a corresponding state equalization operation;

Further, regarding the manner in which the processor 104 obtains the voltage information, it may use the RS485 communication protocol to obtain the voltage information collected by the primary equalization module 101 . In practical applications, the processor 104 may be a battery management system (Battery Management System, BMS for short), and the BMS is taken as an example below for description;

Wherein, the lithium-ion battery pack includes at least one battery unit, two battery units are adjacent single-cell battery units balanced by the primary balancing module 101, and four battery cells are adjacent two battery cells balanced by the secondary balancing module 102 battery unit.

Specifically, an example is given in conjunction with the accompanying drawings:

The primary equalization module 101 equalizes the state between adjacent BAT7 and BAT8;

The secondary equalization module 102 balances the state between two battery units I and two battery units II, wherein, the two battery units I are composed of BAT7 and BAT8, and the two battery units II are composed of BAT5 and BAT6, where The two battery units I and the two battery units II are two battery units;

The three-stage equalization module 103 balances the state between four battery units ① and four battery units ②, wherein the four battery units ① are composed of two adjacent battery units I and two battery units II, and four battery units The battery unit ② is composed of two adjacent battery units III and two battery units IV, the two battery units III are composed of BAT3 and BAT4, and the two battery units IV are composed of IBAT1 and BAT2.

The lithium-ion battery pack equalization method disclosed in this embodiment above has a preset equalization algorithm in the BMS, and this equalization algorithm determines the equalization mechanism of the entire system. Therefore, it can be convenient and quick by modifying the equalization algorithm in the processor 104. The equalization mechanism of the entire equalization system can be changed in a timely manner, that is to say, the equalization scheme upgrade can be completed only by upgrading the BMS software, so as to achieve the purpose of simply and conveniently controlling the working status of each equalization module. Simultaneously, the equalization system that is made up of above-mentioned one-level balance module 101, two-level balance module 102, three-level balance module 103 and processor 104 is simple in structure, and cost is low, when the number of battery cells in the lithium-ion battery pack needs to increase or decrease, It is only necessary to increase or decrease the number of corresponding equalization modules, and the modification of the scheme can be completed quickly.

In addition, in the lithium-ion battery pack equalization system applied by the lithium-ion battery pack equalization method, energy is transferred between batteries, reducing energy loss.

Referring to Fig. 3 and Fig. 4, Fig. 4 shows a schematic block diagram of another structural block diagram of a lithium-ion battery pack equalization system provided by an embodiment of the present invention. In order to improve the reliability of the system, the primary equalization module 101 also includes an overvoltage protection Based on this, the sub-module can also use the over-voltage protection sub-module to perform an over-voltage protection operation on a single battery cell in the lithium-ion battery pack. In this embodiment, the voltage sampling and overvoltage protection preferably only need to be implemented in the first-level equalization module 101, which uploads voltage information to the BMS through 485 communication, and the BMS issues equalization control commands based on the overall voltage information of the battery pack to force control The equalization states of the first, second and third level equalization modules 103 .

Specifically, the control chip OR-ing FET Controller and the external MOS transistor together constitute an overvoltage protection module;

In order to further improve the reliability of the system, in the embodiment of the present invention, the equalization system 100 also has an independent emergency alarm channel. When the process of obtaining the voltage information collected by the primary equalization module 101 is abnormal, an emergency alarm is activated. At this time, in order to ensure the normal operation of each equalization module, the first level equalization module 101, the second level equalization module 102 and the third level equalization module 103 enter the autonomous equalization mode, and are no longer uniformly controlled by the BMS.

In summary, it can be seen that the embodiment of the present invention realizes the integrated design of sampling, communication, protection and control balance, and integrates various functions such as voltage sampling, overvoltage protection, working state control, battery balancing, and data communication into one balancing module, and A multi-level balancing structure is adopted, wherein the first-level balancing module 101 is responsible for battery balancing between single cells, the second-level balancing module 102 is responsible for battery balancing between two cells and between two cells, and the third-level balancing module 103 is responsible for four cells and between four cells. battery balancing. Furthermore, multi-level independent equalization units are used to build the entire equalization system, and the number of equalization units can be increased or decreased according to needs; a sampling function is added to the first-level equalization unit, and after the sampling data is transmitted to the BMS, the working status of the entire equalization system is controlled; Energy is transferred between batteries, reducing energy loss.

Corresponding to the lithium-ion battery pack equalization method provided by the above-mentioned embodiment of the present invention, the embodiment of the present invention also provides a lithium-ion battery pack equalization system. Referring to FIG. 2, the system 100 may include the following contents:

The first-level equalization module 101 is used to balance the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collect voltage information of the single-cell battery cells;

The secondary balancing module 102 is used to balance the state between two adjacent battery cells in the lithium-ion battery pack;

The three-level balancing module 103 is used to balance the states between the adjacent four battery cells in the lithium-ion battery pack;

The processor 104 is configured to obtain the voltage information collected by the primary equalization module 101, and generate equalization control instructions according to the voltage information, so as to control the primary equalization module 101, the secondary equalization module 102, and the third-stage equalization module 103 to perform corresponding state equalization operate;

Wherein, the lithium-ion battery pack includes at least one battery unit, two battery units are adjacent single-cell battery units balanced by the first-level equalization module 101; four battery units are adjacent two-cell battery units balanced by the second-level equalization module 102 .

Preferably, the primary equalization module 101 may also include:

The overvoltage protection sub-module is used to perform an overvoltage protection operation on a single battery cell in a lithium-ion battery pack.

Preferably, the above equalization system 100 may also include:

The alarm module is configured to initiate an emergency alarm when the process of obtaining the voltage information collected by the primary equalization module 101 is abnormal.

It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the same and similar parts in each embodiment, refer to each other, that is, Can. As for the system embodiment, because it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, please refer to the part of the description of the method embodiment.

The method and system for equalizing a lithium-ion battery pack provided by the present invention have been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (8)

1. A lithium-ion battery pack equalization method is characterized in that it is applied to a lithium-ion battery pack equalization system, and the system includes a first-level equalization module, a second-level equalization module, a three-level equalization module and a processor, and the method includes: The first-level equalization module balances the state between adjacent single-cell battery units in the lithium-ion battery pack, and collects voltage information of the single-cell battery cells; The secondary equalization module equalizes the state between two adjacent battery cells in the lithium-ion battery pack; The three-stage equalization module equalizes the state between four adjacent battery cells in the lithium-ion battery pack; The processor acquires the voltage information, and generates an equalization control instruction according to the voltage information, so as to control the first-level equalization module, the second-level equalization module, and the third-level equalization module to perform corresponding state equalization operations; Wherein, the lithium-ion battery pack includes at least one battery unit, the two battery units are adjacent single-cell battery units balanced by the first-level balancing module, and the four battery units are the second-level balancing module Balanced adjacent two battery cells. 2. The method according to claim 1, characterized in that, the voltage information collected by the primary equalization module is obtained by using the RS485 communication protocol. 3. The method according to any one of claims 1 or 2, further comprising: An overvoltage protection operation is performed on a single battery cell in the lithium-ion battery pack. 4. The method of claim 3, further comprising: When an abnormality occurs in the process of obtaining the voltage information collected by the primary equalization module, an emergency alarm is activated. 5. The method of claim 4, further comprising: When an abnormality occurs in the process of obtaining the voltage information collected by the first-level equalization module, the first-level equalization module, the second-level equalization module, and the third-level equalization module enter an autonomous equalization mode. 6. A lithium-ion battery pack balancing system, characterized in that, comprising: A first-level equalization module, used to balance the state between adjacent single-cell battery cells in the lithium-ion battery pack, and collect voltage information of the single-cell battery cells; A secondary balancing module, used to balance the state between two adjacent battery cells in the lithium-ion battery pack; A three-stage balancing module, used to balance the states between four adjacent battery cells in the lithium-ion battery pack; A processor, configured to obtain the voltage information collected by the first-level equalization module, and generate an equalization control instruction according to the voltage information, so as to control the first-level equalization module, the second-level equalization module, and the third-level equalization module to execute corresponding states balancing operation; Wherein, the lithium-ion battery pack includes at least one battery unit, and the two battery units are adjacent single-cell battery units balanced by the first-level equalization module; the four battery units are the second-level equalization module Balanced adjacent two battery cells. 7. The system according to claim 6, wherein the first-level equalization module further comprises: The overvoltage protection sub-module is used to perform an overvoltage protection operation on a single battery unit in the lithium-ion battery pack. 8. The system of claim 7, further comprising: An alarm module, configured to initiate an emergency alarm when an abnormality occurs in the process of obtaining the voltage information collected by the first-level equalization module.