A battery pack performance measurement method and energy storage system

Abstract

The present invention provides a performance measurement method for a battery pack and an energy storage system. The battery pack includes a plurality of battery modules, and the battery module includes a plurality of battery cells, wherein the performance measurement method for the battery pack includes: obtaining preset performance parameters of all battery cells in each battery module, the preset performance parameters at least including the voltage and health status of the battery cells, and the health status is calculated based on the working environment temperature, historical charge and discharge depth, and historical charge and discharge rate of the battery cells; obtaining a health score for each battery cell based on the preset performance parameters; and obtaining a performance score for the battery module based on the health scores of all battery cells in the battery module. This allows management personnel to roughly understand the status of each battery module through the performance score of the battery module, and then allows management personnel to determine the number of battery modules that need to be replaced in one replacement operation, and replace all battery modules with poor performance at one time, thereby helping to reduce the replacement frequency of the battery modules.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a battery pack performance measurement method and an energy storage system. Background Art

[0002] Energy storage systems, an integral part of the green power industry, store and redistribute electricity generated by renewable energy, thereby optimizing the allocation of power resources. The basic building block of an energy storage system is the battery pack, each of which is divided into multiple battery modules, and each battery module contains multiple battery cells. During the operation of an energy storage system, the performance of each battery cell may decline to varying degrees due to various factors. Poor performance of a single battery cell can also severely impact the overall performance of the battery module in which it resides, and ultimately, the overall performance of the battery pack.

[0003] Therefore, when a battery module experiences poor performance, the corresponding battery module must be replaced promptly. Currently, this is typically determined by reporting the highest and lowest cell voltages in the battery pack, and the battery module with the lowest cell voltage is replaced. However, this maintenance approach overly simplifies the determination of which battery modules require replacement, making it easy for some poorly performing battery modules to be left unreplaced, leading to excessively frequent battery module replacements. Summary of the Invention

[0004] An object of the present invention is to provide a battery pack performance measurement method and an energy storage system that can solve any of the above problems.

[0005] In particular, the present invention provides a method for measuring the performance of a battery pack, wherein the battery pack includes a plurality of battery modules, and the battery modules include a plurality of battery cells, wherein the method for measuring the performance of the battery pack includes:

[0006] Obtaining preset performance parameters of all battery cells in each of the battery modules, the preset performance parameters including at least the voltage and health status of the battery cells, the health status being calculated based on the operating environment temperature, historical charge and discharge depth, and historical charge and discharge rate of the battery cells;

[0007] Obtaining a health score for each battery cell based on the preset performance parameters;

[0008] A performance score of the battery module is obtained according to the health scores of all battery cells in the battery module.

[0009] Optionally, the step of obtaining the performance score of the battery module according to the health scores of all battery cells in the battery module includes:

[0010] Obtaining a plurality of different criterion parameters according to the health scores of all battery cells in the battery module;

[0011] The performance score of the battery module is obtained by summing the products of all the criterion parameters and their corresponding weight coefficients.

[0012] Optionally, the step of obtaining a plurality of different criterion parameters according to the health scores of all battery cells in the battery module includes:

[0013] averaging the health scores of all cells to obtain an average state criterion parameter;

[0014] Calculating the standard deviation of the health scores of all battery cells to obtain a consistency criterion parameter;

[0015] The health scores of all cells are minimized to obtain the worst condition criterion parameter.

[0016] Optionally, the weight coefficient corresponding to the worst state criterion parameter is greater than the weight coefficient corresponding to the average state criterion parameter, and the weight coefficient corresponding to the average state criterion parameter is greater than the weight coefficient corresponding to the consistency criterion parameter.

[0017] Optionally, the step of obtaining a health score for each battery cell according to the preset performance parameters includes:

[0018] A pre-built support vector machine model is used to obtain a health score for each battery cell based on the preset performance parameters.

[0019] Optionally, the preset performance parameters also include the initial capacity and life of the battery cell.

[0020] Optionally, after the step of obtaining the performance score of the battery module according to the health scores of all the battery cells in the battery module, the step further includes:

[0021] If it is detected that the performance score of the battery module is less than a preset value, a warning message is output, where the warning message includes the performance score of the battery module and a preset number.

[0022] Optionally, after the step of obtaining the preset performance parameters of all the battery cells in each of the battery modules, the following steps are included:

[0023] If it is detected that the battery module has a cell with a voltage lower than a preset voltage threshold, a preset number of the battery module is output.

[0024] Optionally, after the step of obtaining the performance score of the battery module according to the health scores of all the battery cells in the battery module, the step further includes:

[0025] If it is detected that the difference between the highest performance score and the lowest performance score in the battery pack is greater than a preset threshold, the performance scores and preset numbers of the battery modules corresponding to the highest performance score and the lowest performance score are output.

[0026] In another aspect of the present invention, there is also provided an energy storage system, comprising:

[0027] at least one battery pack; and

[0028] A controller includes a memory and a processor, wherein the memory stores a machine executable program, and when the machine executable program is executed by the processor, the performance measurement method of the battery pack according to any one of the above items is implemented.

[0029] The performance measurement method of the battery pack of the present invention obtains preset performance parameters of all battery cells in each battery module, the preset performance parameters include at least the voltage of the battery cell, obtains the health score of each battery cell according to the preset performance parameters, and obtains the performance score of the battery module according to the health score of all battery cells in the battery module, so that the performance of each battery module can be monitored and displayed in the form of a performance score, so that management personnel can roughly understand the status of each battery module through the performance score of the battery module, and then it is convenient for management personnel to determine the number of battery modules that need to be replaced in a replacement work, and replace all battery modules with poor performance at one time, which helps to reduce the replacement frequency of battery modules and reduce the workload of management personnel.

[0030] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Hereinafter, some specific embodiments of the present invention will be described in detail in an illustrative and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0032] Figure 1 is a schematic block diagram of a battery pack according to one embodiment of the present invention;

[0033] Figure 2 is a schematic block diagram of an energy storage system according to one embodiment of the present invention;

[0034] Figure 3 is a schematic flow chart of a method for measuring performance of a battery pack according to one embodiment of the present invention;

[0035] Figure 4is a schematic flow chart of the steps of obtaining a performance score of a battery module in a performance measurement method of a battery pack according to an embodiment of the present invention;

[0036] Figure 5 is a schematic flow chart of a method for measuring performance of a battery pack according to another embodiment of the present invention;

[0037] Figure 6 is a schematic flow chart of a method for measuring performance of a battery pack according to yet another embodiment of the present invention;

[0038] Figure 7 is a partial schematic flow chart of a method for measuring performance of a battery pack according to yet another embodiment of the present invention. DETAILED DESCRIPTION

[0039] It should be understood by those skilled in the art that the embodiments described below are only some embodiments of the present invention, rather than all embodiments of the present invention, and that these embodiments are intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present invention.

[0040] It should be noted that the logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or used in combination with these instruction execution systems, devices or apparatuses.

[0041] The flowchart provided in this embodiment is not intended to indicate that the operations of the method will be performed in any particular order, or that all operations of the method are included in all every case. In addition, the method may include additional operations. Within the scope of the technical ideas provided by the method of this embodiment, additional changes can be made to the above method.

[0042] like Figure 1 and Figure 2 As shown, in one embodiment, the battery pack 100 includes a plurality of battery modules 110, and the battery module 110 includes a plurality of battery cells 120. Specifically, the plurality of battery cells 120 are packaged into a battery module 110, and then the plurality of battery modules 110 together form the battery pack 100.

[0043] Furthermore, the energy storage system 10 includes multiple battery packs 100 and a controller 200. The controller 200 includes a memory and a processor. The memory stores a machine-executable program that, when executed by the processor, implements a battery pack performance measurement method according to any of the following embodiments. The controller 200 can be a battery management system (BMS) or an energy management system (EMS).

[0044] like Figure 3 As shown, in one embodiment, the performance measurement method of a battery pack generally includes:

[0045] Step S301: Obtain the preset performance parameters of all cells in each battery module. The preset performance parameters include the cell voltage and health status. The health status is the ratio of the cell's actual capacity to its initial capacity and is calculated based on the cell's operating environment temperature, historical charge and discharge depth, and historical charge and discharge rate. Specifically, the controller obtains the preset performance parameters of all cells in the battery module, which in this embodiment are the cell voltage and health status. The health status is calculated using the following formula:

[0046] ;

[0047] ;

[0048] Among them, the SOH result value plus the percentage sign is the health status of the battery cell, ɑ and b are fitting coefficients, which are obtained by fitting the battery cell experimental data to describe the battery capacity attenuation law, N is the cumulative degree of health loss of the battery cell, n is the number of charge and discharge records in the historical working conditions, and DOD ɑct The discharge depth under actual working conditions, that is, the discharge depth in historical records, DOD ref is the discharge depth under standard working conditions, usually taken as 100%, k DOD is the discharge depth stress factor index, greater than 1, C ɑct is the discharge rate under actual working conditions, C ref is the discharge rate under standard working conditions, usually 0.5C or 1C, k C is the rate stress factor index, greater than 1, e is a natural constant, k t is the temperature stress factor coefficient, which is less than 0, T ɑct is the working environment temperature under actual working conditions, T ref The working environment temperature under standard working conditions is usually 25 degrees Celsius.

[0049] By calculating the battery cell's health status based on the battery cell's operating environment temperature, historical charge and discharge depth, and historical charge and discharge rate, the battery cell's health status is made more accurate, which helps to more accurately determine the battery cell's health score.

[0050] Step S302: Obtain a health score for each battery cell based on preset performance parameters. Specifically, in some embodiments, this step includes using a pre-built support vector machine model to obtain a health score for each battery cell based on preset performance parameters. Specifically, the support vector machine model can use a Gaussian kernel function to classify nonlinear features and use a soft margin objective function:

[0051]

[0052] Transformed into a dual problem by Lagrange multiplier method:

[0053]

[0054] Get the final optimized function:

[0055]

[0056] In addition, model parameters can be optimized through cross-validation:

[0057]

[0058] It should be noted that how to construct a support vector machine model is well known to those skilled in the art, that is, the above formula is well known to those skilled in the art, and therefore, the meaning of the parameters in the formula is not further elaborated. In addition, using a support vector machine model to obtain a set health score based on the battery cell input parameters is well known to those skilled in the art and is not further elaborated here.

[0059] The health score can be a percentage score, or it can be set to three states: excellent, good, and poor, corresponding to 3 points, 2 points, and 1 point respectively.

[0060] Step S303 , obtaining a performance score of the battery module according to the health scores of all the battery cells in the battery module.

[0061] Reference Figure 4 Specifically, this step includes:

[0062] Step S401: derive multiple different criteria parameters based on the health scores of all cells in the battery module. In some embodiments, this step obtains three criteria parameters: specifically, the average health score of all cells is calculated to obtain an average condition criterion parameter, the standard deviation of the health scores of all cells is calculated to obtain a consistency criterion parameter, and the minimum health score of all cells is calculated to obtain a worst condition criterion parameter.

[0063] Step S402: sum the products of all criterion parameters and their corresponding weight coefficients to obtain the performance score of the battery module. Specifically, in the case of three criterion parameters, the performance score of the battery module is obtained using the following formula:

[0064] S B =C1ω1+C2ω2+C3ω3;

[0065] Among them, S B is the performance score of the battery module, C1 is the average state criterion parameter, C2 is the consistency criterion parameter, C3 is the worst state criterion parameter, ω1 is the weight coefficient of the average state criterion parameter, ω2 is the weight coefficient of the consistency criterion parameter, and ω3 is the weight coefficient of the worst state criterion parameter.

[0066] Furthermore, the performance score of the battery module was obtained using the AHP (Analytic Hierarchy Process) scoring method. Specifically, the importance of the three criterion parameters was evaluated. The importance of the three criterion parameters was ranked from high to low as the worst state criterion parameter, the average state criterion parameter, and the consistency criterion parameter. The weight coefficients obtained were ranked from large to small as the worst state criterion parameter weight coefficient, the average state criterion parameter weight coefficient, and the consistency criterion parameter weight coefficient. Specifically, the worst state criterion parameter weight coefficient was 0.7, the average state criterion parameter weight coefficient was 0.23, and the consistency criterion parameter weight coefficient was 0.07.

[0067] By averaging the health scores of all battery cells to obtain the average state criterion parameter, calculating the standard deviation of the health scores of all battery cells to obtain the consistency criterion parameter, and taking the minimum value of the health scores of all battery cells to obtain the worst state criterion parameter, the accurate measurement parameters involved in the performance score can reflect the overall performance of the battery module, the differences within the group, and the worst battery cell that causes the "water bucket effect", thereby comprehensively integrating multiple dimensions to obtain the performance score of the battery module, making the performance score more accurate.

[0068] In addition, by setting the importance of the three criterion parameters from high to low as the worst state criterion parameter, the average state criterion parameter, and the consistency criterion parameter, the weight coefficient corresponding to the worst state criterion parameter is greater than the weight coefficient corresponding to the average state criterion parameter, and the weight coefficient corresponding to the average state criterion parameter is greater than the weight coefficient corresponding to the consistency criterion parameter. Because the adverse impact of the wooden barrel effect on the battery module is the most serious, the weight coefficient corresponding to the worst state criterion parameter is set to the maximum, which is more conducive to finding the battery module with serious wooden barrel effect.

[0069] In the solution of this embodiment, by obtaining the preset performance parameters of all battery cells in each battery module, the preset performance parameters include at least the voltage of the battery cell, and obtaining the health score of each battery cell according to the preset performance parameters, and obtaining the performance score of the battery module according to the health score of all battery cells in the battery module, the performance of each battery module can be monitored and displayed in the form of a performance score, so that the management personnel can roughly understand the status of each battery module through the performance score of the battery module, and then it is convenient for the management personnel to determine the number of battery modules that need to be replaced in a replacement work, and replace all battery modules with poor performance at one time, which helps to reduce the replacement frequency of battery modules, improve the maintenance efficiency of battery packs, and reduce the workload of management personnel.

[0070] It should be noted that in some embodiments, the preset performance parameters may also include the initial capacity and lifespan of the battery cell, where the lifespan is the number of cycles of the battery cell. By obtaining a variety of performance parameters to obtain the health score of the battery cell, the health score is made more accurate.

[0071] like Figure 5 As shown, in one embodiment, the performance measurement method of a battery pack generally includes:

[0072] Step S501 , obtaining preset performance parameters of all battery cells in each battery module, where the preset performance parameters include the voltage of the battery cells.

[0073] Step S502: Obtain a health score for each battery cell according to preset performance parameters.

[0074] Step S503 , obtaining a performance score of the battery module according to the health scores of all the battery cells in the battery module.

[0075] In step S504, if the battery module's performance score is detected to be less than a preset value, a warning message is output. The warning message includes the battery module's performance score and a preset number. Specifically, when a battery module's performance score is detected to be less than a preset value, a warning message is directly output, for example, to a management system, allowing management personnel to receive notification from the management system via a computer or mobile device. This facilitates timely notification of battery modules with poor performance and allows for timely replacement of the battery modules.

[0076] It should be noted that, in this embodiment, for steps not described in detail, refer to the above description.

[0077] like Figure 6 As shown, in one embodiment, the performance measurement method of a battery pack generally includes:

[0078] Step S601 , obtaining preset performance parameters of all battery cells in each battery module, where the preset performance parameters include the voltage of the battery cells.

[0079] Step S602: Obtain a health score for each battery cell based on preset performance parameters.

[0080] Step S603 , obtaining a performance score of the battery module according to the health scores of all the battery cells in the battery module.

[0081] In step S604, if the difference between the highest and lowest performance scores in the battery pack is detected to be greater than a preset threshold, the performance scores and preset numbers of the battery modules corresponding to the highest and lowest performance scores are output. Specifically, after obtaining the performance scores of each battery module, if the difference between the highest and lowest performance scores is greater than a preset threshold, the performance scores and preset numbers of the battery modules corresponding to the highest and lowest performance scores are output. This facilitates management personnel in determining whether battery modules need to be replaced to avoid excessively unbalanced operating conditions in the battery pack, thereby ensuring the normal operation of the battery pack.

[0082] It should be noted that, in this embodiment, for steps not described in detail, refer to the above description.

[0083] like Figure 7 As shown, in one embodiment, the performance measurement method of a battery pack generally includes:

[0084] Step S701 , obtaining preset performance parameters of all battery cells in each battery module, where the preset performance parameters include the voltage of the battery cells.

[0085] Step S702: If a cell in the battery module is detected to have a voltage less than a preset voltage threshold, the preset number of the battery module is output. Specifically, if a single cell in the battery module has an exceptionally low voltage, while the voltages of the remaining cells are normal, a high performance score may be achieved. Therefore, if a cell in the battery module is detected to have a voltage less than the preset voltage threshold, the preset number of the battery module is output to avoid missing a battery module with a single cell within the module that has an excessively low voltage.

[0086] At this point, those skilled in the art will recognize that, although a number of exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A method for measuring the performance of a battery pack, wherein the battery pack comprises a plurality of battery modules, each of which comprises a plurality of battery cells, characterized in that: The battery pack performance measurement method includes: Obtaining preset performance parameters of all battery cells in each of the battery modules, the preset performance parameters including at least the voltage and health status of the battery cells, the health status being calculated based on the operating environment temperature, historical charge and discharge depth, and historical charge and discharge rate of the battery cells; Obtaining a health score for each battery cell based on the preset performance parameters; Obtaining a performance score of the battery module according to the health scores of all the battery cells in the battery module; the step of obtaining the performance score of the battery module according to the health scores of all the battery cells in the battery module comprises: Obtaining a plurality of different criterion parameters according to the health scores of all battery cells in the battery module; The steps of summing the products of all the criterion parameters and their corresponding weight coefficients to obtain the performance score of the battery module; and obtaining a plurality of different criterion parameters according to the health scores of all the cells in the battery module include: averaging the health scores of all cells to obtain an average state criterion parameter; Calculating the standard deviation of the health scores of all battery cells to obtain a consistency criterion parameter; Taking the minimum value of the health score of all cells to obtain the worst state criterion parameter; The weight coefficient corresponding to the worst state criterion parameter is greater than the weight coefficient corresponding to the average state criterion parameter, and the weight coefficient corresponding to the average state criterion parameter is greater than the weight coefficient corresponding to the consistency criterion parameter; After the step of obtaining the performance score of the battery module according to the health scores of all the battery cells in the battery module, the method further comprises: If it is detected that the performance score of the battery module is less than a preset value, outputting a warning message, the warning message including the performance score of the battery module and a preset number; If it is detected that the difference between the highest performance score and the lowest performance score in the battery pack is greater than a preset threshold, the performance scores and preset numbers of the battery modules corresponding to the highest performance score and the lowest performance score are output.

2. The battery pack performance measurement method according to claim 1, characterized in that: The step of obtaining a health score for each battery cell according to the preset performance parameters includes: A pre-built support vector machine model is used to obtain a health score for each battery cell based on the preset performance parameters.

3. The battery pack performance measurement method according to claim 1, characterized in that: The preset performance parameters also include the initial capacity and life of the battery cell.

4. The battery pack performance measurement method according to claim 1, characterized in that: After the step of obtaining the preset performance parameters of all the cells in each of the battery modules, the method further comprises: If it is detected that the battery module has a cell with a voltage lower than a preset voltage threshold, a preset number of the battery module is output.

5. An energy storage system, characterized in that: include: at least one battery pack; and A controller comprising a memory and a processor, wherein the memory stores a machine executable program, and when the machine executable program is executed by the processor, the performance measurement method of the battery pack according to any one of claims 1 to 4 is implemented.

Images