A method and device for estimating power battery life

Abstract

The present invention discloses a method and device for estimating the life of a power battery, comprising: obtaining the temperature of each power battery cell in a whole pack of power batteries; calculating the cell SOH value corresponding to each power battery cell based on the cell attenuation model according to the temperature; calculating the power of each power battery cell according to the temperature; calculating the initial whole pack SOH value of the whole pack of power batteries according to the cell SOH value and the power, and obtaining the ampere-hour value of each initial whole pack SOH value; calculating the corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value; performing parameter identification on the cell attenuation model according to the corrected whole pack SOH value and the ampere-hour value of each corrected whole pack SOH value, and generating a whole pack attenuation model; estimating the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model. The application of the present invention can improve the accuracy of the estimated whole pack SOH value of the whole pack of power batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a method and device for estimating the life of a power battery. Background Art

[0002] With the rapid development of new energy technologies, more and more fields have begun to use power batteries as energy storage devices for equipment. However, the performance of power batteries will gradually decline as the application time increases, resulting in a worse user experience. Therefore, it is necessary to accurately estimate the life of power batteries.

[0003] Most of the existing methods for estimating the life of power batteries are based on specific operating conditions and cannot reflect the state of the power battery itself, resulting in unsatisfactory estimation results. Summary of the invention

[0004] The present invention provides a method and device for estimating the life of a power battery, so as to overcome at least one technical problem existing in the prior art.

[0005] According to a first aspect of an embodiment of the present invention, a method for estimating the life of a power battery is provided, comprising: obtaining the temperature of each power battery cell in a whole pack of power batteries;

[0006] According to the temperature, based on a preset cell attenuation model, the cell SOH value corresponding to each power battery cell is calculated;

[0007] Calculating the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model;

[0008] Calculating the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity, and obtaining the first ampere-hour value corresponding to each initial whole pack SOH value;

[0009] Calculating a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value based on a preset correction formula, wherein one corrected whole pack SOH value corresponds to one first ampere-hour value;

[0010] According to the corrected whole-package SOH value and the first ampere-hour values ​​corresponding to each corrected whole-package SOH value, parameter identification is performed on the monomer attenuation model to generate a whole-package attenuation model;

[0011] Based on the whole pack attenuation model, an estimated whole pack SOH value of the whole pack of power batteries is estimated.

[0012] Optionally, the step of obtaining the temperature of each power battery cell in a whole pack of power batteries includes:

[0013] According to the current of each power battery cell in the whole pack of power batteries, the heat generation of each power battery cell is calculated based on the following formula;

[0014]

[0015] In the formula, q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i;

[0016] According to the heat generated by each power battery cell, the temperature of each power battery cell is calculated based on the following formula;

[0017]

[0018] In the formula, T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, A area is the heat exchange area between the battery cells in the module and the environment, ρ is the density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T amb is the ambient temperature, and q0 is the heat generated by each power battery cell.

[0019] Optionally, the step of calculating the SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model includes:

[0020] Acquire the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature;

[0021] According to the temperature and the second ampere-hour value, based on the following formula, calculating the capacity loss of each power battery cell at time i;

[0022]

[0023] In the formula, Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell;

[0024] According to the capacity loss of each power battery cell at time i, based on the following preset cell attenuation model, calculate the cell SOH value of each power battery cell;

[0025]

[0026] In the formula, SOH cell is the single cell SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

[0027] Optionally, the step of calculating an initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity includes:

[0028] According to the single cell SOH value and the power quantity, the capacity of the whole pack of power batteries is calculated based on the following formula;

[0029] C pack =min(SOC·C)+min((1-SOC)·C)

[0030] Among them, C pack is the capacity of the whole pack of power batteries, SOC is the power, and C is the cell capacity, wherein the cell capacity C is equal to the product of the corrected cell SOH value and the rated capacity of each power battery cell;

[0031] According to the capacity of the whole pack of power batteries, multiple initial whole pack SOH values ​​corresponding to the whole pack of power batteries are calculated based on the following formula;

[0032]

[0033] Among them, SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity C of each parallel power battery cell T sum.

[0034] Optionally, the step of calculating the corrected whole pack SOH value of the whole pack of power batteries based on the initial whole pack SOH value and the obtained measured whole pack SOH value based on a preset correction formula includes:

[0035] Obtaining a measured SOH value of the whole pack of power batteries obtained by actual measurement;

[0036] According to the initial whole pack SOH value and the measured whole pack SOH value, based on the following preset correction formula, a corrected whole pack SOH value of the whole pack of power batteries is calculated;

[0037]

[0038] In the formula, SOH k,mod is the corrected SOH value of the whole pack of power batteries at time k, Ah k is the accumulated ampere-hour data from the start time to time k, Ah is the total ampere-hour data from the start time to the correction time, where the start time is the previous correction time, SOH pack is the initial SOH value of the whole pack of power batteries at time k before correction, SOH act is a measured SOH value of the whole pack of power batteries, and error represents SOH act With SOH pack The error between .

[0039] Optionally, the step of performing parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​corresponding to each corrected whole package SOH value to generate the whole package attenuation model includes:

[0040] According to at least three of the corrected whole pack SOH values ​​and the first ampere-hour value corresponding to the at least three corrected whole pack SOH values, the capacity loss coefficient A, the activation energy Ea of battery cell decay and the preset parameter z in the single cell decay model are corrected to obtain the whole pack decay model.

[0041] Optionally, the step of estimating the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model includes:

[0042] Based on the following whole pack attenuation model, estimate the estimated whole pack SOH value of the whole pack of power batteries;

[0043]

[0044] In the formula, SOH bag is the estimated SOH value of the whole pack of power batteries, Q i is the capacity loss of the whole pack of power batteries at time i, i=1, 2, ..., n.

[0045] According to a second aspect of an embodiment of the present invention, there is provided a device for estimating the life of a power battery, comprising:

[0046] An acquisition module is used to acquire the temperature of each power battery cell in a whole pack of power batteries;

[0047] A first calculation module, configured to calculate the SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model;

[0048] A second calculation module, configured to calculate the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model;

[0049] A third calculation module is used to calculate the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity, and obtain the first ampere-hour value corresponding to each initial whole pack SOH value;

[0050] a fourth calculation module, configured to calculate a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value, based on a preset correction formula, wherein one corrected whole pack SOH value corresponds to one first ampere-hour value;

[0051] A generating module, configured to perform parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​respectively corresponding to each corrected whole package SOH value, so as to generate a whole package attenuation model;

[0052] An estimation module is used to estimate the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model.

[0053] Optionally, the acquisition module specifically includes:

[0054] A first calculation submodule, configured to calculate the heat generation of each power battery cell according to the current of each power battery cell in the whole pack of power batteries based on the following formula;

[0055]

[0056] In the formula, q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i;

[0057] A second calculation submodule, configured to calculate the temperature of each power battery cell according to the heat generated by each power battery cell based on the following formula;

[0058]

[0059] In the formula, T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, Aarea is the heat exchange area between the battery cells in the module and the environment, ρ is the density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T amb is the ambient temperature, and q0 is the heat generated by each power battery cell.

[0060] Optionally, the first calculation module specifically includes:

[0061] an acquisition submodule, used for acquiring the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature;

[0062] A third calculation submodule, configured to calculate the capacity loss of each power battery cell at time i according to the temperature and the second ampere-hour value based on the following formula;

[0063]

[0064] In the formula, Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell;

[0065] A fourth calculation submodule, configured to calculate the SOH value of each power battery cell according to the capacity loss of each power battery cell at time i and based on the following preset cell attenuation model;

[0066]

[0067] In the formula, SOH cell is the single cell SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

[0068] Optionally, the third computing module specifically includes:

[0069] A fifth calculation submodule, configured to calculate the capacity of the entire pack of power batteries according to the single cell SOH value and the power quantity based on the following formula;

[0070] C pack =min(SOC·C)+min((1-SOC)·C)

[0071] Among them, C packis the capacity of the whole pack of power batteries, SOC is the power, and C is the cell capacity, wherein the cell capacity C is equal to the product of the corrected cell SOH value and the rated capacity of each power battery cell;

[0072] A sixth calculation submodule, configured to calculate a plurality of initial whole pack SOH values ​​corresponding to the whole pack of power batteries according to the capacity of the whole pack of power batteries and based on the following formula;

[0073]

[0074] Among them, SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity C of each parallel power battery cell T sum.

[0075] Optionally, the fourth computing module specifically includes:

[0076] The second acquisition submodule is used to obtain the actual measured SOH value of the whole pack of power batteries obtained by actual measurement;

[0077] A seventh calculation submodule, configured to calculate a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the measured whole pack SOH value based on the following preset correction formula;

[0078]

[0079] In the formula, SOH k,mod is the corrected SOH value of the whole pack of power batteries at time k, Ah k is the accumulated ampere-hour data from the start time to time k, Ah is the total ampere-hour data from the start time to the correction time, where the start time is the previous correction time, SOH pack is the initial SOH value of the whole pack of power batteries at time k before correction, SOH act is a measured SOH value of the whole pack of power batteries, and error represents SOH act With SOH pack The error between .

[0080] Optionally, the generation module is specifically used to correct the capacity loss coefficient A, the activation energy Ea of battery cell decay and the preset parameter z in the single cell decay model according to at least three of the corrected whole pack SOH values ​​and the first ampere-hour value corresponding to the at least three corrected whole pack SOH values ​​to obtain the whole pack decay model.

[0081] Optionally, the estimation module is specifically used to estimate the estimated whole pack SOH value of the whole pack of power batteries based on the following whole pack attenuation model;

[0082]

[0083] In the formula, SOH bag is the estimated SOH value of the whole pack of power batteries, Q i is the capacity loss of the whole pack of power batteries at time i, i=1, 2, ..., n.

[0084] The innovative features of the embodiments of the present invention include:

[0085] 1. According to the temperature of each single power battery in the whole pack of power batteries, the real-time SOH value of the single power battery is calculated. In addition, the single power of the single power battery is calculated according to the temperature, so as to calculate the initial whole pack SOH value of the whole pack of power batteries based on the single power battery SOH value and power. Since the current temperature of the single power battery is taken into account in the calculation of the single power battery SOH value and the initial whole pack SOH value, the estimated whole pack SOH value estimated based on the initial whole pack SOH value is more accurate, which is one of the innovations of the embodiment of the present invention.

[0086] 2. According to a series of calculated initial whole package SOH values ​​and an actual whole package SOH value obtained by actual measurement, an error value is obtained, and then based on the error value, the calculated series of initial whole package SOH values ​​are corrected to obtain a corrected whole package SOH value; next, based on the corrected whole package SOH value and the first ampere-hour value corresponding to each corrected whole package SOH value, parameter identification is performed on the single cell attenuation model to generate a whole package attenuation model for estimating the estimated whole package SOH value of a whole package of power batteries, so that the estimated whole package SOH value calculated by the whole package attenuation model is closer and closer to the actual situation, which is one of the innovations of the embodiments of the present invention.

[0087] 3. The heat generated by the power battery cells is calculated by the current of each power battery cell in the whole pack of power batteries, and then the temperature of each power battery cell is calculated based on the heat generated by the battery cells. Since the temperature can reflect the state of the power battery itself, the calculated temperature is used to calculate the single cell SOH value and power. The single cell SOH value and power take into account the state of each power battery cell itself, improving the accuracy of the single cell SOH value and power is one of the innovative points of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0089] Figure 1 A schematic diagram of a processing flow of a method for estimating the life of a power battery according to the present invention;

[0090] Figure 2 Schematic diagram of the processing flow of step 100 in the present invention;

[0091] Figure 3 Schematic diagram of the processing flow of step 102 in the present invention;

[0092] Figure 4 is a schematic diagram of the processing flow of step 106 in the present invention;

[0093] Figure 5 Schematic diagram of the processing flow of step 108 in the present invention;

[0094] Figure 6 It is a schematic diagram of the structure of the device for estimating the life of a power battery of the present invention. DETAILED DESCRIPTION

[0095] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0096] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0097] The embodiment of the present invention discloses a method and device for estimating the life of a power battery, which are described in detail below.

[0098] The present invention proposes a method for estimating the life of a power battery, referring to Figure 1 , Figure 1FIG. 1 is a schematic diagram of a processing flow of a method for estimating the life of a power battery according to the present invention. Figure 1 As shown, the method for estimating the life of the power battery includes the following steps:

[0099] Step 100: obtaining the temperature of each power battery cell in a whole pack of power batteries.

[0100] In this step, the temperature of each power battery cell in the whole pack of power batteries can be obtained. The temperature can reflect the state of the power battery itself, so that the single cell SOH value and power can be calculated based on the temperature, so that the single cell SOH value and power can take into account the influence of the different temperatures of each power battery cell, thereby improving the accuracy of the single cell SOH value and power.

[0101] Optional, reference Figure 2 , Figure 2 is a schematic diagram of the processing flow of step 100 in the present invention, such as Figure 2 As shown, step 100 may specifically include the following sub-steps:

[0102] Sub-step 11, calculating the heat generated by each power battery cell according to the current of each power battery cell in the whole pack of power batteries and based on formula (1);

[0103]

[0104] In formula (1), q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i.

[0105] Specifically, according to the current and resistance value of the power battery cell, based on formula (1), the heat generation of each power battery cell is calculated, so that the temperature of each power battery cell is calculated based on the heat generation of the battery cell.

[0106] Sub-step 12, calculating the temperature of each power battery cell according to the heat generated by each power battery cell and based on formula (2);

[0107]

[0108] In formula (2), T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, A area is the heat exchange area between the battery cells in the module and the environment, ρ is the density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T ambis the ambient temperature, and q0 is the heat generated by each power battery cell.

[0109] Specifically, the heat generated by each power battery cell can be calculated according to formula (1), and the temperature of each power battery cell in the whole battery pack can be calculated based on formula (2). Then, through subsequent steps, the cell SOH value of each power battery cell can be calculated based on the temperature of each power battery cell.

[0110] Step 102 : Calculate the SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model.

[0111] In this step, the cell SOH value corresponding to each power battery cell in the whole pack of power batteries obtained in step 100 can be calculated based on a preset cell attenuation model, so as to calculate the initial whole pack SOH value of the whole pack of power batteries based on the cell SOH value.

[0112] Optional, reference Figure 3 , Figure 3 1 is a schematic diagram of the processing flow of step 102 in the present invention, and step 102 specifically includes:

[0113] Sub-step 21 : acquiring the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature.

[0114] Specifically, the temperature of each power battery cell in the whole battery pack may be obtained, and the ampere-hour value of each power battery cell at the temperature may be obtained. For ease of understanding, the ampere-hour value of each power battery cell at the temperature is recorded as the second ampere-hour value.

[0115] Sub-step 22, calculating the capacity loss of each power battery cell at time i according to the temperature and the second ampere-hour value based on formula (3);

[0116]

[0117] In formula (3), Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell.

[0118] Specifically, since sub-step 21 has obtained the temperature of each power battery cell and the second ampere-hour value, in this step, the capacity loss of each power battery cell at a certain moment (moment i) can be calculated based on formula (3), so as to calculate the cell SOH value of each power battery cell based on the capacity loss at a certain moment.

[0119] Sub-step 23, according to the capacity loss of each power battery cell at time i, based on the following preset cell attenuation model, calculating the cell SOH value of each power battery cell;

[0120]

[0121] In formula (4), SOH cell is the single cell SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

[0122] Specifically, according to the capacity loss of each power battery cell at a certain moment (moment i) calculated in sub-step 22, the capacity loss over a period of time is accumulated, and the cell SOH value of each power battery cell is calculated based on formula (4).

[0123] It can be understood that the calculated monomer SOH value is real-time.

[0124] Step 104 : calculating the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model.

[0125] In this step, the power of each power battery cell can be calculated according to the temperature of each power battery cell by using the following formula based on an extended Kalman filter formula of a preset first-order equivalent circuit model.

[0126] Specifically, the first step is to generate prior values.

[0127]

[0128] U 1,k =U 1,k-1 ·a k-1 -R 1,k-1 I k-1 ·(1-a k-1 ) (7)

[0129] V mdl,k =OCV mdl,k +I k ·R 0,k -U 1,k (8)

[0130]

[0131] Among them, formula (5) is used to calculate the ampere-hour integral, and formula (6) is used to look up the first-order equivalent circuit model parameter table, which includes the temperature T of each power battery cell. k , formula (7) is used to calculate the polarization voltage, formula (8) is used to calculate the battery voltage, and formula (9) is used to calculate the relaxation factor during the polarization process.

[0132] In formula (5) to formula (9), I k-1 is the value of the current at time k-1, Δt k-1 is the sampling time interval at time k-1, SOC is the state of charge of each power battery cell, U1 is the polarization voltage, V mdl,k is the battery voltage calculated at time k, a k is the relaxation factor of the polarization process at time k, R 0,k is the series resistance of the equivalent circuit at time k, R 1,k is the parallel resistance of the equivalent circuit at time k, τ is the relaxation time of the polarization voltage, and OCV is the open circuit voltage of the battery.

[0133] The calculation formulas of formulas (5) to (9) are written in the form of state equations as follows: formula (10) and formula (11).

[0134] X k+1 =A k X k +B k U k (10)

[0135] Y k =C k X k +D k U k (11)

[0136] In formula (10) and formula (11), A k is the state matrix, B k is the input matrix, C k is the output matrix, D k is the direct transfer matrix, k is the time. 1,k+1 =a k ·U 1,k -R 1,k ·(1-a k )·I k , V mdl,k -OCV mdl,k =U 1,k +R 0,k I kTherefore, in formula (10), X k =U 1,k , U k =I k , A k =a k , B k =R 1,k ·(1-a k ), C k =1,D k =R 0,k , Y k =V mdl,k -OCV mdl,k .

[0137] The second step is to generate the error E k .

[0138] E k =V exp,k -V mdl,k (12)

[0139] In formula (12), V exp,k is the measured voltage value of each power battery cell at time k, E k It is the error between the voltage test value and the calculated value of each power battery cell.

[0140] The third step is to calculate the feedback gain coefficient L based on the Kalman filter principle. k .

[0141]

[0142] In formula (13), A k-1 =1,∑ w is a constant.

[0143]

[0144] In formula (15), ∑ v is a constant.

[0145]

[0146] In formula (16), L k is the gain coefficient, To estimate the covariance, C k is the Jacobian matrix, is the estimated covariance update.

[0147] The fourth step is to calculate SOC for a posteriori correction.

[0148]

[0149] In formula (17), is the prior SOC obtained by integrating ampere-hours, The final power SOC of each power battery cell at time k is obtained by correcting the prior SOC through the gain coefficient and error of the Kalman filter.

[0150] It can be seen that according to the temperature T of each power battery cell k Through the above formulas (5) to (17), the power of each power battery cell can be calculated. The power calculated in this way, taking into account the different temperatures of each power battery cell, is more in line with the actual situation and has higher accuracy.

[0151] Step 106 , calculating the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity, and obtaining the first ampere-hour value corresponding to each initial whole pack SOH value.

[0152] In this step, the initial whole pack SOH value corresponding to the whole pack of power batteries can be calculated based on the calculated SOH values ​​and power of the power battery cells in the whole pack of power batteries. It should be noted that the whole pack of power batteries corresponds to a series of initial whole pack SOH values, and each initial whole pack SOH value corresponds to a first ampere-hour value. In this step, the first ampere-hour values ​​corresponding to each initial whole pack SOH value need to be obtained.

[0153] Optional, reference Figure 4 , Figure 4 This is a processing flow diagram of step 106 in the present invention. The processing step of "calculating the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity" in step 106 may specifically include:

[0154] Sub-step 31, calculating the capacity of the entire pack of power batteries according to the single cell SOH value and the power quantity based on formula (18);

[0155] C pack =min(SOC·C)+min((1-SOC)·C)(18)

[0156] In formula (18), C pack is the capacity of the entire pack of power batteries, SOC is the power, and C is the single cell capacity, wherein the single cell capacity C is equal to the product of the corrected single cell SOH value and the rated capacity of each power battery single cell.

[0157] Sub-step 32, calculating a plurality of initial whole pack SOH values ​​corresponding to the whole pack of power batteries according to the capacity of the whole pack of power batteries and based on formula (19);

[0158]

[0159] In formula (19), SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity C of each parallel power battery cell T sum.

[0160] It should be noted that since the voltage of the battery pack increases when the single cells are connected in series, and the capacity of the battery pack increases when the single cells are connected in parallel, therefore, C Tpack If all the single cells are connected in series (such as 1p96s, which is a 1-in-1 96-in-1 battery pack), the single cell capacity is equal to the battery pack capacity. The present invention only considers the series connection of batteries. If there are single cells in parallel, the parallel single cells are analyzed as a whole.

[0161] Step 108 , calculating a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value based on a preset correction formula.

[0162] Among them, one corrected whole-package SOH value corresponds to one of the first ampere-hour values.

[0163] In this step, the corrected whole pack SOH value of the whole pack of power batteries can be calculated based on the initial whole pack SOH value and the actual measured whole pack SOH value obtained, based on a preset correction formula, so that the single cell attenuation model can be parameter identified according to the corrected whole pack SOH value to generate a whole pack attenuation model.

[0164] It should be noted that the initial whole package SOH value includes a series of SOH values, each of which corresponds to an ampere-hour value.

[0165] Optional, reference Figure 5 , Figure 5 1 is a schematic diagram of the processing flow of step 108 in the present invention, and step 108 specifically includes the following sub-steps:

[0166] Sub-step 41 , obtaining the actual measured SOH value of the whole pack of power batteries obtained by actual measurement.

[0167] It should be noted that here, only the measured whole pack SOH value obtained by actual measurement of at least one whole pack of power batteries needs to be obtained, which is only used to correct the initial whole pack SOH value and calculate the corrected whole pack SOH value.

[0168] Sub-step 42, calculating a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the measured whole pack SOH value based on the following preset correction formula;

[0169]

[0170] In formula (20) and formula (21), SOH k,mod is the corrected SOH value of the whole pack of power batteries at time k, Ah k is the accumulated ampere-hour data from the start time to time k, Ah is the total ampere-hour data from the start time to the correction time, where the start time is the previous correction time, SOH pack is the initial SOH value of the whole pack of power batteries at time k before correction, SOH act is a measured SOH value of the whole pack of power batteries, and error represents SOH act With SOH pack The error between .

[0171] Step 110 , performing parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​corresponding to each corrected whole package SOH value, to generate a whole package attenuation model.

[0172] In this step, the parameters of the single cell attenuation model can be identified based on the corrected whole pack SOH value and the first ampere-hour value corresponding to each corrected whole pack SOH value, that is, the key parameters of the single cell attenuation model can be corrected, and the corrected single cell attenuation model can be used as the whole pack attenuation model to facilitate the subsequent use of the whole pack attenuation model to estimate the estimated whole pack SOH value of the whole pack of power batteries.

[0173] Optionally, step 110 specifically includes:

[0174] According to at least three of the corrected whole pack SOH values ​​and the first ampere-hour value corresponding to the at least three corrected whole pack SOH values, the capacity loss coefficient A, the activation energy Ea of battery cell decay and the preset parameter z in the single cell decay model are corrected to obtain the whole pack decay model.

[0175] Specifically, first, based on the calculated at least three corrected whole-pack SOH values ​​and the first ampere-hour value corresponding to each corrected whole-pack SOH value, the capacity loss coefficient A, the activation energy Ea of the battery cell decay and the preset parameter z in the single cell decay model shown in formula (3) and formula (4) are taken as unknowns, and the corrected values ​​of the three parameters are recalculated. Finally, the corrected values ​​of the three parameters recalculated are re-substituted into formula (3) and formula (4) to generate the whole-pack decay model.

[0176] Step 112: estimating the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model.

[0177] In this step, the estimated whole pack SOH value of the whole pack of power batteries is estimated according to the capacity loss of the whole pack of power batteries and based on the generated whole pack attenuation model. Since the whole pack attenuation model takes into account the temperature of each power battery cell in the whole pack of power batteries and the correction of the actual measured whole pack SOH value, the estimated whole pack SOH value of the whole pack of power batteries has a high accuracy rate, is closer to the actual situation, can reflect the state of the power battery itself, and the estimation effect is ideal.

[0178] It can be seen that the method for estimating the life of a power battery proposed in the present invention can take into account the temperature of each power battery cell in a whole pack of power batteries, and the whole pack attenuation model used for estimating the estimated whole pack SOH value of the whole pack of power batteries is a correction of the actual measured whole pack SOH value, and the temperature of the power battery cell is determined according to the heat generated by the cell. Therefore, the estimated whole pack SOH value estimated by the whole pack attenuation model is more accurate, closer to the actual situation, can reflect the state of the power battery itself, and the estimation effect is more ideal.

[0179] It should be noted that the method for estimating the life of a power battery proposed in the present invention can be applied to devices using batteries as energy storage units, and can also be applied to the life prediction of power batteries of electric energy equipment such as new energy vehicles and energy storage systems.

[0180] It should also be noted that the mileage life of new energy vehicles can be predicted by mapping the Ah data with the mileage data accordingly.

[0181] The present invention proposes a device for estimating the life of a power battery, referring to Figure 6 , Figure 6 FIG. 1 is a schematic diagram of the structure of the device for estimating the life of a power battery according to the present invention. Figure 6 As shown, the device 60 for estimating the life of the power battery includes:

[0182] An acquisition module 601 is used to acquire the temperature of each power battery cell in a whole pack of power batteries;

[0183] A first calculation module 602 is used to calculate the SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model;

[0184] A second calculation module 603 is used to calculate the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model;

[0185] A third calculation module 604 is used to calculate the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power, and obtain the first ampere-hour value corresponding to each initial whole pack SOH value;

[0186] a fourth calculation module 605, configured to calculate a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value, based on a preset correction formula, wherein one corrected whole pack SOH value corresponds to one first ampere-hour value;

[0187] A generating module 606, configured to perform parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​corresponding to each corrected whole package SOH value, so as to generate a whole package attenuation model;

[0188] The estimation module 607 is used to estimate the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model.

[0189] Optionally, the acquisition module 601 specifically includes:

[0190] A first calculation submodule, configured to calculate the heat generated by each power battery cell according to the current of each power battery cell in the whole pack of power batteries based on the following formula;

[0191]

[0192] In the formula, q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i;

[0193] A second calculation submodule, configured to calculate the temperature of each power battery cell according to the heat generated by each power battery cell based on the following formula;

[0194]

[0195] In the formula, T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, A area is the heat exchange area between the battery cells in the module and the environment, ρ is the density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T amb is the ambient temperature, and q0 is the heat generated by each power battery cell.

[0196] Optionally, the first calculation module 602 specifically includes:

[0197] an acquisition submodule, used for acquiring the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature;

[0198] A third calculation submodule, configured to calculate the capacity loss of each power battery cell at time i according to the temperature and the second ampere-hour value based on the following formula;

[0199]

[0200] In the formula, Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell;

[0201] A fourth calculation submodule, configured to calculate the cell SOH value of each power battery cell according to the capacity loss of each power battery cell at time i and based on the following preset cell attenuation model;

[0202]

[0203] In the formula, SOH cell is the single cell SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

[0204] Optionally, the third calculation module 604 specifically includes:

[0205] A fifth calculation submodule, configured to calculate the capacity of the entire pack of power batteries according to the single cell SOH value and the power quantity based on the following formula;

[0206] C pack =min(SOC·C)+min((1-SOC)·C)

[0207] Among them, C pack is the capacity of the whole pack of power batteries, SOC is the power, and C is the cell capacity, wherein the cell capacity C is equal to the product of the corrected cell SOH value and the rated capacity of each power battery cell;

[0208] A sixth calculation submodule, configured to calculate a plurality of initial whole pack SOH values ​​corresponding to the whole pack of power batteries according to the capacity of the whole pack of power batteries and based on the following formula;

[0209]

[0210] Among them, SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity C of each parallel power battery cell T sum.

[0211] Optionally, the fourth calculation module 605 specifically includes:

[0212] The second acquisition submodule is used to obtain the actual measured SOH value of the whole pack of power batteries obtained by actual measurement;

[0213] A seventh calculation submodule, configured to calculate a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the measured whole pack SOH value based on the following preset correction formula;

[0214]

[0215] In the formula, SOH k,mod is the corrected SOH value of the whole pack of power batteries at time k, Ah k is the accumulated ampere-hour data from the start time to time k, Ah is the total ampere-hour data from the start time to the correction time, where the start time is the previous correction time, SOH pack is the initial SOH value of the whole pack of power batteries at time k before correction, SOH act is a measured SOH value of the whole pack of power batteries, error represents SOH act With SOH pack The error between .

[0216] Optionally, the generation module 606 is specifically used to correct the capacity loss coefficient A, the activation energy Ea of battery cell decay and the preset parameter z in the single cell decay model according to at least three of the corrected whole pack SOH values ​​and the first ampere-hour value corresponding to the at least three corrected whole pack SOH values ​​to obtain the whole pack decay model.

[0217] Optionally, the estimation module 607 is specifically used to estimate the estimated whole pack SOH value of the whole pack of power batteries based on the following whole pack attenuation model;

[0218]

[0219] In the formula, SOH bag is the estimated SOH value of the whole pack of power batteries, Q i is the capacity loss of the whole pack of power batteries at time i, i=1, 2, ..., n.

[0220] It can be seen that the whole pack attenuation model in the device for estimating the life of a power battery proposed in the present invention can take into account the temperature of each power battery cell in the whole pack of power batteries, as well as the correction of the actual measured whole pack SOH value, and the temperature of the power battery cell is determined according to the heat generated by the battery cell. Therefore, the estimated whole pack SOH value estimated by the whole pack attenuation model is more accurate, closer to the actual situation, can reflect the state of the power battery itself, and the estimation effect is more ideal.

[0221] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0222] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0223] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for estimating the life of a power battery, characterized in that: include: Obtaining the temperature of each power battery cell in a whole pack of power batteries; According to the temperature, based on a preset cell attenuation model, the cell SOH value corresponding to each power battery cell is calculated; Calculating the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model; Calculating the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity, and obtaining the first ampere-hour value corresponding to each initial whole pack SOH value; Calculating a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value based on a preset correction formula, wherein one corrected whole pack SOH value corresponds to one first ampere-hour value; According to the corrected whole-package SOH value and the first ampere-hour values ​​corresponding to each corrected whole-package SOH value, parameter identification is performed on the monomer attenuation model to generate a whole-package attenuation model; Based on the whole pack attenuation model, estimating the estimated whole pack SOH value of the whole pack of power batteries; The step of calculating the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power includes: According to the single cell SOH value and the power quantity, the capacity of the whole pack of power batteries is calculated based on the following formula; C pack =min(SOC·C)+min((1-SOC)·C) Among them, C pack is the capacity of the whole pack of power batteries, SOC is the power, and C is the cell capacity, wherein the cell capacity C is equal to the product of the corrected cell SOH value and the rated capacity of each power battery cell; According to the capacity of the whole pack of power batteries, multiple initial whole pack SOH values ​​corresponding to the whole pack of power batteries are calculated based on the following formula; Among them, SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity of each parallel power battery cell C T sum.

2. The method according to claim 1, characterized in that The step of obtaining the temperature of each power battery cell in the whole pack of power batteries includes: According to the current of each power battery cell in the whole pack of power batteries, the heat generation of each power battery cell is calculated based on the following formula; In the formula, q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i; According to the heat generated by each power battery cell, the temperature of each power battery cell is calculated based on the following formula; In the formula, T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, A area is the heat exchange area between the battery cells in the module and the environment, ρ is the cell density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T amb is the ambient temperature, and q0 is the heat generated by each power battery cell.

3. The method according to claim 2, characterized in that The step of calculating the cell SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model comprises: Acquire the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature; According to the temperature and the second ampere-hour value, based on the following formula, calculating the capacity loss of each power battery cell at time i; In the formula, Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell; According to the capacity loss of each power battery cell at time i, based on the following preset cell attenuation model, calculate the cell SOH value of each power battery cell; In the formula, SOH cell is the single cell SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

4. The method according to claim 1, characterized in that: The step of calculating the corrected whole pack SOH value of the whole pack of power batteries based on the initial whole pack SOH value and the obtained measured whole pack SOH value based on a preset correction formula includes: Obtaining a measured SOH value of the whole pack of power batteries obtained by actual measurement; According to the initial whole pack SOH value and the measured whole pack SOH value, based on the following preset correction formula, a corrected whole pack SOH value of the whole pack of power batteries is calculated; In the formula, SOH k,mod is the corrected SOH value of the whole pack of power batteries at time k, Ah k is the accumulated ampere-hour data from the start time to time k, Ah is the total ampere-hour data from the start time to the correction time, where the start time is the previous correction time, SOH pack is the initial SOH value of the whole pack of power batteries at time k before correction, SOH act is a measured SOH value of the whole pack of power batteries, and error represents SOH act With SOH pack The error between .

5. The method according to claim 4, characterized in that The step of performing parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​corresponding to each corrected whole package SOH value to generate the whole package attenuation model comprises: According to at least three of the corrected whole pack SOH values ​​and the first ampere-hour value corresponding to the at least three corrected whole pack SOH values, the capacity loss coefficient A, the activation energy Ea of battery cell decay and the preset parameter z in the single cell decay model are corrected to obtain the whole pack decay model.

6. The method according to claim 1, characterized in that The step of estimating the estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model comprises: Based on the following whole pack attenuation model, estimate the estimated whole pack SOH value of the whole pack of power batteries; In the formula, SOH bag is the estimated SOH value of the whole pack of power batteries, Q i is the capacity loss of the whole pack of power batteries at time i, i=1, 2, ..., n.

7. A device for estimating the life of a power battery, characterized in that: include: An acquisition module is used to acquire the temperature of each power battery cell in a whole pack of power batteries; A first calculation module, configured to calculate the cell SOH value corresponding to each power battery cell according to the temperature and based on a preset cell attenuation model; A second calculation module, configured to calculate the power of each power battery cell according to the temperature of each power battery cell and based on an extended Kalman filter formula of a preset first-order equivalent circuit model; A third calculation module is used to calculate the initial whole pack SOH value corresponding to the whole pack of power batteries according to the single cell SOH value and the power quantity, and obtain the first ampere-hour value corresponding to each initial whole pack SOH value; a fourth calculation module, configured to calculate a corrected whole pack SOH value of the whole pack of power batteries according to the initial whole pack SOH value and the obtained measured whole pack SOH value, based on a preset correction formula, wherein one corrected whole pack SOH value corresponds to one first ampere-hour value; A generating module, configured to perform parameter identification on the monomer attenuation model according to the corrected whole package SOH value and the first ampere-hour values ​​respectively corresponding to each corrected whole package SOH value, so as to generate a whole package attenuation model; An estimation module, used for estimating an estimated whole pack SOH value of the whole pack of power batteries based on the whole pack attenuation model; The third calculation module specifically includes: A fifth calculation submodule, configured to calculate the capacity of the entire pack of power batteries according to the single cell SOH value and the power quantity based on the following formula; C pack =min(SOC·C)+min((1-SOC)·C) Among them, C pack is the capacity of the whole pack of power batteries, SOC is the power, and C is the cell capacity, wherein the cell capacity C is equal to the product of the corrected cell SOH value and the rated capacity of each power battery cell; A sixth calculation submodule, configured to calculate a plurality of initial whole pack SOH values ​​corresponding to the whole pack of power batteries according to the capacity of the whole pack of power batteries and based on the following formula; Among them, SOH pack is the initial whole package SOH value, C pack is the capacity of the whole pack of power batteries, C Tpack is the capacity of the whole pack of power batteries, that is, the rated capacity of each parallel power battery cell C T sum.

8. The device according to claim 7, characterized in that The acquisition module specifically includes: A first calculation submodule, configured to calculate the heat generated by each power battery cell according to the current of each power battery cell in the whole pack of power batteries based on the following formula; In the formula, q0 is the heat generated by each power battery cell, I i is the current of each power battery cell at time i, R 0,i With R 1,i are the resistance values ​​of two resistors of the first-order equivalent circuit model of each power battery cell at time i; A second calculation submodule, configured to calculate the temperature of each power battery cell according to the heat generated by each power battery cell based on the following formula; In the formula, T is the temperature of each power battery cell, A c is the cross-sectional area of ​​the module, A area is the heat exchange area between the battery cells in the module and the environment, ρ is the density of each power battery cell, C p is the constant pressure heat capacity of each power battery cell, κ is the thermal conductivity, T amb is the ambient temperature, and q0 is the heat generated by each power battery cell.

9. The device according to claim 8, characterized in that The first calculation module specifically includes: an acquisition submodule, used for acquiring the temperature of each power battery cell and the second ampere-hour value of each power battery cell at the temperature; A third calculation submodule, configured to calculate the capacity loss of each power battery cell at time i according to the temperature and the second ampere-hour value based on the following formula; In the formula, Q i is the capacity loss of each power battery cell at time i, A is the capacity loss coefficient of each power battery cell, T i is the temperature of each power battery cell at time i, Ah i is the ampere-hour value of each power battery cell at temperature T, time i, Ea is the activation energy of attenuation of each power battery cell, and z is the preset parameter of each power battery cell; A fourth calculation submodule, configured to calculate the cell SOH value of each power battery cell according to the capacity loss of each power battery cell at time i and based on the following preset cell attenuation model; In the formula, SOH cell is the SOH value of each power battery cell, Q i is the capacity loss of each power battery cell at time i, i=1, 2, ..., n.

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