SOH correction method and device of battery pack

Abstract

The invention discloses an SOH correction method and device of a battery pack, and relates to the technical field of new energy automobile battery management. The method comprises the following steps: testing the cycle life of a battery cell to obtain a standard characteristic matrix of charging and discharging of a battery pack; and then dividing real-time charging and discharging data through a preset current interval and a preset temperature interval, constructing an actual measurement characteristic matrix of charging and discharging of the battery pack, determining an SOH correction value through the standard characteristic matrix and the actual measurement characteristic matrix, and correcting an SOH calculation value through the SOH correction value. By comparing the standard charging and discharging data of the battery cell in the battery pack with the self charging and discharging capacity in the actual use process and combining with the SOH calculation algorithm of the battery pack, the defect that the SOH algorithm is poor in precision in the prior art is overcome, and the accuracy of the SOH algorithm is improved through the standard charging and discharging data and the actual charging and discharging data of the battery pack. And the correction accuracy of the SOH value is further improved, so that the SOH value is closer to the real life value of the battery pack, and the accuracy of the SOH value of the battery pack is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle battery management, and in particular relates to a method and device for correcting the SOH of a battery pack. Background Art

[0002] As the number of new energy vehicles increases, each vehicle uses the battery cells in the battery pack in different conditions. Differences in various factors lead to differences in the life of each vehicle's battery pack. The SOH (State Of Health) of the battery pack reflects the battery pack's power, energy, charge and discharge power, and other states. It is an important indicator for evaluating the current health level and remaining life of the battery pack. The SOH value is crucial for the use of new energy vehicles. When the calculated SOH value is higher than the actual value, the battery cell life in the battery pack will decay faster or various faults will occur. When the calculated SOH value is lower than the actual value, the car's driving power will decay or charging will be prolonged, so accurate calculation of SOH is very important.

[0003] The battery cell is the core component of the battery pack, so the current evaluation of the battery pack SOH is usually to test and evaluate the battery cell, for example, based on the cumulative charge and discharge ampere-hours and calendar aging algorithm. Some technicians also combine these two algorithms to calculate the life of the battery pack. However, these algorithms have certain requirements on the accuracy of battery pack current collection and time calculation, otherwise it will cause calculation errors, and as time goes by, this error will become larger and larger, and finally lead to the deviation of SOH accuracy. This deviation in accuracy will affect the use of the battery cells in the battery pack, and then affect the use of new energy vehicles. Therefore, there is an urgent need for a battery pack SOH correction method and device to solve the defects of the prior art. Summary of the invention

[0004] The present invention aims to provide a method and device for correcting the SOH of a battery pack to solve the above-mentioned technical problems. A standard characteristic matrix is ​​constructed by cycle life testing of battery cells in the battery pack and a measured characteristic matrix is ​​constructed by real-time charge and discharge data. The SOH value is corrected by the standard characteristic matrix and the measured characteristic matrix to improve the accuracy of the SOH value of the battery pack.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for correcting the SOH of a battery pack, which is applicable to a battery pack including a battery cell, and includes:

[0006] Perform cycle life tests on the battery cells to obtain several charge and discharge cycle life curves; fit several charge and discharge cycle life curves according to preset current ranges to obtain a standard characteristic matrix of battery pack charge and discharge;

[0007] Collecting real-time charge and discharge data of the battery pack, dividing the real-time charge and discharge data into preset current intervals and preset temperature intervals, and constructing a measured characteristic matrix of the battery pack charge and discharge;

[0008] Obtain a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtain a SOH correction value based on the difference matrix;

[0009] The accumulated charge and discharge data of the battery pack is obtained, and a SOH calculated value of the battery pack is calculated according to the accumulated charge and discharge data of the battery pack, and the SOH calculated value is corrected according to the SOH correction value.

[0010] It can be understood that, compared with the prior art, the present invention performs cycle life tests on the cells in the battery pack, and fits the charge and discharge cycle life curve according to a preset current range to obtain a standard characteristic matrix of the battery pack charge and discharge; then, by collecting the real-time charge and discharge data of the battery pack, the real-time charge and discharge data is divided by the current range and the preset temperature range to construct a measured characteristic matrix of the battery pack charge and discharge, and then the SOH correction value is determined by the standard characteristic matrix and the measured characteristic matrix, and the SOH calculated value is corrected by the SOH correction value. The present invention makes up for the poor accuracy of the SOH algorithm commonly used in the prior art by comparing the standard charge and discharge data of the cells in the battery pack with their own charge and discharge capabilities during actual use, and combining it with the battery pack SOH calculation algorithm. Through the two perspectives of the standard charge and discharge data and the actual charge and discharge data of the battery pack, the correction accuracy of the SOH value is further improved, so that the SOH value is closer to the actual life value of the battery pack itself, and the accuracy of the SOH value of the battery pack is improved.

[0011] As a preferred solution, a cycle life test is performed on the battery cell to obtain a number of charge and discharge cycle life curves; a number of charge and discharge cycle life curves are fitted according to a preset current interval to obtain a standard characteristic matrix of battery pack charge and discharge, specifically including: the preset current interval includes: a first current interval and a second current interval;

[0012] Perform cycle life test on the battery cell to obtain several charge and discharge cycle life curves in a preset SOH range;

[0013] Fitting a number of charge-discharge cycle life curves to obtain expansions corresponding to the number of charge-discharge cycle life curves and data matrices corresponding to the expansions;

[0014] Analyze the expansions corresponding to several charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the several charge-discharge cycle life curves;

[0015] According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval;

[0016] A standard characteristic matrix for charging and discharging the battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

[0017] This preferred solution constructs a standard characteristic matrix of the battery pack by performing a cycle life test on the battery cells in the battery pack and fitting the standard charge and discharge data of the battery cells in the battery pack through the cycle life test. This achieves the characterization of the standard charge and discharge data of the battery pack and provides an accurate data basis for the subsequent correction of the SOH value of the battery pack.

[0018] As a preferred solution, real-time charge and discharge data of the battery pack is collected, and the real-time charge and discharge data is divided into preset current intervals and preset temperature intervals to construct a measured characteristic matrix of the battery pack charge and discharge, which specifically includes:

[0019] Collect real-time charging and discharging data of the battery pack, including charging data and discharging data;

[0020] The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval;

[0021] The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range;

[0022] The first measured discharge curve, the second measured discharge curve, the first measured charging curve and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct the measured characteristic matrix of battery pack charging and discharging.

[0023] This preferred solution divides the real-time charge and discharge data of the battery pack into temperature ranges and current ranges to obtain data that is more in line with the daily usage process of the battery pack, thereby constructing a measured characteristic matrix of the battery pack, achieving the characterization of the measured charge and discharge data of the battery pack, and providing accurate data basis for the subsequent correction of the SOH value of the battery pack.

[0024] As a preferred solution, a difference matrix is ​​obtained according to the standard feature matrix and the measured feature matrix, specifically including:

[0025] Extracting a measured feature segment curve of the measured feature matrix and a measured feature matrix corresponding to the measured feature segment curve;

[0026] According to the characteristic segment curve and the characteristic matrix corresponding to the characteristic segment curve, extract the standard characteristic segment curve of the standard characteristic matrix and the standard characteristic matrix corresponding to the standard characteristic segment curve;

[0027] A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

[0028] As a preferred solution, the SOH correction value is obtained based on the difference matrix, specifically including:

[0029] Filter the minimum value of the difference matrix and obtain the SOH data set;

[0030] The SOH data set is filtered to remove outliers in the SOH data set, and the removed outliers are filled according to the sliding algorithm to obtain the corrected SOH data set;

[0031] Calculate the average of the corrected SOH data set to obtain the corrected SOH value.

[0032] As a preferred solution, the cumulative charge and discharge data of the battery pack is obtained, and the SOH calculated value of the battery pack is calculated based on the cumulative charge and discharge data of the battery pack, and the SOH calculated value is corrected according to the SOH correction value, specifically including:

[0033] Obtain the cumulative charge and discharge data of the battery pack;

[0034] Obtain the SOH calculation value of the battery pack according to the preset algorithm;

[0035] The SOH difference between the SOH calculated value and the SOH corrected value is calculated, and the SOH calculated value is corrected according to the SOH difference and a preset correction factor.

[0036] This preferred solution obtains the SOH correction value through the standard characteristic matrix and the measured characteristic matrix. On the one hand, the standard characteristic matrix can compensate for the SOH accuracy deviation caused by the battery pack over time. On the other hand, the measured characteristic matrix can fully consider the impact of the SOH accuracy of the battery pack during use. Finally, the SOH calculated value is corrected in combination with the correction factor, thereby improving the correction accuracy of the SOH calculated value.

[0037] Accordingly, an embodiment of the present invention provides a SOH correction device for a battery pack, which is applicable to a battery pack including battery cells, and includes: a standard characteristic matrix calculation module, a measured characteristic matrix calculation module, a SOH correction value calculation module, and a SOH correction module;

[0038] Among them, the standard characteristic matrix calculation module is used to perform cycle life test on the battery cell to obtain several charge and discharge cycle life curves; fit several charge and discharge cycle life curves according to the preset current range to obtain the standard characteristic matrix of battery pack charge and discharge;

[0039] The measured characteristic matrix calculation module is used to collect real-time charge and discharge data of the battery pack, divide the real-time charge and discharge data into preset current intervals and preset temperature intervals, and construct a measured characteristic matrix of the battery pack charge and discharge;

[0040] The SOH correction value calculation module is used to obtain a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtain the SOH correction value based on the difference matrix;

[0041] The SOH correction module is used to obtain the cumulative charge and discharge data of the battery pack, calculate the SOH calculated value of the battery pack according to the cumulative charge and discharge data of the battery pack, and correct the SOH calculated value according to the SOH correction value.

[0042] As a preferred solution, the standard characteristic matrix calculation module includes: a standard characteristic matrix calculation unit;

[0043] In the standard characteristic matrix calculation unit, the preset current interval includes: a first current interval and a second current interval;

[0044] The standard characteristic matrix calculation unit is used to perform cycle life test on the battery cell to obtain several charge and discharge cycle life curves in the preset SOH range;

[0045] Fitting a number of charge-discharge cycle life curves to obtain expansions corresponding to the number of charge-discharge cycle life curves and data matrices corresponding to the expansions;

[0046] Analyze the expansions corresponding to several charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the several charge-discharge cycle life curves;

[0047] According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval;

[0048] A standard characteristic matrix for charging and discharging the battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

[0049] As a preferred solution, the measured characteristic matrix calculation module includes: a measured characteristic matrix calculation unit;

[0050] The measured characteristic matrix calculation unit is used to collect real-time charging and discharging data of the battery pack, and the real-time charging and discharging data includes: charging data and discharging data;

[0051] The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval;

[0052] The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range;

[0053] The first measured discharge curve, the second measured discharge curve, the first measured charging curve and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct the measured characteristic matrix of battery pack charging and discharging.

[0054] As a preferred solution, the SOH correction value calculation module includes: a difference matrix calculation unit;

[0055] The difference matrix calculation unit is used to extract the measured feature segment curve of the measured feature matrix and the measured feature matrix corresponding to the measured feature segment curve;

[0056] According to the characteristic segment curve and the characteristic matrix corresponding to the characteristic segment curve, extract the standard characteristic segment curve of the standard characteristic matrix and the standard characteristic matrix corresponding to the standard characteristic segment curve;

[0057] A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

[0058] It can be understood that, compared with the prior art, the present device performs cycle life tests on the cells in the battery pack, and fits the charge and discharge cycle life curve according to the preset current range to obtain the standard characteristic matrix of the battery pack charge and discharge; then, by collecting the real-time charge and discharge data of the battery pack, the real-time charge and discharge data is divided by the current range and the preset temperature range, and the measured characteristic matrix of the battery pack charge and discharge is constructed, and then the SOH correction value is determined by the standard characteristic matrix and the measured characteristic matrix, and the SOH calculated value is corrected by the SOH correction value. The present device makes up for the poor accuracy of the SOH algorithm commonly used in the prior art by comparing the standard charge and discharge data of the cells in the battery pack with their own charge and discharge capabilities during actual use, and combines it with the battery pack SOH calculation algorithm. Through the two perspectives of the standard charge and discharge data and the actual charge and discharge data of the battery pack, the correction accuracy of the SOH value is further improved, so that the SOH value is closer to the actual life value of the battery pack itself, and the accuracy of the SOH value of the battery pack is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 : A flow chart of the steps of a method for correcting SOH of a battery pack provided by an embodiment of the present invention;

[0060] Figure 2 : A flow chart of another method for correcting SOH of a battery pack provided by an embodiment of the present invention;

[0061] Figure 3 : A schematic diagram of an OCV curve of a lithium iron phosphate battery cell provided in an embodiment of the present invention;

[0062] Figure 4 : A structural schematic diagram of a SOH correction device for a battery pack provided by an embodiment of the present invention;

[0063] Among them, 201: standard characteristic matrix calculation module; 202: measured characteristic matrix calculation module; 203: SOH correction value calculation module; 204: SOH correction module. DETAILED DESCRIPTION

[0064] 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.

[0065] First, some of the terms involved in the embodiments of the present invention are explained. The SOH (State Of Health) of a battery pack is an important indicator for measuring the degree of performance degradation of a battery pack, and is used to describe the current health and performance of the battery pack. The BMS (Battery Management System) of a battery pack is a system for managing the battery pack. Its main function is to intelligently manage and maintain each battery pack unit, prevent the battery pack from being overcharged and over-discharged, effectively extend the service life of the battery pack, and monitor the status of the battery pack to ensure the safe operation of the battery pack. The NVM (Non-Volatile Memory) in a car is a storage device that can permanently store data. NVM is widely used in the automotive field, especially in situations where critical data (such as fault records, setting parameters and calibration data, etc.) need to be permanently stored. The DoD (Depth of discharge) of a battery pack refers to the percentage of the amount of electricity discharged by the battery pack during use to its rated capacity. That is, when the battery pack starts to discharge from the upper limit voltage to the lower limit voltage, all the discharged electricity is defined as 100% of the discharge depth.

[0066] With the continuous development of new energy technologies, new energy vehicles have become increasingly popular. Due to the large number of new energy vehicles, different types of new energy vehicles have very different usage conditions for the cells in the battery pack. For example, the battery pack is used in different environments and has different types of cells in the battery pack. These differences in factors lead to large differences in the life of the cells in each battery pack. By calculating the SOH value of the battery pack, the health status and performance of the battery pack can be reflected. If the calculated SOH value is higher than the actual SOH value, the BMS will provide a charge and discharge power that exceeds the capacity of the battery pack cell. Long-term use will cause the battery pack cell life to decay faster. If the calculated SOH value is lower than the actual SOH value, the BMS will provide a lower charge and discharge power, which seriously affects the normal use of the battery pack. It can be seen that accurate calculation of the SOH value of the battery pack is crucial to the subsequent development of new energy vehicles.

[0067] However, the current methods for calculating the SOH value of battery packs mostly use data obtained through cumulative charge and discharge ampere-hours and calendar aging correction. However, this algorithm has high requirements for the current collection accuracy and time calculation of the battery pack, otherwise it will cause calculation errors. Moreover, as the battery pack is used, the error of the SOH value calculated by this method will become larger and larger, which seriously affects the status assessment of the battery pack.

[0068] Embodiment 1

[0069] Please refer to Figure 1, is a step flow chart of a SOH correction method for a battery pack provided in an embodiment of the present invention, including steps S101 to S104.

[0070] Step S101: Perform a cycle life test on the battery cell to obtain a number of charge and discharge cycle life curves; fit the number of charge and discharge cycle life curves according to a preset current range to obtain a standard characteristic matrix of battery pack charge and discharge.

[0071] In this embodiment, a cycle life test is performed on the battery cell to obtain a number of charge and discharge cycle life curves; the number of charge and discharge cycle life curves are fitted according to the preset current interval to obtain a standard characteristic matrix of battery pack charge and discharge, specifically including: the preset current interval includes: a first current interval and a second current interval;

[0072] Perform cycle life test on the battery cell to obtain several charge and discharge cycle life curves in a preset SOH range;

[0073] Fitting a number of charge-discharge cycle life curves to obtain expansions corresponding to the number of charge-discharge cycle life curves and data matrices corresponding to the expansions;

[0074] Analyze the expansions corresponding to several charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the several charge-discharge cycle life curves;

[0075] According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval;

[0076] A standard characteristic matrix for charging and discharging the battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

[0077] This embodiment performs a cycle life test on the battery cells in the battery pack and fits the standard charge and discharge data of the battery cells in the battery pack through the cycle life test, thereby constructing a standard characteristic matrix of the battery pack, achieving the characterization of the standard charge and discharge data of the battery pack, and providing an accurate data basis for the subsequent correction of the SOH value of the battery pack.

[0078] It should be noted that the cycle life test refers to monitoring the changes in battery pack capacity and performance by simulating the charge and discharge process of the battery pack in actual use, thereby predicting the overall life of the battery pack. The cycle life test is intended to evaluate the performance retention ability of the battery pack after multiple charge and discharge cycles. In the cycle life test, a 1 / 3C current is generally used for the experiment. The 1 / 3C current refers to the current corresponding to 1 / 3 of the battery pack capacity C. 5A to 10A is a small current range for the battery cells in the battery pack, which can reduce the degree of polarization of the battery cells and make the charge and discharge cycle life curve obtained by the cycle life test more stable. Therefore, in the embodiment of the present invention, the first current interval is set to 1 / 3C current, and the second current interval is set to 5A to 10A.

[0079] In an optional embodiment, a cycle life test is performed on the battery cells in the battery pack according to currents of 1 / 3C, 5A and 10A to obtain a charge and discharge cycle life curve in the range of SOH=100% to 80% (i.e., a preset SOH range); the charge and discharge cycle life curve is fitted with a step size of 1% to obtain 21 charge and discharge cycle life curves (for example, SOH=90%, 91%, etc.), as well as an expanded form corresponding to the charge and discharge cycle life curve and a data matrix corresponding to the expanded form.

[0080] The expansion corresponding to each charge and discharge cycle life curve and the data matrix corresponding to the expansion are analyzed to obtain the characteristic segment curve, and the characteristic segment curve is fitted by Taylor expansion to obtain the first charge characteristic segment matrix and the first discharge characteristic segment matrix at 1 / 3C current, as well as the second charge characteristic segment matrix and the second discharge characteristic segment matrix at 5A to 10A.

[0081] The first discharge feature segment matrix includes matrix G1, matrix G2 and matrix G3, the first charge feature segment matrix includes matrix G4, matrix G5 and matrix G6, the second discharge feature segment matrix includes matrix G7, matrix G8 and matrix G9, and the second charge feature segment matrix includes matrix G 10 , matrix G 11 and the matrix G 12 By analogy, the 21 charge-discharge cycle life curves correspond to 21 groups of G1 to G 12 The matrix of .

[0082] Through 21 groups G1 to G 12 The matrix forms the standard characteristic matrix of battery pack charging and discharging.

[0083] In some implementations of this embodiment, the charge-discharge cycle life curve is fitted with a step size of 1% to obtain 21 charge-discharge cycle life curves, as well as the expansions corresponding to the charge-discharge cycle life curves and the data matrix corresponding to the expansions.

[0084] in, It represents the expansion of the charge-discharge cycle life curve when SOH=100% under 1 / 3C condition.

[0085] It represents the expansion of the charge-discharge cycle life curve when SOH=99.1% under 1 / 3C conditions, and so on. It represents the expansion of the charge-discharge cycle life curve when SOH=80% under 1 / 3C condition. In the expansion, the parameters in F(t1) are all obtained by fitting each charge-discharge cycle life curve through Taylor expansion, and they are all related to the charge-discharge parameters.

[0086] Among them, the matrix G is used to represent the data matrix corresponding to the expansion. Specifically,

[0087] By analyzing the expansion corresponding to the charge-discharge cycle life curve and the data matrix corresponding to the expansion, the characteristic segment curve in the charge-discharge cycle life curve is obtained, and then the characteristic segment curve is fitted by Taylor expansion to obtain the first charge characteristic segment matrix G4~G6 and the first discharge characteristic segment matrix G1~G3 at 1 / 3C current, and the second charge characteristic segment matrix G under 5A to 10A is obtained. 10 ~G 12 and the second discharge feature segment matrices G7-G9.

[0088] in,

[0089] Through 21 charge-discharge cycle life curves, 21 groups of G1 to G 12 The matrix, and according to 21 groups G1 to G 12 The matrix forms the standard characteristic matrix of battery pack charge and discharge, and the 21 groups G1 to G 12 The matrix is ​​stored in NVM through BMS.

[0090] It should be noted that since the actual operating conditions of new energy vehicles are not the same, the battery pack is charged and discharged at different rates and different depths of discharge (Depth of discharge, DoD) at -30°C to 60°C, resulting in differences in the conditions inside the battery cells. Therefore, step S102 of this embodiment starts from the actual operating conditions of the battery pack, collects real-time charge and discharge data under charging conditions and discharging conditions, and divides them into current ranges and temperature ranges.

[0091] Step S102: collecting real-time charge and discharge data of the battery pack, dividing the real-time charge and discharge data according to preset current intervals and preset temperature intervals, and constructing a measured characteristic matrix of the charge and discharge of the battery pack.

[0092] In this embodiment, real-time charge and discharge data of the battery pack is collected, and the real-time charge and discharge data is divided into current intervals and preset temperature intervals to construct a measured characteristic matrix of the charge and discharge of the battery pack, which specifically includes:

[0093] Collect real-time charging and discharging data of the battery pack, including charging data and discharging data;

[0094] The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval;

[0095] The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range;

[0096] The first measured discharge curve, the second measured discharge curve, the first measured charging curve and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct the measured characteristic matrix of battery pack charging and discharging.

[0097] In an optional embodiment, the real-time charge and discharge data of the battery pack can be collected by the BMS. The charge and discharge data of the battery pack can be collected by the built-in collection circuit of the BMS. The real-time charge and discharge data can also be collected by setting a corresponding data collector on the battery pack and transmitted to the BMS.

[0098] It should be noted that the preset temperature range of this embodiment refers to the temperature range of 15°C to 35°C, which is the most suitable temperature range for charging and discharging cells of new energy vehicles, and the thermal management of new energy vehicles usually keeps the cells in this temperature range. It should be noted that this temperature range is determined by the technicians through historical experiments, and other similar temperature ranges can also be modified by the technicians according to specific needs, so as to be applied to step S102 of this embodiment.

[0099] In this embodiment, real-time charge and discharge data of the battery pack are collected, and the charging data and discharge data in the temperature range of 15°C to 35°C are screened out to obtain the first measured discharge curve and the first measured charge curve at a current of 1 / 3C, as well as the second measured discharge curve and the second measured charge curve at a current of 5A to 10A.

[0100] The first measured discharge curve is fitted by Taylor sixth-order expansion to obtain the first measured discharge characteristic segment curve and the first discharge characteristic matrix, wherein the first measured discharge characteristic segment curve is expressed as F(t)=a2*t 6 +b2*t 5 +c2*t 4 +d2*t 3 +e2*t 2 +f2*t+g2, the first discharge characteristic matrix is ​​expressed as B=[a2 b2 c2 d2 e2 f2 g2].

[0101] The first measured charging curve is fitted by Taylor sixth-order expansion to obtain the first measured charging characteristic segment curve and the first charging characteristic matrix, wherein the first measured charging characteristic segment curve is expressed as F(t)=a4*t 6 +b4*t 5 +c4*t 4 +d4*t 4 +e4*t 4 +f4*t+g4, the first charging characteristic matrix is ​​expressed as D=[a4b4c4d4e4f4g4].

[0102] The second measured charging curve is fitted by Taylor sixth-order expansion to obtain the second measured charging characteristic segment curve and the second charging characteristic matrix, wherein the second measured charging characteristic segment curve is expressed as F(t)=a1*t 6 +b1*t 5 +c1*t 4 +d1*t 3 +e1*t 2 +f1*t+g1, the second charging characteristic matrix is ​​expressed as A=[a1 b1 c1 d1 e1 f1 g1].

[0103] The second measured discharge curve is fitted by Taylor sixth-order expansion to obtain the second measured discharge characteristic segment curve and the second discharge characteristic matrix, wherein the second measured discharge characteristic segment curve is expressed as F(t)=a3*t 6 +b3*t 5 +c3*t 4 +d3*t 3 +e3*t 3 +f3*t+g3, the second discharge characteristic matrix is ​​expressed as C=[a3 b3 c3 d3 e3 f3 g3].

[0104] A measured characteristic matrix of battery pack charging and discharging is constructed based on the first measured discharge characteristic segment curve and the first discharge characteristic matrix, the first measured charge characteristic segment curve and the first charge characteristic matrix, the second measured charge characteristic segment curve and the second charge characteristic matrix, and the second measured discharge characteristic segment curve and the second discharge characteristic matrix.

[0105] Among them, the parameters in F(t) are obtained by Taylor expansion fitting, which are all related to the charging data and the discharging data, and the parameters in matrices A, B, C and D are all related to the charging data and the discharging data.

[0106] This embodiment divides the real-time charge and discharge data of the battery pack into temperature intervals and current intervals to obtain data that is more in line with the daily use process of the battery pack, thereby constructing a measured characteristic matrix of the battery pack, achieving the characterization of the measured charge and discharge data of the battery pack, and providing accurate data basis for the subsequent correction of the SOH value of the battery pack.

[0107] Step S103: Obtain a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtain a SOH correction value based on the difference matrix.

[0108] In this embodiment, obtaining a difference matrix according to the standard feature matrix and the measured feature matrix specifically includes:

[0109] Extracting a measured feature segment curve of the measured feature matrix and a measured feature matrix corresponding to the measured feature segment curve;

[0110] According to the characteristic segment curve and the characteristic matrix corresponding to the characteristic segment curve, extract the standard characteristic segment curve of the standard characteristic matrix and the standard characteristic matrix corresponding to the standard characteristic segment curve;

[0111] A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

[0112] In an optional embodiment, the BMS compares the measured feature segment curve and the measured feature matrix corresponding to the measured feature segment curve with the standard feature segment curve and the standard feature matrix in the corresponding feature segment to obtain a difference matrix.

[0113] Specifically, first obtain the measured characteristic curve F(t)=a1*t of the battery pack 6 +b1*t 5 +c1*t 4 +d1*t 3 +e1*t 2 +f1*t+g1 and the measured characteristic matrix A=[a1 b1 c1 d1 e1 f1 g1] corresponding to the measured characteristic segment curve. At this time, the standard characteristic segment curve and standard characteristic matrix of the standard characteristic matrix in the corresponding characteristic segment are as follows:

[0114]

[0115] A1=[a′1 b′1 c′1 d′1 e′1 f′1 g′1],

[0116]

[0117] A2=[a′2 b′2 c′2 d′2 e′2 f′2 g′2],

[0118] ······

[0119]

[0120] A 21 =[a′ 21 b′ 21 c′ 21 d′ 21 e′ 21 f′ 21 g′ 21 ],

[0121] Then, the difference matrix is ​​obtained based on the measured feature segment curve, the measured feature matrix, the standard feature segment curve and the standard feature matrix, as shown below:

[0122]

[0123] Among them, in the difference matrix d 01 d 02 …d 021 In , the value represents the closeness between the measured feature segment curve, the measured feature matrix and the standard feature matrix in the corresponding feature segment and the standard feature matrix. The smaller the value, the closer it is.

[0124] In this embodiment, the SOH correction value is obtained based on the difference matrix, specifically including:

[0125] Filter the minimum value of the difference matrix and obtain the SOH data set;

[0126] The SOH data set is filtered to remove outliers in the SOH data set, and the removed outliers are filled according to the sliding algorithm to obtain the corrected SOH data set;

[0127] Calculate the average of the corrected SOH data set to obtain the corrected SOH value.

[0128] In an optional embodiment, by screening the minimum value of the difference matrix under different time periods and different charge and discharge currents, SOH1, SOH2, SOH3, ..., SOH10 , determine the SOH data set, filter the SOH data set, remove the outliers, and then use the sliding method (SOH 11 , SOH 12 …) to obtain a corrected SOH data set, and calculate the average value of the corrected SOH data set to obtain a corrected SOH value, which is defined as SOH′0.

[0129] In an optional embodiment, the SOH data set is filtered. The filtering process can be performed by a statistical method. First, the standard deviation of the SOH data set is calculated, and the SOH data set is filtered according to a preset standard deviation range. A normal distribution graph of the SOH data set can also be constructed to filter the SOH data set through a normal distribution curve.

[0130] Step S104: Acquire the cumulative charge and discharge data of the battery pack, calculate the SOH calculated value of the battery pack according to the cumulative charge and discharge data of the battery pack, and correct the SOH calculated value according to the SOH correction value.

[0131] In this embodiment, the cumulative charge and discharge data of the battery pack is obtained, and the SOH calculated value of the battery pack is calculated according to the cumulative charge and discharge data of the battery pack, and the SOH calculated value is corrected according to the SOH correction value, specifically including:

[0132] Obtain the cumulative charge and discharge data of the battery pack;

[0133] Obtain the SOH calculation value of the battery pack according to the preset algorithm;

[0134] The SOH difference between the SOH calculated value and the SOH corrected value is calculated, and the SOH calculated value is corrected according to the SOH difference and a preset correction factor.

[0135] In an optional embodiment, the accumulated charge and discharge data of the battery pack is obtained, and the accumulated charge and discharge data of the battery pack includes: accumulated ampere-hours, total ampere-hours and calendar life, and the SOH calculation value of the battery pack is calculated according to a preset algorithm Then calculate SOH 初始值 The difference between the SOH difference ΔSOH and the SOH correction value SOH′0 is obtained, and the SOH calculated value is corrected according to the SOH difference ΔSOH and the preset correction factor, wherein the corrected SOH calculated value is defined as SOH 修正后 , SOH 修正后 =SOH 初始值 +α*ΔSOH, α is the preset correction factor.

[0136] In an optional embodiment, as the battery pack is continuously used, the SOH value of the battery pack is constantly changing. 11, SOH 12 …SOH n The same SOH sliding value is used to continuously correct SOH′0 in a sliding manner, and SOH′0, SOH′1…SOH′ are obtained. n Equal SOH correction value, and based on SOH′0, SOH′1…SOH′ n During the use of new energy vehicles, the calculated SOH value is continuously corrected to obtain a SOH that is more in line with the actual life of the battery pack.

[0137] This embodiment obtains the SOH correction value through the standard characteristic matrix and the measured characteristic matrix. On the one hand, the standard characteristic matrix can compensate for the SOH accuracy deviation caused by the use of the battery pack over time. On the other hand, the measured characteristic matrix can fully consider the impact of the SOH accuracy of the battery pack during use. Finally, the SOH calculated value is corrected in combination with the correction factor, thereby improving the correction accuracy of the SOH calculated value.

[0138] In an alternative embodiment, please refer to Figure 2 , is a flow chart of another SOH correction method for a battery pack provided by an embodiment of the present invention, such as Figure 2 As shown, the cycle life and calendar life of the battery pack are tested, recorded and analyzed, and then the curve of the cycle data is obtained based on the charge and discharge data of the cycle life in the range of SOH = 100% and 80%, and fitted by the sixth-order Taylor expansion; by distinguishing the charge and discharge type and current size in the normal temperature section, the corresponding characteristic segment curve and characteristic matrix are obtained respectively, and the characteristic matrix is ​​stored through the BMS in the car; then the actual charge and discharge data of the whole vehicle is screened by the BMS, and the screening is performed according to the charge and discharge type and current size, and the actual characteristic matrix A, B, C, D is obtained by curve fitting of the characteristic segment, and the difference matrix is ​​calculated by the actual characteristic matrix A, B, C, D and the stored characteristic matrix to obtain the most similar curve to determine the closest SOH value. Then, the actual characteristic matrix and the stored characteristic matrix are compared to obtain multiple groups of corresponding SOH1, SOH2, SOH3...SOH n , after removing the abnormal values, take 10 values ​​as the average value to get the SOH correction value; then BMS uses the correction factor to make the SOH calculation value tend to the SOH correction value based on the original SOH calculation value, and obtains a more accurate SOH value. Later, during the use of the electric vehicle, the BMS collects different data for screening, differentiation and fitting, and gradually iterates the SOH correction value, so that the SOH value obtained during the battery pack life decay process is closer to the battery pack life.

[0139] In an alternative embodiment, please refer to Figure 3, is a schematic diagram of an OCV curve of a lithium iron phosphate battery cell provided in an embodiment of the present invention, wherein the OCV (Open Circuit Voltage) test refers to measuring the voltage value of the battery pack in an open circuit (no current passing) state. Figure 3 As shown in the figure, the OCV curve of the lithium iron phosphate battery contains three characteristic segments, namely the charging end, the discharging end and the OCV platform area inflection point, which are △V=409Mv, 29Mv, and 100mV intervals respectively. By screening the current data that meets these three characteristic segments during discharge, and performing a sixth-order Taylor expansion fitting, the matrix corresponding to the characteristic segment is obtained, and compared with the characteristic segment matrix stored in the NVM of the BMS, SOH1, SOH2, SOH3…SOH 10 , SOH 11 , SOH 12 …, the average of 10 values ​​is selected as the SOH correction value, so that the SOH calculation value obtained by the SOH calculation algorithm used in daily life is more close to the actual life of the battery pack.

[0140] This embodiment performs a cycle life test on the cells in the battery pack, and fits the charge and discharge cycle life curve according to a preset current range to obtain a standard characteristic matrix of the battery pack charge and discharge; then, by collecting the real-time charge and discharge data of the battery pack, the real-time charge and discharge data is divided by current range and preset temperature range to construct a measured characteristic matrix of the battery pack charge and discharge, and then the SOH correction value is determined by the standard characteristic matrix and the measured characteristic matrix, and the SOH calculated value is corrected by the SOH correction value. This embodiment makes up for the poor accuracy of the SOH algorithm commonly used in the prior art by comparing the standard charge and discharge data of the cells in the battery pack with their own charge and discharge capabilities during actual use, and combining it with the battery pack SOH calculation algorithm. From the two perspectives of the standard charge and discharge data and the actual charge and discharge data of the battery pack, the accuracy of the correction of the SOH value is further improved, so that the SOH value is closer to the actual life value of the battery pack itself, and the accuracy of the SOH value of the battery pack is improved.

[0141] Embodiment 2

[0142] Please refer to Figure 4 , which is a structural schematic diagram of a SOH correction device for a battery pack provided in an embodiment of the present invention, is applicable to a battery pack including battery cells, and includes: a standard characteristic matrix calculation module 201, a measured characteristic matrix calculation module 202, a SOH correction value calculation module 203 and a SOH correction module 204.

[0143] Among them, the standard characteristic matrix calculation module 201 is used to perform cycle life test on the battery cell to obtain a number of charge and discharge cycle life curves; fit a number of charge and discharge cycle life curves according to a preset current range to obtain a standard characteristic matrix of battery pack charge and discharge.

[0144] In this embodiment, the standard characteristic matrix calculation module 201 includes: a standard characteristic matrix calculation unit;

[0145] In the standard characteristic matrix calculation unit, the preset current interval includes: a first current interval and a second current interval;

[0146] The standard characteristic matrix calculation unit is used to perform cycle life test on the battery cell and obtain several charge and discharge cycle life curves in a preset SOH range;

[0147] Fitting a number of charge-discharge cycle life curves to obtain expansions corresponding to the number of charge-discharge cycle life curves and data matrices corresponding to the expansions;

[0148] Analyze the expansions corresponding to several charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the several charge-discharge cycle life curves;

[0149] According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval;

[0150] A standard characteristic matrix for charging and discharging the battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

[0151] The measured characteristic matrix calculation module 202 is used to collect real-time charge and discharge data of the battery pack, divide the real-time charge and discharge data into preset current intervals and preset temperature intervals, and construct a measured characteristic matrix of the charge and discharge of the battery pack.

[0152] In this embodiment, the measured characteristic matrix calculation module 202 includes: a measured characteristic matrix calculation unit;

[0153] The measured characteristic matrix calculation unit is used to collect real-time charging and discharging data of the battery pack, and the real-time charging and discharging data includes: charging data and discharging data;

[0154] The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval;

[0155] The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range;

[0156] The first measured discharge curve, the second measured discharge curve, the first measured charging curve and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct the measured characteristic matrix of battery pack charging and discharging.

[0157] The SOH correction value calculation module 203 is used to obtain a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtain the SOH correction value based on the difference matrix.

[0158] In this embodiment, the SOH correction value calculation module 203 includes: a difference matrix acquisition unit;

[0159] The difference matrix acquisition unit is used to extract the measured feature segment curve of the measured feature matrix and the measured feature matrix corresponding to the measured feature segment curve;

[0160] According to the characteristic segment curve and the characteristic matrix corresponding to the characteristic segment curve, extract the standard characteristic segment curve of the standard characteristic matrix and the standard characteristic matrix corresponding to the standard characteristic segment curve;

[0161] A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

[0162] In this embodiment, the SOH correction value calculation module 203 includes: an SOH correction value calculation unit;

[0163] The SOH correction value calculation unit is used to screen the minimum value of the difference matrix and obtain the SOH data set;

[0164] The SOH data set is filtered to remove outliers in the SOH data set, and the removed outliers are filled according to the sliding algorithm to obtain the corrected SOH data set;

[0165] Calculate the average of the corrected SOH data set to obtain the corrected SOH value.

[0166] The SOH correction module 204 is used to obtain the cumulative charge and discharge data of the battery pack, calculate the SOH calculated value of the battery pack according to the cumulative charge and discharge data of the battery pack, and correct the SOH calculated value according to the SOH correction value.

[0167] In this embodiment, the SOH correction module 204 includes: a SOH correction module unit;

[0168] The SOH correction unit is used to obtain the cumulative charge and discharge data of the battery pack;

[0169] Obtain the SOH calculation value of the battery pack according to the preset algorithm;

[0170] The SOH difference between the SOH calculated value and the SOH corrected value is calculated, and the SOH calculated value is corrected according to the SOH difference and a preset correction factor.

[0171] This embodiment performs a cycle life test on the cells in the battery pack, and fits the charge and discharge cycle life curve according to a preset current range to obtain a standard characteristic matrix of the battery pack charge and discharge; then, by collecting the real-time charge and discharge data of the battery pack, the real-time charge and discharge data is divided by current range and preset temperature range to construct a measured characteristic matrix of the battery pack charge and discharge, and then the SOH correction value is determined by the standard characteristic matrix and the measured characteristic matrix, and the SOH calculated value is corrected by the SOH correction value. This embodiment makes up for the poor accuracy of the SOH algorithm commonly used in the prior art by comparing the standard charge and discharge data of the cells in the battery pack with their own charge and discharge capabilities during actual use, and combining it with the battery pack SOH calculation algorithm. From the two perspectives of the standard charge and discharge data and the actual charge and discharge data of the battery pack, the accuracy of the correction of the SOH value is further improved, so that the SOH value is closer to the actual life value of the battery pack itself, and the accuracy of the SOH value of the battery pack is improved.

[0172] In summary, the embodiment of the present invention performs a cycle life test on the battery cells in the battery pack, and fits the charge and discharge cycle life curve according to a preset current range to obtain a standard characteristic matrix of the battery pack charge and discharge; then, by collecting the real-time charge and discharge data of the battery pack, the real-time charge and discharge data is divided by the current range and the preset temperature range to construct a measured characteristic matrix of the battery pack charge and discharge, and then the SOH correction value is determined by the standard characteristic matrix and the measured characteristic matrix, and the correction of the SOH calculated value is achieved through the SOH correction value. The embodiment of the present invention makes up for the poor accuracy of the SOH algorithm commonly used in the prior art by comparing the standard charge and discharge data of the battery cells in the battery pack with their own charge and discharge capabilities during actual use, and combines it with the battery pack SOH calculation algorithm. Through the two perspectives of the standard charge and discharge data and the actual charge and discharge data of the battery pack, the correction accuracy of the SOH value is further improved, so that the SOH value is closer to the actual life value of the battery pack itself, and the accuracy of the SOH value of the battery pack is improved.

[0173] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for correcting SOH of a battery pack, characterized in that: Applicable to battery packs including cells, including: Performing a cycle life test on the battery cell to obtain a plurality of charge-discharge cycle life curves; fitting the plurality of charge-discharge cycle life curves according to a preset current range to obtain a standard characteristic matrix of battery pack charge and discharge; Collecting real-time charge and discharge data of the battery pack, dividing the real-time charge and discharge data according to the preset current range and the preset temperature range, and constructing a measured characteristic matrix of the charge and discharge of the battery pack; Obtaining a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtaining a SOH correction value based on the difference matrix; The accumulated charge and discharge data of the battery pack are acquired, and a SOH calculated value of the battery pack is calculated according to the accumulated charge and discharge data of the battery pack, and the SOH calculated value is corrected according to the SOH correction value.

2. A method for correcting the SOH of a battery pack as claimed in claim 1, characterized in that: The battery cell is subjected to a cycle life test to obtain a plurality of charge-discharge cycle life curves; Fitting the plurality of charge and discharge cycle life curves according to a preset current interval to obtain a standard characteristic matrix of battery pack charge and discharge, specifically comprising: the preset current interval comprises: a first current interval and a second current interval; Performing a cycle life test on the battery cell to obtain a plurality of charge-discharge cycle life curves in a preset SOH range; Fitting the plurality of charge-discharge cycle life curves to obtain expansions corresponding to the plurality of charge-discharge cycle life curves and data matrices corresponding to the expansions; Analyzing the expansions corresponding to the plurality of charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the plurality of charge-discharge cycle life curves; According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval; A standard characteristic matrix for charging and discharging a battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

3. A method for correcting SOH of a battery pack as claimed in claim 2, characterized in that: The collecting of real-time charge and discharge data of the battery pack, dividing the real-time charge and discharge data according to the preset current range and the preset temperature range, and constructing a measured characteristic matrix of the charge and discharge of the battery pack specifically includes: Collecting real-time charge and discharge data of the battery pack, wherein the real-time charge and discharge data includes: charging data and discharging data; The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval; The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range; The first measured discharge curve, the second measured discharge curve, the first measured charging curve, and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct a measured characteristic matrix of battery pack charging and discharging.

4. A method for correcting SOH of a battery pack as claimed in claim 3, characterized in that: The obtaining of the difference matrix according to the standard feature matrix and the measured feature matrix specifically includes: Extracting a measured feature segment curve of the measured feature matrix and a measured feature matrix corresponding to the measured feature segment curve; Extracting the standard feature segment curve of the standard feature matrix and the standard feature matrix corresponding to the standard feature segment curve according to the feature segment curve and the feature matrix corresponding to the feature segment curve; A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

5. A method for correcting SOH of a battery pack as claimed in claim 4, characterized in that: The obtaining of the SOH correction value based on the difference matrix specifically includes: Screening the minimum value of the difference matrix to obtain the SOH data set; Performing filtering processing on the SOH data set to remove outliers in the SOH data set, and filling the removed outliers according to a sliding algorithm to obtain a corrected SOH data set; Calculate the average of the corrected SOH data set to obtain the corrected SOH value.

6. A method for correcting SOH of a battery pack as claimed in claim 1 or 5, characterized in that: The acquiring of the cumulative charge and discharge data of the battery pack, calculating the SOH calculated value of the battery pack according to the cumulative charge and discharge data of the battery pack, and correcting the SOH calculated value according to the SOH correction value specifically includes: Obtain the cumulative charge and discharge data of the battery pack; Obtain the SOH calculation value of the battery pack according to the preset algorithm; A SOH difference between the SOH calculated value and the SOH corrected value is calculated, and the SOH calculated value is corrected according to the SOH difference and a preset correction factor.

7. A SOH correction device for a battery pack, characterized in that: Applicable to battery packs including battery cells, including: standard characteristic matrix calculation module, measured characteristic matrix calculation module, SOH correction value calculation module and SOH correction module; The standard characteristic matrix calculation module is used to perform a cycle life test on the battery cell to obtain a plurality of charge and discharge cycle life curves; the plurality of charge and discharge cycle life curves are fitted according to a preset current range to obtain a standard characteristic matrix of battery pack charge and discharge; The measured characteristic matrix calculation module is used to collect real-time charge and discharge data of the battery pack, divide the real-time charge and discharge data according to the preset current range and the preset temperature range, and construct a measured characteristic matrix of the charge and discharge of the battery pack; The SOH correction value calculation module is used to obtain a difference matrix according to the standard characteristic matrix and the measured characteristic matrix, and obtain the SOH correction value based on the difference matrix; The SOH correction module is used to obtain the cumulative charge and discharge data of the battery pack, calculate the SOH calculated value of the battery pack according to the cumulative charge and discharge data of the battery pack, and correct the SOH calculated value according to the SOH correction value.

8. A battery pack SOH correction device as claimed in claim 7, characterized in that: The standard characteristic matrix calculation module includes: a standard characteristic matrix calculation unit; In the standard characteristic matrix calculation unit, the preset current interval includes: a first current interval and a second current interval; The standard characteristic matrix calculation unit is used to perform a cycle life test on the battery cell to obtain a plurality of charge and discharge cycle life curves in a preset SOH range; Fitting the plurality of charge-discharge cycle life curves to obtain expansions corresponding to the plurality of charge-discharge cycle life curves and data matrices corresponding to the expansions; Analyzing the expansions corresponding to the plurality of charge-discharge cycle life curves and the data matrices corresponding to the expansions to obtain characteristic segment curves in the plurality of charge-discharge cycle life curves; According to the first current interval and the second current interval, the characteristic segment curve is fitted by Taylor expansion to obtain a first charging characteristic segment matrix and a first discharging characteristic segment matrix corresponding to the first current interval, and a second charging characteristic segment matrix and a second discharging characteristic segment matrix corresponding to the second current interval; A standard characteristic matrix for charging and discharging a battery pack is determined according to the first charging characteristic segment matrix, the first discharging characteristic segment matrix, the second charging characteristic segment matrix, and the second discharging characteristic segment matrix.

9. A battery pack SOH correction device as claimed in claim 8, characterized in that: The measured characteristic matrix calculation module includes: a measured characteristic matrix calculation unit; The measured characteristic matrix calculation unit is used to collect real-time charge and discharge data of the battery pack, and the real-time charge and discharge data includes: charging data and discharging data; The discharge data is screened according to a preset temperature interval, a first current interval, and a second current interval to obtain a first measured discharge curve in the first current interval and a second measured discharge curve in the second current interval; The charging data is screened according to a preset temperature range, a first current range, and a second current range to obtain a first measured charging curve in the first current range and a second measured charging curve in the second current range; The first measured discharge curve, the second measured discharge curve, the first measured charging curve, and the second measured charging curve are fitted respectively by Taylor sixth-order expansion to obtain the corresponding first measured discharge characteristic segment curve and the first discharge characteristic matrix, the second measured discharge characteristic segment curve and the second discharge characteristic matrix, the first measured charging characteristic segment curve and the first charging characteristic matrix, and the second measured charging characteristic segment curve and the second charging characteristic matrix, so as to construct a measured characteristic matrix of battery pack charging and discharging.

10. The SOH correction device for a battery pack as claimed in claim 8, characterized in that: The SOH correction value calculation module includes: a difference matrix calculation unit; The difference matrix calculation unit is used to extract the measured feature segment curve of the measured feature matrix and the measured feature matrix corresponding to the measured feature segment curve; Extracting the standard feature segment curve of the standard feature matrix and the standard feature matrix corresponding to the standard feature segment curve according to the feature segment curve and the feature matrix corresponding to the feature segment curve; A difference matrix is ​​obtained based on the measured characteristic segment curve, the measured characteristic matrix, the standard characteristic segment curve and the standard characteristic matrix.

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