Battery system power limit estimation methods, battery management systems and electrical equipment

Abstract

The present application discloses a method for estimating the power limit of a battery system, a battery management system, and an electrical device. The target model is determined based on the functional relationship between the DC internal resistance and the discharge current of the battery system, and the voltage division principle of the battery internal resistance; the target model is solved to determine the maximum discharge current of the battery system at the limit voltage; the product of the maximum discharge current of the battery system at the limit voltage and the discharge limit voltage at the specified SOC of the battery system is determined as the power limit of the battery system. The present application is directly based on the pulse power test results at the level of the entire battery system, and combined with the influencing factors of the discharge current size and the DC internal resistance of the battery cell, to infer the battery power limit capability at the level of the entire battery system, thus saving the time of battery cell testing.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries, and in particular to a method, system and electrical equipment for estimating the limit power of a battery system. Background Art

[0002] The current system power calculation method mainly relies on the power test of single battery cells, and the power conversion from battery cells to whole packs still mainly relies on empirical coefficients. Therefore, the power of the battery system finally obtained is limited by the accuracy of the battery cell test and the empirical coefficients are often unable to characterize the maximum power performance of the battery system. In addition, in addition to the power test at the battery cell level, the battery system level test verification is also required, which causes a certain degree of waste of testing resources. Summary of the invention

[0003] The purpose of this application is to provide a method for estimating the limit power of a battery system, a battery management system, and an electrical device to save time for battery cell testing.

[0004] In order to achieve the above technical effects, this application adopts the following technical solutions.

[0005] In a first aspect, the present application provides a method for estimating a limit power of a battery system, comprising:

[0006] Determine the target model based on the functional relationship between the DC internal resistance and discharge current of the battery system and the voltage division principle of the battery internal resistance;

[0007] Solving the target model to determine the maximum discharge current of the battery system when the battery system reaches the limit voltage;

[0008] The product of the maximum discharge current of the battery system when it reaches the limit voltage and the discharge limit voltage of the battery system at the specified SOC is determined as the limit power of the battery system.

[0009] In some embodiments, the target model represents the relationship between the discharge limit voltage of the battery system at a specified SOC, the open circuit voltage of the battery system at a specified SOC, the DC internal resistance of the battery system, and the discharge current.

[0010] In some embodiments, the target model is represented as follows:

[0011] OPV-U min =F(I)·I;

[0012] Wherein, OPV is the open circuit voltage of the battery system at a specified SOC, U min The discharge limit voltage under the specified SOC is specified for the battery system, F(I) is the functional relationship between the DC internal resistance and the discharge current of the battery system, and I is the discharge current.

[0013] In some embodiments, the functional relationship F(I) between the DC internal resistance and the discharge current of the battery system is expressed as follows:

[0014] F(I)=Pack DCIR ;

[0015] Pack DCIR =K1I+B1(I<I s ), where K1<0;

[0016] Pack DCIR =K2I+B2(I>I s ), where K2>0;

[0017] Among them, I s is the discharge current corresponding to the minimum DC internal resistance of the battery; K1 is the current less than I s When the internal resistance decreases with the increase of discharge current, K1 is the derating factor of the current greater than I s When the discharge current increases, the internal resistance increases with the growth coefficient; B1 is the first constant term; B2 is the second constant term.

[0018] In some embodiments, the method further comprises:

[0019] Based on the limit power of the battery system, an SOC deviation correction is performed to obtain a first limit power correction value, where the first limit power correction value is expressed as follows:

[0020] Power max2 (T)=Power max1 *(1-Y);

[0021] Among them, Power max1 is the limit power of the battery system, Y is the SOC accuracy deviation value, T is the current temperature, Power max2 () is the expression function of the first limit power correction value.

[0022] In some embodiments, the method for determining the SOC accuracy deviation value Y is as follows:

[0023] According to the temperature and the SOC corresponding to it, a SOC accuracy deviation curve is determined by fitting, and the SOC accuracy deviation value is determined according to the SOC accuracy deviation curve.

[0024] In some embodiments, the method further comprises:

[0025] Based on the first limit power correction value, temperature correction is performed to obtain a second limit power correction value, and the second limit power correction value is expressed as follows:

[0026] Power max3=Power max2 (TZ), T1≤T≤T k ;

[0027] Power max3 =Power max2 (T+Z), T k <T≤T4;

[0028] Among them, T1 is the lower limit of the battery system operating temperature, T4 is the upper limit of the battery system operating temperature, T k is the temperature setting value, and Z is the temperature deviation value at the current temperature T.

[0029] In some embodiments, the method for determining the functional relationship between the DC internal resistance and the discharge current of the battery system is as follows:

[0030] Setting the discharge time of the battery system; adjusting the battery system to a specified SOC;

[0031] The battery system is discharged in sequence according to a plurality of set discharge currents, and the voltage of the corresponding battery system is determined after the discharge time; the DC internal resistance under each of the set discharge currents is calculated according to each of the set discharge currents and the voltage of the corresponding battery system;

[0032] According to each of the set discharge currents and the DC internal resistance under each of the set discharge currents, a function of the discharge current and the internal resistance of the battery system is fitted.

[0033] In a second aspect, the present application further provides a battery management system, including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the above-mentioned limit power estimation method when executing the computer program.

[0034] In a third aspect, the present application provides an electrical device, including the battery management system as described above.

[0035] The beneficial effects of the present application are as follows: the present application provides a method for estimating the power limit of a battery system, a battery management system, and electrical equipment. The present application is directly based on the pulse power test results at the level of the entire battery system, and combined with the influencing factors of the discharge current size and the DC internal resistance of the battery cell, to infer the battery power limit capability at the level of the entire battery system, thus saving the time for battery cell testing. The present application also takes into account the correction of the SOC (State Of Charge) deviation and the correction of the temperature field distribution deviation in the battery system. At the same time, the limit power after the SOC deviation correction and the temperature field correction can better characterize the actual limit power performance of the battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present application in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes and are used to help understand the present application. They do not specifically limit the shapes and proportional dimensions of the components of the present application. Under the guidance of the present application, those skilled in the art can select various possible shapes and proportional dimensions to implement the present application according to specific circumstances. In the drawings:

[0037] Figure 1 A schematic diagram of a process flow of a method for estimating the limit power of a battery system provided in one embodiment of the present application;

[0038] Figure 2 A schematic diagram of a flow chart of a method for estimating the limit power of a battery system provided in another embodiment of the present application;

[0039] Figure 3 This is a schematic diagram of a fitting curve of the DC internal resistance and discharge current function of a battery system in one embodiment of the present application;

[0040] Figure 4 This is a simplified model schematic diagram of a DC internal resistance and discharge current function fitting curve of a battery system in one embodiment of the present application;

[0041] Figure 5 This is a schematic diagram of a SOC accuracy deviation curve of a battery system in one embodiment of the present application;

[0042] Figure 6 This is a schematic diagram of an SOC accuracy deviation curve after temperature correction of the battery system limit power in one embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0044] A battery system refers to an electric energy supply system consisting of one or more battery packs connected in series or parallel and equipped with a complete battery management system.

[0045] The power of a battery system is the amount of energy that the battery system can output per unit time.

[0046] The battery system's limit power, also known as SOP (State Of Powder), refers to the maximum discharge power that the battery system can provide at the next moment and under continuous high current. Accurate estimation of SOP can maximize battery utilization efficiency.

[0047] For example, for new energy vehicle power batteries, the ultimate power of its battery system, as an important performance indicator, plays a vital role in the acceleration performance of the entire vehicle.

[0048] The calculation method of the power of the battery system may include:

[0049] The first step is to apply a certain discharge current to the single cell at a specific state of charge, obtain the cell voltage and multiply the voltage and current to obtain the power of the single cell;

[0050] The second step is to calculate the cumulative power based on the number of battery systems in series and parallel;

[0051] The third step is to accumulate power by applying a certain discount coefficient (0.8 to 0.95) based on the internal resistance of the system's high-voltage electrical connectors and the SOC estimation deviation to obtain the power of the entire battery system. Finally, actual measurement is used to verify whether the power of the entire battery system meets customer requirements.

[0052] The power calculation method of this battery system mainly relies on the power test of single battery cells. The final power of the battery system is limited by the accuracy of the battery cell test and often cannot represent the maximum power performance of the battery system. In addition, in addition to the power test at the battery cell level, battery system level test verification is also required, which causes a waste of testing resources to a certain extent.

[0053] The method for estimating the ultimate power performance of a battery system provided in the embodiment of the present application is directly based on the pulse power test results at the level of the entire battery system, and is combined with the influencing factors of the discharge current size and the DC internal resistance of the battery cell to infer the battery power ultimate capability at the level of the entire battery system, thereby saving time for battery cell testing.

[0054] The method for estimating the limit power of a battery system provided in an embodiment of the present application also takes into account the correction of the SOC (State Of Charge) deviation and the temperature field distribution deviation in the battery system. At the same time, the limit power after the SOC deviation correction and the temperature field correction can better represent the actual limit power performance of the battery system.

[0055] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, in the description of the present application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels, and no numerical requirements are imposed or an order is established.

[0056] In some embodiments, Figure 1 As shown, the method for estimating the limiting power of a battery system includes:

[0057] Determine the target model based on the functional relationship between the DC internal resistance and discharge current of the battery system and the voltage division principle of the battery internal resistance;

[0058] Solve the target model to determine the maximum discharge current when the battery system reaches the limit voltage;

[0059] The product of the maximum discharge current when the battery system reaches the limit voltage and the discharge limit voltage at the specified SOC of the battery system is determined as the limit power of the battery system.

[0060] In some embodiments, the target model represents the relationship between the discharge limit voltage of the battery system at a specified SOC, the open circuit voltage of the battery system at a specified SOC, the DC internal resistance of the battery system, and the discharge current.

[0061] The discharge limit voltage under a specified SOC comprehensively considers the operating voltage range of the battery system. The open circuit voltage of the battery system comprehensively considers the differences in battery cell consistency. The actual voltage value is more realistic than the open circuit voltage of the battery cell. The DC resistance of the battery system comprehensively considers the internal resistance of the battery cell and the internal resistance of electrical components and welding. The discharge current comprehensively considers the actual driving conditions of the vehicle. The relationship between the voltage, current and internal resistance of the battery system obtained in this way can better represent the actual usage scenario.

[0062] In some embodiments, determining the functional relationship between the DC internal resistance of the battery system and the discharge current includes:

[0063] Set the discharge time of the battery system to N (N is generally 2, 10, 30, 60, 100, etc. according to customer requirements) seconds; adjust the battery system to the specified SOC;

[0064] The battery system discharges according to a first set discharge current, records a corresponding first battery system voltage after a set discharge time, and calculates a first DC resistance under the first set current according to the first set discharge current and the first battery system voltage;

[0065] The battery system discharges according to a second set discharge current, records a corresponding second battery system voltage after a set discharge time, and calculates a second DC resistance under the second set current according to the second set discharge current and the second battery system voltage;

[0066] The battery system discharges according to a third set discharge current, records a corresponding third battery system voltage after a set discharge time, and calculates a third DC resistance under the third set current according to the third set discharge current and the third battery system voltage;

[0067] A function curve of the DC internal resistance and the discharge current of the battery system is fitted according to the first set discharge current, the second set discharge current, the third set discharge current and the corresponding first DC resistance, the second DC resistance and the third DC resistance respectively.

[0068] In a specific embodiment, the battery system voltage U is recorded after discharging at the current I1 for N seconds. end1 , calculate the DC internal resistance corresponding to the I1 current Record the voltage U of the battery system after discharging at 2I1 current for N seconds end2 , calculate the DC internal resistance corresponding to the current of 21 After discharging at 5I1 current for N seconds, record the voltage U of the battery system end3 , calculate the DC internal resistance corresponding to the 51 current The function of current and battery system internal resistance is fitted according to the DC internal resistance at different currents.

[0069] The DC internal resistance of the battery is mainly divided into ohmic internal resistance, electrochemical polarization internal resistance and concentration polarization internal resistance. The ohmic internal resistance is mainly the contact resistance of the battery cell and various electrical components, which is basically not affected by the current; the electrochemical polarization internal resistance and the concentration polarization internal resistance are the internal resistances caused by battery polarization. When the current is small, the polarization internal resistance is mainly controlled by electrochemical polarization. At this time, as the current increases, the electrochemical polarization internal resistance decreases, and the battery DC internal resistance decreases. However, when the current increases to a certain extent, the DC internal resistance is affected by the concentration polarization. As the current increases, the concentration polarization internal resistance increases, and the overall DC internal resistance increases. Based on the above characteristics of the battery system with the change of DC resistance with current and the measured DC internal resistance values ​​of I1, 2I1, and 5I1, Pack DCIR1 、Pack DCIR2 、Pack DCIR3 The function curve of discharge current and internal resistance is as follows: Figure 3 shown.

[0070] in accordance with Figure 3 The function curve shown simplifies the internal resistance and current curves. Figure 4 shown.

[0071] Based on the simplified linear model, the functional relationship between the DC internal resistance and current of the battery system is obtained:

[0072] Pack DCIR =K1I+B1(I<I s ), where K1<0 (I);

[0073] Pack DCIR =K2I+B2(I>I s ), where K2>0 (II);

[0074] I s : The current corresponding to the minimum DC internal resistance of the battery;

[0075] K1: Current is less than I s When the internal resistance decreases with the increase of current, the derating factor;

[0076] K1: Current is greater than I s When , the internal resistance increases with the increase of current;

[0077] B1: Theoretical value of battery internal resistance when the current is 0;

[0078] B2: Based on I s As well as 5I1 and the corresponding battery system DC internal resistance value fitting, it has no actual physical meaning.

[0079] The above (I) and (II) are combined into: Pack DCIR =F(I) (III);

[0080] Define the discharge limit voltage of the battery system at a specified SOC as U min , then according to the battery internal resistance voltage division principle:

[0081] OPV-U min =Pack DCIR I (IV);

[0082] Substitute (III) into (IV) to obtain: OPV-U min =F(I)·I;

[0083] Wherein, OPV is the open circuit voltage of the battery system at a specified SOC. In a specific implementation, the battery system can be adjusted to a specified SOC (State Of Charge), and the open circuit voltage OPV (Open Pack Voltage) of the battery system at the specified SOC is recorded.

[0084] From this, we can get the maximum current I when the battery system reaches the limit voltage max , then the theoretical limit power of the battery system is:

[0085] Power max1 =I max *U min (V);

[0086] In the actual battery system, there is a deviation between the SOC actually calculated by the actual battery management system BMS (Battery Management System) and the actual value, and the deviation amount at each temperature is different. Generally, the SOC accuracy deviation at low temperature and high temperature is large. Based on the SOC accuracy laboratory test results, the SOC deviation curve is established as follows: Figure 5 shown.

[0087] Define Y1 as the SOC accuracy deviation value at temperature T1, T1 is defined as the lower limit of the operating temperature of the battery system, Y2 is the SOC accuracy deviation value at temperature T2, Y3 is the SOC accuracy deviation value at temperature T3, Y4 is the SOC accuracy deviation value at temperature T4, and T4 is defined as the upper limit of the operating temperature of the battery system.

[0088] In some embodiments, based on the above embodiments, based on the battery system theoretical limit power Power max1 Perform SOC deviation correction to obtain the first limit power correction value Power max2 (T), expressed as:

[0089] Power max2 (T)=Power max1 *(1-Y) (VI);

[0090] Where Y is the SOC accuracy deviation value.

[0091] The battery's SOC (State-of-Charge) refers to the state of the battery's remaining power. The remaining power of the battery is generally read as a percentage. For convenience, the battery's SOC is usually expressed as follows:

[0092] SOC=Q c / Q n 100%;

[0093] Where Q c Refers to the remaining available battery power at a certain moment, Q n Refers to the rated capacity of the battery.

[0094] In a specific implementation, the SOC accuracy deviation value at a specific temperature may be measured by the following steps: a) charging the battery system to a full charge state using the charging specification used in the available capacity test;

[0095] b) Leave to stand for not less than 30 minutes or the prescribed shelf time (not more than 60 minutes);

[0096] c) Discharge at 1Q0(A) for 12min;

[0097] d) Leave it to stand for not less than 30 minutes or the prescribed shelf time (not more than 60 minutes);

[0098] e) Adopt specific operating conditions (refer to normative standards or determined by negotiation) and cycle N times, where N is the maximum number that makes the actual SOC close to 30%.

[0099] f) Leave to stand for not less than 30 minutes or the prescribed shelf time (not more than 60 minutes);

[0100] g) Charge the battery system to 80% using the charging specifications used during the available capacity test;

[0101] h) Leave to stand for not less than 30 minutes or the shelf time specified by the manufacturer (not more than 60 minutes);

[0102] i) Press e) to h) for 10 cycles;

[0103] j) Record the SOC_BMS value reported by the battery management system BMS;

[0104] k) Discharge the battery system according to the discharge specification used in the available capacity test, record the discharge amount Q1, and calculate the SOC_true value as follows:

[0105] SOC_true value = Q1 / Q0·100%;

[0106] SOC accuracy deviation value = |SOC_true value - SOC_BMS value|.

[0107] In some embodiments, based on the above embodiments, such as Figure 2 As shown, the limiting power estimation method of the battery system also includes power temperature correction.

[0108] A temperature sensor is generally arranged in the battery system to collect the battery temperature. However, there is a deviation between the actual temperature and the temperature collected by the temperature sensor. This deviation is mainly caused by the sensor accuracy, software algorithm accuracy and the distribution position of the temperature sensor. Based on this, the first limit power correction value Power max2 (T) Perform temperature correction to obtain the second limit power correction value Power max3 .

[0109] First, the temperature deviation value Z of the battery system is obtained in the laboratory, and the power-temperature curve under a certain SOC is established after temperature correction. Figure 6 shown.

[0110] Generally, at low temperatures, the battery has a larger internal resistance, greater polarization, and lower power. At high temperatures, considering the risk of overheating and battery aging, the battery power will be reduced compared to normal temperature. P1 is defined as the temperature deviation value at temperature T1, T1 is defined as the lower limit of the operating temperature of the battery system, P2 is the temperature deviation value at temperature T2, P3 is the temperature deviation value at temperature T3, P4 is the temperature deviation value at temperature T4, and T4 is defined as the upper limit of the operating temperature of the battery system.

[0111] The temperature deviation value refers to the absolute value of the difference between the temperature value collected by the BMS system and the actual temperature value of the battery cell actually tested. Optionally, temperature sensors are arranged at different positions of the battery cell to test the actual temperature value of the battery cell according to specific working conditions.

[0112] Optionally, T2 may be the normal operating temperature of the battery system (generally room temperature), and T3 may be the power derating point temperature determined by the battery system due to aging life and vehicle thermal management strategy.

[0113] Based on the temperature deviation value Z measured in the laboratory and the power temperature curve under the above-mentioned specific SOC, the first limit power correction value Power max2 (T) Temperature correction:

[0114] Power max3 =Power max2 (TZ), T1≤T≤T k (VII)

[0115] Power max3 =Power max2 (T+Z), T k <7≤T4 (VIII)

[0116] In a specific embodiment, the temperature setting value T k Can be set between T2 and T3.

[0117] The method for estimating the limit power of a battery system provided in the present application combines the influencing factors of the current size and the DC internal resistance of the battery cell, and obtains the limit power test and calculation of the battery system without relying on the battery cell test, thus saving the time of the battery cell test.

[0118] At the same time, taking into account the SOC deviation correction and temperature field distribution deviation correction in the battery system, the battery power limit capability at the entire battery system level is calculated. At the same time, the limit power after SOC deviation correction and temperature field correction can better represent the actual limit power performance of the battery system.

[0119] In some embodiments, the present application also provides a battery management system (Battery Management System, BMS), including a memory and a processor, the memory stores a computer program that can be executed on the processor, and the processor implements the above-mentioned limit power estimation method when executing the computer program.

[0120] Memory may include non-volatile storage medium, internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be realized by WIFI, mobile cellular network, NFC (near field communication)) or other technologies. When the computer program is executed by a processor, a SOP estimation method for a power battery pack is realized. The display screen of the computer device can be a liquid crystal display or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, a trackball or a touchpad arranged on the computer device housing, or an external keyboard, a touchpad or a mouse, etc.

[0121] In some embodiments, the present application further provides an electric device, including the above battery management system. In some embodiments, the electric device of the present application can be, but is not limited to, a portable electronic device such as a mobile phone, a tablet computer, a laptop computer, an e-reader, etc., and can also be a drone, a backup power supply, an electric car, an electric motorcycle, an electric boat, an electric tool, a large household battery, etc.

[0122] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed application subject matter.

Claims

1. A method for estimating the limit power of a battery system, characterized in that: include: Determine the target model based on the functional relationship between the DC internal resistance and discharge current of the battery system and the voltage division principle of the battery internal resistance; Solving the target model to determine the maximum discharge current of the battery system when the battery system reaches the limit voltage; The product of the maximum discharge current and the discharge limit voltage at the specified SOC of the battery system is determined as the limit power of the battery system; The functional relationship F(I) between the DC internal resistance and the discharge current of the battery system is expressed as follows: F(I)=Pack DCIR ; Pack DCIR =K1I+B1(I<I s ), where K1<0; Pack DCIR =K2I+B2(I>I s ), where K2>0; Among them, I s is the discharge current corresponding to the minimum DC internal resistance of the battery; K1 is the current less than I s When the internal resistance decreases with the increase of discharge current, K1 is the derating factor of the current greater than I s When the internal resistance increases with the discharge current, the growth coefficient increases; B1 is the first constant term; B2 is the second constant term; The target model is expressed as follows: OPV-U min =F(I)·I; Wherein, OPV is the open circuit voltage of the battery system at a specified SOC, U min The discharge limit voltage under the specified SOC is specified for the battery system, F(I) is the functional relationship between the DC internal resistance and the discharge current of the battery system, and I is the discharge current.

2. The method for estimating the limit power of a battery system according to claim 1, characterized in that: The target model represents the relationship between the discharge limit voltage of the battery system at a specified SOC, the open circuit voltage of the battery system at a specified SOC, the DC internal resistance of the battery system, and the discharge current.

3. The method for estimating the limit power of a battery system according to claim 1, characterized in that: The method further comprises: Based on the limit power of the battery system, an SOC deviation correction is performed to obtain a first limit power correction value, where the first limit power correction value is expressed as follows: Power max2 (T)=Power max1 *(1-Y); Among them, Power max1 is the limit power of the battery system, Y is the SOC accuracy deviation value, T is the current temperature, Power max2 () is the expression function of the first limit power correction value.

4. The method for estimating the limit power of a battery system according to claim 3, characterized in that: The method for determining the SOC accuracy deviation value is as follows: According to the temperature and its corresponding SOC, the SOC accuracy deviation curve is determined by fitting; The SOC accuracy deviation value is determined according to the SOC accuracy deviation curve.

5. The method for estimating the limit power of a battery system according to claim 3, characterized in that: The method further comprises: Based on the first limit power correction value, temperature correction is performed to obtain a second limit power correction value, and the second limit power correction value is expressed as follows: Power max3 =Power max2 (T-Z),T1≤T≤T k ; Power max3 =Power max2 (T+Z),T k <T≤T4; Among them, T1 is the lower limit of the battery system operating temperature, T4 is the upper limit of the battery system operating temperature, T k is the temperature setting value, and Z is the temperature deviation value at the current temperature.

6. The method for estimating the limit power of a battery system according to claim 1, characterized in that: The method for determining the functional relationship between the DC internal resistance and the discharge current of the battery system is as follows: Setting the discharge time of the battery system; adjusting the battery system to a specified SOC; The battery system is discharged in sequence according to a plurality of set discharge currents, and the voltage of the corresponding battery system is determined after the discharge time; the DC internal resistance under each of the set discharge currents is calculated according to each of the set discharge currents and the voltage of the corresponding battery system; According to each of the set discharge currents and the DC internal resistance under each of the set discharge currents, a function of the discharge current and the internal resistance of the battery system is fitted.

7. A battery management system, characterized in that: The invention comprises a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the limit power estimation method according to any one of claims 1 to 6 when executing the computer program.

8. An electrical device, characterized in that: Comprising the battery management system as claimed in claim 7.

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