Capacity estimation method of secondary battery, battery management system and electric equipment

Abstract

The embodiment of the invention provides a capacity estimation method of a secondary battery, a battery management system and electric equipment, and the capacity estimation method provided by the embodiment of the invention only needs to calculate the process capacity between two capacity state recognition points to obtain a first estimated capacity and a corresponding first weight value. And then adjusting the second weight values corresponding to the plurality of second estimated capacities determined previously, namely dynamically adjusting the weight values for the estimated capacities determined in each process, and further participating in solving the weighted average value, thereby obtaining the actual capacity of the battery, and being capable of improving the capacity of the battery under the condition of not increasing additional communication means. According to the method, the capacity of the battery cluster which does not meet the conventional full charge and discharge calibration capacity is calculated, and meanwhile, the difference between the SOC calculation capacity and the actual capacity is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of battery management, and in particular to a capacity estimation method for a secondary battery, a battery management system, and an electrical device. Background Art

[0002] There are a huge number of energy storage batteries such as lithium iron phosphate batteries in the energy storage system, which are usually connected in series and parallel to meet the needs of various application scenarios. Among them, the energy storage batteries are generally connected in series and then managed by the cluster management control unit (BCMU). After each cluster is connected in parallel to form a stack, it is managed by the stack management control unit (BSMU). The stack is generally composed of multiple battery clusters connected in parallel. The parallel connection of different battery clusters can expand the system capacity.

[0003] However, both the series battery pack and the parallel battery cluster will cause the overall capacity to decrease due to uneven capacity, or the actual capacity of the battery system will increase after the balancing algorithm is applied. After a period of use, the changes in the overall capacity due to various factors will affect the accuracy of the SOC algorithm. SOC intuitively reflects the current nuclear power status of the battery pack, and a good capacity estimation will help improve the accuracy of the SOC algorithm.

[0004] In the prior art, battery management systems usually estimate the capacity by fully charging and discharging the battery system. This process is prone to failure to meet the nuclear capacity conditions due to factors such as user usage habits and application scenarios, resulting in long-term uncalibrated capacity, which in turn affects the accuracy of the SOC algorithm. Summary of the invention

[0005] The technical problem to be solved by the present application is to provide a capacity estimation method for a secondary battery, a battery management system and an electrical device, so as to solve the problem that the existing capacity calibration conditions are difficult to meet, resulting in the inability to timely estimate the capacity of the secondary battery.

[0006] In order to solve the above problems, the present application is implemented through the following technical solutions:

[0007] The present application proposes a method for estimating the capacity of a secondary battery, which includes:

[0008] Identify at least two capacity status identification points during the battery charging and discharging process;

[0009] Recording the process capacity between any two of the capacity state identification points;

[0010] For each of the process capacities, determining a current first estimated capacity of the battery and a first weight value corresponding to the first estimated capacity according to the two capacity state identification points corresponding to the process capacity;

[0011] According to the first weight value corresponding to the first estimated capacity, adjusting the second weight value corresponding to at least one of the plurality of second estimated capacities so that the sum of the second weight values ​​corresponding to the plurality of second estimated capacities and the first weight value corresponding to the first estimated capacity is 1; wherein the second estimated capacity is the estimated capacity of the battery determined before the first estimated capacity;

[0012] The actual capacity of the battery is estimated according to the plurality of second estimated capacities and the adjusted second weight values, and the first estimated capacity and the first weight value.

[0013] Further, in the capacity estimation method, the capacity state identification point includes a charge state identification point, and the process capacity includes a process power; or

[0014] The capacity state identification point includes an energy state identification point, and the process capacity includes process energy.

[0015] Furthermore, in the capacity estimation method, at least two capacity state identification points include a fully charged state of charge point, an empty state of charge point, a deep discharge state of charge point, a charge correction point, and a static state of charge point; the process capacity includes process power;

[0016] Recording the process capacity between two adjacent capacity state identification points includes:

[0017] The first process electric quantity between the full charge state point and the empty charge state point is recorded respectively, the second process electric quantity between the full charge state point and the deep discharge point, between the empty charge state point and the charge correction point, between the charge correction point and the deep discharge point is recorded, and the third process electric quantity between the full charge state point and the static charge state point is recorded.

[0018] Furthermore, in the capacity estimation method, determining the current first estimated capacity of the battery according to the two capacity state identification points corresponding to the process capacity includes:

[0019] When a first process electric quantity between the full charge state of charge point and the empty charge state of charge point is recorded, a first calculated capacity of the battery is determined according to a state of charge difference between the full charge state of charge point and the empty charge state of charge point and the first process electric quantity;

[0020] When a second process electric quantity between the full charge state point and the deep discharge point is recorded, determining a second calculated capacity of the battery according to a state of charge difference between the full charge state point and the deep discharge point and the second process electric quantity;

[0021] When the state of charge difference between the empty state of charge point and the charge correction point and the second process power are recorded, determining the second calculated capacity of the battery according to the state of charge difference between the empty state of charge point and the charge correction point and the second process power;

[0022] When a second process electric quantity between the charge correction point and the deep discharge point is recorded, a second calculated capacity of the battery is determined according to a charge state difference between the charge correction point and the deep discharge point and the second process electric quantity;

[0023] When a third process power between the full charge state point and the rest state point is recorded, a third calculated capacity of the battery is determined according to a state of charge difference between the full charge state point and the rest state point and the third process power.

[0024] Furthermore, in the capacity estimation method, determining a first weight value corresponding to the current first estimated capacity of the battery includes:

[0025] When the first estimated capacity is the first calculated capacity, a first weight value corresponding to the first estimated capacity is (N+4) / (N+M+Q);

[0026] In a case where the first estimated capacity is the second calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q);

[0027] In a case where the first estimated capacity is the third calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q);

[0028] Among them, N, M, and Q are all positive integers.

[0029] Furthermore, in the capacity estimation method, adjusting a second weight value corresponding to at least one of a plurality of second estimated capacities according to a first weight value corresponding to the first estimated capacity includes:

[0030] In a case where the first estimated capacity is the first calculated capacity, all second estimated capacities in the first array are replaced by the first estimated capacity, and the first estimated capacity is filled twice into the second array, and the first estimated capacity is filled twice into the third array; the array lengths of the first array, the second array, and the third array are N, M, and Q, respectively;

[0031] When the first estimated capacity is the second calculated capacity, filling the second array with the first estimated capacity once;

[0032] When the first estimated capacity is the third calculated capacity, filling the third array with the first estimated capacity once;

[0033] According to the quantity of each second estimated capacity in the first array, the second array and the third array, a second weight value corresponding to each second estimated capacity is determined respectively.

[0034] Furthermore, in the capacity estimation method, the values ​​of N, M, and Q are the same.

[0035] Furthermore, in the capacity estimation method, N, M, and Q are all 5.

[0036] Furthermore, the method further comprises:

[0037] After the first capacity state identification point is identified, if the second capacity state identification point is not identified after a preset period of time, the process capacity recorded with the first charge state point as the starting point is discarded, wherein the first capacity state identification point and the second capacity state identification point are two different capacity state identification points.

[0038] Furthermore, in the capacity estimation method, when the capacity identification points include charge state identification points, recording the process capacity between any two of the capacity state identification points includes:

[0039] The current between any two charge state identification points is integrated in ampere-hours to calculate the process power.

[0040] The present application also proposes an electronic device, comprising: a processor, a communication interface, a memory and a communication bus; wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0041] Memory, used to store computer programs;

[0042] The processor is used to implement the steps in the above-mentioned capacity estimation method when executing the program stored in the memory.

[0043] The present application also proposes a computer-readable storage medium on which a computer program is stored, wherein the program, when executed by a processor, implements the steps in the capacity estimation method as described above.

[0044] The present application also proposes a battery management system, which includes the electronic device as described above.

[0045] The present application also proposes an energy storage system, including a secondary battery, wherein the secondary battery serves as an energy storage unit of the energy storage system, wherein the energy storage system also includes the electronic device as described above or includes the battery management system as described above.

[0046] Compared with the prior art, the embodiments of the present application have the following advantages:

[0047] In an embodiment of the present application, a capacity estimation method for a secondary battery is provided, which first identifies at least two capacity state identification points in the battery charging and discharging process and records the process capacity between any two capacity state identification points, and then determines the current first estimated capacity of the battery and the first weight value corresponding to the first estimated capacity according to the two capacity state identification points corresponding to the process power, and adjusts the second weight value corresponding to at least one of the plurality of second estimated capacities determined by the first estimated capacity, so that the sum of the second weight values ​​corresponding to the plurality of second estimated capacities and the first weight value corresponding to the first estimated capacity is 1; then estimates the actual capacity of the battery according to the plurality of second estimated capacities and the adjusted second weight values, as well as the first estimated capacity and the first weight value; wherein, it is only necessary to calculate the process capacity between the two capacity state identification points to obtain the first estimated capacity and the corresponding first weight value, and then adjust the second weight values ​​corresponding to the plurality of second estimated capacities determined previously, so as to dynamically adjust the weight value for the estimated capacity determined by each process, and then participate in obtaining the weighted average value, so as to obtain the actual capacity of the battery, and can realize the capacity calculation of a battery cluster that does not meet the conventional full charge and discharge calibration capacity without adding additional communication means, and at the same time reduce the difference between the SOC calculated capacity and the actual capacity.

[0048] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the topological structure of the existing energy storage system.

[0050] Figure 2 It is a flow chart of a method for estimating the capacity of a secondary battery provided in an embodiment of the present application.

[0051] Figure 3 It is a logical principle diagram of the capacity estimation method provided in the embodiment of the present application.

[0052] Figure 4 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0054] The applicant of this application has found that in the existing energy storage system, the battery management system (BMS), power conversion system (PCS) and energy management system (EMS) are usually managed in collaboration to ensure the safe and reliable operation of the system. Among them, the topology of the existing energy storage system is as follows: Figure 1 As shown, the energy storage unit generally uses multiple battery packs in series to form a cluster, and then the DC side of multiple battery clusters are connected in parallel to the busbar of the PCS.

[0055] Among them, when the battery pack is a lithium battery, due to the inconsistency of lithium batteries, when one of the battery clusters in the system is full, if the other battery clusters in parallel are not full, because the battery clusters are connected in parallel, it is impossible to continue to control the PCS to charge the battery, resulting in a low estimated overall capacity; similarly, when one of the battery clusters in the system is empty and the other battery clusters are not empty, the PCS cannot continue to control the discharge of the battery cluster, which will also result in a low estimated overall capacity; in addition, when the user sets the automatic mode through the EMS, such as charging and discharging within the state of charge (SOC) range of 10% to 90%, the system may not be able to meet the full charge and full discharge, resulting in a long time The battery capacity cannot be updated. The above situations will affect the accuracy of the SOC algorithm.

[0056] Among them, the Battery Management Unit (BMU) is communicated with the battery to collect the charging and discharging current, voltage and other information of each battery; the Battery Cluster Management Unit (BCMU) is communicated with the BMU to summarize the charging and discharging current, voltage and other information of a single battery cluster; the Battery System Management Unit (BSMU) is communicated with the BSMU to summarize the charging and discharging current, voltage and other information of each battery cluster in the entire battery system.

[0057] In order to solve the above problems, the present application provides a method for estimating the capacity of a secondary battery. Figure 2 As shown, it includes steps 101 to 105:

[0058] Step 101: Identify at least two capacity state identification points during the battery charging and discharging process.

[0059] In the above step 101, the charging and discharging process is specifically a charging process or a discharging process, that is, identifying two capacity state identification points passed in sequence during the charging process or the discharging process, that is, the charge or energy state that can more accurately describe the charge state of the battery.

[0060] Optionally, the above-mentioned capacity state identification point can be a relatively accurate nuclear power state value or energy state value, and correspondingly, the process capacity is process electricity and process electric energy respectively.

[0061] Optionally, the capacity state identification point may be a full charge state point, an empty charge state point, a deep discharge state point, a charge correction point and a static charge state point. Among them, the full charge state of charge point is also the state of charge point with a state of charge value of 100%. When the battery pack is fully charged, the state of charge of the battery pack is determined to be 100%; the empty charge state of charge point is also the state of charge point with a state of charge value of 0%. When the battery pack is empty, the state of charge of the battery pack is determined to be 0%; the deep discharge state of charge point is the state of charge point when the SOC value is lower than 15% during discharge and the difference between the voltage value calculated by the pre-calibrated voltage fitting curve and the current cell terminal voltage is less than the set value; the charge correction point is the state of charge point when the state of charge value of the battery pack meets the judgment conditions of 90% SOC and 95% SOC successively during charging, and is determined to be 95%; the static charge point is the state of charge point that is relatively accurate and has a state of charge value lower than 30% identified by the open circuit voltage in the static state. The specific state of charge value of the identification point can be determined by the state of charge point when the difference between the voltage value calculated by the voltage fitting curve in the static state and the current cell terminal open circuit voltage is less than the set value.

[0062] Among them, the state of charge value corresponding to each of the above-mentioned state of charge points is calculated based on the process power determined by integrating the current between the full charge state of charge point and the empty charge state of charge point, combined with the power output or stored in the battery during the current charging and discharging process determined by current integration.

[0063] Step 102: Record the process capacity between any two of the capacity state identification points.

[0064] In the above step 102, the current between the two capacity state identification points is integrated by means of ampere-hour integration or the like, and the amount of electricity output or stored by the battery between the two capacity state identification points is calculated, that is, the process electricity is used as the above process capacity; or the battery operating power is collected and calculated by means of BCMU or the like, and then the current energy state value and the output or stored electric energy are calculated, that is, the process electric energy is used as the above process capacity.

[0065] Step 103: for each of the process capacities, determine a current first estimated capacity of the battery and a first weight value corresponding to the first estimated capacity according to the two capacity state identification points corresponding to the process capacity.

[0066] In the above step 103, the above process power is the power output or stored by the battery between the two capacity state identification points. The process power is divided by the state difference between the two capacity state identification points (that is, the difference between the state values ​​of the two capacity state identification points) to obtain the corresponding initial estimated capacity of the battery as the above first estimated capacity; at the same time, according to the different capacity state identification points, different weights are assigned to the above first estimated capacity according to preset rules to obtain the corresponding first weight value.

[0067] Among them, in the above preset rules, the weight allocated to the first estimated capacity is positively correlated with the accuracy of the capacity state identification point corresponding to the first estimated capacity.

[0068] Step 104. According to the first weight value corresponding to the first estimated capacity, adjust the second weight value corresponding to at least one of the plurality of second estimated capacities so that the sum of the second weight values ​​corresponding to the plurality of second estimated capacities and the first weight value corresponding to the first estimated capacity is 1; wherein the second estimated capacity is the estimated capacity of the battery determined before the first estimated capacity.

[0069] In the above step 104, because the several second estimated capacities are multiple estimated capacities determined before the first estimated capacity, each second estimated capacity has a corresponding weight value, that is, the above second weight value, by adjusting the second weight value corresponding to at least the second estimated capacity among the above several second estimated capacities, the sum of the second weight values ​​corresponding to the several second estimated capacities and the first weight value corresponding to the first estimated capacity is 1, which facilitates the addition of the first estimated capacity in the subsequent steps to estimate the actual capacity of the battery.

[0070] Step 105: Estimate the actual capacity of the battery according to the plurality of second estimated capacities and the adjusted second weight values, and the first estimated capacity and the first weight value.

[0071] In the above step 105, a weighted average is calculated for the above-mentioned plurality of second estimated capacities according to the corresponding adjusted second weight values, and the second estimated capacity according to the above-mentioned first weight value, and the obtained result can be used as the actual capacity estimation value of the battery.

[0072] The method provided in the embodiment of the present application needs to calculate the process capacity between two capacity state identification points to obtain a first estimated capacity and a corresponding first weight value, and then adjust the second weight values ​​corresponding to several second estimated capacities determined previously, so as to dynamically adjust the weight value for the estimated capacity determined in each process, and then participate in obtaining the weighted average value to obtain the actual capacity of the battery. Without adding additional communication means, it is possible to realize capacity calculation for a battery cluster that does not meet the conventional full charge and discharge calibration capacity, while reducing the difference between the SOC calculated capacity and the actual capacity.

[0073] The method provided in the embodiment of the present application only needs to rely on the battery cluster management unit to perform calculations, and then the battery system management unit only needs to set each battery cluster to be fully charged when clusters are used in parallel to achieve capacity estimation.

[0074] In an embodiment of the present application, the capacity state identification point can be a relatively accurate state of charge value, then the process capacity is the process electrical quantity, that is, the capacity of the battery is represented by the electrical quantity; or the capacity state identification point can be a relatively accurate energy state value, then the process capacity is the process electrical energy, that is, the capacity of the battery is represented by the electrical energy.

[0075] When the capacity state identification point is the state of charge value and the process capacity is the process power, the battery capacity is estimated in the same way as when the capacity state identification point is the energy state value and the process capacity is the process power. The following is a specific description of the case where the capacity state identification point is the state of charge point and the process capacity is the process power.

[0076] In order to improve the accuracy of the estimation results, the two capacity state identification points involved in recording the process capacity should be the high charge state identification point and the low charge state identification point respectively.

[0077] Optionally, in one implementation, the above step 102 specifically includes:

[0078] The first process electric quantity between the full charge state point and the empty charge state point is recorded respectively, the second process electric quantity between the full charge state point and the deep discharge point, between the empty charge state point and the charge correction point, and between the charge correction point and the deep discharge point is recorded, and the third process electric quantity between the full charge state point and the rest charge state point, and between the charge correction point and the rest charge state point when the full charge state point is not passed.

[0079] In this embodiment, during the discharge process, after the full charge state point is identified, if the empty charge state point is also identified, the process power between the full charge state point and the empty charge state point is recorded as the above-mentioned first process power; during the charging process, after the empty charge state point is identified, if the full charge state point is also identified, the process power between the empty charge state point and the full charge state point is recorded as the above-mentioned first process power.

[0080] In this embodiment, during the discharge process, after the full charge state of charge point is identified, if a deep discharge point is also identified, the process electric quantity between the full charge state of charge point and the deep discharge point is recorded as the above-mentioned second process electric quantity; during the discharge process, after the charge correction point is identified, if a deep discharge point is also identified, the process electric quantity between the charge correction point and the deep discharge point is recorded as the above-mentioned second process electric quantity; during the discharge process, after the charge correction point is identified, if a discharge state of charge point is also identified, the process electric quantity between the charge correction point and the discharge state of charge point is recorded as the above-mentioned second process electric quantity.

[0081] In this embodiment, during the charging process, after the deep discharge point is identified, if the full charge state of charge point is also identified, the process electric quantity between the deep discharge point and the full charge state of charge point is recorded as the above-mentioned second process electric quantity; during the charging process, after the deep discharge point is identified, if the charge correction point is also identified, the process electric quantity between the deep discharge point and the charge correction point is recorded as the above-mentioned second process electric quantity; during the charging process, after the empty charge state of charge point is identified, if the charge correction point is also identified, the process electric quantity between the empty charge state of charge point and the charge correction point is recorded as the above-mentioned second process electric quantity.

[0082] In this embodiment, during the charging process, after the rest state of charge point is identified, if the full charge state of charge point is also identified, the process electric quantity between the rest state of charge point and the full charge state of charge point is recorded as the above-mentioned third process electric quantity; during the discharging process, after the full charge state of charge point is identified, if the rest state of charge point is also identified, the process electric quantity between the full charge state of charge point and the rest state of charge point is recorded as the above-mentioned third process electric quantity.

[0083] Optionally, in one implementation, the above step 103 includes steps 131 to 135:

[0084] Step 131: when a first process power between the full charge state point and the empty charge state point is recorded, determine a first calculated capacity of the battery according to a state of charge difference between the full charge state point and the empty charge state point and the first process power.

[0085] In step 131, when the first process power between the full charge state point and the empty charge state point is recorded, the first calculated capacity is determined as the first estimated capacity by dividing the first process power by the charge state difference between the full charge state point and the empty charge state point.

[0086] Step 132: When a second process electric quantity between the full charge state point and the deep discharge point is recorded, a second calculated capacity of the battery is determined according to a state of charge difference between the full charge state point and the deep discharge point and the second process electric quantity.

[0087] In step 132, when the second process power between the full charge state point and the deep discharge point is recorded, the second process power is divided by the charge state difference between the full charge state point and the deep discharge point to determine the second calculated capacity as the first estimated capacity.

[0088] Step 133: When the state of charge difference between the empty state of charge point and the charge correction point and the second process power are recorded, determine the second calculated capacity of the battery according to the state of charge difference between the empty state of charge point and the charge correction point and the second process power.

[0089] In step 133, when the second process electric quantity between the empty state of charge point and the charge correction point is recorded, the second process electric quantity is divided by the state of charge difference between the empty state of charge point and the charge correction point to determine the second calculated capacity as the first estimated capacity.

[0090] Step 134: when a second process electric quantity between the charge correction point and the deep discharge point is recorded, a second calculated capacity of the battery is determined according to a charge state difference between the charge correction point and the deep discharge point and the second process electric quantity.

[0091] In step 134, when the second process electric quantity between the charge correction point and the deep discharge point is recorded, that is, when the second process electric quantity between the empty state of charge point and the deep discharge point is recorded during the discharge process or the charging process, the second process electric quantity is divided by the state of charge difference between the charge correction point and the deep discharge point to determine the second calculated capacity as the first estimated capacity.

[0092] Step 135: When a third process power between the full charge state point and the rest state point is recorded, determine a third calculated capacity of the battery according to a state of charge difference between the full charge state point and the rest state point and the third process power.

[0093] In step 135, when the first process power between the full charge state point and the rest charge state point is recorded, the first calculated capacity is determined as the first estimated capacity by dividing the first process power by the charge state difference between the full charge state point and the rest charge state point.

[0094] In the above implementation, for different process electric quantities, the state of charge difference between two corresponding charge identification points is divided to determine the corresponding estimated battery capacity.

[0095] Optionally, in one implementation, determining a first weight value corresponding to a current first estimated capacity of the battery includes:

[0096] When the first estimated capacity is the first calculated capacity, a first weight value corresponding to the first estimated capacity is (N+4) / (N+M+Q);

[0097] In a case where the first estimated capacity is the second calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q);

[0098] In a case where the first estimated capacity is the third calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q);

[0099] Among them, N, M, and Q are all positive integers.

[0100] In the above implementation, considering that the estimated capacity determined from the full charge state point to the empty charge state point, and from the empty charge state point to the full charge state point is more accurate, a higher weight value is set; and the estimated capacity determined from the full charge state point to the deep discharge point, the deep discharge point to the full charge state point, the empty charge state point to the charging correction point, the charging correction point to the empty charge state point, the charging correction point to the deep discharge point, the deep discharge point to the charging correction point, the full charge state point to the static charge state point, and the static charge state point to the full charge state point is slightly less accurate and similar, so it is set to have a lower and the same weight value, so as to match the accuracy of the estimated capacity determined by the power of each process compared to the actual capacity of the battery, dynamically adjust the weight value, and then participate in obtaining the weighted average value, so as to more accurately estimate the actual capacity of the battery.

[0101] Optionally, in a specific implementation, by setting the values ​​of N, M, and Q to be the same, the accuracy of the first computing capacity, the second computing capacity, and the third computing capacity can be accurately matched.

[0102] Optionally, in a specific implementation, N, M, and Q are all set to 5, which is suitable for matching the capacity estimation of the lithium iron phosphate battery.

[0103] Optionally, in one implementation, the above step 104 includes steps 141 to 144:

[0104] Step 141. When the first estimated capacity is the first calculated capacity, the first estimated capacity is used to replace all the second estimated capacities in the first array, and the first estimated capacity is filled into the second array twice, and the first estimated capacity is filled into the third array twice; the array lengths of the first array, the second array and the third array are N, M and Q respectively.

[0105] In this step 141, considering that the first calculated capacity is the core capacity result after full charge and discharge, its accuracy is relatively high. When the first estimated capacity is the first calculated capacity, the first estimated capacity is used to replace all the second estimated capacities in the first array, and replace the 2 second estimated capacities first added to the second array, and replace the 2 second estimated capacities first added to the third array, thereby realizing the update of the original 9 second estimated capacities in the first array, the second array and the third array.

[0106] Step 142: When the first estimated capacity is the second calculated capacity, fill the second array with the first estimated capacity once.

[0107] In step 142, considering that the second calculated capacity is the core capacity result involving the deep discharge point and / or the charge correction point, and its accuracy is relatively low, when the first estimated capacity is the second calculated capacity, only the first estimated capacity is used to replace a second estimated capacity first added to the second array, thereby realizing the update of the original second estimated capacity in the second array.

[0108] Step 143: When the first estimated capacity is the third calculated capacity, fill the first estimated capacity into the third array once.

[0109] In step 143, considering that the third calculated capacity is the core capacity result involving the static state of charge point, its accuracy is relatively low. When the first estimated capacity is the third calculated capacity, only the first estimated capacity is used to replace a second estimated capacity first added to the third array, thereby realizing the update of the original second estimated capacity in the second array.

[0110] Step 144: Determine a second weight value corresponding to each second estimated capacity according to the number of second estimated capacities in the first array, the second array, and the third array.

[0111] In step 144, for each second estimated capacity, the total amount in the first array, the second array and the third array is counted and divided by the sum of the array lengths of the first array, the second array and the third array to determine the second weight value corresponding to the second estimated capacity.

[0112] In the above implementation, one or two of the first array, the second array and the third array are filled respectively according to the different first estimated capacities, so as to achieve the effect of adjusting the second weight value of the original second estimated capacity in each array.

[0113] In actual use, the array length of the above-mentioned first array, second array and third array is 5, and all data are read in during initialization, and the 5 elements in the first array are filled with data in the non-volatile memory. The data initialized and applied in the second array is the second calculation capacity, and the data initialized and applied in the third array is the third calculation capacity.

[0114] Optionally, in a specific implementation, the actual capacity of the battery is estimated using the arithmetic mean of the elements in the first array, the second array, and the third array.

[0115] Among them, when the secondary battery is charged and discharged for the first time, because the second estimated capacity as the historical estimated capacity has not yet been generated through capacity estimation, the historical data of the second calculated capacity and the historical data of the third calculated capacity are not recorded in the memory, so that the valid elements filled in the second array and the third array are likely to be less than 5; when the valid elements in the second array and the third array do not meet 5, only the mean of the elements in the first array is output as the actual capacity of the battery; when the second array or the third array meets the requirement of 5 valid elements, the arithmetic mean of all elements in the first array and the second array is calculated and output as the actual capacity of the battery; when all three arrays meet the requirement of 5 valid elements, the output result is the arithmetic mean of all elements as the actual capacity of the battery.

[0116] Optionally, in one implementation manner, the capacity estimation method provided in the embodiment of the present application further includes:

[0117] After the first capacity state identification point is identified, if the second capacity state identification point is not identified after a preset period of time, the process capacity recorded with the first charge state point as the starting point is discarded, wherein the first capacity state identification point and the second capacity state identification point are two different capacity state identification points.

[0118] In this implementation, because after the first capacity state identification point is identified, the battery capacity estimation is triggered, that is, the above steps 102 to 105 are executed. If the second capacity state identification point is not identified when the timing reaches the preset time after the core capacity calculation is turned on, the process capacity recorded with the first charge state point as the starting point is discarded, that is, the capacity estimation process involving the first charge identification point is closed, which can effectively avoid further expansion of the estimated SOC error due to the system's own power consumption.

[0119] See also Figure 3 , showing a logical principle diagram of the capacity estimation method provided in an embodiment of the present application.

[0120] like Figure 3 As shown, when the energy storage system is operating normally, the current in the BCMU acquisition loop is integrated in ampere-hours to calculate the current SOC and charge and discharge capacity of the battery cluster; when the relatively accurate nuclear power status identification point judgment conditions are met, the SOC value and charge and discharge capacity at this time are recorded, and the nuclear capacity calculation is started.

[0121] During operation, if the BCMU determines that another relatively accurate nuclear power status condition is met, and this condition is the end condition for the nuclear capacity calculation that has been turned on, the SOC value at this time is used to calculate the difference, and the charge and discharge power at this time is used to calculate the charge and discharge amount difference. The charge and discharge amount in the entire SOC interval is estimated through the charge and discharge power in the SOC interval, and the nuclear capacity is completed.

[0122] Among them, when the full charge state identification point and the empty state identification point are identified in sequence during the discharge process, the capacity core condition of situation ① is determined; when the empty state identification point and the full charge state identification point are identified in sequence during the charging process, the capacity core condition of situation ② is determined; when the capacity core condition of situation ① / ② is met, the weight value of the corresponding estimated capacity is determined by using the proportion of the situation that meets the conditions in the aforementioned first array, second array and third array;

[0123] Among them, when the capacity-reducing conditions of situations ① and ② are not met, during the discharge process, the full charge state identification point and the deep discharge point are identified in sequence, or the charge correction point and the deep discharge point are identified in sequence, or the charge correction point and the empty state identification point are identified in sequence, then it is determined that the capacity-reducing conditions of situation ③ are met;

[0124] When the capacity-reducing conditions of situations ① and ② are not met, the capacity-reducing conditions of situation ④ are determined to be met if the deep discharge point and the full charge state recognition point are identified in sequence during the discharge process, or the deep discharge point and the charge correction point are identified in sequence, or the empty state recognition point and the charge correction point are identified in sequence;

[0125] When the capacity conditions of situation ③ / ④ are met, the weight value of the corresponding estimated capacity is determined by using the proportion of the situation that meets the conditions in the first array, the second array and the third array;

[0126] Among them, when the nuclear capacity conditions of situations ①, ②, ③, and ④ are not met, the nuclear capacity conditions of situation ⑤ are determined to be met when the full charge state recognition point and the static charge state recognition point are identified in sequence during the discharge process;

[0127] When the capacity-reducing conditions of situations ①, ②, ③, and ④ are not met, the static state of charge point and the full charge state of charge identification point are identified in sequence during the charging process, and it is determined that the capacity-reducing condition of situation ⑥ is met;

[0128] When the capacity conditions of situation ⑤ / ⑥ are met, the weight value of the corresponding estimated capacity is determined by using the proportion of the situation that meets the conditions in the aforementioned first array, second array and third array.

[0129] The present application also provides an electronic device, such as Figure 4 As shown, it includes a processor 401 , a communication interface 402 , a memory 403 and a communication bus 404 , wherein the processor 401 , the communication interface 402 , and the memory 403 communicate with each other via the communication bus 404 .

[0130] The memory 403 is used to store computer programs.

[0131] When the processor 401 is used to execute the program stored in the memory 403, the following steps are implemented:

[0132] Identify at least two capacity status identification points during the battery charging and discharging process;

[0133] Recording the process capacity between any two of the capacity state identification points;

[0134] For each of the process capacities, determining a current first estimated capacity of the battery and a first weight value corresponding to the first estimated capacity according to the two capacity state identification points corresponding to the process capacity;

[0135] According to the first weight value corresponding to the first estimated capacity, adjusting the second weight value corresponding to at least one of the plurality of second estimated capacities so that the sum of the second weight values ​​corresponding to the plurality of second estimated capacities and the first weight value corresponding to the first estimated capacity is 1; wherein the second estimated capacity is the estimated capacity of the battery determined before the first estimated capacity;

[0136] The actual capacity of the battery is estimated according to the plurality of second estimated capacities and the adjusted second weight values, and the first estimated capacity and the first weight value.

[0137] The processor 401 may also implement other steps in the above-mentioned secondary battery capacity estimation method, which will not be described in detail here.

[0138] The communication bus mentioned in the above electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus or a Controller Area Network (CAN) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0139] The communication interface is used for communication between the above electronic device and other devices.

[0140] The memory may include a random access memory (RAM) or a non-volatile memory, such as at least one disk memory. Alternatively, the memory may also be at least one storage device located away from the aforementioned processor.

[0141] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0142] In another embodiment provided in the present application, a computer-readable storage medium is provided, in which instructions are stored. When the computer-readable storage medium is run on a computer, the computer executes the secondary battery capacity estimation method described in the above embodiment.

[0143] In another embodiment provided in the present application, a computer program product including instructions is also provided. When the computer program product is run on a computer, the computer is enabled to execute the capacity estimation method of the secondary battery described in the above embodiment.

[0144] In another embodiment provided in the present application, a battery management system is also provided. The battery management system includes the above-mentioned electronic device.

[0145] In another embodiment provided in the present application, an energy storage system is provided, including a secondary battery, wherein the secondary battery serves as an energy storage unit of the energy storage system, and the energy storage system also includes the above-mentioned electronic device.

[0146] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0147] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0148] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the embodiments of the device, electronic device, computer-readable storage medium and computer program products containing instructions, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0149] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A method for estimating the capacity of a secondary battery, characterized in that: include: Identify at least two capacity status identification points during the battery charging and discharging process; Recording the process capacity between any two of the capacity state identification points; For each of the process capacities, determining a current first estimated capacity of the battery and a first weight value corresponding to the first estimated capacity according to the two capacity state identification points corresponding to the process capacity; According to the first weight value corresponding to the first estimated capacity, adjusting the second weight value corresponding to at least one of the plurality of second estimated capacities so that the sum of the second weight values ​​corresponding to the plurality of second estimated capacities and the first weight value corresponding to the first estimated capacity is 1; wherein the second estimated capacity is the estimated capacity of the battery determined before the first estimated capacity; The actual capacity of the battery is estimated according to the plurality of second estimated capacities and the adjusted second weight values, and the first estimated capacity and the first weight value.

2. The capacity estimation method according to claim 1, characterized in that: The capacity state identification point includes a charge state identification point, and the process capacity includes a process power; or The capacity state identification point includes an energy state identification point, and the process capacity includes process energy.

3. The capacity estimation method according to claim 2, characterized in that: The at least two capacity state identification points include a full charge state point, an empty charge state point, a deep discharge state point, a charge correction point, and a static charge state point; the process capacity includes the process power; Recording the process capacity between two adjacent capacity state identification points includes: The first process electric quantity between the full charge state point and the empty charge state point is recorded respectively, the second process electric quantity between the full charge state point and the deep discharge point, between the empty charge state point and the charge correction point, between the charge correction point and the deep discharge point is recorded, and the third process electric quantity between the full charge state point and the static charge state point is recorded.

4. The capacity estimation method according to claim 3, characterized in that: Determining a first current estimated capacity of the battery according to the two capacity state identification points corresponding to the process capacity includes: When a first process electric quantity between the full charge state of charge point and the empty charge state of charge point is recorded, a first calculated capacity of the battery is determined according to a state of charge difference between the full charge state of charge point and the empty charge state of charge point and the first process electric quantity; When a second process electric quantity between the full charge state point and the deep discharge point is recorded, determining a second calculated capacity of the battery according to a state of charge difference between the full charge state point and the deep discharge point and the second process electric quantity; When the state of charge difference between the empty state of charge point and the charge correction point and the second process power are recorded, determining the second calculated capacity of the battery according to the state of charge difference between the empty state of charge point and the charge correction point and the second process power; When a second process electric quantity between the charge correction point and the deep discharge point is recorded, a second calculated capacity of the battery is determined according to a charge state difference between the charge correction point and the deep discharge point and the second process electric quantity; When a third process power between the full charge state point and the rest state point is recorded, a third calculated capacity of the battery is determined according to a state of charge difference between the full charge state point and the rest state point and the third process power.

5. The capacity estimation method according to claim 4, characterized in that: Determining a first weight value corresponding to a current first estimated capacity of the battery includes: When the first estimated capacity is the first calculated capacity, a first weight value corresponding to the first estimated capacity is (N+4) / (N+M+Q); In a case where the first estimated capacity is the second calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q); In a case where the first estimated capacity is the third calculated capacity, a first weight value corresponding to the first estimated capacity is 1 / (N+M+Q); Among them, N, M, and Q are all positive integers.

6. The capacity estimation method according to claim 5, characterized in that: According to the first weight value corresponding to the first estimated capacity, adjusting the second weight value corresponding to at least one of the plurality of second estimated capacities includes: In a case where the first estimated capacity is the first calculated capacity, all second estimated capacities in the first array are replaced by the first estimated capacity, and the first estimated capacity is filled twice into the second array, and the first estimated capacity is filled twice into the third array; the array lengths of the first array, the second array, and the third array are N, M, and Q, respectively; When the first estimated capacity is the second calculated capacity, filling the second array with the first estimated capacity once; When the first estimated capacity is the third calculated capacity, filling the third array with the first estimated capacity once; According to the quantity of each second estimated capacity in the first array, the second array and the third array, a second weight value corresponding to each second estimated capacity is determined respectively.

7. The capacity estimation method according to claim 5, characterized in that: The values ​​of N, M, and Q are the same.

8. The capacity estimation method according to claim 5, characterized in that: N, M, and Q are all 5.

9. The capacity estimation method according to claim 1, characterized in that: The method further comprises: After the first capacity state identification point is identified, if the second capacity state identification point is not identified after a preset period of time, the process capacity recorded with the first charge state point as the starting point is discarded, wherein the first capacity state identification point and the second capacity state identification point are two different capacity state identification points.

10. The capacity estimation method according to claim 2, characterized in that: In the case where the capacity identification points include charge state identification points, recording the process capacity between any two of the capacity state identification points includes: The current between any two charge state identification points is integrated in ampere-hours to calculate the process power.

11. An electronic device, characterized in that: include: A processor, a communication interface, a memory and a communication bus; wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory, used to store computer programs; A processor, configured to implement the steps of the capacity estimation method according to any one of claims 1 to 9 when executing a program stored in the memory.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the capacity estimation method according to any one of claims 1 to 10 are implemented.

13. A battery management system, characterized in that: Comprising the electronic device as claimed in claim 11.

14. An energy storage system, comprising a secondary battery, wherein the secondary battery is used as an energy storage unit of the energy storage system, characterized in that: The energy storage system further includes the electronic device as claimed in claim 11 or the battery management system as claimed in claim 13.

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