A distributed computing and storage SOC method

Abstract

The present invention discloses a distributed calculation and storage method for SOC, comprising the following steps: Step 1) storing battery cell parameters in a battery management unit (BMU), and uploading the BMU's algorithm parameters to a battery control unit (BCU) after power-on; Step 2) synchronizing the BCU's serial number to each module each time the BCU is powered on, and sending the serial number of the bound BCU to the BCU each time the BCU is powered on; Step 3) storing only one battery cell parameter table in the BCU, avoiding the need to continuously add battery cell algorithm parameters and reducing the requirement for MCU flash memory; Step 4) synchronizing the total battery voltage and average current to the BMU in real time, and the BMU synchronously estimating the SOC. The present invention can improve SOC accuracy and reduce the risk of SOC estimation accuracy when replacing battery cells; it can also solve the SOC accuracy problem of inconsistent module capacities for the same battery cell model, reducing the requirement for after-sales module replacement.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery modules, and in particular relates to a distributed calculation and storage SOC method for a battery module. Background Art

[0002] In existing multi-module battery series applications, a battery control unit (BCU) and battery management unit (BMU) are typically used. The BCU is responsible for battery capacity estimation, total voltage and current collection, battery data aggregation and analysis, power-on and power-off strategy management, and external communication. The battery calibration parameters used for battery capacity estimation are stored in the BCU. The BCU estimates the SOC by collecting current, temperature, voltage, and other data, combined with the battery calibration parameters. The BMU in the module is only responsible for collecting battery-related parameters (such as voltage and temperature) and communicating with the BCU.

[0003] However, the shortcomings of BCU are as follows:

[0004] 1) The BCU can only record known battery charge calibration parameters. When multiple modules with different battery cells are used simultaneously, the BCU cannot accurately combine the battery parameters to estimate the SOC with high precision. This places high demands on module matching, which is severely limited in practical applications.

[0005] 2) When the system needs to replace individual modules, due to the consistency differences between the existing module and the replacement module, for example, the existing module has been used for a period of time, while the new replacement module has not been used. The BCU cannot identify the module and can only use the known parameters. In this case, it is also impossible to estimate the SOC with high accuracy.

[0006] 3) When multiple battery cells are used simultaneously in a project, for example, to reduce costs, battery cells may be replaced or their parameters may be changed. In this case, the BCU needs to support multiple battery cell calibration parameter tables, which increases the FLASH size of the MCU in the BCU and requires higher material and R&D costs for the MCU.

[0007] 4) When the BCU's SOC estimation fails in a project, the operation and status of the entire system are affected. For example, the current remaining usage time or range cannot be estimated, and power cannot be limited reasonably.

[0008] The existing solution cannot accurately estimate SOC accuracy by combining several application scenarios. Summary of the Invention

[0009] To solve the above problems, the primary purpose of the present invention is to provide a distributed calculation and storage SOC method, which can improve SOC accuracy and reduce the risk of SOC estimation accuracy when replacing battery cells; and can solve the SOC accuracy problem of inconsistent module capacities for the same battery cell model, thereby reducing the requirements for after-sales module replacement.

[0010] Another object of the present invention is to provide a distributed computing and storage SOC method, which can use parameters stored in other modules for synchronization, utilize the system redundant storage solution to reduce the system's storage failure risk; and can perform diagnosis through the SOC values of other nodes to avoid single point failure.

[0011] To achieve the above objectives, the technical solutions of the present invention are as follows.

[0012] A distributed computing and storage SOC method, the method comprising the following steps:

[0013] Step 1) The cell parameters are stored in the BMU, and after power-on, the BMU algorithm parameters are uploaded to the BCU.

[0014] If the battery cells are of the same type, the BCU directly stores a set of battery cell parameters as the SOC algorithm parameters. If there are multiple battery cells in the system, the battery cell with the worst performance is used as the SOC algorithm parameter, which can solve the problem of mixing modules with different battery cells.

[0015] Step 2) Each time the BCU is powered on, the BCU synchronizes the serial number of the local unit to each module, and each time the BMU is powered on, it sends the serial number of the bound BCU to the BCU;

[0016] If the BCU detects a discrepancy between the serial number and its own, it will re-update the SOC value and synchronize the BCU serial number with the BMU. This can solve the problem of SOC estimation accuracy when the module is replaced.

[0017] Step 3) Only one cell parameter table is stored in the BCU, which avoids the continuous addition of cell algorithm parameters and reduces the requirement for MCU's FLASH space.

[0018] Step 4): The BCU synchronizes the total battery voltage and average current to the BMU in real time, and the BMU estimates the SOC synchronously.

[0019] Because the BMU's algorithm parameters are directly bound to the module, it can estimate the SOC with high precision. The BMU's estimated SOC is sent to the BCU, which then performs diagnosis based on its own estimated SOC and the SOC estimated by each BMU. This prevents an abnormal SOC from causing an abnormal SOC in the system estimate. Redundant design improves system reliability.

[0020] Among them, the battery cell parameter table contains project information, such as project number, which can realize the problem of algorithm parameters and project error prevention, and avoid the wrong module being connected to the system, which leads to system abuse.

[0021] Further comprising the steps of:

[0022] 101. Write the SOC calibration into the BMU. The SOC calibration parameters must include the SOC algorithm calibration parameters and the foolproof parameters. When the system is powered on, the BCU first reads the BMU's foolproof parameters. If the foolproof parameters match, the BCU reads the BMU's SOC algorithm calibration parameters. By comparing the SOC algorithm calibration parameters of each BMU, the most suitable parameter table is found and saved in the BCU.

[0023] 102, BCU collects current and total voltage in real time, and obtains data such as cell voltage and temperature collected by BMU through CAN communication, and calculates SOC in real time;

[0024] The BCU regularly broadcasts data such as total voltage, current, and charge / discharge status to each BMU. After receiving the total voltage, current, and charge / discharge status, the BMU estimates the SOC within the BMU module in real time and sends the SOC to the BCU.

[0025] 103, when the BCU and BMU estimate the SOC in real time, they store the real-time running SOC parameters, such as the remaining capacity, SOC, number of cycles, and other parameters updated in real time related to the SOC estimation;

[0026] 104. The BCU compares the SOC calculated locally with the SOC of each module to diagnose whether the SOC has failed. If it has failed, the BCU continues to calculate the SOC with reference to the SOC value of the module that has not failed until the SOC estimation returns to normal.

[0027] The technical effects of the present invention are as follows:

[0028] 1) When multiple battery cells appear in the system, it can improve the SOC accuracy and reduce the risk of SOC estimation accuracy when replacing battery cells;

[0029] 2) It can solve the SOC accuracy problem of inconsistent module capacities for the same battery cell model, reducing the requirement for after-sales module replacement;

[0030] 3) Since the system stores SOC calibration parameters in a distributed manner, if one module fails, the parameters stored in other modules can be used for synchronization, utilizing the system’s redundant storage solution to reduce the risk of storage failure.

[0031] 4) Since the BCU and each BMU calculate SOC, when one node calculates SOC abnormally, diagnosis can be performed through the SOC values of other nodes to avoid single point failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the communication network implemented by the present invention.

[0033] Figure 2 It is the overall flow chart implemented by the present invention.

[0034] Figure 3 This is a flow chart of the SOC parameter synchronization implemented by the present invention.

[0035] Figure 4 This is a flow chart of SOC diagnosis and SOC correction implemented by the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] The distributed computing and storage SOC method implemented by the present invention includes the following steps:

[0038] 1) The module has its SOC calibration written into the BMU at the factory, and the module's software also supports SOC estimation. The SOC calibration parameters must include the SOC algorithm calibration parameters and foolproofing parameters. When the system is powered on, the BCU first reads the BMU's foolproofing parameters. If the foolproofing parameters match, it then reads the BMU's SOC calibration parameters. By comparing the algorithm parameters of each BMU, it finds the most appropriate parameter table and saves it in the BCU. The BCU also supports SOC estimation.

[0039] 2) During system operation, the BCU collects current and total voltage in real time, and acquires cell voltage and temperature data collected by the BMU via CAN communication, calculating the SOC in real time. The BCU also regularly broadcasts data such as total voltage, current, and charge / discharge status to each BMU. After receiving the total voltage, current, and charge / discharge status, the BMU estimates the SOC within its own module in real time and sends the SOC to the BCU.

[0040] 3) When the BCU and BMU estimate the SOC in real time, they store the real-time running SOC parameters, such as remaining capacity, SOC, number of cycles, and other parameters related to the SOC estimation that are updated in real time;

[0041] 4) The BCU compares the SOC calculated locally with the SOC of each module to diagnose whether the SOC has failed. If it has failed, the BCU continues to calculate the SOC with reference to the SOC value of the module until the SOC estimation returns to normal.

[0042] like Figure 1 As shown, BCU is the battery control power supply and BMU is the battery management unit;

[0043] The BCU is responsible for total voltage and current collection, charge and discharge status analysis, power on and off management, external device communication, and intranet BMU management.

[0044] The BMU is responsible for functions such as battery cell voltage, battery temperature, battery balancing, and BCU communication.

[0045] like Figure 2 As shown in the figure, after the system is powered on, the BCU first completes the SOC parameter synchronization process. After completing the parameter synchronization, the BCU reads the data of the BMU in real time. The data includes single cell voltage, battery temperature, SOC, SOH, number of cycles, remaining capacity, fully charged available capacity and other data. The BCU also broadcasts the BCU data to the BMU at the same time. The data includes total voltage, total current, charge and discharge status, SOC, SOH, number of cycles, remaining capacity, fully charged available capacity and other data.

[0046] Figure 3 As shown, the SOC parameter synchronization process is described as follows:

[0047] 1) After the system is powered on, the BCU reads the item number in the cell parameters of the BMU and uses the item number as the foolproof code of the SOC parameters. If the foolproof code does not match, a BMU mismatch fault is reported;

[0048] 2) If the anti-foolproof codes match, the BCU further reads the BCU serial number stored in each BMU and compares it with its own serial number. If they are inconsistent, the BCU sets ResetBcuSoc to TRUE, indicating that the BCU SOC needs to be recalculated. The BCU then sends its own serial number to the BMU, which stores it.

[0049] 3) The BCU then reads the cell parameter information from the BMU (this parameter is not the cell calibration parameter, but mainly the cell specification model, calibration parameter validity status, and performance level). The calibration parameter validity mainly refers to the verification result of the cell calibration parameter. If the verification is correct, it is valid; otherwise, it is invalid. The performance level can be known during the design stage.

[0050] 4) If the battery cell models of all BMUs are the same, the battery cell parameters of BMU1 are read as the SOC estimation parameters of the BCU;

[0051] 5) If there is any inconsistency, the validity of the calibration parameters is determined. If the calibration parameters are valid, the BCU selects the worst-performing parameters from all BMU cell models as the BCU SOC estimation parameters to reduce the SOC estimation error.

[0052] 6) If the calibration parameters are invalid, the BCU searches for the same type of battery cell from all BMUs. If it is found, the parameters are synchronized to the BMU. If it is not found, the BCU will not refer to the SOC value of the BMU.

[0053] 7) The BCU reads the real-time stored parameters of each BMU, such as SOH and SOC. If the SOH of a BMU is ≠ the SOH of the BMU stored in the BCU, or the error between the SOC of the BMU and the SOC of the BCU is greater than 10%, ResetBcuSoc is set to TRUE, indicating that the SOC of the BCU needs to be recalculated.

[0054] 8) If the BCU determines that ResetBcuSoc is TRUE, the BCU collects the SOCs of all valid BMUs and obtains a new SOC by weighting. The weighting formula is as follows:

[0055] SOC_new=K1*SOC1+K2*SOC2+Kn*SOCn,

[0056] Wherein, n represents the number of modules, K1+K2...+Kn=1.

[0057] SOC diagnosis and correction SOC process such as Figure 4 As shown:

[0058] 1) BCU diagnoses whether the change value of all nodes (including all BMUs and BCUs) exceeds △

[0059] SOC_Delta (e.g. 15%), the calculation start time of all nodes is the same moment. In theory, the change rate of all nodes is very close. If the error is large, it means that there may be an abnormality in the SOC calculation;

[0060] 2) BCU diagnoses the SOC change value of all nodes during this period △SOCn_Interval:

[0061] △SOCn_Interval=|SOCn_New-SOCn_Previous|, n=N+1, N is the number of modules;

[0062] 3) BCU sums the △SOCn_Interval of all valid nodes and takes the average △SOCn_Average:

[0063] △SOC_Average=(△SOC0_Interval+△SOC1_Interval+△

[0064] SOCn_Interval) / n;

[0065] A valid node is a node that has no SOC abnormality diagnosed;

[0066] 4) BCU calculates △SOC_Average and the error △SOCn_Err of all nodes:

[0067] △SOCn_Err=|△SOC_Average-△SOCn_Interval|

[0068] 5) If △SOCn_Err>△SOC_Delta / 2, the SOC estimation of this node is considered abnormal, and the invalid SOC node of this node is set to 1, and the correction and recovery are carried out after full charging or emptying;

[0069] △SOC_Delta / 2 is an example value and can be adjusted according to actual conditions;

[0070] 6) When an invalid node is in a fully charged state, the SOC of the node is corrected to 100%, and the invalid state of all nodes is canceled, allowing the module to participate in the system SOC calculation again;

[0071] 7) When an invalid node is in the empty state, the SOC of the node is corrected to 0%, and the invalid state of all nodes is canceled, allowing the module to participate in the system SOC calculation again.

[0072] In summary, the advantages of the present invention are as follows:

[0073] 1. The present invention stores the cell parameters in each module and synchronizes the module cell parameters to the BCU, which can reduce the impact on SOC accuracy when modules are freely matched;

[0074] 2. When the present invention diagnoses that the cell calibration parameters of a certain node are lost, the parameters can be obtained from other nodes and resynchronized to the node, avoiding parameter loss caused by storage anomalies and improving the fault tolerance of the system through distributed storage and recovery;

[0075] 3. The present invention adopts distributed SOC calculation. The SOC calculated by the BMU and the SOC calculated by the BCU diagnose each other. The redundant design improves the reliability of the system. It can also not affect the operation of the system in the event of a single point failure and can quickly repair the SOC estimation problem.

[0076] 4. The present invention also prevents mistakes in the cell parameters to avoid incorrect module pairing.

[0077] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A distributed computing and storage SOC method, characterized in that The method comprises the following steps: Step 1) The cell parameters are stored in the BMU, and after power-on, the BMU algorithm parameters are uploaded to the BCU; Step 2) Each time the BCU is powered on, the BCU synchronizes the serial number of the local unit to each module, and each time the BMU is powered on, it sends the serial number of the bound BCU to the BCU; Step 3) Only one cell parameter table is stored in the BCU, which avoids the continuous addition of cell algorithm parameters and reduces the requirement for MCU's FLASH space. Step 4) The BCU synchronizes the total battery voltage and average current to the BMU in real time, and the BMU estimates the SOC synchronously; After the system is powered on, the BCU first completes the SOC parameter synchronization process. The SOC parameter synchronization process is as follows: 201) After the system is powered on, the BCU reads the item number in the cell parameters of the BMU and uses the item number as the anti-foolproof code of the SOC parameters; 202) If the anti-foolproof codes match, the BCU further reads the BCU serial number stored in each BMU, compares the read serial number with its own serial number, and sets ResetBcuSoc to TRUE if they are inconsistent. The BCU then sends its own serial number to the BMU, which stores it. 203) BCU then reads the cell parameter information in BMU; wherein the calibration parameter validity is the verification result of the cell calibration parameter, if the verification is correct, it is valid, otherwise it is invalid; 204) If the battery cell models of all BMUs are the same, read the battery cell parameters of BMU1 as the SOC estimation parameters of BCU; 205) If they are inconsistent, the validity of the calibration parameters is determined. If the calibration parameters are valid, the BCU selects the worst performance parameters from all BMU cell models as the BCU SOC estimation parameters; 206) If the calibration parameters are invalid, the BCU searches for the same type of battery cell from all BMUs. If it is found, the parameters are synchronized to the BMU. If it is not found, the BCU will not refer to the SOC value of the BMU. 207) The BCU reads the real-time stored parameters of each BMU again. If the SOH of the BMU is ≠ the SOH of the BMU stored in the BCU or the error between the SOC of the BMU and the SOC of the BMU stored in the BCU exceeds 10%, ResetBcuSoc is set to TRUE. 208) If the BCU determines that ResetBcuSoc is TRUE, the BCU collects the SOCs of all valid BMUs and obtains a new SOC by weighting. The weighting formula is as follows: SOC_new=K1*SOC1+K2*SOC2+Kn*SOCn, Wherein, n represents the number of modules, K1+K2...+Kn=1.

2. A distributed computing and storage SOC method as claimed in claim 1, characterized in that In step 1) of the method, if the same type of battery cells are stored, the BCU directly stores a set of battery cell parameters as SOC algorithm parameters. When there are multiple types of battery cells in the system, the battery cell with the worst performance is taken as the SOC algorithm parameter.

3. A distributed computing and storage SOC method as claimed in claim 2, characterized in that In step 2), if the BCU diagnoses that the serial number is inconsistent with its own, the BCU re-updates the SOC value and synchronizes the BCU serial number to the BMU.

4. A distributed computing and storage SOC method as claimed in claim 3, characterized in that Further comprising the steps of:

101. Write the SOC calibration into the BMU. The SOC calibration parameters must include the SOC algorithm calibration parameters and the foolproof parameters. When the system is powered on, the BCU first reads the BMU's foolproof parameters. If the foolproof parameters match, the BCU reads the BMU's SOC algorithm calibration parameters. By comparing the SOC algorithm calibration parameters of each BMU, the most suitable parameter table is found and saved in the BCU. 102, BCU collects current and total voltage in real time, and obtains cell voltage and temperature data collected by BMU through CAN communication, and calculates SOC in real time; 103, when the BCU and BMU estimate the SOC in real time, they store the real-time running SOC parameters, such as the remaining capacity, SOC, number of cycles, and real-time updated parameters related to the SOC estimation; 104. The BCU compares the SOC calculated locally with the SOC of each module to diagnose whether the SOC has failed. If it has failed, the BCU continues to calculate the SOC with reference to the SOC value of the module that has not failed until the SOC estimation returns to normal.

5. A distributed computing and storage SOC method as claimed in claim 4, characterized in that In step 102, the BCU regularly broadcasts the total voltage, current, and charge and discharge status data to each BMU. After receiving the total voltage, current, and charge and discharge status, the BMU estimates the SOC within the BMU module in real time and sends the SOC to the BCU.

Images