Method for estimating soh value of battery pack, battery management system and storage medium

Abstract

The application relates to a SOH value estimation method of a battery pack, a battery management system and a storage medium. The SOH value estimation method comprises the following steps: obtaining the cumulative discharge capacity of the battery pack since work; obtaining the first SOH value of the battery pack according to the cumulative discharge capacity; obtaining the actual battery capacity of the battery pack in the case that the battery pack is from a full state to a static state; obtaining the second SOH value of the battery pack according to the actual battery capacity; comparing the first SOH value and the second SOH value; if the first SOH value is greater than the second SOH value, taking the second SOH value as the estimated SOH value; and updating the current SOH value of the battery pack according to the estimated SOH value. The application can more accurately estimate the SOH value, and then can realize more efficient management of the battery pack.

Description

TECHNICAL FIELD

[0001] The present application generally relates to the field of battery management. More particularly, the present application relates to a method for estimating SOH value of a battery pack, a battery management system and a storage medium. BACKGROUND

[0002] The battery pack involves the cooperation and management of multiple batteries. In order to improve the efficiency of the battery pack, the parameters of the battery pack need to be monitored and managed, such as the SOH value (State of Health) of the battery pack, which represents the size of the output capacity of the battery pack. The health status of the battery pack will decay with use until it cannot meet the use requirements. Therefore, monitoring the SOH value can keep track of the state of the battery pack at all times, facilitating the use and maintenance of the user.

[0003] There are currently SOH estimation methods based on open-circuit voltage, which calculate the change of battery capacity in the same OCV interval to estimate the current capacity and SOH of the battery. There are also SOH estimation methods based on battery internal resistance, which are aimed at the specific capacity loss process of the battery in the use stage, and combine the battery working temperature with the internal resistance mechanism model, combined with the internal resistance online identification technology, to realize the SOH estimation in a wide temperature range. However, the current SOH value estimation method usually has too large error, which is not conducive to the use of the battery pack. SUMMARY

[0004] The present application provides a method for estimating SOH value of a battery pack, a battery management system and a computer storage medium to solve the problem of inaccurate SOH value estimation of the existing battery pack.

[0005] To solve the above technical problems, the present application provides a method for estimating SOH value of a battery pack, comprising: obtaining the cumulative discharge capacity of the battery pack since it is put into operation; obtaining the first SOH value of the battery pack according to the cumulative discharge capacity; obtaining the actual battery capacity of the battery pack under the condition that the battery pack is from full state to static state; obtaining the second SOH value of the battery pack according to the actual battery capacity; comparing the first SOH value and the second SOH value; if the first SOH value is greater than the second SOH value, taking the second SOH value as the estimated SOH value; updating the current SOH value of the battery pack according to the estimated SOH value.

[0006] In one embodiment, the SOH value estimation method further comprises: if the first SOH value is less than the second SOH value, comparing the current SOH value and the first SOH value; taking the smaller one of the current SOH value and the first SOH value as the estimated SOH value.

[0007] In one embodiment, obtaining the first SOH value of the battery pack based on the cumulative discharge capacity includes: calculating the quotient of the cumulative discharge capacity and the rated battery capacity of the battery pack to obtain the number of discharge cycles; and obtaining the SOH value corresponding to the number of discharge cycles from a preset table of the number of cycles and SOH values ​​to use as the first SOH value.

[0008] In one embodiment, obtaining the actual battery capacity of the battery pack when the battery pack is in a fully charged state to a resting state includes: obtaining the actual battery capacity of the battery pack when the battery pack is discharged from a fully charged state to a state where the current SOC value of the battery pack is below a first preset value and the battery pack is in a resting state for a first time.

[0009] In one embodiment, the SOH value estimation method further includes: obtaining the cumulative charging ampere-hours of the battery pack when the battery pack changes from a fully charged state to a resting state; and when the cumulative charging ampere-hours is less than a preset proportion of the rated battery capacity, performing the step of obtaining a second SOH value of the battery pack based on the actual battery capacity.

[0010] In one embodiment, obtaining the actual battery capacity of the battery pack when the battery pack is transitioning from a fully charged state to a resting state includes: obtaining the cumulative discharge ampere-hours of the battery pack when the battery pack is transitioning from a fully charged state to a resting state; dividing the cumulative discharge ampere-hours by the difference between a second preset value and the current SOC value of the battery pack to obtain the actual battery capacity; and obtaining the second SOH value of the battery pack based on the actual battery capacity includes: calculating the quotient of the actual battery capacity and the rated battery capacity as the second SOH value.

[0011] In one embodiment, the SOH value estimation method further includes: statically correcting the current SOC value when the battery pack changes from a fully charged state to a resting state to obtain a corrected SOC value; dividing the cumulative discharge ampere-hours by the difference between a second preset value and the current SOC value of the battery pack to obtain the actual battery capacity, including: dividing the cumulative discharge ampere-hours by the difference between the second preset value and the corrected SOC value to obtain the actual battery capacity.

[0012] In one embodiment, the SOH value estimation method further includes: detecting the lowest temperature of the battery pack; if the lowest temperature is greater than or equal to a preset temperature, triggering a step of obtaining the actual battery capacity of the battery pack during the period from a fully charged state to a resting state.

[0013] In one embodiment, updating the current SOH value based on the estimated SOH value includes: calculating the estimated battery capacity of the battery pack based on the estimated SOH value; updating the current battery capacity with the average of the estimated battery capacity and the current battery capacity; and calculating the SOH value based on the updated current battery capacity to update the current SOH value.

[0014] To address the aforementioned technical problems, this application provides a battery management system, comprising: a processor and a memory; the memory is used to store at least one executable instruction, and the processor is used to execute the executable instruction to implement the method described above.

[0015] To address the aforementioned technical problems, this application provides a computer storage medium storing at least one executable instruction, which, when executed, implements the method described above.

[0016] Unlike existing technologies, the SOH (State of Health) estimation method for battery packs in this application first calculates a first SOH value based on cumulative discharge, specifically by obtaining the cumulative discharge capacity of the battery pack since its operation. Then, during the process of the battery pack transitioning from a fully charged state to a resting state, a second SOH value is calculated, i.e., obtaining the second SOH value under relatively stable conditions. This second SOH value is then used to correct the current SOH value. Specifically, during the transition from a fully charged state to a resting state, the actual battery capacity of the battery pack is obtained, and the second SOH value is obtained based on this actual capacity. The first and second SOH values ​​are compared; if the first SOH value is greater than the second SOH value, the second SOH value is used as the estimated SOH value. Finally, the current SOH value of the battery pack is updated based on the estimated SOH value. This application utilizes the second SOH value, which can be accurately estimated under relatively stable conditions, to correct the SOH value of the battery pack, thereby achieving accurate SOH value estimation and enabling efficient battery pack management. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the present disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0018] Figure 1 This is a flowchart illustrating an embodiment of the SOH value estimation method for the battery pack of this application;

[0019] Figure 2 This is a schematic diagram of a virtual module structure of an embodiment of the battery management system of this application;

[0020] Figure 3 This is a schematic diagram of the structure of an embodiment of the battery management system of this application;

[0021] Figure 4 This is a schematic diagram of the main control chip in one embodiment of the battery management system of this application;

[0022] Figure 5This is a schematic diagram of the structure of an embodiment of the computer storage medium of this application. Detailed Implementation

[0023] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0024] This application is used to estimate the State of Health (SOH) value of a battery pack to determine its health status. Specifically, this application first calculates a first SOH value based on the cumulative discharge capacity, i.e., the cumulative discharge capacity of the battery pack since it began operation. Obviously, the higher the cumulative discharge capacity, the lower the SOH value. Then, the SOH value is corrected by considering the actual capacity of the battery pack. Specifically, this is done by obtaining the actual capacity of the battery pack when it transitions from a fully charged state to a resting state, i.e., when the battery pack is in a relatively stable state, and then calculating a second SOH value based on the actual capacity. If the second SOH value is relatively low, it is used as the estimated SOH value, and the current SOH value of the battery pack is updated based on the estimated SOH value.

[0025] This application combines the cumulative discharge capacity and the actual capacity to calculate the SOH value, and further corrects the calculation based on the actual capacity when the battery is in a relatively stable state, thus obtaining a more accurate SOH value. For details of the SOH value estimation method in this application, please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the SOH value estimation method for the battery pack of this application. This embodiment includes the following steps.

[0026] S101: Obtain the cumulative discharge capacity of the battery pack since it started operating.

[0027] Once the battery pack is installed in the device, the device begins managing the battery pack, accumulating its discharge capacity to obtain the cumulative discharge capacity since the battery pack began operation. Although a battery pack generally consists of multiple batteries, in this embodiment, the battery pack can also be a single battery; that is, the SOH value estimation method of this embodiment can also be used for a single battery.

[0028] Optionally, the SOH estimation method for the battery pack in this embodiment can be executed in response to an external estimation command. In other possible implementations, the SOH estimation method for the battery pack in this embodiment can also be executed once every preset time period. The preset time period is not limited, and can be, for example, 100ms or 200ms.

[0029] S102: The first SOH value of the battery pack is obtained based on the cumulative discharge capacity.

[0030] The cumulative discharge capacity reflects the usage status of the battery pack, which in turn reflects the degree of degradation and health status of the battery pack. Therefore, the SOH value of the battery pack can be obtained using the cumulative discharge capacity.

[0031] One approach used in this step is to equate the cumulative discharge capacity to the number of discharge cycles of the battery pack. That is, the quotient of the cumulative discharge capacity and the rated battery capacity of the battery pack is calculated to obtain the number of discharge cycles. Then, based on the number of discharge cycles, the SOH value corresponding to the number of discharge cycles is obtained as the first SOH value. In this embodiment, a correspondence table between the number of cycles and the SOH value is preset, and the SOH value is obtained based on this correspondence table. In other embodiments, the SOH value can also be obtained by calculating the number of cycles according to a preset calculation function.

[0032] The specific correspondence between the number of cycles and the SOH value in this embodiment is as follows: when the number of discharge cycles is less than or equal to 50, the SOH value remains at 100%; when the number of discharge cycles is greater than 50, the SOH value begins to decrease, and the rated capacity of the battery is 280Ah.

[0033]

[0034] Other methods can also be used in this step, such as weighting the cumulative discharge capacity to obtain the cumulative discharge ampere-hours. Different cumulative discharge ampere-hours correspond to different SOH values.

[0035] The SOH value estimation method in this embodiment is based on the battery management program. The calculation of the first SOH value in this step can be performed periodically in the battery management program, for example, once every 100ms. The specific calculation cycle can be set in conjunction with the overall battery management scheme, such as the calculation cycle of other parameter values. Those skilled in the art can also set it according to the actual situation.

[0036] S103: Obtain the actual battery capacity of the battery pack when the battery pack changes from a fully charged state to a resting state.

[0037] The actual battery capacity of a battery pack can provide a relatively intuitive reflection of its degradation level and health status. Therefore, the SOH value of the battery pack can be calculated using the actual battery capacity obtained when the battery pack is in a fully charged state and then in a resting state. This allows for the subsequent determination of an estimated SOH value by combining the SOH value calculated from the actual battery capacity and the SOH value calculated from the cumulative discharge capacity.

[0038] Optionally, the actual battery capacity of the battery pack can be obtained when the battery pack is discharged from a fully charged state to a state of SOC value below a first preset value, and the battery pack remains in a static state.

[0039] The first preset value can be set according to the actual situation, and there is no restriction here. For example, it can be 20%, 30%, or 50%.

[0040] In addition, the quiescent state can refer to the state in which the battery pack meets a current requirement of less than a preset amount. The preset amount can be set according to the actual situation and is not limited here, for example, 0.1C or 0.5C.

[0041] The battery pack remaining in a static state can refer to the battery pack remaining in a static state for a period exceeding a certain time after discharging to a state where the SOC value falls below a first preset value. This first time can be set according to actual conditions and is not limited here; for example, it could be 1 hour or 1.5 hours. Alternatively, the battery pack remaining in a static state can refer to the battery pack remaining in a static state until a static SOC correction is triggered after discharging to a state where the SOC value falls below the first preset value. Existing static correction methods can be used for SOC correction, which will not be elaborated here. For example, when the battery pack is in a static mode (which can be understood as the battery pack being in an unloaded state), the OCV table is consulted, and the corresponding SOC value at voltage and temperature is obtained based on the OCV curve. Then, the SOC correction begins at the next load time, with the ampere-hour integral smoothly correcting to the target value at a certain rate, either accelerating or decelerating.

[0042] Optionally, when the battery pack is discharged from a fully charged state to a state of SOC value below a first preset value, and the battery pack remains in a static state, the step of obtaining the actual battery capacity of the battery pack may include: obtaining the cumulative discharge ampere-hours of the battery pack during the process of discharging from a fully charged state to a state of SOC value below a first preset value and then remaining in a static state; dividing the cumulative discharge ampere-hours by the difference between a second preset value and the SOC value to obtain the actual battery capacity, wherein the second preset value may be 100% or 95%, etc.

[0043] Optionally, the "SOC value" in "the difference between the cumulative discharge ampere-hours divided by 100% and the SOC value" can be the current SOC value of the battery pack.

[0044] Alternatively, the "SOC value" in "the difference between the cumulative discharge ampere-hours divided by 100% and the SOC value" can be the SOC correction value obtained after statically correcting the current SOC value of the battery pack. For example, suppose that the static SOC correction of the battery pack is triggered while the battery pack is continuously in a static state. When the battery pack is discharged from a fully charged state to a SOC value below a first preset value, and the battery pack is continuously in a static state, the step of obtaining the actual battery capacity of the battery pack may include: obtaining the cumulative discharge ampere-hours of the battery pack during the process of discharging from a fully charged state to a SOC value below the first preset value and then continuously in a static state; dividing the cumulative discharge ampere-hours by 100% and the difference between the statically corrected SOC correction value to obtain the actual battery capacity.

[0045] S104: The second SOH value of the battery pack is obtained based on the actual battery capacity.

[0046] Optionally, the quotient of the actual battery capacity and the rated battery capacity can be calculated as a second SOH value.

[0047] Of course, other methods can also be used in this step, such as determining the second SOH value corresponding to the actual battery capacity based on the correspondence between the actual battery capacity or the range of the actual battery capacity and the second SOH value.

[0048] Furthermore, during the process of the battery pack changing from a fully charged state to a resting state, there may be a charging situation. This application can determine whether to execute step S104 based on the specific charging information during the process of changing from a fully charged state to a resting state.

[0049] For example, the cumulative charging ampere-hours of the battery pack can be obtained during the process of the battery pack changing from a fully charged state to a resting state. If the cumulative charging ampere-hours of the battery pack are less than a preset proportion of the rated battery capacity, then step S104 is executed. The preset proportion can be set according to the actual situation and is not limited here. For example, it can be 1 / 2 or 1 / 3.

[0050] To facilitate confirmation that the cumulative charging amp-hours of the battery pack are less than a preset proportion of the rated battery capacity during the process of the battery pack transitioning from a fully charged state to a resting state, the total charging amp-hours can be backed up when the battery pack is in the fully charged state. Then, the latest backed-up total charging amp-hours is subtracted from the total charging amp-hours updated due to charging during the transition from a fully charged state to a resting state to obtain the cumulative charging amp-hours of the battery pack during this process. The aforementioned total charging amp-hours can be understood as the cumulative charging amp-hours of the battery pack since it began operation.

[0051] Additionally, before step S103, the lowest temperature of the battery pack can be detected. If the lowest temperature of the battery pack is greater than or equal to a preset temperature, step S103 is triggered to calculate a more accurate second SOH value at an appropriate temperature. The preset temperature can be 0℃ to 5℃, specifically 0℃, etc. Of course, in other embodiments, the lowest temperature of the battery pack may not be detected before step S103; that is, step S103 is triggered regardless of whether the lowest temperature of the battery pack is greater than or equal to 0℃.

[0052] S105: Compare the first SOH value and the second SOH value.

[0053] After calculating the first SOH value and the second SOH value based on the above steps, the first SOH value and the second SOH value can be compared so that the estimated SOH value can be obtained based on the comparison result of the first SOH value and the second SOH value.

[0054] In one feasible approach, the smaller of the first SOH value and the second SOH value can be used as the estimated SOH value. For example, if the first SOH value is greater than the second SOH value, the second SOH value is used as the estimated SOH value; if the first SOH value is less than the second SOH value, the first SOH value is used as the estimated SOH value.

[0055] In another possible implementation, if the first SOH value is greater than the second SOH value, proceed to step S106, that is, use the second SOH value as the estimated SOH value; if the first SOH value is less than the second SOH value, proceed to step S107, that is, compare the current SOH value and the first SOH value, and use the smaller of the current SOH value and the first SOH value as the estimated SOH value.

[0056] S106: Use the second SOH value as the estimated SOH value.

[0057] If the first SOH value is greater than the second SOH value, then the second SOH value is used as the estimated SOH value.

[0058] S107: Compare the current SOH value with the first SOH value, and take the smaller of the current SOH value and the first SOH value as the estimated SOH value.

[0059] If the first SOH value is less than the second SOH value, the current SOH value and the first SOH value can be compared, and the smaller of the two values ​​can be used as the estimated SOH value.

[0060] Optionally, the SOH value estimation method for the battery pack in this application may refer to a method that calculates an estimated SOH value and updates the current SOH value based on the estimated SOH value; based on this, after executing steps S106 and S107, the process proceeds to step S108. In other possible implementations, the SOH value estimation method for the battery pack in this application may refer only to a method that calculates an estimated SOH value.

[0061] S108: Update the current SOH value of the battery pack based on the estimated SOH value.

[0062] This step S108 specifically includes the following steps:

[0063] a. Calculate the estimated battery capacity of the battery pack based on the estimated SOH value.

[0064] After calculating the estimated SOH value of the battery pack through the above steps, the estimated battery capacity of the battery pack can be calculated based on the estimated SOH value.

[0065] Optionally, the estimated battery capacity of the battery pack can be calculated based on the estimated state of equilibrium (SOH) value and the rated battery capacity of the battery pack. For example, the estimated battery capacity can be obtained by multiplying the estimated SOH value and the rated battery capacity of the battery pack.

[0066] b. Update the current battery capacity using the average of the estimated battery capacity and the current battery capacity.

[0067] After calculating the estimated battery capacity of the battery pack, the current battery capacity can be updated using the average of the estimated battery capacity and the current battery capacity.

[0068] c. Calculate the SOH value based on the updated current battery capacity to update the current SOH value.

[0069] After determining the updated current battery capacity based on step S109, the current SOH value can be updated based on the updated current battery capacity.

[0070] Optionally, the updated current SOH value can be calculated based on the updated current battery capacity and the rated battery capacity of the battery pack. For example, the updated current SOH value can be obtained by calculating the quotient of the updated current battery capacity and the rated battery capacity of the battery pack.

[0071] In this embodiment, the present application calculates a first SOH value based on the cumulative discharge status; and when the battery pack changes from a fully charged state to a resting state, the actual capacity of the battery pack is obtained, and a second SOH value is calculated based on the actual capacity; if the second SOH value is relatively small, the second SOH value is used as an estimated SOH value. In this way, the present application combines the cumulative discharge capacity and the actual capacity to calculate the SOH value, thereby using the actual capacity when the battery state is relatively stable for correction calculation, and a more accurate SOH value can be obtained.

[0072] Please see Figure 2 , Figure 2 This is a schematic diagram of a virtual module structure of an embodiment of the battery management system of this application. The battery management system 20 of this application includes a first SOH value calculation module 21, a second SOH value calculation module 22, and an estimated SOH value calculation module 23.

[0073] The first SOH value calculation module 21 is used to obtain the cumulative discharge capacity of the battery pack since it started working; and to obtain the first SOH value of the battery pack based on the cumulative discharge capacity.

[0074] The second SOH value calculation module 22 is used to obtain the actual battery capacity of the battery pack when the battery pack changes from a fully charged state to a resting state; and to obtain the second SOH value of the battery pack based on the actual battery capacity.

[0075] The SOH value estimation module 23 is used to compare the first SOH value and the second SOH value; if the first SOH value is greater than the second SOH value, then the second SOH value is used as the estimated SOH value.

[0076] Optionally, the SOH value estimation module 23 can also be used to compare the current SOH value and the first SOH value if the first SOH value is less than the second SOH value; and take the smaller of the current SOH value and the first SOH value as the estimated SOH value.

[0077] Optionally, the first SOH value calculation module 21 can be used to calculate the quotient of the cumulative discharge capacity and the rated battery capacity of the battery pack to obtain the number of discharge cycles; based on a preset correspondence table of the number of cycles and SOH values, the SOH value corresponding to the number of discharge cycles is used as the first SOH value.

[0078] Optionally, the second SOH value calculation module 22 can be used to obtain the actual battery capacity of the battery pack when the battery pack is discharged from a fully charged state to a state where the SOC value is below a first preset value and the battery pack is in a static state for a first time.

[0079] Optionally, the second SOH value calculation module 22 can be used to obtain the cumulative charging ampere-hours of the battery pack when the battery pack is in a state of being fully charged to a state of being at rest; when the cumulative charging ampere-hours is less than a preset proportion of the rated battery capacity, the step of obtaining the second SOH value of the battery pack based on the actual battery capacity is executed.

[0080] Optionally, the second SOH value calculation module 22 can be used to obtain the cumulative discharge ampere-hours of the battery pack when the battery pack is in a state of being fully charged to a state of being at rest; divide the cumulative discharge ampere-hours by the difference between 100% and the SOC value to obtain the actual battery capacity; and calculate the quotient of the actual battery capacity and the rated battery capacity as the second SOH value.

[0081] Optionally, the second SOH value calculation module 22 can be used to statically correct the SOC value when the battery pack changes from a fully charged state to a static state, and obtain the SOC correction value; the actual battery capacity is obtained by dividing the cumulative discharge ampere-hours by 100% and the difference between the SOC correction value and the correction value.

[0082] Optionally, the second SOH value calculation module 22 can be used to detect the lowest temperature of the battery pack. If the lowest temperature is greater than or equal to 0°C, the step of obtaining the actual battery capacity of the battery pack is triggered when the battery pack changes from a fully charged state to a stationary state.

[0083] Optionally, the battery management system may include a State of Health (SOH) update module 24. The SOH update module 24 is used to calculate the estimated battery capacity of the battery pack based on the estimated SOH value; update the current battery capacity with the average of the estimated battery capacity and the current battery capacity; and calculate the SOH value based on the updated current battery capacity to update the current SOH value.

[0084] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of an embodiment of the battery management system of this application. The battery management system 30 of this application includes a memory 31 and a processor 32. The memory 31 stores at least one executable instruction, and the processor 32 is used to execute the executable instruction to implement the method provided by any embodiment of the method of this application and any non-conflicting combination thereof.

[0085] A battery management system (BMS) is a system for monitoring and managing batteries. The BMS can be applied to electric vehicles, underwater robots, and other applications.

[0086] Memory 31 is used to store executable instructions and data required for the processor 32 to run.

[0087] Processor 32 may be referred to as CPU (Central Processing Unit). Processor 22 may be an integrated circuit chip with signal processing capabilities. Processor 22 may also be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component. The general-purpose processor may be a microprocessor, or processor 22 may be any conventional processor, etc.

[0088] Please see Figure 4 , Figure 4 This is a schematic diagram of the main control board 40 in one embodiment of the battery management system of this application.

[0089] The main control board 40 includes a main control chip 41, at least one voltage detection chip 42, and at least one battery pack 43.

[0090] The main control chip 41 is connected to at least one voltage detection chip 42. Each voltage detection chip 42 is connected to at least one battery pack 43. Thus, each voltage detection chip 42 can detect relevant information about its corresponding battery pack 43 and estimate the state of harm (SOH) value of the battery pack 43 based on this information.

[0091] Optionally, the voltage detection chip 42 can be a dedicated battery management system chip such as the ADBMS6815. The voltage detection chip 42 can support voltage measurement of a single series-connected battery cell for up to 12 seconds. The total measurement error of the voltage detection chip 42 over its lifespan is within 1.5mV. The voltage detection chip 42 also supports hot-swapping, has redundant voltage measurement functions and rich fault diagnosis capabilities, can adopt a 16-bit ADC architecture, can be designed with different noise filtering configurations, and can also support programmable PWM equalization control, with internal equalization supporting up to 300mA.

[0092] Optionally, the voltage detection chip 42 can also support daisy-chain communication. Specifically, the voltage detection chip 42 can support various methods such as capacitor daisy-chain and transformer daisy-chain, which enables the communication of the voltage detection chip 42 to have good anti-interference and low EMI, and can also support a communication rate of 2Mbps.

[0093] For example, the voltage detection chips 42 are cascaded using a transformer daisy-chain communication method. For example, for a 36S single cell, three voltage detection chips 42 can be used to form a daisy chain; for a 24S single cell, two voltage detection chips 42 can be used to form a daisy chain.

[0094] The main control board 40 may also include at least one temperature measuring circuit 44, and at least one voltage detection chip 42 is connected to at least one temperature measuring circuit 44 in a one-to-one correspondence. In this way, each voltage detection chip 42 can detect the temperature measurement information of the temperature measuring circuit 44 connected to it, and make an accurate estimate of the SOH value of the battery pack 43 based on the relevant information of the battery pack 43 and the temperature measurement information.

[0095] Additionally, the temperature sensing circuit 44 may include a voltage divider resistor and a temperature sensing resistor. The voltage divider resistor and the temperature sensing resistor are connected in series between the power supply and ground of the temperature sensing circuit 44. The voltage detection chip 42, connected to the temperature sensing resistor, can acquire the voltage across the temperature sensing resistor, calculate the resistance value of the temperature sensing resistor, and then determine the temperature value corresponding to the resistance value of the temperature sensing resistor based on the correlation between the resistance value and temperature.

[0096] The resistance value of the voltage divider resistor can be set according to the characteristics of the temperature sensing resistor. For example, if the temperature sensing resistor is 10K, then the voltage divider resistor can also be 10K.

[0097] The voltage detection chip 42, connected to the temperature sensing resistor, can provide multiple GPIO ports for detecting the voltage division of the temperature sensing resistor. For example, assuming the voltage detection chip 42 is an ADBMS6815, it can provide seven GPIO ports for detecting analog voltage. Furthermore, the voltage detection chip 42 connected to the temperature sensing resistor can provide a reference voltage terminal for powering the temperature sensing circuit 44.

[0098] Based on the characteristic that the temperature measuring circuit 44 has a certain detection temperature range (e.g., -40℃ to 125℃), in the software design, if the calculated resistance value is very large, it is considered that the corresponding temperature measuring circuit 44 has a broken wire fault; if the calculated resistance value is very small, it is considered that the corresponding temperature measuring circuit 44 has a short circuit fault.

[0099] The main control board 40 may also include a temperature equalization circuit. This temperature equalization circuit is used to measure the temperature equalization of the main control board 40 in order to perform temperature management for battery equalization.

[0100] Please see Figure 5 , Figure 5This is a schematic diagram of the structure of a computer storage medium in an embodiment of this application. The computer storage medium 50 in this embodiment stores executable instructions 51. When executed, these executable instructions 51 implement the methods provided in any embodiment of the method described above, as well as any non-conflicting combination thereof. The executable instructions 51 can form a program file and be stored in the storage medium 50 as a software product, causing a computing device or processor to execute all or part of the steps of the methods in various embodiments of this application. The aforementioned storage medium 50 includes various media capable of storing program code, such as read-only memory (ROM) and random access memory (RAM), or devices such as computers, cloud servers, and automobiles.

[0101] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural or procedural changes made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A method for estimating the SOH value of a battery pack, characterized in that, The method for estimating the SOH value includes: Obtain the cumulative discharge capacity of the battery pack since it began operating; The first SOH value of the battery pack is obtained based on the cumulative discharge capacity. The actual battery capacity of the battery pack is obtained when the battery pack is in a state of being fully charged and then in a state of being at rest. The second SOH value of the battery pack is obtained based on the actual battery capacity. Compare the first SOH value and the second SOH value; If the first SOH value is greater than the second SOH value, then the second SOH value is used as the estimated SOH value; The current SOH value of the battery pack is updated based on the estimated SOH value; If the first SOH value is less than the second SOH value, then compare the current SOH value with the first SOH value; The smaller of the current SOH value and the first SOH value is taken as the estimated SOH value.

2. The SOH value estimation method according to claim 1, characterized in that, The step of obtaining the first SOH value of the battery pack based on the cumulative discharge capacity includes: Calculate the quotient of the cumulative discharge capacity and the rated battery capacity of the battery pack to obtain the number of discharge cycles; From the preset table of cycle number and SOH value correspondence, obtain the SOH value corresponding to the discharge cycle number, and use it as the first SOH value.

3. The SOH value estimation method according to claim 1, characterized in that, The step of obtaining the actual battery capacity of the battery pack when the battery pack is in a state of transition from a fully charged state to a resting state includes: When the battery pack is discharged from a fully charged state to a state where the current SOC value of the battery pack is below a first preset value, and the battery pack is in a static state for a first time, the actual battery capacity of the battery pack is obtained.

4. The SOH value estimation method according to claim 1, characterized in that, The SOH value estimation method further includes: When the battery pack is in a state of being fully charged to a state of being at rest, the cumulative charging ampere-hours of the battery pack are obtained; When the cumulative charging ampere-hours are less than a preset proportion of the rated battery capacity, the step of obtaining the second SOH value of the battery pack based on the actual battery capacity is performed.

5. The method for estimating SOH value according to any one of claims 1-4, characterized in that, Obtaining the actual battery capacity of the battery pack when it is in a state of complete charge to a resting state includes: When the battery pack is in a state of being fully charged to a state of being at rest, the cumulative discharge ampere-hours of the battery pack are obtained; The actual battery capacity is obtained by dividing the cumulative discharge ampere-hours by the difference between the second preset value and the current SOC value of the battery pack. The step of obtaining the second SOH value of the battery pack based on the actual battery capacity includes: The quotient of the actual battery capacity and the rated battery capacity is calculated and used as the second SOH value.

6. The SOH estimation method according to claim 5, characterized in that, The SOH value estimation method also includes: When the battery pack changes from a fully charged state to a resting state, the current SOC value is statically corrected to obtain a corrected SOC value. The step of dividing the cumulative discharge ampere-hours by the difference between the second preset value and the current SOC value of the battery pack to obtain the actual battery capacity includes: The actual battery capacity is obtained by dividing the cumulative discharge ampere-hours by the difference between the second preset value and the SOC correction value.

7. The SOH estimation method according to any one of claims 1-4, characterized in that, The SOH value estimation method also includes: The lowest temperature of the battery pack is detected. If the lowest temperature is greater than or equal to a preset temperature, the step of obtaining the actual battery capacity of the battery pack when the battery pack changes from a fully charged state to a resting state is triggered.

8. The SOH estimation method according to any one of claims 1-4, characterized in that, Updating the current SOH value of the battery pack based on the estimated SOH value includes: Calculate the estimated battery capacity of the battery pack based on the estimated SOH value; The current battery capacity is updated using the average of the estimated battery capacity and the current battery capacity; The SOH value is calculated based on the updated current battery capacity to update the current SOH value.

9. A battery management system, characterized in that, The battery management system includes: a processor and a memory; The memory is used to store at least one executable instruction, and the processor is used to execute the executable instruction to implement the method as described in any one of claims 1-8.

10. A computer storage medium, characterized in that, The computer storage medium stores at least one executable instruction, which, when executed, implements the method as described in any one of claims 1-8.

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