Method for estimating SOC of battery and battery management system using same

Abstract

The present disclosure relates to a method for estimating the SOC of a battery and a battery management system using same. The SOC estimation method includes the steps of: monitoring current data for a plurality of batteries connected in series; monitoring a plurality of pieces of voltage data for the plurality of batteries; calculating an average voltage for the plurality of batteries by using the plurality of pieces of voltage data; calculating a first SOC of the plurality of batteries; and estimating a second SOC, which is a value corrected from the first SOC, on the basis of the current data, the average voltage, and the first SOC, wherein the plurality of pieces of voltage data correspond to the plurality of batteries, respectively.

Description

Battery SOC estimation method and battery management system using the same

[0001] The present disclosure relates to a method for estimating the SOC of a battery and a battery management system using the same.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] SOC (State of Charge) refers to the state of charge of a secondary battery. For example, a 70% SOC indicates that the remaining capacity of the secondary battery is 70% of its total capacity. Accurately estimating a secondary battery's SOC can be a critical factor in its management. Currently, representative SOC measurement methods include chemical measurement, voltage measurement, current integration, and pressure measurement. However, each measurement method has its own inherent errors, which may necessitate efforts to compensate for the SOC.

[0004] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0005] The present disclosure provides a method for estimating the SOC of a battery and a battery management system using the same to solve the above-mentioned problems.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] A method for estimating SOC according to some embodiments of the present disclosure for solving a technical problem may include a step of monitoring current data for a plurality of batteries connected in series, a step of monitoring a plurality of voltage data for the plurality of batteries, a step of calculating an average voltage for the plurality of batteries using the plurality of voltage data, a step of calculating a first SOC for the plurality of batteries, and a step of estimating a second SOC, which is a value corrected from the first SOC, based on the current data, the average voltage, and the first SOC. Each of the plurality of voltage data may correspond to each of the plurality of batteries.

[0008] According to some embodiments of the present disclosure, the step of estimating the second SOC may include the steps of calculating a first remaining capacity for the plurality of batteries based on the first SOC, calculating a second remaining capacity for the plurality of batteries based on an average voltage, calculating a third remaining capacity for the plurality of batteries based on the current data, the first remaining capacity, and the second remaining capacity, and calculating the second SOC based on the third remaining capacity.

[0009] According to some embodiments of the present disclosure, the first residual capacity can be calculated by mathematical expression 1.

[0010] [Mathematical Formula 1]

[0011]

[0012] According to some embodiments of the present disclosure, the step of calculating the second residual capacity may include the step of calculating the second residual capacity from an average voltage based on an SOC-voltage table.

[0013] According to some embodiments of the present disclosure, the step of calculating the third residual capacity may include calculating the third residual capacity by adding a current integration value to the first residual capacity in response to the current data being monitored.

[0014] According to some embodiments of the present disclosure, the step of calculating the third residual capacity may include the step of determining a stable state of the battery in response to the current data not being monitored.

[0015] According to some embodiments of the present disclosure, the step of determining a stable state of the battery may include the step of calculating a cumulative average voltage, which is an average value of the average voltage over a certain period of time, and the step of determining that the battery is stabilized when a difference between the average voltage and the cumulative average voltage is less than or equal to a certain value.

[0016] According to some embodiments of the present disclosure, the step of calculating the third residual capacity may include calculating the third residual capacity by Equation 2 in response to determining that the battery is stabilized.

[0017] [Equation 2]

[0018]

[0019] According to some embodiments of the present disclosure, a certain value can be calculated by Equation 3, wherein the value of a is less than the capacity of the battery, and the value of b is less than the value of a.

[0020] [Equation 3]

[0021]

[0022] According to some embodiments of the present disclosure, the second SOC can be calculated by dividing the third remaining capacity by the capacity of the battery.

[0023] According to some embodiments of the present disclosure, the method may further include a step of transmitting a control signal for managing the battery based on the estimated second SOC.

[0024] According to some embodiments of the present disclosure, the step of transmitting the control signal may include the step of transmitting the control signal commanding charging of the battery in response to determining that the estimated second SOC is below a predetermined threshold.

[0025] According to some embodiments of the present disclosure for solving the technical problem, a computer program can be stored in a computer-readable recording medium for executing the SOC estimation method according to some embodiments on a computer.

[0026] According to some embodiments of the present disclosure for solving the technical problem, a battery management system includes a memory and at least one processor coupled to the memory and configured to execute at least one computer-readable program included in the memory, wherein the at least one program may include instructions for monitoring current data for a plurality of batteries connected in series, monitoring a plurality of voltage data for the plurality of batteries, calculating an average voltage for the plurality of voltage data, calculating a first SOC of the plurality of batteries, and estimating a second SOC, which is a corrected value from the first SOC, based on the current data, the average voltage, and the first SOC, wherein each of the plurality of voltage data may correspond to a respective one of the plurality of batteries.

[0027] According to some embodiments of the present disclosure, at least one program may further include instructions for calculating a first remaining capacity for the plurality of batteries based on a first SOC, calculating a second remaining capacity for the plurality of batteries based on an average voltage, calculating a third remaining capacity for the plurality of batteries based on the current data, the first remaining capacity, and the second remaining capacity, and calculating a second SOC based on the third remaining capacity.

[0028] According to some embodiments of the present disclosure, at least one program may further include instructions for calculating a second residual capacity from an average voltage based on an SOC-voltage table.

[0029] According to some embodiments of the present disclosure, at least one program may further include instructions for calculating a third residual capacity by adding a current accumulation value to the first residual capacity in response to the current data being monitored.

[0030] According to some embodiments of the present disclosure, at least one program may further include instructions for calculating a cumulative average voltage, which is an average value of the average voltage over a period of time, in response to the current data not being monitored, and determining that the battery is stabilized if a difference between the average voltage and the cumulative average voltage is less than or equal to a predetermined value.

[0031] According to some embodiments of the present disclosure, at least one program may further include instructions for calculating a third remaining capacity by Equation 4 in response to determining that the battery is stabilized.

[0032] [Equation 4]

[0033]

[0034] According to some embodiments of the present disclosure, at least one program may further include instructions for transmitting a control signal for managing the battery based on the estimated second SOC.

[0035] According to some embodiments of the present disclosure, a second SOC, which is a corrected value from the first SOC, can be estimated based on current data for the battery, an average voltage for the battery, and a first SOC of the battery. As a result, an error value of the SOC can be effectively corrected.

[0036] According to some embodiments of the present disclosure, when current data is not monitored, the second SOC can be estimated by determining the battery's stability status and, if the battery is determined to be stabilized, calculating the third remaining capacity. As a result, the SOC error value can be effectively compensated even in situations where current data is not monitored.

[0037] The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary knowledge in the technical field to which the present disclosure belongs (referred to as “ordinary skilled person”) from the description of the claims.

[0038] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0039] FIG. 1 is a diagram illustrating a battery management system according to some embodiments of the present disclosure.

[0040] FIG. 2 is a diagram illustrating a processor according to some embodiments of the present disclosure.

[0041] Figure 3 is a graph to explain that SOC error occurs when current change is not detected.

[0042] FIG. 4 is a graph for explaining the SOC correction result based on the SOC estimation method according to some embodiments of the present disclosure.

[0043] Figure 5 is a graph showing the results of SOC correction considering accumulated current.

[0044] FIG. 6 is a diagram illustrating an example of an SOC-voltage table according to one embodiment of the present disclosure.

[0045] FIG. 7 is a flowchart illustrating a method for estimating SOC of a battery according to some embodiments of the present disclosure.

[0046] FIG. 8 is a flowchart illustrating a method for estimating a second SOC based on current data, average voltage, and first SOC according to some embodiments of the present disclosure.

[0047] FIG. 9 is a flowchart illustrating a method for calculating a third residual capacity based on current monitoring data according to some embodiments of the present disclosure.

[0048] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0049] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0050] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0051] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0052] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0053] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0054] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0055] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0056] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0057] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, plural expressions include singular expressions unless the context clearly indicates otherwise. When a part of the specification is said to include a component, this does not exclude other components, but rather implies that other components may be included, unless otherwise specifically stated.

[0058] Also, the term 'module' or 'part' used in the specification means a software or hardware component, and the 'module' or 'part' performs certain roles. However, the 'module' or 'part' is not limited to software or hardware. The 'module' or 'part' may be configured to reside on an addressable storage medium and may be configured to execute one or more processors. Thus, as an example, the 'module' or 'part' may include at least one of components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, or variables. The functionality provided within the components and 'modules' or 'parts' may be combined into a smaller number of components and 'modules' or 'parts', or further separated into additional components and 'modules' or 'parts'.

[0059] According to one embodiment of the present disclosure, a 'module' or 'unit' may be implemented as a processor and a memory. 'Processor' should be broadly construed to include a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and the like. In some circumstances, a 'processor' may also refer to an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a field-programmable gate array (FPGA), and the like. A 'processor' may also refer to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors in conjunction with a DSP core, or any other such combination of configurations. In addition, 'memory' should be broadly construed to include any electronic component capable of storing electronic information. 'Memory' may refer to various types of processor-readable media, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, etc. Memory is said to be in electronic communication with the processor if the processor can read information from, and / or write information to, the memory. Memory integrated in a processor is in electronic communication with the processor.

[0060] In the present disclosure, the "system" may include, but is not limited to, at least one of a server device and a cloud device. For example, the system may be comprised of one or more server devices. As another example, the system may be comprised of one or more cloud devices. As yet another example, the system may be configured and operated by a combination of a server device and a cloud device.

[0061] In this disclosure, the sizes and relative sizes of areas depicted in the drawings may be exaggerated for clarity of explanation. In other words, the sizes depicted in the drawings are merely for convenience of understanding and are not intended to be limiting. Furthermore, the flowcharts and descriptions thereof depicted in the drawings are merely examples, and some embodiments may be implemented differently. For example, one or more steps may be omitted, the order of each step may be changed, one or more steps may be performed overlapping, or one or more steps may be repeated multiple times.

[0062] FIG. 1 is a diagram illustrating a battery management system according to some embodiments of the present disclosure. Referring to FIG. 1, the battery management system (100) may include a battery (110), a data measurement unit (120), a processor (130), and a memory (140).

[0063] Battery (110) may refer to a unit battery or a bundle of unit batteries, such as a battery cell, a battery module, or a battery pack. In some embodiments, battery (110) may be a battery cell, a battery module, a battery pack, or a battery rack. For example, if battery (110) is a battery module, battery (110) may include a plurality of battery cells. Furthermore, if battery (110) is a battery module, the plurality of battery cells may be connected in series. Alternatively, the plurality of battery cells may be connected in parallel. In another example, if battery (110) is a battery pack or a battery rack, battery (110) may include a plurality of battery modules and / or a plurality of battery cells. In some embodiments, battery (110) may be a battery module, a battery pack, or a battery rack included in an energy storage system (ESS).

[0064] The battery cell may include a secondary battery capable of being recharged and / or discharged. For example, the battery cell may include a nickel-cadmium battery, a lead-acid battery, a nickel metal hydride (NiMH) battery, a lithium-ion battery, a lithium polymer battery, etc.

[0065] The data measurement unit (120) can monitor the battery (110) to obtain data. For example, the data measurement unit (120) can monitor a plurality of battery cells to obtain current data for the battery (110). Here, if the current flowing through the battery (110) is below a predetermined threshold, the current data for the battery (110) may not be obtained by the data measurement unit (120). As another example, the data measurement unit (120) can monitor a plurality of battery cells to obtain a plurality of voltage data for the plurality of battery cells. In this case, each of the plurality of voltage data may correspond to each of the plurality of battery cells. The data measurement unit (120) can monitor the battery (110) in real time, periodically or aperiodically at predetermined intervals, and transmit the monitoring data for the battery (110) to the processor (130) and / or the memory (140).

[0066] Processor (130) should be broadly construed to include a general purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and the like. In some circumstances, processor (130) may also refer to an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), and the like. Processor (130) may also refer to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors in conjunction with a DSP core, or any other such combination of configurations.

[0067] The processor (130) may be configured to process instructions of a computer program by performing basic arithmetic, logic, and input / output operations. According to some embodiments, the processor (130) may obtain monitoring data of the battery (110) monitored by the data measurement unit (120). In addition, the processor (130) may estimate the SOC of the battery (110) based on the monitoring data of the battery (110). In addition, the processor (130) may determine whether the current data of the battery (110) is monitored by the data measurement unit (120). Here, if the current flowing through the battery (110) is below a predetermined threshold value, the current data for the battery (110) may not be obtained by the data measurement unit (120), and therefore, the processor (130) may determine in this case that the current data of the battery (110) is not monitored by the data measurement unit (120). Additionally, the processor (130) may transmit a control signal for managing the battery (110) based on the estimated SOC of the battery (110). For example, the processor (130) may transmit a control signal to the charging device to command charging of the battery (110) in response to determining that the estimated SOC of the battery (110) is below a predetermined threshold.

[0068] Memory (140) should be broadly construed to include any electronic component capable of storing electronic information. Memory (140) may also refer to various types of processor-readable media, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, and the like. Memory (140) is said to be in electronic communication with the processor (130) if the processor (130) can read information from and / or write information to the memory (140). Memory (140) integrated in the processor (130) is in electronic communication with the processor (130).

[0069] In one embodiment, the memory (140) may include any non-transitory computer-readable recording medium. In one embodiment, the memory (140) may include a permanent mass storage device. As another example, the permanent mass storage device may be a separate permanent storage device distinct from the memory, included in the battery management system (100) or included in a device that may be accessed by the battery management system (100) via wired or wireless means. As another example, the memory (140) may be implemented as included in the processor (130).

[0070] According to one embodiment, the memory (140) may store an operating system and at least one program code (e.g., program code for estimating the SOC of a battery). In addition, the memory (140) may store monitoring data for the battery (110) received from the data measurement unit (120), a plurality of mathematical formulas for estimating the SOC of the battery (110), and at least one SOC-voltage table associated with the capacity of the battery (110).

[0071] FIG. 2 is a diagram illustrating a processor according to some embodiments of the present disclosure. Referring to FIG. 2, the processor (130) may include a data receiving unit (210), an average voltage calculating unit (220), a first SOC calculating unit (230), a second SOC estimating unit (240), and a control unit (250).

[0072] The data receiving unit (210) can receive monitoring data of the monitored battery from the data measuring unit. For example, the data receiving unit (210) can receive current data and voltage data of the monitored battery. Additionally or alternatively, the data receiving unit (210) can receive current data and voltage data of the monitored battery from a memory. The data receiving unit (210) can receive monitoring data of the monitored battery in real time, periodically at predetermined intervals, or aperiodically. The data receiving unit (210) can transmit the received monitoring data of the battery to the average voltage calculating unit (220), the first SOC calculating unit (230), the second SOC estimating unit (240), or the memory.

[0073] The average voltage calculation unit (220) can calculate an average voltage for the battery based on voltage data of the monitored battery. In this case, the battery may be a battery module, a battery pack, or a battery rack. Accordingly, the battery may include multiple battery cells. The average voltage calculation unit (220) can calculate an average voltage for the battery based on each of the plurality of voltage data corresponding to each of the plurality of battery cells. The average voltage calculation unit (220) can transmit the calculated average voltage for the battery to the second SOC estimation unit (240) and / or the memory.

[0074] The first SOC calculation unit (230) can calculate the first SOC of the battery based on the monitoring data of the battery. The first SOC calculation unit (230) can calculate the first SOC of the battery based on a voltage measurement method, a current integration method, etc. In addition, the first SOC calculation unit (230) can calculate the first SOC of the battery by utilizing an Extended Kalman Filter (EFK) algorithm. Here, the Extended Kalman Filter algorithm may be a technique for estimating the SOC of the battery based on an equivalent circuit model (ECM) that implements the electrical characteristics of the battery through an equivalent circuit. The first SOC calculation unit (230) can transmit the calculated first SOC of the battery to the second SOC estimation unit (240) and / or a memory.

[0075] The second SOC estimation unit (240) can estimate the second SOC, which is a corrected value from the first SOC, based on the monitoring data of the battery, the average voltage of the battery, and the first SOC of the battery. Additionally, the second SOC estimation unit (240) can utilize a plurality of mathematical equations and an SOC-voltage table stored in the memory to estimate the second SOC of the battery. The second SOC estimation unit (240) can transmit the estimated second SOC of the battery to the control unit (250) and / or the memory.

[0076] In one embodiment, the second SOC estimation unit (240) may calculate a first remaining capacity for the battery based on the first SOC of the battery. Here, the first remaining capacity for the battery may be calculated by the following mathematical equation.

[0077] [Mathematical formula]

[0078]

[0079] In one embodiment, the second SOC estimation unit (240) may calculate a second remaining capacity for the battery based on an average voltage for the battery. Here, the second SOC estimation unit (240) may calculate the second remaining capacity of the battery from the average voltage for the battery based on an SOC-voltage table associated with the capacity of the battery. Here, the SOC-voltage table may refer to a table that pre-organizes the relationship between the SOC of the battery and the battery voltage in units of 5% of SOC. The relationship between the SOC of the battery and the battery voltage may vary depending on the total capacity of the battery. Accordingly, the SOC-voltage table may vary depending on the total capacity of the battery. The second SOC estimation unit (240) may extract an SOC matching thereto from the average voltage for the battery based on the SOC-voltage table stored in the memory, and multiply the extracted SOC by the total capacity of the battery to calculate the second remaining capacity of the battery. For example, if the average voltage for the battery is 3,959 mV, the second SOC estimation unit (240) can estimate that the SOC is 90% by referring to the SOC-voltage table, and can calculate the second remaining capacity as 102,600 mAh by multiplying the total capacity of the battery, 114 Ah. An SOC-voltage table according to one embodiment of the present disclosure is described below with reference to FIG. 6.

[0080] In one embodiment, the second SOC estimation unit (240) can calculate a third remaining capacity of the battery based on monitoring data of the battery, a first remaining capacity of the battery, and a second remaining capacity of the battery.

[0081] In one embodiment, the second SOC estimation unit (240) can determine whether the current data of the battery is monitored by the data measurement unit.

[0082] The second SOC estimation unit (240) can calculate the third remaining capacity of the battery by adding the current integration value to the first remaining capacity of the battery in response to determining that the current data of the battery is monitored. Here, the current integration value can be calculated by multiplying the current data of the battery measured by the data measurement unit by the measurement time. For example, if the current data of the battery measured for 1 second is 40A, the current integration value is 11mAh. can be calculated as

[0083] The second SOC estimation unit (240) may, in response to determining that the current data of the battery is not being monitored, calculate a cumulative average voltage, which is an average value of the average voltage of the battery over a certain period of time, and, if the difference between the average voltage of the battery and the cumulative average voltage is less than a certain value, determine the stability of the battery. In addition, the second SOC estimation unit (240) may, in response to determining that the battery is stabilized, calculate a third remaining capacity of the battery using the following mathematical equation.

[0084] [Mathematical formula]

[0085]

[0086] Here, a certain value can be calculated by the mathematical formula below, and in the mathematical formula below, the value of a may be less than the capacity of the battery, and the value of b may be less than the value of a.

[0087] [Mathematical formula]

[0088]

[0089] In one embodiment, the predetermined value may represent a slope value for correcting the SOC of the battery. For example, the predetermined value may be decreased to perform the SOC correction of the battery at a fast speed. As another example, the predetermined value may be increased to perform the SOC correction of the battery at a slow speed. Accordingly, the slope value for correcting the SOC of the battery may be determined by adjusting the value of b. For example, when the value of b is increased, the slope value for correcting the SOC of the battery may be decreased, thereby performing the SOC correction of the battery at a fast speed, and when the value of b is decreased, the slope value for correcting the SOC of the battery may be increased, thereby performing the SOC correction of the battery at a slow speed.

[0090] The second SOC estimation unit (240) can calculate the second SOC based on the third remaining capacity of the battery. Here, the second SOC estimation unit (240) can calculate the second SOC of the battery by dividing the third remaining capacity of the battery by the maximum capacity of the battery.

[0091] The control unit (250) can receive the second SOC of the battery estimated from the second SOC estimation unit (240). The control unit (250) can transmit a control signal for managing the battery based on the second SOC of the battery received from the second SOC estimation unit (240). Specifically, when the control unit (250) determines that the estimated second SOC of the battery is less than a predetermined threshold value, the control unit (250) can transmit a control signal for commanding charging of the battery to the charging device. For example, when the predetermined threshold value is 50%, the control unit (250) can transmit a control signal for commanding charging of the battery to the charging device when the second SOC of the battery estimated by the second SOC estimation unit (240) is less than 50%.

[0092] In FIG. 2, each component of the processor (130) represents functionally distinct functional elements, and multiple components may be implemented in an integrated manner in an actual physical environment. Alternatively, each component of the processor (130) may be implemented separately from each other in an actual physical environment. Furthermore, although depicted as a single processor in FIG. 2, the processor (130) may be implemented as a multi-core processor including multiple processors (or cores).

[0093] Figure 3 is a graph illustrating that an SOC error occurs when a current change is not detected. Figure 3 shows an SOC-time graph (310), a current-time graph (320), and an average voltage-time graph (330).

[0094] The SOC-time graph (310) illustrated in FIG. 3 shows the SOC value of the battery measured as time elapses from t1 to t5. According to the SOC-time graph (310), it can be confirmed that the SOC value of the battery measured as time elapses from t1 to t5 is maintained at 89.7 (%).

[0095] The current-time graph (320) illustrated in FIG. 3 shows current data of a monitored battery as time elapses from t1 to t5. Here, it can be seen that the current data is monitored aperiodically as time elapses from t1 to t5. For example, it can be seen that the monitored current value maintains a value of 0 except for a few points. This may be because the data measurement unit does not acquire current data for the battery when the current flowing through the battery is below a predetermined threshold. Accordingly, current may still be flowing through the battery even at a time corresponding to a point where the current is indicated as 0 in the current-time graph (320) (in this case, the current flowing through the battery may be below a predetermined threshold).

[0096] The average voltage-time graph (330) illustrated in FIG. 3 illustrates average voltage data of a monitored battery as time elapses from t1 to t5. Here, if the battery includes multiple battery cells, the average voltage data may refer to the average voltage of each voltage data of the multiple battery cells. Alternatively, if the battery is a single battery cell, the average voltage data may refer to the voltage data of the single battery cell itself. Referring to the average voltage-time graph (330), it can be seen that the average voltage for the battery at time t1 is approximately 3918 mV, but at time t5, the average voltage for the battery is approximately 3849 mV. In other words, it can be seen that the average voltage for the battery decreases over time.

[0097] According to the graphs (310, 320, 330) illustrated in FIG. 3, it can be seen that the measured SOC value of the battery maintains a constant value even though the average voltage of the battery decreases over time. This may be because the data measurement unit does not acquire current data for the battery even though current is flowing through the battery. In other words, when a current below a predetermined threshold value flows through the battery, the SOC value of the battery may be measured as a constant value because the current data for the battery is not acquired even though the average voltage of the battery is decreasing. This may cause an error in measuring the SOC value of the battery, and this error may increase over time. For example, the SOC value (312) of the battery measured at time t5 is 89.7%, but the average voltage (332) of the battery monitored at time t5 is approximately 3849 mV, and the value converted to SOC based on the SOC-voltage table may be 78.68%. At time t5, the error in the SOC value is approximately 11%, and this error may increase over time.

[0098] FIG. 4 is a graph illustrating SOC correction results based on a SOC estimation method according to some embodiments of the present disclosure. FIG. 4 illustrates an SOC-time graph (410), a current-time graph (420), and an average voltage-time graph (430).

[0099] The SOC-time graph (410) illustrated in FIG. 4 illustrates the measured SOC value (411) and the corrected SOC value (413) of the battery as time elapses from t1 to t5. The corrected SOC value (413) may correspond to a value estimated by a SOC estimation method according to some embodiments of the present disclosure. According to the SOC-time graph (410), it can be confirmed that the measured SOC value (411) of the battery as time elapses from t1 to t5 is maintained at 89.7 (%). On the other hand, it can be confirmed that the corrected SOC value (413) decreases as time elapses from t1 to t5. Specifically, it can be confirmed that the measured SOC value (412) of the battery at time t5 is 89.7%, whereas the corrected SOC value (414) at time t5 is 78.87%.

[0100] The current-time graph (420) illustrated in FIG. 4 shows current data of a monitored battery as time passes from t1 to t5. This may be identical to the current-time graph (320) described in FIG. 3.

[0101] The average voltage-time graph (430) illustrated in FIG. 4 shows average voltage data of the monitored battery as time passes from t1 to t5. This may be identical to the average voltage-time graph (330) described in FIG. 3.

[0102] Referring to the graphs (410, 420, 430) illustrated in FIG. 4, it can be confirmed that the measured SOC value (411) of the battery maintains a constant value even though the average voltage for the battery decreases. Accordingly, as already confirmed in FIG. 3, the error of the SOC value at time t5 is about 11%. To reduce this error, a SOC estimation method according to some embodiments of the present disclosure can be used. For example, the SOC value (412) of the battery measured at time t5 is 89.7%, but the corrected SOC value (414) at time t5 is 78.87%. As examined in FIG. 3, the average voltage (432) for the battery monitored at time t5, converted to SOC based on the SOC-voltage table, can be 78.68%. Therefore, the error of the SOC value before correction is approximately 11%, and the error of the SOC value after correction is approximately 0.19%, so it can be confirmed that the error value is effectively corrected by the SOC correction.

[0103] Figure 5 is a graph showing the results of SOC correction considering the accumulated current. Figure 5 shows an SOC-time graph (510), a current-time graph (520), and an average voltage-time graph (530).

[0104] The SOC-time graph (510) illustrated in FIG. 5 illustrates the measured SOC value (511) and the corrected SOC value (513) of the battery as time elapses from t1 to t6. The corrected SOC value (513) may correspond to a value estimated by a SOC estimation method according to some embodiments of the present disclosure. Specifically, the corrected SOC value (513) may correspond to a value that estimates the SOC by taking current integration into account when current data is monitored.

[0105] The current-time graph (520) illustrated in FIG. 5 shows current data of a monitored battery as time passes from t1 to t6. Here, the current-time graph from t1 to t5 is the same as that of FIGS. 3 and 4, but it can be seen that current data is monitored as it passes from t5 to t6 (522).

[0106] The average voltage-time graph (530) illustrated in FIG. 5 depicts the average voltage data of the monitored battery as time passes from t1 to t6. Here, the average voltage-time graph from t1 to t5 is identical to that in FIGS. 3 and 4 , but it can be seen that the average voltage decreases and then increases corresponding to the current-time graph (520) as it passes from t5 to t6.

[0107] Referring to the graphs (510, 520, 530) illustrated in FIG. 5, it can be confirmed that the error in the SOC of the battery can be reduced by estimating the SOC by considering the current integration when the current data of the battery is monitored. For example, the SOC value (512) of the battery measured at time t6 after the current data is monitored is 89.7%, but the corrected SOC value (514) at time t6 can be confirmed to be 80.73%. In addition, the average voltage (532) for the battery monitored at time t6 after the current data is monitored is approximately 3871 mV, and the value converted to SOC based on the SOC-voltage table can be 81.05%. Therefore, the error of the SOC value before correction at time t6 is 8.65%, and the error of the SOC value after correction is 0.32%, so it can be confirmed that the SOC error value is effectively corrected by estimating the SOC by considering the current integration.

[0108] FIG. 6 is a table showing an example of an SOC-voltage table according to one embodiment of the present disclosure.

[0109] Referring to FIG. 6, it can be seen that a table organizing SOC corresponding to battery voltage is illustrated. Here, the SOC-voltage table can be changed according to the maximum capacity of the battery. For example, the SOC-voltage table illustrated in FIG. 6 can be applied to a battery having a maximum capacity of 112 Ah. Accordingly, when the maximum capacity of the battery changes, the SOC-voltage table can also be changed accordingly. According to one embodiment, the SOC-voltage table according to the maximum capacity of the battery can be stored in memory, and the processor can receive the SOC-voltage table stored in the memory to perform the SOC estimation method.

[0110] In one embodiment, the processor may calculate a second remaining capacity of the battery from an average voltage for the battery based on the SOC-voltage table. The processor may extract a matching SOC from the average voltage for the battery based on the SOC-voltage table, and multiply the extracted SOC by the total capacity of the battery to calculate the second remaining capacity of the battery. For example, if the average voltage for the battery is 3,959 mV, the SOC may be estimated to be 90% based on the SOC-voltage table, and multiplied by the total capacity of the battery, 114 Ah, to calculate the second remaining capacity as 102,600 mAh. As another example, if the average voltage for the battery is 3,918 mV, the SOC may be estimated to be 85.9% based on the SOC-voltage table, and multiplied by the total capacity of the battery, 114 Ah, to calculate the second remaining capacity as 97,926 mAh.

[0111] FIG. 7 is a flowchart illustrating a method for estimating the SOC of a battery according to some embodiments of the present disclosure. Method (S700) may be performed by at least one processor. Referring to FIG. 7, method (S700) may begin with the processor monitoring current data for multiple batteries connected in series (S710). For example, the processor may monitor the current data of the batteries via a current sensor attached to the batteries. As another example, the processor may receive the current data for the monitored batteries from memory. The processor may receive the current data for the monitored batteries in real time, periodically at predetermined intervals, or aperiodically.

[0112] Next, the processor can monitor multiple voltage data for multiple batteries (S720). Each of the multiple voltage data may correspond to a respective value for each of the multiple batteries. The processor can monitor current data of the batteries via a voltage sensor attached to the batteries. As another example, the processor can receive voltage data for the monitored batteries from memory. The processor can receive voltage data for the monitored batteries in real time, periodically at predetermined intervals, or aperiodically.

[0113] Next, the processor can calculate an average voltage for multiple batteries using the multiple voltage data (S730). For example, the processor can calculate an average voltage for the batteries based on the voltage data of the monitored batteries.

[0114] Next, the processor can calculate the first SOC of the multiple batteries (S740). For example, the processor can calculate the first SOC of the batteries based on monitoring data of the batteries. The processor can calculate the first SOC of the batteries based on a voltage measurement method, a current integration method, or the like, or can calculate the first SOC of the batteries using an extended Kalman filter algorithm.

[0115] Next, the processor can estimate a second SOC, which is a value corrected from the first SOC, based on the current data, average voltage, and the first SOC (S750). The processor can estimate the second SOC of the battery by utilizing multiple mathematical formulas, an SOC-voltage table, etc. stored in the memory.

[0116] Next, the processor may transmit a control signal for managing the battery based on the estimated second SOC (S760). Specifically, if the processor determines that the estimated second SOC of the battery is less than a predetermined threshold, the processor may transmit a control signal to the charger for commanding charging of the battery. For example, if the predetermined threshold is 50%, the processor may transmit a control signal to the charger for commanding charging of the battery if the estimated second SOC of the battery is less than 50%.

[0117] FIG. 8 is a flowchart illustrating a method for estimating a second SOC based on current data, an average voltage, and a first SOC according to some embodiments of the present disclosure. The method (S750) may be performed by at least one processor. Referring to FIG. 8 , the method (S800) may begin with the processor calculating a first remaining capacity based on the first SOC (S810). Here, the first remaining capacity for the battery may be calculated using the following mathematical equation.

[0118] [Mathematical formula]

[0119]

[0120] Next, the processor may calculate a second remaining capacity for the battery based on the average voltage for the battery (S820). Here, the processor may calculate the second remaining capacity from the average voltage based on the SOC-voltage table.

[0121] Next, the processor can calculate a third remaining capacity of the battery based on the current data for the battery, the first remaining capacity of the battery, and the second remaining capacity of the battery (S830). The method for calculating the third remaining capacity is described below with reference to FIG. 9.

[0122] Next, the processor may calculate a second SOC of the battery based on the third remaining capacity of the battery (S840). Here, the processor may calculate the second SOC of the battery by dividing the third remaining capacity of the battery by the maximum capacity of the battery.

[0123] FIG. 9 is a flowchart illustrating a method for calculating a third residual capacity based on current monitoring data according to some embodiments of the present disclosure. The method (S900) may be performed by at least one processor. Referring to FIG. 9 , the method (S900) may begin by monitoring current data for a plurality of batteries connected in series (S910).

[0124] Next, the processor can determine whether the current data of the battery is monitored by the data measurement unit (S920).

[0125] In response to determining that the current data of the battery is monitored (Yes), the processor may calculate the third remaining capacity of the battery by adding the current integration value to the first remaining capacity of the battery (S950). Here, the current integration value may be calculated by multiplying the current data of the battery measured by the data measurement unit by the measurement time. For example, if the current data of the battery measured for 1 second is 40A, the current integration value is 11mAh. can be calculated as

[0126] In response to determining that the battery's current data is not being monitored (No), the processor can determine the battery's stability status (S930). Here, the processor calculates a cumulative average voltage, which is the average value of the battery's average voltage over a certain period of time, and determines that the battery is stabilized if the difference between the average voltage and the cumulative average voltage is less than a certain value, thereby determining the battery's stability status.

[0127] Next, in response to determining that the battery has stabilized, the processor may calculate the third remaining capacity of the battery using the following mathematical formula (S940).

[0128] [Mathematical formula]

[0129]

[0130] Here, a certain value can be calculated by the mathematical formula below, and in the mathematical formula below, the value of a may be less than the capacity of the battery, and the value of b may be less than the value of a.

[0131] [Mathematical formula]

[0132]

[0133] In one embodiment, the predetermined value may represent a slope value for correcting the SOC of the battery. For example, the predetermined value may be decreased to perform the SOC correction of the battery at a fast speed. As another example, the predetermined value may be increased to perform the SOC correction of the battery at a slow speed. Accordingly, the slope value for correcting the SOC of the battery may be determined by adjusting the value of b. For example, when the value of b is increased, the slope value for correcting the SOC of the battery may be decreased, thereby performing the SOC correction of the battery at a fast speed, and when the value of b is decreased, the slope value for correcting the SOC of the battery may be increased, thereby performing the SOC correction of the battery at a slow speed.

[0134] In one embodiment, the predetermined value may have a value of 5,000 to 20,000 depending on the difference between the first remaining capacity and the second remaining capacity. By dividing the predetermined value by the difference between the first remaining capacity and the second remaining capacity in the mathematical formula for calculating the third remaining capacity of the battery, the estimated value of the second SOC for the battery can be prevented from changing rapidly.

[0135] The flowcharts of FIGS. 7 to 9 and the descriptions above are merely examples of the present disclosure, and the scope of the present disclosure is not limited to the flowcharts of FIGS. 7 to 9 and the descriptions above. For example, one or more steps in the flowcharts and the descriptions above may be added / changed / deleted, the order of one or more steps may be changed, and one or more steps may be performed simultaneously.

[0136] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. A method for estimating a State of Charge (SOC) performed by at least one processor, A step of monitoring current data for multiple batteries connected in series; A step of monitoring a plurality of voltage data for the plurality of batteries, each of the plurality of voltage data corresponding to a respective one of the plurality of batteries; A step of calculating an average voltage for the plurality of batteries using the plurality of voltage data; A step of calculating a first SOC of the plurality of batteries; and A step of estimating a second SOC, which is a value corrected from the first SOC, based on the current data, the average voltage, and the first SOC. A method for estimating SOC, including:

2. In paragraph 1, The step of estimating the above second SOC is: A step of calculating a first remaining capacity for the plurality of batteries based on the first SOC; A step of calculating a second residual capacity for the plurality of batteries based on the average voltage; A step of calculating a third residual capacity for the plurality of batteries based on the current data, the first residual capacity, and the second residual capacity; and A step of calculating the second SOC based on the third residual capacity. A method for estimating SOC, including:

3. In paragraph 2, A method for estimating SOC, wherein the first residual capacity is calculated by mathematical expression 1. [Mathematical Formula 1] 4. In paragraph 2, The step of calculating the second residual capacity is: A step of calculating the second residual capacity from the average voltage based on the SOC-voltage table. A method for estimating SOC, including:

5. In paragraph 2, The step of calculating the third residual capacity is: In response to the current data being monitored, a step of calculating the third residual capacity by adding a current integration value to the first residual capacity. A method for estimating SOC, including:

6. In paragraph 2, The step of calculating the third residual capacity is: In response to the above current data not being monitored, a step of determining the stabilization state of the battery A method for estimating SOC, including:

7. In paragraph 6, The step of determining the stability status of the above battery is: A step of calculating a cumulative average voltage, which is an average value of the above average voltage over a certain period of time; and A step of determining that the battery is stabilized when the difference between the average voltage and the accumulated average voltage is less than a certain value. A method for estimating SOC, including:

8. In paragraph 7, The step of calculating the third residual capacity is: In response to determining that the above battery is stabilized, a step of calculating the third remaining capacity by mathematical expression 2 A method for estimating SOC, which further includes: [Equation 2] 9. In paragraph 8, The above constant value is calculated by mathematical formula 3, [Equation 3] A method for estimating SOC, wherein the value of a in the above mathematical expression 3 is less than the capacity of the battery, and the value of b is less than the value of a.

10. In paragraph 2, A method for estimating SOC, wherein the second SOC is calculated by dividing the third residual capacity by the capacity of the battery.

11. In paragraph 1, A step of transmitting a control signal for managing the battery based on the estimated second SOC. A method for estimating SOC, which further includes:

12. In paragraph 11, The step of transmitting the above control signal is: A step of transmitting a control signal commanding charging of the battery in response to determining that the estimated second SOC is less than a predetermined threshold value. A method for estimating SOC, including:

13. A computer program stored on a computer-readable recording medium for executing the method according to any one of paragraphs 1 to 12 on a computer.

14. Memory; and At least one processor connected to said memory and configured to execute at least one computer-readable program contained in said memory Including, At least one program above, Monitor current data for multiple batteries connected in series, Monitoring a plurality of voltage data for the plurality of batteries, each of the plurality of voltage data corresponding to a respective one of the plurality of batteries; Calculate the average voltage for the above multiple voltage data, Calculate the first SOC of the above plurality of batteries, A battery management system comprising commands for estimating a second SOC, which is a value corrected from the first SOC, based on the current data, the average voltage, and the first SOC.

15. In paragraph 14, At least one program above, Calculating a first remaining capacity for the plurality of batteries based on the first SOC, Calculating a second residual capacity for the plurality of batteries based on the average voltage, Calculating a third residual capacity for the plurality of batteries based on the current data, the first residual capacity, and the second residual capacity, Commands for calculating the second SOC based on the third residual capacity A battery management system further comprising:

16. In paragraph 15, At least one program above, Commands for calculating the second residual capacity from the average voltage based on the SOC-voltage table A battery management system further comprising:

17. In paragraph 15, At least one program above, In response to the current data being monitored, instructions for calculating the third residual capacity by adding a current integration value to the first residual capacity. A battery management system further comprising:

18. In paragraph 15, At least one program above, In response to the above current data not being monitored, a cumulative average voltage is calculated, which is an average value of the average voltage over a certain period of time, Commands for determining that the battery is stabilized when the difference between the average voltage and the accumulated average voltage is less than a certain value. A battery management system further comprising:

19. In paragraph 18, At least one program above, In response to determining that the above battery is stabilized, instructions for calculating the third remaining capacity by mathematical expression 4 A battery management system further comprising: [Equation 4] 20. In paragraph 14, At least one program above, Commands for transmitting a control signal for managing the battery based on the estimated second SOC A battery management system further comprising:

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