SOC determination apparatus and SOC determination method for battery bank

Abstract

An SOC determination method and an SOC determination apparatus for a battery bank are provided. The SOC determination method according to the present invention comprises a step of determining a first SOC to be the same as an average SOC of a plurality of battery groups. The SOC determination method further comprises the following steps, which are executed when the first SOC is different from a reference SOC or falls out of a reference SOC range: determining a second SOC to be the same as a maximum SOC or a minimum SOC of the plurality of battery groups; and determining the SOC of the battery bank by applying a weighted sum operation to the first SOC and the second SOC.

Description

SOC determination device and SOC determination method for battery banks

[0001] The present invention relates to a technique for determining the SOC of a battery bank including a plurality of battery groups.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0047587, filed April 8, 2024, and Korean Patent Application No. 10-2025-0039660, filed March 27, 2025, the entire contents of which are disclosed in the specification and drawings of the aforementioned applications are incorporated herein by reference.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage batteries, robots, and satellites has been in full swing, research into high-performance batteries capable of repeated charging and discharging is actively being conducted.

[0004] Currently commercialized batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are receiving attention for their advantages of being able to charge and discharge freely, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based batteries.

[0005] Recently, securing the highest possible capacity is becoming increasingly important for stable power management, not only in energy storage systems but also in electric vehicles. Accordingly, battery banks comprising multiple battery groups, connected in series, parallel, or a combination of series and parallel, are being primarily utilized. These groups are then selectively connected to one or more of the battery groups, depending on external power requirements.

[0006] Excessively high or low SOCs can accelerate deterioration, cause uneven deterioration across multiple battery groups, increase the risk of explosions, and significantly reduce the overall charge / discharge performance of the battery bank. Therefore, it is necessary to control the battery bank so that the SOC of each battery group remains within an appropriate SOC range while suppressing SOC variations across multiple battery groups.

[0007] There may be a certain degree of difference between the average SOC of multiple battery groups and the SOC of individual battery groups. Conventionally, the aforementioned problem can be prevented to some extent by immediately terminating the charging or discharging of the battery bank if the SOC of at least one battery group among the multiple battery groups falls outside the appropriate SOC range.

[0008] However, if the above average SOC is directly notified to the user as the SOC of the battery bank or utilized for controlling the battery system, even though the average SOC (e.g., 98%) is within the appropriate SOC range, the SOC (e.g., 100%) of at least one battery group may be out of the appropriate SOC range, causing sudden termination of charging or discharging, which may cause unexpected great inconvenience to the user of the battery bank and pose a safety threat to the battery system.

[0009] The present invention has been devised to solve the above-described problems, and an object of the present invention is to provide a device and method for determining the SOC of a battery bank as a value that better matches the charge / discharge operation conditions of the battery bank compared to the SOC factors (e.g., average SOC, maximum SOC, and / or minimum SOC) of a plurality of battery groups included in the battery bank.

[0010] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0011] A method for determining an SOC for a battery bank including a plurality of battery groups according to one aspect of the present invention comprises the step of determining a first SOC equal to an average SOC of the plurality of battery groups. The method further comprises the following steps, which are executed when the first SOC is different from a reference SOC or is out of a reference SOC range: determining a second SOC equal to a maximum SOC or a minimum SOC of the plurality of battery groups, depending on whether the battery bank is being charged or discharged; and applying a weighted sum operation to the first SOC and the second SOC to determine the SOC of the battery bank.

[0012] The step of determining the SOC of the battery bank may include a step of determining a first weight and a second weight based on the second SOC, and a step of individually applying the first weight and the second weight to the first SOC and the second SOC to determine the SOC of the battery bank.

[0013] The step of determining the first weight and the second weight may include the following steps, which are executed when the battery bank is being charged and the first SOC is greater than the reference SOC or an upper limit of the reference SOC range: a step of determining the second weight by applying a predetermined positive correspondence relationship to the second SOC, and a step of determining the first weight as a value whose sum with the second weight is equal to a predetermined set value.

[0014] The step of determining the first weight and the second weight may include the following steps, which are executed when the battery bank is discharging and the first SOC is less than the reference SOC or the lower limit of the reference SOC range: determining the first weight by applying a predetermined positive correspondence relationship to the second SOC; and determining the second weight as a value whose sum with the first weight is equal to a predetermined set value.

[0015] The step of determining the first weight and the second weight may include the following steps, which are executed when the battery bank is being charged and the first SOC is greater than the reference SOC or an upper limit of the reference SOC range: determining the first weight by applying a predetermined negative correspondence relationship to the second SOC, and determining the second weight as a value whose sum with the first weight is equal to a predetermined set value.

[0016] The step of determining the first weight and the second weight may include the following steps, which are executed when the battery bank is discharging and the first SOC is less than the reference SOC or an upper limit of the reference SOC range: a step of determining the second weight by applying a predetermined negative correspondence relationship to the second SOC, and a step of determining the first weight as a value whose sum with the second weight is equal to a predetermined set value.

[0017] The above SOC determination method may further include a step of determining the SOC of the battery bank to be the same as the first SOC when the first SOC is the same as the reference SOC or within the reference SOC range.

[0018] The step of determining the second SOC may determine the second SOC to be equal to the maximum SOC when the battery bank is being charged, and may determine the second SOC to be equal to the minimum SOC when the battery bank is being discharged.

[0019] The above SOC determination method may further include a step of stopping charging and discharging of the battery bank when the SOC of the battery bank reaches an upper or lower limit of an allowable SOC range or is outside the allowable SOC range.

[0020] According to another aspect of the present invention, a method for determining an SOC for a battery bank including a plurality of battery groups includes a step of determining a first SOC equal to an average SOC of the plurality of battery groups. The method further includes the following steps, which are executed when the first SOC is different from a reference SOC or is out of a reference SOC range: determining a second SOC equal to a maximum SOC or a minimum SOC of the plurality of battery groups, depending on whether the battery bank is being charged or discharged; determining a first weight and a second weight based on the second SOC; determining a third SOC by applying a first weighted sum operation to the first SOC and the second SOC; and determining the SOC of the battery bank by applying a second weighted sum operation to the third SOC and a previous SOC of the battery bank.

[0021] The above SOC determination method may further include a step of determining the third SOC to be the same as the first SOC when the first SOC is the same as the reference SOC or is within the reference SOC range.

[0022] The step of determining the SOC of the battery bank includes the step of determining a third weight and a fourth weight based on a difference between the third SOC and the previous SOC of the battery bank, and the step of individually applying the third weight and the fourth weight to the third SOC and the previous SOC of the battery bank to determine the SOC of the battery bank.

[0023] According to another aspect of the present invention, a device for determining an SOC for a battery bank including a plurality of battery groups includes a processor for determining a first SOC equal to an average SOC of the plurality of battery groups. The processor is configured to perform the following operations when the first SOC is different from a reference SOC or is out of a reference SOC range: determining a second SOC equal to a maximum SOC or a minimum SOC of the plurality of battery groups, depending on whether the battery bank is being charged or discharged; and applying a weighted sum operation to the first SOC and the second SOC to determine the SOC of the battery bank.

[0024] According to another aspect of the present invention, a device for determining an SOC for a battery bank including a plurality of battery groups includes a processor for determining a first SOC equal to an average SOC of the plurality of battery groups. The processor is configured to perform the following operations when the first SOC is different from a reference SOC or is out of a reference SOC range: determining a second SOC equal to a maximum SOC or a minimum SOC of the plurality of battery groups, depending on whether the battery bank is being charged or discharged; determining a third SOC by applying a first weighted sum operation to the first SOC and the second SOC; and determining the SOC of the battery bank by applying a second weighted sum operation to the third SOC and a previous SOC of the battery bank.

[0025] A battery system according to another aspect of the present invention includes the SOC determination device.

[0026] According to at least one of the embodiments of the present invention, by applying a mathematical operation corresponding to the charge / discharge operation conditions of the battery bank to the SOC factors (e.g., average SOC, maximum SOC, and / or minimum SOC) of a plurality of battery groups included in the battery bank, the SOC of the battery bank can be determined as a value that better matches the charge / discharge operation conditions of the battery bank compared to the SOC factors.

[0027] The SOC of the battery bank determined according to the present invention can be used in place of the above SOC factors to determine whether charging and discharging of the battery bank is interrupted, thereby preventing a sudden charging and discharging interruption in advance.

[0028] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0029] 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.

[0030] Figure 1 is a drawing exemplarily showing the configuration of a battery system (1) according to the present invention.

[0031] FIG. 2 is a flowchart exemplarily showing a SOC determination method according to the first embodiment of the present invention.

[0032] FIG. 3 is a flowchart schematically illustrating an example of executable subroutines in step S242 of the method of FIG. 2.

[0033] Figure 4 is a drawing referenced in explaining the method of Figure 3.

[0034] FIG. 5 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2.

[0035] Figure 6 is a drawing referenced in explaining the method of Figure 5.

[0036] FIG. 7 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2.

[0037] FIG. 8 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2.

[0038] Fig. 9 is a flowchart exemplarily showing a SOC determination method according to a second embodiment of the present invention.

[0039] Fig. 10 is a flowchart exemplarily showing a SOC determination method according to a third embodiment of the present invention.

[0040] Fig. 11 is a flowchart exemplarily showing a SOC determination method according to a fourth embodiment of the present invention.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that conforms to the technical spirit of the present invention.

[0042] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0043] Terms that include ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

[0044] Throughout the specification, when a part is said to "include" a component, this does not exclude other components, unless otherwise stated, but rather implies that other components may be included. Furthermore, terms such as "unit" used throughout the specification mean a unit that processes at least one function or operation, and may be implemented using hardware, software, or a combination of hardware and software.

[0045] Additionally, throughout the specification, when we say that a part is "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with other elements in between.

[0046] Figure 1 is a drawing exemplarily showing the configuration of a battery system (1) according to the present invention.

[0047] Referring to FIG. 1, the battery system (1) includes a battery bank (BB), a battery monitoring device (120), and a power conversion system (10).

[0048] The power conversion system (10) is electrically connected between the battery bank (BB) and the power system (2) and / or the electric load (3).

[0049] The power conversion system (10) uses a DC-AC inverter and / or a DC-DC converter provided therein to transfer power between the battery bank (BB) and the power system (2) and / or between the battery bank (BB) and the electric load (3). That is, the power conversion system (10), while operating in battery charging mode, can convert AC power supplied from the power system (2) into DC power and supply it to the battery bank (BB).

[0050] In addition, the power conversion system (10) can convert direct current power input by discharging the battery bank (BB) into alternating current power while operating in battery discharge mode and supply it to the power system (2) and / or electric load (3).

[0051] The battery monitoring device (120) can acquire status information of the battery bank (BB) and, based on the acquired status information, transmit a charge command, a discharge command, and / or a standby command to the power conversion system (10). When receiving a charge command, the power conversion system (10) can operate the DC-AC inverter in a battery charge mode. When receiving a discharge command, the power conversion system (10) can operate the DC-AC inverter in a battery discharge mode.

[0052] The charge command is a signal requesting that DC power be supplied to the battery bank (BB). The discharge command is a signal requesting that DC power be extracted from the battery bank (BB). The standby command is a signal requesting that both the charge and discharge operations be stopped.

[0053] A battery bank (BB) includes multiple battery groups (BG_1 to BG_m). m is a natural number greater than or equal to 2. In this specification, when describing common content across multiple battery groups (BG_1 to BG_m), the symbol "BG" is assigned to each battery group. A battery group (BG) may also be referred to as a "battery pack" or a "battery rack" depending on the application to which it is applied.

[0054] For convenience of explanation, Fig. 1 shows m=6, i.e., the battery bank (BB) includes a total of six battery groups (BG_1 to BG_6), but the number of battery groups (BG) is not particularly limited as long as it is two or more.

[0055] A battery group (BG) includes one battery cell (BC) or two or more battery cells (BC) connected in series. In this specification, a battery cell (BC) refers to a basic unit of a battery capable of independent charging and discharging, and is not particularly limited as long as it is rechargeable, such as a lithium-ion cell.

[0056] If the SOC determination methods to be described later are executed by the battery monitoring device (120), the battery monitoring device (120) may be referred to as a 'SOC determination device'.

[0057] The battery monitoring device (120) may be configured to control charging and discharging of a plurality of battery groups (BG_1 to BG_m) to suppress SOC deviation and / or SOH deviation between the plurality of battery groups (BG_1 to BG_m).

[0058] The battery monitoring device (120) includes a processor (400). The battery monitoring device (120) may further include at least one of a plurality of switches (200_1 to 200_m) and a plurality of sensing circuits (300_1 to 300_m).

[0059] A plurality of switches (200_1 to 200_m) are individually connected in series to a plurality of battery groups (BG_1 to BG_m) one-to-one. That is, any two or more of the plurality of battery groups (BG_1 to BG_m) can be connected in parallel to each other through the plurality of switches (200_1 to 200_m).

[0060] In this specification, when describing common contents of multiple switches (200_1 to 200_m), the symbol '200' is assigned to the switch. The switch (200) is not particularly limited as long as it can turn on and off the current path between the battery group (BG) and the power conversion system (10). For example, a semiconductor switch such as a MOSFET or a mechanical switch such as a relay can be used as the switch (20). As another example, a bidirectional DC-DC converter can be used as the switch (200).

[0061] Assuming that i is a natural number less than or equal to m, charging and discharging of the battery group (BG_i) is possible while the switch (200_i) is turned on. While the switch (200_i) is turned off, the battery group (BG_i) is electrically isolated from other battery groups of the battery bank (BB) and also electrically isolated from the power conversion system (10).

[0062] A plurality of sensing circuits (300_1 to 300_m) are individually provided to a plurality of battery groups (BG_1 to BG_m). In this specification, when describing common contents of a plurality of sensing circuits (300_1 to 300_m), the sensing circuits are given the symbol '300'.

[0063] The sensing circuit (300) includes a voltage sensor (310) and a current sensor (320). The sensing circuit (300) uses the voltage sensor (310) and the current sensor (320) to measure the voltage and current of the battery group (BG) to which it is connected. The voltage sensor (310) is connected in parallel to the battery group (BG) and measures the voltage between the two terminals of the battery group (BG). The current sensor (320) is installed in a power line connecting the battery group (BG) and the switch (200) and measures the current flowing through the battery group (BG). The sensing circuit (300) generates a sensing signal representing the measured voltage and the measured current. The sensing signal may refer to a pair of synchronously detected voltage values ​​and current values.

[0064] The processor (400) is individually operably coupled to a plurality of switches (200_1 to 200_m), a plurality of sensing circuits (300_1 to 300_m), and a power conversion system (10). The operably coupled nature of the two components means that the two components are connected so as to be capable of transmitting and receiving signals in one or both directions.

[0065] The processor (400) may be implemented in hardware using at least one of ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), microprocessors, and other electrical units for performing functions.

[0066] The processor (400) may have a memory device. The memory device may include at least one type of storage medium among a flash memory type, a hard disk type, an SSD (Solid State Disk type), an SDD (Silicon Disk Drive type), a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), and a programmable read-only memory (PROM). The memory device may store data and a program required for an operation by the processor (400). The memory device may store data indicating a result of an operation by the processor (400).

[0067] The processor (400) can periodically collect sensing signals from each of the plurality of sensing circuits (300_1 to 300_m). Based on the sensing signals, the processor (400) can determine the state of charge (SOC) of each of the plurality of battery groups (BG_1 to BG_m) and additionally determine the state of health (SOH).

[0068] State of Charge (SOC) is the ratio of remaining capacity to maximum capacity, typically expressed in a range of 0 to 100%. Remaining capacity represents the amount of charge currently stored in a battery group (BG).

[0069] SOH is the ratio of the maximum capacity to the design capacity, and is usually expressed in the range of 0 to 100%. The design capacity represents the maximum amount of charge that can be stored in a battery group (BG) when the battery group (BG) is in a new state. The maximum capacity represents the maximum amount of charge that can be stored in a battery group (BG) when the battery group (BG) is deteriorated from a new state. As the battery group (BG) deteriorates, the maximum capacity gradually decreases from the design capacity. Since SOC and SOH can each be estimated from one or a combination of two or more of various known techniques, a detailed description thereof will be omitted.

[0070] Hereinafter, various embodiments for determining the SOC of a battery bank (BB) according to the charge / discharge operation conditions of the battery bank (BB) will be described with reference to FIGS. 2 to 11. The charge / discharge operation conditions may be terms referring to the operating state of the battery bank (BB), such as whether the battery bank (BB) is charging, whether the battery bank (BB) is discharging, the SOC of at least one of a plurality of battery groups (BG_1 to BG_m), etc.

[0071] FIG. 2 is a flowchart exemplarily showing a method for determining SOC according to a first embodiment of the present invention. The method of FIG. 2 can be executed by the battery monitoring device (120) illustrated in FIG. 1. The battery monitoring device (120) can periodically determine the SOC of each battery group during charging or discharging of the battery bank (BB).

[0072] Referring to FIGS. 1 and 2, in step S210, the processor (400) determines a first SOC equal to the average SOC of the plurality of battery groups (BG_1 to BG_m). For example, the first SOC may represent an arithmetic mean or a harmonic mean of the SOC values ​​of the plurality of battery groups (BG_1 to BG_m).

[0073] In step S220, the processor (400) determines whether the first SOC is equal to the reference SOC. The reference SOC may be predetermined, such as a median value (e.g., 50%) of a predetermined allowable SOC range (e.g., 0 to 100%, or 2 to 98%) of a battery group (BG). A value of "No" in step S220 indicates that the first SOC is different from the reference SOC. If the value of step S220 is "No," step S230 is performed. If the value of step S220 is "Yes," step S250 is performed.

[0074] In step S230, the processor (400) determines the second SOC as being equal to the maximum SOC or minimum SOC of the plurality of battery groups (BG_1 to BG_m) depending on whether the battery bank (BB) is charging or discharging. For example, if the battery bank (BB) is charging, the maximum SOC of the plurality of battery groups (BG_1 to BG_m) may be determined as the second SOC. As another example, if the battery bank (BB) is discharging, the minimum SOC of the plurality of battery groups (BG_1 to BG_m) may be determined as the second SOC.

[0075] In step S240, the processor (400) determines the SOC of the battery bank (BB) by applying a weighted sum operation (see Relationships 1 to 4 described below) to the first SOC and the second SOC. Step S240 may include steps S242 and S244.

[0076] In step S242, the processor (400) determines a first weight and a second weight based on the second SOC. The first weight may be for the first SOC, and the second weight may be for the second SOC. Step S242 will be described separately later with reference to FIGS. 4 and 8.

[0077] In step S244, the processor (400) determines the SOC of the battery bank (BB) by individually applying the first weight and the second weight to the first SOC and the second SOC. That is, the SOC of the battery bank (BB) may represent a weighted sum of the first SOC and the second SOC using the first weight and the second weight.

[0078] In step S250, the processor (400) determines the SOC of the battery bank (BB) in the same manner as the first SOC. The SOC of the battery bank (BB) may be referred to as, for example, a 'bank SOC', a 'representative SOC', or a 'system SOC'.

[0079] FIG. 3 is a flowchart schematically illustrating an example of executable subroutines in step S242 of the method of FIG. 2, and FIG. 4 is a drawing referenced in explaining the method of FIG. 3.

[0080] Referring to FIG. 3, in step S310, the processor (400) determines whether the battery bank (BB) is charging and whether the first SOC is greater than the reference SOC. If the battery bank (BB) is discharging or at rest, or the first SOC is less than the reference SOC, the value of step S310 is “No.” If the value of step S310 is “Yes,” step S320 is performed. FIG. 4 illustrates a situation where m = 5 and the first SOC = 62%. If the reference SOC = 50%, the value of step S310 is output as “Yes.”

[0081] In step S320, the processor (400) applies a predetermined first positive correspondence relationship to a second SOC (e.g., maximum SOC) to determine a second weight.

[0082] The following relational expression 1 may be an example of the first positive correspondence relation.

[0083] <Relationship 1>

[0084]

[0085] In relation 1, x is the second SOC, U A is a predetermined positive integer, A k is a predetermined k-th coefficient corresponding to the index k, A0 is a predefined positive number (e.g., 0.5) greater than or equal to the reference value corresponding to the reference SOC, y A (x) represents the second weight. y A The maximum value of (x) can be limited to a predetermined set value (e.g., 1).

[0086] The first positive correspondence relationship is not limited to relation 1. If the second SOC is between the reference SOC and the upper limit of the allowable SOC range, and if the second weight increases as the second SOC increases, other mathematical operations other than relation 1 may be used as the first positive correspondence relationship.

[0087] In step S330, the processor (400) determines the first weight as a value whose sum with the second weight determined in step S320 is equal to the set value. That is, the second weight = set value - the first weight.

[0088] FIG. 5 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2, and FIG. 6 is a drawing referenced in explaining the method of FIG. 5.

[0089] Referring to FIG. 5, in step S510, the processor (400) determines whether the battery bank (BB) is discharging and whether the first SOC is less than the reference SOC. If the battery bank (BB) is charging or resting, or the first SOC is greater than the reference SOC, the value of step S510 is “No.” If the value of step S510 is “Yes,” step S520 is performed. FIG. 6 illustrates a situation where m = 5 and the first SOC = 39%. If the reference SOC = 50%, the value of step S510 is output as “Yes.”

[0090] In step S520, the processor (400) applies a predetermined second positive correspondence relationship to a second SOC (e.g., minimum SOC) to determine a first weight.

[0091] The following relational expression 2 may be an example of a second positive correspondence relation.

[0092] <Relationship 2>

[0093]

[0094] In relation 2, x is the second SOC, U B is a predetermined positive integer, B k is a predetermined k-th coefficient corresponding to the index k, B0 is a predetermined constant less than the reference value, y B (x) represents the first weight. y B The maximum value of (x) may be limited to a reference value. B0 may be equal to a ratio value (e.g., 0, 0.02) corresponding to the lower limit of the allowable SOC range (e.g., 0%, 2%).

[0095] The second positive correspondence relationship is not limited to relation 2. If the second SOC is between the lower limit of the allowable SOC range and the reference value, and if the decrease in the second SOC induces a decrease in the first weight, other mathematical operations other than relation 2 may be used as the second positive correspondence relationship.

[0096] In step S530, the processor (400) determines the second weight as a value whose sum with the first weight determined in step S520 becomes equal to a predetermined set value. That is, the second weight = set value - the first weight. Since the second positive correspondence relationship induces a decrease in the first weight according to a decrease in the second SOC, the second weight determined in step S530 may increase as the second SOC decreases.

[0097] FIG. 7 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2. In explaining the method of FIG. 7, FIG. 4 may be referred to again to aid understanding.

[0098] Referring to FIG. 7, in step S710, the processor (400) determines whether the battery bank (BB) is being charged and whether the first SOC is greater than the reference SOC. If the value of step S710 is “Yes,” step S720 is performed.

[0099] In step S720, the processor (400) applies a predetermined first negative correspondence relationship to a second SOC (e.g., maximum SOC) to determine a first weight.

[0100] The following relational expression 3 may be an example of the first negative correspondence relation.

[0101] <Relationship 3>

[0102]

[0103] In relation 3, x is the second SOC, U C is a predefined positive integer, C k is a predetermined k-th coefficient corresponding to the index k, C0 is a predetermined constant (e.g., equal to the reference value), y C (x) represents the first weight. y C The maximum value of (x) can be limited to a reference value.

[0104] The first negative correspondence relationship is not limited to relation 3. If the second SOC is between the lower limit of the allowable SOC range and the reference value, and if it induces a decrease in the first weight as the second SOC increases, other mathematical operations other than relation 3 may be used as the first negative correspondence relationship.

[0105] In step S730, the processor (400) determines the second weight as a value whose sum with the first weight determined in step S720 becomes equal to a predetermined set value. Since the first negative correspondence induces a decrease in the first weight as the second SOC increases, the second weight determined in step S730 may increase as the second SOC increases.

[0106] FIG. 8 is a flowchart schematically illustrating another example of executable subroutines in step S242 of the method of FIG. 2. In describing the method of FIG. 8, FIG. 6 may be referred to again.

[0107] Referring to FIG. 8, in step S810, the processor (400) determines whether the battery bank (BB) is discharging and whether the first SOC is less than the reference SOC. If the value of step S810 is “Yes,” step S820 is performed.

[0108] In step S820, the processor (400) applies a predetermined second negative correspondence relationship to a second SOC (e.g., minimum SOC) to determine a second weight.

[0109] The following relational expression 4 may be an example of the second negative correspondence relationship.

[0110] <Relationship 4>

[0111]

[0112] In relation 4, x is the second SOC, U D is a predetermined positive integer, D k is a predetermined k-th coefficient corresponding to the index k, D0 is a predetermined constant (e.g., equal to the set value), y D (x) represents the second weight. y D The maximum value of (x) can be limited to a set value.

[0113] The second negative correspondence relationship is not limited to relation 4. If the second SOC is between the reference value and the lower limit of the allowable SOC range, and if the decrease in the second SOC induces an increase in the second weight, other mathematical operations other than relation 4 may be used as the second negative correspondence relationship.

[0114] In step S830, the processor (400) determines the first weight as a value whose sum with the second weight determined in step S820 becomes equal to a predetermined set value. Since the second negative correspondence induces an increase in the second weight as the second SOC decreases, the first weight determined in step S830 may become smaller as the second SOC decreases.

[0115] If the value of step S310 of FIG. 3, the value of step S510 of FIG. 6, the value of step S710 of FIG. 7, or the value of step S810 of FIG. 8 is “No”, step S250 of FIG. 2 may be executed.

[0116] When the first weight and the second weight are determined through the method of FIG. 3, FIG. 5, FIG. 7 or FIG. 8, the SOC of the battery bank (BB) determined in step S244 of FIG. 2 can satisfy the following relational expression 5.

[0117] <Relationship 5>

[0118]

[0119] In equation 5, SOC Bank SOC, SOC of battery bank (BB) 1_G is the 1st SOC, SOC 2_G is the second SOC, w1 is the first weight, and w2 is the second weight.

[0120] As described above, in a situation where the battery bank (BB) is being charged, the SOC of the battery bank (BB) can be determined to be equal to the upper limit of the allowable SOC range at or before the second SOC reaches the upper limit of the allowable SOC range. Accordingly, a situation in which the SOC of at least one battery group reaches the upper limit of the allowable SOC range before the average SOC reaches the upper limit of the allowable SOC range can be prevented, and as a result, a problem in which the charging of the battery bank (BB) is suddenly terminated can be automatically resolved.

[0121] In a situation where the battery bank (BB) is being discharged, the SOC of the battery bank (BB) can be determined to be equal to the lower limit of the allowable SOC range at or before the second SOC reaches the lower limit of the allowable SOC range. Accordingly, a situation in which the SOC of at least one battery group reaches the lower limit of the allowable SOC range before the average SOC reaches the lower limit of the allowable SOC range can be prevented, and as a result, the problem of the discharge of the battery bank (BB) suddenly ending can also be automatically resolved.

[0122] For reference, w1 and w2 may be obtained as a result of executing any one of FIG. 3, FIG. 5, FIG. 7, and FIG. 8. That is, a combination of the first weight obtained by any one of the four methods according to FIG. 3, FIG. 5, FIG. 7, and FIG. 8 and the second weight obtained by any one of the remaining three methods may not be used as w1 and w2 in relational expression 5.

[0123] Fig. 9 is a flowchart exemplifying a method for determining SOC according to a second embodiment of the present invention. The method of Fig. 9 can be executed by the battery monitoring device (120) illustrated in Fig. 1. The battery monitoring device (120) can periodically determine the SOC of each battery group during charging of the battery bank (BB).

[0124] Referring to FIGS. 1 and 9, in step S910, the processor (400) determines a first SOC equal to the average SOC of a plurality of battery groups (BG_1 to BG_m).

[0125] In step S920, the processor (400) determines whether the first SOC is within a reference SOC range. The reference SOC range may be preset to be narrower than a predetermined allowable SOC range for the battery group (BG). The upper limit of the reference SOC range may be referred to as the first reference SOC (e.g., 60%), and the lower limit of the reference SOC range may be referred to as the second reference SOC (e.g., 40%). That is, if the first SOC is less than or equal to the first reference SOC and greater than or equal to the second reference SOC, the value of step S920 is “yes.” If the value of step S920 is “no,” step S930 is performed. If the value of step S920 is “yes,” step S950 is performed.

[0126] In step S930, the processor (400) determines a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups (BG_1 to BG_m), depending on whether the battery bank (BB) is charging or discharging.

[0127] In step S940, the processor (400) determines the SOC of the battery bank (BB) by applying a weighted sum operation to the first SOC and the second SOC. Step S940 may include steps S942 and S944.

[0128] In step S942, the processor (400) determines a first weight and a second weight. The first weight may be for the first SOC, and the second weight may be for the first SOC.

[0129] In step S944, the processor (400) determines the SOC of the battery bank (BB) by individually applying the first weight and the second weight to the first SOC and the second SOC.

[0130] In step S950, the processor (400) determines the SOC of the battery bank (BB) in the same manner as the first SOC.

[0131] Meanwhile, the content of the first embodiment described above with reference to FIGS. 3 to 8 may also be common to step S942 according to the second embodiment described above with reference to FIG. 9, provided that the following modifications are applied.

[0132] A modification required to apply the method of FIGS. 3 and 7 to step S942 of FIG. 9 may be that the 'reference SOC' and 'reference value' described with reference to FIGS. 3 and 7 may be replaced with 'first reference SOC' and 'first reference value', respectively. Here, the first reference value may be a ratio value of 0 to 1 corresponding to the first reference SOC. For example, if the first reference SOC is 60%, the first reference value may be 0.6.

[0133] A modification required to apply the method of FIGS. 5 and 8 to step S942 of FIG. 9 may be that the 'reference SOC' and 'reference value' described with reference to FIGS. 5 and 8 may be replaced with 'second reference SOC' and 'second reference value', respectively. Here, the second reference value may be a ratio value of 0 to 1 corresponding to the second reference SO'. For example, if the second reference SOC is 40%, the first reference value may be 0.4.

[0134] Fig. 10 is a flowchart exemplifying a method for determining SOC according to a third embodiment of the present invention. The method of Fig. 10 can be executed by the battery monitoring device (120) illustrated in Fig. 1. The battery monitoring device (120) can periodically determine the SOC of each battery group during charging or discharging of the battery bank (BB).

[0135] Referring to FIGS. 1 and 10, in step S1010, the processor (400) determines a first SOC equal to the average SOC of a plurality of battery groups (BG_1 to BG_m).

[0136] In step S1020, the processor (400) determines whether the first SOC is equal to the reference SOC. If the value of step S1020 is "No," step S1030 is performed. If the value of step S1020 is "Yes," step S1050 is performed.

[0137] In step S1030, the processor (400) determines a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups (BG_1 to BG_m), depending on whether the battery bank (BB) is charging or discharging.

[0138] In step S1040, the processor (400) applies a first weighted sum operation to the first SOC and the second SOC to determine a third SOC. Step S1040 may include steps S1042 and S1044.

[0139] In step S1042, the processor (400) determines the first weight and the second weight based on the second SOC.

[0140] Steps S1010, S1020, S1030, and S1042 of FIG. 10 may be substantially identical to steps S210, S220, S230, and S242 of FIG. 2, respectively.

[0141] In step S1044, the processor (400) determines a third SOC by individually applying a first weight and a second weight to the first SOC and the second SOC. The third SOC may be the same as the SOC of the battery bank (BB) determined by step S244. That is, the above-described relational expression 5 may be utilized as the first weighted sum operation in step S1040, and in this case, the SOC of relational expression 5 Bank represents the third SOC, which is a temporary SOC before the SOC of the battery bank (BB) is confirmed.

[0142] In step S1050, the processor (400) determines the third SOC in the same manner as the first SOC.

[0143] In step S1060, the processor (400) determines the SOC of the battery bank (BB) by applying a second weighted sum operation to the third SOC and the previous SOC of the battery bank (BB). Since the SOC of the battery bank (BB) is periodically updated, the SOC of the battery bank (BB) previously determined by the method according to FIG. 10 can be used as the previous SOC in step S1062.

[0144] Step S1060 may include steps S1062 and S1064.

[0145] In step S1062, the processor (400) determines a third weight and a fourth weight based on the difference between the third SOC and the previous SOC of the battery bank (BB). The sum of the third weight and the fourth weight may be equal to the set value.

[0146] The processor (400) may determine a third weight by applying a predetermined third positive correspondence relationship to the difference (which may be an absolute value) between the third SOC and the previous SOC of the battery bank (BB) when (i) the battery bank (BB) is charging and the third SOC is greater than the previous SOC of the battery bank (BB) or (ii) the battery bank (BB) is discharging and the third SOC is less than the previous SOC of the battery bank (BB). At this time, the fourth weight may be determined to be equal to a value obtained by subtracting the third weight determined using the third positive correspondence relationship from the set value. The following relational expression 6 may be an example of the third positive correspondence relationship.

[0147] <Relationship 6>

[0148]

[0149] In equation 6, SOC 3_G is the 3rd SOC, SOC Bank_prv is the previous SOC of the battery bank (BB), x is the difference between the third SOC and the previous SOC, U Eis a predetermined positive integer, E k represents a predetermined kth coefficient corresponding to index k. y E (x) represents the third weight. E0 can be a predefined positive number less than the set value (e.g., 1 / 2 of the set value). y E The minimum value of (x) can be limited to E0. y E The maximum value of (x) can be limited to a first threshold value. The first threshold value can be a value set in advance below the above setting value. That is, y calculated using the third positive correspondence relationship E When (x) exceeds the first threshold, the third weight can be determined to be the same as the first threshold.

[0150] Alternatively, the processor (400) may determine the fourth weight by applying a predetermined third negative correspondence to the difference (which may be an absolute value) between the third SOC and the previous SOC of the battery bank (BB) when (i) the battery bank (BB) is charging and the third SOC is greater than the previous SOC of the battery bank (BB) or (ii) the battery bank (BB) is discharging and the third SOC is less than the previous SOC of the battery bank (BB). In this case, the third weight may be determined to be equal to a value obtained by subtracting the fourth weight determined using the third negative correspondence from the set value. The following relational expression 7 may be an example of the third negative correspondence.

[0151] <Relationship 7>

[0152]

[0153] In relation 7, U F is a predetermined positive integer, F k is a predetermined kth coefficient corresponding to index k, y F (x) represents the fourth weight, and F0 represents a predefined positive number smaller than the set value (e.g., 1 / 2 of the set value). x can be the same as in equation 6. y FThe minimum value of (x) can be limited to a second threshold. The second threshold can be a predetermined positive number less than F0. That is, y calculated using the third positive correspondence F If (x) is below the second threshold, the fourth weight can be determined to be the same as the second threshold.

[0154] In step S1064, the processor (400) determines the SOC of the battery bank (BB) by individually applying the third weight and the fourth weight to the third SOC and the previous SOC of the battery bank (BB).

[0155] The following relational expression 8 is an example of a second weighted sum operation that can be used in step S1060.

[0156] <Relationship 8>

[0157]

[0158] In equation 8, SOC Bank SOC, SOC of battery bank (BB) 3_G is the 3rd SOC, SOC Bank_prv represents the previous SOC of the battery bank (BB). w3 is the third weight, and w4 is the fourth weight.

[0159] Fig. 11 is a flowchart exemplifying a method for determining SOC according to a fourth embodiment of the present invention. The method of Fig. 11 can be executed by the battery monitoring device (120) illustrated in Fig. 1. The battery monitoring device (120) can periodically determine the SOC of each battery group during charging or discharging of the battery bank (BB).

[0160] Referring to FIGS. 1 and 11, in step S1110, the processor (400) determines a first SOC equal to the average SOC of a plurality of battery groups (BG_1 to BG_m).

[0161] In step S1120, the processor (400) determines whether the first SOC is within the reference SOC range. That is, if the first SOC is less than or equal to the first reference SOC and greater than or equal to the second reference SOC, the value of step S1120 is "yes." If the value of step S1120 is "no," step S1130 is performed. If the value of step S1120 is "yes," step S1150 is performed.

[0162] In step S1130, the processor (400) determines a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups (BG_1 to BG_m), depending on whether the battery bank (BB) is charging or discharging.

[0163] In step S1140, the processor (400) applies a first weighted sum operation (see relations 1 to 4 described above) to the first SOC and the second SOC to determine the third SOC. Step S1140 may include steps S1142 and S1144.

[0164] In step S1142, the processor (400) determines the first weight and the second weight based on the second SOC.

[0165] Steps S1110, S1120, S1130, and S1142 of FIG. 11 may be substantially identical to steps S910, S920, S930, and S942 of FIG. 9, respectively.

[0166] In step S1144, the processor (400) determines a third SOC by individually applying a first weight and a second weight to the first SOC and the second SOC. The third SOC may be the same as the SOC of the battery bank (BB) determined in step S944.

[0167] In step S1150, the processor (400) determines the third SOC in the same manner as the first SOC.

[0168] In step S1160, the processor (400) determines the SOC of the battery bank (BB) by applying a second weighted sum operation to the third SOC and the previous SOC of the battery bank (BB). Step S1160 may include steps S1162 and S1164.

[0169] In step S1162, the processor (400) determines a third weight and a fourth weight based on the difference between the third SOC and the previous SOC of the battery bank (BB). The sum of the third weight and the fourth weight may be equal to the set value.

[0170] In step S1164, the processor (400) determines the SOC of the battery bank (BB) by individually applying the third weight and the fourth weight to the third SOC and the previous SOC of the battery bank (BB).

[0171] Steps S1162 and S1164 of FIG. 11 may be individually identical to steps S1062 and S1064 of FIG. 10.

[0172] The processor (400) can determine whether to stop charging and discharging of the battery bank (BB) based on the SOC of the battery bank (BB) determined in step S240, step S940, step S1060, or step S1160.

[0173] In detail, when the SOC of the battery bank (BB) reaches the upper or lower limit of the allowable SOC range or goes outside the allowable SOC range, the processor (400) can stop charging and discharging of the battery bank (BB). Accordingly, the battery groups (BG_1 to BG_m) of the battery bank (BB) can be protected from overcharge and overdischarge.

[0174] For example, when the SOC of the battery bank (BB) reaches the upper limit of the allowable SOC range during charging of the battery bank (BB), the processor (400) may transmit a standby command to the power conversion system (10) or turn off a plurality of switches (200_1 to 200_m).

[0175] As another example, when the SOC of the battery bank (BB) reaches the lower limit of the allowable SOC range during the discharge of the battery bank (BB), the processor (400) may transmit a standby command to the power conversion system (10) or turn off a plurality of switches (200_1 to 200_m).

[0176] The embodiments of the present invention described above are not implemented only through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

[0177] 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.

[0178] In addition, the present invention described above is not limited to the above-described embodiments and the attached drawings, and all or part of each embodiment may be selectively combined and configured so that various modifications can be made, as those skilled in the art can make various substitutions, modifications, and changes within the scope of the technical idea of ​​the present invention.

Claims

1. A method for determining SOC for a battery bank including multiple battery groups, A step of determining a first SOC equal to the average SOC of the plurality of battery groups is included, The following steps are executed when the first SOC is different from the reference SOC or is outside the reference SOC range: a step of determining a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups, depending on whether the battery bank is charging or discharging; and A step of determining the SOC of the battery bank by applying a weighted sum operation to the first SOC and the second SOC; A method for determining SOC, which further includes:

2. In paragraph 1, The step of determining the SOC of the above battery bank is: A step of determining a first weight and a second weight based on the second SOC; and A step of determining the SOC of the battery bank by individually applying the first weight and the second weight to the first SOC and the second SOC; A method for determining SOC, including:

3. In paragraph 2, The step of determining the first and second weights is: The following steps are executed when the above battery bank is charging and the first SOC is greater than the reference SOC or the upper limit of the reference SOC range: A step of applying a predetermined positive correspondence relationship to the second SOC to determine the second weight; and A step of determining the first weight as a value whose sum with the second weight is equal to a predetermined set value; A method for determining SOC, including:

4. In paragraph 2, The step of determining the first and second weights is: The following steps are executed when the above battery bank is discharging and the first SOC is less than the reference SOC or the lower limit of the reference SOC range: A step of applying a predetermined positive correspondence relationship to the second SOC to determine the first weight; and A step of determining the second weight as a value whose sum with the first weight is equal to a predetermined set value; A method for determining SOC, including:

5. In paragraph 2, The step of determining the first and second weights is: The following steps are executed when the above battery bank is charging and the first SOC is greater than the reference SOC or the upper limit of the reference SOC range: A step of determining the first weight by applying a predetermined negative correspondence relationship to the second SOC; and A step of determining the second weight as a value whose sum with the first weight is equal to a predetermined set value; A method for determining SOC, including:

6. In paragraph 2, The step of determining the first and second weights is: The following steps are executed when the above battery bank is discharging and the first SOC is less than the reference SOC or the upper limit of the reference SOC range: A step of applying a predetermined negative correspondence relationship to the second SOC to determine the second weight; and A step of determining the first weight as a value whose sum with the second weight is equal to a predetermined set value; A method for determining SOC, including:

7. In paragraph 2, A step of determining the SOC of the battery bank to be the same as the first SOC when the first SOC is equal to the reference SOC or within the reference SOC range; A method for determining SOC, which further includes:

8. In paragraph 1, The step of determining the above second SOC is: If the above battery bank is charging, the second SOC is determined to be equal to the above maximum SOC, A method for determining an SOC, wherein the second SOC is determined to be equal to the minimum SOC when the battery bank is being discharged.

9. In paragraph 1, A step of stopping charging and discharging of the battery bank when the SOC of the battery bank reaches the upper or lower limit of the allowable SOC range or is outside the allowable SOC range; A method for determining SOC, which further includes:

10. A method for determining SOC for a battery bank including multiple battery groups, A step of determining a first SOC equal to the average SOC of the plurality of battery groups is included, The following steps are executed when the first SOC is different from the reference SOC or is outside the reference SOC range: A step of determining a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups, depending on whether the battery bank is charging or discharging; A step of determining a first weight and a second weight based on the second SOC; A step of determining a third SOC by applying a first weighted sum operation to the first SOC and the second SOC; and A step of determining the SOC of the battery bank by applying a second weighted sum operation to the third SOC and the previous SOC of the battery bank; A method for determining SOC, which further includes:

11. In paragraph 10, A step of determining the third SOC to be the same as the first SOC when the first SOC is equal to the reference SOC or within the reference SOC range; A method for determining SOC, which further includes:

12. In paragraph 10, The step of determining the SOC of the above battery bank is: A step of determining a third weight and a fourth weight based on the difference between the third SOC and the previous SOC of the battery bank; and A step of determining the SOC of the battery bank by individually applying the third weight and the fourth weight to the third SOC and the previous SOC of the battery bank; A method for determining SOC, including:

13. In a SOC determination device for a battery bank including multiple battery groups, A processor comprising: a processor that determines a first SOC equal to an average SOC of the plurality of battery groups; The above processor, when the first SOC is different from the reference SOC or is outside the reference SOC range, performs the following operations: An operation of determining a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups, depending on whether the battery bank is charging or discharging; and A SOC determination device configured to execute an operation of determining the SOC of the battery bank by applying a weighted sum operation to the first SOC and the second SOC.

14. In a SOC determination device for a battery bank including multiple battery groups, A processor comprising: a processor that determines a first SOC equal to an average SOC of the plurality of battery groups; The above processor, when the first SOC is different from the reference SOC or is outside the reference SOC range, performs the following operations: An operation of determining a second SOC equal to the maximum SOC or minimum SOC of the plurality of battery groups, depending on whether the battery bank is charging or discharging; An operation of determining a third SOC by applying a first weighted sum operation to the first SOC and the second SOC; and An SOC determination device configured to execute an operation of determining the SOC of the battery bank by applying a second weighted sum operation to the third SOC and the previous SOC of the battery bank.

15. A battery system comprising a SOC determination device according to claim 13 or 14.

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