Device and method for estimating SOC of battery

Abstract

A device for estimating an SOC of a battery, according to an embodiment of the present invention, may comprise: at least one processor; and a memory storing at least one instruction that is executed through the at least one processor. The at least one instruction may comprise instructions to: identify whether a state of charge (SOC) at a previous time point is included in a predefined plateau; when the SOC at the previous time point is included in the plateau, estimate an SOC at the current time point by using a predefined first SOC estimation algorithm; when the SOC at the previous time point is not included in the plateau, identify whether an open circuit voltage (OCV) at the current time point is included in the plateau; and estimate the SOC at the current time point by using a predefined second SOC estimation algorithm.

Description

Battery SOC Estimation Device and Method

[0001] The present application claims the benefit of the filing date of Korean Patent Application No. 10-2025-0050619 filed with the Korean Intellectual Property Office on April 18, 2025, and all contents disclosed in the document of said Korean patent application are incorporated into this specification.

[0002] The present invention relates to a battery SOC estimation apparatus and method, and more specifically, to a battery SOC estimation apparatus and method for estimating the SOC of a battery having a voltage flat region.

[0003] Secondary batteries are batteries that can be reused through charging even after discharge, and can be used as an energy source for small devices such as mobile phones, tablet PCs, and vacuum cleaners, and are also used as an energy source for medium and large devices such as automobiles and Energy Storage Systems (ESS) for smart grids.

[0004] Secondary batteries are applied to the system in the form of assemblies, such as battery modules in which multiple battery cells are connected in series and parallel, or battery packs in which battery modules are connected in series and parallel, depending on the system's requirements.

[0005] Carbon materials are mainly used as negative electrode active materials for lithium secondary batteries, and lithium-containing cobalt oxide (LiCoO2) is mainly used as positive electrode active materials; additionally, the use of lithium-containing manganese oxide (LiMnO2, LiMn2O4, etc.) and lithium-containing nickel oxide (LiNiO2) is also being considered.

[0006] Recently, lithium iron phosphate (LiFePO4)-based compounds have been used as cathode active materials for lithium-ion batteries. Lithium Iron Phosphate (LFP) batteries, which utilize lithium iron phosphate as the cathode active material, are superior to other batteries in terms of thermal stability and cost-efficiency. However, LFP batteries exhibit flat characteristics with a voltage plateau in the charge characteristic curve (the relationship between open-circuit voltage and SOC), and there is a problem in that the State of Charge (SOC) cannot be accurately estimated during this plateau region.

[0007] A related prior art is KR 10-2023-0115117 A.

[0008] The objective of the present invention, which aims to solve the above-mentioned problems, is to provide a battery SOC estimation device for more accurately estimating the SOC of a battery having a voltage flat region.

[0009] Another objective of the present invention to solve the above-mentioned problems is to provide a battery SOC estimation method using such a battery SOC estimation device.

[0010] Another objective of the present invention to solve the above-mentioned problems is to provide a battery system including such a battery SOC estimation device.

[0011] A battery SOC estimation device according to one embodiment of the present invention for achieving the above objective may include at least one processor; and a memory that stores at least one instruction executed through the at least one processor.

[0012] The above at least one command may include: a command to check whether the State of Charge (SOC) at a previous time point is included in a predefined flat interval; a command to estimate the State of Charge at a current time point using a predefined first SOC estimation algorithm if the State of Charge at the previous time point is included in the flat interval; a command to check whether the Open Circuit Voltage (OCV) at a current time point is included in the flat interval if the State of Charge at the previous time point is not included in the flat interval; and a command to estimate the State of Charge at a current time point using a predefined second SOC estimation algorithm if the Open Circuit Voltage at a current time point is not included in the flat interval.

[0013] The flat section above can be defined as an SOC range and an OCV range in which, in the correspondence curve between the SOC and OCV of the battery, the change in OCV relative to the change in SOC is below a predetermined threshold value.

[0014] The above at least one command may further include a command to estimate either the lower or upper limit value of the SOC range defined by the flat section as the SOC at the current time when the OCV at the current time is included in the flat section.

[0015] A command to estimate either the lower or upper limit value of the above SOC range as the SOC at the current point in time may include a command to estimate the value among the lower or upper limit values ​​of the above SOC range that is closer to the SOC at the previous point in time as the SOC at the current point in time.

[0016] A command to check whether the OCV at the current time point is included in the flat section may include: a command to check whether the SOC at the previous time point is either the lower limit value or the upper limit value; and, if the SOC at the previous time point is not the upper limit value and the lower limit value, a command to check whether the OCV at the current time point is included in the flat section.

[0017] A command to check whether the OCV at the current time point is included in the flat section may include: a command to check whether the current direction at the current time point is the same as the current direction at the previous time point when the SOC at the previous time point is either the lower limit value or the upper limit value; and a command to check whether the OCV at the current time point is included in the flat section when the current direction at the current time point is the same as the current direction at the previous time point.

[0018] The above at least one command may further include a command to estimate the SOC at the current time point using the second SOC estimation algorithm when the current direction at the current time point is different from the current direction at the previous time point.

[0019] The above first SOC estimation algorithm may be a current integration-based SOC estimation algorithm.

[0020] The above second SOC estimation algorithm may be an EKF (Extended Kalman Filter) based SOC estimation algorithm.

[0021]

[0022] A battery SOC estimation method according to an embodiment of the present invention for achieving the above other objectives may include: a step of checking whether the SOC (State of Charge) at a previous time point is included in a predefined flat section; a step of estimating the SOC at a current time point using a predefined first SOC estimation algorithm if the SOC at the previous time point is included in the flat section; a step of checking whether the OCV (Open Circuit Voltage) at a current time point is included in the flat section if the SOC at the previous time point is not included in the flat section; and a step of estimating the SOC at a current time point using a predefined second SOC estimation algorithm if the OCV at a current time point is not included in the flat section.

[0023] The battery SOC estimation method described above may further include the step of estimating either the lower limit value or the upper limit value of the SOC range defined by the flat section as the SOC at the current time point when the OCV at the current time point is included in the flat section.

[0024] The step of estimating either the lower or upper limit value of the above SOC range as the SOC at the current time point may include the step of estimating the value among the lower or upper limit values ​​of the above SOC range that is close to the SOC at the previous time point as the SOC at the current time point.

[0025] The step of determining whether the OCV at the current time point is included in the flat section may include: a step of determining whether the SOC at the previous time point is either the lower limit value or the upper limit value; and, if the SOC at the previous time point is not the upper limit value and the lower limit value, a step of determining whether the OCV at the current time point is included in the flat section.

[0026] The battery SOC estimation method described above may include a step of determining whether the OCV at the current time is included in the flat section, wherein if the SOC at the previous time is either the lower limit value or the upper limit value, the step of determining whether the current direction at the current time is the same as the current direction at the previous time; and if the current direction at the current time is the same as the current direction at the previous time, the step of determining whether the OCV at the current time is included in the flat section.

[0027] The battery SOC estimation method described above may further include a step of estimating the SOC at the current time point using the second SOC estimation algorithm when the current direction at the current time point is different from the current direction at the previous time point.

[0028]

[0029] A battery system according to one embodiment of the present invention for achieving the above-mentioned other purpose may include: a battery; and a battery SOC estimation device that estimates the State of Charge (SOC) of the battery at predefined unit times using state data of the battery. Here, the battery SOC estimation device may estimate the SOC at a current time point using a predefined first SOC estimation algorithm when the SOC at a previous time point is included in a predefined flat section, and estimate the SOC at a current time point using a predefined second SOC estimation algorithm when the SOC at the previous time point is not included in the flat section and the OCV at the current time point is not included in the flat section.

[0030] The battery SOC estimation device can estimate either the lower limit value or the upper limit value of the SOC range defined as the flat section as the SOC at the current point in time, until the OCV of the battery moves out of the flat section, when the SOC at the previous point in time is not included in the flat section and the OCV at the current point in time is included in the flat section.

[0031] The battery SOC estimation device can estimate the value closest to the SOC at the previous point in time as the SOC at the current point in time among the lower or upper limit values ​​of the SOC range.

[0032] According to the embodiment of the present invention as described above, the SOC of a battery having a voltage flat section can be estimated more accurately.

[0033] Figure 1 is a block diagram of a typical energy storage system.

[0034] Figure 2 shows the charging characteristic curve of an LFP battery.

[0035] FIG. 3 is a block diagram of a battery system according to an embodiment of the present invention.

[0036] Figure 4 is a graph for explaining a flat section according to an embodiment of the present invention.

[0037] FIG. 5 is a flowchart of the operation of a battery SOC estimation method according to an embodiment of the present invention.

[0038] FIG. 6 is a graph illustrating a battery SOC estimation method according to an embodiment of the present invention.

[0039] FIG. 7 is a flowchart of the operation of a battery SOC estimation method according to another embodiment of the present invention.

[0040] FIG. 8 is a graph illustrating a battery SOC estimation method according to another embodiment of the present invention.

[0041] FIG. 9 is a block diagram of a battery SOC estimation device according to an embodiment of the present invention.

[0042] 100: Battery

[0043] 200, 900: Battery SOC Estimator

[0044] The present invention is susceptible to various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing.

[0045] Terms such as first, second, A, B, etc., may be used to describe various components, but said components shall not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0046] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0047] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0048] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0049]

[0050] Some terms used in this specification are defined as follows.

[0051] A battery cell is the smallest unit that performs the role of storing power, and a battery module refers to an assembly of multiple battery cells that are electrically connected.

[0052] A battery rack refers to a single-structure system that electrically connects module units set by a battery manufacturer and enables monitoring and control through a Battery Management System (BMS), and may be configured to include multiple battery modules (or battery packs) and one BPU or protection device.

[0053] A battery bank may refer to a group of large-scale battery rack systems configured by connecting multiple battery racks in parallel. Monitoring and control of a rack BMS (RBMS) at the battery rack level can be performed through a battery bank-level BMS.

[0054] A battery assembly refers to a collection comprising a plurality of electrically connected battery cells that is applied to a specific system or device and functions as a power source. Here, a battery assembly may refer to a battery module, a battery pack, a battery rack, or a battery bank, but the scope of the present invention is not limited to these entities.

[0055] A BSC (Battery System Controller) is a device that performs top-level control of a battery system, including a battery bank unit battery system, and is also used as a controller in a battery system with multiple bank-level structures.

[0056] SOC (State of Charge) is the battery's current charged state expressed as a percentage, and SOH (State of Health) is the battery's current remaining state expressed as a percentage.

[0057]

[0058] Figure 1 is a block diagram of a typical energy storage system.

[0059] In an Energy Storage System (ESS), the smallest unit of a battery responsible for storing electricity is typically a battery cell. A series or parallel combination of battery cells forms a battery pack, and multiple battery packs can constitute a battery rack. In other words, a battery rack can serve as the smallest unit of a battery system through a series or parallel combination of battery packs. Here, depending on the device or system in which the battery is used, a battery pack may also be referred to as a battery module.

[0060] Referring to FIG. 1, a battery rack may include a plurality of battery packs and one BPU (50) or protection device. The battery rack can be monitored and controlled through an RBMS (Rack BMS). The RBMS can monitor the current, voltage, and temperature of each battery pack it manages, calculate the State of Charge (SOC) of the battery based on the monitoring results, and control charging and discharging.

[0061] Meanwhile, the battery protection device (BPU) (50) is a device for protecting the battery from abnormal current and fault current at the battery rack level. The BPU may include a main contactor (MC), a fuse, a circuit breaker (CB), or a disconnect switch (DS). The BPU can control the battery system at the rack level by controlling the main contactor on / off according to the control of the RBMS. The BPU can also protect the battery from short-circuit current using a fuse in the event of a short circuit. In this way, the existing battery system can be controlled through protection devices such as the BPU and switchgear.

[0062] Meanwhile, a Battery System Controller (BSC) (20) is installed in each battery section configured to include multiple batteries, peripheral circuits, devices, etc., so that it can monitor and control control targets such as voltage, current, temperature, and circuit breakers. The BSC is the top-level control device of a battery system including a bank-unit battery system containing multiple battery packs, and is also used as a control device in a battery system with multiple bank-level structures. Here, each bank-level battery system may include a Bank BMS, and the BBMS can perform monitoring and control for each of the racks by linking with the RBMSs of the battery racks it manages.

[0063] Additionally, a Power Conversion System (PCS) (40) installed in each battery section controls the charging and discharging of the battery by controlling the power supplied from the outside and the power supplied from the battery section to the outside, and may include a DC / AC inverter. Meanwhile, if the ESS system is linked with a PV (Photovoltaic; solar power generation system) module farm (70), it may include a PV inverter.

[0064] Meanwhile, the output of each BPU can be connected to the PCS (40) via a DC bus, and the PCS (40) can be connected to the grid (60). In addition, the EMS (Energy Management System) / PMS (Power Management System) (30) manages the ESS system as a whole.

[0065]

[0066] Figure 2 shows the charging characteristic curve of an LFP battery.

[0067] More specifically, FIG. 2 shows the charging characteristic curve of an LFP (Lithium Iron Phosphate) battery in which lithium iron phosphate is used as the positive electrode active material. The charging characteristic curve shows the correspondence between the Open Circuit Voltage (OCV) and the State of Charge (SOC) measured during the battery charging process.

[0068] Referring to FIG. 2, the charge characteristic curve of an LFP battery has a voltage plateau in the range of approximately 10% to approximately 90% SOC. To estimate the SOC of a battery having such voltage plateau characteristics, multiple SOC estimation techniques can be utilized.

[0069] For example, the current integration-based SOC estimation method measures the current flowing through the battery using a current sensor and estimates the battery's SOC based on the current integration value accumulated over time. Additionally, the EKF (Extended Kalman Filter)-based SOC estimation method predicts the battery's state value based on input values ​​including the battery's current and estimates the battery's state value based on the predicted state value and measured values ​​including the battery's voltage; this method offers relatively higher estimation accuracy than the current integration-based SOC estimation method.

[0070] To estimate the SOC of a battery with flat voltage characteristics, a current integration-based SOC estimation method is applied in the flat region, and an EKF (Extended Kalman Filter) based SOC estimation method can be applied in the non-flat region.

[0071] However, the accuracy of SOC estimation based on the current integration method may decrease due to measurement errors of current sensors and differences in state between batteries; if battery charging and discharging continue within a flat range, the estimation error (the difference between the estimated SOC and the actual SOC) may accumulate and increase.

[0072] The present invention, devised to solve these problems, relates to a battery SOC estimation device and method capable of minimizing the estimation error of SOC.

[0073] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0074]

[0075] FIG. 3 is a block diagram of a battery system according to an embodiment of the present invention.

[0076] Referring to FIG. 3, a battery system according to an embodiment of the present invention may include one or more batteries (100) and a battery SOC estimation device (200) (hereinafter, SOC estimation device).

[0077] In the present invention, the battery (100) may mean a battery cell or a battery assembly. For example, the battery (100) may correspond to a battery cell, a battery module, a battery pack, or a battery bank.

[0078] The battery (100) may correspond to a battery cell (e.g., an LFP battery cell) having at least a portion of the voltage flat section in the charge characteristic curve, or a battery assembly including such a battery cell.

[0079] The SOC estimation device (200) corresponds to a battery management device, a battery control device, or an energy management device included in a battery system, or may be implemented by being included in one or more of these. For example, the SOC estimation device (200) corresponds to a BMS, a BSC, an EMS, or a PMS, or may be implemented by being included in one of these.

[0080] The SOC estimation device (200) can collect state data for the battery (100) and estimate the SOC of the battery (100) using the collected state data. Here, the SOC estimation device (200) can collect state data for the battery (100) at a predetermined unit time (e.g., 1 second) and estimate the SOC of the battery (100) at a predetermined unit time using the collected state data. The SOC estimation device (200) can store the estimated SOC at a unit time in a storage device or memory.

[0081] The state data of the battery (100) may include the battery's current, voltage, OCV, temperature, and internal resistance.

[0082] The SOC estimation device (200) can estimate the SOC for each of the batteries (100) or estimate the SOC of the battery system unit using the state data of each of the batteries (100).

[0083] A storage device or memory of the SOC estimation device (200) may store an SOC estimation algorithm that receives battery state data and outputs an SOC estimation value. Here, various SOC estimation algorithms, such as a current integration method-based SOC estimation algorithm and an EKF (Extended Kalman Filter)-based SOC estimation algorithm, may be stored in the storage device or memory.

[0084] Information regarding a flat section may be pre-stored in the storage device or memory of the SOC estimation device (200). Here, the flat section may be defined as an SOC range and an OCV range in which, in the correspondence curve between the SOC and OCV of the battery, the change in OCV relative to the change in SOC is less than or equal to a predetermined threshold value.

[0085] FIG. 4 is a graph for explaining a flat section according to an embodiment of the present invention. For example, as shown in FIG. 4, the flat section may be defined as an SOC range greater than SOCa and less than SOCb, and an OCV range greater than Va and less than Vb. Here, flat section information in a format such as [(SOC lower limit_SOCa), (SOC upper limit_SOCb), (OCV lower limit_Va), (OCV upper limit_Vb)] may be stored in the storage device or memory of the SOC estimation device (200).

[0086] Referring again to FIG. 3, the SOC estimation device (200) is the SOC of a previous point in time (SOC t-1 ) and the current OVC (OCV t Based on ), the current SOC (SOC t ) can be estimated. Here, the SOC estimation device (200) is, SOC t-1 Whether it is included in a predefined flat interval, and OCV t Determine whether it is included in the flat section, and based on the determination result, SOC t Select an SOC estimation algorithm to estimate, or SOC t It can be estimated as a specific predefined value.

[0087] More specifically, the SOC estimation device (200) is, SOC t-1 If it falls within a predefined flat interval (greater than SOCa, less than SOCb), using a predefined first SOC estimation algorithm (e.g., a current integration-based SOC estimation algorithm), SOCt It can be estimated. Also, SOC t-1 It is not included in the flat section (SOCa greater than, SOCb less than), and OCV t If it is not included in the flat section (Va greater than Vb less than), the SOC estimation device (200) uses a predefined second SOC estimation algorithm (e.g., an EKF-based SOC estimation algorithm) to estimate the SOC t It can be estimated.

[0088] If, SOC t-1 Although it is not included in the flat zone (SOCa greater than, SOCb less than), OCV t If it is included in a flat section (Va greater than Vb less than), the SOC estimation device (200) determines either the lower limit value (SOCa) or the upper limit value (SOCb) of the SOC range until the OCV of the battery exits the flat section, SOC t It can be estimated as follows. Here, the SOC estimation device (200) is, among the lower limit value (SOCa) or upper limit value (SOCb) of the SOC range, SOC t-1 SOC with a value close to t It can be estimated as.

[0089] That is, the SOC estimation device (200) is, SOC t-1 If it is included in the flat section, the SOC is calculated using the first SOC estimation algorithm. t Estimate and SOC t-1 If it is not included in the flat section, the second SOC estimation algorithm is not applied immediately, and the OCV calculated based on the actual voltage value is used. t You can additionally check whether it is included in the flat section. OCV t If the curve is not included in the flat section, the SOC estimation device (200) uses the second SOC estimation algorithm to estimate the SOC t Estimate and OCV t If it is included in the flat section, the SOC estimation algorithm is not applied, and SOCt-1 The boundary value of the SOC range close to SOC t It can be estimated as.

[0090] According to such embodiments of the present invention, SOC t-1 Although it is not included in the flat section, OCV t When the battery is included in a flat region, the estimated SOC value can be fixed at the SOC boundary value of the flat region until the battery's OCV moves out of the flat region. Accordingly, during the period when the estimated SOC value is fixed, the difference between the estimated SOC value and the actual SOC value can gradually decrease. Furthermore, when the battery's OCV moves out of the flat region, the estimated SOC value becomes identical to the actual SOC value, so the battery's SOC can be estimated with high accuracy thereafter.

[0091]

[0092] FIG. 5 is a flowchart of the operation of a battery SOC estimation method according to an embodiment of the present invention.

[0093] The battery SOC estimation method according to an embodiment of the present invention can be performed by an SOC estimation device.

[0094] The SOC estimation device uses the SOC of a previous point in time stored in memory or storage device (SOC t-1 ) can be checked (S510).

[0095] Subsequently, the SOC estimation device, SOC t-1 It can be checked whether it falls within a predefined flat range (SOCa greater, SOCb less) (S520).

[0096] SOC t-1 If it falls within a flat interval (SOCa greater than, SOCb less than) (Y of S520), the SOC estimation device uses a predefined first SOC estimation algorithm to determine the SOC of the current time point (SOC t) can be estimated (S530). Here, the first SOC estimation algorithm may be a current integration-based SOC estimation algorithm.

[0097] SOC t-1 If it is not included in the flat section (N of S520), the SOC estimation device, the OCV at the current time (OCV t It can be checked whether ) is included in the flat interval (Va greater than Vb less than Vb) (S540). Here, OCV t may be an open-circuit voltage value calculated based on the voltage measurement value (Vt) at the current time.

[0098] OCV t If it falls within the flat section (greater than Va and less than Vb) (Y in S540), the SOC estimation device takes either the lower limit value (SOCa) or the upper limit value (SOCb) of the SOC range, SOC t It can be estimated as (S550). Here, the SOC estimation device, among the lower limit value (SOCa) or upper limit value (SOCb) of the SOC range, SOC t-1 SOC with a value close to t It can be estimated as.

[0099] OCV t If it is not included in the flat interval (Va greater than Vb less than Vb) (N of S540), the SOC estimation device uses a predefined second SOC estimation algorithm to scalar the SOC t It can be estimated (S560). Here, the second SOC estimation algorithm may be an EKF-based SOC estimation algorithm.

[0100] The SOC estimation device estimates the SOC according to any one of steps S530, S550, and S560. t It can be stored in memory or a storage device (S570).

[0101] SOC tWhen storage is complete, the SOC estimation device may start step S510 to estimate the SOC at the next time point. Here, the estimated SOC value at the current time point may be used to estimate the SOC at the next time point.

[0102]

[0103] FIG. 6 is a graph illustrating a battery SOC estimation method according to an embodiment of the present invention.

[0104] If the charging and discharging of the battery continues within a flat range (SOCa greater than SOCb less than SOC), the difference between the SOC estimated value estimated by the first SOC estimation algorithm and the actual value may accumulate.

[0105] At point A, SOC t-1 If it deviates from the flat region (greater than SOCa and less than SOCb), the SOC estimation device does not immediately apply the second SOC estimation algorithm, but instead uses the OCV calculated based on the actual voltage measurement value. t You can check whether it is included in the flat section (greater than Va, less than Vb). OCV t If it falls within the flat section (greater than Va, less than Vb), the SOC estimation device, SOC t-1 SOCb, the boundary value of the SOC range close to SOC, is SOC t It can be estimated as.

[0106] Afterwards, the estimated SOC value can be fixed at SOCb until the battery's OCV moves out of the flat range.

[0107] At time B, OCV t If it deviates from the flat region (greater than Va, less than Vb), the SOC estimation device uses the second SOC estimation algorithm to SOC t It can estimate. Subsequently, the SOC estimation device, SOC t-1 Until it enters the flat section, use the second SOC estimation algorithm to SOC t It can be estimated.

[0108] During the period from A to B, the difference between the estimated SOC value and the actual SOC value can gradually decrease, and at point B, the estimated SOC value becomes identical to the actual SOC value, so the battery's SOC can be estimated with high accuracy after point B.

[0109]

[0110] FIG. 7 is a flowchart of the operation of a battery SOC estimation method according to another embodiment of the present invention.

[0111] The SOC estimation device is the SOC stored in memory or storage device. t-1 You can check (S710).

[0112] Subsequently, the SOC estimation device, SOC t-1 It can be checked whether it falls within a predefined flat range (SOCa greater, SOCb less) (S720).

[0113] SOC t-1 If it falls within a flat interval (greater than SOCa, less than SOCb) (Y in S720), the SOC estimation device uses a predefined first SOC estimation algorithm, SOC t It can be estimated (S730). Here, the first SOC estimation algorithm may be a current integration-based SOC estimation algorithm.

[0114] SOC t-1 If it is not included in the flat section (N of S720), the SOC estimation device, SOC t-1 It can be checked whether the SOC is either the lower limit value (SOCa) or the upper limit value (SOCb) of the flat section (S740). That is, the SOC estimation device can check whether the SOC estimated at the previous time point (t-1) was estimated by the first and second SOC estimation algorithms, or whether it is a fixed value (SOCa or SOCb).

[0115] SOC t-1If is not the lower SOC limit value (SOCa) and the upper SOC limit value (SOCb) (N in S740), the SOC estimation device, OCV t It can be checked whether it is included in the flat section (Va greater than Vb less than Vb) (S750). Here, OCV t may be an open-circuit voltage value calculated based on the voltage measurement value (Vt) at the current time.

[0116] OCV t If it falls within the flat section (greater than Va and less than Vb) (Y of S750), the SOC estimation device takes either the lower limit value (SOCa) or the upper limit value (SOCb) of the SOC range, SOC t It can be estimated as (S760). Here, the SOC estimation device, among the lower limit value (SOCa) or upper limit value (SOCb) of the SOC range, SOC t-1 SOC with a value close to t It can be estimated as.

[0117] OCV t If it is not included in the flat interval (Va greater than Vb less than Vb) (N of S750), the SOC estimation device uses a predefined second SOC estimation algorithm to estimate the SOC t It can be estimated (S780).

[0118] SOC t-1 If is either the lower SOC limit value (SOCa) or the upper SOC limit value (SOCb) (Y in S740), the SOC estimation device, the current direction at the current time (I t ) is the current direction at the previous point in time (I t-1 It can check whether it is the same as (S770). That is, the SOC estimation device can check whether the battery has switched from charging mode to discharging mode or from discharging mode to charging mode.

[0119] Current direction at the current point in time (I t ) is the current direction at the previous point in time (I t-1In the same case as ) (Y of S770), the SOC estimation device, OCV t It can be checked whether it is included in the flat section (Va greater than Vb less than Vb) (S750).

[0120] Current direction at the current point in time (I t ) is the current direction at the previous point in time (I t-1 In cases different from ) (N of S770), the SOC estimation device uses a predefined second SOC estimation algorithm, SOC t It can be estimated (S780).

[0121] The SOC estimation device estimates the SOC according to any one of steps S730, S760, and S780. t It can be stored in memory or a storage device (S790).

[0122] SOC t When storage is complete, the SOC estimation device may start step S710 to estimate the SOC at the next time point. Here, the estimated SOC value at the current time point may be used to estimate the SOC at the next time point.

[0123]

[0124] FIG. 8 is a graph illustrating a battery SOC estimation method according to another embodiment of the present invention.

[0125] Referring to FIG. 8, a plurality of flat sections are predefined, and information for each of the flat sections can be pre-stored in the storage device or memory of the SOC estimation device.

[0126] For example, as illustrated in FIG. 8, a first flat section defined by an SOC range greater than SOCa1 and less than SOCb1, and an OCV range greater than Va1 and less than Vb1, and a second flat section defined by an SOC range greater than SOCa2 and less than SOCb2, and an OCV range greater than Va2 and less than Vb2 may be predefined.

[0127] In this case, flat section information in a format such as [(first SOC lower limit_SOCa1), (first SOC upper limit_SOCb1), (first OCV lower limit_Va1), (first OCV upper limit_Vb1)], and [(second SOC lower limit_SOCa2), (second SOC upper limit_SOCb2), (second OCV lower limit_Va2), (second OCV upper limit_Vb2)] may be stored in the storage device or memory of the SOC estimation device.

[0128] When multiple flat sections are predefined, the SOC estimation device, SOC t-1 Check whether it is included in any of the predefined flat sections, and SOC t-1 If it is included in a specific flat section, using the predefined first SOC estimation algorithm, SOC t It can be estimated.

[0129] SOC t-1 If it is not included in the flat sections, the SOC estimation device, OCV t You can check whether it is included in any of the flat sections. OCV t If it is included in a specific flat section, the SOC estimation device, either the lower SOC limit or the upper SOC limit of the flat section, SOC t It can be estimated as follows. Here, the SOC estimation device, among the lower SOC limit value or the upper SOC limit value of the corresponding flat section, SOC t-1 SOC with a value close to t It can be estimated as.

[0130] OCV t If it is not included in the flat sections, the SOC estimation device uses a predefined second SOC estimation algorithm, SOC t It can be estimated.

[0131]

[0132] FIG. 9 is a block diagram of a battery SOC estimation device according to an embodiment of the present invention.

[0133] A battery SOC estimation device according to an embodiment of the present invention may correspond to a battery management device, a battery control device, or an energy management device included in a battery system, or may be implemented by being included in one or more of these. For example, the battery SOC estimation device may correspond to a BMS, a BSC, an EMS, or a PMS, or may be implemented by being included in one of these.

[0134] A battery SOC estimation device (900) may include at least one processor (910), a memory (920) that stores at least one instruction executed through the processor, and a transceiver (930) that is connected to a network to perform communication.

[0135] The above at least one command may include: a command to check whether the SOC at a previous time point is included in a predefined flat interval; a command to estimate the SOC at a current time point using a predefined first SOC estimation algorithm if the SOC at the previous time point is included in the flat interval; a command to check whether the Open Circuit Voltage (OCV) at a current time point is included in the flat interval if the SOC at the previous time point is not included in the flat interval; and a command to estimate the SOC at a current time point using a predefined second SOC estimation algorithm if the OCV at a current time point is not included in the flat interval.

[0136] The flat section above can be defined as an SOC range and an OCV range in which, in the correspondence curve between the SOC and OCV of the battery, the change in OCV relative to the change in SOC is below a predetermined threshold value.

[0137] The above at least one command may further include a command to estimate either the lower or upper limit value of the SOC range defined by the flat section as the SOC at the current time when the OCV at the current time is included in the flat section.

[0138] A command to estimate either the lower or upper limit value of the above SOC range as the SOC at the current point in time may include a command to estimate the value among the lower or upper limit values ​​of the above SOC range that is closer to the SOC at the previous point in time as the SOC at the current point in time.

[0139] A command to check whether the OCV at the current time point is included in the flat section may include: a command to check whether the SOC at the previous time point is either the lower limit value or the upper limit value; and, if the SOC at the previous time point is not the upper limit value and the lower limit value, a command to check whether the OCV at the current time point is included in the flat section.

[0140] A command to check whether the OCV at the current time point is included in the flat section may include: a command to check whether the current direction at the current time point is the same as the current direction at the previous time point when the SOC at the previous time point is either the lower limit value or the upper limit value; and a command to check whether the OCV at the current time point is included in the flat section when the current direction at the current time point is the same as the current direction at the previous time point.

[0141] The above at least one command may further include a command to estimate the SOC at the current time point using the second SOC estimation algorithm when the current direction at the current time point is different from the current direction at the previous time point.

[0142] The above first SOC estimation algorithm may be a current integration-based SOC estimation algorithm.

[0143] The above second SOC estimation algorithm may be an EKF (Extended Kalman Filter) based SOC estimation algorithm.

[0144] The battery SOC estimation device (900) may also further include an input interface device (940), an output interface device (950), a storage device (960), etc. Each component included in the battery SOC estimation device (900) may be connected by a bus (970) to communicate with each other.

[0145] Here, the processor (910) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Additionally, the memory may be composed of at least one of a volatile / transitory storage medium and a non-volatile / non-transitory storage medium. For example, the memory may be composed of at least one of a read-only memory (ROM) and a random access memory (RAM), and may include an EEPROM (Electrically Erasable Programmable Read-only Memory).

[0146] The operation of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium may include any type of recording device in which data that can be read by a computer system is stored. The computer-readable recording medium may also be distributed across networked computer systems, so that the computer-readable program or code can be stored and executed in a distributed manner.

[0147] The operation of the method according to an embodiment of the present invention can be implemented in various forms related to the program, such as a computer program or code itself or a computer program product.

[0148] Additionally, computer-readable recording media may include one or more of volatile / transitory recording media and non-volatile / non-transitory recording media.

[0149] Computer-readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory, and may include, for example, various types of servers located on a network. Program instructions may include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

[0150] Some aspects of the invention have been described in the context of a device, but may also be described according to a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described according to a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such a device.

[0151] Although the present invention has been described with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

1. At least one processor; and It includes a memory that stores at least one instruction executed through the above-mentioned at least one processor, and The above at least one command is, A command to check whether the State of Charge (SOC) at a previous point in time falls within a predefined flat interval; A command to estimate the SOC at the current time point using a predefined first SOC estimation algorithm when the SOC at the previous time point is included in the flat section; A command to check whether the Open Circuit Voltage (OCV) at the current time point is included in the flat section when the SOC at the previous time point is not included in the flat section; and A battery SOC estimation device comprising a command to estimate the SOC at a current time using a predefined second SOC estimation algorithm when the OCV at the current time is not included in the flat section.

2. In Claim 1, The above flat section is, A battery SOC estimation device defined by an SOC range and an OCV range, wherein, in the correspondence curve between the SOC and OCV of the battery, the change in OCV relative to the change in SOC is less than or equal to a predetermined threshold value.

3. In Claim 1, The above at least one command is, A battery SOC estimation device further comprising a command to estimate either the lower limit value or the upper limit value of the SOC range defined by the flat section as the SOC at the current time point when the OCV at the current time point is included in the flat section.

4. In Claim 3, An instruction to estimate either the lower or upper value of the above SOC range as the SOC at the current time is, A battery SOC estimation device comprising a command to estimate the value closest to the SOC at the previous point in time as the SOC at the current point in time, among the lower or upper limit values ​​of the SOC range.

5. In Claim 3, A command to check whether the OCV at the current time is included in the flat section is, A command to determine whether the SOC at the aforementioned previous point in time is either the lower limit value or the upper limit value; and A battery SOC estimation device comprising a command to determine whether the OCV at the current time point is included in the flat section when the SOC at the previous time point is not the lower and upper limits.

6. In Claim 5, A command to check whether the OCV at the current time is included in the flat section is, A command to determine whether the current direction at the current time is the same as the current direction at the previous time when the SOC at the previous time is either the lower or upper limit value; and A battery SOC estimation device comprising a command to determine whether the OCV at the current time is included in the flat section when the current direction at the current time is the same as the current direction at the previous time.

7. In Claim 6, The above at least one command is, A battery SOC estimation device further comprising a command to estimate the SOC at the current time point using the second SOC estimation algorithm when the current direction at the current time point is different from the current direction at the previous time point.

8. In Claim 1, The above-mentioned first SOC estimation algorithm is, A battery SOC estimation device, which is a current integration-based SOC estimation algorithm.

9. In Claim 1, The above second SOC estimation algorithm is, Battery SOC estimation device, which is an EKF (Extended Kalman Filter) based SOC estimation algorithm.

10. A step of checking whether the State of Charge (SOC) at a previous point in time falls within a predefined flat interval; If the SOC at the aforementioned previous point in time is included in the flat section, a step of estimating the SOC at the current point in time using a predefined first SOC estimation algorithm; If the SOC at the aforementioned previous point in time is not included in the flat section, a step of checking whether the OCV (Open Circuit Voltage) at the current point in time is included in the flat section; and A battery SOC estimation method comprising the step of estimating the SOC at the current time using a predefined second SOC estimation algorithm when the OCV at the current time is not included in the flat section.

11. In Claim 10, A battery SOC estimation method further comprising the step of estimating either the lower limit value or the upper limit value of the SOC range defined by the flat section as the SOC at the current time when the OCV at the current time is included in the flat section.

12. In Claim 11, The step of estimating either the lower or upper value of the above SOC range as the SOC at the current point in time is: A battery SOC estimation method comprising the step of estimating the value closest to the SOC at the previous point in time as the SOC at the current point in time among the lower or upper limit values ​​of the SOC range.

13. In Claim 11, The step of checking whether the OCV at the current time is included in the flat section is, A step of determining whether the SOC at the aforementioned previous point in time is either the lower limit value or the upper limit value; and A battery SOC estimation method comprising the step of checking whether the OCV at the current time point is included in the flat section when the SOC at the previous time point is not the lower and upper limits.

14. In Claim 13, The step of checking whether the OCV at the current time is included in the flat section is, A step of determining whether the current direction at the current time is the same as the current direction at the previous time when the SOC at the previous time is either the lower limit value or the upper limit value; and A battery SOC estimation method comprising the step of determining whether the OCV at the current time is included in the flat section when the current direction at the current time is the same as the current direction at the previous time.

15. In Claim 14, A battery SOC estimation method comprising the step of estimating the SOC at the current time using the second SOC estimation algorithm when the current direction at the current time is different from the current direction at the previous time.

16. Battery; and A battery SOC estimation device that estimates the State of Charge (SOC) of the battery at predefined unit times using state data of the battery, and The above battery SOC estimation device is, A battery system that estimates the SOC at a current time point using a predefined first SOC estimation algorithm when the SOC at a previous time point is included in a predefined flat section, and estimates the SOC at a current time point using a predefined second SOC estimation algorithm when the SOC at the previous time point is not included in the flat section and the OCV at the current time point is not included in the flat section.

17. In Claim 16, The above battery SOC estimation device is, A battery system that, when the SOC at the previous point in time is not included in the flat section and the OCV at the current point in time is included in the flat section, estimates either the lower limit value or the upper limit value of the SOC range defined as the flat section as the SOC at the current point in time until the OCV of the battery moves out of the flat section.

18. In Claim 17, The above battery SOC estimation device is, A battery system that estimates the value closest to the SOC at the previous point in time as the SOC at the current point in time among the lower or upper limit values ​​of the SOC range.

19. A computer-readable medium storing a program for executing the method of any one of claims 10 to 15 on a computer.

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