Battery connection control method and battery connection control device

Abstract

A battery connection control method and a battery connection control apparatus are provided. The battery connection control method includes the steps of determining an on-line SOC indicating an SOC of at least one battery rack in an on-line state among a plurality of battery racks connectable in parallel between power lines and an off-line SOC indicating an SOC of a target battery rack in an off-line state based on individual state information of the plurality of battery racks; limiting a charge / discharge power of each battery rack in the on-line state if a difference between the on-line SOC and the off-line SOC is less than a threshold SOC; determining an on-line voltage indicating a voltage of at least one battery rack in the on-line state and an off-line voltage of the target battery rack if an elapsed time of the limitation of the charge / discharge power is less than a threshold time; and switching the target battery rack from the off-line state to the on-line state if a difference between the on-line voltage and the off-line voltage is less than a threshold voltage.

Description

Technical Field

[0001] This disclosure relates to techniques for controlling the parallel connection between multiple battery racks to prevent inrush current.

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0139376, filed on October 14, 2024, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] Recently, the demand for portable electronic products such as laptops, cameras or mobile phones has increased rapidly, and with the widespread development of electric vehicles, batteries for energy storage, robots or satellites, much research has been conducted on high-performance batteries that can be repeatedly charged and discharged.

[0004] Batteries on the market now include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among them, compared with nickel-based batteries, lithium batteries have almost no memory effect, and therefore have gained more attention due to their advantages, including free charging and discharging, very low self-discharge rate and high energy density.

[0005] Recently, ensuring high capacity is crucial for stable power management in energy storage systems and electric vehicles. Therefore, in battery packs comprising multiple battery racks installed in parallel, control methods electrically connect at least one of the battery racks between a pair of power lines based on externally required charging / discharging power.

[0006] However, when two or more battery racks are connected in parallel with a voltage difference between them that is not sufficiently small, a surge current, which is a large instantaneous current, may flow. This surge current can cause serious damage to the protective components of the battery racks (e.g., switching units as described below). Summary of the Invention Technical Purpose

[0007] This disclosure is designed to solve the above-mentioned problems, and therefore aims to provide a control method and apparatus for safely connecting an offline battery rack to an online battery rack in parallel among a plurality of battery racks.

[0008] Other objects and advantages of this disclosure will be understood from the following description and will become apparent from the embodiments thereof. Moreover, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof. Technical solution

[0009] A battery connection control method according to one aspect of this disclosure includes: monitoring state information of each of a plurality of battery racks, each of the plurality of battery racks being connectable in parallel between a pair of power lines; determining an online state of charge (SOC) and an offline SOC based on the state information, the online SOC indicating the SOC of at least one battery rack in an online state, and the offline SOC indicating the SOC of a target battery rack, the target battery rack being any of the plurality of battery racks in an offline state; setting a limit on the charging / discharging power of each battery rack in an online state when the difference between the online SOC and the offline SOC is less than a threshold SOC; determining an online voltage and an offline voltage when the elapsed time of the limit on the charging / discharging power is less than a threshold time, the online voltage indicating the voltage of at least one battery rack in an online state, and the offline voltage indicating the voltage of the target battery rack; and switching the target battery rack from an offline state to an online state when the difference between the online voltage and the offline voltage is less than a threshold voltage.

[0010] The battery connection control method may further include: when two or more battery racks are offline, identifying any one of the two or more offline battery racks as the target battery rack based on at least one of the identification code, voltage, and SOC of each of the two or more offline battery racks.

[0011] When only one of multiple battery racks is online, the online SOC can be determined to be equal to the SOC of the only battery rack that is online.

[0012] When two or more battery racks are online, the online SOC can be determined to be equal to the average SOC of the two or more battery racks that are online.

[0013] The battery connection control method may also include eliminating the limitation on the charging / discharging power of each battery rack in the online state after switching the target battery rack from an offline state to an online state.

[0014] The battery connection control method may also include reducing the threshold SOC by a predetermined value when the elapsed time of the limitation on charging / discharging power is equal to or greater than a threshold time.

[0015] The battery connection control method may also include removing the limitation on the charging / discharging power of each battery rack in the online state when the elapsed time of the limitation on the charging / discharging power is equal to or greater than a threshold time.

[0016] The battery connection control method may further include resetting the threshold SOC to a predetermined reference SOC when the difference between the online voltage and the offline voltage is less than a threshold voltage.

[0017] When the difference between the online voltage and the offline voltage is equal to or greater than the threshold voltage, the charging / discharging power can be limited.

[0018] According to an embodiment of the present disclosure, a computer-readable medium may have a program recorded thereon for causing a computer to perform a battery connection control method.

[0019] According to another aspect of this disclosure, a battery connection control device includes: a monitoring unit configured to monitor state information of each of a plurality of battery racks, each of the plurality of battery racks being connectable in parallel between a pair of power lines; and a controller. The controller is configured to determine an online state of charge (SOC) and an offline SOC based on the state information, the online SOC indicating the SOC of at least one of the plurality of battery racks in an online state, and the offline SOC indicating the SOC of a target battery rack, which is any of the plurality of battery racks in an offline state. The controller is configured to set a limit on the charging / discharging power of each battery rack in the online state when the difference between the online SOC and the offline SOC is less than a threshold SOC. The controller is configured to determine an online voltage and an offline voltage when the elapsed time for the limit on the charging / discharging power is less than a threshold time, the online voltage indicating the voltage of at least one battery rack in the online state, and the offline voltage indicating the voltage of the target battery rack. The controller is configured to switch the target battery rack from an offline state to an online state when the difference between the online voltage and the offline voltage is less than a threshold voltage.

[0020] The controller can also be configured to remove the charging / discharging power limitation for each battery rack in the online state after switching the target battery rack from offline to online state.

[0021] The controller can also be configured to reduce the threshold SOC by a predetermined value when the elapsed time of the limit on the charging / discharging power is equal to or greater than the threshold time.

[0022] The controller can also be configured to remove the charging / discharging power limit for each battery rack that is online when the elapsed time of the charging / discharging power limit is equal to or greater than a threshold time.

[0023] The controller can also be configured to reset the threshold SOC to a predetermined reference SOC when the difference between the online voltage and the offline voltage is less than a threshold voltage.

[0024] According to another aspect of this disclosure, an energy storage system includes a battery connection control device. Technical effect

[0025] According to at least one embodiment of this disclosure, the risk of surge current flowing through a battery rack that is offline among a plurality of battery racks can be reduced when the battery racks that are already online are connected in parallel.

[0026] Furthermore, according to at least one embodiment of this disclosure, a first connection condition is met based on the SOC of the battery holder in an offline state and the SOC of the battery holder in an online state. Figure 5 After step S530, it is determined whether the second connection condition based on the voltage of the battery rack in the offline state and the voltage of the battery rack in the online state is met. Figure 5 By taking into account the difference between open-circuit voltage (OCV) and closed-circuit voltage (CCV) in step S560, safe parallel connection control can be achieved.

[0027] Furthermore, according to at least one embodiment of this disclosure, when the voltage difference between the battery rack in the offline state and the battery rack in the online state is not sufficiently small, even though the charging / discharging power of the battery rack in the online state is limited for a predetermined time or longer, by strengthening the enforcement condition of the charging / discharging power limiting function (reducing the 'threshold SOC' in step S580), it is possible to prevent the charging / discharging power limiting function from being performed on each battery rack in the online state more frequently than required, or to prevent the charging / discharging power from being limited for a long time.

[0028] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand these and other effects from the appended claims. Attached Figure Description

[0029] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the following detailed description, are intended to provide a better understanding of the various technical aspects of the present disclosure; therefore, the present disclosure should not be construed as limited to any of the drawings.

[0030] Figure 1 This is a schematic diagram illustrating the architecture of an energy storage system according to this disclosure.

[0031] Figure 2 It is shown schematically. Figure 1 The diagram shows the connection relationships between the components of the energy storage system.

[0032] Figure 3 and Figure 4 This diagram is used as a reference when describing the situation where inrush current occurs between multiple battery racks.

[0033] Figure 5 This is a schematic flowchart illustrating a battery connection control method according to the present disclosure.

[0034] Figure 6 This is a schematic illustration of what may be included in Figure 5 The flowchart shows an example of the routine group in step S520. Detailed Implementation

[0035] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but should be interpreted based on their meanings and concepts corresponding to the various technical aspects of the present disclosure, on the basis of allowing the inventors to appropriately define the terms for the best interpretation.

[0036] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are embodiments of the present disclosure used to describe various technical aspects of the present disclosure and are not intended to be limiting. It should be understood that various other equivalents and modifications can be made thereto when this application is filed.

[0037] Ordinal terms such as “first” and “second” are used to distinguish one element from another among various elements, but are not intended to restrict elements by terminology.

[0038] Unless the context clearly indicates otherwise, the terms "comprising" and "including," when used in this specification, specify the presence of the stated element but do not exclude the presence or addition of one or more other elements. Furthermore, as used herein, the term "unit" refers to at least one processing element that performs at least one function or operation and can be implemented individually or in combination by hardware and software.

[0039] Furthermore, throughout this specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or there may be an intermediary element.

[0040] Figure 1 This is a schematic diagram illustrating the architecture of the energy storage system 1 according to this disclosure, and Figure 2 It is shown schematically. Figure 1 The diagram shows the connection relationships between the components of the energy storage system 1.

[0041] refer to Figure 1 and Figure 2 The energy storage system 1 includes a battery pack BB, a power conversion system 10, and a battery connection control device 100. m is a natural number of 2 or greater.

[0042] Battery pack BB includes multiple battery racks BR1~BR m Multiple battery holders BR1~BR mEach of these can be connected to the power conversion system 10 via a pair of power lines P+, P-. In this specification, multiple battery racks BR1~BR m In the shared descriptions, the symbol 'BR' or 'BR' i 'Attached to the battery holder. i is a natural number equal to or less than m.'

[0043] The power conversion system 10 is electrically connected to multiple battery racks BR1~BR m Between the power grid 2 and / or the electrical load 3.

[0044] The power conversion system 10 uses a DC-AC inverter and / or DC-DC converter included in the power conversion system 10 to handle multiple battery racks BR1~BR1. m Between and / or multiple battery racks BR1~BR2 and the power grid 2 m Power transfer between the power grid and the electrical load 3. That is, when in battery charging mode, the power conversion system 10 can convert AC power (or DC power of different levels) from the power grid 2 into DC power and supply it to the multiple battery racks BR1~BR2. m .

[0045] When in battery discharge mode, the power conversion system 10 can convert power from multiple battery racks BR1 to BR2. m The DC power input from at least one discharge battery rack is converted into AC power (or DC power of a different level) and supplied to the power grid 2 and / or electrical load 3.

[0046] The battery connection control device 100 can receive power information from the power conversion system 10. This power information can indicate the charging or discharging power requested by the power grid 2 and / or the electrical load 3.

[0047] Battery connection control device 100 can acquire instructions for multiple battery racks BR1~BR m The system obtains the state information of each state and transmits charging request signals, discharging request signals, and / or standby request signals to the power conversion system 10 based on the obtained state information. When the power conversion system 10 receives a charging request signal, it can operate in battery charging mode. When the power conversion system 10 receives a discharging request signal, it can operate in battery discharging mode.

[0048] The charging request signal is a request to charge multiple battery racks BR1~BR m At least one of the signals supplying DC power. The discharge request signal is a request to discharge power from multiple battery racks BR1~BR2. mAt least one of the signals that draws DC power. The standby request signal is a signal that requests the cessation of charging and discharging operations.

[0049] Battery rack BR i Includes battery packs (BG) connected in series. i and switching unit SW i .

[0050] Battery Grouping BG i Includes at least one battery cell BC. When the battery group BG i When multiple battery cells BC are included, these multiple battery cells BC can be connected in series, in parallel, or both. In this specification, a battery cell BC refers to the basic unit of a battery that can be charged / discharged independently, and is not limited to a specific type, and can include any rechargeable cell, such as a lithium-ion cell.

[0051] Switching unit SW i Not limited to a specific type, and may include on / off battery groups (BGs). i Any type of switch, such as a switching unit SW, in the current path between the power conversion system 10 and the power conversion system 10. i This can include semiconductor switches such as metal-oxide-semiconductor field-effect transistors (MOSFETs) or mechanical switches such as relays.

[0052] When multiple switching units SW1~SW are turned on / off m In each of these, multiple battery racks BR1~BR m Any two or more can be connected in parallel between a pair of power lines P+ and P-.

[0053] When the switching unit SW is activated i At that time, battery group BG i It can be electrically connected between a pair of power lines, and this state can be referred to as 'online state'. Therefore, when multiple battery racks BR1~BR m When two or more battery racks (e.g., BR1, BR2, BR3) are online, it can indicate that two or more battery racks (e.g., BR1, BR2, BR3) are electrically connected in parallel. When the battery group (BG) is online... i When online, the battery group (BG) i It can be charged and discharged. Even with battery packs (BG) i When the power conversion system 10 stops operating, the battery group BG is in an online state. i Charging and discharging can also be stopped.

[0054] Conversely, when the switching unit SW is disconnected iAt that time, battery group BG i It can be electrically isolated from a pair of power lines, and this state can be referred to as 'offline state'. When the battery group BG... i When offline, even if the power conversion system 10 operates in charging or discharging mode, the battery pack BG i Charging or discharging is also impossible.

[0055] In this manual, a battery rack that is in an online state may be referred to as an 'online rack', and a battery rack that is in an offline state may be referred to as an 'offline rack'.

[0056] Battery connection control device 100 can be configured to perform one or more control functions to prevent multiple battery racks BR1~BR m The surge current that may flow when at least two of them are connected in parallel.

[0057] The battery connection control device 100 includes an information monitoring unit 110 and a controller 120.

[0058] The information monitoring unit 110 has multiple sensing units SU1~SU1. m Multiple sensing units SU1~SU m Set to monitor multiple battery racks BR1~BR separately m The state.

[0059] Multiple sensing units SU1~SU m Each of these includes a voltage measurement circuit VS and a current sensor CS.

[0060] Voltage measurement circuit VS and battery grouping BG i Parallel connection to measure battery group BG i The voltage across the terminals (called 'rack voltage' or 'pack voltage'). Additionally, the voltage measurement circuit VS can measure the battery pack BG. i The voltage of each battery cell BC (referred to as 'cell voltage').

[0061] The current sensor CS is installed in the battery group BG i Connected to the switching unit SW i On the rack line, to measure the flow of BR through the battery rack i The current. Sensing unit SU i Generate sensing signals indicating the measured voltage and current. The sensing signals can refer to pairs of voltage and current values ​​detected simultaneously.

[0062] Controller 120 can be operatively coupled to multiple switching units SW1~SW m Each of the information monitoring unit 110 and the power conversion system 10. In this case, operably coupled means a wired and / or wireless connection that enables the transmission and reception of signals in one or both directions.

[0063] The controller 120 may be implemented in hardware using at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electronic unit for performing other functions.

[0064] The controller 120 may have a memory device. The memory device may include at least one type of storage medium selected from flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card microdisk, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). The memory device may store data and programs required for the operation of the controller 120. The memory device may also store data indicating the results of the operation of the controller 120.

[0065] The controller 120 can collect status information from the information monitoring unit 110 periodically or non-periodically. Based on the status information, the controller 120 can determine the status of multiple battery racks BR1~BR2. m The state of charge (SOC) of each of these is represented. SOC is the ratio of remaining capacity to maximum capacity and is typically expressed in the range of 0 to 100%. Remaining capacity represents the amount of charge currently stored in the battery rack (BR).

[0066] Figure 3 and Figure 4 This describes multiple battery racks BR1~BR m The diagram is for reference when surge current occurs.

[0067] Figure 3 The battery holder BR is shown. i The relationship between open-circuit voltage (OCV) and closed-circuit voltage (CCV) during constant current charging.

[0068] refer to Figure 3 Curve 310 shows the battery rack BR i The relationship between SOC and OCV, i.e., how OCV changes with SOC. Curve 320 shows the relationship between the battery rack BR. iThe relationship between SOC and CCV is shown, that is, the change of OCC with SOC. Curve 330 shows the change of the voltage difference between OCV and CCV with SOC.

[0069] As can be seen from curves 310 and 320, OCV and CCV gradually increase with the increase of SOC.

[0070] Furthermore, the voltage difference between OCV and CCV arises according to Ohm's law, and the voltage difference between OCV and CCV increases as the charging current increases.

[0071] Figure 4 The battery holder BR is shown. i The equivalent circuit model.

[0072] refer to Figure 4 The equivalent circuit model 400 includes a voltage source 410 and an ohmic resistor R. ohm And RC vs. 420.

[0073] Voltage source 410 simulates battery group BG in an electrochemically stable state. i The OCV of the voltage source 410 output is related to the battery group BG. i The SOC has a nonlinear functional relationship ( Figure 3 (Curve 310 in the text).

[0074] Ohm resistor R ohm With battery rack BR i The IR drop V1 is related to the IR drop. IR drop V1 refers to the IR drop in battery pack BG. i Battery grouping (BG) during charging or discharging i The instantaneous voltage change. Ohmic resistance R ohm It reflects the battery rack BR i Internal resistance of each battery cell BC and battery rack BR i The resistance parameters of the physical connectors (e.g., wires or buses) can be determined through pre-testing.

[0075] RC output to 420 is supplied by battery rack BR i Each battery cell BC has an induced overpotential V2 in its double layer and includes a resistor R connected in parallel. P and capacitor C P The overpotential V2 can be referred to as the 'polarization voltage'.

[0076] The time constant of RC with respect to 420 is the resistor R P The resistance value multiplied by the capacitor C P The capacitance result can be preset for each state of charge and each temperature through pre-testing. V ecmThis represents the output voltage of the equivalent circuit model 400, and corresponds to the battery holder BR. i The voltage. V ecm It can be equal to the OCV of the voltage source 410 and the ohmic resistor R. ohm The sum of V1 and RC against V2 of 420.

[0077] When the current I B Upon interruption, V1 immediately becomes 0 [V], while V2 changes gradually. Therefore, in the battery holder BR i After switching from online to offline status, it will take some time for V to work. ecm The voltage difference between V1 and V1 is reduced sufficiently.

[0078] When the battery holder BR i When offline, the battery rack BR i The resistance value can be set to be equal to the ohmic resistance R. ohm When the battery holder BR i When online, the resistance value of the battery holder BRi can be set to equal the ohmic resistance R. ohm With resistor R P sum.

[0079] From the above references Figure 3 and Figure 4 As will be apparent to those skilled in the art from the description, even in multiple battery racks BR1~BR m The SOC of the battery rack in the offline state is equal to that of the battery rack in the online state, and the voltage difference between the two battery racks can also be very large. Furthermore, when multiple battery racks BR1~BR m If two battery racks are offline, but the time difference between each battery rack being offline is large, the voltage difference between the two battery racks may be very large.

[0080] When the battery holder BR i When switching from offline to online, if there is another battery rack that is already online (e.g., BR) m The surge current caused by the voltage difference is greater than that of the switching unit SW. i If the rated current is SW, then the switching unit SW i and battery grouping BG i It may be damaged by overcurrent. In this case, the usable capacity of energy storage system 1 may decrease compared to the battery rack BR. i They all have the same capacity. Therefore, a method is needed to prevent multiple battery racks BR1~BR from being used together. m The risk of surge current in cases where at least two are connected in parallel.

[0081] Figure 5 This is a schematic flowchart illustrating a battery connection control method according to the present disclosure. Figure 5 The method can be derived from Figure 2 The battery connection control device 100 shown is used for this purpose. Figure 5 The method can be used in multiple battery holders BR1~BR m It is executed under the condition that at least one of them is offline and the remaining battery rack is online.

[0082] refer to Figure 5 In step S510, the information monitoring unit 110 monitors multiple battery racks BR1~BR m The status information of each one in it.

[0083] In step S520, the controller 120 determines the offline SOC and online SOC based on the status information. The offline SOC can indicate the SOC of the target battery rack, which is a plurality of battery racks BR1~BR m Any of the battery racks that are currently offline. Online SOC can indicate battery racks BR1~BR m The SOC of at least one battery rack that is in an online state.

[0084] In step S530, the controller 120 determines whether the absolute value of the difference between the offline SOC and the online SOC is less than the threshold SOC. If the value of step S530 is "yes", step S540 can be executed. If the value of step S530 is "no", according to... Figure 5 The method can be completed.

[0085] In step S540, the controller 120 sets a limit on the charging / discharging power of each battery rack in the online state. In an embodiment, setting the charging / discharging power limit may indicate that the controller 120 transmits an operation stop request to the power conversion system 10. Through step S540, the voltage (rack voltage) of each battery rack in the online state may change towards OCV. The elapsed time of the charging / discharging power limit may be counted by the controller 120 in real time until the charging / discharging power limit is removed.

[0086] In step S550, the controller 120 can determine whether the elapsed time for limiting the charging / discharging power is less than a threshold time (e.g., 3 minutes). The threshold time can be preset based on the time constant of RC to 420. When the value of step S550 is "yes", step S560 can be executed. The value of step S550 is "no" corresponding to the case where the time for limiting the charging / discharging power is longer than or equal to the threshold time, and one of the reasons may be that the threshold SOC is too high. When the value of step S550 is "no", step S580 can be executed.

[0087] In step S560, the controller 120 can determine whether the difference between the online voltage and the offline voltage is less than a threshold voltage. The online voltage indicates the voltage of at least one battery rack associated with the online SOC. The offline voltage indicates the voltage of the target battery rack. In step S520, the online voltage and the offline voltage can be determined.

[0088] Consider switching unit SW i Rated current and battery rack BR i The resistance value (e.g., R) ohm The threshold voltage (e.g., 7 [V]) can be preset. For example, in the switching unit SW i The rated current = 200 [A] and R ohm = 0.06 [Ω], when the voltage difference between the online voltage and the offline voltage is equal to or less than 12 [V] (= rated current XR) ohm When the surge current does not exceed the rated current, the surge current should be considered. However, considering the battery rack BR i The threshold voltage can be set to less than 12 [V] to account for the changes in resistance value and the voltage measurement error of the battery pack.

[0089] A value of "Yes" for step S560 corresponds to a situation where the offline voltage is close enough to the online voltage that the risk of inrush current is very low even if the target battery rack switches from offline to online. When the value of step S560 is "Yes", step S570 can be executed. When the value of step S560 is "No", the process can return to step S550.

[0090] In step S570, the controller 120 switches the target battery rack from an offline state to an online state. For example, when the battery rack BR i When the target battery rack is selected, the controller 120 can activate the switching unit SW. i Battery rack BR i You can now log in online.

[0091] When step S570 is executed, the target battery rack can be charged or discharged based on the voltage difference (less than the reference voltage) between at least one battery rack that was already online before step S570 and the target battery rack that newly entered the online state through step S570, thereby achieving safe SOC balance among all battery racks that are online.

[0092] In step S580, the controller 120 updates the threshold SOC by decreasing the threshold SOC by a predetermined value (ΔSOC) (e.g., 0.5%). Step S580 can be a procedure for reducing the number of times the value in step S530 is "yes" and the value in step S560 is "no". After completing step S580, step S582 can be executed.

[0093] In step S582, the controller 120 can determine whether the threshold SOC is less than a predetermined lower SOC limit (e.g., 1%). When the threshold SOC is less than the lower SOC limit, the target battery rack may have almost no chance of switching from offline to online status because the probability of the value of step S530 being "yes" is very low. When the value of step S582 is "yes", step S584 can be executed. When the value of step S582 is "no", step S590 can be executed.

[0094] In step S584, the controller 120 can reset the threshold SOC to a predetermined reference SOC (e.g., 3%). Specifically, the threshold SOC, which has been reduced to below the reference SOC in step S580, can be restored to equal to the reference SOC in step S584. After completing step S584, step S590 can be executed.

[0095] In step S590, the controller 120 removes the limitation on the charging / discharging power of each battery rack that is in the online state. In an embodiment, removing the limitation on the charging / discharging power may mean that the controller 120 transmits a request to restart operation to the power conversion system 10. When step S590 is executed, each battery rack that was temporarily stopped from operating in step S540 and is in the online state can resume charging / discharging.

[0096] Figure 6 This is a schematic illustration of what may be included in Figure 5 The flowchart shows an example of the routine group in step S520. Figure 6 The method can be found in Figure 5 Execute after step S510.

[0097] refer to Figure 6 In step S610, the controller 120, based on the status information, determines the status of the multiple battery racks BR1~BR1. m The SOC of at least one battery rack that is in an online state is determined to determine the online SOC.

[0098] When multiple battery holders BR1~BR m When only one battery rack is online, the controller 120 can determine the SOC of the online battery rack as the online SOC.

[0099] When multiple battery holders BR1~BRm When two or more battery racks are online, the controller 120 can determine the average SOC of the two or more battery racks that are online as the online SOC.

[0100] In step S620, the controller 120 selects multiple battery racks BR1~BR m Any battery rack that is offline is selected as the target battery rack.

[0101] When multiple battery holders BR1~BR m When only one battery rack is offline, the controller 120 can select the offline battery rack as the target battery rack.

[0102] When multiple battery holders BR1~BR m When two or more battery racks are offline, the controller 120 can select any one of the two or more offline battery racks as the target battery rack based on the identification code, SOC, or voltage of each of the two or more offline battery racks.

[0103] As an example, the target battery rack can be the battery rack with the highest priority identification code among two or more battery racks. As another example, the target battery rack can be the battery rack among two or more battery racks where the SOC has the smallest voltage difference with the online SOC. As yet another example, the target battery rack can be the battery rack among two or more battery racks where the voltage has the smallest voltage difference with the online voltage.

[0104] In step S630, the controller 120 determines the SOC of the target battery rack as an offline SOC. After executing step S630, the following can be performed: Figure 5 Step S530.

[0105] Another embodiment of this disclosure may provide a computer-readable storage medium having a program recorded thereon for causing a computer to execute the embodiments described above.

[0106] A program can be implemented using hardware components, software components, and / or a combination thereof. A program can be executed by any system capable of executing computer-readable instructions.

[0107] Software may include computer programs, code, instructions, or combinations thereof, and may be configured to operate or command processing devices independently or jointly as needed.

[0108] Software can be implemented as a computer program comprising instructions stored on a computer-readable storage medium. For example, computer-readable storage media include magnetic recording media (e.g., read-only memory (ROM), random access memory (RAM), floppy disk, hard disk) and optical reader media (e.g., CD-ROM, digital versatile optical disc (DVD)). Computer-readable storage media can be distributed across computer systems connected via a network to allow for distributed storage and execution of computer-readable code. The storage medium can be read by a computer, stored in memory, and executed by a processor.

[0109] Computer-readable storage media can be configured as non-transitory storage media. Here, 'non-transitory storage media' refers to a tangible device and excludes signals (e.g., electromagnetic waves), and the term includes both semi-permanent and temporary data storage on the storage medium. For example, 'non-transitory storage media' may include a buffer where data is temporarily stored.

[0110] Furthermore, the program may include and be incorporated into a computer program product. The computer program product may be a product traded between a seller and a buyer.

[0111] Computer program products may include software programs and computer-readable storage media on which the software programs are stored. For example, a computer program product may include a product in the form of a software program (e.g., a downloadable application) distributed electronically through an electronic device manufacturer or electronic marketplace. For electronic distribution, at least a portion of the software program may be stored on a storage medium or may be temporarily created. In this case, the storage medium may be the storage medium of an electronic device manufacturer's server, an electronic marketplace's server, or an intermediary server temporarily storing the software program.

[0112] Controller 120 may include a processor and memory. When a program stored in memory is executed by the processor, the program causes the processor to perform the following steps: monitoring multiple battery racks BR1~BR m The status information of each of the multiple battery racks BR1~BR m Each of them can be connected in parallel between a pair of power lines; online SOC and offline SOC are determined based on status information, with the online SOC indicating multiple battery racks BR1~BR m The SOC of at least one battery rack that is online, while the offline SOC indicates the SOC of a target battery rack, which is a plurality of battery racks BR1~BR mAny battery rack in the offline state; when the difference between the online SOC and the offline SOC is less than a threshold SOC, set a limit on the charging / discharging power of each battery rack in the online state; when the elapsed time of the limit on the charging / discharging power is less than a threshold time, determine the online voltage indicating the voltage of at least one battery rack in the online state and the offline voltage indicating the voltage of the target battery rack; and when the difference between the online voltage and the offline voltage is less than the threshold voltage, switch the target battery rack from the offline state to the online state.

[0113] The embodiments of the present disclosure described above are not implemented solely by devices and methods, but can be implemented by a program that performs functions corresponding to the exemplary configurations of the present disclosure or by a recording medium on which the program is recorded, and such embodiments can be readily implemented by those skilled in the art based on the disclosure of the previously described embodiments.

[0114] Although this disclosure has been described above with reference to specific embodiments and drawings, it is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes can be made to it within the scope of the various technical aspects of this disclosure and the appended claims and their equivalents.

[0115] Furthermore, since those skilled in the art can make many substitutions, modifications and changes to this disclosure without departing from the various technical aspects of this disclosure, this disclosure is not limited to the above embodiments and drawings, and some or all of the embodiments can be selectively combined to allow for various modifications.

Claims

1. A battery connection control method, comprising: The status information of each of a plurality of battery racks is monitored, each of which can be connected in parallel between a pair of power lines; Based on the state information, the online state of charge (SOC) and offline state of charge (SOC) are determined. The online SOC indicates the SOC of at least one of the plurality of battery racks that is in an online state, while the offline SOC indicates the SOC of a target battery rack, which is any one of the plurality of battery racks that is in an offline state. When the difference between the online SOC and the offline SOC is less than the threshold SOC, a limit is set on the charging / discharging power of each battery rack in the online state; When the elapsed time of the limitation on the charging / discharging power is less than a threshold time, the online voltage and offline voltage are determined, wherein the online voltage indicates the voltage of the at least one battery rack in the online state, and the offline voltage indicates the voltage of the target battery rack; as well as When the difference between the online voltage and the offline voltage is less than a threshold voltage, the target battery rack is switched from the offline state to the online state.

2. The battery connection control method according to claim 1 further includes: When two or more of the plurality of battery racks are in the offline state, any one of the two or more battery racks in the offline state is identified as the target battery rack based on at least one of the identification code, voltage, and SOC of each of the two or more battery racks in the offline state.

3. The battery connection control method according to claim 1, When only one of the plurality of battery racks is in the online state, the online SOC is determined to be equal to the SOC of the only battery rack in the online state, and When two or more of the plurality of battery racks are in the online state, the online SOC is determined to be equal to the average SOC of the two or more battery racks in the online state.

4. The battery connection control method according to claim 1 further includes: After switching the target battery rack from the offline state to the online state, the limitation on the charging / discharging power of each battery rack in the online state is removed.

5. The battery connection control method according to claim 1, further comprising: When the elapsed time of the limitation on the charging / discharging power is equal to or greater than the threshold time, the threshold SOC is reduced by a predetermined value.

6. The battery connection control method according to claim 1, further comprising: When the elapsed time of the limitation on the charging / discharging power is equal to or greater than the threshold time, the limitation on the charging / discharging power of each battery rack in the online state is removed.

7. The battery connection control method according to claim 1, further comprising: When the difference between the online voltage and the offline voltage is less than the threshold voltage, the threshold SOC is reset to a predetermined reference SOC.

8. The battery connection control method according to claim 1, When the difference between the online voltage and the offline voltage is equal to or greater than the threshold voltage, the limitation on the charging / discharging power is maintained.

9. A computer-readable medium having thereon a program for causing a computer to perform the method according to any one of claims 1 to 8.

10. A battery connection control device, comprising: The monitoring unit is configured to monitor the status information of each of a plurality of battery racks, each of which can be connected in parallel between a pair of power lines; as well as Controller The controller is configured to determine the online state of charge (SOC) and offline state of charge (SOC) based on the state information. The online SOC indicates the SOC of at least one battery rack that is in an online state among the plurality of battery racks, while the offline SOC indicates the SOC of a target battery rack, which is any one of the plurality of battery racks that is in an offline state. When the difference between the online SOC and the offline SOC is less than a threshold SOC, the controller sets a limit on the charging / discharging power of each battery rack in the online state; When the elapsed time for limiting the charging / discharging power is less than a threshold time, the controller determines the online voltage and the offline voltage, the online voltage indicating the voltage of the at least one battery rack in the online state, and the offline voltage indicating the voltage of the target battery rack; and When the difference between the online voltage and the offline voltage is less than a threshold voltage, the controller switches the target battery rack from the offline state to the online state.

11. The battery connection control device according to claim 10, wherein, The controller is also configured to: After switching the target battery rack from the offline state to the online state, the limitation on the charging / discharging power of each battery rack in the online state is removed.

12. The battery connection control device according to claim 10, wherein, The controller is also configured to: When the elapsed time of the limitation on the charging / discharging power is equal to or greater than the threshold time, the threshold SOC is reduced by a predetermined value.

13. The battery connection control device according to claim 10, wherein, The controller is also configured to: When the elapsed time of the limitation on the charging / discharging power is equal to or greater than the threshold time, the limitation on the charging / discharging power of each battery rack in the online state is removed.

14. The battery connection control device according to claim 10, wherein, The controller is also configured to: When the difference between the online voltage and the offline voltage is less than the threshold voltage, the threshold SOC is reset to a predetermined reference SOC.

15. An energy storage system comprising a battery connection control device according to any one of claims 10 to 14.

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