Energy storage device having battery pack parallel connection structure

Abstract

The present invention provides an energy storage device having a battery pack parallel connection structure, which is an energy storage device comprising a plurality of battery packs and a battery protection unit for integrally managing the plurality of battery packs. The battery pack includes: a pack case in which a plurality of battery cells are disposed, and a positive electrode terminal and a negative electrode terminal are formed on each of one side and the other side; a positive electrode busbar mounted inside the pack case and electrically connecting the positive electrode terminal on one side and the positive electrode terminal on the other side of the pack case; and a negative electrode busbar mounted inside the pack case and electrically connecting the negative electrode terminal on one side and the negative electrode terminal on the other side of the pack case, wherein in the battery packs adjacent to each other in a horizontal direction, the positive electrode terminals and the negative electrode terminals are respectively connected to each other via separate connection cables for each polarity, thereby forming a single parallel group, and the battery packs forming the parallel group are electrically connected in parallel to the positive electrode busbar and the negative electrode busbar via the connection cables.

Description

Energy storage device having a battery pack parallel connection structure

[0001] The present invention relates to an energy storage device having a battery pack parallel connection structure. More specifically, the invention relates to an energy storage device having a battery pack parallel connection structure that improves operational stability by allowing the entire system to continue operating without stopping even in the event of a specific battery pack failure, simplifies the arrangement structure unlike a series structure, and improves space efficiency by increasing the number of stacked battery packs relative to the same installation area.

[0002] An Energy Storage System (ESS) is a system that stores and discharges large amounts of power by connecting multiple battery packs containing multiple battery cells.

[0003] Generally, ESS is used in conjunction with renewable energy facilities such as solar and wind power to store electricity or to reduce peak demand and improve power quality. Since such ESS operates in high-voltage and high-current environments, a structure is required to efficiently connect multiple battery packs and control them stably.

[0004] A typical ESS consists of multiple battery packs arranged in rack units, each rack containing multiple battery packs, and the battery packs are connected in series to form a rack group.

[0005] FIG. 1 is a conceptual diagram illustrating the battery pack connection structure of a general energy storage device according to the prior art.

[0006] Referring to FIG. 1, a plurality of battery packs (100) are vertically stacked to form a rack group (RG), and the plurality of battery packs (100) forming the rack group (RG) are electrically connected in series to form a total voltage.

[0007] These rack groups (RG) are arranged in multiple numbers along the horizontal direction, and each of the multiple rack groups (RG) is connected to a separate battery protection unit (BPU) (200) and managed collectively by rack group (RG).

[0008] In a typical energy storage device configured in this way, if a specific battery pack or a specific rack group malfunctions, the operation of the entire rack group or the entire system may be restricted due to the nature of the serial connection.

[0009] In particular, in such conventional structures, if a specific battery pack malfunctions and is disconnected or physically removed, the serial connection path is severed, causing the power path for the corresponding rack group or the entire system to be cut off. Consequently, the faulty pack can only be replaced after the entire system is shut down, presenting a limitation where partial isolation and continuous operation during operation are difficult.

[0010] Furthermore, as energy storage facilities have recently become larger and more highly integrated, space efficiency—which allows for storing more energy within the same installation area—is emerging as an important design factor. However, in the structure of conventional technology, space efficiency is reduced because a Battery Protection Unit (BPU) is provided for each rack group, and additional space is required for maintenance due to the serial structure, which further degrades space efficiency.

[0011] The present invention was developed to solve the problems of the prior art. The objective of the present invention is to provide an energy storage device having a battery pack parallel connection structure that can maintain the continuity of the power rail even if a specific battery pack malfunctions and the battery cells of that pack are cut off, by connecting a plurality of battery packs in a parallel structure and providing a bus bar inside each battery pack that constantly electrically connects one terminal and the other terminal.

[0012] Another objective of the present invention is to provide an energy storage device having a battery pack parallel connection structure that improves operational stability by allowing the entire system to continue operating without stopping even in the event of a specific battery pack failure, simplifies the arrangement structure unlike a series structure, and improves space efficiency by increasing the number of stacked battery packs relative to the same installation area.

[0013] The present invention provides an energy storage device comprising a plurality of battery packs and a battery protection unit that manages the plurality of battery packs, wherein the battery pack comprises: a pack case having a plurality of battery cells arranged therein and having a positive terminal and a negative terminal formed on one side and the other side, respectively; a positive busbar mounted inside the pack case and electrically connecting the positive terminal on one side and the positive terminal on the other side of the pack case; and a negative busbar mounted inside the pack case and electrically connecting the negative terminal on one side and the negative terminal on the other side of the pack case, wherein battery packs adjacent to each other in a horizontal direction are interconnected through a separate connecting cable such that the positive terminals and negative terminals of the same polarity form a parallel group, and the battery packs forming the parallel group are electrically connected in parallel through the positive and negative busbars and the connecting cable.

[0014] At this time, the parallel groups are stacked in a vertical direction, and the multiple parallel groups are connected in parallel to each other and can be connected to the battery protection unit.

[0015] In addition, the inside of the pack case is provided with a pack disconnection unit capable of disconnecting the electrical connection between the internal battery cell and the positive and negative busbars, and the pack disconnection unit is controlled to operate when the current or voltage of the battery cell is above a reference value, and even when the pack disconnection unit operates and disconnects the battery cell of the battery pack from the positive and negative busbars, the parallel group can maintain an electrical parallel connection state by the positive and negative busbars of the battery pack.

[0016] Additionally, the pack disconnection unit includes a shunt resistor for measuring the current of the battery cell and a relay for opening and closing the contact between the battery cell and the positive and negative busbars, and when the current measured by the shunt resistor or the voltage measured by the pack battery management unit provided inside the pack case is greater than or equal to a reference value, the relay can be opened to operate so that the battery cell is disconnected from the positive and negative busbars.

[0017] In addition, the pack battery management unit transmits measurement data regarding the voltage and current of the battery cell to the battery protection unit, and the battery protection unit determines whether there is an abnormality in the battery pack based on the measurement data received from the pack battery management unit, and if it is determined that there is an abnormality, it can generate a cutoff operation signal for the pack cutoff unit of the battery pack.

[0018] In addition, the energy storage device having the battery pack parallel connection structure further includes a bypass cable capable of connecting the positive and negative terminals of battery packs adjacent to each other on both sides of a specific battery pack with the same polarity, and when the specific battery pack is physically removed, the parallel group can have the remaining battery packs, excluding the specific battery pack, electrically connected in parallel through the bypass cable.

[0019] According to the present invention, since the continuity of the power rail can be maintained regardless of whether the pack disconnection unit is operating due to the positive and negative busbars provided inside each battery pack, even if a specific battery pack malfunctions, only that pack can be electrically isolated and the remaining battery packs can continue to operate in parallel normally.

[0020] In addition, by excluding a series-connection-based rack group structure and configuring it with a parallel group structure, the risk of voltage interruption at the rack group level can be reduced, the number of battery protection units can be decreased, and the maintenance and insulation spaces can be minimized, thereby improving energy density for the same space.

[0021] In addition, since the power path can be restored via a bypass cable even when a specific battery pack is physically removed, it has the effect of improving maintenance flexibility.

[0022] FIG. 1 is a conceptual diagram illustrating the battery pack connection structure of a general energy storage device according to the prior art.

[0023] FIG. 2 is a conceptual diagram illustrating the battery pack connection structure of an energy storage device according to one embodiment of the present invention.

[0024] FIG. 3 is a conceptual perspective view illustrating a connection structure of mutually adjacent battery packs according to one embodiment of the present invention.

[0025] FIG. 4 is a cross-sectional view conceptually illustrating the connection structure of mutually adjacent battery packs according to one embodiment of the present invention.

[0026] FIG. 5 is a conceptual diagram illustrating a battery pack connection structure through a bypass cable according to one embodiment of the present invention.

[0027] Hereinafter, specific embodiments for implementing the present invention will be described in detail with reference to the drawings.

[0028] First, it should be noted that when assigning reference numerals to the components of each drawing, the same components are assigned the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, if it is determined that a detailed description of related known components or functions could obscure the essence of the invention, such detailed description is omitted.

[0029] Furthermore, when it is stated that one component is 'connected,' 'supported,' 'connected,' 'supplied,' 'transmitted,' or 'contacted' with another component, it should be understood that while the connection, support, connection, supply, transmission, or contact may be direct to that other component, there may also be other components present in between.

[0030] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] Furthermore, it should be noted in advance that expressions such as "upper side," "lower side," and "side" in this specification are described based on the drawings, and may be expressed differently if the orientation of the object changes. For the same reason, some components in the attached drawings may be exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0032] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but such components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0033] The meaning of "comprising" as used in the specification is to specify certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0034] FIG. 2 is a conceptual diagram illustrating a battery pack connection structure of an energy storage device according to an embodiment of the present invention, FIG. 3 is a conceptual perspective view illustrating a connection structure of mutually adjacent battery packs according to an embodiment of the present invention, FIG. 4 is a conceptual cross-sectional view illustrating a connection structure of mutually adjacent battery packs according to an embodiment of the present invention, and FIG. 5 is a conceptual diagram illustrating a battery pack connection structure through a bypass cable according to an embodiment of the present invention.

[0035] An energy storage device according to the present invention may be configured to include a plurality of battery packs (100) and a battery protection unit (BPU) (200) that manages the plurality of battery packs (100).

[0036] Each battery pack (100) may include a pack case (120) in which a plurality of battery cells (110) are accommodated inside, and a plurality of positive terminals (121) and negative terminals (122) may be formed on one side and the other side of the pack case (120), respectively. The positive terminals (121) and negative terminals (122) may be connected to an external connection cable (150) to be electrically connected to an adjacent battery pack (100).

[0037] A positive busbar (130) and a negative busbar (140) may each be provided inside the pack case (120). The positive busbar (130) may be arranged to directly electrically connect one positive terminal (121) and the other positive terminal (121) of the pack case (120), and the negative busbar (140) may be arranged to directly electrically connect one negative terminal (122) and the other negative terminal (122) of the pack case (120). Accordingly, the positive busbar (130) and the negative busbar (140) may be configured to form a pass-through power path penetrating one side and the other side inside the battery pack (100).

[0038] A plurality of battery packs (100) may be arranged adjacently in a horizontal direction, and the positive terminal (121) of each battery pack (100) and the positive terminal (121) of an adjacent battery pack (100) may be connected to each other through a connecting cable (150), and the negative terminals (122) may also be connected to each other with the same polarity to form a parallel group (PG).

[0039] In a parallel group (PG), the positive busbar (130) and negative busbar (140) provided inside each battery pack (100) form a common positive rail and negative rail, respectively, and the connecting cable (150) can operate to form a parallel power grid by continuously connecting the same potential point between adjacent packs. In such a structure, since all battery packs (100) share and supply current while maintaining the same voltage level, the total current supply capacity of the parallel group (PG) can be increased in proportion to the current capacity of the individual packs.

[0040] A battery pack (100) can be configured by separating the connection relationship between a positive busbar (130) and a negative busbar (140) that form a power rail of a parallel group (PG) and a battery cell (110) that supplies power to the power rail. Specifically, the positive busbar (130) and the negative busbar (140) can be formed as a pass-through power path that connects a positive terminal (121) and a negative terminal (122) formed on one side of a pack case (120) and a positive terminal (121) and a negative terminal (122) formed on the other side, respectively. Accordingly, the positive busbar (130) can form a positive rail that directly conducts the positive terminal (121) on one side and the positive terminal (121) on the other side, and the negative busbar (140) can form a negative rail that directly conducts the negative terminal (122) on one side and the negative terminal (122) on the other side.

[0041] The battery cell (110) may be configured not to be always fixedly connected to the positive busbar (130) and the negative busbar (140), but to be selectively connected through a pack blocking unit (170) placed between them. That is, the opening and closing elements of the pack blocking unit (170) may be configured to intervene between the positive side output of the battery cell (110) and the positive busbar (130), and between the negative side output of the battery cell (110) and the negative busbar (140), thereby allowing the battery cell (110) to be controlled to be electrically connected to or disconnected from the power rail (busbar).

[0042] The pack blocking unit (170) may include a relay that opens and closes the electrical connection between the battery cell (110) and the busbars (130, 140). The relay may maintain the contacts in a closed state during normal operation so that the output power of the battery cell (110) is applied to the positive busbar (130) and the negative busbar (140). At this time, the current output from the battery cell (110) may be transmitted to the busbars (130, 140) via the relay contacts, and the busbars (130, 140) may be operated to form a common power rail of a parallel group (PG) by being connected in parallel with adjacent battery packs (100) via a connecting cable (150). As a result, during normal operation, each battery pack (100) functions as a power source connected in parallel to a common rail of the same voltage level, thereby distributing and supplying the current of the entire parallel group (PG).

[0043] The pack cutoff unit (170) may include a shunt resistor for measuring the output current of the battery cell (110). The shunt resistor may be placed on the current path between the battery cell (110) and the busbar (130, 140) and configured to detect the magnitude of the current through the voltage drop that occurs when power is applied. In addition, a Pack Battery Management System (PBMS) (not shown) may be provided inside the pack case (120), and the Pack Battery Management System (PBMS) may be configured to sense the voltage of the battery cell (110) and collect current data from the shunt resistor to monitor the operating status of the battery pack (100) in real time.

[0044] The pack disconnection unit (170) operates to open a relay so that the battery cell (110) is disconnected from the positive and negative busbars (130, 140) when the current measured by the shunt resistor or the voltage measured by the pack battery management unit (PBMS) is above a reference value.

[0045] At this time, the pack battery management unit transmits measurement data regarding the voltage and current of the battery cell to the battery protection unit (200), and the battery protection unit (200) determines whether there is an abnormality in the battery pack (100) based on the measurement data received from the pack battery management unit, and if it is determined that there is an abnormality, it can generate a cutoff operation signal for the pack cutoff unit (170) of the battery pack (100).

[0046] The battery protection unit (200) can determine whether the voltage and current of the transmitted battery cell exceed a set reference range and can detect abnormal conditions such as, for example, overcurrent, overvoltage, undervoltage, overtemperature (if a temperature sensor is included) or suspected internal short circuit conditions.

[0047] When an abnormal condition is detected, the battery protection unit (200) can control the relay of the pack disconnection unit (170) to open. When the relay is opened, the electrical connection between the battery cell (110) and the busbar (130, 140) is cut off, and the battery pack (100) can stop functioning as a power source for the parallel group (PG). At this time, since the battery cell (110) is electrically disconnected from the busbar (130, 140), safety can be ensured by suppressing the inflow of reverse current from the abnormal pack or the continuous flow of abnormal current.

[0048] Meanwhile, in the present invention, the positive busbar (130) and the negative busbar (140) are formed as a pass-through power path that keeps one terminal and the other terminal constantly conductive regardless of the opening and closing operation of the pack blocking unit (170). Therefore, even if the battery cell (110) of a specific battery pack (100) is blocked, the power rail of the parallel group (PG) itself is not disconnected. That is, the battery pack (100) does not participate in power supply, but can remain as a pass-through path that provides rail continuity between the positive terminal (121) and the negative terminal (122). Accordingly, the same polarity rail can be continuously maintained between adjacent battery packs (100) through the connecting cable (150) and the busbars (130, 140) of each pack, and other battery packs (100) can continue parallel operation without being affected.

[0049] Consequently, the battery pack (100) according to the present invention can be implemented so that, in the event of an abnormal battery pack, the power source can be rapidly isolated while maintaining the power rail continuity of the parallel group (PG) by functionally separating the continuous path of the power rail (busbar) and the battery cell (power source) through the pack disconnection unit (170).

[0050] Meanwhile, multiple parallel groups (PGs) may be stacked in a vertical direction. Each parallel group (PG) may be configured to form a structurally independent parallel power block, and each parallel group (PG) may be configured to be connected in parallel to a single battery protection unit (BPU) (200). That is, multiple parallel groups (PGs) may be connected to the battery protection unit (200) by having their respective positive and negative output terminals connected in parallel to a common power line while sharing the same voltage level.

[0051] In this configuration, each parallel group (PG) can operate to maintain the same voltage while supplying current independently, and the battery protection unit (200) can be configured to collect voltage and current information transmitted from each parallel group (PG) and perform integrated control. Therefore, even if some battery packs (100) included in a specific parallel group (PG) are cut off, the remaining battery packs (100) within that parallel group (PG) can supply current normally while maintaining the continuity of the power rail, and the operation of other parallel groups (PG) can be minimized.

[0052] In addition, if each battery pack (100) is configured to include its own high-voltage battery stack, no additional series voltage stack configuration is required between parallel groups (PG), and all parallel groups (PG) can operate in a structure where only the current capacity is expanded while maintaining the same target voltage. Accordingly, the entire system forms a parallel expandable power structure and can be designed to enable high output and large capacity configurations without series stack connections that entail a risk of voltage disconnection.

[0053] A parallel expandable power structure like the present invention can also be advantageously implemented in terms of space efficiency. In conventional series stack structures, since each battery pack is placed at a different potential, it may be essential to secure insulation distances between packs, arrange insulation members according to potential differences, and secure spacing to prevent exposure to high voltage. Accordingly, when vertically stacking, sufficient insulation spacing must be maintained between each pack, and as a result, the stacking density may be limited relative to the same installation area.

[0054] On the other hand, in the present invention, each battery pack (100) is configured to form a target voltage on its own, and all battery packs (100) within a parallel group (PG) can be configured to share the same voltage level. Therefore, it can be designed so that no significant potential difference occurs between each battery pack connected in horizontal parallel, and arrangement can be made under the same voltage conditions between parallel groups (PG) that are stacked vertically. Accordingly, the step-by-step insulation partitions required in a series stack structure may be unnecessary or minimized.

[0055] Furthermore, since the present invention is configured to disconnect only the battery cells of a specific battery pack when an abnormality occurs in that pack while maintaining the continuity of the power rail, the need to secure extra space in the overall structure for fault response can be reduced. In contrast to conventional structures where maintenance or isolation space had to be secured to prepare for serial path disconnection, the present invention maintains power continuity at the parallel group (PG) level, allowing for a more intensive design of the maintenance space.

[0056] Furthermore, by adopting a structure in which each parallel group (PG) is connected in parallel to a single battery protection unit (200), the need to arrange multiple control devices for each group as in the conventional method can be reduced. Accordingly, the space for arranging control units, wiring, and designing cooling paths can be reduced, and a highly integrated design can be configured to allow for stacking more battery packs in the same volume.

[0057] In particular, as the positive busbar (130) and negative busbar (140) of each battery pack (100) are formed in a pass-through structure to continuously form power rails between adjacent packs, a separate large external power rail or additional current collection structure can be minimized. Accordingly, the wiring path inside the rack is simplified, the power transfer structure can be modularized, and consequently, it can be designed to enable a structurally dense layout.

[0058] Accordingly, the present invention can realize a space-efficient structure that can increase the number of stacked battery packs and improve energy density relative to the same installation area by easing the requirements for stepwise insulation design and maintenance space required in a series stack structure, and by configuring it to expand current capacity while maintaining the same voltage level through a parallel-based power structure.

[0059] Referring to FIG. 5, when a specific battery pack (100) is physically removed, a bypass cable (160) may be additionally connected to connect the corresponding positive terminal (121) and negative terminal (122) of an adjacent battery pack (100). The bypass cable (160) may function to restore the power rail of a parallel group (PG) by replacing the removed battery pack (100). Accordingly, the power path can be quickly restored even during maintenance.

[0060] When examining the power flow process in the battery pack parallel connection structure of the present invention configured as described above, this power flow process can be explained by dividing it into three stages: a normal operating state, a cutoff state of a specific battery pack, and a physical removal state of a specific battery pack.

[0061] In a normal operating state, the battery cells (110) of each battery pack (100) may be configured to remain electrically connected to the positive busbar (130) and the negative busbar (140) through the pack disconnection unit (170). At this time, the current output from the battery cells (110) may be applied to the positive busbar (130) and the negative busbar (140) by passing through the relay contacts of the pack disconnection unit (170).

[0062] The positive busbar (130) can be configured to electrically connect one positive terminal (121) and the other positive terminal (121) of the pack case (120) to form a continuous positive power rail, and the negative busbar (140) can also be configured to connect one negative terminal (122) and the other negative terminal (122) to form a continuous negative power rail.

[0063] Since adjacent battery packs (100) are connected in parallel with terminals of the same polarity through a connecting cable (150), the positive busbar (130) of each battery pack can operate to form a common positive rail of the parallel group (PG), and the negative busbar (140) of each battery pack can operate to form a common negative rail of the parallel group (PG). Accordingly, each battery pack can form a parallel operation state in which it shares and supplies current while maintaining the same voltage.

[0064] In this state, the parallel group (PG) can be connected to the battery protection unit (200) and controlled integrally, and the pack battery management unit (PBMS) of each pack can be configured to monitor voltage and current status in real time.

[0065] Next, the cutoff state of a specific battery pack is achieved by the PBMS inside the pack opening the relay of the pack cutoff unit (170) when an overvoltage, overcurrent, or abnormal condition is detected in the battery cell (110) of the specific battery pack (100). Accordingly, the battery cell (110) is electrically disconnected from the positive busbar (130) and the negative busbar (140).

[0066] At this time, the positive busbar (130) and the negative busbar (140) are configured to always connect one terminal and the other terminal regardless of whether the pack blocking unit (170) is open. Therefore, the internal battery cell (110) of the battery pack (100) is excluded from the power rail, but the power path formed by the positive busbar (130) and the negative busbar (140) is not disconnected.

[0067] That is, the blocked battery pack (100) does not participate in power supply, but can function as a power passage path that physically connects the positive and negative rails of the parallel group (PG). Accordingly, the remaining battery packs (100) can supply current normally while maintaining the continuity of the power rails.

[0068] Consequently, the disconnection of a specific battery pack does not interrupt the entire power path of the parallel group (PG), and the operation of the entire system can continue.

[0069] Next, the physical removal state of a specific battery pack is the state in which the blocked battery pack (100) is physically removed from the rack. In this case, the electrical connection path between one terminal and the other terminal, which was maintained by the positive busbar (130) and the negative busbar (140) formed on the battery pack (100), is physically eliminated.

[0070] In this case, the corresponding positive terminal (121) and negative terminal (122) of the battery pack (100) adjacent to both sides of the removed battery pack (100) are no longer directly connected, so the power rail of the parallel group (PG) can be disconnected.

[0071] To prevent this, the present invention may be configured to include a bypass cable (160). The bypass cable (160) may be configured to directly connect the terminals of the same polarity of the battery packs (100) adjacent to both sides of the removed battery pack (100). Accordingly, a new power path bypassing the removed battery pack (100) is formed, thereby restoring the power rail of the parallel group (PG).

[0072] According to this structure, the present invention can simultaneously ensure operational continuity and maintenance flexibility by allowing all battery packs to participate in power supply in parallel during normal operation, interrupting power supply to only specific battery packs and maintaining the power rail during cutoff, and reconfiguring the power rail through a bypass cable during physical removal.

[0073] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

1. An energy storage device comprising a plurality of battery packs and a battery protection unit that manages the plurality of battery packs in an integrated manner, The above battery pack is A pack case having multiple battery cells arranged inside, with a positive terminal and a negative terminal formed on one side and the other side, respectively; A positive busbar mounted inside the above-mentioned pack case and electrically connecting one positive terminal and the other positive terminal of the above-mentioned pack case; and It includes a negative busbar mounted inside the above-mentioned pack case and electrically connecting one negative terminal and the other negative terminal of the above-mentioned pack case, An energy storage device having a battery pack parallel connection structure, wherein battery packs adjacent to each other in a horizontal direction are interconnected through separate connecting cables such that the positive and negative terminals of the same polarity form a parallel group, and the battery packs forming the parallel group are electrically connected in parallel through the positive and negative busbars and the connecting cables.

2. In Paragraph 1, The above parallel groups are stacked in multiple directions in the vertical direction, and An energy storage device having a battery pack parallel connection structure, wherein a plurality of the above parallel groups are connected in parallel to each other and connected to the battery protection unit.

3. In Paragraph 1, Inside the above pack case, a pack cutoff unit capable of interrupting the electrical connection between the internal battery cell and the positive and negative busbars is provided, and the pack cutoff unit is controlled to operate when the current or voltage of the battery cell is above a reference value. An energy storage device having a battery pack parallel connection structure, wherein even when the above-mentioned pack disconnection unit operates and the battery cells of the battery pack are disconnected from the positive and negative busbars, the parallel group maintains an electrically parallel connection state by the positive and negative busbars of the battery pack.

4. In Paragraph 3, The above pack blocking unit is It includes a shunt resistor for measuring the current of the battery cell and a relay for opening and closing contacts between the battery cell and the positive and negative busbars. An energy storage device having a battery pack parallel connection structure that operates to open the relay so that the battery cell is separated from the positive and negative busbars when the current measured by the shunt resistor or the voltage measured by the pack battery management unit provided inside the pack case is greater than or equal to a reference value.

5. In Paragraph 4, The above-mentioned pack battery management unit transmits measurement data regarding the voltage and current of the battery cell to the battery protection unit, and An energy storage device having a battery pack parallel connection structure, wherein the battery protection unit determines whether there is an abnormality in the battery pack based on measurement data received from the pack battery management unit, and if it is determined that there is an abnormality, generates a cutoff operation signal for the pack cutoff unit of the battery pack.

6. In Paragraph 3, It further includes a bypass cable capable of connecting the positive and negative terminals of battery packs, each positioned adjacently on both sides of a specific battery pack, to each other with the same polarity. An energy storage device having a battery pack parallel connection structure, wherein when a specific battery pack is physically removed, the parallel group is electrically connected in parallel to the remaining battery packs excluding the specific battery pack through the bypass cable.

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