Battery rack and battery rack management method

Abstract

The present invention relates to a battery rack for improving cell balancing speed of newly replaced battery packs in an ESS rack system and a cell balancing method for a battery pack included in the battery rack. The battery rack according to an embodiment of the present invention includes a plurality of battery packs each including an electrochemical impedance spectroscopy (EIS) measurement unit, a state of charge (SOC) monitoring unit that monitors an SOC of each battery pack, and a rack control unit that controls the EIS measurement unit of a selected first battery pack among the plurality of battery packs to perform an EIS measurement when the SOC of the first battery pack differs from an average SOC value of the other battery packs or the SOC of any other battery pack by a predetermined reference value or more.

Description

Technical Field

[0001] This invention relates to energy storage system (ESS) rack systems, and more specifically, to a battery rack for balancing newly replaced battery packs in an ESS rack system, and a method for managing the battery rack to balance the battery packs constituting the rack. Background Technology

[0002] Currently commercially available rechargeable batteries include nickel-cadmium (NiCd), nickel-metal hydride (NiMH), nickel-zinc (NiZn), and lithium-ion batteries. Among these, lithium-ion batteries have attracted attention due to their advantages, such as allowing flexible charge and discharge operations, exhibiting a very low self-discharge rate, and providing high energy density due to the absence of memory effect compared to nickel-based batteries.

[0003] These lithium-ion rechargeable batteries primarily use lithium oxide and carbon materials as the positive and negative electrode active materials, respectively. A lithium-ion rechargeable battery comprises an electrode assembly and external materials. The electrode assembly includes a positive electrode plate and a negative electrode plate, each coated with a positive electrode active material and a negative electrode active material, respectively. A separator is inserted between the positive and negative electrode plates. The external materials, i.e., the battery bag's external materials, hermetically house the electrode assembly together with the electrolyte.

[0004] In recent years, secondary batteries have been widely used not only in small devices such as portable electronic devices, but also in medium and large devices such as vehicles and power storage devices. When used in these medium and large devices, a large number of secondary batteries are electrically connected to increase capacity and output. Specifically, pouch-type secondary batteries are widely used in these medium and large devices due to their ease of stacking.

[0005] Meanwhile, with the recent increasing demand for high-capacity structures (including applications as energy storage sources), there is a growing demand for battery racks equipped with multiple secondary batteries connected in series and / or parallel, as well as battery modules and battery management systems (BMS) that house the secondary batteries.

[0006] An Energy Storage System (ESS) rack system comprises multiple battery packs. Furthermore, when a battery pack in an ESS rack system has a problem, instead of repairing the entire rack, only the defective battery pack is replaced with a new one.

[0007] In this situation, the newly replaced battery pack may have a low state of health (SOH) compared to the existing battery pack. That is, because the existing battery pack has not undergone SOH degradation, its state of charge (SOC) may not be balanced with the newly replaced battery pack. Therefore, to achieve SOC balance, cell balancing operations are required to reduce the charge of the newly replaced battery pack through discharge.

[0008] In the prior art, cell balancing operation utilizes a cell balancing element including a balancing resistor and a balancing switch. By connecting the balancing resistor to each cell in the battery pack, a full cell balancing operation is performed on each cell to release battery energy, thereby achieving SOC balance with the existing battery pack.

[0009] However, existing cell balancing operations suffer from a relatively slow balancing speed because the cell balancing current is measured in mA. Specifically, the following problem exists: the battery energy released during cell balancing is simply dissipated as heat through the balancing resistor.

[0010] Relevant technical documents include Korean Patent Publication No. 10-2024-0001366 (published on January 3, 2024) (Patent Document 1) and Korean Patent Publication No. 10-2022-0075024 (published on June 7, 2022) (Patent Document 2). Summary of the Invention

[0011] Technical issues

[0012] This invention provides a battery rack and a battery rack management method for improving the balancing speed of newly replaced battery packs in an ESS rack system.

[0013] This invention provides a battery rack and a battery rack management method that can perform battery pack discharge required for balancing the battery pack, while the battery pack discharge occurs during EIS measurements of the battery pack.

[0014] Technical solution

[0015] According to an embodiment of the present invention, a battery rack includes: a plurality of battery packs, each battery pack including an electrochemical impedance spectroscopy (EIS) measurement unit; a state of charge (SOC) monitoring unit configured to monitor the SOC of each battery pack; and a rack control unit configured to control the EIS measurement unit of the first battery pack to perform an EIS measurement operation when the SOC of a first battery pack selected from the plurality of battery packs differs from the average SOC value of the other battery packs or the SOC of any other battery pack by a predetermined reference value or greater.

[0016] Each battery pack may further include: a battery module comprising one or more battery cells; a cell balancing unit connected to the positive (+) terminal and negative (-) terminal of each of the battery cells constituting the battery module to form a cell balancing path, through which a cell balancing current flows, and the cell balancing unit is configured to selectively discharge each cell; and a battery pack control unit configured to control the operation of the cell balancing unit and the EIS measurement unit in the battery pack under the control of a rack control unit.

[0017] The rack control unit can be configured to control the EIS measurement unit of the first battery pack to perform EIS measurement operation when the SOC of the first battery pack differs from the average SOC of all other battery packs or the SOC of any other battery pack by a predetermined reference value or greater, and to stop the EIS measurement operation of the EIS measurement unit of the first battery pack when the difference between the SOC of the first battery pack and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below the predetermined reference value, and to perform control so that the cells of the first battery pack are balanced with the cells of other battery packs through the cell balancing unit of the first battery pack.

[0018] The cell balancing unit may include: a balancing resistor formed on the cell balancing path, through which cell current flows via a connection between the positive (+) terminal and the negative (-) terminal of each cell, and the balancing resistor is configured to generate a cell potential difference due to the flow of cell current in the cell balancing path; and a balancing switch (B_SW) formed on the cell balancing path and configured to perform cell balancing operation by switching the cell balancing path on / off, and the balancing switch (B_SW) can be controlled to be switched on / off by a control signal from the rack control unit.

[0019] The EIS measurement unit may include an EIS measurement resistor and an EIS current switch (EIS_SW). The EIS measurement resistor forms an EIS measurement path through which an EIS current (AC current for EIS measurement) flows via a connection between the positive (+) terminal and the negative (-) terminal of a battery module 110 comprising one or more battery cells. The EIS measurement resistor is configured to generate an EIS potential difference due to the EIS current flowing in the EIS measurement path. The EIS current switch (EIS_SW) is formed on the EIS measurement path and is configured to discharge the battery module 110 during EIS measurement operations by switching the EIS measurement path on and off at predetermined intervals. The EIS current switch (EIS_SW) can be selectively controlled to be on or off via a control signal from a rack control unit.

[0020] The rack control unit can perform control to selectively operate either the cell balancing unit or the EIS measurement unit when battery pack balancing is required.

[0021] The rack control unit can be a device for controlling the on / off state of the balance switch (B_SW) of the cell balancing unit 120 and the EIS switch (EIS_SW) of the EIS measurement unit 130 based on control signals transmitted from the microcontroller unit (MCU) or battery monitoring IC (BMIC) of the battery management system (BMS). Alternatively, the MCU / BMIC can be configured as a rack control unit, or it can be a device located outside the BMS for controlling the on / off state of the balance switch (B_SW) and the EIS switch (EIS_SW).

[0022] According to an embodiment of the present invention, a method for balancing multiple battery packs constituting a battery rack includes: a SOC monitoring step, wherein the SOC of each battery pack is monitored in a SOC monitoring unit; an EIS measurement step, wherein when, as a result of monitoring, the difference between the SOC of a first battery pack selected from the plurality of battery packs and the average SOC of all other battery packs or the SOC of any other battery pack is equal to or greater than a predetermined reference value, control is executed in a rack control unit to perform an EIS measurement operation in the first battery pack; and a cell balancing step, wherein, as a result of monitoring, the difference between the SOC of the first battery pack and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below a predetermined reference value, the EIS measurement operation of the first battery pack is stopped in the rack control unit, and control is executed to balance the cells of the first battery pack with those of the other battery packs via discharge through a cell balancing unit.

[0023] In the cell balancing step, balancing with any cell of any other battery pack can be performed by discharging each cell of the first battery pack via the cell balancing unit of the first battery pack.

[0024] In the EIS measurement step, an AC current for EIS measurement can be extracted from the first battery pack to measure the EIS of the first battery pack and to discharge the first battery pack.

[0025] In the cell balancing step, each cell set for each cell balancing path is discharged. Each cell balancing path is formed by connecting the positive (+) terminal and the negative (-) terminal of each cell constituting the battery module included in the first battery pack, and cell current flows through each cell balancing path.

[0026] In the EIS measurement step, when the SOC of the first battery pack differs from the SOC of other battery packs by a predetermined reference value or greater, the cell balancing operation through the cell balancing unit may not be performed, and only the EIS measurement may be performed. In the cell balancing step, when the difference between the SOC of the first battery pack and the SOC of other battery packs drops to or below the predetermined reference value, the EIS measurement operation may be stopped and control may be executed to perform the cell balancing operation through the cell balancing unit.

[0027] Beneficial effects

[0028] According to embodiments of the present invention, the balancing speed of newly replaced battery packs in an electrochemical impedance spectroscopy (ESS) rack system can be increased, thereby compensating for economic losses that occur during the balancing process of the battery packs.

[0029] Furthermore, the present invention can utilize the discharge of the battery pack that occurs during the EIS measurement of the battery pack to discharge the battery pack required for balancing the battery pack, thereby allowing the discharge energy of the battery pack (which would be wasted during cell balancing in related technologies) to be used to extract EIS measurement data, which has the effect of improving energy efficiency. Attached Figure Description

[0030] The features and advantages of the invention will be better understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 This is a diagram illustrating the configuration of a battery holder according to an embodiment of the present invention.

[0031] Figure 2 It is shown in detail Figure 1 A diagram showing the configuration of the battery pack.

[0032] Figure 3 This is a diagram illustrating a method for managing a battery rack according to an embodiment of the present invention. Detailed Implementation

[0033] In the following, exemplary embodiments of the invention will be described in detail with reference to the accompanying drawings. However, the invention is not limited to the embodiments disclosed below, but will be implemented in various different forms. Embodiments of the invention are provided only to make this disclosure complete and to fully inform those skilled in the art of the scope of the invention. Here, the drawings may be enlarged to describe the invention in detail, and the same reference numerals refer to the same elements in the drawings.

[0034] Figure 1 This is a diagram illustrating the configuration of a battery holder according to an embodiment of the present invention. Figure 2 It is shown in detail Figure 1 A diagram showing the configuration of the battery pack.

[0035] Reference Figure 1According to an embodiment of the present invention, a battery rack includes a plurality of battery packs 100, each battery pack including a plurality of battery modules 110 (111, 112, and 113), each battery module including one or more battery cells and including an electrochemical impedance spectroscopy (EIS) measurement unit 131 for EIS measurement, a SOC monitoring unit 200 for monitoring the state of charge (SOC) of each battery pack 100, and a rack control unit 300. The rack control unit 300 is used to control the EIS measurement unit 131 of the first battery pack 100 to perform an EIS measurement operation when the SOC of the first battery pack 100 selected from the plurality of battery packs 100 differs from the SOC of the other battery packs by a predetermined reference value or greater. Furthermore, the battery rack 300 also includes a charge / discharge switch or relay 10, which is opened and closed to establish or disconnect a connection with an external device 400 such as a charger or load.

[0036] In this configuration, the external device 400 may include a load such as an inverter or converter, and a charging device. When the external device 400 is a charger, the two ends of the battery holder can be connected to the charger and charged by receiving power from the charger. When the external device 400 is a load, the two ends of the battery holder are connected to the load, allowing the power supplied by the battery holder to discharge through the load.

[0037] Furthermore, one end of the switch or relay 10 is connected to the battery holder, and the other end of the switch or relay 10 is connected to at least one component of the external device 400. The closing and opening of the switch or relay 10 can be controlled according to the relay control signal provided from the battery management system (BMS).

[0038] The battery pack 100 includes: a battery module 111 comprising one or more battery cells; a cell balancing unit 121 connected to the positive (+) terminal and negative (-) terminal of each battery cell constituting the battery module 111 to form a cell balancing path through which a cell balancing current flows, and the cell balancing unit 121 is configured to discharge each cell; an EIS measurement unit 131 connected to the positive (+) terminal and negative (-) terminal of the battery module 111 to form an EIS measurement path through which an EIS current flows, and the EIS measurement unit 131 is configured to discharge the battery module 111 through an EIS measurement operation; and a battery pack control unit 140 configured to control the operation of the cell balancing unit 121 and the EIS measurement unit 131 in the battery pack 100 under the control of the rack control unit 300.

[0039] In this case, Figure 1In this embodiment, multiple battery modules 111 are shown as including cells connected in series, but this embodiment is not limited to this, and the battery cells may be connected in parallel or in a combination of series and parallel connections. Furthermore, a battery pack control unit 140 is included in each battery pack.

[0040] When the SOC of the first battery pack 100 differs from the average SOC of all other battery packs monitored by the SOC monitoring unit 200 or the SOC of any other battery pack by a predetermined reference value or greater, the rack control unit 300 controls the EIS measurement unit 130 of the first battery pack 100 to perform an EIS measurement operation through the battery pack control unit 140.

[0041] In this scenario, the first battery pack 100 may be a new battery pack that has already replaced a problematic battery pack among multiple battery packs included in the battery rack, replacing those that had malfunctioned or otherwise failed. For example, the newly replaced battery pack may exhibit less SOH degradation, while the currently used (unreplaced) existing, healthy battery pack may exhibit SOH degradation. Therefore, the SOC balance between the newly replaced battery pack and the unreplaced battery pack may be mismatched.

[0042] Reference Figure 2 The cell balancing unit 120 of the battery pack 100 includes a balancing resistor 121a formed on the cell balancing path and a balancing switch B_SW formed on the cell balancing path. Cell current flows through the balancing resistor 121a by connecting the positive (+) terminal and the negative (-) terminal of each cell. The balancing resistor 121a is configured to generate a cell potential difference due to the flow of cell current in the cell balancing path. The balancing switch B_SW performs battery pack balancing operations by switching the cell balancing path on / off. In this case, the balancing switch B_SW is selectively switched on / off by a control signal from the rack control unit 300.

[0043] Furthermore, the EIS measurement unit 130 of the battery pack 100 includes: an EIS measurement resistor 131a forming an EIS measurement path through which an EIS current (AC current for EIS measurement) flows via a connection between the positive (+) terminal and the negative (-) terminal of a battery module 110 comprising one or more battery cells, and the EIS measurement resistor 131a is configured to generate an EIS potential difference due to the EIS current flowing in the EIS measurement path; and an EIS current switch EIS_SW formed on the EIS measurement path and configured to discharge a large amount of charge from the battery module 110 during EIS measurement operations by switching the EIS measurement path on and off at predetermined intervals. In this case, the EIS current switch EIS_SW is selectively switched on / off via a control signal from the rack control unit 300 via the battery pack control unit 140.

[0044] Cell balancing unit 120 and EIS measurement unit 130 may be included in BMS. Cell balancing unit 121 and EIS measurement unit 131 are components capable of reducing the charge of at least one battery pack 100 among a plurality of battery packs disposed in an ESS rack, wherein the SOC of the at least one battery pack 100 is not balanced with the SOC of any other battery pack (battery pack balancing operation).

[0045] When a battery pack balancing operation is required (e.g., when the SOC of the first battery module 111 differs from the average SOC of all other battery modules 110 monitored by the SOC monitoring unit 200 or the SOC of any other battery module by a predetermined reference value or greater or less), the rack control unit 300 selectively controls one of the cell balancing unit 120 and the EIS measurement unit 130 to perform the battery pack balancing operation.

[0046] When the SOC monitoring unit 200 indicates that the SOC of the first battery pack 100 differs from the average SOC of all other battery packs or the SOC of any other battery pack by a predetermined reference value or greater, the rack control unit 300 executes control such that the cell balancing unit 121 of the first battery pack 100 does not operate, and only the EIS measurement unit 131 of the first battery pack 100 operates first (EIS measurement operation). That is, AC current for EIS measurement is extracted from the first battery pack 100 that requires battery pack balancing to measure the EIS of the first battery pack 100 while simultaneously discharging the first battery pack 100. In this case, since the EIS measurement operation is performed in A (amperes), the cell balancing performed by the cell balancing unit 120 is achieved at a significantly faster balancing speed than cell balancing performed in mA.

[0047] As a result of the SOC monitoring unit, when the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below a predetermined reference value through EIS measurement, the rack control unit 300 stops the EIS measurement operation of the EIS measurement unit 131 of the first battery pack 100 and executes control so that the battery cells of the first battery pack 100 are balanced with the cells of other battery packs through the cell balancing unit 120 of the first battery pack 100. That is, each cell set on each cell balancing path through which the cell current flows is discharged, and each cell balancing path is formed by connecting the positive (+) terminal and the negative (-) terminal of each battery cell in the battery cell constituting the battery module 111 included in the first battery pack 100 that requires battery pack balancing. In this case, since the battery balancing current is in mA, the battery balancing operation through the cell balancing unit 120 is slow in terms of balancing speed, but accurate cell balancing is possible.

[0048] Meanwhile, the rack control unit 300 is configured to operate as the master BMS, and the battery pack control unit 140 is configured to operate as the slave BMS, thereby achieving effective management and data integration through the measurement and control of the battery system.

[0049] In this way, the rack control unit 300 is the upper-level control device that manages the entire battery rack system. In this manner, the rack control unit 300 can collect status data from multiple battery packs 100, maintain synchronization between battery packs 100 and balance the entire rack, control charging and discharging at the system level and manage safety, and communicate with external systems (e.g., the power grid, energy management system, etc.). That is, the rack control unit 300 coordinates the operation of the entire system and controls power flow through communication with external systems. The rack control unit 300 can be a rack control unit (RCU).

[0050] Furthermore, the battery pack control unit 140 is a low-level control device that manages the status of each battery pack. In this way, it can monitor the voltage, current, temperature, etc. of the cells and modules within the battery pack, perform cell balancing, and transmit status data to the main control unit (rack control unit 300). The battery pack control unit 140 can be a battery pack control unit (PCU) or a slave BMS.

[0051] Therefore, when the battery pack control unit 140 collects detailed data of each battery pack (e.g., cell voltage, cell temperature, etc.) and transmits the data to the rack control unit 300, the rack control unit 300 comprehensively analyzes the data and issues control commands to the battery pack control unit 140 as needed.

[0052] The rack control unit 300 is a device for controlling the on / off state of the balance switch B_SW of the cell balancing unit 120 and the EIS switch EIS_SW of the EIS measurement unit 130 based on control signals transmitted from the microcontroller unit (MCU) or battery monitoring IC (BMIC) of the BMS via the battery pack control unit 140. Alternatively, the MCU / BMIC can be configured as the rack control unit 300 or can be a device located outside the BMS for controlling the on / off state of the balance switch B_SW and the EIS switch EIS_SW.

[0053] Hereinafter, a method for managing a battery rack according to an embodiment of the present invention will be described. The method for managing a battery rack according to an embodiment of the present invention can be a method for processing signals received using the battery rack described above, and therefore, since the foregoing description of the battery rack can be applied as is, its redundant description can be omitted.

[0054] Figure 3 This is a diagram illustrating a method for managing a battery rack according to an embodiment of the present invention.

[0055] Reference Figure 3 According to an embodiment of the present invention, the method for balancing battery packs constituting a battery rack first monitors the SOC of each battery pack in the SOC monitoring unit 200 (S10).

[0056] As a result of monitoring (S10), when the difference between the SOC of the first battery pack 100 selected from multiple battery packs and the average SOC of all other battery packs or the SOC of any other battery pack is greater than or equal to a predetermined reference value (S20), the rack control unit 300 controls the first battery pack 100 through the battery pack control unit 140 to perform an EIS measurement operation (S30).

[0057] In the EIS measurement operation, an AC current for EIS measurement is extracted from the first battery pack 100 that requires battery pack balancing to measure the EIS of the first battery pack 100 and to discharge the first battery pack 100. In this case, since the EIS measurement operation is performed in A (amperes), the battery balancing performed by the cell balancing unit 120 is achieved at a significantly faster balancing speed than battery balancing performed in mA.

[0058] Furthermore, as a result of monitoring (S10), when the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs, or when the SOC of any other battery pack drops to or below a predetermined reference value (S20), the EIS measurement operation of the first battery pack 100 is stopped (S40), and cell balancing with other battery packs is performed by discharging via the cell balancing unit 120 (S50). In this case, since the battery balancing current is in mA, the battery balancing operation via the cell balancing unit 120 is slow in terms of balancing speed, but accurate battery balancing is possible.

[0059] For each battery cell in a battery module 111 comprising a first battery pack 100 requiring battery pack balancing, a battery pack balancing operation is performed via cell balancing unit 120 to discharge each cell. For example, the battery pack balancing operation refers to balancing any cell in any other battery pack by discharging each cell of the first battery pack 100 through cell balancing unit 121 of the first battery pack 100.

[0060] In this scenario, the first battery pack 100 may be a new battery pack that has already replaced a problematic battery pack among multiple battery packs included in the battery rack due to faults, etc. For example, the newly replaced battery pack exhibits very little degradation in state of health (SOH), while the currently used existing (unreplaced) normal battery pack exhibits SOH degradation, so the SOC balance between the replaced battery pack and the unreplaced battery pack may not be matched.

[0061] In this manner, when the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs or the SOC of any other battery pack is greater than or equal to a predetermined reference value, the rack control unit 300 performs control such that the cell balancing unit 120 does not operate and only the EIS measurement unit 130 operates, thereby measuring the EIS of the first battery pack 100 and discharging the first battery pack 100. Furthermore, when the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below the predetermined reference value, the EIS measurement operation of the first battery pack 100 stops, and each cell discharges through the cell balancing unit 120.

[0062] This is because, since EIS measurement operations are performed in units of mA, the battery pack balancing performed by the cell balancing unit 120 achieves a significantly faster balancing speed than cell balancing performed in units of mA.

[0063] Therefore, when the SOC of the first battery pack 100 differs from the average SOC of all other battery packs or the SOC of any other battery pack by a predetermined reference value or greater, the first battery pack 100 is rapidly discharged to increase the speed of battery pack balancing. Furthermore, when the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below the predetermined reference value, battery pack balancing is performed slowly but precisely by discharging each cell through the cell balancing unit 120. In this case, the discharge of each cell can proceed until the battery pack is precisely balanced with the other battery packs. That is, precise battery pack balancing is performed by setting a smaller reference value instead of the previously predetermined reference value.

[0064] In other words, according to the configuration of the present invention, when the first battery pack 100 is discharged to balance among the battery packs, the EIS measurement unit 131 of the first battery pack (which is the battery pack that needs to be discharged for initial rapid balancing) is operated to perform rapid discharge, thereby performing the first battery pack balancing. Then, the cell balancing unit 121 is operated to perform precise secondary battery pack balancing. In this case, a predetermined reference value used to determine whether the difference between the SOC of the first battery pack 100 and the average SOC of all other battery packs or the SOC of any other battery pack is greater than or equal to a predetermined reference value is applied as a value smaller than that for the first battery pack balancing in the case of secondary battery pack balancing.

[0065] According to the present invention, although the energy lost when balancing the first battery pack 100 may not be used anywhere in the related art, in the present invention, the discharge energy used to balance the first battery pack 100 can be used to extract EIS measurement data, thereby providing the advantage of utilizing the lost energy.

[0066] In the foregoing, although specific terminology has been used to describe and illustrate exemplary embodiments of the invention, these terms are for the purpose of clearly describing the invention only, and it will be apparent that various modifications and changes can be made to the exemplary embodiments of the invention and the described terminology without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Such modified embodiments should not be construed solely as being within the spirit and scope of the invention, but should be interpreted as falling within the scope of the claims of the invention.

[0067] Meanwhile, the names of the drawing symbols used in this invention are as follows.

[0068] 10: Charge / Discharge switch, 100: Battery pack, 110: Battery module, 120: Cell balancing unit, 121a: Balancing resistor, 130: EIS measurement unit, 131a: EIS resistor, 140: Battery pack control unit, 200: SOC monitoring unit, 300: Rack control unit, 400: External device.

Claims

1. A battery holder, the battery holder comprising: Multiple battery packs, each including an electrochemical impedance spectroscopy (EIS) measurement unit; A state of charge (SOC) monitoring unit, the SOC monitoring unit being configured to monitor the SOC of each of the battery packs; as well as A rack control unit is configured to control the EIS measurement unit of the first battery pack to perform an EIS measurement operation when the SOC of the first battery pack selected from the plurality of battery packs differs from the average SOC value of the other battery packs or from the SOC of any other battery pack by a predetermined reference value or greater.

2. The battery holder according to claim 1, wherein, Each battery pack also includes: A battery module, the battery module comprising one or more battery cells; A cell balancing unit is connected to the positive (+) terminal and the negative (-) terminal of each of the battery cells constituting the battery module to form a cell balancing path through which a cell balancing current flows, and the cell balancing unit is configured to selectively discharge each cell; and A battery pack control unit is configured to control the operation of the cell balancing unit and the EIS measurement unit in the battery pack under the control of the rack control unit.

3. The battery holder according to claim 2, wherein, The rack control unit is configured to: When the SOC of the first battery pack differs from the average SOC of all other battery packs or from the SOC of any other battery pack by a predetermined reference value or greater, the EIS measurement unit of the first battery pack is controlled to perform the EIS measurement operation; and When the difference between the SOC of the first battery pack and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below the predetermined reference value, the EIS measurement operation of the EIS measurement unit of the first battery pack is stopped, and control is executed so that the battery cells of the first battery pack are balanced with the cells of the other battery packs through the cell balancing unit of the first battery pack.

4. The battery holder according to claim 3, wherein, The cell balancing unit includes: A balancing resistor is formed on the cell balancing path, through which cell current flows via a connection between the positive (+) and negative (-) terminals of each battery cell, and the balancing resistor is configured to generate a cell potential difference due to the cell current flowing in the cell balancing path; and A balance switch (B_SW) is formed on the cell balancing path and configured to perform cell balancing operations by switching the cell balancing path on / off. The balance switch is controlled to be turned on / off by the control signal of the rack control unit.

5. The battery holder according to claim 3, wherein, The EIS measurement unit includes: An EIS measuring resistor forms an EIS measuring path, through which an EIS current (AC current for EIS measurement) flows via a connection between the positive (+) and negative (-) terminals of a battery module comprising one or more battery cells, and the EIS measuring resistor is configured to generate an EIS potential difference due to the EIS current flowing in the EIS measuring path; and An EIS current switch (EIS_SW) is formed on the EIS measurement path and configured to discharge the battery module simultaneously with the EIS measurement operation of the battery module by turning the EIS measurement path on / off at predetermined intervals. The EIS current switch is selectively controlled to be on / off via the control signal from the rack control unit.

6. The battery holder according to claim 2, wherein, The rack control unit performs control such that when battery pack balancing is required, one of the cell balancing unit and the EIS measurement unit is selectively operated.

7. The battery holder according to claim 1, wherein, The rack control unit is a device for controlling the on / off state of the balance switch (B_SW) of the cell balancing unit and the EIS switch (EIS_SW) of the EIS measurement unit based on control signals sent from the microcontroller unit (MCU) or battery monitoring IC (BMIC) of the battery management system (BMS). Alternatively, the MCU / BMIC may be configured as the rack control unit, or it may be located outside the BMS for controlling the on / off state of the balance switch (B_SW) and the EIS switch (EIS_SW).

8. A method for managing a battery rack, the method for managing a battery rack being used to balance multiple battery packs constituting the battery rack, the method for managing the battery rack comprising: SOC monitoring steps, wherein the SOC monitoring steps monitor the SOC of each battery pack in the SOC monitoring unit; The EIS measurement step, wherein, as a result of the monitoring, if the difference between the SOC of a first battery pack selected from the plurality of battery packs and the average SOC of all other battery packs or the SOC of any other battery pack is greater than or greater than a predetermined reference value, control is executed in the rack control unit to perform an EIS measurement operation in the first battery pack; and In the cell balancing step, when, as a result of the monitoring, the difference between the SOC of the first battery pack and the average SOC of all other battery packs or the SOC of any other battery pack decreases to or below the predetermined reference value, the EIS measurement operation of the first battery pack is stopped in the rack control unit, and control is executed to balance the cells of the first battery pack with those of the other battery packs via discharge through the cell balancing unit.

9. The method for managing a battery rack according to claim 8, wherein, In the cell balancing step, balancing is performed with any cell in any other battery pack by discharging each cell of the first battery pack via the cell balancing unit of the first battery pack.

10. The method for managing a battery rack according to claim 8, wherein, In the EIS measurement step, an AC current for EIS measurement is extracted from the first battery pack to measure the EIS of the first battery pack and the first battery pack is discharged.

11. The method for managing a battery rack according to claim 8, wherein, In the cell balancing step, each cell set for each cell balancing path is discharged, the cell balancing path being formed by connecting the positive (+) terminal and the negative (-) terminal of each of the battery cells constituting the battery module included in the first battery pack, and cell current flows through the cell balancing path.

12. The method for managing a battery rack according to claim 8, wherein, In the EIS measurement step, when the SOC of the first battery pack differs from the SOC of the other battery packs by a predetermined reference value or greater, the cell balancing operation through the cell balancing unit is not performed, and only the EIS measurement is performed. In the cell balancing step, when the difference between the SOC of the first battery pack and the SOC of the other battery packs drops to or below the predetermined reference value, the EIS measurement operation is stopped and control is executed to perform the cell balancing operation through the cell balancing unit.

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