Battery management device, battery system, and battery module assembly balancing method

Abstract

A battery system according to an embodiment of the present invention is a battery system which includes a battery rack including a plurality of battery module assemblies (BMAs). The battery system may comprise: a first battery management device (RBMS) which controls the battery rack, the first battery management device identifying, at predetermined periods, a condition for performing BMA balancing according to a state of charge and whether the battery system is in an idle state, and if the condition for performing BMA balancing is satisfied, setting a BMA balancing target and a BMA balancing time; and a second battery management device (PBMS) which is located in each of the BMAs and includes a balancing circuit, the second battery management device receiving a BMA balancing command including the BMA balancing target and the BMA balancing time from the first battery management device to perform cell balancing.

Description

Battery management device, battery system, and battery module assembly balancing method

[0001] This application claims the benefit of Korean Patent Application No. 10-2023-0075256 filed with the Korean Intellectual Property Office on June 13, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a battery management device, a battery system, and a method for balancing a battery module assembly, and more particularly, to a battery management device, a battery system, and a method for balancing a battery module assembly that perform balancing between battery module assemblies in a battery rack including a plurality of battery modules.

[0003] Secondary batteries, which can be recharged and reused after use, are manufactured into battery modules or packs by connecting multiple battery cells in series according to the output capacity required by the device. These batteries serve as power sources for various devices. These batteries are used in a wide range of applications, from small, high-tech electronic devices like smartphones to electric bicycles, electric vehicles, and energy storage systems (ESS).

[0004] A battery module or battery pack is a structure composed of multiple battery cells. If any of the battery cells experience overvoltage, overcurrent, or overheating, this can compromise the safety and operational efficiency of the battery module or pack. Therefore, a means of detecting these issues is essential. Therefore, battery modules or battery packs are equipped with a Battery Management System (BMS), which measures the voltage values ​​of each battery cell and monitors and controls the voltage status of the cells based on these measured values.

[0005] Meanwhile, voltage variations between battery cells can occur due to various factors. These variations can be reduced through cell balancing by the BMS. However, when replacing battery modules in a system containing multiple battery modules, the existing cell balancing function alone cannot provide efficient inter-module and inter-cell balancing.

[0006] An object of the present invention to solve the above problems is to provide a battery management device that performs balancing between battery module assemblies.

[0007] Another object of the present invention to solve the above problems is to provide a balancing method between battery module assemblies.

[0008] Another object of the present invention to solve the above problems is to provide a battery system that performs balancing between battery module assemblies.

[0009] According to one embodiment of the present invention for achieving the above object, a battery management device is provided that controls a battery rack including a plurality of battery module assemblies (BMAs), and may include a control unit and a memory that stores at least one command executed through the control unit, wherein the at least one command may include a command for periodically checking a BMA balancing performance condition according to whether the battery rack is in an idle state and a state of charge; and a command for setting a BMA balancing target and a BMA balancing time to perform BMA balancing when the BMA balancing performance condition is satisfied.

[0010] Here, whether the battery rack is in an idle state can be determined based on whether the current flowing through the battery rack is less than a preset current threshold.

[0011] The command to check the conditions for performing the above BMA balancing may include a command to check whether the battery system remains in an idle state for a certain period of time or longer; and a command to determine whether the state of charge of the battery rack exceeds a set threshold.

[0012] The command to perform the above BMA balancing may include a command to calculate the SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system; and a command to select all cells in the BMA as balancing targets when the SOC deviation of the BMA compared to the minimum SOC is greater than or equal to an SOC deviation threshold.

[0013] The at least one command may further include a command to transmit a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

[0014]

[0015] According to one embodiment of the present invention for achieving the above-described other object, a battery module assembly balancing method is provided, which is a BMA balancing method in a battery rack including a plurality of battery module assemblies (BMA), the method including: a step of a first battery management device controlling the battery rack periodically checking a BMA balancing performance condition according to whether a battery system including the battery rack is in an idle state and a state of charge; and a step of the first battery management device performing BMA balancing by setting a BMA balancing target and a BMA balancing time when the BMA balancing performance condition is satisfied.

[0016] The step of checking the above BMA balancing performance conditions may include a step of checking whether the battery system remains in an idle state for a certain period of time without performing charging and discharging; and a step of determining whether the state of charge of the battery system exceeds a set standard.

[0017] The step of performing the above BMA balancing may include the step of calculating the SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system; and the step of selecting all cells in the BMA as balancing targets when the SOC deviation of the corresponding BMA compared to the minimum SOC is equal to or greater than an SOC deviation threshold.

[0018] In addition, the BMA balancing method may further include a step of transmitting a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

[0019] The above BMA balancing method may further include a step in which a second battery management device within a BMA to be balanced receives the BMA balancing command; and a step in which the second battery management device performs cell balancing on all cells within the BMA to be balanced using an internal balancing circuit.

[0020] The above BMA balancing method may further include a step of the second battery management device determining whether the SOC deviation of each cell falls within a range greater than or equal to a first value and less than or equal to a second value, and performing cell balancing on each cell in which the SOC deviation of the cell falls within a range greater than or equal to the first value and less than or equal to the second value.

[0021] Here, the SOC deviation threshold for the BMA balancing can be set equal to the first value.

[0022] Meanwhile, whether the battery system is in an idle state can be determined based on whether the current flowing through the battery rack is below a preset current threshold.

[0023]

[0024] According to another embodiment of the present invention for achieving the above-described further object, a battery system may include a battery rack including a plurality of battery module assemblies (BMAs), a first battery management device controlling the battery rack, the first battery management device periodically checking a BMA balancing performance condition according to whether the battery rack is in an idle state and a state of charge, and setting a BMA balancing target and a BMA balancing time when the BMA balancing performance condition is satisfied; and a second battery management device located within the BMA and including a balancing circuit, the second battery management device performing cell balancing by receiving a BMA balancing command including the BMA balancing target and the BMA balancing time from the first battery management device.

[0025] The BMA balancing performance condition can be confirmed by checking whether the battery rack remains in an idle state for a certain period of time without performing charging and discharging and determining whether the state of charge of the battery rack exceeds a set threshold.

[0026] The first battery management device may also calculate an SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system, and if the SOC deviation of the corresponding BMA compared to the minimum SOC is equal to or greater than an SOC deviation threshold, select all cells in the corresponding BMA as balancing targets, and transmit a BMA balancing command including information on the selected balancing target and a set balancing time to the target BMA.

[0027] Meanwhile, the second battery management device can receive the BMA balancing command from the first battery management device and perform cell balancing for all cells in the corresponding BMA to be balanced during the balancing time using the balancing circuit.

[0028] In addition, the second battery management device can also perform a general cell balancing operation as examined through Fig. 2. That is, the second battery management device determines whether the SOC deviation of each cell with respect to the minimum cell SOC falls within a range of a first value or more and a second value or less, and can perform cell balancing for each cell whose SOC deviation falls within a range of the first value or more and the second value or less. In this case, the first value may be, for example, 2.5%, and the second value may be, for example, 10%.

[0029] At this time, the minimum cell SOC among the cell SOCs of the plurality of cells in the battery system can be calculated by the RBMS, which is the first battery management device. That is, the RBMS can obtain battery status information from the plurality of second battery management devices, calculate the minimum cell SOC, and provide the calculated information to the plurality of second battery management devices.

[0030] Meanwhile, the SOC deviation threshold for performing BMA balancing according to the present invention can be set to be the same as the cell SOC deviation lower limit value of general cell balancing conditions.

[0031] According to the above-described embodiment of the present invention, inter-module balancing can be performed using an existing cell balancing circuit without adding a separate hardware configuration for inter-module balancing and without interfering with the existing general cell balancing function.

[0032] Therefore, when replacing or expanding a battery module assembly in a system including multiple battery module assemblies, the SOC deviation between the battery module assemblies can be efficiently adjusted.

[0033] Figure 1 is a block diagram of a battery module assembly and a battery management device to which the present invention can be applied.

[0034] Figure 2 is a conceptual diagram illustrating general cell balancing.

[0035] Figure 3 is a drawing to explain the problem of cell balancing when replacing a battery module assembly in an existing battery system.

[0036] Figure 4 shows the operation sequence of a balancing method between battery module assemblies according to an embodiment of the present invention.

[0037] Figure 5 shows a detailed operation sequence of a preprocessing step according to an embodiment of the present invention.

[0038] Figure 6 shows a detailed operation sequence of an entry condition determination step according to an embodiment of the present invention.

[0039] Figure 7 shows a detailed operation sequence of a BMA balancing execution step according to an embodiment of the present invention.

[0040] Figure 8 is a block diagram of a rack BMS and a pack BMS according to an embodiment of the present invention.

[0041] FIG. 9 is a drawing for explaining the BMA balancing concept and balancing performance result according to an embodiment of the present invention when replacing the BMA.

[0042] 100: Battery Module Assembly (BMA)

[0043] 110: PBMS (Pack BMS)

[0044] 111: Control Unit

[0045] 113: Cell Balancing Module

[0046] 115: Communication module

[0047] 200: RBMS

[0048] 210: Control Unit

[0049] 220: Communication module

[0050] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0051] Terms such as "first," "second," "A," and "B" may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, the first component could be referred to as the "second component," and similarly, the second component could also be referred to as the "first component." The term "and / or" includes any combination of multiple related items listed or any one of multiple related items listed.

[0052] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0053] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0054] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0055]

[0056] Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings.

[0057]

[0058] Figure 1 is a block diagram of a battery module assembly and a battery management device to which the present invention can be applied.

[0059] Referring to FIG. 1, each battery module assembly (100) may be configured to include a plurality of battery cells connected in series. The most commonly used battery cell is a lithium ion (Li-Ion) battery cell. The battery module is connected to a load through positive and negative terminals and can perform a charge / discharge operation. The battery modules may be connected in series / parallel according to the requirements of the system in which the battery is used, and the example illustrated in FIG. 1 shows a form in which the battery module assemblies (100) are connected in series.

[0060] The battery module assembly (100) typically includes a pack battery management system (PBMS) for managing a battery module (or battery pack) including a plurality of battery cells connected in series. The PBMS (110) according to the present invention may include various components such as a fuse, a current sensing element, a thermistor, a switch, and a balancer, and may be implemented in the form of a PCB (Printed Circuit Board). In other words, the battery module assembly (100) is a module including a plurality of cells and a PBMS PCB, and may be connected in series with other battery module assemblies to form a battery rack, as illustrated in FIG. 1.

[0061] The Pack Battery Management System (PBMS; 110) monitors the current, voltage, and temperature of each battery module under its control, calculates the State of Charge (SOC) based on the monitoring results, and controls charging and discharging. Here, the State of Charge (SOC) is the battery's charged state (or charge amount) expressed as a percentage [%].

[0062] In this way, the PBMS (110) can monitor battery cells, read cell voltages, and transmit the information to the RBMS (Rack BMS) and further to other components, devices, and systems connected to the battery. The RBMS (200) is a BMS that manages a rack including multiple battery module assemblies (BMAs) and is linked to the PBMS of each battery module assembly. In the present invention, unlike the PBMS (110), the RBMS (200) does not include a separate balancing circuit internally.

[0063] Meanwhile, the PBMS (110) and RBMS (200) may include a communication module within the device for mutual communication and for communication with other devices or systems within the device including the battery system. The communication module of the BMS may communicate with other systems within the device using a communication method such as CAN (Controller Area Network) or Ethernet. When CAN communication is used, components, modules, or systems within the BMS are connected to each other via the CAN bus.

[0064] Meanwhile, the characteristics of multiple battery cells included in a battery module cannot be completely identical, and voltage deviations may occur between cells connected in series due to natural discharge of each cell, environmental factors during use, etc. The PBMS (110) may include a cell balancing (CB: Cell Balancing) circuit that performs a balancing operation to evenly balance the charges of the battery cells in order to extend the life of the battery pack. The capacity of the cell balancing circuit may be limited in terms of hardware. For example, the cell balancing capacity that can be provided may be limited due to limitations in the wattage, resistance value, and thermal endurance of the CB circuit.

[0065] Additionally, the PBMS (110) may include an MCU (Micro Controller Unit) or BMIC (Battery Monitoring Integrated Chip) for controlling the internal components described above in conjunction with each other. Here, the BMIC may be an IC-type component located within the BMS and measuring information such as voltage, temperature, and current of the battery cell / module.

[0066] In the present invention, the BMIC can measure the voltage of cells in the battery module assembly to which it belongs according to the command of the RBMS (200) and report it to the RBMS (200), and can perform the role of controlling ON / OFF of the FET (Field Effect Transistor) element in the balancing circuit.

[0067]

[0068] Figure 2 is a conceptual diagram illustrating general cell balancing.

[0069] As illustrated in Fig. 2, multiple battery cells contained within a battery module experience SOC variations among cells due to natural discharge of each cell, environmental factors during use, etc. To reduce SOC variations, cell balancing performed by a PBMS is typically performed by placing a circuit including a switch (e.g., a transistor) and a resistor for each cell, and a control unit controls the balancing circuit.

[0070] Cell balancing operation can be performed by discharging cells having SOC deviations within a certain range having upper and lower limits based on the lowest SOC. Cell balancing can be performed by discharging individual cells having SOC deviations in the range of, for example, 2.5% to 10%. In the example of Fig. 2, it can be confirmed that cell balancing is performed for cells 1, 3, and 5, in which the lowest SOC is 54% in one module and deviations of 2.5% to 10% based on the lowest SOC are present. Here, 2.5% can be defined as a lower limit of cell SOC deviation for cell balancing, and 10% can be defined as an upper limit of cell SOC deviation for cell balancing.

[0071] Here, for example, the SOC deviation range for cell balancing refers to the SOC deviation between cell groups, and represents the SOC process error range that may occur in a battery cell production line. Cells that exceed the inter-group deviation, such as cell 4 in Figure 2 with an SOC of 65%, are judged as defective cells and are not subject to cell balancing, but rather their defective status is highlighted.

[0072] Meanwhile, in such a situation, when replacing some of the multiple BMAs within the battery system, there are many cases where a new, unused BMA is applied to the battery use field as is. In this case, the SOC of the new BMA may deviate more significantly from the SOC of the BMA that was already installed and in use.

[0073]

[0074] Figure 3 is a drawing to explain the problem of cell balancing when replacing a battery module assembly in an existing battery system.

[0075] Looking at the example in Fig. 3, the SOC of BMA3 used in the existing system is 41.25%, the average cell SOC of the newly added BMA1 is 69.5%, and the average cell SOC of BMA2 is 49.75%. At this time, the lowest cell SOC among the cell SOCs in the system is 39%, and cell balancing can be performed only for cells with a SOC deviation within 10% based on this. That is, cell balancing is performed only for cells 2 and 4 in BMA2 in the newly added BMA, and cell balancing is not performed for all cells in BMA1, and the remaining cells except cells 2 and 4 in BMA2. Accordingly, a problem occurs in which SOC deviations remain between cells even after cell balancing is performed, even though they are normal cells.

[0076] Ultimately, conventional cell balancing is not performed on cells with an SOC deviation of more than 10% compared to the lowest cell SOC for all cells, and the SOC deviation between BMAs causes a deterioration in the charge / discharge performance of the battery.

[0077] The present invention is proposed to solve these problems and provides a method for balancing a battery rack including a two-stage balancing operation (balancing between battery module assemblies and general cell balancing).

[0078]

[0079] Figure 4 shows the operation sequence of a balancing method between battery module assemblies according to an embodiment of the present invention.

[0080] The method for balancing battery module assemblies according to an embodiment of the present invention may be performed by a rack BMS, i.e., a battery management device that manages battery racks, or a control unit within the device. The method for balancing battery racks according to an embodiment of the present invention may also be performed by a rack BMS and a pack BMS.

[0081] A method for balancing between battery module assemblies according to an embodiment of the present invention may largely include a preprocessing (S100) step, an entry condition determination (S200) step, and a BMA balancing performance (S300) step.

[0082] The preprocessing (S100) step is a step to check the balancing execution cycle, determine whether the cycle has been reached, and decide whether to proceed to the entry condition judgment step.

[0083] The entry condition judgment (S200) step is a step to determine whether the conditions for performing BMA balancing are satisfied, such as whether the battery is in a resting state and whether an appropriate SOC for performing balancing is secured.

[0084] That is, through the preprocessing (S100) step and the entry condition determination (S200) step according to the embodiment of the present invention, the BMA balancing performance conditions can be confirmed depending on whether the battery system is in an idle state and the state of charge.

[0085] In the BMA balancing execution step (S300), a BMA to be balanced is selected and a balancing time is set. Furthermore, a balancing execution command and balancing time are transmitted to the selected target BMA, causing the PBMS within the target BMA to perform balancing using a cell balancing circuit.

[0086] In summary, a battery module assembly balancing method according to an embodiment of the present invention is a BMA balancing method in a battery rack including a plurality of battery module assemblies (BMA), the method including: a step of a first battery management device controlling the battery rack periodically checking a BMA balancing performance condition according to whether a battery system including the battery rack is in an idle state and a state of charge; and a step of the first battery management device performing BMA balancing by setting a BMA balancing target and a BMA balancing time when the BMA balancing performance condition is satisfied.

[0087] The step of checking the above BMA balancing performance conditions may include a step of checking whether the battery system remains in an idle state for a certain period of time without performing charging and discharging; and a step of determining whether the state of charge of the battery system exceeds a set standard.

[0088] The step of performing the above BMA balancing may include the step of calculating the SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system; and the step of selecting all cells in the BMA as balancing targets when the SOC deviation of the corresponding BMA compared to the minimum SOC is equal to or greater than an SOC deviation threshold.

[0089] In addition, the BMA balancing method may further include a step of transmitting a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

[0090] The above BMA balancing method may further include a step in which a second battery management device within a BMA to be balanced receives the BMA balancing command; and a step in which the second battery management device performs cell balancing on all cells within the BMA to be balanced using an internal balancing circuit.

[0091] The above BMA balancing method may further include a step of the second battery management device determining whether the SOC deviation of each cell falls within a range greater than or equal to a first value and less than or equal to a second value, and performing cell balancing on each cell in which the SOC deviation of the cell falls within a range greater than or equal to the first value and less than or equal to the second value.

[0092] Here, the SOC deviation threshold for the BMA balancing can be set equal to the first value.

[0093] Meanwhile, whether the battery system is in an idle state can be determined based on whether the current flowing through the battery rack is below a preset current threshold.

[0094]

[0095] Figure 5 shows a detailed operation sequence of a preprocessing step according to an embodiment of the present invention.

[0096] Specifically, in the preprocessing (S100) step, for example, if the balancing execution cycle is set to one day (24 hours), it is checked whether the count variable Day_count has reached 86400 (S110), and if it has not reached that value, the value of the variable Day_count is increased by 1 (S120). The step (S110) of checking whether the count variable Day_count has reached 86400 (=60*60*24) is performed at a cycle of 1 second, and for example, if Day_count reaches 86400 after one day from the initial value of 0, it can be known that one day, which is the balancing execution cycle, has arrived. In this case, the value of the variable Day_flag, which notifies that the balancing cycle has been reached, is set to "1", and the value of the count variable Day_count is initialized to "0" (S130).

[0097]

[0098] Figure 6 shows a detailed operation sequence of an entry condition determination step according to an embodiment of the present invention.

[0099] Referring to Fig. 6, in the entry condition determination step for performing balancing, the variable Day_flag value is checked to see if one day, which is the balancing execution cycle, has passed (S201). As previously discussed in Fig. 5, the variable Day_flag value is set to 1 after one day has passed. Therefore, if the balancing execution cycle, for example, one day, has passed since the previous balancing execution, the entry condition determination procedure is not performed and is immediately terminated (No in S201).

[0100] If the value of the variable Day_flag is 1 (YES in S201), it is checked whether the target BMA for balancing has already been set (S210). If the balancing target BMA has already been set (NO in S210), the subsequent procedure is not performed and the procedure is terminated.

[0101] If the target BMA is not set (i.e., target BMA = 0), the following procedure is performed to check whether the battery is in an idle state (S220). Whether the battery is in an idle state is determined by whether the current flowing through the battery is greater than the current threshold (I th ) can be checked to see if it is less than the current threshold (I). Here, the current threshold (I th ) can be set to, for example, 1.89A, but is not limited to that value. If the battery is in a dormant state, it is additionally checked whether a certain period of time has passed in the dormant state (S230). Here, the certain period of time can be set to, for example, 30 minutes.

[0102] If the battery has been in an idle state for a certain period of time, it is checked whether the SOC of the battery is higher than a certain reference value (SOC_th) (S240), and if this is satisfied, the process proceeds to the next step. Here, the SOC of the battery may be the average SOC value of multiple BMAs included in the battery system. Here, the certain reference value for SOC may be set to, for example, 46%, but the scope of the present invention is not limited to that value.

[0103] In summary, the entry condition judgment step is a step to determine whether the conditions for performing BMA balancing are satisfied. It is a procedure to check whether the battery has been in an idle state for a certain period of time or longer and whether the battery's charge rate is sufficient to perform balancing.

[0104]

[0105] Figure 7 shows a detailed operation sequence of a BMA balancing execution step according to an embodiment of the present invention.

[0106] In the BMA balancing execution step illustrated in Fig. 7, a BMA to be balanced is selected, a balancing time is set, and a balancing execution command and information about the balancing time are transmitted to the selected target BMA.

[0107] More specifically, the value of the variable n for representing the BMA is set to 0 (S310), and it is checked whether the value of the variable n reaches the total number of BMAs in the system (S320). If the value of n does not reach the total number of BMAs (example of S320), the SOC deviation between the BMAs (BMA_soc_diff), which is defined as the difference value between the SOC of the BMA (BMA_SOC[n]) and the SOC of the minimum BMA (Min_BMA_SOC) (S330), is greater than the SOC deviation threshold (SOC_ diff_th ) is checked (S350). If the SOC deviation of the corresponding BMA is greater than the SOC deviation threshold, all cells within the corresponding BMA (e.g., 14 cells within one BMA) are selected as balancing targets (S370). The operations of S330, S350, and S370 described above are performed for all BMAs within the system while increasing the variable n (S351).

[0108] Meanwhile, when the SOC deviation comparison and balancing target selection for all BMAs are completed (NO in S320), it is checked again whether the balancing target is set (S340), and the balancing time is set (S341). At this time, the balancing time can be set to a value of, for example, 8245 seconds (= cell capacity (71 Ah) * 3600 seconds * cell balancing amount (0.1%) / balancing current (31 mA)), but is not limited thereto.

[0109] Once the balancing target and balancing time are determined, the balancing command and balancing time information are transmitted to the balancing target BMA (S390). At this time, multiple balancing target BMAs may be set, and in this case, the balancing command and balancing time information may be transmitted to each PBMS of the multiple target BMAs.

[0110]

[0111] Figure 8 is a block diagram of a rack BMS and a pack BMS according to an embodiment of the present invention.

[0112] As previously discussed in FIG. 1, the rack BMS (200) is interconnected with all battery module assemblies (BMA) included in the rack, and for this purpose, communicates with the PBMS (110) within each battery module assembly.

[0113] Referring to FIG. 8, the pack BMS (110) according to the present invention may include a control unit (MCU; Micro Control Unit) (111), a cell balancing module (113), and a communication module (115). In this specification, the control unit may be referred to as a processor, a controller, an MCU, etc., and may also mean a dedicated processor in which methods according to embodiments of the present invention are performed. In addition, the control unit (111) may be provided in the form of a BMIC (Battery Monitoring Integrated Chip). The BMIC located in each pack BMS (110) measures the voltage of each cell according to a command from the RBMS (200), reports it to the RBMS (200), and can control ON / OFF of the FET element in the balancing circuit.

[0114] The RBMS (200) may include a control unit (210) and a communication module (220), and the control unit (210) of the RBMS (200) may calculate the BMA voltage from each cell voltage measured and reported by the BMIC and derive the BMA SOC therefrom. The control unit (210) selects a BMA balancing target using the derived BMA SOC and transmits information about the selected target to the control unit (111, for example, BMIC) of the pack BMS (110). The control unit of the pack BMS (110) that receives the information performs balancing on the target cell using the cell balancing circuit (113). Here, the balancing may be a discharge operation on each cell performed for a set balancing time.

[0115] In summary, the battery system according to the present invention may include a battery system including a battery rack including a plurality of battery module assemblies (BMAs), a first battery management system (RBMS) for controlling the battery rack, the first battery management system periodically checking a BMA balancing performance condition depending on whether the battery system is in an idle state and a state of charge, and setting a BMA balancing target and a BMA balancing time when the BMA balancing performance condition is satisfied; and a second battery management system (PBMS) located in the BMA and including a balancing circuit, the second battery management system performing cell balancing by receiving a BMA balancing command including the BMA balancing target and the BMA balancing time from the first battery management system.

[0116] The first battery management device can determine whether the battery system remains in an idle state for a certain period of time or longer and determine whether the state of charge of the battery system exceeds a set threshold to determine the conditions for performing the BMA balancing.

[0117] The first battery management device may also calculate an SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system, and if the SOC deviation of the corresponding BMA compared to the minimum SOC is equal to or greater than an SOC deviation threshold, select all cells in the corresponding BMA as balancing targets, and transmit a BMA balancing command including information on the selected balancing target and a set balancing time to the target BMA.

[0118] Meanwhile, the second battery management device can receive the BMA balancing command from the first battery management device and perform cell balancing for all cells in the corresponding BMA to be balanced during the balancing time using the balancing circuit.

[0119] In addition, the second battery management device can also perform a general cell balancing operation as examined through Fig. 2. That is, the second battery management device determines whether the SOC deviation of each cell with respect to the minimum cell SOC falls within a range of a first value or more and a second value or less, and can perform cell balancing for each cell whose SOC deviation falls within a range of the first value or more and the second value or less. In this case, the first value may be, for example, 2.5%, and the second value may be, for example, 10%.

[0120] At this time, the minimum cell SOC among the cell SOCs of the plurality of cells in the battery system can be calculated by the RBMS, which is the first battery management device. That is, the RBMS can obtain battery status information from the plurality of second battery management devices, calculate the minimum cell SOC, and provide the calculated information to the plurality of second battery management devices.

[0121] Meanwhile, the SOC deviation threshold for performing BMA balancing according to the present invention can be set to be the same as the SOC deviation lower limit value of general cell balancing conditions.

[0122] In addition, a rack battery management device (200) according to the present invention is a battery management device that controls a battery rack including a plurality of battery module assemblies (BMAs), and may include a control unit and a memory that stores at least one command executed through the control unit, wherein the at least one command may include a command for periodically checking a BMA balancing performance condition according to whether the battery system is in an idle state and a state of charge; and a command for setting a BMA balancing target and a BMA balancing time to perform BMA balancing when the BMA balancing performance condition is satisfied.

[0123] Here, whether the battery system is in an idle state can be determined based on whether the current flowing through the battery rack is below a preset current threshold.

[0124] The command to check the conditions for performing the above BMA balancing may include a command to check whether the battery system remains in an idle state for a certain period of time or longer; and a command to determine whether the state of charge of the battery system exceeds a set threshold.

[0125] The command to perform the above BMA balancing may include a command to calculate the SOC deviation of each BMA compared to a BMA having a minimum SOC in the battery system; and a command to select all cells in the BMA as balancing targets when the SOC deviation of the BMA compared to the minimum SOC is greater than or equal to an SOC deviation threshold.

[0126] The at least one command may further include a command to transmit a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

[0127]

[0128] FIG. 9 is a drawing for explaining the BMA balancing concept and balancing performance result according to an embodiment of the present invention when replacing the BMA.

[0129] As discussed above, the BMA balancing according to the present invention corrects the SOC of the BMA in which the SOC deviation occurs when the SOC deviation exceeds the SOC deviation threshold (e.g., 2.5%) based on the BMA with the lowest SOC. That is, discharging is performed on all cells in the BMA in which the deviation occurs. The SOC deviation is a deviation between BMAs unrelated to defective cells. The BMA balancing according to the present invention for resolving the SOC deviation is mainly performed for the purpose of minimizing the SOC deviation when replacing the BMA, and is performed prior to performing a general cell balancing operation.

[0130] More specifically, referring to FIG. 9, it is assumed that BMA1 and BMA2 are newly installed in a situation where the SOC of BMA3 used in the existing system is 41.25%. The SOC of the newly added BMA1 is 69.5%, and the SOC of BMA2 is 49.75%. According to an embodiment of the present invention, the SOC of each BMA is compared, and at this time, the SOC of the BMA can be set to the average SOC of all cells included in the BMA.

[0131] In the system illustrated in Fig. 9, the lowest BMA SOC is 41.25%, and both the SOC of BMA1 and the SOC of BMA2 have an SOC deviation of 2.5% or more from the lowest BMA SOC. Therefore, BMA balancing according to the present invention is performed on BMA1 and BMA2, and as a result of the balancing, both the SOC of BMA1 and BMA2 are adjusted to have a BMA SOC of 43.75%.

[0132] After BMA balancing, cell balancing can be performed for each cell, and cell balancing for each cell can be performed in the same operation as the general cell balancing as seen in Fig. 2. Meanwhile, the SOC deviation threshold for performing BMA balancing according to the present invention can be set to be the same as the cell SOC deviation lower limit value of the general cell balancing condition.

[0133] In the present invention, through this embodiment, balancing between modules can be performed using an existing cell balancing circuit without adding a separate configuration for balancing between modules and without interfering with the existing general cell balancing function.

[0134] Therefore, when replacing or expanding a battery module assembly in a system including multiple battery module assemblies, the SOC deviation between the battery module assemblies can be efficiently adjusted.

[0135]

[0136] The operations of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores data readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0137] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0138] While some aspects of the present invention have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most significant method steps may be performed by such a device.

[0139] Although the present invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A battery management device that controls a battery system including a plurality of battery module assemblies (BMA), processor; and A memory that stores at least one instruction to be executed through the processor, At least one of the above commands, A command to periodically check whether the battery system is in an idle state and the condition for performing BMA balancing depending on the state of charge; and A battery management device, comprising a command to perform BMA balancing by setting a BMA balancing target and a BMA balancing time when the above BMA balancing performance condition is satisfied.

2. In claim 1, The command to check the above BMA balancing execution conditions is: A command to check whether the above battery system remains in an idle state for a certain period of time without performing charging and discharging; and A battery management device comprising a command to determine whether the state of charge of the battery system exceeds a set standard.

3. In claim 1, The command to perform the above BMA balancing is: A command to calculate the SOC deviation of each BMA compared to the BMA having the minimum SOC (State of Charge) in the above battery system; and A battery management device including a command to select all cells within the BMA as balancing targets when the SOC deviation of the BMA compared to the minimum SOC is greater than or equal to the SOC deviation threshold.

4. In claim 3, At least one of the above commands, A battery management device further comprising a command to transmit a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

5. In claim 1, Whether the above battery system is in a dormant state, A battery management device, which determines whether the current flowing through the battery system is less than a preset current threshold.

6. A method for balancing a battery module assembly (BMA) in a battery rack including a plurality of battery module assemblies, A step in which a first battery management device controlling the battery rack periodically checks whether the battery system including the battery rack is in an idle state and a condition for performing BMA balancing according to a state of charge; and A battery module assembly balancing method, comprising a step of performing BMA balancing by setting a BMA balancing target and a BMA balancing time when the BMA balancing performance condition is satisfied by the first battery management control device.

7. In claim 6, The step of checking the above BMA balancing performance conditions is: A step of checking whether the above battery system remains in a rest state for a certain period of time without performing charging and discharging; and A method for balancing a battery module assembly, comprising the step of determining whether the state of charge of the battery system exceeds a set standard.

8. In claim 6, The steps of performing the above BMA balancing are: A step of calculating the SOC deviation of each BMA compared to the BMA having the minimum SOC in the above battery system; and A battery module assembly balancing method, comprising a step of selecting all cells within the BMA as balancing targets when the SOC deviation of the BMA relative to the minimum SOC is greater than or equal to the SOC deviation threshold.

9. In claim 8, A battery module assembly balancing method further comprising the step of transmitting a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

10. In claim 9, A step in which a second battery management device within a balancing target BMA receives the BMA balancing command; and A battery module assembly balancing method, further comprising a step of performing cell balancing on all cells within the corresponding BMA to be balanced using an internal balancing circuit of the second battery management device.

11. In claim 10, The above second battery management device, A battery module assembly balancing method, further comprising the step of determining whether the SOC deviation of each cell falls within a range greater than or equal to a first value and less than or equal to a second value, and performing cell balancing on each cell whose SOC deviation falls within a range greater than or equal to the first value and less than or equal to the second value.

12. In claim 11, A battery module assembly balancing method, wherein the SOC deviation threshold for BMA balancing is set equal to the first value.

13. In claim 6, A method for balancing a battery module assembly, wherein whether the above battery system is in an idle state is determined based on whether the current flowing through the battery rack is below a preset current threshold.

14. A battery system comprising a battery rack including a plurality of battery module assemblies (BMA), A first battery management device that controls the battery rack, the first battery management device checking BMA balancing performance conditions based on whether the battery rack is in an idle state and a state of charge at regular intervals, and setting a BMA balancing target and BMA balancing time when the BMA balancing performance conditions are satisfied; and A battery system comprising a second battery management device located within a BMA and including a balancing circuit, the second battery management device receiving a BMA balancing command including the BMA balancing target and BMA balancing time from the first battery management device to perform cell balancing.

15. In claim 14, The above first battery management device, A battery system that checks whether the battery rack remains in an idle state for a certain period of time without performing charge and discharge and determines whether the state of charge of the battery rack exceeds a set threshold to check the condition for performing the BMA balancing.

16. In claim 14, The above first battery management device, A battery system that calculates the SOC deviation of each BMA compared to a BMA having a minimum SOC within the battery system, and selects all cells within the BMA as balancing targets when the SOC deviation of the BMA compared to the minimum SOC is greater than or equal to a SOC deviation threshold.

17. In claim 16, The above first battery management device, A battery system that transmits a BMA balancing command including information about the selected balancing target and the set balancing time to the target BMA.

18. In claim 17, The second battery management device, A battery system that receives the BMA balancing command from the first battery management device and performs balancing for all cells in the corresponding BMA to be balanced during the balancing time using the balancing circuit.

19. In claim 18, The second battery management device, A battery system that determines whether the SOC deviation of each cell compared to the minimum cell SOC falls within a range greater than or equal to a first value and less than or equal to a second value, and performs cell balancing for each cell in which the SOC deviation of the cell falls within a range greater than or equal to the first value and less than or equal to the second value.

20. In claim 19, A battery system, wherein the SOC deviation threshold for BMA balancing is set equal to the first value.

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