Cell balancing method for battery pack and battery pack

Abstract

The present invention relates to a cell balancing method for a battery pack, and a battery pack. The cell balancing method for a battery pack according to an embodiment of the present invention is performed by a processor of a battery management unit provided in a battery pack, and comprises: a step for collecting monitoring information, including the current, voltage, and temperature of a battery cell, from a plurality of battery cells included in the battery pack; a step for analyzing the state of the battery cells on the basis of the monitoring information to determine whether the battery cells satisfy a cell balancing condition; and a step for performing cell balancing of the battery cells if the battery cells satisfy the cell balancing condition.

Description

Cell balancing method of a battery pack and battery pack

[0001] The present invention relates to a cell balancing method for a battery pack and a battery pack.

[0002] Battery packs, particularly lithium-ion battery packs, are widely used in various fields such as electric vehicles, portable electronic devices, and large-scale energy storage systems. These battery packs consist of multiple battery cells, and voltage imbalances in each cell can have a significant impact on the performance and lifespan of the entire battery pack. Generally, cell balancing has been performed when the voltage difference between battery cells exceeds a certain standard. However, this cell balancing method does not comprehensively consider the battery's voltage, temperature, current, and the capacity required for balancing, and may be an insufficient measure in terms of efficiency and safety.

[0003] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0004] The present invention aims to provide more sophisticated and systematic cell balancing conditions to improve the performance and safety of a battery pack.

[0005] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0006] A cell balancing method for a battery pack according to one embodiment of the present invention is a cell balancing method performed by a processor of a battery management unit provided in the battery pack, and may include the steps of: collecting monitoring information including current, voltage, and temperature of a battery cell from a plurality of battery cells included in the battery pack; analyzing the state of the battery cell based on the monitoring information to determine whether the battery cell satisfies cell balancing conditions; and performing cell balancing of the battery cell as the battery cell satisfies cell balancing conditions.

[0007] A battery pack according to one embodiment of the present invention includes a battery management unit having a plurality of battery cells and at least one processor that monitors the plurality of battery cells and performs cell balancing. The at least one processor may be configured to collect monitoring information including the current, voltage, and temperature of the battery cells from the plurality of battery cells, analyze the state of the battery cells based on the monitoring information, determine whether the battery cells satisfy cell balancing conditions, and perform cell balancing of the battery cells as the battery cells satisfy cell balancing conditions.

[0008] In addition to this, other methods for implementing the present invention, other systems, and computer-readable recording media storing a computer program for executing said methods may be further provided.

[0009] Other aspects, features, and advantages other than those described above will become clear from the following drawings, claims, and detailed description of the invention.

[0010] According to the present invention, by performing balancing of battery cells based on a plurality of cell balancing conditions and managing the state of each battery cell more precisely, imbalance between battery cells can be minimized and the lifespan of the entire battery pack can be extended.

[0011] In addition, by performing cell balancing only when multiple cell balancing conditions are met, energy waste can be reduced and the energy usage efficiency of the entire battery pack can be increased.

[0012] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0013] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0014] FIG. 1 schematically illustrates a battery pack according to one embodiment of the present invention.

[0015] FIG. 2 illustrates the configuration of a battery management unit provided in a battery pack according to one embodiment of the present invention.

[0016] FIGS. 3 and 4 are flowcharts for explaining a cell balancing method according to an embodiment of the present invention.

[0017] FIGS. 5A and 5B are tables showing the results of a test on whether cell balancing is performed according to temperature in accordance with an embodiment of the present invention.

[0018] FIG. 6 is a flowchart illustrating a cell balancing method according to another embodiment of the present invention.

[0019] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor may appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention; thus, various equivalents and modifications that can replace them may exist at the time of filing this application. Furthermore, as used in this specification, "comprise" or "include" and / or "comprising" or "including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups. In addition, when describing embodiments of the present invention, "may" and "may be" may include "one or more embodiments of the present invention."

[0020] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0021] The statement that two subjects of comparison are "identical" means that they are "substantially identical." Therefore, substantial identity may include deviations considered low in the industry, for example, deviations within 5%. Additionally, the statement that a parameter is uniform in a given area may mean that it is uniform from an average perspective.

[0022] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0023] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0024] The fact that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0025] Furthermore, where it is stated that one component is "connected," "coupled," or "connected" to another component, it should be understood that while said components may be directly connected or connected to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "connected" through another component. Additionally, when it is stated that a part is electrically coupled with another part, this includes not only cases where they are directly connected but also cases where they are connected with another component in between.

[0026] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise. That is, "and / or" includes any combination or any combination of the enumerated items. "C to D" means C or more and D or less, unless specifically stated otherwise.

[0027] FIG. 1 schematically illustrates a battery pack according to one embodiment of the present invention, and FIG. 2 illustrates the configuration of a battery management unit provided in a battery pack according to one embodiment of the present invention.

[0028] Referring to FIGS. 1 and 2, the battery pack (1) according to the present embodiment may include pack terminals (Pack+, Pack-), a battery module (100), a battery management system (BMS) (200), a connector (300), and a fuse (F1).

[0029] The battery module (100) may include a plurality of battery cells (C) connected in series or in parallel with each other. The battery cells (C) may include secondary batteries other than rechargeable lead-acid batteries. For example, the battery cells (C) may include nickel-cadmium batteries, nickel metal hydride batteries (NiMH), lithium-ion batteries, and lithium polymer batteries.

[0030] The battery module (100) can be connected to an external charging device (not shown) or a load (not shown) through pack terminals (Pack+, Pack-). The battery module (100) can receive charging current from the charging device connected through the pack terminals (Pack+, Pack-). Additionally, the battery module (100) can supply discharge current to the load connected through the pack terminals (Pack+, Pack-). In this embodiment, the path through which charging current or discharge current flows between the battery module (100) and the pack terminals (Pack+, Pack-) can be named a 'high current path'.

[0031] The fuse (F1) is connected to the high-current path between the battery module (100) and the pack terminals (Pack+, Pack-) and can block the high-current path.

[0032] The battery management unit (200) can control the overall operation of the battery pack (1). The battery management unit (200) is connected to the battery module (100) and can control at least one operation of charging and discharging of the battery module (100). To protect the battery module (100), the battery management unit (200) can perform an overcharge protection function, an over-discharge protection function, an overcurrent protection function, an overvoltage protection function, an overheating protection function, etc. To this end, the battery management unit (200) monitors the voltage, current, temperature, remaining power amount, lifespan, charge status, etc., for each of the plurality of battery cells (C) included in the battery module (100), and can apply necessary protection measures using the monitoring results. In addition, the battery management unit (200) can perform a cell balancing function, and specific cell balancing methods will be explained in detail in FIGS. 3 to 5.

[0033] In this embodiment, the battery management unit (200) may include a charging control switch (SW1), a discharging control switch (SW2), a current sensing resistor (R1), and a processor (210).

[0034] Meanwhile, the components shown in FIG. 2 are not essential, so the battery management unit (200) may be implemented to include more or fewer components than shown in FIG. 2.

[0035] The charging control switch (SW1) is turned on / off by a control signal input from the processor (210), which can block or allow the flow of charging current supplied from an external charging device to the battery module (100) through a high-current path. When the charging control switch (SW1) is turned on, the charging control switch (SW1) conducts, allowing charging current to flow from the charging device to the battery module (100) through the high-current path. On the other hand, when the charging control switch (SW1) is turned off, the flow of charging current flowing through the high-current path between the charging device and the battery module (100) can be blocked.

[0036] For example, in FIG. 1, the charging control switch (SW1) may be connected to a high-current path between the positive terminal (BAT+) and the pack terminal (Pack+) of the battery module (100). However, the present invention is not limited thereto, and according to other embodiments, the charging control switch (SW1) may be connected between the negative terminal (BAT-) and the pack terminal (Pack-) of the battery module (100).

[0037] The discharge control switch (SW2) is turned on / off by a control signal input from the processor (210), which can block or allow the flow of discharge current supplied from the battery module (100) to an external load through a high-current path. When the discharge control switch (SW2) is turned on, the discharge control switch (SW2) conducts, allowing discharge current to flow from the battery module (100) to the load through the high-current path. On the other hand, when the discharge control switch (SW2) is turned off, the flow of discharge current flowing through the high-current path between the battery module (100) and the load can be blocked.

[0038] For example, in FIG. 1, the discharge control switch (SW2) may be connected to a high-current path between the positive terminal (BAT+) and the pack terminal (Pack+) of the battery module (100). However, the present invention is not limited thereto, and according to other embodiments, the discharge control switch (SW2) may be connected between the negative terminal (BAT-) and the pack terminal (Pack-) of the battery module (100).

[0039] The charge control switch (SW1) and the discharge control switch (SW2) may be field effect transistors (FETs).

[0040] A current sensing resistor (R1) is connected in series to a high-current path and can be used to measure the current flowing through the high-current path (e.g., charging current). Taking FIG. 1 as an example, the current sensing resistor (R1) can be connected between the negative terminal (BAT-) and the pack terminal (Pack-) of the battery module (100). However, the present invention is not limited thereto, and according to other embodiments, the current sensing resistor (R1) can be connected to a high-current path between the positive terminal (BAT+) and the pack terminal (Pack+) of the battery module (100).

[0041] The processor (210) can control the overall operation of the battery management unit (200). The processor (210) can control the on / off of the charging control switch (SW1) or the discharging control switch (SW2) by outputting a control signal to the charging control switch (SW1) or the discharging control switch (SW2).

[0042] The processor (210) can control the state of the battery module (100) by collecting measurement results of monitoring information including at least one of the current, voltage, and temperature of each of the plurality of battery cells (C) included in the battery module (100).

[0043] The processor (210) may be connected to a current detection circuit (not shown) that is electrically connected to both ends of a current sensing resistor (R1) through current measurement terminals (IS0, IS1). The processor (210) may collect the current measurement results flowing through the current sensing resistor (R1) through the current detection circuit. The current sensing resistor (R1) may be located on a high-current path between the battery module (100) and one of the pack terminals (Pack-). Thus, the processor (210) may collect the current measurement results flowing through the high-current path (e.g., charging current) by collecting the current measurement results flowing through the current sensing resistor (R1) through the current detection circuit.

[0044] The processor (210) may be connected to a voltage detection circuit (not shown) that is connected to each battery cell (C) constituting the battery module (100) through a connector (300). The processor (210) may collect the detection result of the voltage of at least one battery cell (C) constituting the battery module (100) through the voltage detection circuit. Additionally, the processor (210) may collect the voltage detection result of both ends of the battery module (100) through the voltage detection circuit.

[0045] The processor (210) may be connected to a temperature detection circuit (not shown) that is connected to each battery cell (C) constituting the battery module (100) via a connector (300). In this embodiment, the temperature detection circuit may include a thermistor. The processor (210) may collect the temperature detection results of at least one battery cell (C) constituting the battery module (100) through the temperature detection circuit. Additionally, the processor (210) may collect the temperature detection results of the battery pack (1) surrounding the battery via the temperature detection circuit.

[0046] The processor (210) can analyze the state of the battery cell (C) based on monitoring information including at least one of the current, voltage, and temperature of the battery cell (C) and determine whether the battery cell (C) satisfies cell balancing conditions.

[0047] In this embodiment, the cell balancing conditions may include first to fourth cell balancing conditions. The first cell balancing condition and the second cell balancing condition may be related to the amount of change in cell voltage for the battery cell (C). The third cell balancing condition may be related to the temperature of the battery cell (C). The fourth cell balancing condition may be related to the voltage of the entire battery pack (1), that is, the total voltage of the battery module (100). The cell balancing conditions will be described below.

[0048] The processor (210) can perform cell balancing of the battery cell (C) as the battery cell (C) satisfies the cell balancing condition. In this embodiment, the processor (210) can perform cell balancing of the battery cell (C) only when all of the first to fourth cell balancing conditions are satisfied. That is, the processor (210) may not perform cell balancing of the battery cell (C) if any of the first to fourth cell balancing conditions are not satisfied.

[0049] In this embodiment, the cell balancing method may include at least one of passive cell balancing and active cell balancing. Depending on the use and design specifications of the battery pack (1) used, one of passive cell balancing and active cell balancing may be selected.

[0050] Manual cell balancing may include a method of monitoring the voltage of each battery cell (C) and dissipating excess power as heat through a resistor from a cell that has risen above a specific voltage. This method is relatively simple and may be inexpensive to implement. However, this method has the disadvantage of low energy efficiency because it consumes energy as heat. In the present embodiment, manual cell balancing may be controlled by a processor (210). The processor (210) may collect monitoring information and perform cell balancing when all of the first to fourth cell balancing conditions are satisfied. When a battery cell (C) requiring cell balancing is detected, the processor (210) may adjust the voltage through a balancing resistor connected to the battery cell (C).

[0051] Active cell balancing may include a method of directly transferring energy from a high-voltage cell to a low-voltage cell. This method may transfer energy using an inductor (not shown), a capacitor (not shown), or a DC-DC converter (not shown). Active cell balancing may provide advantages such as low energy loss, fast balancing speed, and improved efficiency of the entire battery pack. In this embodiment, active cell balancing may be controlled by a processor (210). The processor (210) may collect monitoring information and, when all of the first cell balancing conditions to the fourth cell balancing conditions are satisfied, adjust the energy transfer to maintain a uniform voltage between the battery cells (C).

[0052] In this way, by performing battery cell balancing based on the first to fourth cell balancing conditions and managing the state of each battery cell more precisely, imbalance between battery cells can be minimized and the lifespan of the entire battery pack can be extended. In addition, by performing cell balancing only when the first to fourth cell balancing conditions are satisfied, energy waste can be reduced and the energy usage efficiency of the entire battery pack can be increased.

[0053] Meanwhile, the processor (210) can control the operation of the entire battery pack (1). Here, 'processor' may refer to a data processing device embedded in hardware having a physically structured circuit to perform functions expressed by code or instructions included in a program, for example. Examples of such data processing devices embedded in hardware may include microprocessors, central processing units, processor cores, multiprocessors, ASICs, FPGAs, etc., but the scope of the present invention is not limited thereto.

[0054] In the present embodiment, the battery management unit (200) may further include a memory (not shown). The memory is operably connected to the processor (210) and can store at least one code associated with an operation performed by the processor (210).

[0055] Additionally, the memory may perform the function of temporarily or permanently storing data processed by the processor (210). Here, the memory may include a magnetic storage medium or a flash storage medium, but the scope of the present invention is not limited thereto. Such memory may include internal memory and / or external memory, and may include volatile memory such as DRAM, SRAM, or SDRAM, non-volatile memory such as OTPROM, PROM, EPROM, EEPROM, mask ROM, flash ROM, NAND flash memory, or NOR flash memory, flash drives such as SSD, CF card, SD card, Micro-SD card, Mini-SD card, xD card, or Memory Stick, or storage devices such as HDD.

[0056] FIGS. 3 and 4 are flowcharts for explaining a cell balancing method according to an embodiment of the present invention. In the following description, parts that overlap with the description of FIGS. 1 and 2 will be omitted. The cell balancing method according to the present embodiment will be explained under the assumption that a battery management unit (200) provided in a battery pack (1) performs the task at a processor (210) with the help of surrounding components.

[0057] Referring to FIGS. 3 and FIGS. 4, in step S310, the processor (210) can collect monitoring information including at least one of the current, voltage, and temperature of a battery cell (C) from a plurality of battery cells included in the battery pack (1).

[0058] In step S320, the processor (210) can analyze the state of the battery cell (C) based on monitoring information and determine whether the battery cell (C) satisfies the cell balancing condition.

[0059] In step S321, the processor (210) can determine whether the first cell balancing condition is satisfied by comparing the first cell voltage change amounts and the first voltage reference values ​​calculated based on monitoring information after at least one termination of charging and discharging of the battery cell (C).

[0060] The processor (210) calculates the first-1 cell voltage change amount based on monitoring information after the battery cell (C) finishes charging ( ) and, the internal resistance (IR, of the battery cell (C) ) and charging current( The 1-1 voltage reference value calculated based on ) It can be determined whether the 1-1 cell balancing condition is satisfied through comparison of ).

[0061] In this embodiment, the 1-1 cell voltage change amount may include the difference in cell voltage measured at preset time intervals (e.g., 3 minutes) from the start to the end of charging of the battery cell (C). Additionally, in this embodiment, the 1-1 voltage reference value is the preset internal resistance of the battery cell (C). ) and preset charging current ( ) and, tolerance ( It may be a value calculated and stored by ).

[0062] The processor (210) has a first-1 cell voltage change amount ( ) is the 1-1 voltage reference value ( As it is less than ) it can be determined that the 1-1 cell balancing condition is satisfied.

[0063] When charging the battery cell (C), the cell voltage increases, but when charging is terminated, the cell voltage can decrease by the polarization voltage. Here, the polarization resistance is the internal resistance of the battery cell (C). ) and charging current( It can be calculated as the product of ). Accordingly, the 1-1 cell voltage change amount It can be expressed as.

[0064] Meanwhile, the internal resistance of the battery cell (C) ) can change depending on the temperature. As the temperature rises, the internal resistance of the battery cell (C) ( ) decreases, and as the temperature drops, the internal resistance of the battery cell (C) ( ) can increase.

[0065] 1-1 Voltage Reference Value ( ) can be pre-set as the amount of cell voltage reduction expected at the end of charging. The first-1 cell voltage change amount ( calculated by the processor (210) ) is the internal resistance of the battery cell (C) that varies with temperature ( ) can be reflected. The processor (210) has a first-1 cell voltage change amount ( ) is the 1-1 voltage reference value ( As it is less than ) it can be determined that the cell voltage is in a stable state and that the 1-1 cell balancing condition is satisfied.

[0066] However, the processor (210) has a first-1 cell voltage change amount ( ) is the 1-1 voltage reference value ( If it exceeds ), it can be determined that the cell voltage is in an unstable state and that the 1-1 cell balancing condition is not satisfied.

[0067] The processor (210) calculates the first-second cell voltage change amount based on monitoring information after the discharge of the battery cell (C) ends ( ) and, the internal resistance (IR, of the battery cell (C) ) and discharge current( 1st-2nd voltage reference value calculated based on ) It can be determined whether the 1st and 2nd cell balancing conditions are satisfied through comparison of ).

[0068] In this embodiment, the first-2 cell voltage change amount may include the difference in cell voltage measured at a preset time interval (e.g., 3 minutes) from the start to the end of discharge of the battery cell (C). In addition, in this embodiment, the first-2 voltage reference value is the preset internal resistance of the battery cell (C). ) and preset discharge current ( ) and, tolerance ( It may be a value calculated and stored by ).

[0069] The processor (210) has a first-second cell voltage change amount ( ) is the 1st-2nd voltage reference value( As such, it can be determined that the 1st and 2nd cell balancing conditions are satisfied.

[0070] When discharging a battery cell (C), the cell voltage decreases, but when discharging is terminated, the cell voltage can increase by the polarization voltage. Here, the polarization resistance is the internal resistance of the battery cell (C). ) and discharge current( It can be calculated as the product of ). Accordingly, the change in the first and second cell voltages It can be expressed as.

[0071] Meanwhile, the internal resistance of the battery cell (C) ) can change depending on the temperature. As the temperature rises, the internal resistance of the battery cell (C) ( ) decreases, and as the temperature drops, the internal resistance of the battery cell (C) ( ) can increase.

[0072] 1st-2nd voltage reference value ( ) can be pre-set as the amount of cell voltage reduction expected at the end of discharge. The first-second cell voltage change amount ( calculated by the processor (210) ) is the internal resistance of the battery cell (C) that varies with temperature ( ) can be reflected. The processor (210) has a first-second cell voltage change amount ( ) is the 1st-2nd voltage reference value( Based on the above, it can be determined that the cell voltage is in a stable state and that the 1-1 cell balancing condition is satisfied.

[0073] However, the processor (210) has a first-second cell voltage change amount ( ) is the 1st-2nd voltage reference value( If it is less than ), it can be determined that the cell voltage is in an unstable state and that the first-2 cell balancing conditions are not satisfied.

[0074] In step S322, the processor (210) determines the second cell voltage change amount relative to a first reference time (e.g., 3 minutes) calculated based on monitoring information, when at least one of the charging current and the discharging current applied to the battery cell (C) is less than a first current reference value (e.g., 0.1A). It can be determined whether the second cell balancing condition is satisfied by comparing the ) and the second voltage reference value (e.g., 3mV).

[0075] In the present embodiment, the statement that at least one of the charging current and the discharging current applied to the battery cell (C) is less than a first current reference value (e.g., 0.1A) may include the battery cell (C) not being in a charging or discharging state. For example, it may include a state in which the battery cell (C) has completed charging or discharging and a certain amount of time has elapsed.

[0076] The processor (210) has a second cell voltage change amount (e.g., 3 minutes) relative to a first reference time (e.g., 3 minutes). It can be determined that the second cell balancing condition is satisfied as ) is less than or equal to the second voltage reference value (e.g., 3mV).

[0077] When the charging or discharging of the battery cell (C) is completed, the cell voltage may stabilize over time. A small change in cell voltage may indicate that the battery cell (C) has reached a stable state. Accordingly, the processor (210) may determine that the battery cell (C) is in a stable state and that the second cell balancing condition is satisfied, based on the fact that the change in cell voltage relative to the first reference time is less than or equal to the second voltage reference value.

[0078] However, the processor (210) has a second cell voltage change amount (e.g., 3 minutes) relative to a first reference time (e.g., 3 minutes). As ) exceeds the second voltage reference value (e.g., 3mV), it can be determined that the battery cell (C) is in an unstable state and that the second cell balancing condition is not satisfied.

[0079] In step S323, the processor (210) can determine whether the third cell balancing condition is satisfied by comparing at least one of the temperature of the battery cell and the amount of temperature change calculated based on monitoring information with temperature reference values.

[0080] The processor (210) measures the amount of temperature change of the battery cell (C) at preset time intervals (e.g., 3 minutes). It can be determined whether the 3-1 cell balancing condition is satisfied by comparing ) and the first temperature reference value (e.g., 3℃). The processor (210) determines the amount of temperature change of the battery cell (C) ( As ) is less than or equal to the first temperature reference value (e.g., 3℃), it can be determined that the 3-1 cell balancing condition is satisfied.

[0081] Change in temperature of battery cell (C) If ) exceeds a first temperature reference value (e.g., 3°C), it may become hotter or colder than other battery cells (C) inside the battery module (100). This temperature imbalance causes performance differences between battery cells (C), and even if cell balancing is performed, the imbalance in cell voltage and capacity may not be resolved. Accordingly, the processor (210) [determines] the amount of temperature change of the battery cell (C) If ) is 0 or less than the first temperature reference value (e.g., 3℃), it can be determined that cell balancing is possible.

[0082] The processor (210) is the temperature of the battery cell (C) It can be determined whether the 3-2 cell balancing condition is satisfied by comparing the temperature of the battery cell (C) with the second temperature reference value (e.g., 23℃) and the third temperature reference value (e.g., 27℃). The processor (210) determines whether the temperature of the battery cell (C) ( As ) is located between the second temperature reference value (e.g., 23℃) and the third temperature reference value (e.g., 27℃), it can be determined that the third-2 cell balancing condition is satisfied.

[0083] Temperature of the battery cell (C) If ) is below a second temperature reference value (e.g., 23℃) or exceeds a third temperature reference value (e.g., 27℃), the chemical reaction rate and properties of the battery cell (C) change, and cell balancing may not be performed accurately. Accordingly, the processor (210) [regarding] the temperature of the battery cell (C) When ) is located between the second temperature reference value (e.g., 23℃) and the third temperature reference value (e.g., 27℃), it can be determined that cell balancing is possible because the chemical reaction rate and properties of the battery cell (C) do not change.

[0084] FIGS. 5A and 5B are tables illustrating the test results regarding whether cell balancing is performed according to temperature in accordance with an embodiment of the present invention. Referring to FIG. 5A, on May 10, the temperature of an arbitrary battery cell (C) ( The cell voltage difference is shown after performing cell balancing in a state where ) exceeds the third temperature reference value (e.g., 30℃ or higher).

[0085] Referring to Fig. 5b, after 4 days have passed, on May 14, the temperature of the same battery cell (C) ( It shows the cell voltage difference measured without performing cell balancing when the third temperature reference value is exceeded (e.g., 30℃ or higher).

[0086] Comparing FIG. 5a and FIG. 5b, it can be seen that when cell balancing is performed in a state exceeding the third temperature reference value (e.g., 30°C or higher), the cell voltage difference actually increases. Therefore, the temperature of the battery cell (C) ( It is more desirable not to perform cell balancing when ) exceeds the third temperature reference value (e.g., 27℃).

[0087] In step S324, the processor (210) can determine whether the fourth cell balancing condition is satisfied by comparing the total voltage of the battery pack (1) calculated based on monitoring information with the third reference voltage value (e.g., 3.6V).

[0088] The processor (210) may determine that the fourth cell balancing condition is satisfied as the total voltage of the battery pack is greater than or equal to the third reference voltage value (e.g., 3.6V). The processor (210) may determine that the fourth cell balancing condition is not satisfied as the total voltage of the battery pack is less than the third reference voltage value (e.g., 3.6V).

[0089] The optimal operating voltage range of the battery cell (C) can generally be between 3.0V and 4.2V. An overall voltage of the battery pack (1) being above a third reference value may indicate that some battery cells (C) may have already approached or reached this upper limit. In such cases, cell balancing can be performed to prevent some battery cells (C) from reaching an overcharged state, thereby ensuring that each battery cell (C) operates within a safe and efficient range.

[0090] In step S330, the processor (210) may perform cell balancing of the battery cell (C) as the battery cell (C) satisfies the cell balancing condition. In this embodiment, the processor (210) may perform cell balancing of the battery cell (C) when all of the first cell balancing condition, the second cell balancing condition, the third cell balancing condition, and the fourth cell balancing condition are satisfied. The processor (210) may not perform cell balancing of the battery cell (C) if at least one of the first cell balancing condition, the second cell balancing condition, the third cell balancing condition, and the fourth cell balancing condition is not satisfied.

[0091] The processor (210) can calculate the required balancing capacity when all of the first cell balancing condition, the second cell balancing condition, the third cell balancing condition, and the fourth cell balancing condition are satisfied.

[0092] For example, if the difference between the maximum cell voltage and the minimum cell voltage is 100mV, depending on the characteristics of the battery cell (C), it may generally result in a capacity deviation of 10%. Accordingly, the battery cell (C) with the maximum cell voltage may require balancing for 10% of the capacity. If the capacity of the battery cell (C) is 100Ah, since balancing for 10% of the capacity is required, 10Ah of capacity must be discharged, and the processor (210) can control the battery cell (C) with the maximum cell voltage to discharge 10Ah of capacity.

[0093] FIG. 6 is a flowchart illustrating a cell balancing method according to another embodiment of the present invention. In the following description, parts that overlap with the description of FIG. 1 to FIG. 5 will be omitted. The cell balancing method according to the present embodiment will be described under the assumption that a battery management unit (200) provided in a battery pack (1) performs the task at a processor (210) with the help of surrounding components.

[0094] Referring to FIG. 6, in step S610, the processor (210) can collect monitoring information including at least one of the current, voltage, and temperature of the battery cell (C) from a plurality of battery cells included in the battery pack (1).

[0095] In step S620, the processor (210) can analyze the state of the battery cell (C) based on monitoring information and determine whether the battery cell (C) satisfies the cell balancing condition.

[0096] In step S621, the processor (210) can determine whether the first cell balancing condition is satisfied by comparing the first cell voltage change amounts and the first voltage reference values ​​calculated based on monitoring information after at least one of the charging and discharging of the battery cell has ended. In this embodiment, the first cell balancing condition may include a first-1 cell balancing condition and a first-2 cell balancing condition.

[0097] The mathematical formula that can determine whether the first cell balancing condition is satisfied is the following mathematical formula 1.

[0098]

[0099] In mathematical formula 1, cellIR represents the internal resistance of the battery cell (C), Ic represents the charging current, and 95% represents the tolerance. CellIR × Ic × 95% represents the first-1 voltage reference value, and |-△V| represents the first-1 cell voltage change amount. From this, the processor (210) can determine that the first-1 cell balancing condition is satisfied if the first-1 cell voltage change amount is less than or equal to the first-1 voltage reference value.

[0100] Meanwhile, in mathematical formula 1, Ip represents the discharge current, cellIR×Ip×95% represents the first-2 voltage reference value, and │+△V│ may be the first-2 cell voltage change amount. From this, the processor (210) can determine that the first-2 cell balancing condition is satisfied if the first-2 cell voltage change amount is greater than or equal to the first-2 voltage reference value.

[0101] In this embodiment, the processor (210) may move to step S622 if the first cell balancing condition is satisfied, and terminate if the first cell balancing condition is not satisfied.

[0102] In step S622, the processor (210) can determine whether the second cell balancing condition is satisfied by comparing the second cell voltage change amount and the second voltage reference value calculated based on monitoring information when at least one of the charging current and the discharging current applied to the battery cell is less than the first current reference value.

[0103] The mathematical formula that can determine whether the second cell balancing condition is satisfied is the following mathematical formula 2.

[0104]

[0105] In mathematical formula 2, Ic represents the charging current, Ip represents the discharging current, and △V represents the second cell voltage change amount. From this, the processor (210) can determine that the second cell balancing condition is satisfied as at least one of the charging current and the discharging current applied to the battery cell is less than the first current reference value, and the second cell voltage change amount relative to the first reference time is less than or equal to the second voltage reference value.

[0106] In this embodiment, the processor (210) may proceed to step S623 if the second cell balancing condition is satisfied, and terminate if the second cell balancing condition is not satisfied.

[0107] In step S623, the processor (210) can determine whether the third cell balancing condition is satisfied by comparing at least one of the temperature of the battery cell and the amount of temperature change calculated based on monitoring information with temperature reference values. In this embodiment, the third cell balancing condition may include the third-1 cell balancing condition and the third-2 cell balancing condition.

[0108] The mathematical formula that can determine whether the third cell balancing condition is satisfied is the following mathematical formula 3.

[0109]

[0110] In mathematical formula 3, △T represents the amount of temperature change of the battery cell (C) measured at preset time intervals, and T represents the temperature of the battery cell (C) measured at any point in time. From this, the processor (210) can determine that the 3-1 cell balancing condition is satisfied as the amount of temperature change of the battery cell (C) is less than or equal to the 1st temperature reference value, and can determine that the 3-2 cell balancing condition is satisfied as the temperature of the battery cell (C) is located between the 2nd temperature reference value and the 3rd temperature reference value.

[0111] In this embodiment, the processor (210) may move to step S624 if the third cell balancing condition is satisfied, and terminate if the third cell balancing condition is not satisfied.

[0112] In step S624, the processor (210) can determine whether the fourth cell balancing condition is satisfied by comparing the total voltage of the battery pack calculated based on monitoring information with the third reference voltage value.

[0113] The mathematical formula that can determine whether the fourth cell balancing condition is satisfied is the following mathematical formula 4.

[0114]

[0115] The processor (210) can determine that the fourth cell balancing condition is satisfied as the total voltage of the battery pack is greater than or equal to the third reference voltage value.

[0116] In this embodiment, the processor (210) may move to step S630 if the fourth cell balancing condition is satisfied, and terminate if the fourth cell balancing condition is not satisfied.

[0117] In step S630, the processor (210) can perform cell balancing of the battery cell (C) as all of the first cell balancing conditions to the fourth cell balancing conditions are satisfied.

[0118] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

1. A cell balancing method performed by a processor of a battery management unit equipped in a battery pack, wherein A step of collecting monitoring information including current, voltage, and temperature of battery cells from a plurality of battery cells included in a battery pack; A step of analyzing the state of the battery cell based on the above monitoring information to determine whether the battery cell satisfies cell balancing conditions; and A method comprising the step of performing cell balancing of the battery cell as the battery cell satisfies cell balancing conditions. Cell balancing method for a battery pack.

2. In Paragraph 1, The step of determining whether the above cell balancing condition is satisfied is, A step of determining whether a first cell balancing condition is satisfied by comparing first cell voltage change amounts and first voltage reference values ​​calculated based on the monitoring information after at least one termination of charging and discharging of the battery cell; A step of determining whether a second cell balancing condition is satisfied by comparing a second cell voltage change amount relative to a first reference time and a second voltage reference value calculated based on the monitoring information, while at least one of the charging current and the discharging current applied to the battery cell is less than a first current reference value; A step of determining whether a third cell balancing condition is satisfied by comparing at least one of the temperature and temperature change amount of the battery cell calculated based on the above monitoring information with temperature reference values; and A step comprising determining whether a fourth cell balancing condition is satisfied by comparing the total voltage of the battery pack calculated based on the above monitoring information with a third reference voltage value, Cell balancing method for a battery pack.

3. In Paragraph 2, The step of performing cell balancing of the above battery cell is, A method comprising the step of performing cell balancing of the battery cell as all of the first cell balancing condition, the second cell balancing condition, the third cell balancing condition, and the fourth cell balancing condition are satisfied. Cell balancing method for a battery pack.

4. In Paragraph 2, The step of determining whether the first cell balancing condition is satisfied is, A step of determining whether the 1-1 cell balancing condition is satisfied by comparing the 1-1 cell voltage change amount calculated based on the monitoring information after the charging of the battery cell is finished with the 1-1 voltage reference value calculated based on the internal resistance and charging current of the battery cell; and A step of determining whether the 1st-2 cell balancing condition is satisfied by comparing the 1st-2 cell voltage change amount calculated based on the monitoring information after the discharge of the battery cell with the 1st-2 voltage reference value calculated based on the internal resistance and discharge current of the battery cell. Cell balancing method for a battery pack.

5. In Paragraph 4, The step of determining whether the first cell balancing condition is satisfied is, A step of determining that the 1-1 cell balancing condition is satisfied as the 1-1 cell voltage change amount is less than or equal to the 1-1 voltage reference value; and A step of determining that the first-2 cell balancing condition is satisfied, based on the fact that the first-2 cell voltage change amount is greater than or equal to the first-2 voltage reference value, Cell balancing method for a battery pack.

6. In Paragraph 2, The step of determining whether the second cell balancing condition is satisfied is, A step of determining that the second cell balancing condition is satisfied based on the fact that the amount of change in the second cell voltage relative to the first reference time is less than or equal to the second voltage reference value, Cell balancing method for a battery pack.

7. In Paragraph 2, The step of determining whether the third cell balancing condition is satisfied is, A step of determining whether the 3-1 cell balancing condition is satisfied through a comparison of the temperature change amount of the battery cell and the first temperature reference value; and A step comprising determining whether the 3-2 cell balancing condition is satisfied through a comparison of the temperature of the battery cell, a second temperature reference value, and a third temperature reference value, Cell balancing method for a battery pack.

8. In Paragraph 7, The step of determining whether the third cell balancing condition is satisfied is, A step of determining that the 3-1 cell balancing condition is satisfied as the amount of temperature change of the battery cell is less than or equal to the first temperature reference value; and A step comprising determining that the 3-2 cell balancing condition is satisfied as the temperature of the battery cell is located between a second temperature reference value and a third temperature reference value, Cell balancing method for a battery pack.

9. In Paragraph 2, The step of determining whether the fourth cell balancing condition is satisfied is, A step comprising determining that the fourth cell balancing condition is satisfied as the total voltage of the battery pack is greater than or equal to the third reference voltage value, Cell balancing method for a battery pack.

10. A computer-readable recording medium storing a computer program for executing the method of claim 1 using a computer.

11. As a battery pack, Multiple battery cells; and It includes a battery management unit having at least one processor that monitors the plurality of battery cells and performs cell balancing, and The above-mentioned at least one processor is, Collecting monitoring information including the current, voltage, and temperature of the battery cells from the plurality of battery cells above, and Based on the above monitoring information, the state of the battery cell is analyzed to determine whether the battery cell satisfies the cell balancing condition, and Configured to perform cell balancing of the battery cell as the battery cell satisfies the cell balancing condition, Battery pack.

12. In Paragraph 11, The above-mentioned at least one processor is, In determining whether the above cell balancing conditions are satisfied, After the termination of at least one of the charging and discharging of the battery cell, determining whether the first cell balancing condition is satisfied through a comparison of the first cell voltage change amounts and first voltage reference values ​​calculated based on the monitoring information, and In a state where at least one of the charging current and the discharging current applied to the battery cell is less than a first current reference value, determining whether the second cell balancing condition is satisfied through a comparison of the second voltage change amount relative to the first reference time calculated based on the monitoring information and the second voltage reference value, and Determining whether the third cell balancing condition is satisfied by comparing at least one of the temperature and temperature change amount of the battery cell calculated based on the above monitoring information with temperature reference values, and Configured to determine whether the fourth cell balancing condition is satisfied by comparing the total voltage of the battery pack calculated based on the above monitoring information with the third reference voltage value, Battery pack.

13. In Paragraph 12, The above-mentioned at least one processor is, In performing cell balancing of the above battery cell, Configured to perform cell balancing of the battery cell by satisfying all of the above first cell balancing condition, the above second cell balancing condition, the above third cell balancing condition, and the above fourth cell balancing condition, Battery pack.

14. In Paragraph 12, The above-mentioned at least one processor is, In determining whether the first cell balancing condition is satisfied, After the charging of the battery cell is finished, it is determined whether the 1-1 cell balancing condition is satisfied by comparing the 1-1 cell voltage change amount calculated based on the monitoring information with the 1-1 voltage reduction reference value calculated based on the internal resistance and charging current of the battery cell. A method configured to determine whether the 1st-2 cell balancing condition is satisfied by comparing the 1st-2 cell voltage change amount calculated based on the monitoring information after the discharge of the battery cell with the 1st-2 voltage increase reference value calculated based on the internal resistance and discharge current of the battery cell. Battery pack.

15. In Paragraph 14, The above-mentioned at least one processor is, In determining whether the first cell balancing condition is satisfied, It is determined that the cell balancing condition is satisfied as the above 1-1 change amount is less than or equal to the above 1-1 voltage reduction reference value, and Configured to determine that the 1-2 cell balancing condition is satisfied, based on the fact that the 1-2 cell voltage change amount is greater than or equal to the 1-2 voltage increase reference value. Battery pack.

16. In Paragraph 12, The above-mentioned at least one processor is, In determining whether the second cell balancing condition is satisfied, A configuration configured to determine that the second cell balancing condition is satisfied, based on the fact that the second voltage change amount relative to the first reference time is less than or equal to the second voltage reference value. Battery pack.

17. In Paragraph 12, The above-mentioned at least one processor is, In determining whether the third cell balancing condition is satisfied, It is determined whether the 3-1 cell balancing condition is satisfied by comparing the temperature change amount of the battery cell above with the 1st temperature reference value, and A method configured to determine whether the 3-2 cell balancing condition is satisfied by comparing the temperature of the battery cell with the second temperature reference value and the third temperature reference value. Battery pack.

18. In Paragraph 17, The above-mentioned at least one processor is, In determining whether the third cell balancing condition is satisfied, It is determined that the above 3-1 cell balancing condition is satisfied as the amount of temperature change of the above battery cell is less than or equal to the first temperature reference value, and Configured to determine that the 3-2 cell balancing condition is satisfied as the temperature of the battery cell is located between the second temperature reference value and the third temperature reference value. Battery pack.

19. In Paragraph 12, The above-mentioned at least one processor is, In determining whether the fourth cell balancing condition is satisfied, Configured to determine that the fourth cell balancing condition is satisfied as the total voltage of the battery pack is greater than or equal to the third reference voltage value, Battery pack.

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