Battery management system, battery device, and balancing method

Abstract

This battery management system calculates a state of charge (SOC) of each battery cell, calculates a cell balancing time of each battery cell on the basis of information including a self-discharge rate of a corresponding battery cell and the SOC of the corresponding battery cell, and performs cell balancing of each battery cell on the basis of the cell balancing time of the corresponding battery cell.

Description

Battery management system, battery device, and balancing method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0009278 dated January 22, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] The disclosure relates to a battery management system, a battery device, and a balancing method.

[0004] Electric or hybrid vehicles are vehicles that generate power by driving a motor primarily using a battery as a power source, and active research is being conducted on them as an alternative capable of solving the pollution and energy problems associated with internal combustion engine vehicles. In addition, batteries are used in various external devices other than vehicles.

[0005] Multiple battery cells are connected in series within a battery, and voltage deviations between these cells can lead to over-discharge or over-charge, thereby reducing the cell's lifespan. To mitigate these voltage deviations, a cell balancing circuit is designed within the battery management system. The battery management system calculates the state of charge (SOC) of each battery cell and, based on the SOC, can calculate the discharge amount (i.e., balancing time) of each battery cell to reduce the deviation between cells. However, due to differences in the self-discharge rates between battery cells, deviations between cells may still exist even after balancing is complete.

[0006] In some embodiments, a battery management system, a battery device, and a balancing method capable of performing cell balancing in consideration of a self-discharge rate may be provided.

[0007] According to some embodiments, a method for balancing a plurality of battery cells in a battery management system may include the steps of calculating the SOC of each battery cell, calculating the cell balancing time of each battery cell based on information including the self-discharge rate of the corresponding battery cell and the SOC of the corresponding battery cell, and performing cell balancing of each battery cell based on the cell balancing time of the corresponding battery cell.

[0008] A battery device according to some embodiment may include a plurality of battery cells and a battery management system for managing the plurality of battery cells. The battery management system may calculate the SOC of the plurality of battery cells, calculate the cell balancing time of the target battery cell based on information including the self-discharge rate of the target battery cell among the plurality of battery cells and the SOC of the target battery cell, and perform cell balancing of the target battery cell based on the cell balancing time of the target battery cell.

[0009] According to some embodiments, a program may be provided that is executed by a processor of a battery device and stored on a computer-readable recording medium. The program may enable the processor to perform the steps of calculating the SOC of each battery cell, calculating the cell balancing time of each battery cell based on information including the self-discharge rate of the corresponding battery cell and the SOC of the corresponding battery cell, and performing cell balancing of each battery cell based on the cell balancing time of the corresponding battery cell.

[0010] FIG. 1 is a block diagram showing a battery device according to some embodiment.

[0011] FIG. 2 is a flowchart illustrating a balancing method of a battery management system according to a certain embodiment.

[0012] FIG. 3 is a flowchart illustrating a method for calculating the self-discharge rate of a battery management system according to a certain embodiment.

[0013] FIG. 4 is a diagram illustrating a method for calculating the self-discharge rate of a battery management system according to a certain embodiment.

[0014] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0015] When it is stated that a component is "connected" to another component, it should be understood that it may be directly connected to that other component, or that there may be other components in between. On the other hand, when it is stated that a component is "directly connected" to another component, it should be understood that there are no other components in between.

[0016] Expressions written in the singular in the description below may be interpreted as singular or plural unless explicit expressions such as "one" or "singular" are used.

[0017] In the flowchart described with reference to the drawings, the order of operations may be changed, multiple operations may be merged or some operations may be divided, and specific operations may not be performed.

[0018] FIG. 1 is a block diagram showing a battery device according to some embodiment.

[0019] Referring to FIG. 1, the battery device (100) may include a battery module (110), a battery management system (BMS) (120), and switches (131, 132).

[0020] The battery device (100) may have a structure that allows it to be electrically connected to an external device through a positive link terminal (P+) and a negative link terminal (P-). In some embodiments, if the external device is a load, the battery device (100) may be discharged by operating as a power source that supplies power to the load. If the external device is a charger, the battery device (100) may be charged by receiving external power through the charger. In some embodiments, the external device operating as a load may be, for example, an electronic device, a means of transportation, or an energy storage system (ESS), and the means of transportation may be, for example, a vehicle such as an electric vehicle, a hybrid vehicle, or smart mobility. The battery device (100) may be a battery pack.

[0021] A battery module (110) may include a plurality of battery cells (111). In some embodiments, the plurality of battery cells (111) may be connected in series. In some embodiments, a battery device (100) may include a plurality of battery modules (110). Each of the plurality of battery cells (111) of the battery module (110) may be connected to a battery management system (120) via wiring.

[0022] Switch (131) may be connected between the positive terminal and the positive link terminal (P+) of the battery module (110), and switch (132) may be connected between the negative terminal and the negative link terminal (P-) of the battery module (110). Switches (131, 132) may be controlled by a battery management system (120) to control the connection between the battery device (100) and an external device. In some embodiments, switches (131, 132) may each include a contactor including a relay. In some embodiments, switches (131, 132) may each include an electrical switch such as a transistor. In some embodiments, the battery device (100) may further include a driving circuit (not shown) that drives switches (131, 132) in response to a control signal from the battery management system (120).

[0023] The battery management system (120) can collect and analyze information about the battery cell (111) to control the charging and discharging, cell balancing, protection operations, etc. of the battery cell (111). The battery management system (120) may include a balancing circuit (121), a battery monitoring circuit (122), and a processor (123). In some embodiments, the battery monitoring circuit (122) and the processor (123) may operate as control circuits that control the balancing circuit (121).

[0024] A battery monitoring circuit (122) can be connected to each of the plurality of battery cells (111) included in the battery module (110) via wiring to monitor the state (e.g., cell voltage) of the battery cells (111). In some embodiments, the battery monitoring circuit (122) may include a plurality of battery monitoring circuits (122) corresponding to each of the plurality of battery modules (110). In some embodiments, one battery monitoring circuit (122) may correspond to two or more battery modules (110), or two or more battery monitoring circuits (122) may correspond to one battery module (110). In some embodiments, the battery monitoring circuit (122) may be provided as an integrated circuit (IC), and the battery monitoring circuit (122) provided as an integrated circuit is referred to as a battery monitoring IC (BMIC).

[0025] The processor (123) receives monitoring information from the battery monitoring circuit (122) and can control the operation of the battery monitoring circuit (122). The processor (123) can control the operation of the switches (131, 132). The processor (123) is a processing circuitry, and may be, for example, a microcontroller unit (MCU).

[0026] The processor (123) can obtain the SOC of each battery cell (111) based on information provided by the battery monitoring circuit (122). The processor (123) can calculate the self-discharge rate of each battery cell (111) and calculate the cell balancing time of the battery cell (111) based on the self-discharge rate and SOC of each battery cell (111). The balancing circuit (121) can balance the battery cell (111) during the cell balancing time of each battery cell (111).

[0027] FIG. 2 is a flowchart illustrating a balancing method of a battery management system according to a certain embodiment.

[0028] Referring to FIG. 2, the battery management system can calculate the SOC of each battery cell (S220). In some embodiments, the battery management system can calculate the SOC of each battery cell when waking up from sleep mode (S210) (S220). In some embodiments, the battery management system can calculate the SOC of the corresponding battery cell based on the voltage of each battery cell provided by the battery monitoring circuit (122). In this case, the voltage of each battery cell may be the open circuit voltage (OCV). For example, the battery management system can calculate the SOC of the corresponding battery cell by applying the voltage of each battery cell to the correlation between the OCV and the SOC.

[0029] The battery management system can obtain the self-discharge rate of each battery cell (S230). The self-discharge rate indicates the amount of change in SOC per hour [%] due to the self-discharge of the battery cell, and the unit may be % / s, % / m, or % / h.

[0030] The battery management system can calculate the cell balancing time of a battery cell based on the SOC and self-discharge rate of each battery cell (S240). In some embodiments, the battery management system determines the minimum SOC among the SOCs of a plurality of battery cells and can calculate the cell balancing time of a target battery cell based on the difference between the SOC of the target battery cell and the minimum SOC, the balancing discharge rate, and the self-discharge rate of the target battery cell (S240). In some embodiments, the balancing discharge rate is a value set for cell balancing in the battery management system and can represent the amount of SOC reduced per hour [%].

[0031] In some embodiments, the battery management system may determine the cell balancing time of a battery cell by dividing the difference between the SOC and the minimum SOC of each battery cell by the sum of the balancing discharge rate and the self-discharge rate of the battery cell (S240).

[0032] The battery management system can perform balancing for each battery cell during the cell balancing time of the corresponding battery cell (S250).

[0033] As explained above, the battery management system can balance the battery cells during a cell balancing time that takes into account the self-discharge rate of each battery cell, so the deviation between battery cells after balancing can be minimized.

[0034] FIG. 3 is a flowchart showing a method for calculating the self-discharge rate of a battery management system according to a certain embodiment, and FIG. 4 is a diagram explaining a method for calculating the self-discharge rate of a battery management system according to a certain embodiment.

[0035] Referring to FIG. 3, when the output of the battery device is not required, the battery management system may enter sleep mode (S310). For example, when a vehicle equipped with a battery device is parked, the battery management system may enter sleep mode.

[0036] The battery management system enters sleep mode and wakes up at a point in time (hereinafter referred to as "first point in time") (t1) after a first predetermined time (T1) has elapsed (S320), and can measure the voltage (V1) of each battery cell at the time of wake-up (S330). Therefore, the time at which the voltage (V1) of each battery cell is measured may be approximately the same as the first point in time (t1). After measuring the voltage (V1) of each battery cell (S330), the battery management system may enter sleep mode again (S340). In some embodiments, the first point in time (t1) may be the time after the battery management system has entered sleep mode and the battery cell has stabilized.

[0037] The battery management system wakes up again at a point in time (hereinafter referred to as "second point in time") (t2) after a second predetermined time (T2) has elapsed from the wake point (first point in time) (t1) (S350), and can measure the voltage (V2) of each battery cell at the wake point (S360). Therefore, the time at which the voltage (V2) of each battery cell is measured may be approximately the same as the second point in time (t2). In some embodiments, the battery management system may periodically wake up after entering sleep mode, and the first point in time and the second point in time may be the time at which the system periodically wakes up.

[0038] The battery management system can calculate the self-discharge rate of each battery cell based on each battery cell voltage (V1) measured at a first time point (t1), each battery cell voltage (V2) measured at a second time point (t2), and a second predetermined time (T2) (S370). In some embodiments, the battery management system can obtain the SOC of the target battery cell at the first time point (t1) based on the target battery cell voltage (V1) measured at the first time point (t1), and obtain the SOC of the target battery cell at the second time point (t2) based on the target battery cell voltage (V2) measured at the second time point (t2). Since the voltage of the battery cell measured at the wake-up time corresponds to the OCV, the battery management system can obtain the SOC of the target battery cell by applying the voltage of the target battery cell to the correlation between the OCV and the SOC. In some embodiments, the battery management system can calculate the self-discharge rate of each battery cell by dividing the difference between the SOC at a first time point (t1) and the SOC at a second time point (t2) for each battery cell, as shown in Equation 1, by the time difference (t2-t1) between the first time point (t1) and the second time point (t2), i.e., the second predetermined time (T2). That is, the battery management system can calculate the self-discharge rate as the amount of change in SOC per hour while the battery management system is in sleep mode (i.e., while there is no output of the battery cell).

[0039]

[0040] In mathematical formula 1, SDR represents the self-discharge rate, SOC(t1) represents the SOC at the first time point (t1), and SOC(t2) represents the SOC at the second time point (t2).

[0041] In some embodiments, the battery management system may store the calculated self-discharge rate of each battery cell and provide the stored self-discharge rate during cell balancing. In some embodiments, the battery management system may periodically calculate the self-discharge rate of each battery cell.

[0042] As explained above, the battery management system calculates the self-discharge rate based on the change in SOC per hour when the battery cell is idle, and since the self-discharge rate can be reflected in the cell balancing time, the deviation between battery cells after balancing can be minimized.

[0043] In some embodiments, a processor of a battery management system (e.g., 123 in FIG. 1) may perform operations on a program (i.e., instructions) for executing the balancing method or self-discharge rate calculation method described above. For the operations of the processor (123), the program for executing the balancing method or self-discharge rate calculation method may be loaded into memory. Such memory may be built into the processor (123) or provided outside the processor (123). When loaded into memory, the program may include instructions that cause the processor (123) to perform the balancing method or self-discharge rate calculation method. That is, the processor may perform operations for the balancing method or self-discharge rate calculation method by executing the instructions of the program. In some embodiments, the program may be stored on a computer-readable storage medium.

[0044] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. A method for balancing multiple battery cells in a battery management system, A step of calculating the state of charge (SOC) of each battery cell, A step of calculating the cell balancing time of each battery cell based on information including the self-discharge rate of the corresponding battery cell and the SOC of the corresponding battery cell, and A step of performing cell balancing of each battery cell based on the cell balancing time of the corresponding battery cell. A balancing method including 2. In Paragraph 1, A balancing method further comprising the step of calculating the self-discharge rate of each battery cell based on the hourly change in SOC of the corresponding battery cell when the battery management system enters sleep mode.

3. In Paragraph 1, A step of waking up the battery management system that has entered sleep mode at a first point in time and measuring the first voltage of each battery cell, A step of putting the battery management system back into sleep mode after measuring the first voltage of each battery cell, The step of waking up the battery management system at a second point in time after the first point in time and measuring the second voltage of each battery cell, and A step of calculating the self-discharge rate of each battery cell based on the SOC based on the first voltage of the corresponding battery cell and the SOC based on the second voltage of the corresponding battery cell. A balancing method that further includes 4. In Paragraph 3, A balancing method comprising the step of calculating the self-discharge rate, wherein the value obtained by dividing the difference between the SOC based on the first voltage and the SOC based on the second voltage by the time difference between the second time point and the first time point is calculated as the self-discharge rate.

5. In Paragraph 1, The above information further includes the balancing discharge rate, and The step of calculating the cell balancing time includes the step of calculating the cell balancing time of each battery cell by dividing the value obtained by subtracting the minimum SOC among the SOCs of the plurality of battery cells from the SOC of the corresponding battery cell by the sum of the balancing discharge rate and the corresponding self-discharge rate. Balancing method.

6. Multiple battery cells, and It includes a battery management system that manages the plurality of battery cells mentioned above, The above battery management system is, Calculate the state of charge (SOC) of the above plurality of battery cells, and Calculate the cell balancing time of the target battery cell based on information including the self-discharge rate of the target battery cell among the plurality of battery cells and the SOC of the target battery cell, and Cell balancing of the target battery cell is performed based on the cell balancing time of the target battery cell. Battery device.

7. In Paragraph 6, The above battery management system The above battery management system calculates the hourly change in SOC of the target battery cell while in a sleep mode state, and Calculating the self-discharge rate of the target battery cell based on the above hourly SOC change amount Battery device.

8. In Paragraph 6, The above battery management system At a first point in time, wake up from sleep mode, and measure the first voltage of the target battery cell, After measuring the first voltage of the above target battery cell, enter the above sleep mode, and At a second point in time after the first point in time above, wake up from the sleep mode and measure the second voltage of the target battery cell, and Calculating the self-discharge rate of the target battery cell based on the SOC based on the first voltage and the SOC based on the second voltage Battery device.

9. In Paragraph 8, The battery device, wherein the battery management system calculates the self-discharge rate by dividing the difference between the SOC based on the first voltage and the SOC based on the second voltage by the time difference between the second time point and the first time point.

10. In Paragraph 6, The above information further includes the balancing discharge rate, and The battery management system comprises the step of calculating the cell balancing time of the target battery cell by dividing the value obtained by subtracting the minimum SOC among the SOCs of the plurality of battery cells from the SOC of the target battery cell by the sum of the balancing discharge rate and the self-discharge rate. Battery device.

11. A program that is executed by a processor of a battery device and stored on a computer-readable recording medium, The above program is the above processor, A step of calculating the state of charge (SOC) of each battery cell, A step of calculating the cell balancing time of each battery cell based on information including the self-discharge rate of the corresponding battery cell and the SOC of the corresponding battery cell, and A step of performing cell balancing of each battery cell based on the cell balancing time of the corresponding battery cell. A program that causes to execute.

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