Battery management system, battery device, and method for diagnosing cell voltage measurement line

Abstract

Provided is a battery management system, wherein a battery monitoring circuit: is connected to a battery cell through a cell voltage measurement line; measures a voltage of the battery cell as a first voltage through the cell voltage measurement line in a state in which cell balancing of the battery cell is disabled; and measures the voltage of the battery cell as a second voltage through the cell voltage measurement line in a state in which the cell balancing of the battery cell is enabled. A processor diagnoses the cell voltage measurement line on the basis of the difference between the first voltage and the second voltage, and the first voltage.

Description

Battery management system, battery device and cell voltage measurement line diagnostic method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0054637, dated April 24, 2024, the entire contents of which are incorporated herein by reference.

[0003] The disclosure relates to a battery management system, a battery device and a cell voltage measurement line diagnostic method.

[0004] Electric vehicles and hybrid vehicles are primarily powered by batteries, which power the motors. Research is actively underway on these vehicles as an alternative to addressing the pollution and energy issues associated with internal combustion engines. Furthermore, batteries are used in a variety of external devices beyond vehicles.

[0005] As the maximum output required by external devices increases, more battery cells are used, requiring accurate measurement of the voltage of the battery cells (referred to as "cell voltage") for accurate diagnosis and control. Cell voltage measurement lines are used to measure cell voltage, but if there is a problem with the cell voltage measurement line, accurate cell voltage measurement is impossible.

[0006] If the difference between the cell voltage measured when the balancing current is not flowing and the cell voltage measured when the balancing current is flowing is greater than a certain voltage, it can be determined that there is a problem with the cell voltage measurement line. However, when the cell voltage is low, the balancing current is small, so the difference between the two voltages is small. Therefore, this method can only diagnose the cell voltage measurement line when the cell voltage is high, and may not be able to diagnose the cell voltage measurement line when the cell voltage is low.

[0007] In some embodiments, a battery management system, a battery device, and a cell voltage measurement line diagnosis method capable of accurately diagnosing a cell voltage measurement line may be provided.

[0008] According to some embodiments, a battery management system for managing a battery cell may be provided. The battery management system may include a battery monitoring circuit connected to the battery cell via a cell voltage measurement line, measuring a voltage of the battery cell as a first voltage via the cell voltage measurement line in a state where cell balancing of the battery cell is disabled, and measuring a voltage of the battery cell as a second voltage via the cell voltage measurement line in a state where cell balancing of the battery cell is enabled, and a processor diagnosing the cell voltage measurement line based on a difference between the first voltage and the second voltage and the first voltage.

[0009] A battery device according to some embodiments may include a battery cell, a first cell voltage measuring line connected to a positive electrode of the battery cell, a second cell voltage measuring line connected to a negative electrode of the battery cell, a first resistor connected between the first cell voltage measuring line and a first cell balancing terminal, a switch connected between the first cell balancing terminal and a second cell balancing terminal to which the second cell voltage measuring line is connected, and a processor configured to diagnose the first cell voltage measuring line or the second cell voltage measuring line based on a difference between a first voltage measured between the first cell voltage measuring line and the second cell voltage measuring line in an off state of the switch and a second voltage measured between the first cell voltage measuring line and the second cell voltage measuring line in an on state of the switch and the first voltage.

[0010] According to some embodiments, a method for diagnosing a cell voltage measurement line connected to a battery cell in a battery management system may be provided. The method may include: measuring a voltage of the battery cell as a first voltage through the cell voltage measurement line in a state where cell balancing of the battery cell is disabled; measuring a voltage of the battery cell as a second voltage through the cell voltage measurement line in a state where cell balancing of the battery cell is enabled; and diagnosing the cell voltage measurement line based on a difference between the first voltage and the second voltage and the first voltage.

[0011] FIG. 1 is a drawing showing a battery device according to some embodiments.

[0012] FIG. 2 and FIG. 3 are drawings illustrating a cell voltage measurement line diagnosis method according to some embodiments.

[0013] FIG. 4 is a flowchart illustrating a cell voltage measurement line diagnosis method according to some embodiments.

[0014] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description are omitted for clarity of description, and similar parts are designated with similar reference numerals throughout the specification.

[0015] When a component is said to be "connected" to another component, it should be understood that while it may be directly connected to that other component, there may be other components intervening. Conversely, when a component is said to be "directly connected" to another component, it should be understood that there are no other components intervening.

[0016] In the description below, expressions written in the singular may be interpreted as singular or plural, unless explicit expressions such as “one” or “single” are used.

[0017] In the flowchart described with reference to the drawing, the order of operations may be changed, several operations may be merged, some operations may be split, and certain operations may not be performed.

[0018] FIG. 1 is a drawing showing a battery device according to some embodiments.

[0019] Referring to FIG. 1, the battery device (100) may be electrically connected to an external device. In some embodiments, when the external device is a load, the battery device (100) may operate as a power source that supplies power to the load and may be discharged. When 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 a smart mobility device.

[0020] The battery device (100) may include a battery module (110) and a battery management system (BMS) (120).

[0021] The battery module (110) may include a plurality of battery cells (not shown). In some embodiments, the plurality of battery cells may be connected in series. In some embodiments, a predetermined number of battery modules (110) may be connected in series or in parallel to supply a desired power. The plurality of battery cells of the battery module (110) may each be connected to a battery management system (120) via wiring (cell voltage measurement lines). The battery management system (120) may collect and analyze information about the battery cells to control charging and discharging, cell balancing, protection operations, etc. of the battery cells. The battery management system (120) may include a battery monitoring circuit (121) and a processor (122).

[0022] The battery monitoring circuit (121) may be connected to a plurality of battery cells included in the battery module (110) through a cell voltage measurement line to monitor the status (e.g., cell voltage) of the battery cells. In some embodiments, the battery monitoring circuit (121) may include a plurality of battery monitoring circuits (121) corresponding to the plurality of battery modules (110), respectively. In some embodiments, one battery monitoring circuit (121) may correspond to two or more battery modules (110), or two or more battery monitoring circuits (121) may correspond to one battery module (110). In some embodiments, the battery monitoring circuit (121) may include a battery monitoring IC (BMIC) provided as an integrated circuit (IC).

[0023] The battery monitoring circuit (121) may include a plurality of cell balancing circuits (not shown) corresponding to each of the plurality of battery cells. Each cell balancing circuit may perform cell balancing of the corresponding battery cell. The battery monitoring circuit (121) may measure (or detect) the cell voltage of each of the plurality of battery cells. The processor (122) may transmit a control signal to the battery monitoring circuit (121) for controlling cell balancing corresponding to the corresponding battery cell according to the cell voltage of each battery cell.

[0024] The processor (122) can diagnose the cell voltage measurement line by controlling cell balancing. When the processor (122) disables cell balancing, the battery monitoring circuit (121) can measure the cell voltage of the battery cell through the cell voltage measurement line. In addition, when the processor (122) enables cell balancing, the battery monitoring circuit (121) can measure the cell voltage of the battery cell through the cell voltage measurement line. The processor (122) can diagnose the cell voltage measurement line connected to the corresponding battery cell based on the cell voltage measured in the cell balancing disabled state and the cell voltage measured in the cell balancing enabled state. The processor (122) can diagnose that there is an abnormality in the cell voltage measurement line when the ratio of the difference between the cell voltage in the cell balancing disabled state and the cell voltage in the cell balancing enabled state (e.g., the cell voltage in the cell balancing disabled state) is higher than a threshold ratio.

[0025] In some embodiments, the processor (122) may be processing circuitry, for example, a microcontroller unit (MCU).

[0026] FIGS. 2 and 3 are drawings illustrating a cell voltage measurement line diagnostic method according to some embodiments. For convenience of explanation, one battery cell is illustrated in FIGS. 2 and 3.

[0027] Referring to Figures 2 and 3, the battery cell (CV N ) can be connected to the positive and negative electrodes, respectively, for voltage measurement. The cell voltage measurement line (211) is connected to the positive and negative electrodes of the battery cell (CV N ) adjacent to the battery cell (CV N+1 ) may be a cell voltage measurement line connected to the negative pole of the battery cell (CV), and the cell voltage measurement line (212) may be a cell voltage measurement line connected to the negative pole of the battery cell (CV N ) adjacent to the battery cell (CV N-1 ) may be a cell voltage measurement line connected to the positive electrode.

[0028] The battery management system includes a cell voltage measurement line (211) and a cell terminal (CT N ) connected between the resistor (221) and the cell voltage measurement line (212) and the cell terminal (CT N-1 ) may include a resistor (222) connected between the battery cells (CV N ) is connected to the positive electrode of the cell voltage measuring line (211), the other end (node) (N1) of the cell voltage measuring line (211) is connected to the first terminal of the resistor (221), and the second terminal of the resistor (221) is connected to the cell terminal (CT N ) can be connected to the battery cell (CV). Also, one end of the cell voltage measurement line (212) can be connected to the battery cell (CV N ) is connected to the cathode of the cell voltage measuring line (212), the other end (node) (N2) of the cell voltage measuring line (212) is connected to the first terminal of the resistor (222), and the second terminal of the resistor (222) is connected to the cell terminal (CT N-1 ) can be connected to.

[0029] The battery management system may include a balancing resistor (231) and a balancing switch (240). The balancing resistor (231) is connected to a cell voltage measurement line (211) and a cell balancing terminal (CB). N ) can be connected between the second terminal (N1) of the cell voltage measurement line (211) and the cell balancing terminal (CB). For example, the balancing resistor (231) is connected between the second terminal (N1) of the cell voltage measurement line (211) and the cell balancing terminal (CB N ) can be connected between the cell balancing terminals (CB). The balancing switch (240) is connected to the cell balancing terminal (CB N ) and cell balancing terminal (CB) N-1 ) can be connected between the cell balancing terminals (CB). N-1 ) can be connected to the cell voltage measurement line (212). For example, the cell balancing terminal (CB N-1 ) can be connected to the second terminal (N2) of the cell voltage measurement line (212). In some embodiments, the cell voltage measurement line (212) and the cell balancing terminal (CB N-1 ) may be connected between the battery cells (CV). In this case, the balancing resistor (232) may be connected between the battery cells (CV N-1 ) can be used for cell balancing.

[0030] In some embodiments, the cell terminal (CT N , CT N-1 ) can be connected between the capacitors (260).

[0031] In some embodiments, the cell terminal (CT N , CT N-1 ) and cell balancing terminal (CB) N , CB N-1 ) may be a pin of the BMIC (250). In this case, the BMIC (250) may include a balancing switch (240) as shown in FIGS. 2 and 3.

[0032] In some embodiments, the cell terminal (CT N , CT N-1 ) is a pin of BMIC (250) and a cell balancing terminal (CB N , CB N-1) can be provided separately from BMIC (250).

[0033] Referring again to Figure 2, the battery management system operates the battery cell (CV) with the balancing switch (240) turned off. N ) voltage (V) CVN ) can be measured. Since no current flows in the cell voltage measurement lines (211, 212) due to the off state of the balancing switch (240), the measured voltage is the battery cell (CV N ) may be similar to the actual voltage.

[0034] Referring to Figure 3, the battery management system turns on the battery cell (CV) with the balancing switch (240) turned on. N ) voltage (V) CVN ) can be measured. The battery cell (CV) is turned on due to the balancing switch (240) being turned on. N ) can flow through the path of the cell voltage measurement line (211), resistor (231), switch (240), resistor (232), and cell voltage measurement line (212). Therefore, the battery management system can control the battery cell (CV N ) voltage (V) CVN ), a voltage drop may occur due to the line resistance (213 or 214) present in the cell voltage measurement line (211 or 212). If there is an abnormality in the cell voltage measurement line (211 or 212), the resistance value of the line resistance (213 or 214) increases, thereby increasing the battery cell (CV N ) voltage (V) CVN ) can be measured low.

[0035] Therefore, in some embodiments, the battery management system measures the voltage (V) with the balancing switch (240) turned off (i.e., cell balancing disabled). CVN (balancing off)) and the measured voltage (V) in the state where the balancing switch (240) is turned on (i.e., cell balancing enabled state) CVNBased on the difference in (balancing on)), it is possible to diagnose whether there is an abnormality in the cell voltage measurement line (211 or 212).

[0036] Meanwhile, battery cells (CV N ) is low, the current flowing through the balancing resistors (231, 232) is small, so the voltage drop in the line resistors (213, 214) may be small. In this case, the measured voltage (V) with the balancing switch (240) turned off CVN (balancing off)) and the measured voltage (V) with the balancing switch (240) turned on CVN When diagnosing an abnormality of the cell voltage measurement line (211 or 212) only by the difference between the two voltages (balancing on)), the cell voltage measurement line (211 or 212) may not be diagnosed normally because the difference between the two voltages is small. Therefore, in some embodiments, the battery management system may measure the measured voltage (V) with the balancing switch (240) turned off. CVN (balancing off)) and the measured voltage (V) with the balancing switch (240) turned on CVN Difference between (balancing on)) and battery cell (CV) N ) can be used to diagnose abnormalities in the cell voltage measurement line (211 or 212). In some embodiments, the battery cell (CV N ) with the balancing switch (240) turned off, the measured voltage (V CVN (balancing off)) can be used.

[0037] In some embodiments, the battery management system is configured to control the battery cell (CV) as in Equation 1. N ) with the balancing switch (240) turned off for the voltage (V CVN (balancing off)) and the measured voltage (V) with the balancing switch (240) turned on CVN The ratio of the difference between (balancing on)) and the critical ratio (Vratio ) can be diagnosed as abnormal in the cell voltage measurement line (211 or 212). In some embodiments, the threshold ratio (V ratio ) can be set experimentally, for example, it can be set to 0.02. That is, the battery cell (CV N ) with the balancing switch (240) turned off for the voltage (V CVN (balancing off)) and the measured voltage (V) with the balancing switch (240) turned on CVN If the ratio of the difference in (balancing on) exceeds 0.02, it can be diagnosed that there is an abnormality in the cell voltage measurement line (211 or 212) (for example, an abnormality in the line resistance (213 or 214) of the cell voltage measurement line (211 or 212)).

[0038]

[0039] In this way, the battery cell (CV N ) voltage (V) CVN The difference in relative measured voltage (|V) for (balancing off) CVN (balancing off)- V CVN (balancing on)|) diagnoses the cell voltage measurement line, so the battery cell (CV N ) can accurately diagnose abnormalities in the cell voltage measurement line even if the voltage is low.

[0040] In some embodiments, the battery management system can diagnose anomalies in the cell voltage measurement lines for each of a plurality of battery cells.

[0041] In some embodiments, a battery monitoring circuit (e.g., 121 of FIG. 1) of a battery management system monitors a battery cell (CV N ) can measure (i.e., detect) the voltage of the battery, and the processor of the battery management system (e.g., 122 of FIG. 1) can diagnose the cell voltage measurement line based on the measured voltage.

[0042] FIG. 4 is a flowchart illustrating a cell voltage measurement line diagnosis method according to some embodiments.

[0043] Referring to FIG. 4, the battery management system can measure the voltage (first voltage) of a battery cell through a cell voltage measurement line with cell balancing disabled (S410). The battery management system can measure the voltage (second voltage) of a battery cell through a cell voltage measurement line with cell balancing enabled (S420).

[0044] The battery management system can calculate a ratio of the difference between the voltage of the battery cell measured with cell balancing disabled (the first voltage) and the voltage of the battery cell measured with cell balancing enabled (the second voltage) with respect to the voltage of the battery cell measured with cell balancing disabled (the first voltage) (S430). The battery management system compares the calculated ratio with a threshold ratio (S440), and if the calculated ratio is greater than the threshold ratio, the battery management system can diagnose that there is an abnormality in the cell voltage measurement line (S450). In some embodiments, if the cell voltage measurement line is diagnosed to have an abnormality, the battery management system can generate an error flag indicating the abnormality in the cell voltage measurement line (S460). In some embodiments, the battery management system can provide the error flag to an external device. Accordingly, the external device (or a user of the external device) can take action with respect to the cell voltage measurement line. In some embodiments, if the cell voltage measurement line is diagnosed to have an abnormality, the battery management system can shut down the battery management system to prevent a fire in the battery device. If the calculated ratio is not greater than the critical ratio, the battery management system can diagnose that there is no abnormality in the cell voltage measurement line (S470).

[0045] Although the 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 made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. As a battery management system that manages battery cells, A battery monitoring circuit that is connected to the battery cell through a cell voltage measurement line, measures the voltage of the battery cell as a first voltage through the cell voltage measurement line in a state where cell balancing of the battery cell is disabled, and measures the voltage of the battery cell as a second voltage through the cell voltage measurement line in a state where cell balancing of the battery cell is enabled, and A processor that diagnoses the cell voltage measurement line based on the difference between the first voltage and the second voltage and the first voltage. A battery management system including:

2. In paragraph 1, A battery management system, wherein the processor diagnoses that there is an abnormality in the cell voltage measurement line when the ratio of the difference between the first voltage and the second voltage exceeds a threshold ratio.

3. In paragraph 2, A battery management system, wherein the processor provides an error flag indicating an abnormality in the cell voltage measurement line to an external device to which the battery device including the battery management system is connected.

4. In paragraph 1, The cell voltage measurement line includes a first cell voltage measurement line connected between the positive electrode of the battery cell and the first node, and a second cell voltage measurement line connected between the negative electrode of the battery cell and the second node, The battery management system further includes a first resistor connected between the first node and the first cell balancing terminal, The above battery monitoring circuit includes a switch connected between the first cell balancing terminal and the second cell balancing terminal, and the cell balancing is disabled by turning off the switch, and the cell balancing is enabled by turning on the switch. Battery management system.

5. In paragraph 4, A battery management system further comprising a second resistor connected between the second node and the second cell balancing terminal.

6. Battery cells, A first cell voltage measuring line connected to the positive electrode of the above battery cell, A second cell voltage measuring line connected to the negative pole of the above battery cell, A first resistor connected between the first cell voltage measurement line and the first cell balancing terminal; A switch connected between the first cell balancing terminal and the second cell balancing terminal to which the second cell voltage measurement line is connected, and A processor that diagnoses the first cell voltage measuring line or the second cell voltage measuring line based on the difference between the first voltage measured between the first cell voltage measuring line and the second cell voltage measuring line in the off state of the switch and the second voltage measured between the first cell voltage measuring line and the second cell voltage measuring line in the on state of the switch and the first voltage A battery device comprising:

7. In paragraph 6, A battery device, wherein the processor diagnoses that there is an abnormality in the first cell voltage measurement line or the second cell voltage measurement line when the ratio of the difference between the first voltage and the second voltage exceeds a threshold ratio.

8. In paragraph 7, A battery device, wherein the processor provides an error flag indicating an abnormality in the cell voltage measurement line to an external device to which the battery device is connected.

9. In paragraph 7, A battery device further comprising a second resistor connected between the second cell voltage measurement line and the second cell balancing terminal.

10. A method for diagnosing a cell voltage measurement line connected to a battery cell in a battery management system, A step of measuring the voltage of the battery cell as a first voltage through the cell voltage measurement line while disabling cell balancing of the battery cell; A step of measuring the voltage of the battery cell as a second voltage through the cell voltage measurement line while enabling cell balancing of the battery cell, and A step of diagnosing the cell voltage measurement line based on the difference between the first voltage and the second voltage and the first voltage. How to include.

11. In paragraph 10, A method wherein the diagnosing step includes a step of diagnosing that there is an abnormality in the cell voltage measurement line when the ratio of the difference between the first voltage and the second voltage exceeds a threshold ratio.

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