Method for diagnosing and measuring voltage of battery cell

Abstract

The present invention provides a method for measuring and diagnosing a voltage of a battery cell, the method comprising the steps of: calculating a voltage across a path resistor connected to an output path of the battery cell to be diagnosed; comparing the voltage of the battery cell to be diagnosed with the voltage of the next battery cell adjacent to the battery cell to be diagnosed; and diagnosing a measurement error according to the comparison result of the voltage of the battery cell to be diagnosed and the voltage of the next battery cell adjacent to the battery cell to be diagnosed and the value of the voltage across the path resistor.

Description

Methods for diagnosing and measuring battery cell voltage Technical Field

[0001] This invention relates to a battery cell voltage measurement circuit, and more particularly to a battery cell voltage measurement diagnostic method for diagnosing measurement errors in the battery cell voltage measurement circuit. Background Technology

[0002] Rechargeable batteries, or rechargeable batteries, are widely used as energy sources for mobile devices such as smartphones. Furthermore, batteries are used as an energy source for environmentally friendly vehicles such as electric vehicles and hybrid electric vehicles, proposed as a solution to air pollution caused by fossil fuel-powered gasoline and diesel vehicles. The types of applications using batteries are becoming increasingly diverse, and it is expected that batteries will be used in even more fields and products in the future than they are now.

[0003] Currently available batteries include nickel-cadmium (NiCd), nickel-metal hydride (NiMH), nickel-zinc (NiZn), and lithium-ion (Li-ion) batteries. Among these, lithium-ion batteries have attracted significant attention due to their advantages of free charge / discharge, very low self-discharge rate, and high energy density, as they exhibit virtually no memory effect compared to nickel-based batteries. Furthermore, because lithium-ion batteries can be manufactured in a smaller size and are lightweight, they are used as power sources for mobile devices, and their applications have expanded to include electric vehicles, thus gaining attention as a next-generation energy storage medium.

[0004] These batteries are typically used in the form of battery packs rather than as individual battery cells. A battery pack includes at least one or more battery modules, and a battery module can consist of multiple battery cells. Battery packs have been developed with high capacity and high voltage specifications, enabling them to be used and driven for longer periods in response to consumer demand. For example, as requirements for electric vehicles, such as driving range and maximum output, are increasing, the number of battery modules and battery cells constituting a battery pack is also increasing. Simultaneously, a battery management system (BMS) is implemented to manage the overall state of the battery cells, battery modules, or battery pack.

[0005] However, in the case of a battery with multiple battery cells, the charge level of each cell becomes uneven during repeated charging and discharging. When the battery continues to discharge in an uneven state, the cell with the lowest charge level becomes over-discharged, making stable battery operation difficult. Conversely, when the battery continues to charge in an uneven state, the cell with the highest charge level becomes overcharged, compromising battery safety. For example, if any one cell is at its lowest charging voltage and all other cells are at their highest charging voltage, the battery may fail to charge and discharge properly, even if all other cells have appropriate charging voltages. Therefore, uneven charge levels can lead to some cells being overcharged or over-discharged, resulting in unstable power supply to the load. Furthermore, overcharging or over-discharging of specific cells can cause not only a reduction in battery pack capacity but also battery pack degradation and a shortened battery life. Therefore, accurate measurement of battery cell voltage is crucial. In other words, accurate measurement of battery cell voltage is essential for determining the state of each battery cell within a confined space and for controlling the battery cells based on that determined state. When abnormal battery cell voltage is measured, not only may normal diagnostic functions fail, but problems may also arise when performing SOX (including battery performance indicators such as state of charge (SOC) and state of health (SOH)) estimations.

[0006] Simultaneously, when the measurement circuit malfunctions, the battery cell voltage can be measured abnormally. Therefore, it is necessary to diagnose whether the measurement circuit has accurately measured the battery cell voltage. Conventionally, the voltages of the lines connected to the battery cell are compared to each other to diagnose the battery cell voltage measurement. That is, the voltages measured on the two lines connected in parallel with the battery cell are compared to each other, and when the difference between the voltages measured on the lines is greater than a certain level, it is determined that there is a problem with the battery cell voltage measurement circuit. However, the problem with the conventional method is that when both lines are malfunctioning, the conventional method cannot diagnose the malfunction in the battery cell voltage measurement circuit.

[0007] Examples of related technologies include Korean registered patent No. 10-1610908 and Korean unexamined patent publication No. 10-2023-0108604. Summary of the Invention

[0008] Technical issues

[0009] This invention provides a method for diagnosing battery cell voltage measurement, wherein a battery cell voltage measurement circuit can be used for diagnosis.

[0010] This invention provides a method for diagnosing battery cell voltage measurement. The method compares the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and diagnoses the battery cell voltage measurement circuit based on the comparison result and the voltage value across the path resistor of the battery cell to be diagnosed.

[0011] Technical solution

[0012] A method for diagnosing battery cell voltage measurement according to an embodiment of the present invention includes: a process of calculating the voltage across a path resistor connected to the output path of the battery cell to be diagnosed; a process of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell; and a process of diagnosing a measurement error based on the comparison result and the value of the voltage across the path resistor.

[0013] The voltage across the path resistor is calculated based on the difference between the voltage measured when the equalization path of the battery cell to be diagnosed is set and the voltage measured when the equalization path of the battery cell to be diagnosed is not set.

[0014] The measurement is considered normal when the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell and the voltage across the path resistor is positive; and the measurement is considered normal when the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell and the voltage across the path resistor is negative.

[0015] All other cases, except those where the measurement is diagnosed as normal based on the comparison between the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell, and the value of the voltage across the path resistor, will be diagnosed as measurement errors.

[0016] According to another embodiment of the present invention, a method for diagnosing the measurement of battery cell voltage is a method for diagnosing the measurement of battery cell voltage in a battery pack comprising multiple battery cells and a battery management system, and the method includes: a process of calculating the voltage across a path resistor connected to the output path based on the voltage at the output terminal of the output path of the battery cell to be diagnosed; a process of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and diagnosing the measurement as normal when the comparison result and the voltage across the path resistor are included in a set value; and a process of diagnosing an error in the voltage measurement when the measurement is not diagnosed as normal.

[0017] The voltage across the path resistor is calculated based on the difference between the voltage measured when balancing the battery cell to be diagnosed is performed and the voltage measured when balancing the battery cell to be diagnosed is not performed.

[0018] When the voltage V of the battery cell to be diagnosed BC1 The voltage V of the next adjacent battery cell BC2 and the voltage V across the path resistor 11 Satisfy V BC1 >V BC2 And V 11 The condition is greater than 0, or V is satisfied. BC1 <V BC2 And V 11 If the value is less than 0, the measurement is diagnosed as normal; otherwise, it is diagnosed as an error in the measurement.

[0019] Beneficial effects

[0020] In the method for diagnosing battery cell voltage measurement according to an embodiment of the present invention, the voltage of the battery cell to be diagnosed is compared with the voltage of the next adjacent battery cell, and a measurement error is diagnosed based on the comparison result and the voltage across the path resistor of the battery cell to be diagnosed. That is, when the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell, if the voltage across the path resistor is positive, the measurement is diagnosed as normal; if it is negative, it is diagnosed as a measurement error. When the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell, if the voltage across the path resistor is negative, the measurement is diagnosed as normal; if it is positive, it is diagnosed as a measurement error. In this case, the voltage across the path resistor can be calculated as the difference between the voltage across the path resistor when balancing the battery cell to be diagnosed is performed and the voltage across the path resistor when balancing the battery cell to be diagnosed is not performed.

[0021] As described above, in this invention, measurement errors are diagnosed by comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell and based on the value of the voltage across the path resistor. This allows for the diagnosis of measurement errors even when both lines connected to one terminal of the battery cell are faulty, or when one of the two lines is faulty. In other words, according to this invention, the problem that conventional methods cannot diagnose abnormalities in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are faulty can be solved. Attached Figure Description

[0022] Figure 1 is a circuit diagram of a circuit for diagnosing the measurement of battery cell voltage according to an embodiment of the present invention.

[0023] Figure 2 is a flowchart of a method for diagnosing battery cell voltage measurement according to an embodiment of the present invention.

[0024] Figures 3 and 4 are circuit diagrams illustrating the operation of a method for measuring the voltage of a battery cell according to the present invention.

[0025] Figure 5 is a block diagram of an apparatus for diagnosing the measurement of battery cell voltage according to an embodiment of the present invention. Detailed Implementation

[0026] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but will be implemented in various different forms, and these embodiments are provided only to make the disclosure complete and to fully inform those skilled in the art of the scope of the invention.

[0027] Figure 1 is a circuit diagram of a method for measuring the voltage of a battery cell according to an embodiment of the present invention.

[0028] Referring to FIG1, the circuit for diagnosing battery cell voltage measurement according to an embodiment of the present invention may include multiple battery cells BC1, BC2, BC3..., multiple first lines L11, L12, L13 and L14 respectively connected to the positive (+) and negative (-) terminals of the multiple battery cells BC1, BC2, BC3, and L14, multiple second lines L21, L22, L23 and L24, multiple first resistors R11, R12, R13 and R14 respectively disposed on the multiple first lines L11, L12, L13 and L14, multiple filters F11, F12, F13 and F14, multiple second resistors R21 and R22 selectively disposed on the multiple second lines L21, L22, L23 and L24, and multiple switches SW11, SW12, SW13 and SW14 connecting adjacent second lines L21, L22, L23 and L24 to each other. In addition, multiple first measurement pins CT1, CT2, CT3 and CT4 can be respectively set at the corresponding ends of multiple first lines L11, L12, L13 and L14, and multiple second pins CB1, CB2, CB3 and CB4 can be respectively set at the corresponding ends of multiple second lines L21, L22, L23 and L24.

[0029] The positive (+) and negative (-) terminals of multiple battery cells BC1, BC2, and BC3 are connected to the first lines L11, L12, L13, and L14 and the second lines L21, L22, L23, and L24. In this case, the first lines L11, L12, L13, and L14 are connected in parallel with the second lines L21, L22, L23, and L24. That is, the positive (+) terminal of the first battery cell BC1 is connected to the parallel-connected lines 1-1 L11 and 2-1 L21, and the negative (-) terminal of the first battery cell BC1 is connected to the parallel-connected lines 1-2 L12 and 2-2 L22. Furthermore, the positive (+) terminal of the second battery cell BC2 is connected to the parallel-connected lines 1-2 L12 and 2-2 L22. The negative terminal (-) of the second battery cell BC2 is connected to lines 1-3 (L13) and 2-3 (L23) which are connected in parallel. Furthermore, the positive terminal (+) of the third battery cell BC3 is connected to lines 1-3 (L13) and 2-3 (L23) which are connected in parallel, and the negative terminal (-) of the third battery cell BC3 is connected to lines 1-4 (L14) and 2-4 (L24) which are connected in parallel. In other words, the first and second lines connected to the negative terminal (-) of one battery cell are connected to the positive terminal (+) of the adjacent battery cell. In other words, the negative and positive terminals of two adjacent battery cells share the first and second lines.

[0030] First resistors R11, R12, R13, and R14, and filters F11, F12, F13, and F14, are connected in series to the first lines L11, L12, L13, and L14, respectively. Second resistors R21 and R22 are selectively connected to the second lines L21, L22, L23, and L24. A second-first resistor R21 is connected to the second-first line L21, and a second-second resistor R22 is connected to the second-third line L23. Second resistors R21 and R22 are alternately connected to multiple second lines L21, L22, L23, and L24. In other words, second resistors R21 and R22 are connected to the odd-numbered second lines L21 and L23, but not to the even-numbered second lines L22 and L24. Of course, the second resistors R21 and R22 can be connected to the even-numbered second lines L22 and L24 among the multiple second lines L21, L22, L23, and L24, and can be excluded from connection to the odd-numbered second lines L21 and L23. Simultaneously, the second lines L21, L22, L23, and L24 can branch from the first lines L11, L12, L13, and L14, respectively. For example, the second lines L21, L22, L23, and L24 can branch from nodes N11, N12, N13, and N14 between the first resistors R11, R12, R13, and R14 and the filters F11, F12, F13, and F14, respectively. Furthermore, the first measurement pins CT1, CT2, CT3, and CT4 can be respectively set on the first lines L11, L12, L13, and L14, and the second measurement pins CB1, CB2, CB3, and CB4 can be respectively set on the second lines L21, L22, L23, and L24. That is, the first-1 measurement pin CT1 and the second-1 measurement pin CB1 are respectively set on the first-1 line L11 and the second-1 line L21, which are connected in parallel; the first-2 measurement pin CT2 and the second-2 measurement pin CB2 are respectively set on the first-2 line L12 and the second-2 line L22, which are connected in parallel; and the first-3 measurement pin CT3 and the second-3 measurement pin CB3 are respectively set on the first-3 line L13 and the second-3 line L23, which are connected in parallel.

[0031] Furthermore, the second lines L21, L22, L23, and L24 can be connected via switches SW11, SW12, SW13, and SW14. That is, the first switch SW11 can be positioned between line 2-1 L21 and line 2-2 L22, the second switch SW12 can be positioned between line 2-2 L22 and line 2-3 L23, and the third switch SW13 can be positioned between line 2-3 L23 and line 2-4 L24. Switches SW11, SW12, and SW13 can be turned on or off according to a control signal with a predetermined level to connect or disconnect the second lines L21, L22, L23, and L24 from each other. In other words, when the first switch SW11 is turned on, line 2-1 L21 and line 2-2 L22 can be connected to each other; when the second switch SW12 is turned on, line 2-2 L22 and line 2-3 L23 can be connected to each other; and when the third switch SW13 is turned on, line 2-3 L23 and line 2-4 L24 can be connected to each other.

[0032] Figure 2 is a flowchart of a method for measuring the voltage of a battery cell according to an embodiment of the present invention. Furthermore, Figures 3 and 4 are circuit diagrams illustrating the method for measuring the voltage of a battery cell according to an embodiment of the present invention. Specifically, Figure 3 is a circuit diagram illustrating the current direction based on the voltage magnitude of the battery cell to be diagnosed and the voltage magnitude of the next adjacent battery cell, and Figure 4 is a circuit diagram illustrating the process of calculating the voltage across a path resistor according to the present invention.

[0033] Referring to Figure 2, a method for measuring the voltage of a battery cell according to an embodiment of the present invention may include: a voltage calculation process across a path resistor, wherein the voltage calculation process across the path resistor is calculated based on the voltage at the output terminal of the output path of the battery cell to be diagnosed (S110); and the voltage V of the battery cell to be diagnosed is then measured. BC1 The voltage V of the next adjacent battery cell BC2 The comparison process (S120); the inspection process, as a result of the comparison, when the voltage V of the battery cell to be diagnosed... BC1 Greater than the voltage V of the next adjacent battery cell BC2 (V) BC1 >V BC2 (S130) In this inspection process, the measured value of the voltage across the path resistor is checked to see if it is positive (S140), and if the measured value is positive, it is determined to be a normal diagnosis (S150), and if the measured value is negative, it is determined that there is an error in the diagnosis (S160); and in the inspection process, as a comparison result, when the voltage V of the battery cell to be diagnosed is... BC1Less than the voltage V of the next adjacent battery cell BC2 (V) BC1 <V BC2 (S130) The inspection process checks whether the measured value of the voltage across the path resistor is negative (S170), and if the measured value is negative, it is determined to be a normal diagnosis (S180), and if the measured value is positive, it is determined that there is an error in the diagnosis (S190).

[0034] Before describing the method for measuring the voltage of a battery cell according to an embodiment of the present invention, the current direction based on the voltage of two adjacent battery cells will be described using FIG3. FIG3 is a circuit diagram for describing the current direction based on the voltage magnitude of the battery cell to be diagnosed and the next adjacent battery cell. In the switches SW11, SW12, SW13, and SW14 connected to the plurality of battery cells BC1, BC2, BC3, and BC4 and connected to the second lines L21, L22, L23, and L24, for example, when the first switch SW11 and the second switch SW12 connected to the adjacent first battery cell BC1 and the second battery cell BC2 are turned on, the current flows along each path. That is, the first current I11 flows along the path of the first battery cell BC1, and the second current I12 flows along the path of the second battery cell BC2. In this case, the current direction is determined according to the voltage magnitude of battery cells BC1 and BC2. For example, when the voltage of the first battery cell BC1 is greater than the voltage of the second battery cell BC2, current flows from the positive terminal of the first battery cell BC1 through resistors R11 (first-1), R21 (second-1), and R12 (first-2) to the negative terminal of the first battery cell BC1. However, when the voltage of the first battery cell BC1 is greater than the voltage of the second battery cell BC2, the current flows in the opposite direction. Therefore, this invention uses this principle to diagnose voltage measurements based on whether the voltage across the path resistors is positive or negative.

[0035] The following describes a method for measuring the voltage of a battery cell according to an embodiment of the present invention, for each process.

[0036] S110: Perform balancing of the battery cell to be diagnosed to calculate the first voltage across the path resistors. For example, when the first battery cell BC1 is selected as the battery cell to be diagnosed, the first switch SW11 is turned on and the remaining switches SW12, SW13, and SW14 are turned off to balance the first battery cell BC1. In this case, the current I11 flows along the path shown in Figure 4. That is, when the first switch SW11 is turned on to balance the first battery cell BC1, the current I11 flows from the positive terminal of the first battery cell BC1 through resistors R11 (1-1), R21 (2-1), and R12 (1-2) to the negative terminal of the first battery cell BC1. Of course, this flow of current I11 is assumed when the voltage of the first battery cell BC1 is greater than the voltage of the second battery cell BC2. In this case, a voltage drop occurs due to resistor R12 (1-2), and the voltage V11 is measured. That is, a voltage drop occurs between the first node N11 and the negative terminal of the first battery cell BC1. Therefore, the voltage V11 before and after equalization can be calculated as shown in Formula 1 by the voltage difference before and after current flow. Here, Vx is the voltage value of the first node N11 of the branch of line 2-2 L22 from line 1-2 L12, and the voltage value of the first node N11 can be measured at the 1-2 measurement pin CT2.

[0037] [Formula 1]

[0038] V11=V x (Equal opening) -V x (Balance)

[0039] In other words, the voltage V11 across the path resistor can be calculated by subtracting the voltage applied to the node when balancing the battery cell BC1 without performing the diagnosis from the voltage applied to the node when balancing the battery cell BC1 without performing the diagnosis.

[0040] S120: Compare the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell. For example, when the first battery cell BC1 is the battery cell to be diagnosed, compare the voltage V of the first battery cell BC1. BC1 The voltage V of the second battery cell BC2 adjacent to the first battery cell BC1. BC2 .

[0041] S130 and S140: When the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell (S130), the value of the voltage V11 across the first path resistor is checked (S140). That is, the value of the first voltage V11 across the path resistor is checked to see if it is positive.

[0042] S150 and S160: When the value of the first voltage V11 across the path resistor is positive, the measurement is diagnosed as normal (S150), and when it is negative, an error is diagnosed in the measurement (S160).

[0043] S130 and S170: As a comparison result between the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell, when the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell (S130), the value of the voltage V11 across the path resistor is checked (S170). That is, the value of the voltage V11 across the path resistor is checked to see if it is negative.

[0044] S180 and S190: When the voltage V11 across the path resistor is negative, it is diagnosed as normal (S180); if it is positive, it is diagnosed as an error in the measurement (S190).

[0045] In other words, in this invention, based on the voltage magnitude of the battery cell to be diagnosed and the voltage magnitude of the next adjacent battery cell, when V... BC1 >V BC2 And V 11 The condition > 0 or V BC1 <V BC2 And V 11 When the voltage of the battery cell to be diagnosed is less than 0, the measurement is considered normal. If neither of these conditions is met, the measurement is considered incorrect. In other words, if the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell, the measurement is considered normal when the voltage across the path resistor is positive. If the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell, the measurement is considered normal when the voltage across the path resistor is negative.

[0046] Figure 5 is a block diagram illustrating the configuration of an apparatus for diagnosing the measurement of battery cell voltage according to an embodiment of the present invention. That is, the circuit for diagnosing the measurement of battery cell voltage of Figure 1 can be connected to a diagnostic device to form the diagnostic device shown in Figure 5.

[0047] Referring to FIG5, an apparatus for diagnosing battery cell voltage measurements according to an embodiment of the present invention may include: a battery module 100 comprising a plurality of battery cells BC1, BC2, and BC3; and a diagnostic unit 200 for diagnosing errors in voltage measurement in the battery cell to be diagnosed. Here, the diagnostic unit 200 may be located within a battery management system (BMS). Furthermore, the diagnostic unit 200 may include: a measurement unit 210 connected to a plurality of first measurement pins CT1, CT2, CT3, and CT4 and a plurality of second measurement pins CB1, CB2, CB3, and CB4 of a diagnostic circuit to measure voltage; a comparison unit 220 comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and correspondingly comparing the measured values ​​of the voltage across a path resistor; and a determination control unit 230 generating control signals for controlling switches SW11, SW12, SW13, and SW14, and determining a diagnostic result for the measurement based on the comparison result of the comparison unit 220.

[0048] Measurement unit 210 is connected to a plurality of first measurement pins CT1, CT2, CT3, and CT4 and a plurality of second measurement pins CB1, CB2, CB3, and CB4. Measurement unit 210 measures voltage via the plurality of first measurement pins CT1, CT2, CT3, and CT4 and the plurality of second measurement pins CB1, CB2, CB3, and CB4. That is, measurement unit 210 can measure the voltage of the battery cell to be diagnosed via the first measurement pins CT1, CT2, CT3, and CT4 and the second measurement pins CB1, CB2, CB3, and CB4 connected to the battery cell to be diagnosed. Furthermore, according to the invention, measurement unit 210 can measure the voltage when cell balancing of a specific battery cell is performed and the voltage when cell balancing of the corresponding battery cell is not performed. That is, measurement unit 210 measures the voltage when balancing of the battery cell to be diagnosed is performed and the voltage when balancing of the battery cell to be diagnosed is not performed, and accordingly calculates the first voltage V11 across the path resistor.

[0049] The comparison unit 220 compares the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell. Furthermore, the comparison unit 220 compares the voltage across the path resistor based on the comparison result between the voltage of the battery cell to be diagnosed and the voltage of the next battery cell. In other words, the comparison unit 220 calculates the voltage across the path resistor of the battery cell to be diagnosed. In this case, the voltage across the path resistor can be calculated by subtracting the voltage when battery cell balancing is performed from the voltage when battery cell balancing is not performed.

[0050] The determination control unit 230 determines the result of the diagnostic measurement based on the comparison result of the comparison unit 220 and the value of the voltage across the path resistor. That is, based on the comparison result of the comparison unit 220, the determination control unit 230 diagnoses the measurement as normal when the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell and the voltage across the path resistor is positive, and diagnoses it as a measurement error when the voltage across the path resistor is negative. Furthermore, based on the comparison result of the comparison unit 220, the determination control unit 230 diagnoses the measurement as normal when the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell and the voltage across the path resistor is negative, and diagnoses it as a measurement error when the voltage across the path resistor is positive. In this case, when a measurement error is diagnosed, at least one of the multiple first measurement pins CT1, CT2, CT3, and CT4 and the multiple second measurement pins CB1, CB2, CB3, and CB4 may be abnormal, or a circuit malfunction may have occurred. Simultaneously, the determination control unit 230 can generate control signals for controlling switches SW11, SW12, SW13, and SW14. That is, the determination control unit 230 can select the battery cell to be diagnosed and control the switch connected to the measurement pin of the corresponding battery cell, thereby performing battery cell equalization. Furthermore, the determination control unit 230 can control the switches connected to two battery cells to allow measurement of the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell.

[0051] As described above, in the method for measuring the voltage of a battery cell according to an embodiment of the present invention, the voltage of the battery cell to be diagnosed is compared with the voltage of the next adjacent battery cell. If the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell, and the voltage across the path resistor is positive, the measurement is determined to be a normal measurement. If the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell, and the voltage across the path resistor is negative, the measurement is determined to be a normal measurement. In this case, the voltage across the path resistor can be calculated by measuring the voltage across the path resistor when balancing the battery cell to be diagnosed is performed and when balancing is not performed, and by performing a subtraction between the voltages across the path resistor.

[0052] A problem with traditional methods is that they cannot diagnose abnormalities in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are faulty. However, in this invention, by comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell and diagnosing the measurement error based on the voltage across the path resistor, measurement errors can be diagnosed even if both lines connected to one terminal of the battery cell are faulty or one of the lines is faulty. In other words, according to this invention, the problem of traditional methods being unable to diagnose abnormalities in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are faulty can be solved.

[0053] The technical concept of the present invention described above has been described in detail according to the above embodiments. However, it should be noted that the above embodiments are for description purposes only and not for limitation. Furthermore, those skilled in the art will understand that various embodiments are possible within the scope of the technical concept of the present invention.

[0054] The names of the reference numerals used in the specification and drawings of this invention are as follows: BC1, BC2, BC3: battery cells; L11, L12, L13, L1: first circuit; L21, L22, L23, L24: second circuit; R11, R12, R13, R14: first resistor; R21, R22: second resistor; SW11, SW12, SW13, SW14: switch; 100: battery module; 200: battery management system; 210: measurement unit; 220: comparison unit; 230: determination control unit.

Claims

1. A method for measuring and diagnosing the voltage of a battery cell, the method comprising: The process of calculating the voltage across the path resistor connected to the output path of the battery cell to be diagnosed. The process of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell; And the process of diagnosing measurement errors based on the comparison results and the voltage values ​​across the path resistor.

2. The method according to claim 1, wherein, The voltage across the path resistor is calculated based on the difference between the voltage measured when the equalization path of the battery cell to be diagnosed is set and the voltage measured when the equalization path of the battery cell to be diagnosed is not set.

3. The method according to claim 2, wherein, The measurement is considered normal when the voltage of the battery cell to be diagnosed is greater than the voltage of the next adjacent battery cell and the voltage across the path resistor is positive; and the measurement is considered normal when the voltage of the battery cell to be diagnosed is less than the voltage of the next adjacent battery cell and the voltage across the path resistor is negative.

4. The method according to claim 3, wherein, All other cases, except those where the measurement is diagnosed as normal based on the comparison between the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell, and the value of the voltage across the path resistor, will be diagnosed as measurement errors.

5. A method for measuring the cell voltage of a battery pack comprising multiple battery cells and a battery management system, the method comprising: The process of calculating the voltage across the path resistor connected to the output path based on the voltage at the output terminal of the output path of the battery cell to be diagnosed. The process of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and diagnosing the measurement as normal when the comparison result and the voltage across the path resistor are included in a set value; and the process of diagnosing an error in the voltage measurement when the measurement is not diagnosed as normal.

6. The method according to claim 5, wherein, The voltage across the path resistor is calculated based on the difference between the voltage measured when balancing the battery cell to be diagnosed is performed and the voltage measured when balancing the battery cell to be diagnosed is not performed.

7. The method according to claim 6, wherein, When the voltage V of the battery cell to be diagnosed BC1 The voltage V of the next adjacent battery cell BC2 and the voltage V across the path resistor 11 Satisfy V BC1 >V BC2 And V 11 The condition is greater than 0, or V is satisfied. BC1 <V BC2 And V 11 If the value is less than 0, the measurement is diagnosed as normal; otherwise, it is diagnosed as an error in the measurement.

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