Method for measuring and diagnosing battery cell voltage

Abstract

The present invention presents a method for measuring and diagnosing a battery cell voltage, the method comprising the steps of: calculating a voltage across both ends of a path resistor connected to an output path of a 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 result of comparison of 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 the value of the voltage across both ends of the path resistor.

Description

Battery cell voltage measurement diagnostic method

[0001] The present invention relates to a battery cell voltage measurement circuit, and more particularly, to a battery cell voltage measurement diagnosis method for diagnosing a measurement error in a battery cell voltage measurement circuit.

[0002] Rechargeable secondary cells, or batteries, are widely used as energy sources for mobile devices such as smartphones. Furthermore, batteries are also being used as energy sources for eco-friendly vehicles, such as electric and hybrid electric vehicles, which are being proposed as a solution to air pollution caused by fossil fuel-powered gasoline and diesel vehicles. The types of applications utilizing batteries are becoming increasingly diverse, and batteries are expected to be applied to a wider range of fields and products in the future.

[0003] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages: virtually no memory effect compared to nickel-based batteries, allowing for easy charging and discharging, a very low self-discharge rate, and high energy density. Furthermore, lithium-ion batteries can be manufactured in small, lightweight designs, making them ideal power sources for mobile devices. Their expanding applications, including powering electric vehicles, are attracting attention as a next-generation energy storage medium.

[0004] These batteries are typically used in the form of battery packs rather than as single battery cells. A battery pack includes at least one battery module, which may be comprised of multiple battery cells. Battery packs are being developed with high-capacity and high-voltage specifications to meet consumer demands for longer life and more powerful operation. For example, as requirements for electric vehicles, such as driving range and maximum output, increase, the number of battery modules and cells that make up a battery pack is increasing. Meanwhile, a battery management system (BMS) is installed to manage the overall condition of the battery cells, battery modules, or battery pack.

[0005] However, in the case of a battery with multiple connected cells, repeated charging and discharging can lead to an imbalance in the charge levels of each cell. If the battery continues to discharge while in this imbalanced state, certain cells with lower charge levels will be over-discharged, compromising stable battery operation. Conversely, if the battery continues to charge while in this imbalanced state, certain cells with higher charge levels will be overcharged, jeopardizing battery safety. For example, if one battery cell has the lowest charge voltage and another has the highest charge voltage, the battery may not only charge but also fail to discharge, even if all other cells have adequate charge voltages. This imbalance in charge levels can cause some battery cells to become overcharged or over-discharged, resulting in an inability to supply power reliably to the load. Furthermore, overcharging or over-discharging of specific battery cells can not only reduce the capacity of the battery pack, but also deteriorate it and shorten its lifespan. Therefore, accurately measuring battery cell voltage is crucial. This is essential for assessing the condition of each battery cell within a confined space and controlling it accordingly. Abnormally measured battery cell voltages not only impede normal diagnostic functions, but can also compromise battery performance indicators such as SOC (State of Charge) and SOH (State of Health).

[0006] Meanwhile, if the measurement circuit is abnormal, the battery cell voltage may be measured abnormally. Therefore, it is necessary to diagnose whether the battery cell voltage is measured accurately using the measurement circuit. Conventionally, to diagnose battery cell voltage measurement, the voltages of the lines connected to the battery cell were compared. That is, the voltages measured from two lines connected in parallel to the battery cell were compared, and if the voltage difference measured from each line exceeded a certain size, a problem was determined in the battery cell voltage measurement circuit. However, the conventional method has a problem in that it cannot diagnose anomalies in the battery cell voltage measurement circuit if both lines are abnormal.

[0007] Prior art related to this includes the following:

[0008] Korean Patent No. 10-1610908

[0009] Korean Patent Publication No. 10-2023-0108604

[0010] The present invention provides a battery cell voltage measurement diagnostic method capable of diagnosing a battery cell voltage measurement circuit.

[0011] The present invention provides a battery cell voltage measurement diagnosis method that compares the voltage of a battery cell to be diagnosed with the voltage of an adjacent next battery cell, and diagnoses a battery cell voltage measurement circuit based on the comparison result and the voltage value across the path resistance of the battery cell to be diagnosed.

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

[0013] The above path resistance voltage is calculated from the difference between the voltage measured when the balancing path of the battery cell to be diagnosed is set and the voltage measured when the balancing path is not set.

[0014] If the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent next battery cell and the voltage across the path resistor is a positive value, the diagnosis is normal. If the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell and the voltage across the path resistor is a negative value, the diagnosis is normal.

[0015] Except for the case where the diagnosis is normal based on the comparison result between the voltage of the above-mentioned battery cell to be diagnosed and the voltage of the adjacent next battery cell and the value of the voltage across the path resistance, the remaining cases are diagnosed as measurement errors.

[0016] According to other embodiments of the present invention, a battery cell voltage measurement diagnosis method is a battery cell voltage measurement diagnosis method of a battery pack including a plurality of battery cells and a BMS, comprising: a process of calculating a voltage across a path resistor connected to an output path of a battery cell to be diagnosed from a voltage across an output terminal of the output path; a process of comparing the voltage of the battery cell to be diagnosed with a voltage of an adjacent next battery cell, and diagnosing it as a normal measurement if the comparison result and the voltage across the path resistor are included in a set value; and a process of diagnosing it as a voltage measurement error if the diagnosis is not normal.

[0017] The above path resistance voltage is calculated from the difference between the voltage when balancing is performed on the battery cell to be diagnosed and the voltage when balancing is not performed.

[0018] The above diagnostic target battery cell voltage (V) BC1 ), the adjacent next battery cell voltage (V BC2 ) and the voltage across the path resistance (V11) is V BC1 >V BC2 If V11>0 is satisfied, or V BC1 <VBC2 If the condition of V11<0 is satisfied, it is diagnosed as normal, and if not, it is diagnosed as a measurement error.

[0019] A battery cell voltage measurement diagnosis method according to embodiments of the present invention compares the voltage of a battery cell to be diagnosed with the voltage of an adjacent next battery cell, and diagnoses a measurement error based on the comparison result and the voltage across the path resistance 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 adjacent next battery cell, if the voltage across the path resistance is a positive value, it is diagnosed as a normal measurement, and if it is a negative value, it is diagnosed as a measurement error. In addition, when the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell, if the voltage across the path resistance is a negative value, it is diagnosed as a normal measurement, and if it is a positive value, it is diagnosed as a measurement error. At this time, the voltage across the path resistance can be calculated as the difference between the voltage across the path resistance when balancing the battery cell to be diagnosed and the voltage across the path resistance when balancing is not performed.

[0020] As described above, the present invention compares the voltage of a battery cell to be diagnosed with the voltage of an adjacent battery cell, and diagnoses a measurement error based on the value of the voltage across the path resistance, thereby diagnosing an error even when both or one of the two lines connected to one terminal of the battery cell is abnormal. In other words, the present invention can solve the problem of the conventional method of not being able to diagnose an abnormality in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are abnormal.

[0021] FIG. 1 is a circuit diagram for battery cell voltage measurement and diagnosis according to one embodiment of the present invention.

[0022] FIG. 2 is a flowchart of a battery cell voltage measurement diagnostic method according to an embodiment of the present invention.

[0023] FIG. 3 and FIG. 4 are circuit diagrams for explaining the operation according to the battery cell voltage measurement diagnosis method of the present invention.

[0024] FIG. 5 is a block diagram of a battery cell voltage measurement diagnostic device according to an embodiment of the present invention.

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided solely to ensure complete disclosure of the present invention and to fully inform those of ordinary skill in the art of the scope of the invention.

[0026] FIG. 1 is a circuit diagram for a battery cell voltage measurement diagnostic method according to one embodiment of the present invention.

[0027] Referring to FIG. 1, a circuit for battery cell voltage measurement diagnosis according to an embodiment of the present invention comprises a plurality of battery cells (BC1, BC2, BC3, …), a plurality of first lines (L11, L12, L13, L14) and second lines (L21, L22, L23, L24) connected to the positive terminals (+) and negative terminals (-) of each of the plurality of battery cells (BC1, BC2, BC3), a plurality of first resistors (R11, R12, R13, R14) and a plurality of filters (F11, F12, F13, F14) respectively provided in the plurality of first lines (L11, L12, L13, L14), a plurality of second resistors (R21, R22) selectively provided in the plurality of second lines (L21, L22, L23, L24), and a plurality of adjacent second lines (L21, L22, It may include a plurality of switches (SW11, SW12, SW13, SW14) that connect the plurality of first lines (L11, L12, L13, L14) to each other. In addition, a plurality of first measurement pins (CT1, CT2, CT3, CT4) may be provided at the ends of the plurality of first lines (L11, L12, L13, L14), and a plurality of second pins (CB1, CB2, CB3, CB4) may be provided at the ends of the plurality of second lines (L21, L22, L23, L24).

[0028] The positive terminal (+) and the negative terminal (-) of each of the plurality of battery cells (BC1, BC2, BC3) are connected to the first line (L11, L12, L13, L14) and the second line (L21, L22, L23, L24). At this time, the first line (L11, L12, L13, L14) and the second line (L21, L22, L23, L24) are respectively connected in parallel. That is, the positive terminal (+) of the first battery cell (BC1) is connected to the 1-1 line (L11) and the 2-1 line (L21) which are connected in parallel to each other, and the negative terminal (-) is connected to the 1-2 line (L12) and the 2-2 line (L22) which are connected in parallel to each other. In addition, the second battery cell (BC2) has its positive terminal (+) connected to the 1-2 line (L12) and the 2-2 line (L22) which are connected in parallel with each other, and its negative terminal (-) connected to the 1-3 line (L13) and the 2-3 line (L23) which are connected in parallel with each other. In addition, the third battery cell (BC3) has its positive terminal (+) connected to the 1-3 line (L13) and the 2-3 line (L23) which are connected in parallel with each other, and its negative terminal (-) connected to the 1-4 line (L14) and the 2-4 line (L24) which are connected in parallel with each other. That is, the first and second lines connected to the negative terminal (-) of one battery cell are connected to the positive terminal (+) of another adjacent battery cell. In other words, the negative terminals and positive terminals of two adjacent battery cells share the first and second lines with each other.

[0029] First resistors (R11, R12, R13, R14) and filters (F11, F12, F13, F14) are connected in series to the first lines (L11, L12, L13, L14), and second resistors (R21, R22) are selectively connected to the second lines (L21, L22, L23, L24). The 2-1 resistor (R21) is connected to the 2-1 line (L21), and the 2-2 resistor (R22) is connected to the 2-3 line (L23). The second resistors (R21, R22) are alternately connected to a plurality of second lines (L21, L22, L23, L24). In other words, the second resistors (R21, R22) are connected to odd-numbered second lines (L21, L23) among the plurality of second lines (L21, L22, L23, L24) and are not connected to even-numbered second lines (L22, L24). Of course, the second resistors (R21, R22) may be connected to even-numbered second lines (L22, L24) among the plurality of second lines (L21, L22, L23, L24) and are not connected to odd-numbered second lines (L21, L23). Meanwhile, the second lines (L21, L22, L23, L24) may be branched from the first lines (L11, L12, L13, L14), respectively. For example, the second line (L21, L22, L23, L24) may be branched from the node (N11, N12, N13, N14) between the first resistor (R11, R12, R13, R14) and the filter (F11, F12, F13, F14). In addition, the first line (L11, L12, L13, L14) may be provided with the first measurement pin (CT1, CT2, CT3, CT4), and the second line (L21, L22, L23, L24) may be provided with the second measurement pin (CB1, CB2, CB3, CB4).That is, the 1-1 line (L11) and the 2-1 line (L21) connected in parallel with each other are provided with the 1-1 measuring pin (CT1) and the 2-1 measuring pin (CB1), respectively, the 1-2 line (L12) and the 2-2 line (L22) connected in parallel with each other are provided with the 1-2 measuring pin (CT2) and the 2-2 measuring pin (CB2), respectively, and the 1-3 line (L13) and the 2-3 line (L23) connected in parallel with each other are provided with the 1-3 measuring pin (CT3) and the 2-3 measuring pin (CB3), respectively.

[0030] In addition, the second lines (L21, L22, L23, L24) can be connected by switches (SW11, SW12, SW13, SW14). That is, a first switch (SW11) can be provided between the 2-1 line (L21) and the 2-2 line (L22), a second switch (SW12) can be provided between the 2-2 line (L22) and the 2-3 line (L23), and a third switch (SW13) can be provided between the 2-3 line (L23) and the 2-4 line (L24). The switches (SW11, SW12, SW13) can be turned on or off according to a control signal of a predetermined level to connect or disconnect the second lines (L21, L22, L23, L24) with each other. That is, when the first switch (SW11) is turned on, the 2-1 line (L21) and the 2-2 line (L22) are connected, when the second switch (SW12) is turned on, the 2-2 line (L22) and the 2-3 line (L23) are connected, and when the third switch (SW13) is turned on, the 2-3 line (L23) and the 2-4 line (L24) can be connected.

[0031] Fig. 2 is a flowchart illustrating a battery cell voltage measurement diagnosis method according to an embodiment of the present invention. In addition, Figs. 3 and 4 are circuit diagrams illustrating the operation of the battery cell voltage measurement diagnosis method according to an embodiment of the present invention. That is, Fig. 3 is a circuit diagram illustrating the current direction according to the voltage magnitude of the next battery cell adjacent to the battery cell to be diagnosed, and Fig. 4 is a circuit diagram illustrating a process for calculating the voltage across the path resistance according to the present invention.

[0032] Referring to FIG. 2, a battery cell voltage measurement diagnosis method according to an embodiment of the present invention includes a path resistance cross-terminal voltage calculation process (S110) for calculating the voltage across the path resistance connected to the output path of the battery cell to be diagnosed from the voltage at the output terminal of the output path, and a battery cell voltage (V) to be diagnosed BC1 ) and the next battery cell voltage (V BC2 ) and the process of comparing the voltage of the battery cell to be diagnosed (S120) as a result of the comparison (V BC1 ) is the voltage of the next adjacent battery cell (V BC2 ) is greater than (V BC1 >V BC2 )(S130) Check whether the measured value of the voltage at both ends of the path resistance is a positive value (S140) If it is a positive value, it is judged as a normal diagnosis (S150) If it is a negative value, it is judged as a diagnosis error (S160), and as a result of the comparison, the voltage of the battery cell to be diagnosed (V BC1 ) is the voltage of the next adjacent battery cell (V BC2 ) is less than (V BC1 <V BC2 ) It may include a process of checking whether the measured value of the voltage at both ends of the path resistance is a negative value (S170), determining that it is a normal diagnosis if it is a negative value (S180), and determining that it is a diagnosis error if it is a positive value (S190).

[0033] Before explaining a diagnostic method according to an embodiment of the present invention, the current direction according to the voltage of two adjacent battery cells will be explained using FIG. 3. FIG. 3 is a circuit diagram for explaining the current direction according to the voltage magnitude of a battery cell adjacent to a battery cell to be diagnosed. When a plurality of battery cells (BC1, BC2, BC3, BC4) are connected, and among the switches (SW11, SW12, SW13, SW14) connected to the second lines (L21, L22, L23, L24), for example, the first and second switches (SW11, SW12) connected to the adjacent first and second battery cells (BC1, BC2) are turned on, 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). At this time, the direction of the current is determined according to the voltage magnitude of the battery cells (BC1, BC2). For example, when the voltage of the first battery cell (BC1) is greater than that of the second battery cell (BC2), the current flows from the positive terminal of the first battery cell (BC1) to the negative terminal of the first battery cell (BC1) through the first-first resistor (R11), the second-first resistor (R21), and the first-second resistor (R12). However, when the voltage of the first battery cell (BC1) is greater than that of the second battery cell (BC2), the current flows in the opposite direction. Therefore, the present invention uses this principle to diagnose voltage measurement depending on whether the magnitude of the voltage across the path resistance is a positive value or a negative value.

[0034] The battery cell voltage measurement diagnostic method according to one embodiment of the present invention is described in detail for each process as follows.

[0035] S110: Balancing of the battery cell to be diagnosed is performed to calculate the voltage across the first path resistance. 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, SW14) are turned off to balance the first battery cell (BC1). In this case, a current (I11) flows along a path as illustrated in FIG. 4. That is, when the first switch (SW11) is turned on to balance the first battery cell (BC1), a current (I11) flows from the positive terminal of the first battery cell (BC1) through the 1-1 resistor (R11), the 2-1 resistor (R21), and the 1-2 resistor (R12) to the negative terminal of the first battery cell (BC1). Of course, the flow of this current (I11) assumes that the voltage of the first battery cell (BC1) is greater than the voltage of the second battery cell (BC2). At this time, a voltage drop occurs due to the 1-2 resistor (R12) 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 balancing can be calculated as in [Mathematical Formula 1] through the voltage difference before and after the current flows. Here, Vx is the voltage value of the first node (N11) where the 2-2 line (L22) branches from the 1-2 line (L12), and this voltage value of the first node (N11) can be measured at the 1-2 measurement pin (CT2).

[0036]

[0037] That is, the path resistance voltage (V11) can be calculated by subtracting the voltage applied to the node when balancing is not performed from the voltage applied to the node when balancing is performed on the battery cell (BC1) to be diagnosed.

[0038] S120: Compare the voltage of the battery cell to be diagnosed with the voltage of the adjacent battery cell. For example, if the first battery cell (BC1) is the battery cell to be diagnosed, the voltage (V) of the first battery cell (BC1) BC1 ) and the voltage (V) of the second battery cell (BC2) adjacent to the first battery cell (BC1) BC2 ) are compared.

[0039] S130 and S140: If the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent battery cell as a result of comparing the voltage of the battery cell to be diagnosed (S130), the value of the voltage across the first path resistor (V11) is checked (S140). In other words, it is checked whether the value of the voltage across the first path resistor (V11) is a positive value.

[0040] S150 and S160: If the value of the voltage across the first path resistor (V11) is positive, it is diagnosed as normal measurement (S150), and if it is negative, it is diagnosed as a measurement error (S160).

[0041] S130 and S170: If the voltage of the battery cell to be diagnosed is lower than the voltage of the adjacent battery cell (S130), the value of the voltage across the path resistor (V11) is checked (S170). In other words, check whether the value of the voltage across the path resistor (V11) is negative.

[0042] S180 and S190: If the value of the path resistance voltage (V11) is negative, it is diagnosed as normal measurement (S180), and if it is positive, it is diagnosed as a measurement error (S190).

[0043] That is, the present invention is to determine V according to the magnitude of the voltage of the battery cell to be diagnosed and the voltage of the next battery cell adjacent to it. BC1 >V BC2 If V11>0, or V BC1 <V BC2If the condition of V11<0 is satisfied, it is judged as a normal diagnosis, and if both conditions are not satisfied, it is judged as a diagnosis error. That is, if the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent next battery cell, it is diagnosed as a normal measurement when the voltage across the path resistance is a positive value, and if the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell, it is diagnosed as a normal measurement when the resistance across the path resistance is a negative value.

[0044] FIG. 5 is a block diagram illustrating the configuration of a device for battery cell voltage measurement and diagnosis according to an embodiment of the present invention. That is, the circuit for battery cell voltage measurement and diagnosis of FIG. 1 can be connected to a diagnostic device to configure a diagnostic device such as that of FIG. 5.

[0045] Referring to FIG. 5, a battery cell voltage measurement diagnostic device according to an embodiment of the present invention may include a battery module (100) including a plurality of battery cells (BC1, BC2, BC3), and a diagnostic unit (200) that diagnoses a voltage measurement error of a battery cell to be diagnosed. Here, the diagnostic unit (200) may be provided within a BMS. In addition, the diagnostic unit (200) may include a measuring unit (210) that is connected to a plurality of first measuring pins (CT1, CT2, CT3, CT4) and a plurality of second measuring pins (CB1, CB2, CB3, CB4) of the diagnostic circuit to measure voltage, a comparing unit (220) that compares the voltage of a battery cell to be diagnosed with the voltage of an adjacent next battery cell and compares the measured value of the voltage across the path resistance accordingly, and a judgment control unit (230) that generates a control signal that controls switches (SW1, SW12, SW13, SW14) and judges the measurement diagnosis result according to the comparison result of the comparing unit (220).

[0046] The measuring unit (210) is connected to a plurality of first measuring pins (CT1, CT2, CT3, CT4) and a plurality of second measuring pins (CB1, CB2, CB3, CB4). The measuring unit (210) measures voltages through the plurality of first measuring pins (CT1, CT2, CT3, CT4) and the plurality of second measuring pins (CB1, CB2, CB3, CB4). That is, the measuring unit (210) can measure the voltage of a battery cell to be diagnosed through the first measuring pins (CT1, CT2, CT3, CT4) and the second measuring pins (CB1, CB2, CB3, CB4) connected thereto. In addition, the measuring unit (210) according to the present invention can measure the voltage when performing cell balancing on a specific battery cell and the voltage when performing cell balancing on the corresponding battery cell. That is, the measuring unit (210) measures the voltage when balancing the battery cell to be diagnosed is performed and the voltage when balancing is not performed, and calculates the voltage across the path resistance (V11) accordingly.

[0047] The comparison unit (220) compares the voltage of the battery cell to be diagnosed with the voltage of the adjacent next battery cell. In addition, the comparison unit (220) compares the value of the voltage across the path resistance according to 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 resistance of the battery cell to be diagnosed. At this time, the voltage across the path resistance can be calculated by subtracting the voltage when battery cell balancing is performed and the voltage when it is not performed.

[0048] The judgment control unit (230) judges the measurement diagnosis result according to the value of the path resistance both terminal voltage according to the comparison result of the comparison unit (220). That is, the judgment control unit (230) diagnoses a normal measurement if the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent next battery cell and the path resistance both terminal voltage has a positive value according to the comparison result of the comparison unit (220), and diagnoses a measurement error if it has a negative value. In addition, the judgment control unit (230) diagnoses a normal measurement if the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell and the path resistance both terminal voltage has a negative value according to the comparison result of the comparison unit (220), and diagnoses a measurement error if it has a positive value. At this time, if it is diagnosed as a measurement error, it can be determined that at least one of the plurality of first measurement pins (CT1, CT2, CT3, CT4) and the plurality of second measurement pins (CB1, CB2, CB3, CB4) is abnormal or that a problem has occurred in the circuit. Meanwhile, the judgment control unit (230) can control the switches (SW11, SW12, SW13, SW14) by generating a control signal that controls the switches (SW11, SW12, SW13, SW14). That is, the judgment control unit (230) can control the switch connected to the measurement pin of the battery cell to select the battery cell to be diagnosed and perform balancing of the battery cell. In addition, the judgment control unit (230) can control the switches connected to two battery cells to make the voltage of the battery cell to be diagnosed and the voltage of the next battery cell adjacent to it.

[0049] As described above, a battery cell voltage measurement diagnosis method according to an embodiment of the present invention compares the voltage of a battery cell to be diagnosed with the voltage of an adjacent next battery cell, and if the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent next battery cell and the voltage across the path resistor is a positive value, it is determined to be normal, and if the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell and the voltage across the path resistor is a negative value, it is determined to be normal. At this time, 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 and measuring the voltage across the path resistor when balancing is not performed and subtracting them.

[0050] The conventional method has a problem in that it cannot diagnose a problem in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are abnormal. However, the present invention compares the voltage of the battery cell to be diagnosed with the voltage of the adjacent next battery cell, and determines the error based on the value of the voltage across the path resistance, thereby diagnosing an error even when both or one of the two lines connected to one terminal of the battery cell is abnormal. In other words, the present invention can solve the problem of the conventional method in that it cannot diagnose a problem in the battery cell voltage measurement circuit when both lines connected to one terminal of the battery cell are abnormal.

[0051] While the technical concepts of the present invention have been specifically described through the above-described embodiments, it should be noted that the embodiments are intended for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, those skilled in the art will appreciate that various embodiments are possible within the scope of the technical concepts of the present invention.

[0052] The names of each symbol used in the description and drawings of the invention are as follows.

[0053] BC1, BC2, BC3: Battery cells L11, L12, L13, L14: Line 1

[0054] L21, L22, L23, L24: Second line R11, R12, R13, R14; First resistor

[0055] R21, R22: Second resistor SW11, SW12, SW13, SW14: Switch

[0056] 100: Battery module 200: BMS

[0057] 210: Measurement section 220: Comparison section

[0058] 230: Judgment Control Unit

[0059]

Claims

1. As a diagnostic method for measuring battery cell voltage, A process of calculating the voltage across the path resistance connected to the output path of the battery cell to be diagnosed; A process of comparing the voltage of the above-mentioned battery cell to the voltage of the adjacent next battery cell; and A battery cell voltage measurement diagnosis method including a process of diagnosing a measurement error based on the above comparison result and the value of the voltage across the path resistance.

2. A battery cell voltage measurement diagnosis method according to claim 1, wherein the path resistance voltage is calculated from the difference between the voltage measured when the balancing path of the battery cell to be diagnosed is set and the voltage measured when the balancing path is not set.

3. A battery cell voltage measurement diagnosis method according to claim 2, wherein if the voltage of the battery cell to be diagnosed is greater than the voltage of the adjacent next battery cell and the voltage across the path resistance is a positive value, the diagnosis is normal, and if the voltage of the battery cell to be diagnosed is less than the voltage of the adjacent next battery cell and the voltage across the path resistance is a negative value, the diagnosis is normal.

4. A battery cell voltage measurement and diagnosis method according to claim 3, in which the remaining cases are diagnosed as measurement errors, except for cases in which normal diagnosis is made based on the comparison result between the voltage of the battery cell to be diagnosed and the voltage of the adjacent next battery cell and the value of the voltage across the path resistance.

5. A method for measuring battery cell voltage of a battery pack including a plurality of battery cells and a BMS, A process of calculating the voltage at both ends of a path resistor connected to the output path of a battery cell to be diagnosed from the voltage at the output terminal of the output path; A process of comparing the voltage of the above-mentioned battery cell to the voltage of the adjacent next battery cell, and diagnosing it as a normal measurement if the comparison result and the voltage across the path resistance are included in the set value; and A battery cell voltage measurement diagnosis method including a process of diagnosing a voltage measurement error when the above normal diagnosis is not made.

6. A battery cell voltage measurement diagnosis method according to claim 5, wherein the voltage across the path resistance is calculated from the difference between the voltage when balancing is performed on the battery cell to be diagnosed and the voltage when balancing is not performed.

7. In claim 6, the voltage of the battery cell to be diagnosed (V) BC1 ), the adjacent next battery cell voltage (V BC2 ) and the voltage across the path resistance (V11) is V BC1 >V BC2 If V11>0 is satisfied, or V BC1 <V BC2 A battery cell voltage measurement diagnosis method that diagnoses a normal condition when the condition of V11<0 is satisfied, and diagnoses a measurement error in any other case.

Images