Battery cell voltage measurement and diagnostic method

Abstract

The present invention discloses a battery cell voltage measurement and diagnosis method, comprising: a first process for calculating the voltage across a path resistor connected to the output path of a battery cell to be diagnosed; a second process for calculating the voltage across a path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed; a process for comparing the voltage across the first path resistor and the voltage across the second path resistor; and a process for diagnosing a measurement error based on the comparison result of the voltages across the first and second path resistors.

Description

TECHNICAL FIELD

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

BACKGROUND ART

[0002] Rechargeable secondary batteries, that is, batteries, are widely used as energy sources for mobile devices such as smartphones. Furthermore, batteries are also used as energy sources for environmentally friendly vehicles such as electric vehicles and hybrid electric vehicles, which are proposed as solutions to address air pollution caused by gasoline vehicles and diesel vehicles that use fossil fuels. The types of applications that use batteries have become extremely diversified, and it is expected that batteries will be applied to even more fields and products than at present in the future.

[0003] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium-ion batteries and the like. Among them, lithium-ion batteries are in the spotlight for their advantages of almost no memory effect compared to nickel-based batteries, allowing free charging and discharging, extremely low self-discharge rate, and high energy density. In addition, lithium-ion batteries can be made compact and lightweight, so they are used as power sources for mobile devices, their scope of use has expanded to power sources for electric vehicles, and they are attracting attention as next-generation energy storage media.

[0004] Such batteries are typically used in the form of battery packs rather than as single battery cells. A battery pack comprises at least one battery module, and a battery module may consist of multiple battery cells. Battery packs are being developed with higher capacity and higher voltage specifications to meet consumer demands for longer lifespan and more powerful operation. For example, the number of battery modules and battery cells constituting a battery pack is increasing as requirements for electric vehicles, such as driving range and maximum output, are rising. Meanwhile, a Battery Management System (BMS) is provided to manage the overall status of battery cells, battery modules, or battery packs.

[0005] However, in the case of a battery with multiple connected battery cells, repeated charging and discharging can lead to an imbalance in the charge levels of each battery cell. If the battery continues to discharge in this state of charge imbalance, certain battery cells with low charge levels may become over-discharged, making it difficult for the battery to operate stably. Conversely, if the battery continues to charge in this state of charge imbalance, certain battery cells with high charge levels may become overcharged, compromising the safety of the battery. For example, if one battery cell has the lowest charge voltage and the other battery cells have the highest charge voltage, even if all other battery cells have appropriate charge voltages, the battery will have a problem where it cannot discharge as well as charge. Thus, an imbalance in charge levels can cause some battery cells to become overcharged or over-discharged, and this problem can lead to an inability to stably supply power to the load. Furthermore, overcharging or over-discharging of specific battery cells can not only reduce the capacity of the battery pack but also lead to battery pack degradation, which can result in a shortened lifespan. Therefore, accurately measuring the voltage of battery cells is crucial. In other words, judging the state of each battery cell within a limited space and accurately measuring the voltage of the battery cells based on that judgment is an essential requirement for controlling the battery cells. If the voltage of a battery cell is measured as an abnormal value, there is a concern that normal diagnostic functions may not be able to be performed, or that problems may arise with performance indicators such as SOX (State of Charge (SOC), State of Health (SOH) and other battery performance indicators).

[0006] On the other hand, if a malfunction occurs in the measurement circuit, the battery cell voltage may be measured as an abnormal value. Therefore, it becomes necessary to diagnose whether or not the battery cell voltage has been measured accurately using the measurement circuit. Existing methods have been used to diagnose battery cell voltage measurement by comparing the voltages of lines connected to the battery cell. That is, the voltages measured in two lines connected in parallel to the battery cell were compared, and if the voltage difference measured in each line was greater than a predetermined magnitude, it was determined that there was a problem with the battery cell voltage measurement circuit. However, the conventional method has the problem that it cannot diagnose a malfunction in the battery cell voltage measurement circuit if both lines are malfunctioning.

[0007] Related prior art includes the following: [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Korean Registered Patent Publication No. 10-1610908 [Patent Document 2] Korean Published Patent No. 10-2023-0108604 [Overview of the project] [Problems that the invention aims to solve]

[0009] This invention provides a battery cell voltage measurement and diagnosis method that can diagnose a battery cell voltage measurement circuit.

[0010] This invention provides a battery cell voltage measurement and diagnosis method that diagnoses a battery cell voltage measurement circuit by comparing measured values ​​with calculated values ​​of battery cell voltage. [Means for solving the problem]

[0011] A battery cell voltage measurement and diagnosis method according to one embodiment of the present invention includes: a first process for calculating the voltage across a path resistor connected to the output path of a battery cell to be diagnosed; a second process for calculating the voltage across a path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed; a process for comparing the voltage across the first path resistor and the voltage across the second path resistor; and a process for diagnosing a measurement error based on the comparison result of the voltages across the first and second path resistors.

[0012] The voltage across the first path resistor is calculated from the difference between the voltage measured with the balancing path of the battery cell to be diagnosed set and the voltage measured without the balancing path set.

[0013] The voltage across the second path resistor is calculated from the voltage of the battery cell being diagnosed, the sum of the resistance values ​​of the output path of the battery cell being diagnosed, and the resistance value of the path resistor.

[0014] The voltage across the second path resistor is calculated by dividing the voltage of the battery cell being diagnosed by the sum of the resistance values ​​of the output path and multiplying it by the resistance value of the path resistor.

[0015] If the voltage across the first and second path resistors differs by more than a predetermined reference value, a voltage measurement error is diagnosed.

[0016] Another embodiment of the present invention provides a method for measuring and diagnosing the voltage of a battery cell in a battery pack comprising a plurality of battery cells and a battery management system (BMS), comprising: a first process for calculating the voltage across a path resistor, which calculates the voltage across the path resistor connected to the output path of the battery cell to be diagnosed from the voltage at the output terminal of the output path; a second process for calculating the voltage across the path resistor, which calculates the voltage across the path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed; and a process for diagnosing a voltage measurement error when the difference between the voltages across the first and second path resistors exceeds a predetermined reference value.

[0017] The voltage (V11) across the first path resistance is calculated according to [Equation 1] from the voltage (Vx(balancing ON)) when balancing the battery cell to be diagnosed and the voltage (Vx(balancing OFF)) when balancing is not performed.

[0018]

Equation

[0019] The voltage (V12) across the second path resistance is calculated according to [Equation 2] from the voltage (V BC1 ) of the battery cell to be diagnosed, the sum of the resistance values of the output paths (Rm), and the resistance value of the path resistance (R12).

[0020]

Equation

Effects of the Invention

[0021] In the battery cell voltage measurement and diagnosis method according to one embodiment of the present invention, the voltage across the first path resistance and the voltage across the second path resistance of the battery cell to be diagnosed are compared, and a diagnosis error can be determined when the comparison result is larger than a reference value. That is, an error can be diagnosed by comparing the measured value of the battery cell voltage (the voltage across the first path resistance) with the calculated value (the voltage across the second path resistance). At this time, the voltage across the first path resistance can be calculated by measuring the voltage applied across the path resistance when balancing the battery cell to be diagnosed, measuring the voltage applied across the path resistance when balancing is not performed, and performing a subtraction between these values. Note that the voltage across the second path resistance can be calculated using the voltage of the battery cell to be diagnosed and the resistance values of the plurality of resistors provided in the output path.

[0022] As described above, the present invention compares the voltages across the first and second path resistors and determines the error based on the comparison result, thereby enabling the diagnosis of an error even when both lines connected to a single terminal of a battery cell are abnormal, or when only one of them is abnormal. In other words, the present invention solves the problem of conventional methods that could not diagnose an abnormality in the battery cell voltage measurement circuit when both lines connected to a single terminal of a battery cell were abnormal. [Brief explanation of the drawing]

[0023] [Figure 1] This is a circuit diagram for measuring and diagnosing battery cell voltage according to one embodiment of the present invention. [Figure 2] This is a flowchart of a battery cell voltage measurement and diagnosis method according to one embodiment of the present invention. [Figure 3] This is a circuit diagram illustrating the operation of the battery cell voltage measurement and diagnostic method of the present invention. [Figure 4] This is a block diagram of a battery cell voltage measurement and diagnostic device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention is not limited in any way to the embodiments disclosed below and can be embodied in a variety of different forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform those in the ordinary skill of the scope of the invention.

[0025] Figure 1 is a circuit diagram for a battery cell voltage measurement and diagnosis method according to one embodiment of the present invention.

[0026] Referring to Figure 1, the circuit for measuring and diagnosing battery cell voltage according to one embodiment of the present invention comprises a plurality of battery cells BC1, BC2, BC3, ... and a plurality of first lines L11, L12, L13, L14 and second lines L21, L22, L23, L24 connected to the positive terminal + and negative terminal - of each of the plurality of battery cells BC1, BC2, BC3, and a plurality of first lines L11, L12, L13, The device may also include a plurality of first resistors R11, R12, R13, R14 and a plurality of filters F11, F12, F13, F14, each provided on L14, a plurality of second resistors R21, R22 selectively provided on a plurality of second lines L21, L22, L23, L24, and a plurality of switches SW11, SW12, SW13, SW14 connecting adjacent second lines L21, L22, L23, L24 to each other. Alternatively, a plurality of first measuring 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.

[0027] The positive terminal (+) and negative terminal (-) of each of the multiple battery cells BC1, BC2, and BC3 are connected to the first lines L11, L12, L13, L14 and the second lines L21, L22, L23, L24. At this time, the first lines L11, L12, L13, L14 and the second lines L21, L22, L23, L24 are connected in parallel. That is, the positive terminal (+) of the first battery cell BC1 is connected to the 1st-1 line L11 and the 2nd-1 line L21, which are connected in parallel with each other, and the negative terminal (-) is connected to the 1st-2 line L12 and the 2nd-2 line L22, which are connected in parallel with each other. Furthermore, the second battery cell BC2 has its positive terminal + connected to the 1st-2nd line L12 and the 2nd-2nd line L22, which are connected in parallel to each other, and its negative terminal - connected to the 1st-3rd line L13 and the 2nd-3rd line L23, which are connected in parallel to each other. The third battery cell BC3 has its positive terminal + connected to the 1st-3rd line L13 and the 2nd-3rd line L23, which are connected in parallel to each other, and its negative terminal - connected to the 1st-4th line L14 and the 2nd-4th line L24, which are connected in parallel to each other. In other words, the 1st and 2nd lines connected to the negative terminal - of one battery cell are connected to the positive terminal + of the other adjacent battery cell. In other words, two adjacent battery cells share the 1st and 2nd lines for their negative and positive terminals.

[0028] The first lines L11, L12, L13, and L14 are connected in series with the first resistors R11, R12, R13, and R14 and filters F11, F12, F13, and F14, respectively. The second lines L21, L22, L23, and L24 are selectively connected with the second resistors R21 and R22. The second resistor R21 is connected to the second line L21, and the second resistor R22 is connected to the second line L23. The second resistors R21 and R22 are alternately connected to multiple second lines L21, L22, L23, and L24. In other words, the second resistors R21 and R22 are connected to the odd-numbered second lines L21 and L23 among the multiple second lines L21, L22, L23, and L24, and not to the even-numbered second lines L22 and L24. Needless to say, the second resistors R21 and R22 are connected to the even-numbered second lines L22 and L24 among the multiple second lines L21, L22, L23, and L24, and do not need to be connected to the odd-numbered second lines L21 and L23. On the other hand, the second lines L21, L22, L23, and L24 may be branched from the first lines L11, L12, L13, and L14, respectively. For example, the second lines L21, L22, L23, L24 may branch off from nodes N11, N12, N13, N14 between the first resistors R11, R12, R13, R14 and the filters F11, F12, F13, F14. Furthermore, the first lines L11, L12, L13, L14 may be provided with first measurement pins CT1, CT2, CT3, CT4, while the second lines L21, L22, L23, L24 may be provided with second measurement pins CB1, CB2, CB3, CB4. Specifically, the first-first line L11 and the second-first line L21, which are connected in parallel to each other, are provided with the first-first measurement pin CT1 and the second-first measurement pin CB1, respectively; the first-second line L12 and the second-second line L22, which are connected in parallel to each other, are provided with the first-second measurement pin CT2 and the second-second measurement pin CB2, respectively; and the first-third line L13 and the second-third line L23, which are connected in parallel to each other, are provided with the first-third measurement pin CT3 and the second-third measurement pin CB3, respectively.

[0029] Furthermore, the second lines L21, L22, L23, and L24 may be connected by switches SW11, SW12, SW13, and SW14. Specifically, a first switch SW11 may be provided between the second-first line L21 and the second-second line L22, a second switch SW12 may be provided between the second-second line L22 and the second-third line L23, and a third switch SW13 may be provided between the second-third line L23 and the second-fourth line L24. Switches SW11, SW12, and SW13 can be turned on or turned off based on a predetermined level of control signal to connect or disconnect the second lines L21, L22, L23, and L24 from one another. In other words, 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 are connected.

[0030] Figure 2 is a flowchart illustrating a battery cell voltage measurement and diagnosis method according to one embodiment of the present invention. Figure 3 is a circuit diagram illustrating the calculation process of the voltage across the first path resistance according to the battery cell voltage measurement and diagnosis method according to one embodiment of the present invention.

[0031] Referring to Figure 2, a battery cell voltage measurement and diagnosis method according to one embodiment of the present invention may include: a first process of calculating the voltage across a path resistor (S110) which calculates the voltage across the path resistor connected to the output path of the battery cell to be diagnosed from the voltage at the output terminal of the output path; a second process of calculating the voltage across a path resistor (S120) which calculates the voltage across the path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed; a process of comparing the voltage across the first path resistor and the voltage across the second path resistor (S130); a process of diagnosing a voltage measurement error if the difference between the voltages across the first and second path resistors exceeds a predetermined reference value (S150); and a process of diagnosing normality if the difference between the voltages across the first path resistor and the voltages across the second path resistor is below a reference value (S140). A description of each process in this battery cell voltage measurement and diagnosis method according to one embodiment of the present invention is as follows.

[0032] S110: To calculate the voltage across the first path resistance, the battery cell to be diagnosed is balanced. 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 I along the path shown in Figure 3 is N This will result in a current flowing. In other words, when the first switch SW11 is turned on for balancing the first battery cell BC1, a current I will flow 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. NCurrent flows through the circuit. At this time, a voltage drop occurs across the first-second resistor R12, and the voltage (V11) is measured. Therefore, using the difference in voltage before and after the current flows, the voltage (V11) before and after balancing can be calculated according to the following equation 1. Here, Vx is the voltage value at node N12 where the second-second line L22 branches off from the first-second line L12, and the voltage value at such node N12 can be measured at the first-second measurement pin CT2.

[0033]

number

[0034] In other words, the voltage across the first path resistance (V11) can be calculated by subtracting the voltage across the node when balancing is not performed from the voltage across the node when balancing is performed on the battery cell being diagnosed.

[0035] S120: The voltage across the second path resistor can be calculated because the voltages of the first and second resistors applied to the diagnostic circuit and the battery cell are known. That is, the voltage across the second path resistor (V12) is the current I flowing through the output path of the battery cell being diagnosed. N And since the resistance value of resistor R12 in the output path is known, the current I N And it can be calculated from the resistance value of resistor R12 according to formula 2.

[0036]

number

[0037] Also, current I N This refers to the voltage (V) of the battery cell being diagnosed, i.e., the first battery cell BC1. BC1The voltage and the resistance of the output path, i.e., the sum of the resistance values ​​of the 1st-1st resistor R11, the 2nd-1st resistor R21, and the 1st-2nd resistor R12, can be calculated according to the following formula 3. In the following formula 3, Rm is the sum of the resistance values ​​of the output path.

[0038]

number

[0039] Therefore, the voltage across the second path resistor (V12) can be calculated from equations 2 and 3 as shown in equation 4. That is, the voltage across the second path resistor (V12) is equal to the voltage of the first battery cell BC1 (V BC1 The voltage can be calculated by dividing the voltage by the sum of the resistance values ​​in the output path (Rm) and multiplying it by the resistance value of resistor R12, which causes the voltage drop.

[0040]

number

[0041] S130, S140, and S150: The voltage across the first path resistor (V11) and the voltage across the second path resistor (V12) are compared (S130). That is, the measured value and the calculated value of the voltage across the path resistors are compared. If the difference between the voltage across the first path resistor (V11) and the voltage across the second path resistor (V12) is greater than a predetermined reference value, an error is diagnosed (S150). If the difference between the voltage across the first path resistor (V11) and the voltage across the second path resistor (V12) is smaller than a reference value, it is diagnosed as normal (S140).

[0042] Figure 4 is a block diagram illustrating the configuration of a device for measuring and diagnosing battery cell voltage according to one embodiment of the present invention. That is, the circuit for measuring and diagnosing battery cell voltage shown in Figure 1 can be connected to a diagnostic device to configure a diagnostic device as shown in Figure 4.

[0043] Referring to Figure 4, a battery cell voltage measurement and diagnostic device according to one embodiment of the present invention may include a battery module 100 having a plurality of battery cells BC1, BC2, BC3, and a diagnostic unit 200 that diagnoses voltage measurement errors of the battery cells to be diagnosed. Here, the diagnostic unit 200 may be provided within the BMS. The diagnostic unit 200 may also include a measurement unit 210 that measures voltage by being connected to a plurality of first measurement pins CT1, CT2, CT3, CT4 and a plurality of second measurement pins CB1, CB2, CB3, CB4 of the diagnostic circuit, a storage unit 220 that stores information such as the voltage of the battery cells BC1, BC2, BC3 constituting the diagnostic circuit, the resistance values ​​of a plurality of resistors, and current, a comparison unit 230 that compares the voltage across the first path resistor and the voltage across the second path resistor, and a judgment control unit 240 that generates control signals to control switches SW11, SW12, SW13, SW14 and determines the measurement and diagnostic result based on the comparison result in the comparison unit 230.

[0044] The measurement unit 210 is connected to a plurality of first measurement pins CT1, CT2, CT3, CT4 and a plurality of second measurement pins CB1, CB2, CB3, CB4. Such a measurement unit 210 measures voltage via the plurality of first measurement pins CT1, CT2, CT3, CT4 and the plurality of second measurement pins CB1, CB2, CB3, CB4. In other words, the measurement unit 210 can measure the voltage of the battery cell to be diagnosed via the first measurement pins CT1, CT2, CT3, CT4 and the second measurement pins CB1, CB2, CB3, CB4 connected to it. Furthermore, the measurement unit 210 according to the present invention can measure the voltage when cell balancing is performed on a specific battery cell and the voltage when cell balancing is not performed on the battery cell. That is, the measurement unit 210 measures the voltage when balancing is performed on the battery cell to be diagnosed and the voltage when balancing is not performed on the battery cell, and based on the measurement results, it can calculate the voltage across the first path resistance (V11).

[0045] The memory unit 220 can store the characteristics or specifications of the battery cells BC1, BC2, BC3 and each component that constitute the diagnostic circuit. Specifically, the memory unit 220 stores data such as the charge or discharge voltage of battery cells BC1, BC2, BC3, the current voltage state of battery cells BC1, BC2, BC3, the resistance values ​​of the multiple first resistors R11, R12, R13, R14 that constitute the diagnostic circuit, the resistance values ​​of the multiple second resistors R21, R22, and the current values ​​of battery cells BC1, BC2, BC3 based on the resistance values ​​of the first and second resistors and the voltage values ​​of battery cells BC1, BC2, BC3. In addition, the memory unit 220 can store measured values ​​such as the voltage when cell balancing is performed on a specific battery cell measured by the measurement unit 210, and the voltage when cell balancing is not performed on the same battery cell.

[0046] The comparison unit 230 compares the voltage across the first path resistor and the voltage across the second path resistor of the battery cell to be diagnosed. That is, the comparison unit 230 compares the measured value and the calculated value of the voltage across the path resistors. To do this, first, the comparison unit 230 uses the voltage when cell balancing is performed on the battery cell to be diagnosed from the measurement unit 210 and the voltage when cell balancing is not performed on the battery cell, and calculates the difference. That is, the comparison unit 230 calculates the voltage across the first path resistor of the battery cell to be diagnosed. Next, the comparison unit 230 calculates the voltage across the second path resistor using the voltage of the battery cell to be diagnosed from the memory unit 220 and the resistance values ​​of the multiple resistors provided in the output path. That is, the comparison unit 230 calculates the voltage across the second path resistor according to equations 2 to 4. Then, the comparison unit 230 compares the voltages across the first and second path resistors.

[0047] The decision control unit 240 determines the measurement diagnosis result based on the comparison result in the comparison unit 230. Specifically, if the comparison value between the voltage across the first path resistor and the voltage across the second path resistor, which were compared in the comparison unit 230, is greater than a set reference value, the decision control unit 240 diagnoses a measurement error. If the comparison value between the voltage across the first path resistor and the voltage across the second path resistor is less than a reference value, the decision control unit 240 diagnoses a normal measurement. In this case, if a measurement error is diagnosed, the decision control unit 240 can determine that at least one of the multiple first measurement pins CT1, CT2, CT3, CT4 and the multiple second measurement pins CB1, CB2, CB3, CB4 is abnormal, or that an abnormality has occurred in the circuit. On the other hand, the decision control unit 240 can control switches SW11, SW12, SW13, and SW14 by generating control signals to control them. In other words, the decision control unit 240 can select a battery cell to be diagnosed and control a switch connected to the measurement pin of that battery cell to perform balancing of that battery cell.

[0048] As described above, the battery cell voltage measurement and diagnosis method according to one embodiment of the present invention compares the voltage across the first path resistor with the voltage across the second path resistor, and if the result of the comparison is greater than the reference value, a diagnostic error can be determined. In this case, the voltage across the first path resistor can be calculated by subtracting the voltage across the path resistor when the battery cell is not balanced from the voltage across the path resistor when the battery cell is balanced. The voltage across the second path resistor can be calculated using the voltage of the battery cell to be diagnosed and the resistance values ​​of multiple resistors provided in the output path.

[0049] Conventional methods have the problem that they cannot diagnose an abnormality in the battery cell voltage measurement circuit when both lines connected to a single terminal of a battery cell are abnormal. However, the present invention compares the voltages across the first and second path resistors and determines the error based on the comparison result, thereby enabling the diagnosis of an error even when both lines connected to a single terminal of a battery cell are abnormal, or when only one of them is abnormal.

[0050] As described above, the technical concept of the present invention has been specifically described based on the embodiments described above, but it should be noted that these embodiments are for illustrative purposes only and not for limitation. Furthermore, those skilled in the art in the field of the present invention should understand that various embodiments are possible within the scope of the technical concept of the present invention.

[0051] The names of the reference numerals used in the description of the invention and in the drawings are as follows: [Explanation of Symbols]

[0052] BC1, BC2, BC3: Battery cells L11, L12, L13, L14: First line L21, L22, L23, L24: Second line R11, R12, R13, R14: First resistor R21, R22: Second resistor SW11, SW12, SW13, SW14: Switches 100: Battery Module 200: Diagnostic Department 210: Measuring part 220: Storage section 230: Comparison section 240: Decision Control Unit

Claims

1. A method for measuring and diagnosing battery cell voltage, The first process for calculating the voltage across the path resistor connected to the output path of the battery cell to be diagnosed, A second process for calculating the voltage across the path resistor, which calculates the voltage across the path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed, A process of comparing the voltage across the first path resistor and the voltage across the second path resistor, A process for diagnosing measurement errors based on the comparison results of the voltages across the first path resistance and the second path resistance, A method for measuring and diagnosing battery cell voltage, including the above.

2. The battery cell voltage measurement and diagnosis method according to claim 1, wherein the voltage across the first path resistor is calculated from the difference between the voltage measured with the balancing path of the battery cell to be diagnosed set and the voltage measured with the balancing path not set.

3. The battery cell voltage measurement and diagnosis method according to claim 2, wherein the voltage across the second path resistor is calculated from the voltage of the battery cell to be diagnosed, the sum of the resistance values ​​of the output path of the battery cell to be diagnosed and the resistance value of the path resistor.

4. The battery cell voltage measurement and diagnosis method according to claim 3, wherein the voltage across the second path resistor is calculated by dividing the voltage of the battery cell to be diagnosed by the sum of the resistance values ​​of the output path and multiplying by the resistance value of the path resistor.

5. The battery cell voltage measurement and diagnosis method according to claim 4, wherein a voltage measurement error is diagnosed when the voltage across the first path resistance and the second path resistance differs by more than a predetermined reference value.

6. A method for measuring and diagnosing the battery cell voltage of a battery pack comprising multiple battery cells and a battery management system (BMS), A first process for calculating the voltage across a path resistor, which calculates the voltage across the path resistor connected to the output path of the battery cell to be diagnosed from the voltage at the output terminal of the output path, A second process for calculating the voltage across the path resistor, which calculates the voltage across the path resistor from the resistance value of the output path and the voltage of the battery cell to be diagnosed, A process for diagnosing a voltage measurement error when the voltage across the first path resistance and the second path resistance differs by more than a predetermined reference value, A method for measuring and diagnosing battery cell voltage, including the measurement method.

7. The battery cell voltage measurement and diagnosis method according to claim 6, wherein the voltage across the first path resistor (V11) is calculated from the voltage when balancing the battery cell to be diagnosed (Vx (balancing ON)) and the voltage when balancing is not performed (Vx (balancing OFF)) according to [Formula 1]. [Math 1] …１

8. The voltage across the second path resistor (V12) is equal to the voltage of the battery cell being diagnosed (V ＢＣ１ A method for measuring and diagnosing battery cell voltage according to claim 7, wherein the voltage is calculated according to [Formula 2] from the sum of the resistance values ​​of the output path (Rm) and the resistance value of the path resistance (R12). [Math 2] …２

Images