Battery cell voltage measurement and diagnostic method

Abstract

The present invention discloses a method for measuring and diagnosing battery cell voltage, comprising the steps of: calculating the voltage across a path resistor connected to the 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 adjacent battery cell; and diagnosing a measurement error based on the result of the comparison and the value of the voltage across the path resistor.

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 diagnostic method for diagnosing measurement errors in a battery cell voltage measurement circuit. [Background technology]

[0002] Rechargeable secondary batteries, or batteries, are widely used as an energy source for mobile devices such as smartphones. Furthermore, batteries are also used as an energy source for environmentally friendly vehicles such as electric vehicles and hybrid electric vehicles, which are presented as solutions to address air pollution caused by fossil fuel-using gasoline and diesel vehicles. The types of applications using batteries are extremely diverse, and it is expected that batteries will be applied to even more 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 attracting attention for their advantages over nickel-based batteries, such as their minimal memory effect, allowing for flexible charging and discharging, extremely low self-discharge rates, and high energy density. Furthermore, because lithium-ion batteries can be manufactured to be small and lightweight, their use has expanded from powering mobile devices to electric vehicles, making them a promising next-generation energy storage medium.

[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 each battery cell based on that judgment is an essential requirement for controlling battery cells. If the voltage of a battery cell is measured as an abnormal value, not only will normal diagnostic functions not be possible, but there is also a concern that problems may arise with performance indicators such as SOX (State of Charge (SOC), State of Health (SOH), etc.).

[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 was measured accurately. 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] The present invention provides a battery cell voltage measurement and diagnosis method that 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 resistance of the battery cell to be diagnosed. [Means for solving the problem]

[0011] A method for measuring and diagnosing a battery cell voltage according to an embodiment of the present invention includes a step of calculating a voltage across a path resistor connected to an output path of a battery cell to be diagnosed, a step of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and a step of diagnosing a measurement error based on the result of the comparison and the value of the voltage across the path resistor.

[0012] The voltage across the path resistor is calculated from the difference between the voltage measured in a state where the balancing path of the battery cell to be diagnosed is set and the voltage measured in a state where the balancing path is not set.

[0013] If the voltage of the battery cell to be diagnosed is larger than the voltage of the next adjacent battery cell and the voltage across the path resistor is a positive value, it is diagnosed as normal, and if the voltage of the battery cell to be diagnosed is smaller than the voltage of the next adjacent battery cell and the voltage across the path resistor is a negative value, it is diagnosed as normal.

[0014] Based on the result of comparing 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, a measurement error is diagnosed in the remaining cases except the case where it is diagnosed as normal.

[0015] A method for measuring and diagnosing a battery cell voltage according to another embodiment of the present invention is a method for measuring and diagnosing a battery cell voltage of a battery pack including a plurality of battery cells and a battery management system (BMS), the method comprising: a step of calculating a voltage across a path resistor connected to an output path of a battery cell to be diagnosed from the voltage at the output end of the output path, a step of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, and diagnosing a normal measurement when the comparison result and the voltage across the path resistor fall within a set value, and a step of diagnosing a voltage measurement error when the measurement is not diagnosed as normal.

[0016] The voltage across the path resistance is calculated from the difference between the voltage when balancing the battery cell to be diagnosed and the voltage when balancing is not performed.

[0017] The voltage of the battery cell to be diagnosed (V BC1 ) and the voltage of the next adjacent battery cell (V BC2 ) and the voltage (V11) across the path resistance satisfy V BC1 >V BC2 , when the condition of V11>0 is satisfied, or the voltage of the battery cell to be diagnosed (V BC1 ) and the voltage of the next adjacent battery cell (V BC2 ) and the voltage (V11) across the path resistance satisfy V BC1 <V BC2 , when the condition of V11<0 is satisfied, it is diagnosed as normal, and in other cases, it is diagnosed as a measurement error. Effects of the Invention

[0018] In the battery cell voltage measurement and diagnosis method according to the 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 resistance of the battery cell to be diagnosed. That is, when the voltage of the battery cell to be diagnosed is even larger than the voltage of the next adjacent battery cell, if the voltage across the path resistance is a positive value, the measurement is diagnosed as normal, and if it is a negative value, the measurement is diagnosed as a measurement error. When the voltage of the battery cell to be diagnosed is even smaller than the voltage of the next adjacent battery cell, if the voltage across the path resistance is a negative value, the measurement is diagnosed as normal, and if it is a positive value, the measurement is diagnosed as a measurement error. At this time, the voltage across the path resistance can be calculated from the difference between the voltage applied across the path resistance when balancing the battery cell to be diagnosed and the voltage applied across the path resistance when balancing is not performed.

[0019] As described above, the present invention compares the voltage of the battery cell under diagnosis with the voltage of the next adjacent battery cell and diagnoses the measurement error based on the value of the voltage across the path resistance. This allows for the diagnosis of an error even if both lines connected to a single terminal of a battery cell are abnormal, or even if 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]

[0020] [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 circuit diagram illustrating the operation of the battery cell voltage measurement and diagnostic method of the present invention. [Figure 5] 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]

[0021] 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.

[0022] Figure 1 is a circuit diagram for a battery cell voltage measurement and diagnosis method according to one embodiment of the present invention.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Furthermore, the second lines L21, L22, L23, L24 may be connected by the switches SW11, SW12, SW13, SW14. That is, the first switch SW11 is provided between the 2-1st line L21 and the 2-2nd line L22, the second switch SW12 is provided between the 2-2nd line L22 and the 2-3rd line L23, and the third switch SW13 may be provided between the 2-3rd line L23 and the 2-4th line L24. The switches SW11, SW12, SW13 are turned on or off based on a control signal of a predetermined level, and can connect or disconnect the second lines L21, L22, L23, L24 to and from each other. That is, when the first switch SW11 is turned on, the 2-1st line L21 and the 2-2nd line L22 are connected; when the second switch SW12 is turned on, the 2-2nd line L22 and the 2-3rd line L23 are connected; and when the third switch SW13 is turned on, the 2-3rd line L23 and the 2-4th line L24 can be connected.

[0027] Figure 2 is a flowchart for explaining a method for measuring and diagnosing battery cell voltage according to an embodiment of the present invention. In addition, Figure 3 and Figure 4 are circuit diagrams for explaining the operation of the method for measuring and diagnosing battery cell voltage according to an embodiment of the present invention. That is, Figure 3 is a circuit diagram for explaining the direction of current according to the magnitude of the voltage of a battery cell to be diagnosed and the next adjacent battery cell, and Figure 4 is a circuit diagram for explaining the process of calculating the voltage across the path resistance according to the present invention.

[0028] Referring to Figure 2, the method for measuring and diagnosing battery cell voltage according to an embodiment of the present invention includes a step of 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 end of the output path (S110), and the voltage of the battery cell to be diagnosed (V BC1 ) and the voltage of the next adjacent battery cell (V BC2 ), a step of comparison (S120), 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 If it is even larger than (V BC1 >V BC2 (S130) The process involves checking whether the measured voltage across the path resistance is positive or negative (S140), determining if it is positive (S150) and if it is negative (S160) and comparing the results to determine the voltage of the battery cell being diagnosed (V BC1 ) is the voltage of the next adjacent battery cell (V BC2 If it is even smaller than (V BC1 <V BC2 The process may include checking whether the measured voltage across the path resistance is negative (S170), determining if it is a normal diagnosis if it is negative (S180), and determining if it is a diagnostic error if it is positive (S190).

[0029] Before describing the diagnostic method according to an embodiment of the present invention, the direction of current according to the voltage of two adjacent battery cells will be explained based on Figure 3. Figure 3 is a circuit diagram for illustrating the direction of current according to the voltage magnitude of the battery cell to be diagnosed and the next adjacent battery cell. Multiple battery cells BC1, BC2, BC3, and BC4 are connected, and switches SW11, SW12, SW13, and SW14 connected to the second lines L21, L22, L23, and L24 are turned on, for example, when the first and second switches SW11 and SW12 connected to the adjacent first and second battery cells BC1 and BC2 are turned on, current will flow along their respective paths. That is, the first current I11 will flow along the path of the first battery cell BC1, and the second current I12 will flow 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 and BC2. For example, if the voltage of the first battery cell BC1 is greater than the voltage of the second battery cell BC2, current will flow from the positive terminal of the first battery cell BC1 through resistor 1-1 R11, resistor 2-1 R21, and resistor 1-2 R12 to the negative terminal of the first battery cell BC1. However, if the voltage of the first battery cell BC1 is even less than the voltage of the second battery cell BC2, the current will flow in the opposite direction. Therefore, based on this principle, the present invention diagnoses the voltage measurement depending on whether the magnitude of the voltage across the path resistor is positive or negative.

[0030] The battery cell voltage measurement and diagnostic method according to this embodiment of the present invention will be explained step by step as follows.

[0031] S110: To calculate the voltage across the first path resistor, 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 I11 will flow along the path shown in Figure 3. That is, when the first switch SW11 is turned on for balancing the first battery cell BC1, the current I11 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. Needless to say, this flow of current I11 assumes that the voltage of the first battery cell BC1 is even greater than the voltage of the second battery cell BC2. At this time, a voltage drop occurs across the first-to-second resistor R12, and the voltage (V11) is measured. That is, a voltage drop occurs between node N12 and the negative terminal of the first battery cell BC1. 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, V x This is the voltage value at node N12 where line L22 branches off from line L12 of line 1-2, and the voltage value at such node N12 can be measured at measurement pin CT2 of line 1-2.

[0032]

number

[0033] In other words, the voltage across the 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 BC1 being diagnosed.

[0034] S120: Compare the voltage of the battery cell being diagnosed with the voltage of the next adjacent battery cell. For example, if the first battery cell BC1 is the battery cell being diagnosed, the voltage of the first battery cell BC1 (V BC1 ) and the voltage (V) of the second battery cell BC2 adjacent to the first battery cell BC1. BC2 Compare ) with .

[0035] S130 and S140: If the voltage of the battery cell being diagnosed is higher than that of the next adjacent battery cell (S130), the value of the voltage across the first path resistor (V11) is checked (S140). That is, it is checked whether the value of the voltage across the first path resistor (V11) is positive or not.

[0036] S150 and S160: If the voltage across the first path resistor (V11) is positive, it is diagnosed as a normal measurement (S150); if it is negative, it is diagnosed as a measurement error (S160).

[0037] S130 and S170: If the voltage of the battery cell being diagnosed is even lower than the voltage of the next adjacent battery cell (S130), check the value of the voltage across the path resistor (V11) (S170). That is, check whether the value of the voltage across the path resistor (V11) is negative.

[0038] S180 and S190: If the voltage across the path resistance (V11) is negative, it is diagnosed as a normal measurement (S180); if it is positive, it is diagnosed as a measurement error (S190).

[0039] In other words, the present invention determines the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell, V BC1 >V BC2 If so, the condition is V11>0, or V BC1 <V BC2Therefore, if the condition V11 < 0 is met, it is judged as a normal diagnosis; if neither of the two conditions is met, it is judged as a diagnostic error. In other words, if the voltage of the battery cell being diagnosed is greater than the voltage of the next adjacent 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 being diagnosed is less than the voltage of the next adjacent battery cell, it is diagnosed as a normal measurement when the resistance across the path resistance is a negative value.

[0040] Figure 5 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 5.

[0041] Referring to Figure 5, 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 cell 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 connected to a plurality of first measurement pins CT1, CT2, CT3, CT4 and a plurality of second measurement pins CB1, CB2, CB3, CB4 of a diagnostic circuit to measure voltage, a comparison unit 220 that compares the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell and compares the measured values ​​of the voltage across the path resistance based on the result, and a judgment control unit 230 that generates control signals to control switches SW1, SW12, SW13, SW14 and determines the measurement diagnostic result based on the comparison result in the comparison unit 220.

[0042] 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, and based on the measurement results, it can calculate the voltage across the path resistance (V11).

[0043] The comparison unit 220 compares the voltage of the battery cell being diagnosed with the voltage of the next adjacent battery cell. The comparison unit 220 also compares the voltage across the path resistance based on the comparison between the voltage of the battery cell being diagnosed and the voltage of the next adjacent battery cell. In other words, the comparison unit 220 calculates the voltage across the path resistance of the battery cell being diagnosed. This voltage across the path resistance can be calculated by subtracting the voltage when the battery cells are not being balanced from the voltage when the battery cells are being balanced.

[0044] The judgment control unit 230 determines the measurement diagnosis result based on the value of the voltage across the path resistor based on the comparison result in the comparison unit 220. Specifically, based on the comparison result in the comparison unit 220, 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 next adjacent battery cell and the voltage across the path resistor has a positive value, and diagnoses a measurement error if it has a negative value. Also, based on the comparison result in the comparison unit 220, 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 next adjacent battery cell and the voltage across the path resistor has a negative value, and diagnoses a measurement error if it has a positive value. In this case, if a measurement error is diagnosed, it can be determined 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 230 can control switches SW11, SW12, SW13, and SW14 by generating control signals to control them. In other words, the decision control unit 230 can select a battery cell to be diagnosed and control the switch connected to the measurement pin of that battery cell to perform balancing of that battery cell. Furthermore, the decision control unit 230 can control the switch connected to two battery cells to determine the voltage of the battery cell to be diagnosed and the voltage of the next adjacent battery cell.

[0045] As described above, the battery cell voltage measurement and diagnosis method according to one embodiment of the present invention compares the voltage of the battery cell to be diagnosed 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 a positive value, it is determined to be normal. 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 a negative value, it is determined to be normal. 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, measuring the voltage across the path resistor when balancing is not performed, and subtracting these values.

[0046] 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 voltage of the battery cell being diagnosed with the voltage of the next adjacent battery cell and determines the error based on the value of the voltage across the path resistance, 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.

[0047] 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.

[0048] The names of the reference numerals used in the description of the invention and in the drawings are as follows: [Explanation of Symbols]

[0049] 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: Comparison section 230: Decision Control Unit

Claims

1. A method for measuring and diagnosing battery cell voltage, The process of calculating the voltage across the path resistor connected to the output path of the battery cell to be diagnosed, The process involves comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell, A process for diagnosing measurement errors based on the results of the comparison and the voltage across the 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 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. A method for measuring and diagnosing the voltage of a battery cell according to claim 2, wherein 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, it is diagnosed as normal; and 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, it is diagnosed as normal.

4. A battery cell voltage measurement and diagnosis method according to claim 3, wherein, based on the result of comparing the voltage of the battery cell to be diagnosed with the voltage of the next adjacent battery cell and the value of the voltage across the path resistor, a measurement error is diagnosed in the remaining cases, excluding cases where it is diagnosed as normal.

5. A method for measuring and diagnosing the battery cell voltage of a battery pack comprising multiple battery cells and a battery management system (BMS), The process of calculating 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 said output path, The process involves comparing the voltage of the battery cell being diagnosed with the voltage of the next adjacent battery cell, and diagnosing that the measurement is normal if the comparison result and the voltage across the path resistance fall within a set value. If the aforementioned measurement is not diagnosed as normal, the process for diagnosing a voltage measurement error is as follows: A method for measuring and diagnosing battery cell voltage, including the above.

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

7. The voltage (V) of the battery cell being diagnosed ＢＣ１ ) and the voltage of the next adjacent battery cell (V ＢＣ２ ) and the voltage across the path resistor (V11) is V ＢＣ１ >V ＢＣ２ If so, when the condition V11 > 0 is met, or when the voltage of the battery cell being diagnosed (V ＢＣ１ ) and the voltage of the next adjacent battery cell (V ＢＣ２ ) and the voltage across the path resistor (V11) is V ＢＣ１ <V ＢＣ２ The battery cell voltage measurement and diagnosis method according to claim 6, wherein the condition V11 < 0 is met and the measurement is diagnosed as normal, and otherwise a measurement error is diagnosed.

Images