Battery abnormality diagnosis apparatus and method

Abstract

Disclosed is an apparatus and method of diagnosing a battery abnormality. The apparatus according to the present invention includes a control device for diagnosing a lithium precipitation abnormality of a battery. The control device can be configured to: calculate a charge capacity and a discharge capacity of a kth charge / discharge cycle; determine a capacity difference corresponding to a difference between the charge capacity and the discharge capacity; determine a kth capacity difference change amount by subtracting the capacity difference of the kth charge / discharge cycle from a capacity difference of a (k-1)th charge / discharge cycle; update an accumulated capacity difference change amount by adding the kth capacity difference change amount to the accumulated capacity difference change amount; and diagnose that a lithium precipitation abnormality occurs if the updated accumulated capacity difference change amount is greater than or equal to a threshold value.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2021-0166209, filed in Korea on November 26, 2021, and Korean Patent Application No. 10-2022-0157731, filed on November 22, 2022, the disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to a battery anomaly diagnosis device and method, and more specifically, to a battery anomaly diagnosis device and method that can accurately diagnose whether a battery is abnormal by analyzing the difference between charging capacity and discharging capacity in a time sequence, even in the presence of errors in the current sensor. Background Technology

[0003] Batteries used in electric vehicles or energy storage systems (ESS) may catch fire during use. One of the most likely causes of fire is lithium precipitation on the surface of the negative electrode.

[0004] In a normal battery, lithium ions emitted from the positive electrode must diffuse into the negative electrode during charging. However, in the case of a defective battery, some lithium ions deposit as lithium metal on the surface of the negative electrode. During repeated charging, the deposited lithium continues to grow in the form of dendrites.

[0005] Lithium deposited on the surface of the negative electrode can come into contact with the adjacent positive or negative current collector, causing an internal short circuit. This internal short circuit rapidly increases the battery's internal temperature and, in severe cases, can even lead to a fire.

[0006] Therefore, battery manufacturers are actively developing technologies for diagnosing lithium deposition.

[0007] One existing technique for diagnosing lithium deposition is based on analyzing the voltage change pattern of a battery as it enters a resting mode after charging. When a battery enters a resting mode after charging, the polarization of the electrode surfaces is depolarized, and the voltage gradually decreases until an equilibrium state is reached. However, if lithium deposition occurs during a charging cycle, lithium deposited on the surface of the negative electrode diffuses into the negative electrode when the battery enters a resting mode, and fine charging continues. Therefore, the voltage curve of a battery exhibiting lithium deposition includes an inflection point, and lithium deposition can be diagnosed by detecting the appearance of this inflection point. However, in this diagnostic technique, the inflection point can only be detected when a large amount of lithium deposition occurs during a charging cycle. That is, when the amount of lithium deposition is small, it is not easy to diagnose lithium deposition.

[0008] Furthermore, when a battery discharges, lithium exits from the negative electrode and is reinserted into the positive electrode. However, lithium deposited on the surface of the negative electrode cannot participate in this reaction, therefore the discharge capacity of a battery with lithium deposits is less than its charging capacity. Thus, lithium deposits can be diagnosed by analyzing the difference between charging and discharging capacities. However, if the charging and discharging capacities deviate from their actual values ​​due to errors in the current sensor, the diagnostic results are unreliable. For reference, when a sensing resistor is used as a current sensor, the error occurs during the amplification of the voltage applied across the sensing resistor and the conversion of the amplified voltage from an analog signal to digital data. Even if the charging and discharging currents are the same, the actual measured values ​​can differ depending on the current sensor's offset. Therefore, diagnosing lithium deposits solely based on the difference between charging and discharging capacities also has limitations. Summary of the Invention

[0009] Technical issues

[0010] This disclosure is designed to address the problems of the prior art, and therefore aims to provide a battery anomaly diagnostic apparatus and method that is robust to errors of current sensors in diagnosing lithium deposition based on the difference between charging capacity and discharging capacity.

[0011] Furthermore, this disclosure aims to provide a system or electric vehicle that includes the aforementioned battery malfunction diagnostic device.

[0012] Technical solution

[0013] In one aspect of this disclosure, a battery anomaly diagnostic device is provided, comprising: a current measuring unit configured to measure a charging current or a discharging current of a battery; and a control unit operatively connected to the current measuring unit and configured to diagnose lithium deposition anomalies while performing multiple charge / discharge cycles of the battery.

[0014] Preferably, the control unit can be configured to receive current measurement values ​​from the current measurement unit in the k-th (k is a natural number greater than or equal to 2) charge / discharge cycle to calculate the charging capacity (ChgAh[k]) and discharging capacity (DchgAh[k]), determine the capacity difference (dAh[k]) corresponding to the difference between the charging capacity (ChgAh[k]) and the discharging capacity (DchgAh[k]), determine the k-th capacity difference change (ΔdAh[k]) by subtracting the capacity difference (dAh[k]) of the k-th charge / discharge cycle from the capacity difference (dAh[k-1]) of the (k-1)-th charge / discharge cycle, update the cumulative capacity difference change by adding the k-th capacity difference change (ΔdAh[k]) to the cumulative capacity difference change, and diagnose a lithium deposition abnormality when the updated cumulative capacity difference change is greater than or equal to a threshold.

[0015] Preferably, the control unit can be configured to update the cumulative capacity difference change by adding the k-th capacity difference change (△dAh[k]) to the cumulative capacity difference change when the k-th capacity difference change (△dAh[k]) is greater than a reference value.

[0016] Preferably, the control unit can be configured to update the cumulative capacity difference change by adding the kth capacity difference change (△dAh[k]) to the cumulative capacity difference change when both the (k-1)th capacity difference change (△dAh[k-1]) and the kth capacity difference change (△dAh[k]) are greater than the reference value.

[0017] Preferably, the control unit can be configured to assign an initial value of 0 to the cumulative capacity difference when the k-th capacity difference change (ΔdAh[k]) is less than or equal to a reference value.

[0018] Preferably, the reference value can be 0.

[0019] In one implementation, when each charge / discharge cycle is performed, the control unit can be configured to perform the charging cycle within the same charging voltage range and the discharging cycle within the same discharging voltage range.

[0020] In another embodiment, when performing each charge / discharge cycle, the control unit can be configured to perform the charging cycle within the same charging voltage range and the discharging cycle under the same discharging capacity conditions.

[0021] Preferably, the battery anomaly diagnostic device according to this disclosure may further include: a display connected to the control unit, and the control unit may be configured to diagnose a lithium deposition anomaly when the cumulative capacity difference change is greater than or equal to the threshold, and output the diagnostic result through the display.

[0022] In another aspect of this disclosure, a battery anomaly diagnosis method is provided, comprising: (a) receiving current measurement values ​​from a current measurement unit in a k-th charge / discharge cycle (k being a natural number greater than or equal to 2) to calculate a charge capacity and a discharge capacity; (b) determining a capacity difference corresponding to the difference between the charge capacity and the discharge capacity; (c) determining a k-th capacity difference change by subtracting the capacity difference of the k-th charge / discharge cycle from the capacity difference of the (k-1)-th charge / discharge cycle; (d) updating a cumulative capacity difference change by adding the k-th capacity difference change to the cumulative capacity difference change; and (e) diagnosing a lithium deposition anomaly when the updated cumulative capacity difference change is greater than or equal to a threshold.

[0023] In another aspect of this disclosure, a system and an electric vehicle including the battery malfunction diagnostic device are provided.

[0024] Technical effect

[0025] According to embodiments of this disclosure, battery malfunctions can be reliably diagnosed by quantifying the likelihood of lithium deposition inside the battery using a factor called the cumulative capacity difference change, which is unaffected by current measurement errors.

[0026] According to another embodiment of this disclosure, even if there are errors between the measured values ​​of charging current and discharging current and the actual values, it is possible to reliably diagnose whether the battery is malfunctioning.

[0027] According to another embodiment of this disclosure, even if the measurement error of the charging current and the measurement error of the discharging current are different, it is possible to reliably diagnose whether the battery is abnormal.

[0028] According to another embodiment of this disclosure, the cumulative capacity difference change is calculated by integrating the capacity difference change only when the condition that the capacity difference change calculated in each charge / discharge cycle exceeds the reference value is continuously met, and when an event occurs in which the capacity difference change does not exceed the reference value, the cumulative capacity difference change is reset to 0, thereby minimizing the impact of noise.

[0029] According to yet another embodiment of this disclosure, various systems and electric vehicles including battery malfunction diagnostic devices can be provided. Attached Figure Description

[0030] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are intended to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure is not to be construed as limited to the drawings.

[0031] Figure 1 A block diagram illustrating a schematic configuration of a battery malfunction diagnostic device 10 according to an embodiment of the present disclosure.

[0032] Figures 2 to 5 This is a flowchart illustrating, specifically, the process of diagnosing lithium deposition abnormalities while the control unit repeatedly performs charge / discharge cycles according to embodiments of the present disclosure.

[0033] Figure 6 A graph showing the changes in measured data in an experimental example where the battery anomaly diagnosis method according to an embodiment of the present disclosure was applied.

[0034] Figure 7 A graph illustrating the changes in measured data in another experimental example where the battery anomaly diagnosis method according to an embodiment of the present disclosure was applied. Detailed Implementation

[0035] The preferred embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. Before this description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general and dictionary meaning, but rather as being interpreted based on the principle that the inventors are permitted to appropriately define terms for the best interpretation, and on the meaning and concept corresponding to the technical aspects of this disclosure. Therefore, the descriptions presented herein are merely preferred examples for illustrative purposes only and are not intended to limit the scope of this disclosure; thus, it should be understood that other equivalents and modifications can be made thereto without departing from the scope of this disclosure.

[0036] Figure 1 A block diagram illustrating a schematic configuration of a battery malfunction diagnostic device 10 according to an embodiment of the present disclosure.

[0037] Reference Figure 1 The battery malfunction diagnostic device 10 can diagnose lithium deposition in the battery 11 while performing multiple charge / discharge cycles.

[0038] The battery diagnostic device 10 can be a dedicated device for diagnosing the battery 11. When the battery 11 is installed in an electric vehicle, the battery diagnostic device 10 can be included in a diagnostic system provided in a repair shop for the electric vehicle. Users of the electric vehicle can periodically visit the repair shop and receive battery diagnostic services. At this time, the battery diagnostic device 10 of the diagnostic system can be connected to the battery 11 of the electric vehicle to diagnose battery abnormalities. Preferably, the abnormality is diagnosed as lithium deposition on the surface of the negative electrode of the battery 11.

[0039] Alternatively, the battery diagnostic device 10 may be included in the control elements of various systems in which the battery 11 is installed. In one example, when the battery 11 is included in an energy storage system, the diagnostic device 10 may be included in the control elements of the energy storage system (e.g., an ESS control system). In another example, when the battery 11 is included in an electric vehicle, the diagnostic device 10 may be included in the control elements of the electric vehicle (e.g., a vehicle control system).

[0040] In embodiments of this disclosure, the charge / discharge cycle includes a charge cycle and a discharge cycle.

[0041] In one example, a charging cycle means charging the battery from the lower to the upper limit of a pre-set charging voltage range while keeping the temperature of battery 11 constant, and then stopping charging. A discharging cycle means that after a charging cycle is completed, battery 11 is stabilized for a predetermined time, and while keeping the temperature of battery 11 constant in the same manner as the charging cycle, the battery is discharged from the upper to the lower limit of a pre-set discharging voltage range, and then stopping discharging. The charging voltage range and the discharging voltage range may be the same or different. However, when performing multiple charging / discharging cycles, it is preferable that the charging voltage range is the same between charging cycles, and that the discharging voltage range is also the same between discharging cycles.

[0042] In another example, a charging cycle means charging the battery from the upper to the lower limit of a preset charging voltage range while keeping the temperature of battery 11 constant, and then stopping charging. A discharging cycle means discharging starts from the upper limit of a preset discharging voltage range and stops discharging when the integral value of the discharging current reaches a preset discharging capacity. When performing multiple charging / discharging cycles, it is preferable that the charging voltage range is the same between charging cycles and the discharging capacity is the same between discharging cycles.

[0043] Battery 11 can be a lithium secondary battery, but this disclosure is not limited to battery type. Therefore, any secondary battery that can be repeatedly charged and discharged can correspond to battery 11. Battery 11 includes at least one unit cell. The unit cell can be a pouch cell, a cylindrical cell, or a prismatic cell. When multiple unit cells are present, they can be connected in series and / or in parallel.

[0044] In embodiments of this disclosure, it is assumed that battery 11 comprises a single cell or multiple cells connected in parallel. However, this disclosure is not limited to the number of cells or the electrical connections between them.

[0045] When the battery 11 comprises multiple cell units connected in series, it will be apparent to those skilled in the art that embodiments of this disclosure can be applied to diagnose abnormalities in each cell unit.

[0046] Battery 11 can be connected to load 12 to perform a discharge cycle. Load 12 may include a discharge element such as a resistor. Alternatively, load 12 consumes energy from battery 11 and may be a motor of an electric vehicle, an electrical device connected to an electrical system, or a power conversion device such as an inverter or converter.

[0047] Battery 11 can be connected to charging device 13 to perform a charging cycle. Charging device 13 can be a dedicated charging device for diagnosing abnormalities in battery 11. Alternatively, charging device 13 can be a charging station for an electric vehicle or a power conversion system (PCS) for an energy storage system. This disclosure is not limited to the type of load 12 or charging device 13.

[0048] The battery fault diagnosis device 10 may include a current measurement unit 14 for measuring the current flowing through the battery 11. The current may be a charging current or a discharging current. The current measurement unit 14 measures the current flowing through the battery 11 at regular time intervals and outputs the current measurement value to the control unit 18. Preferably, the current measurement unit 14 may be installed on the lines through which the charging and discharging currents flow.

[0049] The current measurement unit 14 can be a current measurement circuit. The current measurement unit 14 may include a Hall sensor or a sensing resistor that outputs a voltage value corresponding to the magnitude of the current. The voltage value output from the Hall sensor or the voltage value across the sensing resistor can be converted into a current value according to Ohm's law. This voltage-to-current conversion can be processed by the control unit 18. For this purpose, the control unit 18 may include an I / O interface connected to the current measurement unit 14, an amplifier circuit that amplifies the voltage signal input through the I / O interface, and an analog-to-digital converter circuit that digitizes the voltage signal output from the amplifier circuit.

[0050] The current measurement value obtained using the current measurement unit 14 may have an error compared to the actual value. In one example, when the current measurement unit 14 is a sensing resistor, the amplifier circuit that detects the voltage across the sensing resistor may have different gains depending on the direction of the current flowing through the sensing resistor. Therefore, when the current measurement unit 14 is a sensing resistor, the measured values ​​may differ even if the charging current and discharging current are the same.

[0051] The battery malfunction diagnostic device 10 may include a voltage measurement unit 15 for measuring the voltage of the battery 11. When the battery 11 is being charged or discharged, the voltage measurement unit 15 measures the voltage of the battery 11 at regular time intervals and outputs the voltage measurement value to the control unit 18. The voltage measurement unit 15 may be a voltage measurement circuit known in the art. Since voltage measurement circuits are well-known, they will not be described in detail.

[0052] The battery malfunction diagnostic device 10 may include a temperature measurement unit 16. When the battery 11 is being charged or discharged, the temperature measurement unit 16 measures the temperature of the battery 11 at regular time intervals and outputs the temperature measurement value to the control unit 18. The temperature measurement unit 16 may be a temperature measurement circuit. The temperature measurement unit 16 may include a thermocouple or temperature measuring element that outputs a voltage value corresponding to the temperature. The voltage value can be converted into a temperature value using a voltage-temperature conversion lookup table (function). The conversion from voltage value to temperature value can be processed by the control unit 18.

[0053] The battery malfunction diagnostic device 10 may include a storage unit 17. The type of storage unit 17 is not particularly limited, as long as it can record or erase data and / or information. As an example, the storage unit 17 may be RAM, ROM, a register, flash memory, a hard disk, or a magnetic recording medium.

[0054] Storage unit 17 may be electrically connected to control unit 18, for example, via a data bus to allow access by control unit 18.

[0055] Storage unit 17 stores and / or updates and / or erases and / or transmits programs including various control logics executed by control unit 18, and / or data generated when the control logic is executed and / or pre-set data, parameters, query information / tables, etc.

[0056] Preferably, the control unit 18 is operatively connected to the current measuring unit 14, the voltage measuring unit 15, the temperature measuring unit 16, and the storage unit 17.

[0057] The control unit 18 can perform multiple charge / discharge cycles while maintaining the temperature of the battery 11 at a constant set temperature in order to diagnose abnormalities in the battery 11. The control unit 18 can connect the charging device 13 to the battery 11 during the charging cycle and can connect the load 12 to the battery 11 during the discharging cycle.

[0058] Control unit 18 can be operatively coupled to temperature regulation unit 19 to maintain a constant temperature of battery 11. Temperature regulation unit 19 may include an electric heater or a fluid circulation loop. Control unit 18 can maintain the temperature of battery 11 at a set temperature by controlling temperature regulation unit 19. In one example, control unit 18 can maintain the temperature of battery 11 at a set temperature by adjusting the power of the electric heater or adjusting the temperature of the fluid supplied to the fluid circulation loop. Temperature regulation unit 19 can be coupled to battery 11 to contact the surface of battery 11.

[0059] During a charge / discharge cycle, the control unit 18 can use the current measurement unit 14 to periodically measure the amount of current flowing through the battery 11 and record the current measurement value and timestamp in the storage unit 17.

[0060] The control unit 18 can also periodically measure the voltage of the battery 11 via the voltage measurement unit 15 during the charge / discharge cycle and record the voltage measurement value and timestamp in the storage unit 17.

[0061] The control unit 18 can also periodically measure the temperature of the battery 11 during the charge / discharge cycle via the temperature measurement unit 16 and record the temperature measurement value and timestamp in the storage unit 17.

[0062] Preferably, the control unit 18 can diagnose lithium deposition abnormalities while performing multiple charge / discharge cycles on the battery 11. The number of charge / discharge cycles used to diagnose lithium deposition abnormalities can be preset. In one example, the number of charge / discharge cycles can be 20.

[0063] Figures 2 to 5 This is a flowchart illustrating, specifically, the process of diagnosing lithium deposition abnormalities while the control unit repeatedly performs charge / discharge cycles according to embodiments of the present disclosure.

[0064] Control unit 18 can be based on Figures 2 to 5 The flowchart shown in the figure executes a battery anomaly diagnosis method according to an embodiment of the present disclosure.

[0065] First, in step S10, the control unit 18 initializes the charge / discharge cycle index k to 1, and in step S20, it sets the first capacity difference change ΔdAh[1] and the first cumulative capacity difference change. Initialize each to 0.

[0066] Subsequently, in step S30, the control unit 18 begins the first charge / discharge cycle of the battery 11.

[0067] Subsequently, in step S40, the control unit 18 receives current measurement values ​​from the current measurement unit 14 during the first charge / discharge cycle and calculates the charging capacity (ChgAh[1]) and the discharging capacity (DchgAh[1]).

[0068] In step S40, the control unit 18 can control the charging device 13 to perform a charging cycle within a preset charging voltage range. Furthermore, the control unit 18 can perform a discharging cycle within a preset discharging voltage range by connecting the battery 11 to the load 12 after performing a charging cycle. The charging voltage range and the discharging voltage range can be the same or different. Preferably, the discharging cycle begins after the voltage of the battery 11 has stabilized following the completion of the charging cycle. Additionally, the discharging cycle can end when the voltage of the battery 11 reaches a preset discharging end voltage or when the integral value of the discharging current reaches a preset discharging capacity. When the start and end of the charging and discharging cycles are controlled based on voltage values, the control unit 18 can refer to the voltage measurement value of the battery 11 measured by the voltage measurement unit 15. During the charging and discharging cycles, the control unit 18 can control the temperature regulation unit 19 to maintain a constant temperature for the battery 11. Here, the temperature can be selected as any value within the operating temperature range of the battery 11.

[0069] In step S50, the control unit 18 can determine the capacity difference (dAh[1]) corresponding to the difference between the charging capacity (ChgAh[1]) and the discharging capacity (DchgAh[1]) and record the capacity difference and a timestamp in the storage unit 17. In one example, the capacity difference (dAh[1]) can be determined by subtracting the discharging capacity (DchgAh[1]) from the charging capacity (ChgAh[1]).

[0070] Then, in step S60, the control unit 18 determines whether the index k for the charge / discharge cycle is equal to n. n is preset to a natural number representing the total number of charge / discharge cycles that can be performed to diagnose lithium deposition anomalies. In one example, n can be 20. In another example, n can be a value greater than or less than 20.

[0071] If the determination is yes in step S60, the control unit 18 terminates the abnormality diagnosis process of battery 11. Conversely, if the determination is no in step S60, the control unit 18 proceeds to step S70.

[0072] In step S70, the control unit 18 begins the second charge / discharge cycle. The conditions for the second charge / discharge cycle are substantially the same as those for the first charge / discharge cycle.

[0073] Subsequently, in step S80, the control unit 18 determines the charging capacity (ChgAh[2]) and discharging capacity (DchgAh[2]) during the second charge / discharge cycle for the battery 11, and in step S90, it determines the capacity difference (dAh[2]) corresponding to the difference between the charging capacity (ChgAh[2]) and the discharging capacity (DchgAh[2]).

[0074] Then, in step S100, the control unit 18 determines the change in the second capacity difference (ΔdAh[2]) by subtracting the capacity difference of the second charge / discharge cycle (dAh[2]) from the capacity difference of the first charge / discharge cycle (dAh[1]). After step S100, the following steps are performed: Figure 3 Step S110.

[0075] Subsequently, in step S110, the control unit 18 determines whether the second capacity difference change (ΔdAh[2]) is greater than the reference value. Preferably, the reference value can be 0, but this disclosure is not limited thereto.

[0076] If the determination is yes in step S110, then in step S120, the control unit 18 adjusts the amount of change to the first cumulative capacity difference. The second capacity difference change (△dAh[2]) is added to update the cumulative capacity difference change, and the updated value is determined as the second cumulative capacity difference change. For reference, the first cumulative capacity difference change The initial value is 0.

[0077] Furthermore, if the determination is negative in step S110, then in step S130, the second capacity difference change (△dAh[2]) is not added to the first cumulative capacity difference change. And assign the initial value of 0 to the second cumulative capacity difference change.

[0078] Subsequently, in step S140, the control unit 18 determines the change in the second cumulative capacity difference. Whether it is greater than or equal to a threshold. The threshold can be set to a value suitable for diagnosing lithium deposition anomalies. In one example, the threshold can be set to 0.1% of the capacity of battery 11, but this disclosure is not limited thereto.

[0079] If the determination is yes in step S140, the control unit 18 can diagnose an abnormality in lithium deposition inside the battery 11 and output the diagnostic result through the display 20. Preferably, the diagnostic result includes a warning message indicating the occurrence of the abnormality in lithium deposition. The control unit 18 can end the diagnostic process in step S150 after outputting the diagnostic result including the warning message through the display 20.

[0080] If the determination in step S140 is negative, that is, if the change in the second cumulative capacity difference is negative... If the value is less than the threshold (or is 0), then in step S160, the control unit 18 determines whether the index k for the charge / discharge cycle is equal to n. Here, n is the total number of charge / discharge cycles that can be performed to diagnose lithium deposition abnormalities.

[0081] If the determination is yes in step S160, then since the charge / discharge cycle used to diagnose lithium deposition has been fully executed, the final diagnosis confirms that no lithium deposition abnormality has occurred inside battery 11, and the process terminates. Control unit 18 can output the final diagnostic result via display 20. The final diagnostic result may include a message indicating that no lithium deposition abnormality has occurred.

[0082] Furthermore, if the determination in step S160 is negative, the control unit 18 can also perform a charge / discharge cycle to diagnose lithium deposition abnormalities. After step S160, the following steps are executed: Figure 4 Step S180.

[0083] That is, in step S180, the control unit 18 starts the third charge / discharge cycle. The conditions of the third charge / discharge cycle are basically the same as those of the first charge / discharge cycle.

[0084] Subsequently, in step S190, the control unit 18 determines the charging capacity (ChgAh[3]) and discharging capacity (DchgAh[3]) during the third charge / discharge cycle for the battery 11, and in step S200, it determines the capacity difference (dAh[3]) corresponding to the difference between the charging capacity (ChgAh[3]) and the discharging capacity (DchgAh[3]).

[0085] Subsequently, in step S210, the control unit 18 determines the change in the third capacity difference (ΔdAh[3]) by subtracting the capacity difference of the third charge / discharge cycle (dAh[3]) from the capacity difference of the second charge / discharge cycle (dAh[2]).

[0086] Subsequently, in step S220, the control unit 18 determines whether the third capacity difference change (△dAh[3]) is greater than the reference value. Preferably, the reference value can be 0, but this disclosure is not limited thereto.

[0087] If the determination is yes in step S220, then in step S230, the control unit 18 adjusts the amount of change to the second cumulative capacity difference. The third capacity difference change (△dAh[3]) is added to update the cumulative capacity difference change, and the updated value is determined as the third cumulative capacity difference change.

[0088] Furthermore, if the determination in step S220 is negative, then in step S240, the control unit 18 does not change the amount of the second cumulative capacity difference. Add the third capacity difference change (△dAh[3]), and assign the initial value of 0 to the third cumulative capacity difference change.

[0089] After steps S230 and S240, step S250 is executed.

[0090] In step S250, the control unit 18 determines the change in the third cumulative capacity difference. Is it equal to or greater than the threshold?

[0091] If the determination is yes in step S250, then in step S260, the control unit 18 can diagnose a lithium deposition abnormality inside the battery 11 and output the diagnostic result through the display 20. Preferably, the diagnostic result includes a warning message indicating the presence of a lithium deposition abnormality. The control unit 18 can end the diagnostic process after outputting the diagnostic result including the warning message through the display 20 in step S260.

[0092] If the determination in step S250 is negative, that is, if the change in the third cumulative capacity difference is negative... If the value is less than the threshold (or is 0), then in step S270, the control unit 18 determines whether the index k for the charge / discharge cycle is equal to n. Here, n is the total number of charge / discharge cycles that can be performed to diagnose whether lithium deposition has occurred inside the battery 11.

[0093] If the determination is yes in step S270, then since the charge / discharge cycle used to diagnose lithium deposition abnormalities has been fully executed, the final diagnosis is that no lithium deposition abnormality has occurred inside battery 11, and the process terminates. Control unit 18 can output the final diagnostic result via display 20. The final diagnostic result may include a message indicating that no lithium deposition abnormality has occurred.

[0094] Furthermore, if the determination is negative in step S270, the control unit 18 can also perform a charge / discharge cycle to diagnose lithium deposition abnormalities.

[0095] The diagnostic logic for diagnosing lithium deposition anomalies, executed by the control unit 18 in the fourth charge / discharge cycle and subsequent charge / discharge cycles, is essentially the same as described above.

[0096] The following will refer to Figure 5 The process executed by the control unit 18 in the 4th to nth charge / discharge cycles is summarized and described.

[0097] In step S280, the control unit 18 begins the k-th charge / discharge cycle (k is a natural number from 4 to n). The conditions for the k-th charge / discharge cycle are basically the same as those for the first charge / discharge cycle.

[0098] Subsequently, in step S290, the control unit 18 determines the charging capacity (ChgAh[k]) and discharging capacity (DchgAh[k]) during the kth charge / discharge cycle for the battery 11, and in step S300, it determines the capacity difference (dAh[k]) corresponding to the difference between the charging capacity (ChgAh[k]) and the discharging capacity (DchgAh[k]).

[0099] Subsequently, in step S310, the control unit 18 determines the change in capacity difference (ΔdAh[k]) by subtracting the capacity difference (dAh[k]) of the kth charge / discharge cycle from the capacity difference (dAh[k-1]) of the (k-1)th charge / discharge cycle.

[0100] Subsequently, in step S320, the control unit 18 determines whether the change in the k-th capacity difference (ΔdAh[k]) is greater than a reference value. Preferably, the reference value can be 0, but this disclosure is not limited thereto.

[0101] If the determination is yes in step S320, then in step S330, the control unit 18 adjusts the cumulative capacity difference by adjusting the amount of change to the (k-1)th cumulative capacity difference. The cumulative capacity difference change is updated by adding the k-th capacity difference change (ΔdAh[k]), and the updated value is determined as the k-th cumulative capacity difference change.

[0102] Furthermore, if the determination in step S320 is negative, then in step S340, the control unit 18 does not adjust the cumulative capacity difference for the (k-1)th time step. Add the k-th capacity difference change (ΔdAh[k]), and assign the initial value of 0 to the k-th cumulative capacity difference change.

[0103] After steps S330 and S340, step S350 is executed.

[0104] In step S350, the control unit 18 determines the change in the k-th cumulative capacity difference. Is it greater than or equal to the threshold?

[0105] If the determination is yes in step S350, then in step S360, the control unit 18 can diagnose a lithium deposition abnormality inside the battery 11 and output the diagnostic result through the display 20. Preferably, the diagnostic result includes a warning message indicating the presence of a lithium deposition abnormality. In step S360, the control unit 18 can output the diagnostic result including the warning message through the display 20, and then terminate the diagnostic process.

[0106] If the determination in step S350 is negative, that is, if the change in the k-th cumulative capacity difference is negative... If the value is less than the threshold (or is 0), then in step S370, the control unit 18 determines whether the index k for the charge / discharge cycle is equal to n. Here, n is the total number of charge / discharge cycles that can be performed to diagnose whether lithium deposition has occurred inside the battery 11.

[0107] If the determination is yes in step S370, then since the charge / discharge cycle used to diagnose lithium deposition has been fully executed, the final diagnosis confirms that no lithium deposition abnormality has occurred inside battery 11, and the process terminates. Control unit 18 can output the final diagnostic result via display 20. The final diagnostic result may include a message indicating that no lithium deposition abnormality has occurred.

[0108] Furthermore, if the determination in step S370 is negative, the control unit 18 increments the index k of the charge / discharge cycle by 1 to further execute the charge / discharge cycle in order to diagnose lithium deposition abnormalities, and then returns the process to S280. Thus, steps S280 to S370 are repeated periodically until the index k of the charge / discharge cycle becomes n.

[0109] According to an embodiment of this disclosure, when the capacity difference change calculated in the current charge / discharge cycle is less than or equal to a reference value, the cumulative capacity difference change calculated up to the previous cycle is initialized to 0. Furthermore, if the capacity difference change calculated in the current charge / discharge cycle is greater than the reference value, the current capacity difference change is added to the previous cumulative capacity difference change. As a result, the cumulative capacity difference change increases. The previous cumulative capacity difference change was 0 or a positive value. If the cumulative capacity difference change is positive, the capacity difference changes calculated in consecutive charge / discharge cycles that are greater than the reference value are accumulated. Furthermore, while the capacity difference change is accumulated, if the capacity difference change decreases to or below the reference value in a specific charge / discharge cycle, the cumulative capacity difference change is initialized to 0. By applying this logic, the cumulative capacity difference change can be considered a quantitative indicator for measuring lithium deposition anomalies. That is, if the capacity difference change is greater than the reference value, it means that lithium deposition is possible. Furthermore, if the capacity difference change exceeds a reference value consecutively across multiple sequential charge / discharge cycles, and the cumulative capacity difference change increases to a threshold or above, this implies a correspondingly high probability of lithium deposition. The technical significance of this disclosure lies in using a factor known as the cumulative capacity difference change to quantify the probability of lithium deposition.

[0110] Figure 6 A graph showing the changes in measured data in an experimental example where the battery anomaly diagnosis method according to an embodiment of the present disclosure was applied.

[0111] In this experimental example, a pouch-type lithium polymer battery was used. The lithium polymer battery selected for the experiment was degraded and in a state where lithium had begun to deposit on the negative electrode. The current capacity of the lithium polymer battery, reflecting the degree of degradation, was approximately 50 Ah. The charging conditions for the charging cycle were CC (constant current) - CV (constant voltage) charging. CC charging was terminated when the target CC charging voltage was reached, and charging was switched to CV charging. Charging was terminated when the CV charging current reached the target current. The discharging conditions for the discharging cycle were CC discharging, and discharging was terminated when a given discharge capacity was achieved. The temperature conditions for the charging and discharging cycles were 45°C. A reference value of 0 was used as a standard for determining whether the integral capacity difference change was significant, and a threshold of 0.06 Ah was set as a standard for diagnosing abnormal lithium deposition.

[0112] A sensing resistor is used as the current measurement unit 14. The analog voltage measured across the sensing resistor is input to the I / O interface of the control unit 18. The control unit 18 includes circuitry that amplifies the voltage signal input through the I / O interface and converts the amplified analog signal into a digital signal. A difference (offset) exists between the current value measured by this circuitry and the actual current value. In this experimental example, the measured discharge current has a larger error than the actual value. Therefore, according to the charge / discharge cycle index, the discharge capacity can be greater than the charge capacity.

[0113] Figure ① shows the measurement results of the charging capacity (ChgAh[k]) and discharging capacity (DchgAh[k]) for each charge / discharge cycle. The charging capacity (ChgAh[k]) and discharging capacity (DchgAh[k]) are calculated by integrating the current value measured by the sensing resistor. Due to errors in the discharge current measurement, the discharge capacity is greater than the charging capacity from the 4th discharge cycle onwards.

[0114] Figure ② shows the capacity difference (dAh[k]) for each charge / discharge cycle. As shown in Figure ①, since the discharge capacity is greater than the charge capacity from the 4th charge / discharge cycle onwards, the capacity difference (dAh[k]) becomes negative from the 4th cycle onwards.

[0115] Figure ③ shows the change in capacity difference (ΔdAh[k]) for each charge / discharge cycle. The indices of charge / discharge cycles with positive change in capacity difference (ΔdAh[k]) are 2 to 13, 17 to 18, and 20. The indices of charge / discharge cycles with negative change in capacity difference (ΔdAh[k]) are 14 to 16 and 19.

[0116] Figure 4 shows the cumulative capacity difference change for each charge / discharge cycle. The graph shows that the indices of charge / discharge cycles where the capacity difference change (ΔdAh[k]) is positive are 2 to 13. Therefore, as the capacity difference change (ΔdAh[k]) is accumulated from the second to the thirteenth charge / discharge cycles, the cumulative capacity difference change... Increase. Furthermore, when the capacity difference change over the thirteenth charge / discharge cycle is accumulated, the accumulated capacity difference change... The threshold of 0.06 Ah was exceeded. Therefore, the thirteenth charge / discharge cycle was executed, the control unit 18 diagnosed an abnormality of lithium deposition inside the battery, output the diagnostic result through the display 20, and terminated the diagnostic process. Since lithium was deposited on the negative electrode of the lithium polymer battery used in this experiment, it can be seen that the diagnostic accuracy of this disclosure is high.

[0117] Figure 7A graph illustrating the changes in measured data in another experimental example where the battery anomaly diagnosis method according to an embodiment of the present disclosure was applied.

[0118] exist Figure 7 In this example, Figure ① is the same as Figure ① in the experimental example described above. Figure ①' shows the measurement results of charging capacity (ChgAh[k]) and discharging capacity (DchgAh[k]) when using a current measurement unit with a current measurement error different from that in the experimental example described above. In this experimental example, the error in the discharge current measurement is greater than that in the experimental example described above. Therefore, the graph of discharge capacity (DchgAh[k]) is shifted upwards compared to the experimental example described above.

[0119] Figures 2 and 2' show the capacity difference (dAh[k]) for each charge / discharge cycle, Figures 3 and 3' show the change in capacity difference (ΔdAh[k]) for each charge / discharge cycle, and Figures 4 and 4' show the cumulative change in capacity difference for each charge / discharge cycle. The image.

[0120] Figures 2, 3, and 4 are calculated using the data from Figure 1, while Figures 2', 3', and 4' are calculated using the data from Figure 1'.

[0121] As shown in Figure 7, Figures ②, ③, and ④, as well as Figures ②', ③', and ④', are essentially the same. Therefore, even if the discharge current value has a measurement error, the control unit 18 executes the thirteenth charge / discharge cycle regardless of the magnitude of the error, then diagnoses the lithium deposition anomaly inside the battery, outputs the diagnostic result to the display 20, and terminates the diagnostic process. From these experimental results, it can be seen that this disclosure can reliably diagnose lithium deposition anomalies regardless of errors in current measurement values.

[0122] Preferably, the battery malfunction diagnostic device 10 according to embodiments of the present disclosure can be included in a diagnostic system for diagnosing whether the battery 11 is malfunctioning. The diagnostic system can be operated by an electric vehicle repair shop, battery manufacturer, or battery repair company.

[0123] Preferably, the diagnostic system can be used to diagnose anomalies in batteries installed in electric vehicles or energy storage systems, or to diagnose anomalies in newly developed battery models manufactured by battery manufacturers. In particular, in the latter case, before the newly developed battery model is commercialized, the battery anomaly diagnostic device 10 can be used to check whether the battery contains structural defects that lead to lithium deposition.

[0124] Alternatively, the battery malfunction diagnostic device 10 may be included in the control element of the system in which the battery 11 is installed.

[0125] In one example, the battery anomaly diagnostic device 10 can be included in the control system of an electric vehicle. In this case, the battery anomaly diagnostic device 10 can collect data related to the battery's charging and discharging capacity during the charging and discharging process of the battery installed in the electric vehicle, use the collected data to diagnose lithium deposition anomalies, and output the diagnostic results to the integrated control display of the electric vehicle.

[0126] In this disclosure, electric vehicle refers to a motor-driven vehicle such as an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. The vehicle may be two-wheeled, three-wheeled, or four-wheeled.

[0127] In another example, the battery anomaly diagnostic device 10 can be included in the control system of the energy storage system. In this case, the battery anomaly diagnostic device 10 can collect data related to the battery's charging and discharging capacity during the charging and discharging process of the energy storage system, use the collected data to diagnose lithium deposition anomalies, and output the diagnostic results through a display of an operator-accessible integrated management computer.

[0128] When a diagnostic result indicating lithium deposition anomaly is displayed, the electric vehicle user or the energy storage system operator can take appropriate safety measures. In one example, the electric vehicle user can visit a repair shop for inspection. In another example, the energy storage system operator can replace the corresponding battery with a new one.

[0129] In this disclosure, the control unit 18 may be a control circuit. The control unit 18 may optionally include processors, application-specific integrated circuits (ASICs), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., known in the art, to execute the various control logics described above. Furthermore, when the control logic is implemented as software, the control unit 18 may be implemented as a collection of program modules. In this case, the program modules may be stored in memory and executed by the processor. The memory may be located inside or outside the processor and may be connected to the processor via various known computer components. Furthermore, the memory may be included in the storage unit 17 of this disclosure. Moreover, memory generally refers to a device for storing information regardless of the type of device, and does not refer to a specific memory device.

[0130] One or more of the various control logics of the control unit 18 are combined, and the combined control logic can be written in a computer-readable code system and recorded on a computer-readable recording medium. The type of recording medium is not particularly limited, as long as it can be accessed by a processor included in a computer. As an example, the recording medium includes at least one selected from the group consisting of ROM, RAM, registers, CD-ROM, magnetic tape, hard disk, floppy disk, and optical data recording devices. Furthermore, the code system can be distributed, stored, and executed in a computer connected via a network. Moreover, the functional programs, code, and code segments used to implement the combined control logic can be readily derived by a programmer in the art to which this disclosure pertains.

[0131] In describing the various embodiments of this disclosure, elements designated as "...units" should be understood as functionally distinct elements, not physically distinct elements. Thus, each component can be selectively integrated with other components, or each component can be divided into sub-components for efficient execution of control logic. However, it will be apparent to those skilled in the art that even if components are integrated or divided, if the same function can be identified, the integrated or divided components should be interpreted as falling within the scope of this disclosure.

[0132] This disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of this disclosure, are provided by way of illustration only, as various changes and modifications within the scope of this disclosure will become apparent to those skilled in the art from this detailed description.

Claims

1. A battery anomaly diagnostic device, the battery anomaly diagnostic device comprising: A current measuring unit, configured to measure the charging current or discharging current of a battery; as well as A control unit, operably coupled to the current measurement unit, is configured to diagnose lithium deposition anomalies while performing multiple charge / discharge cycles of the battery. The control unit is configured to receive current measurement values ​​from the current measurement unit in the k-th charge / discharge cycle to calculate the charging capacity and the discharging capacity, determine the capacity difference corresponding to the difference between the charging capacity and the discharging capacity, determine the k-th capacity difference change by subtracting the capacity difference of the k-th charge / discharge cycle from the capacity difference of the (k-1)-th charge / discharge cycle, update the cumulative capacity difference change by adding the k-th capacity difference change to the cumulative capacity difference change, and diagnose a lithium deposition abnormality when the updated cumulative capacity difference change is greater than or equal to a threshold, where k is a natural number greater than or equal to 2.

2. The battery malfunction diagnostic device according to claim 1, in, The control unit is configured to update the cumulative capacity difference change by adding the kth capacity difference change to the cumulative capacity difference change when the kth capacity difference change is greater than a reference value.

3. The battery malfunction diagnostic device according to claim 1, in, The control unit is configured to update the cumulative capacity difference change by adding the kth capacity difference change to the cumulative capacity difference change when both the (k-1)th capacity difference change and the kth capacity difference change are greater than a reference value.

4. The battery malfunction diagnostic device according to claim 1, in, The control unit is configured to assign an initial value of 0 to the cumulative capacity difference when the k-th capacity difference change is less than or equal to a reference value.

5. The battery malfunction diagnostic device according to any one of claims 2 to 4, in, The reference value is 0.

6. The battery malfunction diagnostic device according to claim 1, wherein, The threshold is set to 0.1% of the battery's capacity.

7. The battery malfunction diagnostic device according to claim 1, in, When each charge / discharge cycle is performed, the control unit is configured to perform the charging cycle within the same charging voltage range and the discharging cycle within the same discharging voltage range.

8. The battery malfunction diagnostic device according to claim 1, in, When each charge / discharge cycle is performed, the control unit is configured to perform the charge cycle within the same charging voltage range and the discharge cycle under the same discharge capacity conditions.

9. The battery anomaly diagnostic device according to claim 1, further comprising: A display, which is connected to the control unit. The control unit is configured to diagnose lithium deposition abnormality when the cumulative capacity difference change is greater than or equal to the threshold, and to output the diagnostic result through the display.

10. A system comprising a battery malfunction diagnostic device according to any one of claims 1 to 9.

11. An electric vehicle comprising a battery malfunction diagnostic device according to any one of claims 1 to 9.

12. A battery anomaly diagnosis method, wherein the battery anomaly diagnosis method diagnoses whether the battery is abnormal by performing multiple charge / discharge cycles of the battery, the battery anomaly diagnosis method comprising the following steps: (a) Receive current measurement values ​​from the current measurement unit in the kth charge / discharge cycle to calculate the charging capacity and discharging capacity, where k is a natural number greater than or equal to 2; (b) Determine the capacity difference corresponding to the difference between the charging capacity and the discharging capacity; (c) The change in capacity difference of the kth charge / discharge cycle is determined by subtracting the capacity difference of the kth charge / discharge cycle from the capacity difference of the (k-1)th charge / discharge cycle; (d) Update the cumulative capacity difference change by adding the k-th capacity difference change to the cumulative capacity difference change; and (e) When the updated cumulative capacity difference change is greater than or equal to the threshold, an abnormality in lithium deposition is diagnosed.

13. The battery anomaly diagnosis method according to claim 12, in, In step (d), when the change in the kth capacity difference is greater than the reference value, the cumulative capacity difference change is updated by adding the change in the kth capacity difference to the cumulative capacity difference change.

14. The battery anomaly diagnosis method according to claim 12, in, In step (d), when both the (k-1)th capacity difference change and the kth capacity difference change are greater than the reference value, the cumulative capacity difference change is updated by adding the kth capacity difference change to the cumulative capacity difference change.

15. The battery anomaly diagnosis method according to claim 12, further comprising the following steps: When the kth capacity difference change is less than or equal to the reference value, the initial value 0 is assigned to the cumulative capacity difference change.

16. The battery anomaly diagnosis method according to any one of claims 13 to 15, in, The reference value is 0.

17. The battery anomaly diagnosis method according to claim 12, in, The threshold is set to 0.1% of the battery's capacity.

18. The battery anomaly diagnosis method according to claim 12, in, In step (a), when each charge / discharge cycle is performed, the charging cycle is performed within the same charging voltage range, and the discharging cycle is performed within the same discharging voltage range.

19. The battery anomaly diagnosis method according to claim 12, in, In step (a), when each charge / discharge cycle is performed, the charging cycle is performed within the same charging voltage range, and the discharging cycle is performed under the same discharging capacity conditions.

20. The battery anomaly diagnosis method according to claim 12, further comprising the following steps: When the cumulative capacity difference increases to a level greater than or equal to the threshold, a lithium deposition abnormality is diagnosed, and the diagnostic result is output to the display.

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