Overheating diagnostic method, overheating diagnostic device and battery system that provide the method

Abstract

The overheating diagnostic method, and the overheating diagnostic device and battery system that provide the method, relate to the overheating diagnostic device of the present invention, which includes a measurement unit that measures the temperature of an object, a storage unit that stores the temperature values ​​measured by the measurement unit, and a control unit that, for each diagnostic time point at which overheating of the object is diagnosed, extracts a plurality of previous diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average that is the average of the plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation average that is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and if an error value calculated by multiplying the standard deviation average by a predetermined multiple is equal to or greater than a predetermined error reference value, adds the error value to the moving average to calculate an overheating reference value, and compares the temperature value measured at each diagnostic time point with the overheating reference value calculated for each diagnostic time point to diagnose the occurrence of an overheating event for the object.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0185631, filed December 27, 2022, and Korean Patent Application No. 10-2023-0185646, filed December 19, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a method for diagnosing overheating in an object (for example, a battery), an overheating diagnostic device that provides the method, and a battery system. [Background technology]

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically and the development of electric vehicles, energy storage batteries, robots, and artificial satellites has progressed in earnest, research into high-performance batteries that can be repeatedly charged and discharged is actively underway.

[0004] Currently available commercial batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention due to their advantages over nickel-based batteries, such as almost no memory effect, freedom in charging and discharging, a very low self-discharge rate, and high energy density.

[0005] Meanwhile, battery temperature is a factor that has a significant impact on battery performance. Generally, a battery can operate efficiently when its temperature is properly distributed. For example, if the battery temperature is excessively high, the stability of the battery's negative electrode crystal lattice may be reduced, resulting in a decrease in battery performance or even an explosion. Therefore, it is necessary to accurately monitor the battery temperature.

[0006] In the past, the presence or absence of battery overheating was diagnosed by comparing the measured battery temperature with a preset reference value. However, the conventional method has a problem that it is difficult to take appropriate measures because the time interval between the diagnosis of an overheating event and the occurrence of a battery explosion is too short. In addition, the conventional method has a problem of misdiagnosing a temperature increase due to battery aging as an overheating event. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention relates to an overheat diagnostic method capable of diagnosing abnormal heat generation behavior (hereinafter referred to as overheating) of an object with high accuracy, an overheat diagnostic device that provides the method, and a battery system. [Means for solving the problem]

[0008] An overheating diagnosis device according to one aspect of the present invention includes a measurement unit that measures the temperature of an object, a storage unit that stores the temperature values ​​measured by the measurement unit, and a control unit that, for each diagnosis time point at which overheating of the object is diagnosed, extracts a plurality of previous diagnosis time points corresponding to a predetermined number of samples based on the diagnosis time point, calculates a moving average that is the average of the plurality of temperature values ​​corresponding to each of the plurality of diagnosis time points, calculates a standard deviation average that is the average of a plurality of standard deviations corresponding to each of the plurality of diagnosis time points, and if an error value calculated by multiplying the standard deviation average by a predetermined multiple is equal to or greater than a predetermined error reference value, adds the error value to the moving average to calculate an overheating reference value, and compares the temperature values ​​measured at each diagnosis time point with the overheating reference value calculated for each diagnosis time point to diagnose the occurrence of an overheating event for the object.

[0009] If the error value is less than the error reference value, the control unit can correct the temperature values ​​according to the results of comparing each of the temperature values ​​corresponding to the diagnostic time points with the moving average value, and calculate the overheating reference value based on the corrected temperature values.

[0010] For each of the plurality of temperature values, if the temperature value is equal to or greater than the moving average value, the control unit can add a predetermined correction value to the temperature value, and if the temperature value is less than the moving average value, can subtract the correction value from the temperature value to correct the temperature value.

[0011] If the measured temperature value exceeds the overheat reference value, the control unit can diagnose that an overheat event has occurred in the object.

[0012] According to another aspect of the present invention, a battery system includes a battery including a plurality of battery cells, a measurement unit that measures the temperature of the battery, a storage unit that stores the temperature values ​​measured by the measurement unit, and a control unit that, for each diagnostic time point at which overheating of the battery is diagnosed, extracts a plurality of diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average that is an average of the plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation average that is an average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and if an error value calculated by multiplying the standard deviation average by a predetermined multiple is equal to or greater than a predetermined error reference value, adds the error value to the moving average to calculate an overheating reference value, and compares the temperature value measured at each diagnostic time point with the overheating reference value calculated for each diagnostic time point to diagnose the occurrence of an overheating event in the battery.

[0013] If the error value is less than the error reference value, the control unit can correct the temperature values ​​according to the results of comparing each of the temperature values ​​corresponding to the diagnostic time points with the moving average value, and calculate the overheating reference value based on the corrected temperature values.

[0014] For each of the plurality of temperature values, if the temperature value is equal to or greater than the moving average value, the control unit can add a predetermined correction value to the temperature value, and if the temperature value is less than the moving average value, can subtract a predetermined correction value from the temperature value to correct the temperature value.

[0015] If the measured temperature value exceeds the overheat reference value, the control unit can diagnose that an overheat event has occurred in the battery.

[0016] According to another aspect of the present invention, an overheat diagnosis method includes a temperature data collecting step of receiving a temperature value, which is a temperature measurement value of the battery, from a measurement unit at a predetermined diagnosis time point for diagnosing overheating of a battery including a plurality of battery cells; a sample group determining step of extracting a plurality of previous diagnosis time points corresponding to a sample number based on the diagnosis time point; an overheat reference value calculating step including a step of calculating a moving average which is an average of a plurality of temperature values ​​corresponding to each of the plurality of diagnosis time points; a step of calculating a standard deviation average which is an average of a plurality of standard deviations corresponding to each of the plurality of diagnosis time points and multiplying the standard deviation average by a predetermined multiple to calculate an error value; and an overheat diagnosis step of comparing the temperature value with the overheat reference value to diagnose an occurrence of an overheating event in the battery.

[0017] The overheat reference value calculation step may further include a temperature value correction step of correcting the plurality of temperature values ​​corresponding to the plurality of diagnostic time points according to a comparison result between each of the plurality of temperature values ​​and the moving average value if the error value is less than the error reference value, and the overheat reference value calculation step may calculate the overheat reference value based on the corrected plurality of temperature values.

[0018] The temperature value correction step may include a step of extracting a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, a step of comparing each of the plurality of temperature values ​​with the moving average value, a first correction step of correcting the temperature value by adding a predetermined correction value to the temperature value if the temperature value is equal to or greater than the moving average value as a result of the comparison, and a second correction step of correcting the temperature value by adding a predetermined correction value to the temperature value if the temperature value is less than the moving average value.

[0019] The overheating diagnosis step may include a first diagnosis step of comparing the measured temperature value with the overheating reference value, diagnosing that an overheating event has occurred in the battery if the measured temperature value exceeds the overheating reference value as a result of the comparison, and a second diagnosis step of diagnosing that an overheating event has not occurred in the battery and that the battery is in a normal state if the measured temperature value is equal to or less than the overheating reference value as a result of the comparison. [Effects of the Invention]

[0020] Unlike conventional methods that use a fixed reference value for diagnosis, the present invention calculates an overheating reference value that reflects the temperature trend of the object at each time of overheating diagnosis, and performs overheating diagnosis by comparing the calculated overheating reference value with the measured temperature, thereby making it possible to accurately determine whether an overheating event has occurred.

[0021] The present invention can prevent the problem of misdiagnosing a temperature rise due to aging of an object (e.g., a battery) as the occurrence of an overheating event by calculating an overheating reference value based on a moving average value and a standard deviation for each diagnostic point in time.

[0022] The present invention can significantly improve the accuracy of diagnosis by correcting the multiple temperature values ​​that form the basis for calculating the overheating reference value when the interval between the overheating reference value and the moving average value is significantly narrow. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram illustrating an overheat diagnostic device according to an embodiment. [Figure 2] FIG. 10 is a block diagram illustrating a battery system according to another embodiment. [Figure 3] 4 is a flowchart illustrating an overheating diagnosis method according to an embodiment. [Figure 4] 4 is a flowchart illustrating in detail the overheat reference value calculation step S300 of FIG. 3. [Figure 5] 5 is a flowchart illustrating in detail the temperature value correction step S370 of FIG. 4. [Figure 6] FIG. 10 is an exemplary diagram showing the temperature change of a non-defective battery in a charging mode. [Figure 7] FIG. 10 is an exemplary diagram showing the temperature change of a defective battery in charging mode. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by the same or similar drawing numbers, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" for components used in the following description are given or used interchangeably solely for the convenience of writing the specification, and do not have any distinct meanings or functions. Furthermore, when describing the embodiments disclosed herein, if it is determined that a detailed description of such known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are merely intended to facilitate understanding of the embodiments disclosed herein, and the technical concepts disclosed herein are not limited by the accompanying drawings, and all modifications, equivalents, or alternatives within the concept and technical scope of the present invention are to be understood.

[0025] Terms including ordinal numbers such as first, second, etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0026] When a component is referred to as being "coupled" or "connected" to another component, it is understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is referred to as being "directly coupled" or "directly connected" to another component, it is understood that there are no other components in between.

[0027] It should be understood that in this application, the use of terms such as "comprise" or "have" is intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof stated in the specification, but does not preclude the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0028] FIG. 1 is a block diagram illustrating an overheat diagnostic device according to one embodiment.

[0029] Referring to FIG. 1, the overheat diagnostic device 1 includes a measurement unit 11, a storage unit 13, and a control unit 15.

[0030] The measurement unit 11 can measure the temperature of an object at each time point (hereinafter, referred to as a diagnosis time point) when diagnosing overheating of the object, and transmit the measurement result to the control unit 15. For example, the measurement unit 11 can include a temperature sensor that measures the temperature of the object. In this case, the object can include, but is not limited to, a battery, and can include various devices that need to be predicted in advance before an overheating event occurs.

[0031] The storage unit 13 can store the temperature value of the object measured by the measurement unit 11 for each diagnostic time point. The storage unit 13 can also store the moving average (MA), standard deviation (SD), standard deviation average (SD_ave), and overheating reference value (Th) calculated by the control unit 15 for each diagnostic time point. For example, the temperature value (T), moving average (MA), standard deviation (SD), standard deviation average (SD_ave), and overheating reference value (Th) of the object corresponding to a predetermined diagnostic time point may be stored in the storage unit 13 in the form of a lookup table.

[0032] When a diagnosis time point based on a preset condition arrives, the control unit 15 calculates a moving average value (MA) and an overheating reference value (Th) that is greater than the moving average value by a predetermined value. For example, if the object is a battery, the diagnosis time point may be the time point when charging of the battery starts or the time point when discharging of the battery ends. However, the diagnosis time point is not limited to this, and various other settings are possible.

[0033] First, the control unit 15 may determine a sample group by extracting a plurality of diagnostic time points included in a predetermined number of samples (SN) when counting diagnostic time points from the current diagnostic time point (N) toward the previous diagnostic time point. Here, the number of samples (SN) is the number of diagnostic time points included in the sample group, and may be determined to be an optimal number based on experiments, etc.

[0034] The sample population is a subpopulation of a plurality of past diagnosis points that is the parent population, and may be a population for calculating a moving average (MA) and a standard deviation average (SD_ave), which will be described below.

[0035] [Table 1]

[0036] Table 1 above is an example of a lookup table for the temperature value (T), moving average (MA), standard deviation (SD), standard deviation average (SD_ave), error value (ER), and overheating reference value (Th) of an object corresponding to each of a plurality of diagnosis points. Hereinafter, the overheating reference value (Th) required for overheating diagnosis at the Nth diagnosis point will be referred to as N ) will be described in detail. Also, the sample number (SN) is assumed to be 5. However, the sample number (SN) is not limited to this and can be determined to be various positive integers.

[0037] For reference, in Table 1, at the initial diagnostic time point (1), there are no previous diagnostic time points that constitute the sample population, so it may be difficult to directly calculate the moving average (MA), standard deviation (SD), standard deviation average (SD_ave), and overheating reference value (Th) (therefore, the corresponding values ​​in Table 1 are displayed as blanks). Furthermore, at certain diagnostic time points (e.g., 2, 3, 4, 5) adjacent to the initial diagnostic time point (1), there are insufficient numbers of multiple previous diagnostic time points that constitute the sample population, so it may be difficult to calculate the moving average (MA), standard deviation (SD), standard deviation average (SD_ave), and overheating reference value (Th). In this case, the designer can provide values ​​calculated by averaging through experiments as the moving average (MA), standard deviation (SD), standard deviation average (SD_ave), and overheating reference value (Th) at the initial diagnostic time point and adjacent diagnostic time points (e.g., 1, 2, 3, 4, 5).

[0038] When counting diagnostic time points in the forward direction based on the Nth diagnostic time point (N), which is the current diagnostic time point, the control unit 15 can extract the N-1st diagnostic time point, the N-2nd diagnostic time point, the N-3rd diagnostic time point, the N-4th diagnostic time point, and the N-5th diagnostic time point, which correspond to five sample numbers (SN), to determine the sample group.

[0039] The control unit 15 extracts a plurality of diagnostic time points (N-1, N-2, N-3, N-4, N-5) to determine a sample group, and determines an overheating reference value (Th) to be used for overheating diagnosis based on the temperature values ​​measured at each of the plurality of diagnostic time points (N-1, N-2, N-3, N-4, N-5) belonging to the sample group. N ) can be calculated.

[0040] For example, if the object is a battery, the internal resistance of the battery increases with prolonged use, and the temperature may increase gradually due to the increase in the internal resistance. NWhen diagnosing battery overheating based on the above, it is possible to prevent the problem of misdiagnosing a temperature rise due to long-term use as an overheating event, and also to solve the problem of misdiagnosing a temporary temperature rise as an overheating event.

[0041] Next, the control unit 15 calculates the overheat reference value (Th) corresponding to the Nth diagnostic time point based on the temperature values ​​(T) measured at each of the multiple diagnostic time points (N-1, N-2, N-3, N-4, N-5) belonging to the sample group. N ) is calculated.

[0042] According to one embodiment, the control unit 15 may calculate the temperature value (T N ) is the overheating reference value (Th N ) to diagnose whether the object is overheating. For example, referring to Table 1, N ) and standard deviation mean (SD N _ave) is the overheat reference value (Th N ) is the value required to calculate the standard deviation (SD N ) is not a value required when diagnosing an overheating state at the Nth diagnostic time point, but is required for determining an overheating event at later diagnostic time points (N+1, N+2, ...), so it may be calculated at the Nth diagnostic time point and stored in the storage unit 13.

[0043] Referring to Table 1, the moving average value (MA) calculated by the control unit 15 at the time of the Nth diagnosis is as follows: N ), standard deviation (SD N ), mean standard deviation (SD N _ave), error value (ER N ) and overheating reference value (Th N ) is explained.

[0044] The control unit 15 calculates the average (29.4°C + 29.3°C + 29.4°C + 29.3°C + 29.5°C / 5 = 29.38°C) of the multiple temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) corresponding to the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population, and calculates the moving average (MA) corresponding to the Nth diagnostic time point (N).N , 29.38℃) can be calculated. N ) can be calculated using the following formula (1). MA N =(T N-5 +T N-4 +T N-3 +T N-2 +T N-1 ) / N (1)

[0045] Referring to Table 1 and Table 2 below, the control unit 15 calculates the temperature values ​​(T) corresponding to each of the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample group, and the moving average value (MA) corresponding to the Nth diagnostic time point (N). N ) based on the standard deviation (SD) corresponding to the Nth diagnosis time point. N ) can be calculated.

[0046] [Table 2]

[0047] As explained above, the standard deviation (SD) corresponding to the Nth diagnosis time point N ) is not a value required for diagnosing an overheating state at the Nth diagnostic point in time, but is required for diagnosing whether an overheating event has occurred in the object at later diagnostic points in time (N+1, N+2, ...). Therefore, the standard deviation (SD N ) may be calculated at the Nth diagnosis time point and stored in the storage unit 13.

[0048] [Table 3]

[0049] Referring to Tables 1 and 3, the control unit 15 calculates a plurality of standard deviations (SD) corresponding to the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population. N-5 , S.D. N-4 , S.D. N-3 , S.D. N-2 , S.D.N-1 ) based on the standard deviation mean (SD N _ave, 0.07442) can be calculated.

[0050] The control unit 15 calculates the moving average value (MA N ) is greater than the specified value. N First, the control unit 15 calculates the standard deviation average value (SD N _ave) is multiplied by a preset factor (α) to obtain the error value (ER N ) can be calculated. In this case, the multiple (α) is a value that reflects various errors and can be determined to various values ​​through experiments. Hereinafter, the multiple (α) is assumed to be the natural number 3 (α=3). ER N =SD N _ave×α (2)

[0051] For example, referring to Table 3 and Equation (2), the control unit 15 calculates the standard deviation average value (SD N _ave=0.07442) is multiplied by a factor (α=3) to obtain the error value (ER N )0.22326 can be calculated.

[0052] Error value (ER N ) is a value that reflects the error that can occur in various situations, such as temperature measurement. N ) is very small, the moving average (MA N ) and overheating reference value (Th N ) may be very close to the temperature measured at the Nth diagnostic point, even though no overheating event has actually occurred. N ) is the overheating reference value (Th N ) can result in a false diagnosis of an overheating event. N If the error value (ER) on which the calculation of ) is based is smaller than the generally expected value, there is a high possibility of misdiagnosis occurring.

[0053] According to one embodiment, the error value (ER N ) is the predetermined error standard value (TH N If the moving average value (MA N ) to the error value (ER N ) is added to the overheat reference value (Th N ) can be calculated. Below, the error standard value (TH N _ER) is the moving average (MA N ) (29.38°C x 0.01 = 0.2938), but is not limited to this and can be determined to various values.

[0054] According to another embodiment, the error value (ER N ) is the error standard value (TH N If the difference is less than _ER, the control unit 15 corrects the temperature values ​​(T) corresponding to each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population. In other words, the control unit 15 can correct the temperature data corresponding to each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population.

[0055] In another embodiment, the control unit 15 may calculate the temperature values ​​(T) corresponding to the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) by calculating the moving average value (MA N ), the temperature value (T) can be corrected by adding a predetermined correction value (β) to the temperature value (T). N ), the temperature value (T) can be corrected by subtracting a correction value (β) from the temperature value (T). Hereinafter, the correction value (β) is assumed to be 2, but it is not limited to this and can be determined to various values.

[0056] Referring to the above equation (2), the error value (ER N ) 0.22326 is the reference value (TH NThe control unit 15 calculates ±correction values ​​(β=2) for each of the plurality of temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) corresponding to the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population, and can correct the plurality of temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) belonging to the sample population.

[0057] According to the formula (1), the moving average value (MA N ) is 29.38°C. Specifically, the temperature value at the N-5th diagnosis point (T N-5 )29.4℃ is the moving average (MA N ) 29.38°C or higher, the control unit 15 determines that the temperature value (T N-5 , 29.4℃) and add a correction value (β=2) to obtain the processed temperature value at the N-5th diagnosis point (T N-5 , 29.4 + 2 = 31.4°C). N-4 )29.3℃ is the moving average (MA N ) 29.38°C, the control unit 15 determines that the temperature value (T N-4 , 29.3℃) is subtracted by a correction value (β=2) to obtain the processed temperature value at the N-4th diagnosis point (T N-1 , 29.3-2=27.3°C). If the temperature values ​​(29.4°C, 29.3°C, 29.5°C) at the N-3 diagnostic time point, the N-2 diagnostic time point, and the N-1 diagnostic time point (N-3, N-2, N-1) are corrected in a similar manner, the corrected temperature values ​​(T') for the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) may be 31.4°C, 27.3°C, 31.4°C, 27.3°C, 31.5°C.

[0058] When the temperature values ​​at each of the plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1) are corrected, the control unit 15 calculates a moving average value (MA) based on the corrected temperature values ​​(T') 31.4°C, 27.3°C, 31.4°C, 27.3°C, and 31.5°C at each of the plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1).N '), mean standard deviation (SD N _ave'), and error value (ER N ') can be calculated again based on the formulas (1) and (2), etc.

[0059] Next, the control unit 15 calculates the moving average value (MA N ) to the error value (ER N ) is added to the overheat reference value (Th N ) can be calculated. Th N =MA N +ER N (3)

[0060] For example, when the temperature values ​​(T) at each of the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) are corrected, the control unit 15 calculates a moving average value (MA) calculated based on the corrected temperature values ​​(T') at each of the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1). N ') and error value (ER N ') based on the overheating reference value (Th N For example, the overheat reference value (Th) calculated based on the corrected temperature values ​​(T') at each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) can be calculated. N ) is assumed to be 32.5°C.

[0061] Next, the control unit 15 calculates the temperature (T N ) value and the overheating reference value (Th N ) to diagnose whether an overheating event has occurred for the object.

[0062] For example, referring to Table 1, the temperature (T N Let us assume that the temperature (T N , 30℃) value corresponds to the overheat reference value (Th N, 32.5°C), the control unit 15 can diagnose that an overheating event has not occurred. In other words, the control unit 15 can diagnose that the temperature of the object is in a normal state.

[0063] FIG. 2 is a block diagram illustrating a battery system according to another embodiment.

[0064] Referring to FIG. 2, the battery system 2 includes a battery 10, a relay 20, and a battery management system (hereinafter referred to as BMS) 30.

[0065] Battery 10 may include multiple battery cells connected in series and / or parallel. While Figure 2 shows three battery cells connected in parallel, battery 10 is not limited to this configuration and may include various numbers of battery cells connected in series and / or parallel. In some embodiments, the battery cells may be rechargeable secondary batteries.

[0066] For example, the battery 10 may have a predetermined number of battery cells connected in parallel to form a battery bank, or a predetermined number of battery banks connected in series to form a battery pack, thereby supplying a desired power to an external device. As another example, the battery 10 may have a predetermined number of battery cells connected in parallel to form a battery bank, or a predetermined number of battery banks connected in parallel to form a battery pack, thereby supplying a desired power to an external device. However, the battery 10 is not limited to such connections, and may include a plurality of battery banks, each including a plurality of battery cells connected in series and / or parallel, and the plurality of battery banks may also be connected in series and / or parallel.

[0067] 2, a battery 10 is connected between two output terminals OUT1 and OUT2 of a battery system 2. A relay 20 is connected between the positive terminal of the battery system 2 and the first output terminal OUT1. The configurations and the connections between the configurations shown in FIG. 2 are merely examples, and the present invention is not limited thereto.

[0068] The relay 20 controls the electrical connection between the battery system 2 and the external device. When the relay 20 is turned on, the battery system 2 and the external device are electrically connected to each other and charging or discharging is performed. When the relay 20 is turned off, the battery system 2 and the external device are electrically isolated from each other. In this case, the external device may be a charger in a charging cycle that supplies power to the battery 10 to charge it, or a load in a discharging cycle that the battery 10 discharges power to the external device.

[0069] The BMS 30 includes a measurement unit 31, a storage unit 33, and a control unit 35. The overheat diagnostic device 1 shown in FIG. 1 can correspond to the BMS 30 shown in FIG. 2. Specifically, the functions performed by the measurement unit 11, storage unit 13, and control unit 15 of the overheat diagnostic device 1 can correspond to the functions performed by the measurement unit 31, storage unit 33, and control unit 35 of the BMS 30, respectively. For example, the overheat diagnostic device 1 may be configured separately from the battery system 2. As another example, as shown in FIG. 2, in the battery system 2, the BMS 30 can perform the functions of the overheat diagnostic device 1.

[0070] Hereinafter, the description of the functions of the measurement unit 31, storage unit 33, and control unit 35 of the BMS 30 will be substituted for the description of the functions of the measurement unit 11, storage unit 13, and control unit 15 of the overheat diagnostic device 1.

[0071] FIG. 3 is a flowchart illustrating an overheating diagnosis method according to an embodiment, FIG. 4 is a flowchart illustrating in detail the overheating reference value calculation step S300 of FIG. 3, and FIG. 5 is a flowchart illustrating in detail the temperature value correction step S370 of FIG. 4.

[0072] 1 to 5, an overheat diagnostic method, an overheat diagnostic device 1 that provides the method, and a battery system 2 will be described below. While the following description will be made in terms of the measurement unit 31, storage unit 33, and control unit 35 of the BMS 30, the same can be applied to the measurement unit 11, storage unit 13, and control unit 15 of the overheat diagnostic device 1. Furthermore, while the description will be made in terms of a battery 10, the present invention is not limited to this and can be applied in the same way to various objects that require temperature measurement.

[0073] First, the control unit 35 receives temperature data including information about the measured temperature of the battery 10 from the measurement unit 31 at a predetermined diagnostic time point when diagnosing overheating of the battery 10 (S100).

[0074] When a diagnosis time point according to a preset condition arrives, the measurement unit 31 can measure the temperature of the battery 10 and transmit the measurement result to the control unit 35. For example, the measurement unit 31 can include a temperature sensor to measure the temperature of the battery 10 at each diagnosis time point and transmit the measurement result to the control unit 35. As another example, the measurement unit 31 can receive a temperature value that is a result of the temperature sensor measuring the temperature of the battery 10 at a predetermined time interval or in real time, extract temperature data corresponding to the predetermined diagnosis time point, and transmit the temperature data to the control unit 35.

[0075] Next, the control unit 35 extracts a plurality of previous diagnostic time points corresponding to the number of samples (SN) based on the current diagnostic time point (N) to determine a sample group (S200).

[0076] Referring to Table 1, when the control unit 35 counts the diagnosis time points from the current diagnosis time point (N) toward the previous diagnosis time point, it can extract the N-5th diagnosis time point, the N-4th diagnosis time point, the N-3rd diagnosis time point, the N-2th diagnosis time point, and the N-1st diagnosis time point, which correspond to five sample numbers (SN), to determine the sample group.

[0077] The control unit 35 extracts a plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) to determine a sample group, and calculates the temperature values ​​(T N-5 , T N-4 , T N-3 , T N-2 , T N-1 ) based on the overheating reference value (Th N ) can be calculated using the following method. N ) can prevent the problem of misdiagnosing a temperature rise due to battery aging as an overheating event. Also, it can solve the problem of misdiagnosing a temporary temperature rise due to various causes as an overheating event.

[0078] Next, the control unit 35 calculates a plurality of temperature values ​​(T N-5 , T N-4 , T N-3 , T N-2 , T N-1 ) based on the Nth diagnostic point in time, the overheat reference value (Th N ) is calculated (S300).

[0079] Referring to FIG. 4, in step S300, the control unit 35 averages a plurality of temperature values ​​corresponding to a plurality of diagnostic time points belonging to the sample group to obtain a moving average value (MA) corresponding to the Nth diagnostic time point. N ) is calculated (S310).

[0080] Specifically, referring to Table 1, the control unit 35 averages a plurality of temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) corresponding to a plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population (29.4°C + 29.3°C + 29.4°C + 29.3°C + 29.5°C / 5 = 29.38°C) to obtain a moving average value (MA) corresponding to the Nth diagnostic time point. N , 29.38℃) can be calculated.

[0081] In step S300, the control unit 35 averages a plurality of standard deviations corresponding to a plurality of diagnostic time points belonging to the sample population to obtain a mean standard deviation (SD N _ave) and calculate the standard deviation mean (SD N Based on the _ave, the error value (ER N ) is calculated (S330).

[0082] Specifically, referring to Table 3, the control unit 35 calculates a plurality of standard deviations (SD) corresponding to a plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population. N-5 , S.D. N-4 , S.D. N-3 , S.D. N-2 , S.D. N-1 ) based on the standard deviation mean (SD N _ave, 0.07442) can be calculated.

[0083] The control unit 15 calculates the standard deviation average value (SD N _ave) is multiplied by a preset factor (α) to obtain the error value (ER N ) can be calculated. In this case, the multiple (α) can be determined to various values ​​through experiments. Hereinafter, the multiple (α) is assumed to be a natural number 3 (α=3). For example, referring to Table 3 and the above equation (2), the control unit 15 calculates the standard deviation average (SD N _ave=0.07442) is multiplied by a factor (α=3) to obtain the error value (ER N )0.22326 can be calculated.

[0084] In step S300, the control unit 35 calculates the error value (ER N ) and a predetermined error criterion (TH N _ER) (S350).

[0085] Error value (ER N ) is a value that reflects the error that can occur in various situations, such as temperature measurement. N ) is very small, the moving average (MA N) and the overheating reference value (Th) may be very close. In other words, even if no overheating event actually occurs, the temperature (T N ) is the overheating reference value (Th N ) may result in a false diagnosis of an overheating event. In other words, if the error value (ER) on which the overheating reference value (Th) is calculated is smaller than the generally expected value, there is a high possibility of a false diagnosis.

[0086] In step S300, as a result of the comparison, an error value (ER N ) is the error standard value (TH N If the difference is smaller than the value N_ER, the control unit 15 corrects the temperature values ​​(T) corresponding to the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population (S370).

[0087] For example, the error criterion (TH N _ER) is the moving average (MA N ) (29.38°C x 0.01 = 0.2938), but is not limited to this and can be determined as various values.

[0088] Referring to FIG. 4, in step S370, the control unit 15 extracts a plurality of temperature values ​​corresponding to a plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population (S371).

[0089] At step S370, the control unit 15 calculates a moving average value (MA) of each of the plurality of temperature values. N ) is compared (S372).

[0090] For example, for each of the plurality of temperature values, the control unit 15 calculates the moving average value (MA N ) or more.

[0091] In step S370, as a result of the comparison, the temperature value is determined to be a moving average value (MA N) (S372, YES), the control unit 15 corrects the temperature value by adding a predetermined correction value (β) to the temperature value (S373).

[0092] In step S370, as a result of the comparison, the temperature value is determined to be a moving average value (MA N If the temperature is smaller than the reference temperature (S372, NO), the control unit 15 subtracts the correction value (β) from the temperature value to correct the temperature value (S374).

[0093] For example, referring to Table 1, the moving average (MA) of multiple diagnosis points (N-5, N-4, N-3, N-2, N-1) belonging to the sample group is N The temperature value (T) can be corrected by adding a correction value (β=2) to the temperature values ​​(29.4°C, 29.4°C, 29.5°C) at the N-5th, N-3rd, and N-1st diagnostic time points corresponding to the temperature values ​​(29.4°C, 29.4°C, 29.5°C) or higher. In addition, the moving average (MA) of multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population can be calculated. N The temperature value (T) can be corrected by subtracting the correction value (β=2) from the temperature values ​​(29.3°C, 29.3°C) at the N-4th and N-2nd diagnostic time points, which correspond to temperatures less than 29.3°C (29.3°C, 29.3°C). The temperature values ​​of 29.4°C, 29.3°C, 29.4°C, 29.3°C, and 29.5°C at the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) can be corrected to 31.4°C, 27.3°C, 31.4°C, 27.3°C, and 31.5°C.

[0094] 4 and 5, the control unit 15 performs steps S310 and S330 again according to the corrected temperature values ​​(T') of 31.4°C, 27.3°C, 31.4°C, 27.3°C, and 31.5°C at the respective diagnosis points (N-5, N-4, N-3, N-2, and N-1) to calculate the corrected moving average value (MA N ') and the corrected error value (ER N Then, the corrected error value (ER ') can be calculated again as a result of the judgment in step S350. N ') is the corrected error standard value (TH NIf the error is greater than the reference error (TH_ER') (YES in S350), the process proceeds to step S390. That is, steps S370, S310, and S330 are repeated until the result of the determination in step S350 is YES. At this time, the corrected error reference value (TH N _ER') is the corrected moving average (MA N It can be calculated as a value corresponding to 1% of

[0095] In step S370, the control unit 15 determines whether all of the temperature values ​​corresponding to the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population have been corrected (S375).

[0096] If it is determined in step S370 that there is an uncorrected temperature value among the plurality of temperature values ​​(S375, NO), the control unit 15 repeats the process from step S372.

[0097] If it is determined in step S370 that all of the temperature values ​​belonging to the sample group have been corrected (YES in step S375), the control unit 15 outputs the corrected temperature values ​​(T N-5 ', T N-4 ', T N-3 ', T N-2 ', T N-1 ') is stored in the storage unit 33, and the correction can be completed (S376).

[0098] According to an embodiment, even if the temperature value is corrected in step S370 at the Nth diagnosis time point, the plurality of temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) measured at each of the plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1) and pre-stored in the storage unit 33 may not be corrected. In other words, even if the temperature value is corrected in step S370 at the Nth diagnosis time point, the corrected moving average value (MA N ') and the corrected error value (ER N Based on the corrected superheat reference value (Th N) can only be calculated.

[0099] According to another embodiment, if the temperature value is corrected in step S370 at the Nth diagnostic time point, the plurality of temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) measured at each of the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) and pre-stored in the storage unit 33 can be changed to the corrected plurality of temperature values ​​(31.4°C, 27.3°C, 31.4°C, 27.3°C, 31.5°C). Therefore, at the subsequent N+1th diagnostic time point, N+2th diagnostic time point, etc., the moving average (MA) N+1 , M.A. N+2 ) and the corrected error value (ER N+1 +ER N+2 When calculating the temperature, it can be calculated based on multiple temperature values ​​corrected at the Nth diagnostic point in time.

[0100] Referring again to FIG. 4, in step S300, the control unit 15 calculates the moving average value (MA N or MA N ') to the error value (ER N or ER N ') is added to the overheat reference value (Th N or Th N ') is calculated (S390).

[0101] For example, when the temperature values ​​(T) at each of the plurality of diagnostic time points (N-5, N-4, N-3, N-2, N-1) are corrected, the control unit 15 calculates a corrected moving average value (MA) calculated based on the temperature values ​​(T') at each of the plurality of corrected diagnostic time points (N-5, N-4, N-3, N-2, N-1). N ') and the corrected error value (ER N ') is added to the corrected superheat reference value (Th N For example, the corrected overheat reference value (Th ') calculated based on the temperature values ​​(T') at each of the corrected multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) can be calculated. N ') is assumed to be 32.5℃.

[0102] Next, referring back to FIG. 3, the control unit 35 determines the temperature (T N ) value and overheating reference value (Th N ) to diagnose whether an overheating event has occurred in the battery 10 (S400).

[0103] In step S400, the control unit 35 determines the temperature (T N ) value is the overheating reference value (Th N ) (S410).

[0104] In step S400, as a result of the determination, the temperature (T N ) value is the overheating reference value (Th N ) (S410, Yes), the control unit 35 diagnoses that an overheating event has occurred in the battery 10 (S420).

[0105] In step S400, as a result of the determination, the temperature (T N ) value is the overheating reference value (Th N ) or less (S400, NO), the control unit 35 diagnoses the temperature of the battery 10 as being normal (S430).

[0106] For example, referring to Table 1, the temperature (T N Let us assume that the temperature (T N , 30℃) value corresponds to the overheat reference value (Th N , 32.5°C), the control unit 35 can diagnose that an overheating event has not occurred. In other words, the control unit 35 can diagnose that the temperature of the object is in a normal state.

[0107] FIG. 6 is an example diagram showing the temperature change of a non-defective battery in the charging mode, and FIG. 7 is an example diagram showing the temperature change of a defective battery in the charging mode.

[0108] 6 and 7, the X-axis represents time (sec) and the Y-axis represents temperature (° C.).

[0109] Referring to FIG. 6, there is shown an example of temperature change over time when a non-defective battery is charged at various external temperatures.

[0110] For example, when the ambient temperature is 25° C., in a charging mode in which the battery 10 is charged by power from an external device, the temperature change of the battery 10 over time is shown in the first graph T A As another example, when the battery 10 is being charged at an ambient temperature of 30° C., the temperature change of the battery 10 over time is shown in the second graph T B Similarly, the temperature change of the battery 10 when the atmospheric temperature is 35° C. and when the atmospheric temperature is 40° C. can be represented by the third graph T C and the fourth graph T D It can respond to.

[0111] That is, for a battery 10 that is in a normal state according to a predetermined standard or a new battery 10 that has not been used, the starting temperature value may be different as the external temperature changes, but the temperature change over time (i.e., the slope) may be constant, as shown in FIG. 6.

[0112] Referring to FIG. 7, this is an example graph derived from an experiment showing temperature change over time when a defective battery is charged at a predetermined external temperature.

[0113] In this case, the solid line FL represents the actually measured battery temperature, and the dotted line DL shown adjacent to the solid line FL represents the reference line. The reference line may be formed by connecting overheating reference values ​​calculated at each diagnosis point according to an embodiment. Referring to Figures 6 and 7, the temperature change of a non-defective battery forms a straight line graph as in Figure 6, while the temperature change of a defective battery may form a curved line graph as in Figure 7.

[0114] Conventionally, if the temperature of the battery 10 exceeds a fixed overheating reference value (e.g., 60°C), the occurrence of an overheating event is diagnosed at that time. Referring to Figure 7, conventionally, the occurrence of an overheating event of the battery 10 can be first diagnosed at the second time point AD2.

[0115] However, according to the overheating diagnosis method of the embodiment, it is possible to diagnose the occurrence of an overheating event in advance before the temperature of the battery 10 exceeds a fixed overheating reference value (e.g., 60°C). As a result of the experiment, the occurrence of an overheating event in the battery 10 was first diagnosed at a first time point AD1. Specifically, as a result of the diagnosis, an overheating event was continuously diagnosed at each diagnosis time point from the first time point AD1, when the solid line FL crosses the dotted line DL, to the second time point AD2.

[0116] 7, the experimental result shows that there is a time difference of about 1000 seconds (about 16 minutes) between the first time point AD1 and the second time point AD2. The overheating diagnosis method according to the embodiment has an advantage that it is possible to know in advance the occurrence of an overheating event in the battery 10 and take measures against it.

[0117] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. a measuring unit for measuring a temperature of an object; a storage unit for storing the temperature value measured by the measurement unit; and a control unit that, for each diagnostic time point at which overheating of the object is diagnosed, extracts a plurality of previous diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average which is the average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation average which is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and, if an error value calculated by multiplying the standard deviation average by a predetermined multiple is equal to or greater than a predetermined error reference value, calculates an overheating reference value by adding the error value to the moving average, and compares the temperature values ​​measured at each diagnostic time point with the overheating reference value calculated for each diagnostic time point to diagnose the occurrence of an overheating event for the object.

2. The overheating diagnostic device of claim 1, wherein the control unit corrects the plurality of temperature values ​​according to the results of comparing each of the plurality of temperature values ​​corresponding to the plurality of diagnostic time points with the moving average value if the error value is less than the error reference value, and calculates the overheating reference value based on the corrected plurality of temperature values.

3. The overheating diagnostic device of claim 2, wherein the control unit, for each of the plurality of temperature values, if the temperature value is equal to or greater than the moving average value, adds a predetermined correction value to the temperature value, and if the temperature value is less than the moving average value, subtracts the correction value from the temperature value to correct the temperature value.

4. The overheat diagnostic device according to claim 1 , wherein the control unit diagnoses that an overheat event has occurred in the object if the measured temperature value exceeds the overheat reference value.

5. a battery including a plurality of battery cells; a measurement unit for measuring the temperature of the battery; a storage unit for storing the temperature value measured by the measurement unit; a control unit that, for each diagnostic time point at which overheating of the battery is diagnosed, extracts a plurality of previous diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average which is an average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation average which is an average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and, if an error value calculated by multiplying the standard deviation average by a predetermined multiple is equal to or greater than a predetermined error reference value, calculates an overheating reference value by adding the error value to the moving average, and compares the temperature value measured at each diagnostic time point with the overheating reference value calculated for each diagnostic time point to diagnose the occurrence of an overheating event in the battery.

6. 6. The battery system according to claim 5, wherein, if the error value is less than the error reference value, the control unit corrects the plurality of temperature values ​​according to a result of comparing each of the plurality of temperature values ​​corresponding to the plurality of diagnostic time points with the moving average value, and calculates the overheating reference value based on the corrected plurality of temperature values.

7. 7. The battery system according to claim 6, wherein the control unit corrects each of the plurality of temperature values ​​by adding a predetermined correction value to the temperature value if the temperature value is equal to or greater than the moving average value, and by subtracting the predetermined correction value from the temperature value if the temperature value is less than the moving average value.

8. The battery system according to claim 5 , wherein the control unit diagnoses that an overheating event has occurred in the battery if the measured temperature value exceeds the overheating reference value.

9. a temperature data collection step of receiving a temperature value, which is a temperature measurement value of the battery, from a measurement unit at a predetermined time point when diagnosing overheating of the battery including a plurality of battery cells; A sample group determination step of extracting a plurality of previous diagnosis time points corresponding to the number of samples based on the diagnosis time point; an overheating reference value calculation step including a step of calculating a moving average value which is an average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points; a step of calculating a standard deviation average value which is an average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points and multiplying the standard deviation average value by a predetermined multiple to calculate an error value; and a step of calculating an overheating reference value by adding the error value to the moving average value if the calculated error value is equal to or greater than a predetermined error reference value; an overheat diagnosis step of comparing the temperature value with the overheat reference value to diagnose an occurrence of an overheat event in the battery.

10. the calculating of the overheat reference value further includes a temperature value correcting step of correcting the plurality of temperature values ​​according to a result of comparing each of the plurality of temperature values ​​corresponding to the plurality of diagnostic time points with the moving average value if the error value is less than the error reference value; The overheat diagnostic method according to claim 9 , wherein the step of calculating the overheat reference value calculates the overheat reference value based on the corrected plurality of temperature values.

11. The temperature value correcting step includes: extracting a plurality of temperature values ​​corresponding to the plurality of diagnostic time points; comparing each of the plurality of temperature values ​​with the moving average value; a first correction step of correcting the temperature value by adding a predetermined correction value to the temperature value if the temperature value is equal to or greater than the moving average value as a result of the comparison; The overheat diagnostic method according to claim 10, further comprising: a second correction step of correcting the temperature value by subtracting a predetermined correction value from the temperature value if the temperature value is less than the moving average value.

12. The overheat diagnosis step includes: comparing the measured temperature value with the overheat reference value; a first diagnosis step of diagnosing that an overheating event has occurred in the battery if the measured temperature value exceeds the overheating reference value as a result of the comparison; 10. The overheat diagnostic method of claim 9, further comprising: a second diagnostic step of diagnosing the battery as being in a normal state and not experiencing an overheat event if the measured temperature value is equal to or less than the overheat reference value as a result of the comparison.

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