Overheating diagnostic method, overheating diagnostic device providing the method, and battery system

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 of related applications] This application claims priority rights under Korean Patent Application No. 10-2022-0185631 dated December 27, 2022, and Korean Patent Application No. 10-2023-0185646 dated December 19, 2023, and all content disclosed in the documents of said Korean Patent Applications is incorporated herein by reference.

[0002] The present invention relates to a method for diagnosing overheating of an object (e.g., a battery), an overheating diagnostic device providing such a method, and a battery system. [Background technology]

[0003] Recently, with the rapid increase in demand for portable electronic products such as laptops, video cameras, and mobile phones, and with the full-scale development of electric vehicles, energy storage batteries, robots, and artificial satellites, research into high-performance batteries capable of repeated charging and discharging is progressing actively.

[0004] Currently available commercially include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention because they exhibit almost no memory effect compared to nickel-based batteries, allow for flexible charging and discharging, have a very low self-discharge rate, and have a high energy density.

[0005] On the other hand, battery temperature is a factor that significantly affects battery performance. Generally, batteries can operate efficiently when their temperature is distributed within an appropriate range. For example, if the battery temperature is excessively high, the safety of the battery's negative electrode crystal lattice may decrease, leading to a decline in battery performance or even accidents such as explosions. Therefore, it is necessary to accurately monitor the battery temperature.

[0006] Traditionally, battery overheating was diagnosed by comparing the measured battery temperature with a preset reference value. However, this conventional method has a problem: the time interval between the diagnosis of an overheating event and the actual occurrence of battery explosion or other damage is excessively short, making it difficult to take appropriate measures. Furthermore, this conventional method has the problem of misdiagnosing temperature increases due to battery aging as an overheating event. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention relates to an overheating diagnostic method that can accurately diagnose abnormal heat generation behavior (hereinafter referred to as overheating) in an object, an overheating diagnostic device that provides this method, and a battery system. [Means for solving the problem]

[0008] An overheating diagnostic device according to one feature of the present invention includes a measuring unit for measuring the temperature of an object, a storage unit for storing the temperature values ​​measured by the measuring unit, and a control unit that, for each diagnostic time point in which overheating of the object 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 value which is the average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation mean value which is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and if the error value calculated by multiplying the standard deviation mean value by a predetermined multiple is greater than or equal to a predetermined error standard value, calculates an overheating standard value by adding the error value to the moving average value, and diagnoses the occurrence of an overheating event for the object by comparing the temperature values ​​measured for each diagnostic time point with the overheating standard value calculated for each diagnostic time point.

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

[0010] The control unit can correct 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 correction value from the temperature value if the temperature value is less than the moving average value.

[0011] The control unit can diagnose that an overheating event has occurred in the object if the measured temperature value exceeds the overheating threshold value.

[0012] A battery system according to other features of the present invention includes a battery containing a plurality of battery cells, a measuring unit for measuring the temperature of the battery, a storage unit for storing the temperature values ​​measured by the measuring unit, and a control unit that, for each diagnostic time point in 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 value which is the average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation mean which is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and if the error value calculated by multiplying the standard deviation mean by a predetermined multiple is greater than or equal to a predetermined error standard value, calculates an overheating standard value by adding the error value to the moving average value, and diagnoses the occurrence of an overheating event in the battery by comparing the temperature values ​​measured at each diagnostic time point with the overheating standard value calculated at each diagnostic time point.

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

[0014] The control unit can correct 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 a predetermined correction value from the temperature value if the temperature value is less than the moving average value.

[0015] The control unit can diagnose that an overheating event has occurred in the battery if the measured temperature value exceeds the overheating threshold value.

[0016] A further feature of the present invention provides an overheating diagnostic method that includes: a temperature data acquisition step of receiving a temperature value, which is a temperature measurement of the battery, from a measurement unit at a predetermined diagnostic time for diagnosing overheating of a battery including a plurality of battery cells; a sample group determination step of extracting a plurality of diagnostic time points corresponding to the number of samples based on the diagnostic time point; a step of calculating a moving average value, which is the average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points; a step of calculating a standard deviation mean, which is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and calculating an error value by multiplying the standard deviation mean by a predetermined multiple; a step of calculating an overheating reference value by adding the error value to the moving average value if the calculated error value is greater than or equal to a predetermined error reference value; and an overheating diagnostic step of comparing the temperature value with the overheating reference value to diagnose the occurrence of an overheating event in the battery.

[0017] The overheating reference value calculation step further includes a temperature value correction step in which, if the error value is less than the error reference value, the plurality of temperature values ​​are corrected according to the result of comparing each of the plurality of temperature values ​​corresponding to the plurality of diagnostic time points with the moving average value, and the overheating reference value calculation step can calculate the overheating reference value based on the corrected plurality of temperature values.

[0018] The temperature value correction step may include: extracting a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points; comparing each of the plurality of temperature values ​​with the moving average value; a first correction step in which, if the temperature value is equal to or greater than the moving average value as a result of the comparison, a predetermined correction value is added to the temperature value to correct it; and a second correction step in which, if the temperature value is less than the moving average value, a predetermined correction value is subtracted from the temperature value to correct it.

[0019] The overheating diagnostic step may include a step of comparing the measured temperature value with the overheating reference value; a first diagnostic step of diagnosing that an overheating event has occurred in the battery if, as a result of the comparison, the measured temperature value exceeds the overheating reference value; and a second diagnostic step of diagnosing that, as a result of the comparison, the measured temperature value is less than or equal to the overheating reference value, the battery is in a normal state and no overheating event has occurred. [Effects of the Invention]

[0020] Unlike conventional methods that use fixed reference values ​​for diagnosis, this invention calculates an overheat reference value that reflects the temperature trend for the object at each overheat diagnosis point, and performs an overheat diagnosis by comparing the calculated overheat reference value with the measured temperature, thereby enabling a highly accurate determination of whether or not an overheat event has occurred.

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

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

[0023] [Figure 1] This is a block diagram illustrating an overheating diagnostic device according to one embodiment. [Figure 2] This is a block diagram illustrating a battery system according to another embodiment. [Figure 3] This is a flowchart illustrating the overheating diagnosis method according to the embodiment. [Figure 4] Figure 3 is a flowchart that provides a detailed explanation of the overheating standard value calculation step S300. [Figure 5] This is a flowchart that explains in detail the temperature value correction step S370 in Figure 4. [Figure 6] This is an illustrative diagram showing the temperature change of a defect-free battery in charging mode. [Figure 7] This is an illustrative diagram showing the temperature change of a defective battery in charging mode. [Modes for carrying out the invention]

[0024] The embodiments disclosed herein will be described in detail below with reference to the attached drawings, with identical or similar components numbered identically or similarly, and redundant descriptions thereof will be omitted. The suffixes “module” and / or “part” used for components in the following description are added or mixed solely for the sake of ease of specification preparation and do not have any distinguishing meaning or role in themselves. Furthermore, in describing the embodiments disclosed herein, if it is determined that a specific description of such known technology may obscure the gist of the embodiments disclosed herein, such detailed description will be omitted. Moreover, it should be understood that the attached drawings are merely for the purpose of facilitating the understanding of the embodiments disclosed herein, and that the technical ideas disclosed herein are not limited by the attached drawings, and include all modifications, equivalents or substitutes that fall within the concept and technical scope of the present invention.

[0025] Terms including ordinal numbers, such as "first," "second," etc., may be used to describe a variety of components, but the components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0026] When it is mentioned that one component is "linked" or "connected" to another component, it should be understood that this may mean that the other component is directly linked or connected to it, but that other components may also be present in between. Conversely, when it is mentioned that one component is "directly linked" or "directly connected" to another component, it should be understood that there are no other components present in between.

[0027] In this application, terms such as “includes” or “having” are intended to specify the presence of features, figures, stages, actions, components, parts, or combinations thereof as described in the specification, and should be understood not to preemptively exclude the possibility of the presence or addition of one or more other features, figures, stages, actions, components, parts, or combinations thereof.

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

[0029] Referring to Figure 1, the overheating 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 point in time when overheating of the object is diagnosed (hereinafter referred to as the diagnosis point) and transmit the measurement results to the control unit 15. For example, the measurement unit 11 may include a temperature sensor for measuring the temperature of the object. In this case, the object may include, but is not limited to, a battery, and may include a variety of devices that need to be predicted in advance before an overheating event occurs.

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

[0032] The control unit 15 calculates a moving average value (MA) and an overheating threshold value (Th) that is greater than a predetermined value than the moving average value when a diagnostic time based on pre-set conditions arrives. For example, if the object is a battery, the diagnostic time may be when the battery charging begins or when the battery discharging ends. However, it is not limited to these, and the diagnostic time can be set in a variety of ways.

[0033] First, when the control unit 15 counts diagnostic time points in the direction of previous diagnostic time points based on the current diagnostic time point (N), it can extract multiple diagnostic time points included in a preset number of samples (SN) to determine the sample population. At this time, the number of samples (SN) is the number of multiple diagnostic time points included in the sample population, and can be determined to an optimal number based on experiments or other factors.

[0034] The sample population may be a subgroup of the population at multiple past diagnostic points, and may be a group used to calculate the moving mean (MA) and standard deviation mean (SD_ave), as 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), average standard deviation (SD_ave), error value (ER), and overheating threshold value (Th) of an object corresponding to multiple diagnostic time points. Below, the overheating threshold value (Th) required for overheating diagnosis at the Nth diagnostic time point is shown. N The method for calculating the sample size (SN) will be explained in detail. We will also assume the sample size (SN) is 5. However, it is not limited to this, and the sample size (SN) can be determined to a variety of positive integers.

[0037] For reference, in Table 1, at the initial diagnostic time (1), there are no prior diagnostic time points that constitute the sample population, so it may be difficult to directly calculate the moving mean (MA), standard deviation (SD), mean standard deviation (SD_ave), and overheating threshold (Th) (therefore, the corresponding values ​​in Table 1 are shown as blank). In addition, at predetermined diagnostic time points adjacent to the initial diagnostic time point (1) (e.g., 2, 3, 4, 5), there are insufficient numbers of prior diagnostic time points that constitute the sample population, making it difficult to calculate the moving mean (MA), standard deviation (SD), mean standard deviation (SD_ave), and overheating threshold (Th). In this case, the designer can provide values ​​that are calculated on average by experiment as the moving mean (MA), standard deviation (SD), mean standard deviation (SD_ave), and overheating threshold (Th) for the initial diagnostic time point and adjacent diagnostic time points (e.g., 1, 2, 3, 4, 5).

[0038] When the control unit 15 counts the diagnostic times in the forward direction with respect to the current diagnostic time, the Nth diagnostic time (N), it can extract the N-1st, N-2nd, N-3rd, N-4th, and N-5th diagnostic times, which correspond to 5 samples in the sample size (SN), and determine the sample population.

[0039] The control unit 15 extracts multiple diagnostic time points (N-1, N-2, N-3, N-4, N-5) to determine a sample population, and based on the temperature values ​​measured at each of the multiple diagnostic time points (N-1, N-2, N-3, N-4, N-5) belonging to the sample population, determines the overheating reference value (Th) used for overheating diagnosis. N It is possible to calculate ).

[0040] For example, if the object is a battery, prolonged use of the battery may cause its internal resistance to increase due to aging, and this increase in internal resistance may cause the temperature to gradually rise. Depending on the embodiment, the overheating threshold value (Th NWhen diagnosing overheating of the battery based on , it is possible to prevent the problem of misdiagnosing the temperature rise due to long-term use as the occurrence of an overheating event. Also, it is possible to solve the problem of misdiagnosing a temporary temperature rise as the occurrence of an overheating event.

[0041] Next, based on the temperature values (T) measured at each of a plurality of diagnosis time points (N-1, N-2, N-3, N-4, N-5) belonging to the sample population, the control unit 15 determines the overheating reference value (Th N ) corresponding to the Nth diagnosis time point.

[0042] According to one embodiment, the control unit 15 compares the temperature value (T N ) measured at the Nth diagnosis time point with the overheating reference value (Th N ) calculated at the Nth diagnosis time point to diagnose whether the object is overheated. For example, referring to Table 1, the moving average value (MA N ) and the standard deviation average value (SD N _ave) are values necessary for calculating the overheating reference value (Th N ). The standard deviation (SD N ) is not a value necessary for diagnosing the overheating state at the Nth diagnosis time point, but since it is necessary for determining an overheating event at a later diagnosis time point (N+1, N+2,...), it may be calculated at the Nth diagnosis time point and stored in the storage unit 13.

[0043] Hereinafter, referring to Table 1, the moving average value (MA N ), standard deviation (SD N ), standard deviation average value (SD N _ave), error value (ER N ) and overheating reference value (Th N ) calculated by the control unit 15 at the Nth diagnosis time point will be described.

[0044] The control unit 15 averages the plurality of temperature values (29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) corresponding to each of the plurality of diagnosis 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 the moving average value (MAN It is possible to calculate the moving average value (MA) at the Nth diagnostic time point. 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 above and Table 2 below, the control unit 15 calculates the temperature value (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, and the moving average value (MA) corresponding to the Nth diagnostic time point (N). N Based on this, the standard deviation (SD) corresponding to the Nth diagnostic time point is calculated. N It is possible to calculate ).

[0046] [Table 2]

[0047] As explained earlier, the standard deviation (SD) corresponding to the Nth diagnostic time point N The standard deviation (SD) corresponding to the Nth diagnostic time point is not a value needed when diagnosing the overheating state at the Nth diagnostic time point, but it is needed when diagnosing whether or not an overheating event has occurred in the object at subsequent diagnostic time points (N+1, N+2, ...). Therefore, the standard deviation (SD) corresponding to the Nth diagnostic time point is not needed. N ) may be calculated at the Nth diagnostic stage and stored in the storage unit 13.

[0048] [Table 3]

[0049] The control unit 15, referring to Tables 1 and 3, determines multiple standard deviations (SD) corresponding to multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population. N-5 SD N-4 SD N-3 SD N-2 SDN-1 Based on this, the mean standard deviation (SD) corresponding to the Nth diagnostic time point. N _ave (0.07442) can be calculated.

[0050] The control unit 15 calculates the moving average value (MA). N Overheating standard value (Th N The control unit 15 can calculate the mean standard deviation (SD) using the following formula (2). First, the control unit 15 calculates the mean standard deviation (SD) using the following formula (2). N Multiply the _ave) by a predetermined multiple (α) to get 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 a variety of values ​​through experimentation. Hereafter, we will assume that the multiple (α) is a natural number 3 (α=3). ER N =SD N _ave×α (2)

[0051] For example, referring to Table 3 and formula (2), the control unit 15 calculates the mean standard deviation (SD N Multiply _ave=0.07442) by a multiple (α=3) to get the error value (ER N )0.22326 can be calculated.

[0052] Error value (ER N The error value (ER) is a value that reflects the errors that can occur in various situations, such as temperature measurement. N If ) is very small, the moving average (MA) N ) and overheating standard value (Th N The interval between this and the actual temperature (T) may be very narrow. In other words, even though no overheating event has actually occurred, the temperature measured at the Nth diagnostic point may be very narrow. N The value of (Th) is the overheating standard value calculated at the Nth diagnostic stage. N An arithmetic calculation exceeding the overheating threshold (Th) can lead to a misdiagnosis of an overheating event. N If the error value (ER) used as the basis for calculation is smaller than the generally expected value, there is a high probability of misdiagnosis.

[0053] According to one embodiment, the error value (ER N ) is a predetermined error standard value (TH N If the value is above _ER, the control unit 15 will set the moving average value (MA N ) to error value (ER N Add ) to obtain the overheating threshold value (Th N ) can be calculated below. N _ER) is the moving average (MA N We assume this value corresponds to 1% of (29.38℃ × 0.01 = 0.2938), but it is not limited to this and can be determined to a variety of values.

[0054] In other embodiments, the error value (ER N ) is the error standard value (TH N If the value is less than _ER, the control unit 15 corrects the temperature value (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 other embodiments, the control unit 15 calculates the moving average (MA) of the temperature value (T) corresponding to each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1). N If the temperature value (T) is above a certain value, the temperature value (T) can be corrected by adding a predetermined correction value (β). The moving average (MA) of the temperature values ​​(T) corresponding to each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) N If the value is less than ), the temperature value (T) can be corrected by subtracting the correction value (β). Below, we assume that the correction value (β) is 2, but it is not limited to this and can be determined to various values.

[0056] Referring to formula (2) above, the error value (ER N )0.22326 is the reference value (TH N_ER) is less than 0.2938. The control unit 15 can correct the multiple temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) belonging to the sample population by calculating a ± correction value (β=2) for each of the multiple 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 above formula (1), the moving average value (MA) N The temperature is 29.38℃. Specifically, the temperature value (T) at the N-5th diagnostic time point. N-5 ) 29.4℃ is the moving average (MA) N Since the temperature is 29.38℃ or higher, the control unit 15 determines the temperature value (T) at the N-5 diagnostic time. N-5 Adding a correction value (β=2) to the temperature value (T) at the N-5th diagnostic point (29.4℃) gives the processed temperature value (T) N-5 The temperature value (T) at the N-4th diagnostic point can be calculated as follows: N-4 ) 29.3℃ is the moving average (MA N Since it is less than 29.38℃, the control unit 15 determines the temperature value (T) at the N-4 diagnostic time. N-4 Subtracting a correction value (β=2) from the temperature (T) at the N-4th diagnostic point (29.3℃) gives the processed temperature value (T) N-1 , 29.3-2=27.3℃ can be calculated. If the temperature values ​​for the N-3, N-2, and N-1 diagnostic time points (N-3, N-2, N-1) are corrected in the same way, the corrected temperature values ​​(T') for each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) may be 31.4℃, 27.3℃, 31.4℃, 27.3℃, and 31.5℃.

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

[0059] Next, the control unit 15 calculates the moving average value (MA) using the following formula (3). N ) to error value (ER N Add ) to obtain the overheating threshold value (Th N It is possible to calculate ). Th N =MA N +ER N (3)

[0060] For example, if the temperature values ​​(T) at each of the multiple 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) 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). N ') and error value (ER N Based on '), the overheating standard value (Th N ) can be calculated. For example, the overheating threshold value (Th) can be calculated based on the corrected temperature values ​​(T') for each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1). N ) is assumed to be 32.5℃.

[0061] Next, the control unit 15 determines the temperature (T) measured at the Nth diagnostic time. N ) value and the overheating standard value (Th) calculated at the Nth diagnostic point N By comparing this with the data, it is possible to diagnose whether or not an overheating event has occurred for the object.

[0062] For example, referring to Table 1, the temperature measured at the Nth diagnostic point (T N Let's assume the value is 30°C. The temperature (T) corresponding to the Nth diagnostic time point. N The value (30℃) corresponds to the overheating standard value (Th) at the Nth diagnostic point. NSince it is less than 32.5℃, the control unit 15 can diagnose that no overheating event has occurred. In other words, the control unit 15 can diagnose that the object's temperature is in a normal state.

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

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

[0065] Battery 10 may include multiple battery cells connected in series and / or parallel. Figure 2 shows three battery cells connected in parallel, but is not limited to this, and battery 10 may include any number of battery cells connected in series and / or parallel. In one embodiment, the battery cells may be rechargeable secondary batteries.

[0066] Furthermore, for example, the battery 10 can supply desired power to an external device by connecting a predetermined number of battery cells in parallel to form a battery bank, and by connecting a predetermined number of battery banks in series to form a battery pack. As another example, the battery 10 can supply desired power to an external device by connecting a predetermined number of battery cells in parallel to form a battery bank, and by connecting a predetermined number of battery banks in parallel to form a battery pack. However, it is not limited to such connections, and the battery 10 includes multiple battery banks, each containing multiple battery cells connected in series and / or in parallel, and multiple battery banks can also be connected in series and / or in parallel.

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

[0068] Relay 20 controls the electrical connection between the battery system 2 and the external device. When relay 20 is turned on, the battery system 2 and the external device are electrically connected, and charging or discharging takes place. When relay 20 is turned off, the battery system 2 and the external device are electrically isolated. At this time, the external device may be a charger in a charging cycle where power is supplied to charge the battery 10, or a load in a discharging cycle where the battery 10 discharges power to the external device.

[0069] The BMS30 includes a measurement unit 31, a storage unit 33, and a control unit 35. The overheating diagnostic device 1 shown in Figure 1 can correspond to the BMS30 shown in Figure 2. Specifically, the functions performed by the measurement unit 11, storage unit 13, and control unit 15 of the overheating diagnostic device 1 can correspond to the functions performed by the measurement unit 31, storage unit 33, and control unit 35 of the BMS30. For example, the overheating diagnostic device 1 may be configured separately from the battery system 2. As another example, as shown in Figure 2, the BMS30 can perform the functions of the overheating diagnostic device 1 within the battery system 2.

[0070] The following explanations of the functions of the measurement unit 31, storage unit 33, and control unit 35 of the BMS30 will be replaced by the explanations of the functions of the measurement unit 11, storage unit 13, and control unit 15 of the overheat diagnostic device 1.

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

[0072] The overheating diagnostic method, the overheating diagnostic device 1 providing this method, and the battery system 2 will be described below with reference to Figures 1 to 5. While the measurement unit 31, storage unit 33, and control unit 35 of the BMS 30 will be described below, the same methods are applicable to the measurement unit 11, storage unit 13, and control unit 15 of the overheating diagnostic device 1. Furthermore, while the battery 10 will be described, the method is not limited to this and can be applied equally to a variety of objects requiring temperature measurement.

[0073] First, at a predetermined diagnostic point in which the battery 10 is diagnosed as overheating, the control unit 35 receives temperature data from the measurement unit 31, which includes information regarding the measured temperature of the battery 10 (S100).

[0074] When a diagnostic time point based on pre-set conditions 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, by including a temperature sensor, the measurement unit 31 can measure the temperature of the battery 10 at each diagnostic time point and transmit the measurement result to the control unit 35. As another example, the measurement unit 31 can receive temperature values, which are the result of the temperature sensor measuring the temperature of the battery 10 at predetermined time intervals or in real time, extract temperature data corresponding to a predetermined diagnostic time point, and transmit it to the control unit 35.

[0075] Next, the control unit 35 extracts multiple prior diagnostic time points corresponding to the sample size (SN) based on the current diagnostic time point (N) to determine the sample population (S200).

[0076] Referring to Table 1, the control unit 35 can determine the sample population by counting the diagnostic time points in the direction of previous diagnostic time points, starting from the current diagnostic time point (N), and extracting the N-5th, N-4th, N-3rd, N-2nd, and N-1st diagnostic time points, which correspond to 5 samples in the sample size (SN).

[0077] The control unit 35 extracts a plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1) to determine a sample population, and the temperature values (T N-5 , T N-4 , T N-3 , T N-2 , T N-1 ) measured at each of the plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population can be used to calculate a thermal-overheat reference value (Th N ). By calculating the thermal-overheat reference value (Th N ) in the method described below, it is possible to prevent the problem of misdiagnosing the temperature rise due to battery aging as the occurrence of a thermal-overheat event. Also, it is possible to solve the problem of misdiagnosing a temporary temperature rise as the occurrence of a thermal-overheat event due to various causes.

[0078] Next, the control unit 35 calculates a thermal-overheat reference value (Th N-5 , T N-4 , T N-3 , T N-2 , T N-1 ) corresponding to the Nth diagnosis time point based on the plurality of temperature values (T N ) measured at each of the plurality of diagnosis time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population (S300).

[0079] In step S300, referring to FIG. 4, the control unit 35 averages the plurality of temperature values corresponding to each of the plurality of diagnosis time points belonging to the sample population to calculate a moving average value (MA N ) corresponding to the Nth diagnosis time point (S310).

[0080] Specifically, referring to Table 1, the control unit 35 averages the plurality of temperature values (29.4°C, 29.3°C, 29.​​​​ At stage S300, the control unit 35 averages the multiple standard deviations corresponding to each of the multiple diagnostic time points belonging to the sample population to obtain the mean standard deviation (SD). N Calculate the average standard deviation (SD) N Based on _ave), the error value (ER N Calculate (S330).

[0082] Specifically, as shown in Table 3, the control unit 35 calculates multiple standard deviations (SD) corresponding to multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population. N-5 SD N-4 SD N-3 SD N-2 SD N-1 Based on this, the mean standard deviation (SD) corresponding to the Nth diagnostic time point. N _ave (0.07442) can be calculated.

[0083] The control unit 15 calculates the standard deviation mean (SD) using the formula (2) above. N Multiply the _ave) by a predetermined multiple (α) to get the error value (ER N ) can be calculated. At this time, the multiple (α) can be determined to a variety of values ​​by experiment. Hereafter, we will assume that the multiple (α) is a natural number 3 (α=3). For example, referring to Table 3 and the above formula (2), the control unit 15 can calculate the mean standard deviation (SD N Multiply _ave=0.07442) by a multiple (α=3) to get the error value (ER N )0.22326 can be calculated.

[0084] At stage S300, the control unit 35 calculates the error value (ER N ) and a predetermined error standard value (TH N Compare with _ER) (S350).

[0085] Error value (ER N The error value (ER) is a value that reflects the errors that can occur in various situations, such as temperature measurement. N If ) is very small, the moving average (MA) NThe interval between the temperature (T) measured at the Nth diagnostic point and the overheat threshold (Th) can be very narrow. In other words, even if an overheat event has not actually occurred, the temperature (T) measured at the Nth diagnostic point may be very narrow. N The value of (Th) is the overheating standard value calculated at the Nth diagnostic stage. N ) arithmetic calculations exceeding a certain threshold can lead to a misdiagnosis of an overheating event. In other words, if the error value (ER) that forms the basis for calculating the overheating threshold (Th) is smaller than the generally expected value, there is a high probability of a misdiagnosis.

[0086] At stage S300, the result of the above comparison is the error value (ER N ) is the error standard value (TH N If it is smaller than _ER, the control unit 15 corrects the temperature value (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 (S370).

[0087] For example, the error threshold (TH N _ER) is the moving average (MA N It can be calculated as a value corresponding to 1% of (29.38℃ × 0.01 = 0.2938), but it is not limited to this, and a variety of values ​​can be determined.

[0088] In step S370, referring to Figure 4, the control unit 15 extracts multiple temperature values ​​corresponding to multiple 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 the moving average value (MA) for each of the multiple temperature values. N Compare with (S372).

[0090] For example, for each of the multiple temperature values, the control unit 15 calculates the moving average value (MA) of the temperature value. N It is possible to determine whether it is above )

[0091] At stage S370, as a result of the comparison, the temperature value is calculated as a moving average (MA NIf the temperature is above (S372, YES), the control unit 15 corrects the temperature value by adding a predetermined correction value (β) to the temperature value (S373).

[0092] At stage S370, as a result of the comparison, the temperature value is calculated as a moving average (MA N If it is smaller than (S372, NO), the control unit 15 corrects the temperature value by subtracting the correction value (β) from the temperature value (S374).

[0093] For example, referring to Table 1 above, the moving mean (MA) of multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population can be found. 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-5, N-3, and N-1 diagnostic time points corresponding to temperatures of 29.38°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 a 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 below 29.38°C. As a result, the temperature values ​​of 29.4°C, 29.3°C, 29.4°C, 29.3°C, and 29.5°C at 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, respectively.

[0094] Referring to Figures 4 and 5, the control unit 15 repeats steps S310 and S330 according to the corrected temperature values ​​(T') 31.4°C, 27.3°C, 31.4°C, 27.3°C, and 31.5°C for each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1), and calculates the corrected moving average value (MA). N ') and corrected error value (ER N ') can be recalculated. Then, as a result of the S350 stage judgment, the corrected error value (ER N ') is the corrected error reference value (TH NIf it is greater than _ER' (S350, YES), then the process can proceed to step S390. In other words, steps S370, S310, and S330 can be repeated until the result of the judgment 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] At step S370, the control unit 15 determines whether all of the multiple temperature values ​​corresponding to each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) belonging to the sample population have been corrected (S375).

[0096] If, as a result of the judgment in step S370, there is an uncorrected temperature value among the multiple temperature values ​​(S375, NO), the control unit 15 repeats from step S372.

[0097] At step S370, if the result of the above determination is that the correction of all multiple temperature values ​​belonging to the sample population is completed (S375, YES), the control unit 15 adjusts the corrected multiple 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. N-5 ', T N-4 ', T N-3 ', T N-2 ', T N-1 The correction can be completed by storing the ') in the storage unit 33 (S376).

[0098] In one embodiment, even if the temperature value is corrected by step S370 at the Nth diagnostic time, the multiple temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) measured at each of the multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1) and pre-stored in the storage unit 33 do not need to be corrected. In other words, even if the temperature value is corrected by step S370 at the Nth diagnostic time, the corrected moving average value (MA) does not need to be corrected. N ') and corrected error value (ER N Based on '), the corrected overheating threshold value (Th NOnly this can be calculated.

[0099] In other embodiments, if the temperature value is corrected by step S370 at the Nth diagnostic time, the multiple temperature values ​​(29.4°C, 29.3°C, 29.4°C, 29.3°C, 29.5°C) measured at each of the multiple 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 multiple temperature values ​​(31.4°C, 27.3°C, 31.4°C, 27.3°C, 31.5°C). Therefore, at subsequent N+1th diagnostic time points, N+2nd diagnostic time points, etc., the moving average value (MA) can be calculated. N+1 MA N+2 (etc.) and corrected error value (ER N+1 +ER N+2 When calculating (etc.), the calculation can be performed based on multiple temperature values ​​corrected at the Nth diagnostic point.

[0100] At step S300, referring again to Figure 4, the control unit 15 sets the moving average value (MA N or MA N ') Error value (ER N or ER N Add ') to obtain the overheating threshold value (Th N or Th N Calculate ') (S390).

[0101] For example, if the temperature values ​​(T) at multiple 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) based on the corrected temperature values ​​(T') at multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1). N ') and corrected error value (ER N Add ') to obtain the corrected overheating threshold value (Th N ') can be calculated. For example, the corrected overheating threshold value (Th) can be calculated based on the temperature values ​​(T') of each of the corrected multiple diagnostic time points (N-5, N-4, N-3, N-2, N-1). N Let's assume the temperature is 32.5℃.

[0102] Next, referring again to Figure 3, the control unit 35 measures the temperature (T) measured at the Nth diagnostic time. N ) value and overheating standard value (Th N ) is compared with the above to diagnose whether or not an overheating event has occurred in battery 10 (S400).

[0103] At step S400, the control unit 35 determines the temperature (T) measured at the Nth diagnostic time. N ) The value is the overheating standard value (Th N Determine whether it exceeds (S410).

[0104] At the S400 stage, as a result of the above determination, the temperature (T N ) The value is the overheating standard value (Th N If the value exceeds (S410, Yes), the control unit 35 diagnoses that an overheating event has occurred in the battery 10 (S420).

[0105] At the S400 stage, as a result of the above determination, the temperature (T N ) The value is the overheating standard value (Th N If the value is below (S400, NO), the control unit 35 diagnoses the temperature of the battery 10 as normal (S430).

[0106] For example, referring to Table 1, the temperature measured at the Nth diagnostic point (T N Let's assume the value is 30°C. The temperature (T) corresponding to the Nth diagnostic time point. N The value (30℃) corresponds to the overheating standard value (Th) at the Nth diagnostic point. N Since it is less than 32.5℃, the control unit 35 can diagnose that no overheating event has occurred. In other words, the control unit 35 can diagnose that the object's temperature is in a normal state.

[0107] Figure 6 is an example diagram showing the temperature change of a battery without defects in charging mode, and Figure 7 is an example diagram showing the temperature change of a battery with defects in charging mode.

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

[0109] Figure 6 illustrates the temperature change over time when a defect-free battery is charged at various external temperatures.

[0110] For example, in a charging mode where the battery 10 is charged by the power of an external device when the ambient temperature is 25°C, the temperature change of the battery 10 over time is shown in Graph T1. A This can be addressed. As another example, when the ambient temperature is 30°C and the battery 10 is being charged, the temperature change of the battery 10 over time is shown in the second graph T. B This can be addressed. Similarly, the temperature change of battery 10 at ambient temperatures of 35°C and 40°C, respectively, is shown in the third graph T C and the fourth graph T D It can handle this.

[0111] In other words, in the case of a battery 10 that is in a normal state according to a predetermined standard or a new, unused battery 10, the starting temperature value may differ if the external temperature changes, but as shown in Figure 6, the temperature change over time (i.e., the slope) may remain constant.

[0112] Referring to Figure 7, this is an illustrative diagram showing the temperature change over time when a defective battery is charged at a given external temperature, and it is a graph derived from experiments.

[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, is the reference line. The reference line may be constructed by connecting the overheating reference values ​​calculated for each diagnostic point according to the embodiment. Referring to Figures 6 and 7, the temperature change of a non-defective battery forms a linear graph as shown in Figure 6, while the temperature change of a defective battery can form a curved graph as shown in Figure 7.

[0114] Conventionally, if the temperature of the battery 10 exceeded a fixed overheating threshold (e.g., 60°C), the occurrence of an overheating event was diagnosed at that point. Referring to Figure 7, conventionally, the occurrence of an overheating event of the battery 10 could be diagnosed for the first time 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 threshold value (e.g., 60°C). In the experiment, the occurrence of an overheating event for the battery 10 was first diagnosed at the first time point AD1. Specifically, the diagnosis showed that overheating events were continuously diagnosed at each diagnostic time point from the first time point AD1, when the solid line FL crossed the dotted line DL, to the second time point AD2.

[0116] Referring to Figure 7, the experimental results showed a time difference of approximately 1000 seconds (approximately 16 minutes) between the first time point AD1 and the second time point AD2. The overheating diagnosis method according to this embodiment has the advantage that the occurrence of an overheating event of the battery 10 can be known in advance, and countermeasures can be taken against it.

[0117] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modified and improved forms by persons with ordinary skill in the art to which the present invention belongs also fall within the scope of the present invention.

Claims

1. A measuring unit that measures the temperature of an object, The measuring unit includes a storage unit for storing the temperature value measured by the measuring unit, An overheating diagnostic device comprising: a control unit that, for each diagnostic time point in which overheating of the object is diagnosed, extracts multiple diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average value which is the average of multiple temperature values ​​corresponding to each of the multiple diagnostic time points, calculates a standard deviation average value which is the average of multiple standard deviations corresponding to each of the multiple diagnostic time points, and if the error value calculated by multiplying the standard deviation average value by a predetermined multiple is greater than or equal to a predetermined error standard value, adds the error value to the moving average value to calculate an overheating standard value, and compares the temperature value measured for each diagnostic time point with the overheating standard value calculated for each diagnostic time point to diagnose the occurrence of an overheating event for the object.

2. The overheating diagnostic device according to claim 1, wherein the control unit corrects the plurality of temperature values ​​according to the 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, and calculates the overheating reference value based on the corrected plurality of temperature values.

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

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

5. A battery containing multiple battery cells, A measuring unit for measuring the temperature of the battery, The measuring unit includes a storage unit for storing the temperature value measured by the measuring unit, A battery system including a control unit that, for each diagnostic time point used to diagnose overheating of the battery, extracts a plurality of diagnostic time points corresponding to a predetermined number of samples based on the diagnostic time point, calculates a moving average value which is the average of a plurality of temperature values ​​corresponding to each of the plurality of diagnostic time points, calculates a standard deviation mean which is the average of a plurality of standard deviations corresponding to each of the plurality of diagnostic time points, and if the error value calculated by multiplying the standard deviation mean by a predetermined multiple is greater than or equal to a predetermined error standard value, adds the error value to the moving average value to calculate an overheating standard value, and diagnoses the occurrence of an overheating event in the battery by comparing the temperature value measured for each diagnostic time point with the overheating standard value calculated for each diagnostic time point.

6. The battery system according to claim 5, wherein the control unit corrects the plurality of temperature values ​​according to the 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, and calculates the overheat reference value based on the corrected plurality of temperature values.

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 a 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 threshold value.

9. At a predetermined diagnostic point for diagnosing overheating of a battery containing multiple battery cells, a temperature data acquisition step is performed in which a temperature value, which is a temperature measurement of the battery, is received from the measurement unit. A sample group determination stage in which multiple diagnostic time points corresponding to the sample size are extracted based on the aforementioned diagnostic time point, A step to calculate an overheating reference value includes: calculating a moving average value which is the average of multiple temperature values ​​corresponding to each of the multiple diagnostic time points; calculating a standard deviation average value which is the average of multiple standard deviations corresponding to each of the multiple diagnostic time points, and calculating an error value by multiplying the standard deviation average value by a predetermined multiple; and if the calculated error value is equal to or greater than a predetermined error reference value, calculating an overheating reference value by adding the error value to the moving average value. An overheating diagnostic method comprising: an overheating diagnostic step of comparing the temperature value with the overheating reference value to diagnose the occurrence of an overheating event in the battery.

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

11. The aforementioned temperature value correction step is The step of extracting multiple temperature values ​​corresponding to each of the aforementioned multiple diagnostic time points, A step of comparing each of the aforementioned multiple temperature values ​​with the moving average value, As a result of the above comparison, if the temperature value is equal to or greater than the moving average value, a first correction step is performed to correct the temperature value by adding a predetermined correction value to the temperature value. The overheating diagnosis 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 aforementioned overheating diagnosis step is: A step of comparing the measured temperature value with the overheating reference value, If the measured temperature value exceeds the overheating threshold as a result of the comparison, a first diagnostic step is performed in which it is diagnosed that an overheating event has occurred in the battery. The overheating diagnosis method according to claim 9, further comprising a second diagnostic step of diagnosing that, as a result of the comparison, if the measured temperature value is below the overheating threshold value, the battery is in a normal state and no overheating event has occurred.

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