Battery controller, battery pack, electric vehicle, and battery diagnosis method

Abstract

SOLUTION: A battery controller according to the present disclosure includes a memory in which a battery diagnosis program is recorded, and a processor configured to execute the battery diagnosis program. When the battery diagnosis program is executed by the processor, the processor is configured to determine a long term average voltage value and a short term average voltage value by applying a first average filter having a first time length and a second average filter having a second time length shorter than the first time length to a voltage value indicating a cell voltage of the battery cell, and determine an abnormality of the battery cell by comparing a voltage deviation, which is a difference between the long term average voltage value and the short term average voltage value, with at least one of a first threshold deviation and a second threshold deviation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2021-0091231, filed on July 12, 2021, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings of that application.

[0002] The present invention relates to a technique for diagnosing abnormalities in battery cells. [Background technology]

[0003] In recent years, as demand for portable electronic products such as laptops, video cameras, and mobile phones has grown rapidly and the development of electric vehicles, energy storage batteries, robots, and artificial satellites has gained momentum, active research is being conducted into high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently, batteries such as nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries are commercially available, but lithium batteries are attracting attention due to their advantages of being free to charge and discharge without experiencing any memory effect compared to nickel-based batteries, having a very low self-discharge rate, and having a high energy density.

[0005] In recent years, applications requiring high voltages (e.g., electric vehicles, energy storage systems) have become widespread, increasing the need for diagnostic technology that can accurately detect abnormalities in each of the multiple battery cells connected in series within a battery pack.

[0006] Conventionally, a method has been adopted in which a state parameter (e.g., cell voltage) of each battery cell is compared with a state parameter of at least one of the other battery cells to detect an abnormality in each battery cell. However, this method has the disadvantages of (i) requiring a large amount of software resources (computational load) and time to individually diagnose an abnormality in all battery cells because a comparison process must be performed as many times as there are battery cells, and (ii) increasing the possibility of misdiagnosis as the number of abnormal battery cells among the battery cells increases. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems, and aims to provide a battery controller, a battery pack, an electric vehicle, and a battery diagnosis method that, in diagnosing an abnormality in a single battery cell or each of a plurality of battery cells connected in series, diagnoses an abnormality in the corresponding battery cell by utilizing a change in the cell voltage of each battery cell over time, without a process of comparing the cell voltage of each battery cell with the cell voltages of other battery cells.

[0008] Other objects and advantages of the present invention will become apparent from the following description and the embodiments of the present invention, and can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0009] A battery controller according to one aspect of the present invention includes a memory having a battery diagnostic program recorded therein, and a processor configured to execute the battery diagnostic program. When the battery diagnostic program is executed by the processor, the processor is configured to: determine a long-term average voltage value and a short-term average voltage value by applying a first averaging filter of a first time length and a second averaging filter of a second time length shorter than the first time length to voltage values ​​indicating cell voltages of battery cells; determine a voltage deviation that is a difference between the long-term average voltage value and the short-term average voltage value; and compare the voltage deviation with at least one of a first critical deviation and a second critical deviation to determine an abnormality of the battery cell.

[0010] The first critical deviation may be a positive number, and the second critical deviation may be a negative number having an absolute value equal to that of the second critical deviation.

[0011] The processor may be configured to determine that the battery cell is abnormal if the voltage deviation is greater than the first critical deviation or less than the second critical deviation.

[0012] The processor may be configured to determine a current change amount, which is the difference between a maximum current value and a minimum current value among current values ​​indicating the current of the battery cell measured over the same period as the cell voltage, and determine the long-term average voltage value and the short-term average voltage value on the condition that the current change amount is less than a critical change amount.

[0013] A battery pack according to another aspect of the present invention includes the above-described battery controller.

[0014] An electric vehicle according to yet another aspect of the present invention includes the battery pack described above.

[0015] According to yet another aspect of the present invention, a battery diagnosis method includes determining a long-term average voltage value and a short-term average voltage value by applying a first averaging filter of a first time length and a second averaging filter of a second time length shorter than the first time length to a plurality of voltage values ​​indicating cell voltages of battery cells; determining a voltage deviation which is a difference between the long-term average voltage value and the short-term average voltage value; and comparing the voltage deviation with at least one of a first critical deviation and a second critical deviation to determine an abnormality in the battery cells.

[0016] The determining whether the battery cell is abnormal may include determining that the battery cell is abnormal if the voltage deviation is greater than the first critical deviation or less than the second critical deviation.

[0017] The battery diagnosis method may further include determining a current change amount, which is a difference between a maximum current value and a minimum current value among current values ​​indicating currents of the battery cell measured over the same period as the cell voltage. The determining of the long-term average voltage value and the short-term average voltage value may be performed on the condition that the current change amount is less than a critical change amount. [Effects of the Invention]

[0018] According to at least one aspect of the present invention, in diagnosing an abnormality in a single battery cell or each of a plurality of battery cells connected in series, the abnormality in the corresponding battery cell can be diagnosed by utilizing a change in the cell voltage of each battery cell over time without a process of comparing the cell voltage of each battery cell with the cell voltages of the other battery cells. Therefore, it is possible to save software resources and time required to diagnose an abnormality in each battery cell, and at the same time, it is possible to reduce the possibility of misdiagnosis due to an increase in abnormal battery cells among the plurality of battery cells.

[0019] According to at least one aspect of the present invention, by determining the difference between the long-term trend and the short-term trend of the cell voltage of each battery cell, measurement noise contained in the measured value of the cell voltage of the corresponding battery cell can be effectively removed, and abnormal changes in the cell voltage of the corresponding battery cell can be accurately detected.

[0020] The effects of the present invention are not limited to the above-mentioned effects, and other effects will be clearly understood by those skilled in the art from the description of the claims.

[0021] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram illustrating an example of the configuration of an electric vehicle according to the present invention; [Figure 2] 1 is a graph showing an example of a voltage curve corresponding to a raw time series of actual voltage values ​​of a cell voltage of a battery cell. [Figure 3] 3 is a graph showing an example of a measured voltage curve obtained by combining measurement noise with a primitive time series corresponding to the voltage curve of FIG. 2; [Figure 4] 4 is a graph showing an example of a first moving average curve obtained by applying a first average filter to the voltage curve of FIG. 3; [Figure 5] 4 is a graph showing an example of a second moving average curve obtained by applying a second average filter to the voltage curve of FIG. 3. [Figure 6] 6 is a graph showing an example of a voltage deviation curve that is the difference between the first moving average curve of FIG. 4 and the second moving average curve of FIG. 5. [Figure 7] 1 is a flow chart illustrating an example of a battery diagnostic method according to a first embodiment of the present invention. [Figure 8]FIG. 6 is a flow chart illustrating an example of a battery diagnostic method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best explain the invention.

[0024] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0025] Terms including ordinal numbers such as first, second, etc. are used to distinguish one of various components from the other components, and do not limit the components.

[0026] Throughout the specification, when a part "includes" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified. Furthermore, terms such as "control circuit" described in the specification refer to a unit that processes at least one function or operation, and may be embodied in hardware, software, or a combination of hardware and software.

[0027] Furthermore, throughout this specification, when a part is referred to as being "connected" to another part, this includes not only a "direct connection" but also an "indirect connection" via other elements.

[0028] FIG. 1 is a diagram showing an example of the configuration of an electric vehicle according to the present invention.

[0029] 1, an electric vehicle 1 includes a vehicle controller 2, a battery pack 10, an inverter 30, and an electric motor 40. Charging and discharging terminals P+ and P- of the battery pack 10 may be electrically coupled to a charger 3 via a charging cable or the like. The charger 3 may be included in the electric vehicle 1 or may be provided at a charging station.

[0030] The vehicle controller 2 (e.g., an ECU: Electronic Control Unit) is configured to transmit a key-on signal to the battery diagnostic device 100 in response to a start button (not shown) provided on the electric vehicle 1 being turned to an on position by a user. The vehicle controller 2 is configured to transmit a key-off signal to the battery diagnostic device 100 in response to a start button being turned to an off position by a user. The charger 3 communicates with the vehicle controller 2 and can supply constant current or constant voltage charging power through the charge / discharge terminals P+ and P- of the battery pack 10. The charger 3 may have a discharge function and, prior to the start of a first charging stage S1 (described later), can discharge the battery 11 in response to a request from the vehicle controller 2 so that the battery voltage (e.g., OCV: Open Circuit Voltage) of the battery 11 becomes equal to or lower than a predetermined reference voltage.

[0031] The battery pack 10 includes a battery 11 , a relay 20 and a battery diagnostic device 100 .

[0032] The battery 11 includes at least one battery cell BC. In FIG. 1, the battery 11 includes a plurality of battery cells BC1 to BC2 connected in series. N (N is a natural number of 2 or more) are illustrated as including a plurality of battery cells BC1 to BC N The battery cells BC1 to BC2 may be provided to have the same electrochemical specifications. NWhen describing the contents common to all of the above, the battery cells will be denoted by the reference symbol "BC."

[0033] The type of battery cell BC is not particularly limited as long as it can be repeatedly charged and discharged, such as a lithium ion cell.

[0034] The relay 20 is electrically connected in series with the battery 11 through a power path connecting the battery 11 and the inverter 30. FIG. 1 shows the relay 20 connected between the positive terminal of the battery 11 and the charge / discharge terminal P+. The relay 20 is controlled to be turned on and off in response to a switching signal from the battery diagnostic device 100. The relay 20 may be a mechanical contactor that is turned on and off by the magnetic force of a coil, or may be a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0035] The inverter 30 is provided to convert DC current from the battery 11 included in the battery pack 10 into AC current in response to commands from the battery diagnostic device 100 or the vehicle controller 2. The electric motor 40 is driven using AC power from the inverter 30. A three-phase AC motor, for example, may be used as the electric motor 40. The components in the electric vehicle 1 that receive the discharge power of the battery 11, including the inverter 30 and the electric motor 40, may be collectively referred to as an electric load.

[0036] The battery diagnostic device 100 includes a voltage detector 110 and a control circuit 140. The battery diagnostic device 100 may further include at least one of a current detector 120, a temperature detector 130, and a communication circuit 150.

[0037] The voltage detector 110 is connected to the positive and negative terminals of the battery cell BC, and is configured to measure a cell voltage, which is a voltage applied across the battery cell BC, and generate a voltage signal indicating the measured cell voltage. The voltage detector 110 may be implemented as one or a combination of two or more known voltage detection elements, such as a voltage measurement integrated circuit (IC).

[0038] The current detector 120 is connected in series to the battery 11 through a current path between the battery 11 and the inverter 30. The current detector 120 is configured to measure a battery current (also referred to as a "charge / discharge current") flowing through the battery 11 and generate a current signal indicative of the measured battery current. N are connected in series, multiple battery cells BC1 to BC N The battery current flowing through any of the battery cells is the same as the battery current flowing through the other battery cells. The current detector 120 may be implemented using one or a combination of two or more known current detection elements such as a shunt resistor, a Hall effect element, etc.

[0039] The temperature detector 130 is configured to measure the battery temperature, which is the temperature of the battery 11, and generate a temperature signal indicative of the measured battery temperature. The temperature detector 130 may be implemented using one or a combination of two or more known temperature detection elements such as a thermocouple, a thermistor, a bimetal, etc.

[0040] The communication circuit 150 is configured to support wired or wireless communication between the control circuit 140 and the vehicle controller 2. The wired communication may be, for example, CAN (controller area network) communication, and the wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control circuit 140 and the vehicle controller 2. The communication circuit 150 may include an output device (e.g., a display, a speaker) that provides information received from the control circuit 140 and / or the vehicle controller 2 in a form that can be recognized by a user (driver).

[0041] The control circuit 140 is operably coupled to the relay 20, the voltage detector 110, and the communication circuit 150. When two components are operably coupled, it means that the two components are directly or indirectly connected so that signals can be sent and received in one or both directions.

[0042] The control circuit 140 may collect the voltage signal from the voltage detector 110, the current signal from the current detector 120, and / or the temperature signal from the temperature detector 130. That is, the control circuit 140 may convert and record each analog signal collected from the sensors (110, 120, 130) into a digital value using an analog-to-digital converter (ADC) provided inside the control circuit 140. Alternatively, the voltage detector 110, the current detector 120, and the temperature detector 130 may each include an ADC inside and transmit the digital value to the control circuit 140.

[0043] The control circuit 140, also referred to as a "battery controller," may be implemented in hardware using at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), microprocessors, and other electrical units for performing functions.

[0044] The memory 141 may include at least one form of recording medium, for example, a flash memory, a hard disk, a solid state disk (SSD), a silicon disk drive (SDD), a multimedia microcard, a random access memory (RAM), a static RAM (SRAM), a read only memory (ROM), an electrically erasable programmable ROM (EEPROM), or a programmable ROM (PROM). The memory 141 may store data and programs necessary for the calculation operations of the control circuit 140. The memory 141 may store data indicating the results of the calculation operations of the control circuit 140. The memory 141 may store data sets and software used to determine an abnormality in the battery cell BC. The memory 141 may be integrated into the control circuit 140.

[0045] If the relay 20 is turned on while the electrical loads (30, 40) and / or the charger 3 are operating, the battery 11 is in charging mode or discharging mode. If the relay 20 is turned off while the battery 11 is being used in charging mode or discharging mode, the battery 11 is switched to rest mode.

[0046] The control circuit 140 may turn on the relay 20 in response to a key-on signal. The control circuit 140 may turn off the relay 20 in response to a key-off signal. The key-on signal is a signal requesting a switch from a rest state to charging or discharging. The key-off signal is a signal requesting a switch from charging or discharging to a rest state. Alternatively, the on / off control of the relay 20 may be performed by the vehicle controller 2 instead of the control circuit 140.

[0047] 1, the battery diagnostic device 100 is included in a battery pack 10 for an electric vehicle 1, but this should be understood as an example. That is, the battery diagnostic device 100 may be included in a test system used to screen out abnormal battery cells in the manufacturing process of battery cells BC.

[0048] FIG. 2 is a graph showing an example of a voltage curve corresponding to an original time series of actual voltage values ​​of cell voltages of a battery cell, FIG. 3 is a graph showing an example of a measured voltage curve obtained by combining measurement noise with an original time series corresponding to the voltage curve of FIG. 2, FIG. 4 is a graph showing an example of a first moving average curve obtained by applying a first averaging filter to the voltage curve of FIG. 3, FIG. 5 is a graph showing an example of a second moving average curve obtained by applying a second averaging filter to the voltage curve of FIG. 3, and FIG. 6 is a graph showing an example of a voltage deviation curve which is the difference between the first moving average curve of FIG. 4 and the second moving average curve of FIG. 5.

[0049] First, referring to FIG. 2, a voltage curve 200 is shown for a predetermined period t1 to t M 1 is an example of a primitive time series containing the actual voltage values ​​of the cell voltage of the battery cell BC when charging over a period of time t1. To facilitate understanding, the cell voltage increases linearly and is different from the period before t2 to t3. M The actual voltage values ​​for the subsequent periods are not shown.

[0050] When a battery cell BC is normal, its cell voltage increases gradually and continuously during charging. However, if the battery cell BC is in an abnormal state due to an internal fault (e.g., a micro-short circuit or a broken portion of the electrode tab), the cell voltage may exhibit irregular behavior, such as a sudden drop or rise, even during charging. The voltage curve 200 in FIG. 2 is related to an abnormality in the battery cell BC, with region X indicating the time range in which the cell voltage drops abnormally and region Y indicating the time range in which the cell voltage rises abnormally. While FIG. 2 illustrates the cell voltage during charging, the cell voltage of an abnormal battery cell may also change abnormally during discharging or resting. For example, during discharging, the cell voltage of a normal battery cell may decrease gradually and continuously, while the cell voltage of an abnormal battery cell may temporarily rise or fall suddenly.

[0051] Referring now to FIG. 3, voltage curve 300 shows the result of adding measurement noise to the actual cell voltage of voltage curve 200 of FIG. 2, i.e., a time series of voltage values ​​indicating the measured cell voltages arranged in chronological order. Let M be a natural number indicating a predetermined total number of samplings (e.g., 300) and K be a natural number less than or equal to M, then t K is the K-th voltage value (V m [K]) measurement timing (Kth measurement timing t K ), and the time interval between two adjacent measurement timings is a predetermined sampling time (e.g., 0.1 seconds). m [K]) is the voltage value at measurement timing t among the total M voltage values ​​included in the voltage curve 300. K are data points indexed by

[0052] The measurement noise may occur irregularly over time due to internal and external factors of the voltage detector 110 (e.g., the temperature of the voltage detector, the sampling rate, electromagnetic waves, etc.). M 1 is a time series containing current values ​​of the battery current measured over a predetermined period t1 to t2.M This is an example of something that is constant within the

[0053] 3. Comparing the voltage curve 300 of FIG. 3 with the voltage curve 200 of FIG. 2, the abnormal behavior (X, Y) can be easily identified from the voltage curve 200 without measurement noise of FIG. 2, while the abnormal behavior (X, Y) can be easily identified from the voltage curve 200 without measurement noise of FIG. 3. M There is a problem in that it is difficult to identify abnormal behavior (X, Y) from the voltage curve 300 in which measurement noise is mixed throughout.

[0054] The inventors have confirmed that the above-mentioned problem can be solved by applying a first averaging filter and a second averaging filter to a time series (300) of voltage values ​​(measured values) that includes measurement noise generated at the timing of cell voltage measurement. The time series of voltage values ​​acquired over a predetermined period of time in the past for a battery cell BC to be diagnosed may be referred to as a "reference voltage curve," and the time series of current values ​​may be referred to as a "reference current curve." In the following description, the voltage curve 300 and the current curve 310 are assumed to be the reference voltage curve and the reference current curve, respectively.

[0055] First, the control circuit 140 may determine a plurality of sub-voltage curves by applying a moving window of a first time length to the reference voltage curve 300. Furthermore, the control circuit 140 may determine a plurality of sub-current curves that correspond one-to-one to the plurality of sub-voltage curves by applying a moving window of a first time length to the reference current curve 310.

[0056] If K is a natural number equal to or less than M, a total of M sub-voltage curves (i.e., the first to Mth sub-voltage curves) can be determined from the reference voltage curve 300. The reference voltage curve 300 includes a total of M voltage values ​​(i.e., the first to Mth voltage values) measured sequentially at each sampling time W. The sub-voltage curves S K The sub-voltage curve S includes (A / W+1) voltage values ​​that are consecutive in time order as a subset of the reference voltage curve 300. For example, if the sampling time W is 0.1 seconds and the first time length A is 10 seconds, the sub-voltage curve S Kis a time series of 101 voltage values ​​in total, namely, the (KP)th voltage value to the (K+P)th voltage value. P=A / 2W=50.

[0057] In Figure 3, R K is the sub-voltage curve S K Therefore, the subcurrent curve R K may also include (A / W+1) data points (current values) consecutive in time order.

[0058] The greater the battery current fluctuation, the greater the cell voltage fluctuation. The sudden fluctuation of the cell voltage due to the battery current becomes an obstacle to identifying the abnormal behavior of the cell voltage from the reference voltage curve 300. Therefore, the control circuit 140 calculates the sub-current curve R K The current change amount of the sub-voltage curve S is below the critical change amount. K The calculation process described below can be performed on the sub-current curve R K The current change amount of the sub-current curve R K The present invention is suitable for diagnosing abnormalities in battery cells from a time series of cell voltages measured during periods with small fluctuations in battery current, such as constant current charging or resting.

[0059] 4, the first average voltage curve 400 is obtained by applying a first averaging filter of a first time length A to the reference voltage curve 300. The first averaging filter is a type of low-pass filter, and may be a centered moving average having a subset size (A / W+1) corresponding to the first time length A. As an example, the control circuit 140 may generate a sub-voltage curve S K The (A / W+1) voltage values ​​included in the (A / W+1) voltage value, i.e., the (KP) voltage value to the (K-1) voltage value, the K voltage value, and the (K+1) voltage value to the (K+P) voltage value are averaged, and the averaged voltage is measured at the measurement timing t K The long-term average voltage value V is indexed to av1Determine [K]. The following Equation 1 shows the first averaging filter.

[0060]

number

[0061] In Equation 1, V m [i] is the i-th voltage value included in the reference voltage curve 300, A is the first time length, W is the sampling time, P is A / 2W, V av1 [K] is the measurement timing t K The control circuit 140 can determine the first average voltage curve 400 of FIG. 4 by substituting 1 to M for K in Equation 1. The first time length A is predetermined as an integer multiple of the sampling time W. Therefore, the first time length A is the long-term average voltage value V av1 Indicates the size of the subset (A / W+1) used to calculate [K].

[0062] 5, the second average voltage curve 500 is obtained by applying a second averaging filter of a second time length B, which is shorter than the first time length A, to the reference voltage curve 300. The second averaging filter is a type of low-pass filter, and may be a centered moving average having a subset size (B / W+1) corresponding to the second time length B. As an example, the control circuit 140 may generate a sub-voltage curve S K The (B / W+1) voltage values ​​included in the (B / W+1) voltage value, i.e., the (KQ)th voltage value to the (K-1)th voltage value, the Kth voltage value, and the (K+1)th voltage value to the (K+Q)th voltage value are averaged, and the averaged voltage is measured at the measurement timing t K The short-term average voltage value V is indexed to av2 Determine [K]. Q = B / 2W. Short-term average voltage V av2 [K] is the sub-voltage curve S K A subset U of K The mean of the subset U K is the sub-voltage curve S K Time range t K-P ~t K+P While located within the time range t K-P ~t K+Pand center t K The time range t where K-Q ~t K+Q The voltage curve of the second averaging filter is shown in Equation 2 below.

[0063]

number

[0064] In Equation 2, V m [i] is the i-th voltage value included in the reference voltage curve 300, B is the second time length, W is the sampling time, Q is B / 2W, V av2 [K] is the measurement timing t K The control circuit 140 can determine the second average voltage curve 500 of FIG. 5 by substituting 1 through M into K in Equation 2 one by one. The second time length B is predetermined as an integer multiple of the sampling time W. Therefore, the second time length B is the short-term average voltage value V av2 Indicates the size of the subset (B / W+1) used to calculate [K].

[0065] When the first time length A is greater than the second time length B, each data point (i.e., long-term average voltage value) of the first average voltage curve 400 may be referred to as a "long-term average value," and each data point (i.e., short-term average voltage value) of the second average voltage curve 500 may be referred to as a "short-term average value." As an example, A may be 10 times B.

[0066] 6, the voltage deviation curve 600 is the result of subtracting one of the first average voltage curve 400 and the second average voltage curve 500 from the other. That is, the voltage deviation curve 600 is the result of subtracting the first average voltage curve 400 from the second average voltage curve 500 during a predetermined period t1 to t M The time series of the total M voltage deviations for the sub-voltage curve S K The voltage deviation ΔV [K] associated with the long-term average voltage value V av1 [K] and short-term average voltage value V av2 It is the value obtained by subtracting one of the two [K]. For example, ΔV[K]=V av2 [K]-V av1 [K].

[0067] As mentioned above, the long-term average voltage value V av1 [K] is the measurement timing t K is the average cell voltage for a long period of time A centered on av2 [K] is the measurement timing t K is the average cell voltage for a short period of time B centered on V. Therefore, the long-term average voltage value V av1 [K] and short-term average voltage value V av2 By subtracting one of the voltages [K] from the other to obtain the voltage deviation ΔV [K], the measurement timing t K This has the effect of effectively eliminating measurement noise that occurs over a certain period of time before and after the measurement.

[0068] Long-term average voltage V av1 [K] and short-term average voltage value V av2 Through the process of subtracting one side of [K] from the other, the measurement timing t K This has the advantage that measurement noise generated over a certain period before and after the measurement is canceled out to a considerable extent.

[0069] The control circuit 140 may compare the voltage deviation ΔV[K] with a first critical deviation TH1 and a second critical deviation TH2. The first critical deviation TH1 may be a predetermined positive number (e.g., +0.001 V), and the second critical deviation TH2 may be a predetermined negative number (e.g., −0.001 V) whose absolute value is equal to that of the first critical deviation TH1.

[0070] The control circuit 140 may determine that the battery cell BC is abnormal if a predetermined number (e.g., 10) or more of the voltage deviations included in the voltage deviation curve 600 are greater than the first critical deviation TH1 or less than the second critical deviation TH2.

[0071] The control circuit 140 may determine that the battery cell BC is abnormal if two of the M voltage deviations included in the voltage deviation curve 600 satisfy a first condition, a second condition, and a third condition. The first condition is satisfied when one of the two voltage deviations is equal to or greater than a first critical deviation TH1. The second condition is satisfied when the other of the two voltage deviations is equal to or less than a second critical deviation TH2. The third condition is satisfied when the time interval between the two voltage deviations is equal to or less than a critical time. The critical time may be predetermined to be less than a first time length A. Referring to FIG. 6, the voltage deviation ΔV[a] is equal to or less than the second critical deviation TH2 (satisfying the second condition), and the voltage deviation ΔV[b] is equal to or greater than the first critical deviation TH1 (satisfying the first condition). Therefore, if the time interval (Δt = tb - ta) between the two voltage deviations (ΔV[a], ΔV[b]) is equal to or less than the critical time, the battery cell BC is determined to be abnormal.

[0072] FIG. 7 is a flow chart illustrating an example of a battery diagnostic method according to a first embodiment of the present invention.

[0073] 1 to 7, in step S710, the control circuit 140 applies a moving window of a first time length A to the reference voltage curve 300 to determine a plurality of sub-voltage curves. The reference voltage curve 300 is moved over a predetermined period t1 to t M 1 is a time series of a plurality of voltage values ​​indicating the cell voltage of battery cell BC measured at each sampling time over a period of time.

[0074] In step S720, the control circuit 140 calculates the voltage of each of the plurality of sub-voltage curves S K Step S720 may include steps S722, S724, and S726 as substeps.

[0075] In step S722, the control circuit 140 calculates the sub-voltage curve S using a first averaging filter for a first time length A. K The long-term average voltage value V av1 Determine [K] (see Equation 1).

[0076] In step S724, the control circuit 140 calculates the sub-voltage curve S using a second averaging filter for a second time length B. K Short-term average voltage value V av2 Determine [K] (see Equation 2).

[0077] In step S726, the control circuit 140 calculates the long-term average voltage value V av1 [K] and short-term average voltage value V av2 Subtract one of the voltages [K] from the other to determine the voltage deviation ΔV [K].

[0078] In step S730, the control circuit 140 compares each of the plurality of voltage deviations determined for the plurality of sub-voltage curves with at least one of the first critical deviation and the second critical deviation to determine an abnormality of the battery cell BC. If the value of step S730 is 'YES', the control circuit 140 proceeds to step S740.

[0079] In step S740, the control circuit 140 generates a diagnostic message notifying that the battery cell BC is abnormal. The diagnostic message may be transmitted to the vehicle controller 2 and / or the user device via wired or wireless communication.

[0080] FIG. 8 is a flow chart illustrating an example of a battery diagnostic method according to a second embodiment of the present invention.

[0081] 1 to 6 and 8, in step S800, the control circuit 140 applies a moving window of a first time length A to the reference current curve 310 to determine a plurality of sub-current curves. The reference current curve 310 is moved over a predetermined period t1 to t M 1 is a time series of a plurality of current values ​​showing the battery current of battery cell BC measured at each sampling time over a period of time.

[0082] In step S810, the control circuit 140 determines a plurality of sub-voltage curves by applying a moving window of a first time length A to the reference voltage curve 300. Step S810 is the same as step S710.

[0083] In step S812, the control circuit 140 calculates the current for each sub-current curve R K Determine the amount of current change.

[0084] In step S820, the control circuit 140 selects each sub-current curve R among the plurality of sub-voltage curves, the sub-current curve R having a current change amount equal to or less than the critical change amount. K Each sub-voltage curve S associated with K Step S820 may include steps S722, S724, and S726 of FIG.

[0085] In step S830, the control circuit 140 compares each voltage deviation determined in step S820 with at least one of the first critical deviation and the second critical deviation to determine whether the battery cell BC is abnormal. If the result of step S830 is 'YES', the control circuit 140 proceeds to step S840.

[0086] In step S840, the control circuit 140 generates a diagnostic message indicating that the battery cell BC is abnormal.

[0087] The above-described embodiments of the present invention may be realized not only by an apparatus and a method, but also by a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such realization would be easily achievable by a person skilled in the art from the description of the above-described embodiments.

[0088] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims.

[0089] Furthermore, the present invention described above is susceptible to various substitutions, modifications, and alterations by a person having ordinary knowledge in the technical field to which the present invention pertains, within the scope that does not deviate from the technical concept of the present invention, and is not limited to the above-described embodiments and the accompanying drawings, but may be configured by selectively combining all or part of each embodiment for various modifications. [Explanation of symbols]

[0090] 1: Electric vehicles 2: Vehicle controller 10: Battery pack 11: Battery BC: Battery cell 100: Battery diagnostic device 110: Voltage detector 120: Current detector 140: Control circuit

Claims

1. a memory in which a battery diagnostic program is recorded; a processor configured to execute the battery diagnostic program; When the battery diagnosis program is executed by the processor, the processor applies a first averaging filter of a first time length and a second averaging filter of a second time length shorter than the first time length to a voltage value indicating a cell voltage of a battery cell to determine a long-term average voltage value and a short-term average voltage value, and determines a voltage deviation that is a difference between the long-term average voltage value and the short-term average voltage value; comparing the voltage deviation with at least one of a first critical deviation and a second critical deviation to determine an abnormality of the battery cell; The processor: applying the first averaging filter to a time range of the first length including a predetermined measurement timing to determine the long-term average voltage value at the measurement timing; applying the second averaging filter to a time range of the second length including the measurement timing to determine the short-term average voltage value at the measurement timing; The voltage deviation is a difference between the long-term average voltage value and the short-term average voltage value at the measurement timing.

2. the first critical deviation is a positive number, 2. The battery controller according to claim 1, wherein the second critical deviation is a negative number having an absolute value equal to that of the first critical deviation.

3. The processor: The battery controller according to claim 1 , wherein the battery controller determines that the battery cell is abnormal when the voltage deviation is greater than the first critical deviation or less than the second critical deviation.

4. The processor: determining a current change amount, which is a difference between a maximum current value and a minimum current value among current values ​​indicating the current of the battery cell measured over the same period as the cell voltage; The battery controller of claim 1 , wherein the long-term average voltage value and the short-term average voltage value are determined on the condition that the amount of change in current is less than a critical amount of change.

5. A battery pack comprising the battery controller according to any one of claims 1 to 4.

6. An electric vehicle comprising the battery pack of claim 5.

7. determining a long-term average voltage value and a short-term average voltage value by applying a first averaging filter of a first time length and a second averaging filter of a second time length shorter than the first time length to a plurality of voltage values ​​indicating cell voltages of the battery cells; determining a voltage deviation, which is the difference between the long-term average voltage value and the short-term average voltage value; comparing the voltage deviation with at least one of a first critical deviation and a second critical deviation to determine an abnormality of the battery cell; The step of determining the long-term average voltage value and the short-term average voltage value comprises: applying the first averaging filter to a time range of the first length including a predetermined measurement timing to determine the long-term average voltage value at the measurement timing; applying the second averaging filter to a time range of the second length including the measurement timing to determine the short-term average voltage value at the measurement timing; The battery diagnostic method, wherein the voltage deviation is a difference between the long-term average voltage value and the short-term average voltage value at the measurement timing.

8. The step of determining an abnormality in the battery cell includes: The battery diagnosis method of claim 7, further comprising determining that the battery cell is abnormal if the voltage deviation is greater than the first critical deviation or less than the second critical deviation.

9. determining a current change amount, which is a difference between a maximum current value and a minimum current value among current values ​​indicating the current of the battery cell measured over the same period as the cell voltage; 8. The battery diagnosis method of claim 7, wherein determining the long-term average voltage value and the short-term average voltage value is performed on the condition that the current change amount is less than a critical change amount.

10. determining a long-term average voltage value and a short-term average voltage value by applying a first averaging filter of a first time length and a second averaging filter of a second time length shorter than the first time length to a voltage value indicating a cell voltage of a battery cell; determining a voltage deviation, which is the difference between the long-term average voltage value and the short-term average voltage value; and an operation of comparing the voltage deviation with at least one of a first critical deviation and a second critical deviation to determine an abnormality of the battery cell, The operation of determining the long-term average voltage value and the short-term average voltage value comprises: applying the first averaging filter to a time range of the first length including a predetermined measurement timing to determine the long-term average voltage value at the measurement timing; applying the second averaging filter to a time range of the second length including the measurement timing to determine the short-term average voltage value at the measurement timing; The voltage deviation is a difference between the long-term average voltage value and the short-term average voltage value at the measurement timing.

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