Battery diagnostic device, battery diagnostic method, battery pack, and automobile

Abstract

A diagnostic control device according to an embodiment of the present invention includes a voltage sensing circuit, a recording medium, and a control circuit. The control circuit records first voltage time series data through Nth voltage time series data of a first battery cell through an Nth battery cell on the recording medium. The control circuit also selects a first voltage set measured at a first time and a second voltage set measured at a second time from the first voltage time series data through the Nth voltage time series data. The control circuit also determines coordinates <first time, average of the first voltage set> and coordinates <second time, average of the second voltage set> as a first average position vector and a second average position vector, respectively. The control circuit also determines a difference between the second average position vector and the first average position vector as a diagnostic reference vector. In addition, the control circuit determines the coordinates <first time, first voltage> and <second time, second voltage> as a first diagnostic position vector and a second diagnostic position vector for the i-th battery cell (i is 1 to N), determines the difference between the second diagnostic position vector and the first diagnostic position vector as the i-th diagnostic vector, determines an i-th diagnostic factor based on the magnitude of the cross product of the diagnostic reference vector and the i-th diagnostic vector, and diagnoses the i-th battery cell as having a voltage abnormality if the i-th diagnostic factor exceeds a critical value.

Description

[Technical Field]

[0001] The present invention relates to a technique for diagnosing voltage abnormalities in a battery.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0122317, filed on September 27, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof. [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 systems, robots, and artificial satellites has gained momentum, active research has been conducted into high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries are attracting attention due to their advantages of being able to be freely charged and discharged since they have almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and a high energy density.

[0005] In recent years, energy storage systems and electric vehicles that require high voltages have become widespread, and as a result, there is an increasing need for diagnostic technology that can accurately detect voltage abnormalities in each of the multiple battery cells connected in series within a battery pack.

[0006] Abnormal battery cell voltage refers to a fault condition in which the cell voltage drops and / or rises abnormally due to an internal short circuit, an external short circuit, a failure of the voltage sensing line, a poor connection with the charge / discharge line, or the like.

[0007] Conventionally, a simple method has been used to diagnose battery cell voltage abnormalities by determining whether the difference between cell voltages measured at two different points in time exceeds a critical value. This method has the advantage of not requiring a high-performance processor because it does not require a large amount of data calculations.

[0008] However, since the voltage of a battery cell also depends on the temperature, current, and / or SOH (State of Health), it is difficult to accurately diagnose abnormal battery cell voltage simply by comparing the voltage difference of the battery cell measured at different times with a critical value.

[0009] In addition, even if the voltage difference between battery cells is below the critical value, if the voltage gradient of the battery cells shows abnormal behavior, for example, if lithium plating occurs at the negative electrode of a lithium battery, there is a limitation in that the cell voltage abnormality cannot be detected. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery diagnostic device, a battery diagnostic method, a battery pack, and a vehicle for reliably diagnosing a battery cell having an abnormal voltage among a plurality of battery cells through simple mathematical calculations.

[0011] Other objects and advantages of the present invention can be understood from the following description and become more apparent from the embodiments of the present invention, and can be realized by the means and combinations thereof as set forth in the claims. [Means for solving the problem]

[0012] To achieve the above object, a battery diagnostic device according to one aspect of the present invention includes a voltage sensing circuit configured to generate voltage signals for each of a first battery cell to an Nth battery cell, a recording medium configured to record voltage time-series data, and a control circuit operably coupled to the voltage sensing circuit and the recording medium.

[0013] The control circuit (a) receives voltage signals from the voltage sensing circuit and records first to Nth voltage time series data of the first to Nth battery cells on a recording medium; (b) selects a first set of voltages measured at a first time and a second set of voltages measured at a second time after the first time from the first to Nth voltage time series data; and (c) determines a coordinate <first time, average of the first voltage set> as a first average position vector and a coordinate <second time, average of the second voltage set> as a second average position vector. (d) determine the difference between the second average position vector and the first average position vector as a diagnostic reference vector; (e) for the i-th battery cell (i is 1 to N), (i) determine the coordinate <first time, first voltage> as a first diagnostic position vector and the coordinate <second time, second voltage> as a second diagnostic position vector; (ii) determine the difference between the second diagnostic position vector and the first diagnostic position vector as an i-th diagnostic vector; (iii) determine an i-th diagnostic factor based on the magnitude of the cross product of the diagnostic reference vector and the i-th diagnostic vector; and (f) if the i-th diagnostic factor exceeds a critical value, the i-th battery cell may be diagnosed as having a voltage abnormality.

[0014] In one embodiment, the mean of the first set of voltages may be the arithmetic mean or median of the first set of voltages, and the mean of the second set of voltages may be the arithmetic mean or median of the second set of voltages.

[0015] In another embodiment, the mean of the first voltage set may be the arithmetic mean or median of the voltage values ​​within β sigma of the voltage values ​​included in the first voltage set, and the mean of the second voltage set may be the arithmetic mean or median of the voltage values ​​within β sigma of the voltage values ​​included in the second voltage set, where β may be 1 to 3.

[0016] The control circuit may be configured to set the threshold value based on an average of the i-th diagnostic factor (i is 1 to N).

[0017] The control circuit calculates the average of the i-th diagnostic factor (i is 1 to N) by m ave When m ave ×α (α is 1 to 10) may be set as the critical value.

[0018] In an embodiment of the present invention, the time interval between the first time and the second time may be an integer multiple of the voltage measurement period.

[0019] The battery diagnostic device may further include an interface unit operably coupled to the control circuit to facilitate communication with an external device, and the control circuit may be configured to transmit a diagnosis result of voltage abnormalities for the first through Nth battery cells to the external device through the interface unit.

[0020] The battery diagnostic device may further include an interface unit operably coupled to the control circuit and an output device operably coupled to the interface unit, and the control circuit may be configured to visually or audibly output a diagnosis result of voltage abnormalities for the first to Nth battery cells through the output device.

[0021] In order to achieve the above object, a battery diagnosis method according to another aspect of the present invention includes the steps of: (a) generating first to Nth voltage time series data of a first to Nth battery cells from voltage signals received from a voltage sensing circuit and recording the data on a recording medium; (b) selecting a first voltage set and a second voltage set measured at a first time and a second time after the first time from the first to Nth voltage time series data; (c) determining a coordinate <first time, average of the first voltage set> as a first average position vector and a coordinate <second time, average of the second voltage set> as a second average position vector; and (d) selecting a second average position vector from the first to Nth voltage time series data. (e) for an i-th battery cell (i is 1 to N), (i) determine a coordinate <first time, first voltage> as a first diagnostic position vector and a coordinate <second time, second voltage> as a second diagnostic position vector, (ii) determine a difference between the second diagnostic position vector and the first diagnostic position vector as an i-th diagnostic vector, and (iii) determine an i-th diagnostic factor based on the magnitude of the cross product of the diagnostic reference vector and the i-th diagnostic vector; and (f) if the i-th diagnostic factor exceeds a critical value, diagnose the i-th battery cell as having a voltage abnormality.

[0022] The above object can also be achieved by a battery pack including the above-mentioned battery diagnostic device and a vehicle including the battery pack. [Effects of the Invention]

[0023] According to one aspect of the present invention, a battery cell in which a voltage abnormality has occurred can be easily identified and diagnosed through a simple mathematical operation from among a plurality of battery cells.

[0024] Furthermore, according to one aspect of the present invention, the calculation method used for diagnosing the battery is not complicated, and therefore does not require a high-spec processor.

[0025] In addition, according to one aspect of the present invention, the reliability of voltage abnormality diagnosis can be improved by quantitatively analyzing the difference in voltage change behavior of an abnormal battery cell compared to the average voltage change behavior of the battery cell.

[0026] Furthermore, according to one aspect of the present invention, even if the difference between voltages measured at different times is not large, a battery cell exhibiting abnormal voltage behavior can be reliably identified.

[0027] The effects of the present invention are not limited to those described above, and other effects of the present invention not mentioned above will be clearly understood by those skilled in the art from the description of the claims.

[0028] 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 concept 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]

[0029] [Figure 1] 1 is a diagram illustrating an exemplary configuration of a vehicle according to an embodiment of the present invention; [Figure 2a] 10 is a graph showing nine voltage time series data for a total of nine battery cells in accordance with an embodiment of the present invention. [Figure 2b] In an embodiment of the present invention, a diagnostic criterion vector determined from a voltage set at a first time tk* and a voltage set at a second time tk*+1 is

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[0030] 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 and 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 describe the invention.

[0031] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments 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 therefor at the time of this application.

[0032] Terms including ordinal numbers such as "first," "second," etc. are used to distinguish one of various components from other components, and do not limit the components.

[0033] Throughout the specification, when a part "includes" a certain element, this does not exclude other elements and means that other elements may be included unless otherwise specified. Furthermore, elements such as a "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.

[0034] 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.

[0035] FIG. 1 is a diagram showing an example of the configuration of a vehicle according to an embodiment of the present invention.

[0036] Referring to FIG. 1, an automobile 1 includes a battery pack B, an inverter 3, an electric motor 4, and a vehicle controller 5.

[0037] The automobile 1 refers to a vehicle driven by a motor using electric energy provided by a battery pack B. As an example, the automobile 1 may be an electric vehicle, a plug-in hybrid vehicle, or a hybrid vehicle. The automobile 1 may have two, three, or four wheels.

[0038] The battery pack B includes a cell group CG, a switch 6, and a battery management system 100.

[0039] The cell group CG may be coupled to the inverter 3 through a pair of power supply terminals provided on the battery pack B. The cell group CG includes a first battery cell BC1 to an N-th battery cell BC2 connected in series. N Here, N is a natural number equal to or greater than 2 and indicates the number of battery cells. i The type of battery is not particularly limited as long as it can be repeatedly charged and discharged, such as a lithium-ion battery cell. i is an index for identifying the battery cell. i is a natural number ranging from 1 to N.

[0040] i-th battery cell BC i The battery bank may include a plurality of unit cells connected in parallel. The unit cells may be physically separated batteries. The type of the unit cells is not particularly limited as long as they can be repeatedly charged and discharged, such as lithium-ion battery cells.

[0041] The switch 6 is connected in series with the cell group CG. The switch 6 is provided in a current path for charging and discharging the cell group CG. The switch 6 is controlled to be turned on and off in response to a switching signal from the battery management system 100. The switch 6 may be a mechanical relay 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).

[0042] The inverter 3 is provided to convert DC current from the cell group CG into AC current in response to commands from the battery management system 100 or the vehicle controller 5. The electric motor 4 may be, for example, a three-phase AC motor. The electric motor 4 is driven by AC power provided by the inverter 3.

[0043] The battery management system 100 is provided to handle overall control related to charging and discharging of the cell groups CG during operation of the automobile 1. Here, operation of the automobile 1 may include driving the automobile 1, making temporary stops during driving, parking, charging, etc.

[0044] The battery management system 100 includes a battery diagnostic device 200. The battery management system 100 may further include at least one of a current sensor 310, a temperature sensor 320, and an interface unit 330.

[0045] The battery diagnostic device 200 measures the first battery cell BC1 to the Nth battery cell BC2 while the automobile 1 is running. N The battery diagnostic device 200 includes a voltage sensing circuit 210 and a control circuit 220.

[0046] The voltage sensing circuit 210 senses the voltages of the first battery cell BC1 to the Nth battery cell BC2 through a plurality of voltage sensing lines. NThe voltage sensing circuit 210 is connected to each of the positive and negative electrodes of the battery cell BC at regular time intervals under the control of the control circuit 220 while the automobile 1 is running. i and generating a voltage signal indicative of the measured cell voltage.

[0047] The voltage sensing circuit 210 may include a typical voltage measurement circuit known in the art, such as a multiplexing circuit that can sequentially select battery cells to be measured at time intervals, a filter circuit that removes noise from the voltage measurement signal, and an amplifier circuit that amplifies the voltage measurement signal.

[0048] The current sensor 310 is connected in series to the cell group CG through a current path. The current sensor 310 is configured to detect the battery current flowing through the cell group CG at regular time intervals under the control of the control circuit 220 while the vehicle 1 is in operation, and to generate a current signal indicative of the detected battery current.

[0049] The current sensor 310 may be a conventional sensor known in the art, such as a sense resistor or a Hall sensor. The current flowing through the cell group CG may be a charging current or a discharging current.

[0050] The temperature sensor 320 is configured to detect the temperature of the cell group CG at regular time intervals under the control of the control circuit 220 while the automobile 1 is in operation, and to generate a temperature signal indicative of the detected temperature.

[0051] The temperature sensor 320 may be a conventional sensor known in the art, such as a thermocouple. i The temperature sensors may be provided at multiple points within the battery pack B so that the temperatures of the sensors can be measured independently.

[0052] The control circuitry 220 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.

[0053] The control circuit 220 may have a recording medium 221. The recording medium 221 may be in the form of at least one of a flash memory, a hard disk, a solid state disk (SSD), a solid disk drive (SDD), a multimedia microcard, a random access memory (RAM), a static RAM (SRAM), a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), and a programmable read only memory (PROM).

[0054] The recording medium 221 can record data and programs required for the calculation operations by the control circuit 220. The recording medium 221 can accumulate and record the results of the calculation operations by the control circuit 220, for example, data indicating diagnostic results, together with time stamps.

[0055] The control circuit 220 may be operatively coupled to the voltage sensing circuit 210, the temperature sensor 320, the current sensor 310, the interface unit 330, and / or the switch 6. The control circuit 220 may collect sensing signals from the voltage sensing circuit 210, the current sensor 310, and the temperature sensor 320 at regular time intervals while the automobile 1 is running. The sensing signals include a voltage signal, a current signal, and / or a temperature signal. The voltage signal, the current signal, and / or the temperature signal may be measured in a synchronized manner. The control circuit 220 may collect sensing signals from each battery cell BC at regular time intervals while the automobile 1 is running.i In order to generate time series data relating to the voltage, current, and / or temperature of the battery cell BC, the voltage signal, current signal, and / or temperature signal may be converted into digital data and accumulated and recorded in the recording medium 221 together with a time stamp. i Time series data regarding the voltage of battery pack B, the current flowing through battery pack B, and the temperature can be accumulated and recorded.

[0056] The time series data for voltage may include a number of voltage data corresponding to the number of times the voltage is measured. One voltage data includes the measurement time and the measured voltage value. The time series data for current may include a number of current data corresponding to the number of times the current is measured. One current data includes the measurement time and the measured current value. The time series data for temperature may include a number of temperature data corresponding to the number of times the temperature is measured. One temperature data includes the measurement time and the measured temperature value.

[0057] The control circuit 220 determines the magnitude and sign of the current measured by the current sensor 310, and determines whether the i-th battery cell BC i It can identify whether the battery is charging, discharging, or in an unloaded state.

[0058] Specifically, the control circuit 220 may determine that the battery cell is in an unloaded state when the magnitude of the current measured through the current sensor 310 is zero or a minute current level. Furthermore, the control circuit 220 may determine that the battery cell is discharging when the magnitude of the current measured through the current sensor 310 is greater than zero and the sign of the current value is positive. Furthermore, the control circuit 220 may determine that the battery cell is charging when the magnitude of the current measured through the current sensor 310 is greater than zero and the sign of the current value is negative.

[0059] The interface unit 330 may include a communication circuit configured to support wired or wireless communication between the control circuit 220 and the vehicle controller 5 (e.g., an electronic control unit (ECU)). The wired communication may be, for example, a Controller Area Network (CAN) 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 220 and the vehicle controller 5.

[0060] The interface unit 330 may be operatively coupled to an output device 331 that provides information received from the vehicle controller 5 and / or the control circuit 220 in a form that can be recognized by a user. The output device 331 may include a display 331a and a speaker 331b.

[0061] The interface unit 330 may include a video I / O interface and / or an audio I / O interface to visually or audibly output the diagnosis result through the output device 331 .

[0062] The vehicle controller 5 can control the inverter 3 based on battery information (for example, voltage, current, temperature, SOC (State of Charge)) collected through communication with the battery management system 100.

[0063] The control circuit 220 detects the voltage of the i-th battery cell BC measured by the voltage sensing circuit 210 while the automobile 1 is running. i The time series data for the voltage is recorded on the recording medium 221, and the time series data can be used to diagnose whether or not the battery cell has a voltage abnormality.

[0064] Specifically, the control circuit 220 controls the first battery cell BC1 to the N-th battery cell BC NDuring charging or discharging of the battery cells BC1 to BCN, the voltage sensing circuit 210 periodically receives a voltage signal. N The first to N-th voltage time series data are recorded on the recording medium 221.

[0065] When the number of voltage data included in each of the first to N-th voltage time series data reaches a predetermined number n, the control circuit 220 controls the first to N-th battery cells BC1 to BC2. N Here, n may be in the hundreds to thousands, but the present invention is not limited to this.

[0066] When the diagnosis is started, the control circuit 220 calculates the voltage time series data from the first voltage time series data to the N-th voltage time series data at the first time t k The first voltage measured at Vi,k and the first time t k A second time t later k+1 The second voltage V measured at i,k+1 Select a set of

[0067] First time t k and the second time t k+1 indicates the time at which the voltage was measured. i,k Set the second voltage V i,k+1 The subscript i in the symbol indicating the set is a natural number from 1 to N. Therefore, the first voltage V i,k Set the second voltage V i,k+1 Each set contains a total of N voltage values.

[0068] k is an index for a diagnostic cycle and is a variable for distinguishing each diagnostic cycle when the diagnostic cycle is repeated multiple times. The first to Nth voltage time series data are voltage time series data of the first to Nth battery cells, respectively, and include a total of n voltage values. For example, k may have a value from 1 to n-1 and may increase by 1 from 1 to n-1 as the diagnostic cycle increases. That is, k is 1 in the first diagnostic cycle and may increase sequentially from 2 to n-1 with each increase in the diagnostic cycle. As k changes from 1 to n-1, the number of diagnostic cycles is n-1.

[0069] In the embodiment, at a first time t k and the second time t k+1 The interval between the first time t k and the second time t k+1 The interval between the first voltage V and the Nth voltage time series data may be an integer multiple of the voltage measurement period. i,k Set the second voltage V i,k+1 The number of diagnostic cycles is reduced from n-1 because the time interval at which the set is sampled increases. k and the second time t k+1 When the interval between is m times the voltage measurement period, the number of diagnostic cycles is reduced to n-1 / m. The decimal point can be truncated from the result of the fractional calculation for the diagnostic cycle.

[0070] The control circuit 220 calculates the first voltage V from the first voltage time series data to the N-th voltage time series data. i,k Set the second voltage V i,k+1 Then select the set of coordinates < the first time t k , first voltage V i,k The average V of the set k,ave > is determined as the first mean position vector, and < the second time t k+1 , second voltage V i,k+1 The average V of the set k+1,ave > as the second mean position vector.

[0071] In an embodiment, < the first time t k , first voltage V i,k The average V of the set k,ave > and <2nd time t k+1 , second voltage V i,k+1 The average V of the set k+1,ave > corresponds to two-dimensional vector coordinates.

[0072] Below, <1st time t k , first voltage V i,k The average V of the set k,ave > <t k ,V k,ave > and <2nd time t k+1 , second voltage V i,k+1 The average V of the set k+1,ave > <t k+1 ,V k,ave > is also abbreviated.

[0073] The first average position vector and the second average position vector are respectively

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[0074] In one embodiment, the first voltage V i,k The average V of the set k,ave is the first voltage V i,k Similarly, the second voltage V i,k+1 The average V of the setk+1,ave is the second voltage V i,k+1 may be the arithmetic mean of a set of

[0075] In another embodiment, the first voltage V i,k The average V of the set k,ave is the first voltage V i,k Similarly, the second voltage V i,k+1 The average V of the set k+1,ave is the second voltage V i,k+1 It can be the median of a set of

[0076] In yet another embodiment, the first voltage V i,k The average V of the set k,ave is the first voltage V i,k The voltage value may be the arithmetic mean or median of the voltage values ​​contained in the set of voltages within β sigma.

[0077] Similarly, the second voltage V i,k+1 The average V of the set k+1,ave is the second voltage V i,k+1 It may be the arithmetic mean or median of the voltage values ​​within β sigma of the voltage values ​​included in the set, where β is between 1 and 3 and sigma is the standard deviation of the voltage values ​​included in the voltage set.

[0078] The control circuit 220 calculates a first average position vector

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[0079] Diagnostic Criteria Vector

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[0080] The control circuit 220 determines the diagnostic reference vector

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[0081] Diagnostic Vector

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[0082] The control circuit 220 controls the i-th battery cell BC i In order to diagnose voltage abnormalities, the diagnostic reference vector

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[0083] cross product

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[0084] In Equation 4, i, j, and k are unit vectors in a three-dimensional coordinate system, and can be represented by coordinates <1,0,0>, <0,1,0>, and <0,0,1>.

[0085] Also, the cross product

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[0086] In Equation 5,

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[0087] The i-th diagnostic factor is J i,k When expressed as a function, the i-th diagnostic factor J i,k can be approximately expressed as Equation 6. [Formula 6]

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[0088] Meanwhile, according to vector theory, the magnitude of the cross product of two vectors corresponds to the width of the parallelogram formed by the two vectors. That is, the magnitude of the cross product can be expressed as Equation 7 below. [Formula 7]

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[0089] In Equation 7, θ corresponds to the angle between two vectors. Due to the characteristics of the sine function, the smaller the angle between two vectors, the closer the magnitude of the cross product is to 0. For reference, as θ increases from 0° to 90°, sinθ increases from 0 to 1, and as θ increases from 90° to 180°, sinθ decreases from 1 to 0 again.

[0090] Therefore, the i-th battery cell BC i the i-th diagnostic factor J i,k is the diagnostic criterion vector

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[0091] If the i-th battery cell BC i If does not indicate a voltage abnormality, the i-th diagnostic vector

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[0092] The control circuit 220 determines whether the i-th diagnostic factor J i,k Using the characteristics of the first battery cell BC i That is, the control circuit 220 can diagnose the voltage abnormality of the i-th diagnostic factor J. i,k exceeds the critical value, the i-th battery cell BC i This can be diagnosed as a voltage abnormality.

[0093] The control circuit 220 determines the i-th diagnostic factor J i,k The critical value can be set based on the average of (i is 1 to N).

[0094] In one example, the control circuit 220 may be configured to i,k The average of m ave When we define m aveA value corresponding to ×α may be set as the critical value. Here, the average may be the calculated mean or median value for the diagnostic factors, or the mean or median value for diagnostic factors within β sigma among the diagnostic factors. α may be 1 to 10, preferably 3 to 4. However, the present invention is not limited by the specific numerical value assigned to α.

[0095] Alternatively, the critical value may be a value previously set through repeated experiments (trial and error). That is, a diagnostic factor for a battery cell in which an actual voltage abnormality occurs may be determined through experiments, and the critical value may be set to a value several percent to several tens of percent lower than the diagnostic factor confirmed through the experiments. In this case, the critical value may be previously recorded in the recording medium 221, and the control circuit 220 may refer to the critical value recorded in the recording medium 221.

[0096] The control circuit 220 controls the i-th battery cell BC i If the i-th battery cell BC is diagnosed as having a voltage abnormality, the diagnosis result may be recorded in the recording medium 221. i The diagnosis result may include the time when the voltage abnormality was diagnosed and identification information (such as a serial number) of the battery cell in which the voltage abnormality occurred. If multiple battery cells are diagnosed with a voltage abnormality, the diagnosis result may include the time when the voltage abnormality was diagnosed and identification information of each battery cell in which the voltage abnormality occurred.

[0097] The control circuit 220 may also output the diagnostic results visually or audibly through an output device 331 operatively coupled to the interface section 330 .

[0098] As one example, the control circuit 220 may output the diagnosis result in a graphical user interface through the display 331a. As another example, the control circuit 220 may output the diagnosis result audibly through the speaker 331b. Preferably, the diagnosis result may include a warning message indicating that a detailed inspection of the battery pack B is required. When the diagnosis result is output visually or audibly, only the warning message may be output, excluding the time when the voltage abnormality was diagnosed and the identification information of the battery cell.

[0099] The control circuit 220 can also transmit the diagnostic results to an external device via wired or wireless communication supported by the interface unit 330 .

[0100] As an example, the external device may be the vehicle controller 5. When the vehicle controller 5 receives the diagnosis result, it may output a warning message in a graphical user interface through an integrated display panel mounted on the vehicle 1. In this case, the driver may take the vehicle 1 to a service center for a detailed inspection of the battery pack B. If the detailed inspection identifies a battery cell with an abnormal voltage, the battery cell may be replaced with another battery cell or the battery pack B may be replaced.

[0101] As another example, the external device may be an on-board diagnostic device (not shown) connected via the interface unit 330. The on-board diagnostic device is a device that checks the status of various components included in the automobile 1. When the on-board diagnostic device is connected via the interface unit 330, the control circuit 220 may read out a diagnosis result regarding an abnormal voltage of a battery cell recorded in the recording medium 221 and transmit the diagnosis result to the on-board diagnostic device via the interface unit 330. Then, the operator may recognize the diagnosis result output through the display of the on-board diagnostic device and perform a detailed inspection of battery pack B. Furthermore, if the operator identifies a battery cell in which an abnormal voltage has occurred, the operator may replace the battery cell with another battery cell or replace battery pack B.

[0102] 2a is a graph showing nine voltage time series data for a total of nine battery cells in accordance with an embodiment of the present invention, in which vertical dotted lines indicate multiple voltage measurement points.

[0103] As shown in Figure 2a, out of the nine battery cells, battery cell ID 6 experienced lithium plating on the negative electrode, resulting in abnormal voltage change behavior different from the other battery cells in the time period 49070 seconds to 49080 seconds of the voltage time series data (ID#6) (see dotted circle). In other words, all battery cells except battery cell 6 show a linear voltage increase pattern, but battery cell 6 shows a sudden change in voltage slope in the period 49070 seconds to 49080 seconds. For reference, the voltages of the nine battery cells vary slightly at the same measurement point because the battery cells have different degrees of deterioration.

[0104] After the voltage time series data as shown in FIG. 2a is recorded in the recording medium 221, the battery diagnostic device 200 according to the embodiment of the present invention may diagnose the sixth battery cell as having an abnormal voltage.

[0105] Specifically, in the first diagnostic cycle, the control circuit 220 calculates a first voltage V measured at a first time t1 and a second time t2. i,1 (i is 1 to 9) and the second voltage V i,2 (i is 1 to 9)

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[0106] Similarly, in the second diagnostic cycle, the control circuit 220 calculates the first voltage V measured at the first time t2 and the second time t3. i,2 (i is 1 to 9) and the second voltage V i,3 (i is 1 to 9)

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[0107] Similarly, the control circuit 220 may determine the first time t k and the second time t k+1 The first voltage V measured at i,k (i is 1 to 9) and the second voltage V i,k+1 (i is 1 to 9)

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[0108] Finally, the control circuit 220 performs the first time t n-1 and the second time t n The first voltage V measured at i,n-1 (i is 1 to 9) and the second voltage V i,n (i is 1 to 9)

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[0109] Meanwhile, the sixth battery cell is measured at the first time t k* and the second time t k*+1 In the section between t and t, the voltage suddenly decreases and the voltage change slope switches from positive to negative, showing abnormal voltage change behavior. k* and the second time t k*+1 The diagnostic factor J of the 6th battery cell determined from the voltage set selected in 6,k* is the diagnostic factor of other battery cells, i.e., J 1,k* , J 2,k* , J 3,k* , J 4,k* , J 5,k* , J 7,k* , J 8,k* , J9,k* may have features greater than

[0110] FIG. 2b shows an embodiment of the present invention in which a first time t k* and the second time t k*+1 The diagnostic criterion vector determined from the voltage set

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[0111] As shown, the diagnostic criteria vector

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[0112] Figure 2c shows the first time t when the 6th battery cell shows voltage abnormality. k* and the second time t k*+1 The diagnostic factor J determined from the voltage set 1,k* , J 2,k* , J 3,k* , J 4,k* , J 5,k* , J6,k* , J 7,k* , J 8,k* and J 9,k* Graph showing the above.

[0113] Referring to Figure 2c, the average diagnostic factor J ave is approximately 0.00078 based on the arithmetic mean value. The diagnostic factors of battery cells 1 to 5 and battery cells 7 to 9 do not show a large deviation from the mean, but the diagnostic factor of battery cell 6 is more than three times larger than the mean. Therefore, if the critical value used as the standard for diagnosing voltage abnormalities of battery cells is set to twice the mean of the diagnostic factors, then at the first time t k* and the second time t k*+1 In this case, the control circuit 220 may diagnose that a voltage abnormality has occurred in the sixth battery cell in the period between t k* and the battery cell identification information (ID6 number) may be recorded as the diagnostic result in the recording medium 221. The control circuit 220 may also visually or audibly output the diagnostic result including a warning message through an output device 331 operably coupled to the interface unit 330. The control circuit 220 may also transmit the diagnostic result to an external device through the interface unit 330.

[0114] The control circuit 220 may periodically execute the above-described diagnostic logic regarding the voltage abnormality of the battery cell on all the battery cells included in the battery pack B. Furthermore, when executing the diagnostic logic on all the battery cells, the control circuit 220 may independently execute the diagnostic logic for each battery cell according to a predetermined order.

[0115] The control circuit 220 may also execute the above-mentioned diagnostic logic for voltage abnormalities of the battery cells in real time in conjunction with the measurement of the cell voltages before acquiring time-series data for the preset n battery cell voltages.

[0116] Specifically, the control circuit 220 calculates the first voltage V measured at the first time t1 immediately after the first voltage measurement time (t1) and the second voltage measurement time (t2) have elapsed. i,1 and a second voltage V measured at a second time t2 i,2 Using the set of diagnostic criteria vectors

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[0117] Similarly, immediately after the second voltage measurement time point (t2) and the third voltage measurement time point (t3) have passed, the control circuit 220 calculates the first voltage V measured at the first time point t2. i,2 and a second voltage V measured at a second time t3 i,3 Using the set of diagnostic criteria vectors

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[0118] Similarly, the control circuit 220 may measure the k-th voltage at any k-th time point (t k ) and the k+1th voltage measurement time (t k+1 ) has passed, the first time t k The first voltage V measured at i,k and the second time t k+1 The second voltage V measured at i,k+1 Using the set of diagnostic criteria vectors

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[0119] Finally, the control circuit 220 detects the n-1th voltage measurement point (t n-1 ) and the nth voltage measurement time (t n ) has passed, the first time t n-1 The first voltage V measured at i,n-1 and the second time t n The second voltage V measured at i,n Using the set of diagnostic criteria vectors

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[0120] The battery diagnostic device 200 according to the embodiment of the present invention may be included in the battery management system 100, a control system (not shown) of a load device, or a diagnostic system provided in a maintenance center for the automobile 1 or the battery pack B.

[0121] In the present invention, the control circuit 220 may optionally include a processor, an ASIC (Application-Specific Integrated Circuit), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., known in the art, to execute the various control logics described above.

[0122] Furthermore, when the control logic is embodied as software, the control circuit 220 may be replaced by a processor that executes a set of program modules. In this case, the program modules may be stored in memory and executed by the processor. The memory may be provided inside or outside the processor and may be connected to the processor by various well-known computer components. The memory may also be included in the recording medium 221. Furthermore, the memory is a general term for devices in which information is stored, regardless of the type of device, and does not refer to a specific memory device.

[0123] In addition, various control logics of the control circuit 220 may be combined, and the combined control logic may be created as a computer-readable code system and stored in a computer-readable recording medium. The type of the recording medium is not particularly limited as long as it is accessible by a processor included in a computer. For example, the recording medium may include at least one selected from the group consisting of ROM, RAM, registers, CD-ROM, magnetic tape, hard disk, floppy disk, and optical data storage device. The code system may also be distributed and stored in and executed by computers connected via a network. Functional programs, codes, and code segments for implementing the combined control logic may be easily construed by a programmer skilled in the art to which the present invention pertains.

[0124] A battery diagnostic method using the battery diagnostic device 200 of the present invention will be described in detail below. In one embodiment, the battery diagnostic method may be performed by the battery diagnostic device 200 while the vehicle 1 is in operation. The operation of the vehicle 1 includes driving, stopping while driving, parking, charging, etc. The operation of the control circuit 220 will be described in more detail in various embodiments of the battery diagnostic method.

[0125] 3 is a flow chart illustrating an exemplary battery diagnostic method according to an embodiment of the present invention. The diagnostic method of FIG. 3 may be repeatedly executed by the control circuit 220 for each battery cell included in the battery pack B at predetermined diagnostic intervals.

[0126] Referring to FIG. 3, when the diagnosis starts, the control circuit 220 controls the voltage sensing circuit 210 to sense the voltages of the first battery cell BC1 to the Nth battery cell BC2 in step S10. N The voltage of the battery cell BC is repeatedly measured at a constant time interval Δt, and first to N-th voltage time series data are generated and recorded in the recording medium 221. The ith voltage time series data is the voltage of the ith battery cell BC i This corresponds to the voltage time series data for

[0127] Then, in step S20, the control circuit 220 assigns 1 to the index k for the diagnostic cycle to initialize the index k.

[0128] Next, in step S30, the control circuit 220 calculates the voltage time series data from the first to N-th voltage time series data recorded on the recording medium 221 at the first time t k The first voltage V measured at i,k and the first time t k A second time t later k+1 The second voltage V measured at i,k+1 where i is 1 to N. Therefore, the first voltage V i,k There are N voltage values ​​included in the set of V. Similarly, the second voltage V i,k+1The set of voltage values ​​in k is also N. The value currently assigned to k is 1.

[0129] Next, the control circuit 220 calculates the coordinates <t k ,V k,ave > the first average position vector

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[0130] First voltage V i,k The average V of the set k,ave and the second voltage V i,k+1 The average V of the set k+1,ave Various embodiments of are described above.

[0131] Next, the control circuit 220 calculates a second average position vector

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[0132] Next, in step S60, the control circuit 220 assigns 1 to the cell index i to initialize the cell index.

[0133] Next, the control circuit 220 calculates the coordinates <t k ,V i,k > The first battery cell BC iFirst diagnostic position vector for

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[0134] Then, in step S80, the control circuit 220 calculates a second diagnostic position vector

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[0135] Next, in step S90, the control circuit 220 calculates the diagnostic reference vectors .times. ...

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[0136] Next, in step S100, the control circuit 220 calculates the i-th diagnostic factor J i,k It is determined whether or not the threshold value is exceeded. Various embodiments for setting the threshold value have been described above.

[0137] If the determination in step S100 is "YES", the control circuit 220 records the diagnosis result in the recording medium 221 in step S110. The diagnosis result is recorded as the time t k and identification information of the battery cell, which may be a cell index, which is the ID of the battery cell.

[0138] If the determination in step S100 is "NO", the control circuit 220 determines in step S120 whether the cell index i is equal to the total number N of battery cells.

[0139] If the determination in step S120 is "No," the control circuit 220 increments the cell index i by 1 in step S130, and then returns the process to step S70. Steps S70 to S110 are repeated to diagnose the voltage abnormality of the next battery cell to be diagnosed. Since the cell index i is assigned with 2, the control circuit 220 diagnoses the voltage abnormality of the second battery cell BC2. The repeated execution of steps S70 to S110 is repeated until the determination in step S120 is "Yes." That is, N Steps S70 to S110 may be repeated until the voltage abnormality diagnosis for the power supply is completed.

[0140] If the determination in step S120 is "YES," the control circuit 220 determines in step S140 whether the diagnostic cycle index k is equal to n-1, where n is the number of voltage values ​​included in each of the first through Nth voltage time series data. Since k is currently assigned with 1, the control circuit 220 increments the diagnostic cycle index by 1 in step S150 and then returns the process to step S30 to perform a second diagnostic cycle.

[0141] That is, the control circuit 220 <t2,V 2,ave > the first average position vector

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[0142] Next, the control circuit 220 initializes the cell index by assigning 1 to the cell index i and <t2,V i,2 > The first battery cell BC i First diagnostic position vector for

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[0143] When the second diagnostic cycle is completed, the control circuit 220 further increments the diagnostic cycle index k by 1 and then executes a third diagnostic cycle.

[0144] The control circuit 220 executes the above-described control logic in substantially the same manner from the third diagnostic cycle to the (n-1)th diagnostic cycle, thereby determining whether the first time t k and the first time t k A second time t later k+1 The first voltage V selected by i,k Set the second voltage V i,k+1 Using the set, the first battery cell BC1 to the Nth battery cell BC N It is possible to diagnose voltage abnormalities.

[0145] On the other hand, when the execution of all the diagnostic cycles based on the first to N-th voltage time-series data is completed, the control circuit 220 can refer to the diagnostic results recorded in the recording medium 221 and execute a post-diagnosis process.

[0146] That is, the control circuit 220 may transmit the diagnostic results recorded in the recording medium 221 to an external device via the interface unit 330. The diagnostic results transmitted to the external device may include identification information of the battery cell where the voltage abnormality occurred and information regarding the time point at which the battery cell was diagnosed with the voltage abnormality. The diagnostic results transmitted to the external device may further include a warning message indicating that inspection of battery pack B is required or a corresponding diagnostic code. Alternatively, the identification information of the battery cell where the voltage abnormality occurred and detailed information regarding the time point at which the battery cell was diagnosed with the voltage abnormality may be excluded from the diagnostic results transmitted to the external device. When the external device is the vehicle controller 5, the vehicle controller 5 may output the diagnostic results in a graphical user interface on an integrated display panel mounted on the automobile 1. When the external device is an onboard diagnostic device operably coupled to the interface unit 330, the onboard diagnostic device may output the diagnostic results via a display. In this case, the diagnostic results preferably include a diagnostic code indicating that a battery cell where the voltage abnormality occurred is present in the battery pack.

[0147] As another example, after completing the diagnosis for all the battery cells, the control circuit 220 may visually or audibly output the diagnosis result recorded in the recording medium 221 through the output device 331 operably coupled to the interface unit 330. The diagnosis result output through the output device 331 may include identification information of the battery cell where a voltage abnormality has occurred and information about the time point at which the battery cell was diagnosed with a voltage abnormality. Alternatively, the diagnosis result output through the output device 331 may further include a warning message that inspection of battery pack B is required or a corresponding diagnostic code. As another alternative, the identification information of the battery cell where a voltage abnormality has occurred and detailed information about the time point at which the battery cell was diagnosed with a voltage abnormality may be excluded from the diagnosis result output through the output device 331.

[0148] If the diagnosis result is output through the output device 331, the user of the automobile 1 can take the automobile 1 to a service center to more precisely diagnose the condition of the battery pack B. If a phenomenon such as lithium plating is actually confirmed in some battery cells included in the battery pack B, the battery pack B may be replaced.

[0149] Meanwhile, the battery diagnostic method according to the present invention may be modified as follows: The control circuit 220 may execute a diagnostic cycle in real time in conjunction with measuring the cell voltages before acquiring time-series data for the preset n cell voltages.

[0150] Specifically, the control circuit 220 calculates the first time t corresponding to the k-th measurement time point. k and the second time t corresponding to the k+1 measurement point k+1 Immediately after the first time t k The first voltage V measured at i,k and the second time t k+1 The second voltage V measured at i,k+1 Using the set of diagnostic criteria vectors

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[0151] The control circuit 220 controls the first battery cell BC1 to the Nth battery cell BC N Each time a voltage measurement is made for k, k may be incremented by 1 from 1 to n-1, and the real-time control logic described above may be repeated for each increment of k.

[0152] The real-time diagnostic logic of the control circuit 220 may be executed in synchronization with the cell voltage measurement process of each battery cell. Furthermore, when the diagnosis of all battery cells is completed, the control circuit 220 may transmit the diagnostic result to an external device through the interface unit 330 as described above, or may output the diagnostic result visually or audibly through the output device 331 operably coupled to the interface unit 330.

[0153] According to the above-described embodiment, a battery cell in which a voltage abnormality has occurred can be easily identified and diagnosed through a simple mathematical operation from among a plurality of battery cells.

[0154] Additionally, embodiments of the present invention do not require a high-spec processor because the calculations used to diagnose the battery are not complex.

[0155] Furthermore, according to an embodiment of the present invention, the reliability of voltage abnormality diagnosis can be improved by quantitatively analyzing the difference between the average voltage change behavior of a battery cell and the abnormal voltage change behavior of a battery cell in which a voltage abnormality has occurred.

[0156] Furthermore, embodiments of the present invention may reliably identify battery cells that exhibit abnormal voltage behavior even if the difference between voltages measured at different times is not large.

[0157] In various embodiments of the present invention, components referred to as "modules" or "circuits" should be understood as functionally divided elements, not physically divided elements. Therefore, each component may be selectively integrated with other components, or each component may be divided into subcomponents for efficient execution of control logic. However, it will be obvious to those skilled in the art that, even if components are integrated or divided, as long as the same function can be recognized, the integrated or divided components are also construed as being within the scope of the present invention.

[0158] 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.

[0159] Furthermore, the present invention described above is not limited to the above-described embodiments and drawings, and various substitutions, modifications, and alterations can be made by a person having ordinary knowledge in the technical field to which the present invention belongs without departing from the technical concept of the present invention. It is also possible to selectively combine all or part of each embodiment for various modifications.

Claims

1. a voltage sensing circuit configured to generate a voltage signal for each of the first battery cell to the Nth battery cell; a recording medium configured to record voltage time series data; a control circuit operatively coupled to the voltage sensing circuit and the recording medium; The control circuit (a) receiving a voltage signal from the voltage sensing circuit and recording first to Nth voltage time series data of the first to Nth battery cells on the recording medium; (b) selecting a first set of voltages measured at a first time and a second set of voltages measured at a second time after the first time from the first voltage time series data through the Nth voltage time series data; (c) determining the coordinate <first time, average of first voltage set> as a first average position vector and the coordinate <second time, average of second voltage set> as a second average position vector; (d) determining the difference between the second average position vector and the first average position vector as a diagnostic criterion vector; (e) for an i-th battery cell (i is 1 to N), (i) determine the coordinate <first time, first voltage> as a first diagnostic position vector and the coordinate <second time, second voltage> as a second diagnostic position vector; (ii) determine the difference between the second diagnostic position vector and the first diagnostic position vector as an i-th diagnostic vector; and (iii) determine an i-th diagnostic factor based on the magnitude of the cross product of the diagnostic reference vector and the i-th diagnostic vector; (f) a battery diagnostic device configured to diagnose the i-th battery cell as having a voltage abnormality if the i-th diagnostic factor exceeds a critical value;

2. the average of the first set of voltages is the arithmetic mean or median of the first set of voltages; The battery diagnostic device of claim 1 , wherein the average of the second set of voltages is an arithmetic mean or median of the second set of voltages.

3. the average of the first voltage set is an arithmetic mean or median of voltage values ​​included in the first voltage set that are within β (β is 1 to 3) sigma; 2. The battery diagnostic device of claim 1, wherein the average of the second voltage set is an arithmetic mean or median of voltage values ​​included in the second voltage set that are within β (β is 1 to 3) sigma.

4. The control circuit The average of the i diagnostic factors (i is 1 to N) is m ａｖｅ When m ａｖｅ 2. The battery diagnostic device of claim 1, wherein the critical value is set to a value corresponding to ×α (α is 1 to 10).

5. 2. The battery diagnostic device according to claim 1, wherein the time interval between the first time and the second time is an integer multiple of a voltage measurement period.

6. an interface unit operatively coupled to the control circuit to facilitate communication with an external device; 2. The battery diagnostic device according to claim 1, wherein the control circuit is configured to transmit a diagnosis result of voltage abnormality for the first to N-th battery cells to an external device through the interface unit.

7. an interface unit operably coupled to the control circuit; an output device operably coupled to the interface portion; 2. The battery diagnostic device of claim 1, wherein the control circuit is configured to visually or audibly output the diagnosis result of the voltage abnormality for the first battery cell to the Nth battery cell through the output device.

8. A battery pack comprising the battery diagnostic device according to any one of claims 1 to 7.

9. A motor vehicle comprising the battery pack of claim 8.

10. (a) generating first to Nth voltage time series data of a first to Nth battery cells from voltage signals received from a voltage sensing circuit and recording the data on a recording medium; (b) selecting a first set of voltages and a second set of voltages measured at a first time and a second time after the first time from the first voltage time-series data to the Nth voltage time-series data; (c) determining the coordinate <first time, average of first voltage set> as a first average position vector and the coordinate <second time, average of second voltage set> as a second average position vector; (d) determining the difference between the second average position vector and the first average position vector as a diagnostic criterion vector; (e) for an ith battery cell (i is 1 to N), (i) determine the coordinate <first time, first voltage> as a first diagnostic position vector and the coordinate <second time, second voltage> as a second diagnostic position vector; (ii) determine the difference between the second diagnostic position vector and the first diagnostic position vector as an ith diagnostic vector; and (iii) determine an ith diagnostic factor based on the magnitude of the cross product of the diagnostic reference vector and the ith diagnostic vector. (f) diagnosing the i-th battery cell as having a voltage abnormality if the i-th diagnostic factor exceeds a critical value.

11. The step (c) setting the arithmetic mean or median of the first set of voltages to the mean of the first set of voltages; and setting the arithmetic mean or median of the second set of voltages to the mean of the second set of voltages.

12. The step (c) setting the arithmetic mean or median of first voltages within β (β is between 1 and 3) sigma to the mean of the first set of voltages; and setting the average of the set of second voltages to an arithmetic mean or median value of the second voltages within β (β is 1 to 3) sigma.

13. In the step (f), the average of the i diagnostic factors (i is 1 to N) is m ａｖｅ When m ａｖｅ 12. The battery diagnosis method of claim 11, wherein the critical value is set to a value corresponding to ×α (α is 1 to 10).

14. 14. The battery diagnostic method according to claim 10, wherein the time interval between the first time and the second time is an integer multiple of a voltage measurement period.

15. transmitting a diagnosis result of the voltage abnormality for the first to Nth battery cells to an external device through an interface unit; or 14. The battery diagnosis method of claim 10, further comprising visually or audibly outputting a diagnosis result of voltage abnormality for the first to N-th battery cells through an output device.

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