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

Abstract

A battery diagnostic device according to an embodiment of the present invention includes a voltage sensing circuit configured to generate a voltage signal indicating a cell voltage of a battery cell, a recording medium configured to record time-series data of the cell voltages, and a control circuit operatively coupled to the voltage sensing circuit and the recording medium. The control circuit is configured to (i) receive the voltage signal and record the time-series data of the cell voltages on the recording medium, (ii) select a set of cell voltages measured at k-th, k+1-th, and k+2-th cell voltages from the time-series data as diagnostic data (where k is an index indicating the order of cell voltage measurements, is a natural number greater than or equal to 1, and is assigned multiple values), (iii) determine a first voltage difference between the k-th cell voltage and the k+1-th cell voltage, and a second voltage difference between the k+1-th cell voltage and the k+2-th cell voltage, and (iv) diagnose a battery cell as having an abnormal voltage if a count of a cell voltage set for which a normal diagnosis condition, that is, the pth power of the first voltage difference (p is a natural number greater than or equal to 1) is greater than the pth power of the second voltage difference, is equal to or greater than a reference 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. 10-2022-0117336, filed on September 16, 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) of the battery cell, it is difficult to accurately diagnose a voltage abnormality of a battery cell 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-mentioned problems, and aims to provide a battery diagnostic device, a battery diagnostic method, a battery pack, and a vehicle for efficiently and accurately diagnosing voltage abnormalities in battery cells using the tendency of the slope of voltage changes in the battery cells.

[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] In order 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 a voltage signal indicative of a cell voltage of a battery cell, a recording medium configured to record time-series data of the cell voltage, and a control circuit operably coupled to the voltage sensing circuit and the recording medium.

[0013] The control circuit may be configured to (i) receive the voltage signal and record time series data of the cell voltages on a recording medium, (ii) select as diagnostic data sets the kth, k+1th, and k+2th cell voltages measured from the time series data (k is an index indicating the measurement order of the cell voltages, is a natural number greater than or equal to 1, and is assigned multiple values), (iii) determine a first voltage difference between the kth cell voltage and the k+1th cell voltage, and a second voltage difference between the k+1th cell voltage and the k+2th cell voltage, and (iv) diagnose the battery cell as having a voltage abnormality if the count number of cell voltage sets for which the normal diagnostic condition that the pth power of the first voltage difference (p is a natural number greater than or equal to 1) is greater than the pth power of the second voltage difference is not met among the multiple cell voltage sets is equal to or greater than a reference value.

[0014] The p may be a natural number of 1 or 2 or more.

[0015] The reference value may be a natural number of 1 or 2 or more.

[0016] The control circuit may be configured to select a plurality of the cell voltage sets from the time-series data of the cell voltages while increasing k by 1 from 1 to n-2 (n is the number of voltage data included in the time-series data).

[0017] The control circuit may be configured to perform the control logics (i) to (iv) when the operating state of the battery cell is switched from a charging or discharging state to an unloaded state.

[0018] The diagnostic apparatus may further include an interface portion operatively coupled to the control circuitry to facilitate communication with an external device.

[0019] The control circuit may be configured to transmit a diagnosis result to an external device through the interface unit when the battery cell is diagnosed with an abnormal voltage.

[0020] The diagnostic apparatus may further include an interface portion operably coupled to the control circuitry, and an output device operably coupled to the interface portion.

[0021] The control circuit may be configured to output a diagnosis result visually or audibly through the output device when the battery cell is diagnosed with a voltage abnormality.

[0022] The above object is also achieved by a battery pack including the above-described battery diagnostic device and a vehicle including the battery pack.

[0023] In order to achieve the above object, another aspect of the present invention provides a battery diagnostic method including: (a) receiving a voltage signal indicating a cell voltage of a battery cell from a voltage sensing circuit and recording time-series data of the cell voltages on a recording medium; (b) selecting a set of cell voltages measured at kth, k+1th, and k+2nd cell voltages from the time-series data as diagnostic data (where k is an index indicating the order of cell voltage measurement, is a natural number greater than or equal to 1, and is assigned multiple values); (c) determining a first voltage difference between the kth cell voltage and the k+1th cell voltage, and a second voltage difference between the k+1th cell voltage and the k+2th cell voltage; and (d) diagnosing a battery cell as having an abnormal voltage if the count of a cell voltage set for which a normal diagnostic condition, that is, the pth power of the first voltage difference (p is a natural number greater than or equal to 1) is greater than the pth power of the second voltage difference, is equal to or greater than a reference value, for the plurality of cell voltage sets.

[0024] The p may be a natural number of 1 or 2 or more.

[0025] The reference value may be a natural number of 1 or 2 or more.

[0026] The plurality of cell voltage sets may be selected from the time-series data of cell voltages by increasing k by 1 from 1 to n-2 (n is the number of cell voltages included in the time-series data).

[0027] The steps (a) to (d) may be performed when the operating state of the battery cell is switched from a charging or discharging state to an unloaded state.

[0028] The diagnostic method may further include transmitting a diagnosis result to an external device if the battery cell is diagnosed as having a voltage abnormality.

[0029] The diagnostic method may further include outputting a diagnosis result visually or audibly through an output device when the battery cell is diagnosed as having a voltage abnormality. [Effects of the Invention]

[0030] According to one aspect of the present invention, a battery cell in which a voltage abnormality has occurred can be easily diagnosed by analyzing the tendency of the cell voltage slope between consecutively measured cell voltages using a simple mathematical operation.

[0031] 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.

[0032] Furthermore, according to one aspect of the present invention, the reliability of voltage abnormality diagnosis can be improved by using a mathematical operation that can amplify the tendency of the cell voltage gradient.

[0033] 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.

[0034] The effects of the present invention are not limited to the effects 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.

[0035] 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]

[0036] [Figure 1] 1 is a diagram illustrating an exemplary configuration of a vehicle according to an embodiment of the present invention; [Figure 2a] FIG. 10 is a graph showing a portion of a cell voltage profile exhibited by a normal battery cell when the battery cell being charged is switched to an unloaded state in an embodiment of the present invention, and is used to derive a mathematical formula used to diagnose a voltage abnormality. [Figure 2b] FIG. 10 is a graph showing a portion of a cell voltage profile exhibited by a normal battery cell when a discharging battery cell is switched to an unloaded state in an embodiment of the present invention, the graph being used to derive a mathematical formula used to diagnose a voltage abnormality. [Figure 3a] 4 is a graph showing an example of time-series data of cell voltages of battery cells with normal voltages in an embodiment of the present invention; [Figure 3b] 4 is a graph showing an example of time-series data of a cell voltage of a battery cell in which a voltage abnormality has occurred in an embodiment of the present invention. [Figure 4a] 10 is a graph showing an example of time-series data of cell voltages of battery cells having normal voltages in accordance with another embodiment of the present invention; [Figure 4b] 10 is a graph showing an example of time-series data on the cell voltage of a battery cell in which a voltage abnormality has occurred in another embodiment of the present invention. [Figure 5] 1 is a flow chart illustrating an exemplary battery diagnostic method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Throughout the specification, when a part "includes" a certain element, this does not exclude other elements and means that it may further include other elements unless otherwise specified. Furthermore, terms such as "controller" 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.

[0041] 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.

[0042] FIG. 1 is a diagram showing an example of the configuration of a vehicle according to an embodiment of the present invention.

[0043] Referring to FIG. 1, an automobile 1 includes a battery pack B, an inverter 3, an electric motor 4, and a vehicle controller 5.

[0044] The automobile 1 refers to a vehicle that is driven by a motor using electric energy provided by a battery pack B. As an example, the automobile 1 may be an electric automobile, a plug-in hybrid automobile, or a hybrid automobile.

[0045] The battery pack B includes a cell group CG, a switch 6, and a battery management system 100.

[0046] The cell group CG can be coupled to the inverter 3 through a pair of power supply terminals provided on the battery pack B. The cell group CG is made up of a plurality of battery cells BC1 to BC N Here, N is a natural number equal to or greater than 2 and is the number of battery cells. Each battery cell BC 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.

[0047] 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).

[0048] 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.

[0049] The battery management system 100 is provided to take charge of overall control related to charging and discharging of the cell group CG during operation of the automobile 1. Here, operation of the automobile 1 may include driving the automobile 1, stopping while moving, parking, etc.

[0050] 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.

[0051] The battery diagnostic device 200 measures the temperature of the battery cells BC1 to BC2 while the automobile 1 is running. N The battery diagnostic device 200 includes a voltage sensing circuit 210 and a control circuit 220, which are provided to diagnose individual voltage abnormalities.

[0052] The voltage sensing circuit 210 senses the voltages of the plurality of battery cells BC1 to BC2 through a plurality of voltage sensing lines. N The voltage sensing circuit 210 is connected to each positive and negative electrode 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. The voltage sensing circuit 210 may include a typical voltage measurement circuit known in the art. The voltage measurement circuit may include 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, an amplifier circuit that amplifies the voltage measurement signal, and the like.

[0053] 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 running, and generate a current signal indicative of the detected battery current. 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.

[0054] 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 running, and generate a temperature signal indicative of the detected temperature. The temperature sensor 320 may be a conventional sensor known in the art, such as a thermocouple. The temperature sensor 320 detects the temperature of each battery cell BC at regular time intervals under the control of the control circuit 220. 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.

[0055] 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.

[0056] The control circuit 220 may include 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). The recording medium 221 may record data and programs required for the calculations performed by the control circuit 220. The recording medium 221 may cumulatively record the results of the calculations performed by the control circuit 220, such as data indicating diagnostic results, together with a timestamp.

[0057] 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 voltage signals, current signals, and / or temperature signals. The voltage signals, current signals, and / or temperature signals may be collected in a synchronized measurement manner. The control circuit 220 may convert the voltage signals, current signals, and / or temperature signals into digital data and accumulate and record them in the recording medium 221 to generate time-series data regarding the voltage, current, and / or temperature of the battery cells. Thus, the recording medium 221 may store the voltage, current, and / or temperature signals of each battery cell BC. i Time series data regarding the cell voltage, the current flowing through battery pack B, and the temperature may be accumulated and recorded.

[0058] The time series data for voltage may include a number of voltage data corresponding to the number of voltage measurements. One voltage data includes a measurement time point and a measured voltage value. The time series data for current may include a number of current data corresponding to the number of current measurements. One current data includes a measurement time point and a measured current value. The time series data for temperature may include a number of temperature data corresponding to the number of temperature measurements. One temperature data includes a measurement time point and a measured temperature value.

[0059] The control circuit 220 can identify whether the battery cell is being charged, discharged, or in an unloaded state by referring to the magnitude and sign of the current measured through the current sensor 310.

[0060] Specifically, the control circuit 220 may identify the battery cell as being in an unloaded state when the magnitude of the current measured through the current sensor 310 is 0. Furthermore, the control circuit 220 may identify the battery cell as being discharging when the magnitude of the current measured through the current sensor 310 is greater than 0 and the sign of the current value is positive. Furthermore, the control circuit 220 may identify the battery cell as being charging when the magnitude of the current measured through the current sensor 310 is greater than 0 and the sign of the current value is negative.

[0061] 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.

[0062] 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.

[0063] The interface unit 330 may include a video I / O interface and an audio I / O interface to output the diagnosis result visually or audibly through the output device 331 .

[0064] 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.

[0065] The control circuit 220 detects the voltage of each battery cell BC measured by the voltage sensing circuit 210 while the automobile 1 is running. i The time series data for the cell 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.

[0066] Specifically, the control circuit 220 selects, as diagnostic data, a set of cell voltages measured at the kth, k+1th, and k+2nd times from the time-series data of cell voltages recorded on the recording medium 221. Here, k is an index indicating the order in which the cell voltages are measured, and is a natural number between 1 and n. n is the total number of cell voltages included in the time-series data. For convenience of explanation, the voltage value measured at the kth time will be referred to as V k I decided to write it as follows.

[0067] When k is 1, the control circuit 220 selects a set of cell voltages V1, V2, and V3 from the time-series data of the cell voltages. When k is 2, the control circuit 220 selects a set of cell voltages V2, V3, and V4 from the time-series data of the cell voltages. When k is an arbitrary m, the control circuit 220 selects a set of cell voltages V m , V m+1 and Vm+2 m is a natural number between 3 and n-2.

[0068] The control circuit 220 also determines a first voltage difference between the kth cell voltage and the k+1th cell voltage, and a second voltage difference between the k+1th cell voltage and the k+2th cell voltage.

[0069] The control circuit 220 determines whether the normal diagnosis condition, that is, the pth power (p is a natural number greater than or equal to 1) of the first voltage difference is greater than the pth power of the second voltage difference, is met for each cell voltage set selected from the time series data of the cell voltages, and counts the number of cell voltage sets selected from the time series data that do not satisfy the normal diagnosis condition.

[0070] If the number of cell voltage sets that do not satisfy the normal diagnosis condition is equal to or greater than a reference value, the control circuit 220 diagnoses the corresponding battery cell as having an abnormal voltage.

[0071] The reference value can be set to a natural number equal to or greater than 1. In applications requiring a high level of diagnostic sensitivity, the reference value can be set low, for example, between 1 and 3. On the other hand, in applications requiring a normal level of diagnostic sensitivity, the reference value can be set to, for example, 4 or greater.

[0072] Preferably, in the application to which the present invention is applied, the appropriate level of the reference value can be determined through trial and error.

[0073] In one embodiment, the reference value may be increased in applications where voltage noise is likely to flow into the voltage sensing circuit 210. If voltage noise reduces the accuracy of cell voltage measurement, a small reference value may result in a false diagnosis of voltage abnormality even for battery cells that exhibit normal voltage behavior.

[0074] Alternatively, the reference value may be reduced if the voltage sensing circuit 210 is designed to have robustness against voltage noise.

[0075] The above-described diagnostic logic of the control circuit 220 is preferably executed after the battery cells are switched from a charging or discharging state to an unloaded state. The unloaded state refers to a state in which the magnitude of the charging current or discharging current is substantially zero. The unloaded state may also include a state in which the magnitude of the charging current or discharging current is very small. The diagnostic logic of the control circuit 220 may also be executed when the battery cells are being charged or discharged.

[0076] 2a and 2b are diagrams for deriving a mathematical expression indicating a normal diagnosis condition for a battery cell using the voltage behavior of a battery cell without a voltage abnormality.

[0077] The voltage profile shown in FIG. 2a corresponds to a portion of the cell voltage profile exhibited by a normal battery cell without voltage abnormality when the battery cell being charged is switched to an unloaded state in an embodiment of the present invention.

[0078] The voltage profile shown in FIG. 2b corresponds to a portion of the cell voltage profile exhibited by a normal battery cell without voltage abnormality when the discharging battery cell is switched to an unloaded state in an embodiment of the present invention.

[0079] As shown in Figures 2a and 2b, when a battery cell without voltage abnormality is put into an unloaded state during charging or discharging, the polarization of the electrodes is relaxed and the cell voltage drops to the stabilized voltage (V OCV ) tends to gradually converge to the regulated voltage (V OCV ) and converges to the regulated voltage (V OCV ) gradually increases and converges to the stabilization voltage (V OCV ) refers to the open circuit voltage corresponding to the current state of charge of the battery cell. Also, in the initial stage of no-load state, the IR voltage of the battery cell becomes 0, so the range of change in cell voltage is relatively large.

[0080] 2a and 2b, an arbitrary cell voltage set V selected from the time series data of the cell voltage for the battery cell in the unloaded state is k , V k+1 , V k+2 can be represented by three points O1, O2, and O3 on the cell voltage profile.

[0081] Continuously measured cell voltage V k , V k+1 , V k+2 The measurement time points are t k , t k+1 , t k+2 The cell voltage measurement period is constant at Δt, and can be from several milliseconds to several seconds.

[0082] When a battery cell in an unloaded state exhibits normal voltage behavior as shown in the cell voltage profiles of Figures 2a and 2b, for any set of cell voltages, the slope of the line segment L1 connecting two points O1 and O2 is relatively larger than the slope of the line segment L2 connecting two points O2 and O3.

[0083] The cell voltage profile of a battery cell without voltage abnormalities is the regulated voltage (V OCV ) while gradually increasing or decreasing the stabilization voltage (V OCV ) This characteristic can be expressed by the following Equation 1.

[0084] [Formula 1] |(V k+1 -V k )| / |Δt| > | (V k+2 -V k+1 )| / |Δt|

[0085] Furthermore, by multiplying the equations on the right and left sides of Equation 1 by |Δt|, Equation 1 can be expressed as Equation 2.

[0086] [Formula 2] |(V k+1 -V k )| > |(Vk+2 -V k+1 )|

[0087] In Equation 2, |(V k+1 -V k )| is the kth measured cell voltage V k and the k+1th measured cell voltage V k+1 The first voltage difference ΔV corresponds to the absolute difference between 1,k It can be defined as:

[0088] Similarly, |(V k+2 -V k+1 )| is the k+1th measured cell voltage V k+1 and the k+2th measured cell voltage V k+2 The second voltage difference ΔV corresponds to the absolute difference between 2,k It can be defined as:

[0089] According to the definitions of the first voltage difference and the second voltage difference, Equation 2 can be expressed as Equation 3 below.

[0090] [Formula 3] ΔV 1,k > ΔV 2,k

[0091] The inequality of Equation 3 can still be established even if the first voltage difference and the second voltage difference are each raised to the pth power as shown in Equation 4 below.

[0092] [Formula 4] ΔV 1,k p > ΔV 2,k p (where p is a natural number greater than or equal to 1)

[0093] Equation 4 is a set of arbitrary cell voltages V selected from the cell voltage profile for the battery cells. k , V k+1 , V k+2 When diagnosing whether the voltage of the battery cell is abnormal using the voltage detection circuit, the voltage detection circuit can be used as a normal diagnosis condition.

[0094] In Equation 4, p is a natural number equal to or greater than 1. Preferably, p may be equal to or greater than 2. When p is equal to or greater than 2, if the first voltage difference and / or the second voltage difference has a value greater than 1, the value may be amplified more significantly. Also, when p is equal to or greater than 2, if the first voltage difference and / or the second voltage difference has a value less than 1, the value may be attenuated more significantly. Therefore, when p is equal to or greater than 2, the possibility of an error occurring in the process of determining whether the inequality in Equation 4 is satisfied can be reduced. Values ​​greater than 1 are amplified more significantly, and values ​​less than 1 are attenuated more significantly, resulting in the first voltage difference (ΔV 1,k ) and the second voltage difference (ΔV 2,k ) becomes larger.

[0095] When the time-series data includes a total of n cell voltages, the total number of cell voltage sets that can be selected from the time-series data is n-2. Therefore, the control circuit 220 determines whether the normal diagnosis condition of Equation 4 is satisfied for the total of n-2 cell voltage sets, and accumulates and counts the number of cell voltage sets that do not satisfy the normal diagnosis condition.

[0096] The control circuit 220 may also record the count result of the cell voltage sets that do not satisfy the normal diagnosis conditions in the recording medium 221. Furthermore, if the number of cell voltage sets that do not satisfy the normal diagnosis conditions is equal to or greater than a reference value, the control circuit 220 may diagnose the corresponding battery cell as having a voltage abnormality and record the diagnosis result in the recording medium 221. The diagnosis result may include the time when the battery cell was diagnosed as having a voltage abnormality and identification information (such as a serial number) of the 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 diagnostic result in a graphical user interface through the display 331a. As another example, the control circuit 220 may output the diagnostic result audibly through the speaker 331b. Preferably, the diagnostic result may include a warning message indicating that a detailed inspection of the battery pack B is required. When the diagnostic result is output visually or audibly, only the warning message may be output.

[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 a battery cell with an abnormal voltage is identified through the detailed inspection, the battery cell may be replaced with another battery cell.

[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 parts 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, an operator may recognize the diagnosis result output through the display of the on-board diagnostic device and perform a detailed inspection of the battery pack B. Furthermore, if the operator finds that a battery cell has an abnormal voltage, he or she may replace the battery cell with another battery cell.

[0102] The on-board diagnostic device may execute the diagnostic logic of the control circuit 220 described above. In this case, the on-board diagnostic device may receive from the control circuit 220 time-series data of the cell voltage for each battery cell recorded in the recording medium 221. The time-series data of the cell voltage may be measured after the battery pack B is switched from a charging state or a discharging state to a no-load state. The on-board diagnostic device may generate a result of the voltage abnormality diagnosis for each battery cell and output it on a display.

[0103] FIG. 3a is a graph showing an example of time series data for the cell voltage of a battery cell with a normal voltage in an embodiment of the present invention.

[0104] FIG. 3b is a graph showing an example of time-series data on the cell voltage of a battery cell in which a voltage abnormality has occurred in an embodiment of the present invention.

[0105] The cell voltage profiles of Figures 3a and 3b may appear when a battery cell is switched from a charging state to an unloaded state. Alternatively, the cell voltage profiles of Figures 3a and 3b may appear during the discharge of a battery cell.

[0106] Referring to FIG. 3a, the cell voltage of a battery cell with a normal voltage gradually decreases over time without exhibiting any peculiar behavior. Therefore, from the time series data of the cell voltage, an arbitrary cell voltage set V k , V k+1 , V k+2 Even if the cell voltage set is selected, the cell voltage set satisfies the normal diagnosis condition of Equation 4. Therefore, when the time-series data of the cell voltages shows a profile as shown in FIG. 3a, the count number of the cell voltage set that does not satisfy the normal diagnosis condition may be 0.

[0107] Referring to Figure 3b, a battery cell with a voltage abnormality exhibits peculiar behavior (see C1) in a specific time period. For example, if the battery cell is a lithium-ion battery and lithium plating occurs at the negative electrode, the slope of the cell voltage will exhibit peculiar behavior. That is, a section where the slope of the cell voltage increases after gradually decreasing appears. Therefore, in the time period where an abnormal change pattern of the cell voltage appears, the cell voltage set V k , V k+1 , V k+2 is selected, the corresponding cell voltage set does not satisfy the normal diagnosis condition of Equation 4. Therefore, when the time-series data of cell voltages shows a profile as shown in FIG. 3b, the count number of the cell voltage set that does not satisfy the normal diagnosis condition may be 1. Of course, if abnormal cell voltage change patterns appear in multiple locations in the cell voltage profile, the count number of the cell voltage set that does not satisfy the normal diagnosis condition may increase by the number corresponding to the multiple locations.

[0108] FIG. 4a is a graph showing an example of time series data for the cell voltage of a battery cell with a normal voltage in another embodiment of the present invention.

[0109] FIG. 4b is a graph showing an example of time-series data on the cell voltage of a battery cell in which a voltage abnormality has occurred in another embodiment of the present invention.

[0110] The cell voltage profiles of Figures 4a and 4b may appear when a battery cell is switched from a discharged state to an unloaded state. Alternatively, the cell voltage profiles of Figures 4a and 4b may appear during charging of the battery cell.

[0111] Referring to FIG. 4a, the cell voltage of a battery cell with a normal voltage gradually increases over time without exhibiting any peculiar behavior. Therefore, any cell voltage set V k , V k+1 , V k+2Even if the cell voltage set is selected, the cell voltage set satisfies the normal diagnosis condition of Equation 4. Therefore, when the time-series data of the cell voltages shows a profile as shown in FIG. 4a, the count number of the cell voltage set that does not satisfy the normal diagnosis condition may be 0.

[0112] Referring to Figure 4b, a battery cell with a voltage abnormality exhibits peculiar behavior (see C2) in a specific time period. For example, when the battery cell is a lithium-ion battery, if lithium plating occurs on the negative electrode or if an electrode tab breaks, the slope of the cell voltage exhibits peculiar behavior. In other words, a section where the slope of the cell voltage increases appears in the middle of a gradual decrease. Therefore, in the time period when an abnormal change pattern of the cell voltage appears, the cell voltage set V k , V k+1 , V k+2 is selected, the corresponding cell voltage set does not satisfy the normal diagnosis condition of Equation 4. Therefore, when the time-series data of cell voltages shows a profile as shown in FIG. 4b, the count number of cell voltage sets that do not satisfy the normal diagnosis condition may be 1. Of course, if abnormal cell voltage change patterns appear in multiple locations in the cell voltage profile, the count number of cell voltage sets that do not satisfy the normal diagnosis condition may increase by the number corresponding to the multiple locations.

[0113] 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.

[0114] The control circuit 220 may also execute the above-described 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 cell voltages.

[0115] Specifically, when the control circuit 220 starts diagnosing the voltage abnormality of the battery cells, it may determine whether the normal diagnosis condition of Equation 4 is satisfied for the cell voltage set V1, V2, and V3 when the first, second, and third cell voltages V1, V2, and V3 are measured. The cell voltage measurement period is equal to Δt. Also, when the fourth cell voltage V4 is measured, it may determine whether the normal diagnosis condition of Equation 4 is satisfied for the cell voltage set V2, V3, and V4. This process may be repeated every time a cell voltage is measured. That is, when the k+2th cell voltage V k+2 When measured, the cell voltage set V k , V k+1 , V k+2 It may be determined whether the normal diagnosis condition of Equation 4 is satisfied for Vn. This diagnosis process may be repeated until the last cell voltage Vn is measured. The total number of cell voltages to be measured may be preset.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] A battery diagnostic method using the above-described battery diagnostic device 200 of the present invention will now be described in detail. In one embodiment, the battery diagnostic method may be performed by the battery diagnostic device 200 while the vehicle 1 is in operation. In another embodiment, the battery diagnostic method may be performed by the battery diagnostic device 200 while the vehicle 1 is being charged at a charging station. In yet another embodiment, the battery diagnostic device 200 may be included in a charging station, and the battery diagnostic method may be performed by the battery diagnostic device 200 included in the charging station while the vehicle 1 is being charged at the charging station. The battery diagnostic device 200 included in the charging station may receive time-series data of cell voltages for the battery cells from the control circuit 220.

[0121] The operation of the control circuit 220 will be described in more detail in various embodiments of the battery diagnostic method.

[0122] 5 is a flow chart illustrating an exemplary battery diagnostic method according to an embodiment of the present invention. The diagnostic method of FIG. 5 may be repeatedly executed by the control circuit 220 for each battery cell included in the battery pack B at predetermined diagnostic intervals.

[0123] Referring to FIG. 5, when the diagnosis starts, in step S10, the control circuit 220 controls the voltage sensing circuit 210 to repeatedly measure the voltage of the battery cell at a fixed time interval (Δt), generates time series data for n cell voltages, and records it in the recording medium 221.

[0124] Next, the control circuit 220 repeats steps S20 to S50 a preset number of times to determine whether the normal diagnosis condition of Equation 4 is satisfied for all cell voltage sets that can be selected from the time-series data of the cell voltages, and cumulatively counts the number of cell voltage sets that do not satisfy the normal diagnosis condition.

[0125] First, in step S20, the control circuit 220 determines a cell voltage set V from the time series data of the cell voltages. k , Vk+1 , V k+2 Since the current k is 1, the selected cell voltage set is V1, V2, and V3.

[0126] Next, in step S30, the control circuit 220 determines whether the normal diagnosis condition of Equation 4 is satisfied for the current cell voltage set.

[0127] If the determination in step S30 is "No," the control circuit 220 increases the number of cell voltage sets that do not satisfy the normal diagnosis condition by one in step S40.

[0128] On the other hand, if the determination in step S30 is "YES," the control circuit 220 proceeds to step S50. In step S50, the control circuit 220 determines whether any cell voltage sets to be diagnosed remain. That is, the control circuit 220 determines whether the current cell voltage set is the last cell voltage set. The last cell voltage set is determined by determining whether V n-2 , V n-1 , V n is.

[0129] If the determination in step S50 is "YES," the control circuit 220 returns the process to step S20, selects the next set of cell voltages to be diagnosed, and repeats steps S30, S40, and S50 again. The current set of cell voltages is V2, V3, and V4. Steps S30, S40, and S50 are repeated until the determination in step S50 is "NO."

[0130] When the control circuit 220 has completed the diagnosis of all selectable cell voltage sets from the time-series data of the cell voltages, the control circuit 220 proceeds to step S60. In step S60, the control circuit 220 determines whether the number of cell voltage sets counted as not satisfying the normal diagnosis condition of Equation 4 is equal to or greater than a reference value. The setting of the reference value is as described above.

[0131] If the determination in step S60 is "YES," the control circuit 220 may diagnose the battery cell as having a voltage abnormality in step S70 and record the diagnosis result in the recording medium 221. The diagnosis result may include the time when the voltage abnormality was diagnosed and identification information of the battery cell.

[0132] The control circuit 220 may perform a voltage abnormality diagnosis on each of the battery cells included in the battery pack B. In addition, the control circuit 220 may refer to the diagnosis results recorded in the recording medium 221 and execute a post-diagnosis process.

[0133] That is, after completing the diagnosis of all the battery cells, the control circuit 220 may transmit the diagnosis results recorded in the recording medium 221 to an external device via the interface unit 330. The diagnosis results transmitted to the external device may include identification information of the battery cell where the voltage abnormality occurred and information about the time point at which the battery cell was diagnosed for the voltage abnormality. The diagnosis results transmitted to the external device may further include a warning message indicating that the battery pack B needs to be inspected or a corresponding diagnostic code. Alternatively, the identification information of the battery cell where the voltage abnormality occurred and detailed information about the time point at which the battery cell was diagnosed for the voltage abnormality may be excluded from the diagnosis results transmitted to the external device. When the external device is the vehicle controller 5, the vehicle controller 5 may output the diagnosis 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 diagnosis results via a display. In this case, the diagnosis results preferably include a diagnostic code indicating that a battery cell where the voltage abnormality occurred is present in the battery pack.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] Specifically, when the control circuit 220 starts diagnosing the voltage abnormality of the battery cells, it may perform steps S30 and S40 for the cell voltage set V1, V2, and V3 when the first, second, and third cell voltages V1, V2, and V3 are measured. Also, when the fourth cell voltage V4 is measured, it may perform steps S30 and S40 for the cell voltage set V2, V3, and V4. This process may be repeated every time a cell voltage is measured. That is, when the k+2th cell voltage V k+2 When measured, the cell voltage set V k, V k+1 , V k+2 Steps S30 and S40 may be performed for the last cell voltage Vn. This diagnostic process may be repeated until the last cell voltage Vn is measured. The total number of cell voltages to be measured may be preset. n After is measured, steps S60 and S70 may be performed.

[0138] 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.

[0139] According to the above-described embodiment, a battery cell in which a voltage abnormality has occurred can be easily diagnosed by analyzing the tendency of the cell voltage gradient between continuously measured cell voltages using a simple mathematical operation.

[0140] Additionally, embodiments of the present invention do not require a high-spec processor because the calculations used to diagnose the battery are not complex.

[0141] Furthermore, according to the embodiment of the present invention, the reliability of voltage abnormality diagnosis can be improved by using a mathematical operation that can amplify the tendency of the slope of the cell voltage.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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 indicative of a cell voltage of the battery cell; a recording medium configured to record the time-series data of the cell voltage; a control circuit operatively coupled to the voltage sensing circuit and the recording medium; The control circuit (i) receiving the voltage signal and recording time-series data of the cell voltage on the recording medium; (ii) selecting, as diagnostic data, a set of cell voltages measured at k-th, k+1-th, and k+2-th times from the time-series data (where k is an index indicating the order in which the cell voltages are measured, is a natural number equal to or greater than 1, and is assigned a plurality of values); (iii) determining a first voltage difference between the kth cell voltage and the k+1th cell voltage, and a second voltage difference between the k+1th cell voltage and the k+2th cell voltage; (iv) A battery diagnostic device configured to diagnose a battery cell as having an abnormal voltage when the count number of cell voltage sets for which the normal diagnosis condition that the pth power of the first voltage difference (p is a natural number greater than or equal to 1) is greater than the pth power of the second voltage difference is not met for a plurality of cell voltage sets is equal to or greater than a reference value.

2. 2. The battery diagnostic device according to claim 1, wherein p is 1.

3. 2. The battery diagnostic device according to claim 1, wherein p is a natural number equal to or greater than 2.

4. 2. The battery diagnostic device according to claim 1, wherein the reference value is 1.

5. 2. The battery diagnostic device according to claim 1, wherein the reference value is a natural number equal to or greater than two.

6. 2. The battery diagnostic device according to claim 1, wherein the control circuit is configured to select a plurality of the cell voltage sets from the time-series data of the cell voltages while increasing the k by 1 from 1 to n-2 (n is the number of voltage data included in the time-series data).

7. 2. The battery diagnostic device according to claim 1, wherein the control circuit is configured to perform the control logics (i) to (iv) when the operating state of the battery cell is switched from a charging or discharging state to an unloaded state.

8. an interface unit operatively coupled to the control circuit to facilitate communication with an external device; The battery diagnostic device according to claim 1 , wherein the control circuit is configured to transmit a diagnosis result to an external device through the interface unit when the battery cell is diagnosed as having an abnormal voltage.

9. an interface unit operably coupled to the control circuit; an output device operably coupled to the interface portion; 2. The battery diagnostic device according to claim 1, wherein the control circuit is configured to output a diagnosis result visually or audibly through the output device when the battery cell is diagnosed as having an abnormal voltage.

10. A battery pack comprising the battery diagnostic device according to any one of claims 1 to 9.

11. A motor vehicle comprising the battery pack of claim 10.

12. (a) receiving an input of a voltage signal indicating a cell voltage of a battery cell from a voltage sensing circuit, and recording time-series data of the cell voltage on a recording medium; (b) selecting a set of cell voltages measured at k-th, k+1-th, and k+2-th times from the time-series data as diagnostic data (where k is an index indicating the order of cell voltage measurement, is a natural number equal to or greater than 1, and may be assigned a plurality of values); (c) determining a first voltage difference between the kth cell voltage and the k+1th cell voltage, and a second voltage difference between the k+1th cell voltage and the k+2th cell voltage; (d) diagnosing a battery cell as having a voltage abnormality if the count number of cell voltage sets for which the normal diagnosis condition that the pth power of the first voltage difference (p is a natural number greater than or equal to 1) is greater than the pth power of the second voltage difference is not met for a plurality of cell voltage sets is equal to or greater than a reference value.

13. The battery diagnostic method of claim 12, wherein p is 1.

14. The battery diagnostic method according to claim 12, wherein p is a natural number equal to or greater than 2.

15. The battery diagnostic method according to claim 12 , wherein the reference value is 1.

16. The battery diagnostic method according to claim 12, wherein the reference value is a natural number equal to or greater than 2.

17. 17. The battery diagnostic method according to claim 12, wherein the plurality of cell voltage sets are selected from the time-series data of the cell voltages while increasing k by 1 from 1 to n-2 (n is the number of cell voltages included in the time-series data).

18. 17. The battery diagnostic method according to claim 12, wherein steps (a) to (d) are performed when an operating state of the battery cell is switched from a charging or discharging state to an unloaded state.

19. The battery diagnostic method of claim 12 , further comprising transmitting a diagnosis result to an external device when the battery cell is diagnosed as having an abnormal voltage.

20. The battery diagnostic method of claim 12 , further comprising the step of visually or audibly outputting a diagnosis result through an output device when the battery cell is diagnosed as having an abnormal voltage.

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