Battery diagnostic device, battery pack including the same, electric vehicle, and battery diagnostic method

Abstract

According to an aspect of the present application, a battery diagnostic apparatus for a battery including a parallel connection of a plurality of unit cells, the battery diagnostic apparatus comprising: a data acquisition unit configured to collect charge and discharge data, the charge and discharge data including a voltage time series indicative of a voltage across two terminals of the battery as a function of time and a current time series indicative of a charge and discharge current flowing through the battery as a function of time; and a data processing unit configured to determine, based on the charge and discharge data, an estimated capacity value indicative of a full charge capacity of the battery. The data processing unit is configured to monitor a change in the estimated capacity value over time to diagnose any abnormalities in the parallel connection.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2021-0120039, filed with the Korean Intellectual Property Office on September 8, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to detecting anomalies in the parallel structure of cell units in a battery based on the change in the battery's full-charge capacity over time. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, cameras, and mobile phones has grown rapidly, and with the development of electric vehicles, energy storage batteries, robots, and satellites, a great deal of research is underway on high-performance batteries that can be repeatedly recharged.

[0004] Currently, commercially available battery packs include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have almost no or no memory effect. Therefore, due to their advantages of being able to be recharged at any time when convenient, having a very low self-discharge rate, and high energy density, they have received more attention than nickel-based batteries.

[0005] Batteries are manufactured by encapsulating an electrolyte and electrode assembly together in a packaging material and then sealing the packaging material. The electrode assembly comprises multiple cell units connected in parallel, and is referred to as a parallel structure of cell units. Here, a cell unit refers to the smallest unit in an energy storage device that can be individually recharged. For example, a cell unit can be a full cell comprising at least one of a single cell or a dual cell.

[0006] Anomalies can occur in the parallel structure of a battery due to various factors, such as errors in battery manufacturing, aging caused by repeated charging and discharging, and external influences. Battery capacity anomalies can be divided into two categories. The first category refers to temporary failures that prevent the battery from contributing to charging / discharging due to micro-damage and / or incomplete open circuit faults in the connection points (e.g., electrode terminals) of some cells in the parallel structure. The second category refers to permanent failures that prevent the battery from contributing to charging / discharging due to irreversible damage to some cells in the parallel structure.

[0007] In particular, when the parallel structure of the battery has a Type II anomaly, compared to a Type I capacity anomaly, charging / discharging is concentrated on the normal cell, leading to an increased risk of battery fire and explosion. Summary of the Invention

[0008] Technical issues

[0009] This disclosure is designed to solve the above-mentioned problems, and therefore aims to provide a battery diagnostic device and a battery diagnostic method for detecting abnormalities in the parallel structure of cell units in a battery in advance by repeatedly determining the full charge capacity of the battery and monitoring the change of the full charge capacity over time.

[0010] These and other objects and advantages of this disclosure can be understood from the following description, and these objects and advantages will become apparent from embodiments of this disclosure. Furthermore, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0011] Technical solution

[0012] According to one aspect of this disclosure, a battery diagnostic device for a battery includes a parallel structure of cell units. The battery diagnostic device includes: a data acquisition unit configured to collect charging / discharging data, the charging / discharging data including a voltage time series and a current time series, the voltage time series indicating the change of voltage across the battery over time, and the current time series indicating the change of charging / discharging current flowing through the battery over time; and a data processing unit configured to determine an estimated capacity value indicating the full-charge capacity of the battery based on the charging / discharging data. The data processing unit is configured to diagnose anomalies in the parallel structure by monitoring changes in the estimated capacity value over time.

[0013] The data processing unit can be configured to determine the cumulative current value and the state of charge (SOC) change value of the battery by inputting the charge / discharge data into the capacity estimation model, and to determine the estimated capacity value based on the ratio of the cumulative current value to the SOC change value.

[0014] The data processing unit can be configured to diagnose anomalies in the parallel structure based on two capacity values ​​estimated at a first time and a second time, wherein the first time and the second time are separated by a second time interval equal to or greater than the first time interval, shifted by the first time interval.

[0015] The data processing unit can be configured to determine a threshold capacity value for a second time that is less than the estimated capacity value at the first time, and to diagnose anomalies in the parallel structure by comparing the estimated capacity value at the second time with the threshold capacity value.

[0016] The data processing unit can be configured to determine the threshold capacity value by subtracting a reference capacity value from the estimated capacity value at the first time.

[0017] The data processing unit can be configured to determine the threshold capacity value by multiplying the estimated capacity value at the first time by a reference factor less than 1.

[0018] When the estimated capacity value at the second time is less than the threshold capacity value, the data processing unit can be configured to increase the diagnostic count and, in response to the diagnostic count reaching the threshold count, diagnose the parallel structure fault.

[0019] The data processing unit can be configured to, when a fault in the parallel structure is diagnosed, determine the number of faulty cell units among a plurality of cell units based on two estimated capacity values ​​that represent the maximum reduction in full charge capacity at two past moments that are equal to or less than the second time interval.

[0020] According to another aspect of this disclosure, a battery pack includes the battery diagnostic device.

[0021] An electric vehicle according to another aspect of this disclosure includes the battery pack.

[0022] According to another aspect of this disclosure, a battery diagnostic method for a battery comprising a parallel structure of cell units includes the following steps: collecting charging / discharging data, the charging / discharging data including a voltage time series and a current time series, the voltage time series indicating the change of voltage across the battery over time, and the current time series indicating the change of charging / discharging current flowing through the battery over time; determining an estimated capacity value indicating the full-charge capacity of the battery based on the charging / discharging data; and diagnosing anomalies in the parallel structure by monitoring the change of the estimated capacity value over time.

[0023] Determining an estimated capacity value indicating the full charge capacity of the battery may include the following steps: determining the cumulative current value and the state of charge (SOC) change value of the battery by inputting the charge / discharge data into a capacity estimation model; and determining the estimated capacity value based on the ratio of the cumulative current value to the SOC change value.

[0024] The steps for diagnosing anomalies in the parallel structure can be based on two capacity values ​​estimated at a first time and a second time, the first time and the second time being separated by a second time interval equal to or greater than the first time interval offset from the first time interval.

[0025] The steps for diagnosing anomalies in the parallel structure may include: determining a threshold capacity value for a second time that is less than the estimated capacity value at the first time; and diagnosing anomalies in the parallel structure by comparing the estimated capacity value at the second time with the threshold capacity value.

[0026] Technical effect

[0027] According to at least one embodiment of this disclosure, anomalies in the parallel structure of cell units in a battery can be detected by repeatedly determining the full charge capacity of the battery and monitoring the change of the full charge capacity over time.

[0028] Furthermore, according to at least one embodiment of this disclosure, the risk of fire and explosion of the battery can be eliminated in advance by taking appropriate protective measures in response to the detection of anomalies in the parallel structure.

[0029] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand these and other effects from the appended claims. Attached Figure Description

[0030] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the detailed description of the present disclosure below, are intended to provide a further understanding of the technical aspects of the present disclosure; therefore, the present disclosure should not be construed as being limited to the drawings.

[0031] Figure 1 A diagram of an electric vehicle according to this disclosure is shown as an example.

[0032] Figure 2 It is shown as an example Figure 1 A schematic diagram of the battery shown.

[0033] Figure 3 This is a diagram to refer to when describing the first capacity abnormality of the battery (incomplete open circuit fault).

[0034] Figure 4 This is a diagram to refer to when describing the second capacity abnormality (complete open circuit fault) of the battery.

[0035] Figure 5 This is an exemplary chart used to describe the relationship between abnormal battery capacity and full charge capacity.

[0036] Figure 6 This is an exemplary flowchart illustrating a battery diagnostic method according to an embodiment of the present disclosure. Detailed Implementation

[0037] The exemplary embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. Before this description, it should be understood that the terms and vocabulary used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but rather as being interpreted based on the meaning and concepts consistent with the technical aspects of this disclosure, on the basis that the inventors are permitted to appropriately define the terms for the best interpretation.

[0038] Therefore, the embodiments described herein and the descriptions shown in the accompanying drawings are merely exemplary embodiments of this disclosure and are not intended to fully describe the technical aspects of this disclosure. It should be understood that various other equivalents and modifications can be made thereto at the time this application was filed.

[0039] Ordinal terms such as “first” and “second” are used to distinguish one element from another among various elements, but are not intended to limit the elements.

[0040] Unless the context clearly indicates otherwise, it will be understood that when the term "comprising" is used in this specification, it specifies the presence of the stated element but does not preclude the presence or addition of one or more other elements. Furthermore, as used herein, the term "unit" refers to at least one processing unit that performs at least one function or operation and may be implemented in hardware and software, alone or in combination.

[0041] Furthermore, as will be further understood throughout the specification, when an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element present.

[0042] Figure 1 A diagram of an electric vehicle according to this disclosure is shown as an example.

[0043] Reference Figure 1 The electric vehicle 1 includes a vehicle controller 2, a battery pack 10, and an electrical load 30. The charging / discharging terminals P+ and P- of the battery pack 10 can be electrically connected to a charger 40 via a charging cable. The charger 40 can be included in the electric vehicle 1 or provided in a charging station outside the electric vehicle 1.

[0044] The vehicle controller 2 (e.g., an electronic control unit (ECU)) is configured to send a key-on signal to the battery management system 100 in response to the user switching the ignition button (not shown) of the electric vehicle 1 to the ON position. The vehicle controller 2 is also configured to send a key-off signal to the battery management system 100 in response to the user switching the ignition button to the OFF position. The charger 40 can supply constant-current or constant-voltage charging power to the battery pack 10 via communication with the vehicle controller 2 through the charging / discharging terminals P+ and P-.

[0045] The battery pack 10 includes a battery group BG, a relay 20, and a battery management system 100.

[0046] A battery group BG includes at least one battery B. For example, battery B is not limited to a specific type and can include any type of cell that can be recharged, such as a lithium-ion cell. Figure 1 The battery group BG is shown as batteries B1~B1.N A series connection structure (N is a natural number of 2 or greater). Multiple batteries B1~B N They can be manufactured to have the same electrical and chemical specifications. Below, we will discuss multiple batteries B1~B... N In the common description, the symbol 'B' is attached to the battery.

[0047] Relay 20 is connected in series to battery group BG via the power path connecting battery group BG and converter 31. Figure 1 The diagram shows a relay 20 connected between the positive terminal of the battery pack BG and one of the charging / discharging terminals, terminal P+. The on / off control of relay 20 is performed in response to a switching signal from the battery management system 100. Relay 20 can be a mechanical contactor that is turned on / off by the magnetic field of a coil, or a semiconductor switch such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0048] Electrical load 30 includes an inverter 31 and an electric motor 32. The inverter 31 is provided to convert direct current (DC) power from battery cells BG included in the battery pack 10 into alternating current (AC) power in response to commands from the battery management system 100 or the vehicle controller 2. The electric motor 32 operates using the AC power from the inverter 31. The electric motor 32 may include, for example, a three-phase AC motor.

[0049] The battery management system 100 includes a sensing circuit 110, a memory 120, and a computing circuit 130. The battery management system 100 may also include a communication circuit 140. The battery management system 100 is an example of a battery diagnostic device according to this disclosure.

[0050] Sensing circuit 110 is configured to collect at least one of physical quantities observable from battery B. The physical quantities of the battery include the voltage, current, and / or temperature of battery B. Sensing circuit 110 and memory 120 are examples of data acquisition units according to this disclosure. Sensing circuit 110 includes a voltage detector 111 and a current detector 112. Sensing circuit 110 may also include a temperature detector 113.

[0051] Voltage detector 111 is connected to multiple batteries B1~B1 included in battery group BG. N The positive and negative terminals of each are used to detect multiple batteries B1~B1 respectively. N The voltage across the terminals or the battery voltage V1~V N And generate battery voltages V1~V N The voltage signal of the voltage value.

[0052] Current detector 112 is connected in series to battery group BG via the current path between battery group BG and converter 31. Current detector 112 is configured to detect the charging / discharging current flowing through battery group BG and generate a current signal indicating the value of the charging / discharging current. Due to the multiple batteries B1~B N Because they are connected in series, a common charging / discharging current flows to multiple batteries B1~B2. N The current detector 112 may include at least one of the known current detection devices, such as a shunt resistor or a Hall effect device.

[0053] Temperature detector 113 is configured to detect the temperature of the battery or the battery pack BG and generate a temperature signal indicating the detected battery temperature. Temperature detector 113 can be positioned within a predetermined distance from the battery pack BG to detect temperatures close to the actual temperature of the battery pack BG. For example, temperature detector 113 can be attached to the surface of at least one battery B included in the battery pack BG and can detect the surface temperature of battery B as the battery temperature. Temperature detector 113 can include at least one known temperature sensing device such as a thermocouple, a thermistor, or a bimetallic device.

[0054] The memory 120 may include, for example, at least one storage medium selected from flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). The memory 120 can record charging / discharging data of battery B by arranging the measured physical quantities of the battery collected by sensing circuit 110 over time. The charging / discharging data includes a voltage time series indicating the change of battery voltage across battery B over time and a current time series indicating the change of charging / discharging current flowing through battery B over time. The memory 120 may store data indicating the results of calculation operations by computing circuit 130. The memory 120 may store programs, algorithms, diagnostic logic, and / or functions required for the control, management, and diagnosis of battery B.

[0055] Communication circuit 140 is configured to support wired or wireless communication between computing circuit 130 and vehicle controller 2. Wired communication may be, for example, Controller Area Network (CAN) communication, and wireless communication may be, for example, Zigbee or Bluetooth communication. Of course, the communication protocol is not limited to a specific type and may include any type of communication protocol that supports wired / wireless communication between computing circuit 130 and vehicle controller 2. Communication circuit 140 may include output devices (e.g., a display, a speaker) to provide information received from computing circuit 130 and / or vehicle controller 2 in a format recognizable to the user (driver).

[0056] The computing circuit 130 may be operatively connected to at least one of the relay 20, the sensing circuit 110, and the communication circuit 140. Ooperative connection refers to a direct / indirect connection for unidirectional or bidirectional transmission and reception of signals. The computing circuit 130 may be referred to as an "on-board controller" and is an example of a data processing unit according to this disclosure.

[0057] The computing circuit 130 can periodically collect voltage signals from voltage detector 111, current signals from current detector 112, and / or temperature signals from temperature detector 113 at predetermined time intervals or non-periodicly at irregular time intervals during the charging, discharging, and / or resting periods of the battery pack BG. That is, the computing circuit 130 can use the analog-to-digital converter (ADC) provided therein to acquire the detected voltage values, detected current values, and / or detected temperature values ​​from the analog signals collected by detectors 111, 112, and 113 and record them in the memory 120.

[0058] The computing circuit 130 may be implemented as hardware using at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions.

[0059] When electrical load 30 and / or charger 3 are operating while relay 20 is on, battery pack BG enters charging or discharging mode. When relay 20 is off, battery pack BG is switched to rest mode.

[0060] The computing circuit 130 can activate the relay 20 in response to a key-on signal. The computing circuit 130 can deactivate the relay 20 in response to a key-off signal. The key-on signal is a signal requesting a switch from idle to charging or discharging. The key-off signal is a signal requesting a switch from charging or discharging to idle. Alternatively, the vehicle controller 2 can replace the computing circuit 130 in performing the on / off control of the relay 20.

[0061] The remote battery monitor 300 is another example of a battery diagnostic device according to this disclosure and may be provided in the form of a cloud server outside of the electric vehicle 1. The remote battery monitor 300 includes a communication circuit 310, a memory 320, and a computing circuit 330. The communication circuit 310 and the memory 320 are another example of a data acquisition unit according to this disclosure. The computing circuit 330 is another example of a data processing unit according to this disclosure and may be referred to as an "external controller". The communication circuit 310 is connected to the communication circuit 140 of the battery management system 100 via a wired / wireless communication channel to collect charging / discharging data of battery B from the battery management system 100 and to record the collected charging / discharging data in the memory 320. In the diagnosis of anomalies in the parallel structure 200 included in at least one battery B of the battery group BG, the computing circuit 330 performs the operation and functions commonly found in the computing circuit 130 of the battery management system 100. Note that the computing circuit 130 described below may share a common description with the computing circuit 330.

[0062] Figure 2 It is shown as an example Figure 1 A schematic diagram of the battery shown. Figure 3 This is a diagram used to describe the first capacity anomaly of the battery (incomplete open circuit fault), and Figure 4 This is a diagram to refer to when describing the second capacity abnormality (complete open circuit fault) of the battery.

[0063] Reference Figure 2 Battery B includes electrode assembly 200, positive electrode lead 210, negative electrode lead 220, and encapsulation material 230.

[0064] Electrode assembly 200 is a unit cell UC1~UC M Example of a parallel structure (M is a natural number of 2 or greater). The cell UC includes a separator 203, a positive plate 201, and a negative plate 202 that is insulated from the positive plate 201 by the separator 203.

[0065] The positive electrode plate 201 has a positive electrode connector 205 connected to one end of the positive electrode lead 210, and the negative electrode plate 202 has a negative electrode connector 206 connected to one end of the negative electrode lead 220.

[0066] In multiple cell units UC1~UC M With the positive terminal 205 and negative terminal 206 connected to one end of each of the positive lead 210 and negative lead 220, the electrode assembly 200 is contained within the encapsulation material 230 along with the electrolyte. The opposite ends of each of the positive lead 210 and negative lead 220 exposed through the encapsulation material 230 are provided as the positive and negative terminals of the battery B.

[0067] ReferenceFigure 3 The first capacity anomaly of electrode assembly 200 is caused by multiple cell units UC1~UC1. M Micro-damage and / or incomplete open-circuit faults in the electrode terminals 205 and 206 of some of the cell units UC1 and UC2 cause irregular and large changes in the contact resistance R1 and R2 between cell units UC1 and UC2 and the electrode leads 210 and 220. In the case of incomplete open-circuit faults, the cut portions of electrode terminals 205 and 206 are not spaced apart from each other, and as the battery B contracts and expands, they connect and disconnect, and the contact area changes during connection. During the period when the contact resistance at cell units UC1 and UC2 is kept low, all cell units UC1~UC2... M The charging and discharging are almost uniform, and as the contact resistances R1 and R2 increase, the individual cells UC1 and UC2 behave more like the other individual cells UC3 to UC4. M When the circuit is broken, the capacity of battery B exhibits irregular behavior, such as sudden increases or decreases, which are clearly dependent on the contact resistances R1 and R2 of the cells UC1 and UC2. For example, during periods of high tensile strength between the electrode terminals 205 and 206 and the electrode leads 210 and 220 of cells UC1 and UC2 due to the bulging of battery B, the contact resistances R1 and R2 of cells UC1 and UC2 increase, and conversely, as the tensile strength gradually decreases, the contact resistances R1 and R2 of cells UC1 and UC2 decrease.

[0068] Reference Figure 4 The second capacity anomaly of electrode assembly 200 is equivalent to multiple cell units UC1~UC M The irreversible damage to some of the cell units UC1 and UC2, specifically, the irreversible damage to the charging / discharging current path between cell units UC1 and UC2 and electrode leads 210 and 220 due to a complete open-circuit fault in cell units UC1 and UC2. The difference between an incomplete open-circuit fault and a complete open-circuit fault is that the electrode terminals 205 and 206 or the electrode plates 201 and 202 of cell units UC1 and UC2 are broken into fragments too far apart to be reconnected. The occurrence of a second capacity anomaly caused by cell units UC1 and UC2 at some point during the manufacture or use of battery B indicates that cell units UC1 and UC2 have irreversibly separated from electrode leads 210 and 220. Therefore, since cell units UC1 and UC2 do not contribute to the charging / discharging of battery B from the specific time the second capacity anomaly occurs, the capacity of battery B depends only on the remaining cell units UC3 to UC2. M The capacity.

[0069] The computing circuit 130 periodically or non-periodically repeats the process of determining an estimated capacity value indicating the full charge capacity (FCC) of the battery by applying a capacity estimation model to charge / discharge data. That is, the computing circuit 130 monitors the change of the estimated capacity value over time.

[0070] A capacity estimation model is an algorithm that, as the output of input charge / discharge data, provides an estimated capacity value and is a combination of functions.

[0071] Specifically, the capacity estimation model may include: (i) a first function that calculates the cumulative current value of the charging / discharging current of battery B over a past variable time period or a predetermined time period based on the current time series of battery B; (ii) a second function that calculates the open-circuit voltage (OCV) of battery B over a past variable time period or a predetermined time period based on the voltage time series and / or current time series of battery B; (iii) a third function that calculates the state of charge (SOC) of battery B based on the OCV of battery B using a preset OCV-SOC relationship table; and (iv) a fourth function that calculates the estimated full-charge capacity of battery B based on the ratio of the cumulative current value calculated separately over a common time period to the SOC change value, i.e., the estimated capacity value. The following equation is an example of the fourth function.

[0072] <Equation>

[0073]

[0074] In the above equation, ΔAh t1-t2 ΔSOC is the cumulative current value of the charging / discharging current repeatedly measured between two time periods t1 and t2. t1-t2 It is the change in SOC over the time interval between two times t1 and t2, and FCC t2 This is an estimated capacity value indicating the full charge capacity at time t2. Time t1 is earlier than time t2, and it can satisfy ΔAh. t1-t2 The absolute value is equal to or greater than the reference cumulative value and / or ΔSOC t1-t2 The absolute value is equal to or greater than the latest time of the reference change value. The reference cumulative value and the reference change value can be preset to prevent FCC interference. t2 The accuracy due to ΔAh t1-t2 and / or ΔSOC t1-t2 It deteriorates due to its very small absolute value.

[0075] When calculating the cumulative current value, the charging current can be set to a positive value and the discharging current can be set to a negative value. Time t2 is the time for calculating the full charge capacity. When the full charge capacity is calculated repeatedly at each first time interval, it will be readily understood by those skilled in the art that time t2 is shifted by the first time interval.

[0076] In the example, with the cumulative current and SOC change over a common past period being +100 Ah [ampere-hours] and +80% respectively, the estimated full-charge capacity is 125 Ah. In another example, with the cumulative current and SOC change over a common past period being -75 Ah [ampere-hours] and -60% respectively, the estimated full-charge capacity is also 125 Ah.

[0077] Full charge capacity indicates the maximum possible capacity of battery B, that is, the remaining capacity of battery B at 100% SOC. Normally, the full charge capacity decreases gradually as battery B deteriorates. Therefore, when the full charge capacity decreases more than the predetermined level in a short period of time, it indicates that a first capacity anomaly or a second capacity anomaly has occurred.

[0078] Figure 5 This is an exemplary chart used to describe the relationship between abnormal battery capacity and full charge capacity.

[0079] Reference Figure 5 Curve 500 shows the change in the full-charge capacity of a normal battery over time. To aid understanding, curve 500 is plotted in a simplified form to show that the full-charge capacity of a normal battery decreases linearly over time.

[0080] Curve 510 shows the change in the full-charge capacity of battery B over time when the first capacity anomaly and the second capacity anomaly occur sequentially. Curve 510 is described as follows: Figure 3 The diagram illustrates the full-charge capacity of battery B, which exhibits a first capacity anomaly due to micro-damage and / or incomplete open-circuit faults in cells UC1 and UC2. In curve 510, the full-charge capacity decreases smoothly between time ta (e.g., at the battery's manufacturing time) and time tb, then drops sharply between time tb and time tc, and rises sharply between time tc and time td. That is, the decrease in full-charge capacity between time tb and time tc almost recovers between time tc and time td. This is because the contact resistances R1 and R2 of cells UC1 and UC2 increase sharply between time tb and time tc and return to normal levels between time tc and time td, as described above. Figure 3 As stated above.

[0081] When the first capacity anomaly persists for an extended period, it can develop into a second capacity anomaly (becoming worse). Describing curve 510, after time td, from time te to time tf, in a manner similar to the time interval between time tb and time tc, there is a sharp drop in full-charge capacity. In contrast to the behavior between time tc and td, even after time tf when the sharp drop in full-charge capacity stops, the full-charge capacity fails to return to normal levels and has a slope similar to curve 500. This is caused by a complete open-circuit fault (i.e., the second capacity anomaly) occurring in cells UC1 and UC2 at or approximately time te, as described above. Figure 4 As stated above.

[0082] The calculation circuit 130 determines whether a first capacity anomaly and / or a second capacity anomaly of the parallel structure 200 occurs by monitoring the change (time series) of the full charge capacity (i.e., the estimated capacity value) over time according to curve 510. That is, the battery diagnostic device according to this disclosure can execute diagnostic logic to perform battery anomaly diagnosis according to this disclosure in the parallel structure 200, and specifically, identify (or diagnose) whether an anomaly is present in the cell included in the parallel structure 200 based on the diagnostic logic.

[0083] In other words, the battery diagnostic device according to this disclosure can identify a parallel structure 200 including at least one faulty cell or a large number of faulty cells greater than a threshold number by diagnosing the parallel structure 200 based on the diagnostic logic of this disclosure, thereby diagnosing abnormal parallel structure 200 (or abnormalities in parallel structure 200).

[0084] Specifically, the computing circuit 130 can determine whether a first capacity anomaly and / or a second capacity anomaly of the parallel structure 200 has occurred by applying diagnostic logic to two estimated capacity values ​​at a first time and a second time, the first time and the second time being offset by a second time interval equal to or greater than the first time interval. The second time is later than the first time by the second time interval, and each of the first time and the second time can be configured by the computing circuit 130 to increase the first time interval by each first time interval. The first time interval can be equal to the charging / discharging data collection cycle (or the estimated capacity value calculation cycle), and the second time interval can be an integer multiple of the first time interval (e.g., 10 times).

[0085] The diagnostic logic may include: (i) a first routine that determines a threshold capacity value for a second time that is less than the estimated capacity value for a first time; and (ii) a second routine that compares the estimated capacity value for the second time with the threshold capacity value for the second time.

[0086] In the first example, the threshold capacity value for the second time period can be equal to the estimated capacity value for the first time period minus the reference capacity value, or the estimated capacity value for the first time period multiplied by a reference factor less than 1. The reference capacity value can consider the cell units UC1~UC1 included in battery B. M The total number M and the design capacity (full charge capacity when brand new) of battery B are recorded as preset values ​​in memory 120. Reference factors can be taken into account for the cell units UC1~UC1 included in battery B. M The total number M is recorded in memory 120 as a preset value (e.g., (M-1) / M, (M-2) / M). Figure 5 Curve 520 shows the change of the threshold capacity value over time by applying the first routine to curve 510.

[0087] When the estimated capacity value at the second time is less than the threshold capacity value for the second time, the calculation circuit 130 can determine that at least one of the first capacity anomaly or the second capacity anomaly occurs in the parallel structure 200.

[0088] Whenever the estimated capacity value at the second time is less than the threshold capacity value for the second time, the calculation circuit 130 may increment the diagnostic count by 1. Whenever the estimated capacity value at the second time is equal to or greater than the threshold capacity value for the second time, the calculation circuit 130 may reset the diagnostic count to a starting value (e.g., 0) or decrement the diagnostic count by 1. In response to the estimated capacity value at the second time rising to or exceeding the threshold capacity value for the second time before the diagnostic count reaches the threshold count, the calculation circuit 130 may determine that the anomaly type of the parallel structure 200 is a first capacity anomaly. The calculation circuit 130 may determine that a second capacity anomaly of the parallel structure 200 has occurred in response to the diagnostic count reaching the threshold count (e.g., 5).

[0089] exist Figure 5 In the diagram, times ta+, tb+, tc+, td+, te+, and tf+ represent the times when ta, tb, tc, td, te, and tf are offset in the positive direction by a second time interval, respectively. During the time interval between time tx and time ty, curve 510 lies below curve 520. Therefore, from time tx to time ty, the diagnostic count increments by 1 at each first time interval. The calculation circuit 130 can activate a predetermined protection function related to a second capacity anomaly of battery B in response to the diagnostic count reaching a threshold count before time ty.

[0090] Figure 6 This is an exemplary flowchart illustrating a battery diagnostic method according to an embodiment of the present disclosure. Figure 6 The method can be executed iteratively at the first time interval.

[0091] ReferenceFigures 1 to 6 In step S610, the data acquisition unit collects charging / discharging data of battery B. When the battery management system 100 is used as a battery diagnostic device, the sensing circuit 110 and the memory 120 correspond to the data acquisition unit. When the remote battery monitor 300 is used as a battery diagnostic device, the communication circuit 310 and the memory 320 correspond to the data acquisition unit.

[0092] In step S620, the data processing unit determines an estimated capacity value indicating the full-charge capacity of battery B. When the battery management system 100 is used as a battery diagnostic device, the calculation circuit 130 corresponds to the data processing unit. When the remote battery monitor 300 is used as a battery diagnostic device, the calculation circuit 330 corresponds to the data processing unit. Step S620 may include steps S622 and S624. In step S622, the data processing unit determines the cumulative current value and SOC change value of battery B by inputting charge / discharge data into the capacity estimation model. In step S624, the data processing unit determines an estimated capacity value indicating the full-charge capacity of battery B from the ratio of the cumulative current value to the SOC change value of battery B. The time series of the estimated capacity value is recorded in the data acquisition unit.

[0093] In step S630, the data processing unit detects anomalies in the parallel structure 200 by monitoring changes in the estimated capacity value over time. Step S630 may include steps S632, S634, S636, S638, and S639. In step S632, the data processing unit determines a threshold capacity value for a second time that is less than the estimated capacity value at a first time. For example, the second time may be the time when the estimated capacity value is calculated in the current cycle, and the first time may be the time when the estimated capacity value was calculated 10 cycles ago. In step S634, the data processing unit compares the estimated capacity value at the second time with the threshold capacity value for the second time. If the estimated capacity value at the second time is less than the threshold capacity value for the second time, it indicates that at least one of a first capacity anomaly and a second capacity anomaly occurs in the parallel structure 200. If the value in step S634 is "yes", step S636 is executed. Otherwise, step S638 may be executed. In step S636, the data processing unit increments the diagnostic count by 1. In step S638, the data processing unit resets the diagnostic count. In step S639, the data processing unit determines whether the diagnostic count has reached the threshold count. A value of "yes" in step S639 indicates that a complete open-circuit fault or a second capacity abnormality has been diagnosed in at least one cell UC of the parallel structure 200.

[0094] In step S640, the data processing unit may activate a predetermined protection function. This protection function may include, for example, outputting a warning message and shutting off relay 20. The data processing unit can determine the capacity values ​​of multiple cell UC1~UC2 based on two estimated capacity values ​​estimated at two past times (e.g., te, tf) at a time interval equal to or less than a second time interval, where the maximum reduction in the estimated capacity value was found. M The number of faulty cells (complete open circuit faults) can be determined. Multiple cells UC1~UC... M The number of faulty cells (complete open-circuit faults). The number of faulty cells can be determined to be equal to or greater than ΔAh. max / (Ah p The largest integer ( / M). Ah p It is the estimated capacity value for the earlier of two times (e.g., te, tf), ΔAh. max It is the maximum reduction in full-charge capacity over the time interval between two times (e.g., te, tf) prior to the anomaly detection timing in the parallel structure 200, and is the result of subtracting the estimated capacity value of the later time tf from the estimated capacity value of the earlier time te. For example, Ah p =122 Ah,ΔAh max =27 Ah, M=10, 2≤27 Ah / (122 Ah / 10)<3, therefore the number of faulty cells is determined to be 2. Warning messages may include multiple batteries B1~B N Identification information of the faulty battery (e.g., B1). The warning message may include data indicating the number of faulty cell units (e.g., UC1, UC2) included in the parallel structure 200 of the faulty battery (e.g., B1).

[0095] The embodiments of this disclosure described above are not limited to being implemented by devices and methods, but can also be implemented by a program that performs functions corresponding to the configuration of the embodiments of this disclosure or by a recording medium that records the program, and such implementation can be easily carried out by those skilled in the art from the disclosure of the above embodiments.

[0096] Although this disclosure has been described above with respect to a limited number of embodiments and accompanying drawings, this disclosure is not limited thereto and it will be apparent to those skilled in the art that various modifications and alterations can be made to it within the technical aspects of this disclosure and within the equivalent scope of the appended claims.

[0097] Furthermore, since those skilled in the art can make numerous substitutions, modifications, and alterations to the disclosure described above without departing from the technical aspects of this disclosure, this disclosure is not limited to the above embodiments and drawings, and all or some embodiments can be selectively combined to allow various variations.

[0098] [Explanation of reference numerals in the attached figures]

[0099] 1: Electric vehicle 2: Vehicle controller

[0100] 10: Battery pack 20: Relay

[0101] 30: Electrical load; 40: Charger

[0102] 100: Battery Management System (Example of a "Battery Diagnostic Device")

[0103] 110: Sensing circuit; 120: Memory

[0104] 130: Computing circuits; 140: Communication circuits

[0105] 300: Remote battery monitor (another example of a "battery diagnostic device")

[0106] 310: Communication circuit; 320: Memory

[0107] 330: Calculation Circuit

Claims

1. A battery diagnostic device for a battery, the battery comprising a parallel structure of unit cells, the battery diagnostic device comprising: A data acquisition unit configured to collect charging / discharging data; as well as A data processing unit is configured to determine an estimated capacity value indicating the full-charge capacity of the battery based on the charging / discharging data. The data processing unit is configured to diagnose anomalies in the parallel structure by monitoring changes in the estimated capacity value over time. The data processing unit is configured to diagnose anomalies in the parallel structure based on two estimated capacity values, a first time and a second time, wherein the first time and the second time are separated by a second time interval equal to or greater than the first time interval, offset from the first time interval. The data processing unit is configured as follows: Determine a threshold capacity value for the second time that is less than the estimated capacity value at the first time, and Anomalies in the parallel structure are diagnosed by comparing the estimated capacity value at the second time with the threshold capacity value.

2. The battery diagnostic device according to claim 1, wherein, The charging / discharging data includes a voltage time series and a current time series. The voltage time series indicates the change of voltage across the battery over time, and the current time series indicates the change of charging / discharging current flowing through the battery over time.

3. The battery diagnostic device according to claim 1, wherein, The data processing unit is configured to determine the cumulative current value and the state of charge (SOC) change value of the battery by inputting the charge / discharge data into the capacity estimation model, and to determine the estimated capacity value based on the ratio of the cumulative current value to the SOC change value.

4. The battery diagnostic device according to claim 1, wherein, The data processing unit is configured to determine the threshold capacity value by subtracting a reference capacity value from the estimated capacity value at the first time.

5. The battery diagnostic device according to claim 1, wherein, The data processing unit is configured to determine the threshold capacity value by multiplying the estimated capacity value at the first time by a reference factor less than 1.

6. The battery diagnostic device according to claim 1, wherein, The data processing unit is configured as follows: When the estimated capacity value at the second time is less than the threshold capacity value, the diagnostic count is increased, and In response to the diagnostic count reaching a threshold count, a fault is diagnosed in the parallel structure.

7. The battery diagnostic device according to claim 1, wherein, The data processing unit is configured to, when a fault is diagnosed in the parallel structure, determine the number of faulty cell units among a plurality of cell units based on two estimated capacity values ​​that represent the maximum reduction in full charge capacity at two past moments that are equal to or less than the second time interval.

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

9. An electric vehicle comprising the battery pack according to claim 8.

10. A battery diagnostic method for a battery comprising a parallel structure of individual cells, the battery diagnostic method comprising the following steps: Collect charging / discharging data; Based on the charging / discharging data, an estimated capacity value indicating the full-charge capacity of the battery is determined; as well as Anomalies in the parallel structure are diagnosed by monitoring changes in the estimated capacity value over time. The abnormality in the parallel structure is diagnosed based on two estimated capacity values ​​at a first time and a second time. The first and second time intervals are separated by a second time interval equal to or greater than the first time interval, which is offset from the first time interval. The step of diagnosing abnormalities in the parallel structure includes the following steps: Determine a threshold capacity value for the second time that is less than the estimated capacity value at the first time; and Anomalies in the parallel structure are diagnosed by comparing the estimated capacity value at the second time with the threshold capacity value.

11. The battery diagnostic method according to claim 10, wherein, The charging / discharging data includes a voltage time series and a current time series. The voltage time series indicates the change of voltage across the battery over time, and the current time series indicates the change of charging / discharging current flowing through the battery over time.

12. The battery diagnostic method according to claim 10, wherein, The step of determining an estimated capacity value indicating the full-charge capacity of the battery includes the following steps: The cumulative current value and state of charge (SOC) change value of the battery are determined by inputting the charge / discharge data into the capacity estimation model; and The estimated capacity value is determined based on the ratio of the accumulated current value to the change in SOC.

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