Battery diagnostic devices, battery packs, electric vehicles, and battery diagnostic methods

Abstract

The battery diagnostic device includes: a battery monitor for detecting the voltage of each of a plurality of battery cells included in a battery module; and control circuitry for determining a latest value of a first voltage deviation, representing the difference between the voltage behavior of each battery cell from the start time of a dormant event to its relaxation time and the average voltage behavior of the plurality of battery cells. For each battery cell, the control circuitry determines a latest value of a second voltage deviation by applying a smoothing algorithm to the latest value of the first voltage deviation, determines a latest value of a third voltage deviation, representing the difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation, determines a latest value of a fourth voltage deviation, representing the difference between the latest value of the third voltage deviation and a previous value of the third voltage deviation, determines a latest value of a threshold deviation by using a time series dispersion of the fourth voltage deviation having a predetermined size, and compares the latest value of the third voltage deviation with the latest value of the threshold deviation to determine whether a micro-short circuit exists in the corresponding battery cell.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2021-0136165, filed with the Korean Intellectual Property Office on October 13, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to performing micro-short circuit diagnosis in each battery cell based on the voltage behavior of the battery cell in an idle state. Background Technology

[0003] Recently, the demand for portable electronic products such as laptops, cameras and mobile phones has increased rapidly. With the development of electric vehicles, energy storage batteries, robots and satellites, much research has been conducted on high-performance rechargeable batteries.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have almost no memory effect. Therefore, compared with nickel-based batteries, lithium batteries are receiving increasing attention due to their advantages of convenient charging, very low self-discharge rate, and high energy density.

[0005] To meet the high voltage and high capacity requirements of applications such as electric vehicles, battery systems, including battery series structures (e.g., battery packs), are common.

[0006] In a battery system, a failure in a single battery cell can negatively impact the overall performance and safety of the system. Therefore, accurately detecting failures in individual battery cells is crucial for battery system management.

[0007] Among the various types of battery cell failures, micro-short circuits (also known as internal short circuits) are a typical type of defect that directly or indirectly affects fire. Micro-short circuits are caused by side reactions (e.g., lithium metal deposition) and / or the infiltration of impurities into the battery cell.

[0008] Micro-short circuit detection typically involves comparing a reference value with the internal resistance of a battery cell, which is continuously monitored during charging and discharging. However, internal resistance estimation requires not only voltage but also the detection current value for each battery cell, and the internal resistance is highly dependent on various internal and external conditions, thus resulting in low accuracy. Summary of the Invention

[0009] Technical issues

[0010] This disclosure aims to address the aforementioned problems. Therefore, this disclosure aims to provide an apparatus and method for detecting micro-short circuits that are strongly correlated with voltage behavior by monitoring the voltage behavior trends of battery cells with recurring idle events during idle periods.

[0011] These and other objects and advantages of this disclosure will be understood from the following description and will become apparent from the 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.

[0012] Technical solution

[0013] A battery diagnostic apparatus according to one aspect of this disclosure includes: a battery monitor configured to detect the voltage of each of a plurality of battery cells included in a battery module; and a control circuit configured to determine a latest value of a first voltage deviation representing the difference between the voltage behavior of each battery cell and the average voltage behavior of the plurality of battery cells during a relaxation period from the start time of an idle event in which the battery module transitions from charging to idle. When the total number of idle events occurs is equal to or greater than a reference number, the control circuit is configured, for each battery cell, to determine a latest value of a second voltage deviation corresponding to the latest value of the first voltage deviation by applying a smoothing algorithm to the latest value of the first voltage deviation. The control circuit is configured, for each battery cell, to determine a latest value of a third voltage deviation representing the difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation. The control circuit is configured, for each battery cell, to determine a latest value of a fourth voltage deviation representing the difference between the latest value of the third voltage deviation and a previous value of the third voltage deviation. The control circuit is configured, for each battery cell, to determine a latest value of a threshold deviation using the time series discreteness of the fourth voltage deviation having a predetermined size. The control circuit is configured to determine whether a battery cell has a micro-short circuit by comparing the latest value of the third voltage deviation with the latest value of the threshold deviation for each battery cell.

[0014] The voltage behavior of each battery cell can be represented by the average value of the voltage of the corresponding battery cell detected sequentially a predetermined number of times during a relaxation period starting from the start time of the idle event.

[0015] The smoothing algorithm can be a moving average filter. The number of references can be equal to or greater than the size of the moving average filter.

[0016] Dispersion can be the standard deviation.

[0017] The control circuit can be configured, for each battery cell, to determine the latest value of the threshold deviation by multiplying the dispersion by a predetermined marginal constant.

[0018] The control circuit can be configured to, for each battery cell: when the latest value of the third voltage deviation is equal to or less than the latest value of the threshold deviation, increase the anomalous factor associated with the corresponding battery cell by a first value, and when the anomalous factor associated with the corresponding battery cell reaches the threshold, determine that the corresponding battery cell has the micro-short circuit.

[0019] The control circuit can be configured to, for each battery cell, reduce the anomalous factor associated with the corresponding battery cell by a second value when the latest value of the third voltage deviation is greater than the latest value of the threshold deviation.

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

[0021] According to another aspect of this disclosure, an electric vehicle includes a battery pack.

[0022] According to another aspect of the present disclosure, the battery diagnostic method includes the following steps: determining a latest value of a first voltage deviation, representing the difference between the voltage behavior of each battery cell and the average voltage behavior of the plurality of battery cells, during a relaxation period from the start time of an idle event in which a battery module including the plurality of battery cells transitions from charging to idle. When the total number of idle events is equal to or greater than a reference number, the battery diagnostic method further includes the following steps, for each battery cell: determining a latest value of a second voltage deviation corresponding to the latest value of the first voltage deviation by applying a smoothing algorithm to the latest value of the first voltage deviation; determining a latest value of a fourth voltage deviation, representing the difference between the latest value of a third voltage deviation and a previous value of the third voltage deviation; determining a latest value of a threshold deviation using the dispersion of the time series of the fourth voltage deviation having a predetermined size; and determining whether the corresponding battery cell has a micro-short circuit by comparing the latest value of the third voltage deviation with the latest value of the threshold deviation.

[0023] The voltage behavior of each battery cell can be represented by the average value of the voltage of the corresponding battery cell detected sequentially a predetermined number of times during a relaxation period starting from the start time of the idle event.

[0024] The smoothing algorithm can be a moving average filter. The number of references can be equal to or greater than the size of the moving average filter.

[0025] Dispersion can be the standard deviation.

[0026] The latest value of the threshold deviation can be equal to the product of the dispersion and the predetermined marginal constant.

[0027] Beneficial effects

[0028] According to at least one embodiment of the present disclosure, a micro-short circuit strongly correlated with voltage behavior can be detected by monitoring the trend of voltage behavior of multiple battery cells with recurring idle events during idle periods. Therefore, appropriate protective measures can be taken to prevent dangerous problems (such as explosions or fires in battery cells) caused by micro-short circuits.

[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 based on the appended claims. Attached Figure Description

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

[0031] Figure 1 The diagram illustrates an electric vehicle according to this disclosure.

[0032] Figure 2 This diagram is referenced when describing an exemplary equivalent circuit of a battery cell.

[0033] Figure 3 This is a graph used to describe how the voltage of a battery cell changes over time during idle periods.

[0034] Figure 4 This is an example of a graph showing the voltage behavior of a battery cell over time under repeated idle events.

[0035] Figure 5 This is an exemplary graph showing the first voltage deviation of a battery cell over time in the case of repeated idle events.

[0036] Figure 6 This is an example of a graph showing the second voltage deviation of a battery cell over time in the case of repeated idle events.

[0037] Figure 7 This is an example of a graph showing the third voltage deviation of a battery cell over time in the case of repeated idle events.

[0038] Figure 8 This is an exemplary graph showing the fourth voltage deviation of a battery cell over time in the case of repeated idle events.

[0039] Figure 9 This is an example of a graph showing the change over time in the threshold deviation for determining the micro-short circuit of a battery cell in the case of repeated idle events.

[0040] Figure 10 and Figure 11 This is a flowchart referenced when exemplarily describing a battery diagnostic method according to an embodiment of the present disclosure. Detailed Implementation

[0041] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but should be interpreted based on their meanings and concepts corresponding to the technical solutions of the present disclosure, on the basis of allowing the inventors to appropriately define the terms to obtain the best interpretation.

[0042] Therefore, the embodiments described herein and the examples shown in the accompanying drawings are merely the most preferred 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 may have been made to them at the time of filing.

[0043] Ordinal terms such as “first” and “second” are used to distinguish one element from others among various elements, but are not intended to limit elements by terminology.

[0044] Unless the context clearly indicates otherwise, the term "comprising," when used in this specification, will be understood to specify the presence of the mentioned element, but does not exclude the presence or addition of one or more other elements. Additionally, the term "unit" as used herein refers to a processing unit having at least one function or operation, which can be implemented by hardware and software, alone or in combination.

[0045] Furthermore, throughout the specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or there can be an intermediary element.

[0046] Figure 1 The diagram illustrates an electric vehicle according to this disclosure.

[0047] 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+, 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 can be located in a charging station outside the electric vehicle 1.

[0048] The vehicle controller 2 (e.g., an electronic control unit (ECU)) is configured to send a key-on signal to the battery diagnostic device 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 diagnostic device 100 in response to the user switching the ignition button to the off position. The charger 40 can provide charging power through the charging / discharging terminals (P+, P-) of the battery pack 10 via communication with the vehicle controller 2.

[0049] The battery pack 10 includes a battery module 11, a relay 20, and a battery diagnostic device 100.

[0050] Battery module 11 includes multiple battery cells B1 to B2. N A series structure of multiple battery cells B1 to B2 (where N is a natural number greater than 2). That is, in battery module 11, multiple battery cells B1 to B2 are connected in series. N They can be connected in series. Multiple battery cells B1 to B2 N They can be manufactured with the same electrical and chemical specifications. For example, multiple battery cells B1 to B2. N Not limited to a specific type, it can include any type of rechargeable battery cell (such as a lithium-ion cell). Hereinafter, multiple battery cells B1 to B... N In the common description, the symbol 'B' is affixed. j The cell is represented by 'j' (where j is a natural number N or smaller).

[0051] The relay 20 is connected in series with the battery module 11 through the power path connecting the battery module 11 and the electrical load 30. Figure 1 A relay 20 is shown connected between the positive terminal and one of the charging / discharging terminals (P+) of the battery module 11. The on / off control of the relay 20 is performed in response to a switching signal from the battery diagnostic device 100 and / or the vehicle controller 2. The relay 20 can be a mechanical contactor that is opened / closed by the magnetic force of a coil, or a semiconductor switch such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0052] The electrical load 30 includes an inverter 31 and a motor 32. The inverter 31 is configured to convert direct current (DC) power from the battery modules 11 included in the battery pack 10 into alternating current (AC) power in response to commands from the battery diagnostic device 100 or the vehicle controller 2. The motor 32 operates using the AC power from the inverter 31. The motor 32 may include, for example, a three-phase AC motor.

[0053] The state in which the battery module 11 is charged and discharged by turning on the relay 20 can be called 'cycle state (or load state)'.

[0054] When relay 20 changes from on to off, battery module 11 changes from cyclic state to 'idle state (or no-load state, calendar state)', battery unit B j The voltage at idle time can be called 'relaxation voltage (or idle voltage, no-load voltage)'. In battery cell B... j The relaxation voltage after a sufficiently long period of time following a switch from charging or discharging to idle can converge to the open-circuit voltage (OCV). Specifically, when battery module 11 switches from charging or discharging to idle, as battery cell B... j The polarization occurring in the cell is spontaneously alleviated, cell B j The relaxation voltage changes towards OCV.

[0055] The battery diagnostic device 100 includes a battery monitor 110 and a control circuit 120. The battery diagnostic device 100 may further include a communication circuit 130. Hereinafter, it is assumed that the battery diagnostic device 100 includes a battery monitor 110, a control circuit 120, and a communication circuit 130.

[0056] The battery monitor 110 includes a voltage detector 112. The battery monitor 110 may further include a current detector 114.

[0057] Voltage detector 112 and multiple battery cells B1 to B1 included in battery module 11 N Each of the positive and negative terminals is connected and configured to detect battery cell B. j The voltage across the two ends (also known as "cell voltage") generates a voltage signal representing the detected cell voltage.

[0058] Current detector 114 is connected in series to battery module 11 via the current path between battery module 11 and inverter 31. Current detector 114 may include at least one known current sensing device (such as a shunt resistor and a Hall effect device). When multiple battery cells B1~B N like Figure 1 When connected in series as shown, multiple battery cells B1 to B2 N The same charging / discharging current flows through them.

[0059] Figure 1 The shunt resistor used as current detector 114 is shown. In this case, current detector 114 can output a current signal indicating the direction and magnitude of the charging / discharging current to control circuit 120 based on the voltage across the shunt resistor according to Ohm's law.

[0060] The control circuit 120 can be operatively connected to the relay 20, the battery monitor 110, and the communication circuit 130. Ooperative connection means a direct / indirect connection to send and receive signals in one or both directions.

[0061] The control circuit 120 may be referred to as a "battery controller" and may be implemented in 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.

[0062] Control circuitry 120 can collect voltage and / or current signals from battery monitor 110. For example, control circuitry 120 can use an analog-to-digital converter (ADC) provided therein to convert the analog signals collected from battery monitor 110 into digital values ​​and record them. Alternatively, battery monitor 110 itself can send the result of the analog-to-digital conversion to control circuitry 120.

[0063] Memory 121 may include at least one type of storage medium, such as 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). Memory 121 may store data and programs required for the calculation operations of control circuit 120. Memory 121 may store data representing the results of the calculation operations performed by control circuit 120. Memory 121 may store data used for detecting battery cell B. j The micro-short circuit provides a given function, logic, and algorithm. Memory 121 can be integrated into control circuitry 120.

[0064] Control circuit 120 can activate relay 20 in response to a key activation signal from vehicle controller 2. Control circuit 120 can deactivate relay 20 in response to a key deactivation signal from vehicle controller 2. The key activation signal is a signal requesting a switch from idle to cycle. The key deactivation signal is a signal requesting a switch from cycle to idle. Alternatively, vehicle controller 2 can replace control circuit 120 in controlling the activation / deactivation of relay 20.

[0065] Communication circuit 130 is configured to support wired or wireless communication between control circuit 120 and vehicle controller 2. Wired communication may be, for example, Controller Area Network (CAN) communication, while wireless communication may be, for example, Zigbee or Bluetooth communication. The communication protocol is not limited to a specific type and may include any communication protocol that supports wired / wireless communication between control circuit 120 and vehicle controller 2. Communication circuit 130 may include output devices (e.g., a display, a speaker) to provide information received from control circuit 120 and / or vehicle controller 2 in a format recognizable by the user (driver).

[0066] Figure 2 This diagram is used in describing an exemplary equivalent circuit of a battery cell. In this specification, a normal battery cell refers to a battery cell without micro-short circuits, while an abnormal battery cell refers to a battery cell with micro-short circuits.

[0067] Reference Figure 2 The equivalent circuit 200 shown can be represented by a normal battery cell as a DC power supply V. DC The internal resistor R0 and the resistor-capacitor (RC) are connected in series with R1 and C. In contrast, an abnormal battery cell can be equivalent to a series circuit corresponding to the series circuit of a normal battery cell, further including an additional resistor R connected between the two terminals + and -. ISC Additional resistor R ISC Used as leakage current I ISC The path. For reference, DC power supply V DC The voltage is that of battery cell B j OCV, battery cell B j The unit voltage is DC power supply V. DC The total voltage of the series circuit of internal resistors R0 and RC with respect to R1 and C. When the charging / discharging current is zero (0A) and the voltage across RC with respect to R1 and C is zero (0V), the relaxation voltage is equal to OCV.

[0068] During the charging process of the faulty battery cell, some charging power is not stored in the faulty battery cell, but is instead released as leakage current I. ISC It was used up. Furthermore, during the discharge process of the abnormal battery cell, some discharge power was not supplied to the electrical load 30, but instead was used as leakage current I. ISC Used. Resistor R ISC A decrease in resistance indicates that the micro-short circuit has become more severe, and as the micro-short circuit becomes more severe, the leakage current I increases. ISC Power consumption may increase. Therefore, during charging, the voltage rise of an abnormal battery cell may be smaller than that of a normal battery cell. Conversely, during discharging, the voltage drop of an abnormal battery cell may be larger than that of a normal battery cell.

[0069] Furthermore, even when the battery cell is in an idle state with zero charging / discharging current, the energy stored in the abnormal battery cell can be used as a leakage current I. ISC It is used up. Therefore, during idle periods, the voltage of abnormal battery cells is lower than that of normal battery cells, and the voltage of abnormal battery cells drops faster than that of normal battery cells.

[0070] Below, we will refer to Figures 3 to 5 Detailed description of the function executed by control circuit 120 for detecting multiple battery cells B1 to B2 N The operation of battery cells with micro-short circuits.

[0071] Figure 3 This is a graph used as a reference when describing the voltage change of a battery cell over time during idle periods. Figure 4 This is an exemplary graph showing the voltage behavior of a battery cell over time under repeated idle events. Figure 5 This is an exemplary graph showing the first voltage deviation of a battery cell over time under repeated resting events. Figure 4 and Figure 5 In the diagram, the horizontal axis represents the number of events x, which indicates the order in which idle events occur. Figure 4 The vertical axis represents battery cell B. j The voltage behavior of each idle event (average voltage during the relaxation period), and Figure 5 The vertical axis represents battery cell B. j The first voltage deviation for each idle event.

[0072] first, Figure 3 Multiple battery cells B1 to B1 are shown. N Any of the battery cells B j Voltage behavior during idle period. Time t A This is the start time of a specific idle event. This idle event is the transition of battery module 11 from charging to idle. Battery cell B j The unit voltage at the start time t A It had been rising continuously until the beginning time t A The charging current drops instantaneously when it becomes 0, and then converges towards the OCV. Time t B It is from the start time t A The time after the predetermined relaxation time Δt.

[0073] Battery cell B j The voltage behavior is represented from time t A By time t B During the relaxation period Δt, battery cell B is inspected sequentially a predetermined number of times.j The average voltage. The relaxation period Δt can be used to detect the battery cell B. j The voltage time interval is a predetermined multiple. For example, the relaxation period Δt could be 60 seconds, and the battery cell B... j The voltage can be detected sequentially a total of 600 times within a 0.1-second time interval. Therefore, it can be determined that from time t... A By time t B During the idle time, multiple battery cells B1 to B N The voltage behavior of each of the multiple battery cells B1 to B2. Equation 1 below is used to calculate the voltage behavior of each of the multiple battery cells B1 to B2. N Battery cell B in j Examples of functions of voltage behavior.

[0074] Equation 1

[0075]

[0076] In Equation 1, S is the total number of voltage detections during the relaxation period Δt (e.g., 600 times), and V j [i][x] represents the battery cell B at the i-th detection time during the idle period, based on the number of idle events x. j The voltage, and V j_AV [x] represents the number of idle events x, and the number of battery cells B detected S times during the relaxation period Δt. j The average voltage.

[0077] Control circuit 120 monitors battery cell B during the idle period each time an idle event occurs (i.e., each time the event number x increases by 1). j The voltage behavior. Therefore, as Figure 4 As shown, memory 121 records multiple battery cells B1 to B2 that represent repeated idle events. N Multiple voltage behaviors V 1_AV [x]~V N_AV [x] is a time series that changes over time.

[0078] Control circuit 120 determines the battery cell B when each idle event occurs. j The latest value of the first voltage deviation. Battery cell B j The first voltage deviation indicates that battery cell B j The voltage behavior of multiple battery cells B1 to B N The difference between the average voltage behavior and the average voltage behavior. Equation 2 below is used to calculate battery cell B. j An example of a function of the first voltage deviation.

[0079] Equation 2

[0080]

[0081] In equation 2, V M [x] represents multiple battery cells B1 to B1. N The average voltage behavior corresponding to the number of idle events x, V j_D1 [x] is battery cell B j This corresponds to the first voltage deviation of the idle event number x. In other words, each time the event number x increases by 1, the voltage deviation can be calculated relative to multiple battery cells B1 to B2. N Related V 1_D1 [x] to V N_D1 [x]. Therefore, as Figure 5 As shown, memory 121 records the data representing the repetition of idle events across multiple battery cells B1 to B2. N Multiple first voltage deviations V 1_D1 [x]~V N_D1 The time series that changes over time in [x]. Meanwhile, in Figure 5 In the multiple first voltage deviation curves, the specific curve marked by the thick solid line shows that the first voltage deviation decreases faster than other curves as the number of events x increases.

[0082] Below, we will refer to Figures 6 to 9 The process for detecting micro-short circuits is additionally performed by control circuit 120. Figures 6 to 9 The relevant process can be executed when the following condition is met: the total number of idle events (i.e., the number of most recently occurring idle events x) is equal to or greater than the reference number. Furthermore, for ease of description, Figures 6 to 9 The curve shown is Figure 5 The single curve marked with a thick solid line among the multiple first voltage deviation curves shown is related to the abnormal battery cell.

[0083] Figure 6 This is an exemplary graph showing the second voltage deviation of a battery cell over time under repeated idle events. Figure 7 This is an exemplary graph showing the third voltage deviation of a battery cell over time under repeated idle events. Figure 8 This is an exemplary graph showing the fourth voltage deviation of the battery cell over time under repeated idle events, and Figure 9 This is an exemplary graph showing the change over time of the threshold deviation used for micro-short circuit determination in the case of repeated idle events for the battery cell. For ease of description, Figures 6 to 9 Only a single curve showing the second voltage deviation over time, which is associated with the first voltage deviation of the abnormal battery cell, is shown.

[0084] Reference Figure 6The control circuit 120 can control battery cell B j The latest value of the first voltage deviation is used to determine the battery cell B corresponding to the latest value of the first voltage deviation using a smoothing algorithm. j The latest value of the second voltage deviation. The moving average filter is an example of a smoothing algorithm. Equation 3 below is used to calculate battery cell B. j An example of a moving average filter for the second voltage deviation.

[0085] Equation 3

[0086]

[0087] In Equation 3, W (a natural number of 2 or greater) is the size of the moving average filter, and V j_D2 [x] is battery cell B j The second voltage deviation, V, corresponds to the number of idle events x. j_D2 [x-1] is battery cell B j The second voltage deviation corresponds to the number of idle events x-1. Battery cell B j The latest value of the second voltage deviation can be represented by the first voltage deviation V associated with past (W-1) idle events. j_D1 [x-W+1]~V j_D1 [x-1] is the latest value of V, the first voltage deviation corresponding to the current idle event. j_D1 The correction result for [x]. The number of events x increases by 1 each time, corresponding to multiple battery cells B1 to B2. N Related V 1_D2 [x] to V N_D2 [x] can then be recalculated. Therefore, this represents multiple battery cells B1 to B2 that have repeated idle events. N Multiple second voltage deviations V 1_D2 [x] to V N_D2 The time series of [x] changing over time (i.e., the relationship between the number of events and the second voltage deviation) is recorded in memory 121. The smoothing algorithm can be replaced by any other algorithm other than Equation 3 (e.g., a double exponential smoothing filter).

[0088] Reference Figure 7 The control circuit 120 determines a latest value of a third voltage deviation, representing the difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation. Equation 4 below shows the relationship between the first voltage deviation, the second voltage deviation, and the third voltage deviation.

[0089] Equation 4

[0090] V j_D3 [x] = V j_D1[x]-V j_D2 [x]

[0091] In equation 4, V j_D3 [x] is battery cell B j The third voltage deviation corresponding to the number of idle events x. Battery cell B j The third voltage deviation represents battery cell B j The trend of deepening short circuits in the micro-cells. Each time the number of events x increases by 1, it can be calculated that the short circuits affect multiple battery cells B1 to B2. N Related V 1_D3 [x] to V N_D3 [x]. Therefore, this represents multiple battery cells B1 to B2 that have repeated idle events. N Multiple third voltage deviations V 1_D3 [x] to V N_D3 The time series of [x] changing over time (i.e., the relationship between the number of events and the third voltage deviation) is recorded in memory 121.

[0092] Reference Figure 8 The control circuit 120 determines the latest value of the fourth voltage deviation, which represents the difference between the latest value of the third voltage deviation and the previous value of the third voltage deviation. Battery cell B j The fourth voltage deviation indicates that the battery cell B j The trend of deepening short circuits in the medium and micro-short circuits fluctuates. Equation 5 below shows the relationship between the third voltage deviation and the fourth voltage deviation.

[0093] Equation 5

[0094] V j_D4 [x] = V j_D3 [x]-V j_D3 [x-1]

[0095] In equation 5, V j_D4 [x] is battery cell B j The fourth voltage deviation corresponds to the number of events x in the idle event. When x is the current number of events, V j_D3 [x] is the latest value of the third voltage deviation, V j_D3 [x-1] is the previous value of the third voltage deviation. Each time the event number x increases by 1, the value can be calculated relative to multiple battery cells B1 to B2. N Related V 1_D4 [x] to V N_D4 [x]. Therefore, this represents multiple battery cells B1 to B2 that have repeated idle events. N Multiple fourth voltage deviations V 1_D4 [x] to V N_D4The time series of [x] changing over time (i.e., the relationship between the number of events and the fourth voltage deviation) is recorded in memory 121.

[0096] Reference Figure 9 The control circuit 120 uses the discreteness of the time series of a fourth voltage deviation with a predetermined size (2 or a natural number greater) to determine the battery cell B. j The latest value of the threshold deviation. Equation 6 below is used to calculate the threshold deviation as battery cell B. j An example of a function of the discrete standard deviation of the time series of the fourth voltage deviation.

[0097] Equation 6

[0098]

[0099] In equation 6, σ j [x] is battery cell B j The standard deviation of the time series (of magnitude y) of the fourth voltage deviation, V j_D4_AV It is the average value of the time series (of size y) of the fourth voltage deviation. σ j [x] corresponds to the number of idle events, x.

[0100] Control circuit 120 can determine the battery cell B to be detected. j The latest value of the threshold deviation V of the micro short circuit j_Th [x] is equal to the dispersion σ j The value obtained by multiplying [x] by a predetermined marginal constant. For example, V j_Th [x] = σ j [x]×QQ is the marginal constant. Therefore, each time the number of events x increases by 1, the value of the event can be calculated relative to multiple battery cells B1 to B2. N Related V 1_Th [x] to V N_Th [x]. Therefore, this represents multiple battery cells B1 to B2 that have repeated idle events. N Multiple threshold deviations V 1_Th [x] to V N_Th The time series of [x] over time (i.e., the relationship between the number of events and the threshold deviation) is recorded in memory 121. Figure 9 The curves show the relationship between abnormal battery cells when y and Q are 100 and -15, respectively (see...). Figure 5 The time series of threshold deviations associated with the thick line.

[0101] Each time the event number x increases by 1, the control circuit 120 can control the battery cell B. j The latest value of the associated third voltage deviation V j_D3The latest value of V, the deviation of [x] from the threshold. j_Th [x] Compare to determine the corresponding battery cell B j Does it have a micro short circuit?

[0102] Each time the number of events x increases by 1, when V j_D3 [x]≤V j_Th When [x], the control circuit 120 can add a representation of battery cell B. j An abnormal factor that may cause a micro-short circuit is present in the battery cell; otherwise, the control circuit 120 can reduce the abnormal factor. For example, the abnormal factor can be increased by a first value (e.g., 10) from a previous value, or increased by a first percentage (e.g., 10%) of the previous value. The abnormal factor can be decreased by a second value (e.g., 1) from a previous value, or decreased by a second percentage (e.g., 2%) of the previous value. The control circuit 120 can respond to the interaction with battery cell B. j If the associated anomaly factor is equal to or greater than a threshold (e.g., 100), battery cell B is identified. j There is a micro-short circuit. This is in response to the condition that V is continuously satisfied as the number of events x increases to a predetermined value (e.g., 10). j_D3 [x]>V j_Th Under the condition of [x], the control circuit 120 can connect with battery cell B. j The associated anomaly factor is reset to its initial value (e.g., 0). The initial value is the lower bound of the anomaly factor.

[0103] Those skilled in the art will readily understand that when Q is positive (e.g., 15) rather than negative (e.g., -15), the condition for increasing the outlier will be reversed, i.e., V j_D3 [x]≥V j_Th [x].

[0104] Figure 10 and Figure 11 This is a flowchart referenced when exemplarily describing a battery diagnostic method according to an embodiment of the present disclosure. Figure 10 and 11 The method can begin each time an idle event occurs, when the battery module 11 transitions from charging to idle. For reference, a value 1 greater than the previous event number can be assigned to the event number x of the newly generated idle event.

[0105] Reference Figures 1 to 11 In step S1010, the control circuit 120 targets multiple battery cells B1 to B2. N Each of them represents battery cell B. j Voltage behavior V j_AV [x] and multiple battery cells B1 to B N Average voltage behavior V M[x] The latest value of the first voltage deviation V during the relaxation period Δt from the start time of the idle event. j_D1 [x](see Equations 1 and 2). V j_D1 [x] can be recorded in memory 121.

[0106] In step S1020, the control circuit 120 determines whether the total number of idle events that have occurred is equal to or greater than a reference number. If the value of step S1020 is "yes", step S1030 is executed. The total number can represent the maximum value among the number of events assigned to the idle events that have occurred so far.

[0107] In step S1030, the control circuit 120 targets multiple battery cells B1 to B2. N For each of them, a smoothing algorithm is applied to the latest value of the first voltage deviation to determine the latest value V corresponding to the first voltage deviation. j_D1 The latest value of the second voltage deviation of [x] V j_D2 [x](see Equation 3). The latest value of the second voltage deviation, V. j_D2 [x] can be the latest value of the first voltage deviation, V. j_D1 [x] and the previous value V of the second voltage deviation j_D2 The weighted average of [x-1]. V j_D2 [x] can be recorded in memory 121.

[0108] In step S1040, the control circuit 120 targets multiple battery cells B1 to B2. N For each of the values, determine the latest value V representing the first voltage deviation. j_D1 [x] and the latest value of the second voltage deviation V j_D2 The latest value of the third voltage deviation V of the difference between [x] j_D3 [x](see Equation 4). V j_D3 [x] can be recorded in memory 121.

[0109] In step S1050, the control circuit 120 targets multiple battery cells B1 to B2. N For each of them, determine the latest value V representing the third voltage deviation. j_D3 [x] and the previous value V of the third voltage deviation j_D3 The latest value of the fourth voltage deviation V of the difference between [x-1] j_D4 [x](see Equation 5). V j_D4 [x] can be recorded in memory 121.

[0110] In step S1060, the control circuit 120 targets multiple battery cells B1 to B2. NEach of them utilizes a time series V with a fourth voltage deviation of a predetermined size y. j_D4 [x-y+1]~V j_D4 The dispersion of [x] (e.g., standard deviation σ) j [x]) to determine the latest value V of the threshold deviation j_Th [x](see Equation 6).

[0111] In step S1070, the control circuit 120 targets multiple battery cells B1 to B2. N Each of them is compared with the latest value V of the third voltage deviation. j_D3 The latest value of [x] and threshold deviation V j_Th [x] determines whether V is satisfied. j_D3 [x]≤V j_Th The condition of [x]. V j_D3 [x]≤V j_Th [x] represents battery cell B j A micro-short circuit may occur. If the value of step S1070 is "yes", proceed to step S1082. If the value of step S1070 is "no", proceed to step S1084.

[0112] In step S1082, the control circuit 120 will communicate with multiple battery cells B1 to B2. N In satisfying V j_D3 [x]≤V j_Th Battery cell B under condition [x] j The associated anomalous factor increases by the first value.

[0113] In step S1084, the control circuit 120 will communicate with the multiple battery cells B1 to B2. N The middle does not satisfy V j_D3 [x]≤V j_Th Battery cell B under condition [x] j The associated anomalous factors reduced the second value.

[0114] In step S1086, the control circuit 120 determines and satisfies V j_D3 [x]≤V j_Th Battery cell B under condition [x] j Is the associated anomaly factor equal to or greater than the threshold? The value of step S1086 is "Yes," indicating that in battery cell B... j A micro short circuit was detected. When the value of step S1086 is "yes", step S1090 can be executed.

[0115] In step S1090, the control circuit 120 performs at least one protection operation. This protection operation may include generating a diagnostic message to notify battery cell B associated with a threshold or more abnormal factors. jThe diagnostic information includes the identification number and / or location. This diagnostic information can be transmitted to the vehicle controller 2 and / or the vehicle user via communication circuit 130. Protection operations may include the shutdown control of relay 20.

[0116] The embodiments of the present disclosure described above are not only implemented by apparatus and methods, but also by a program that performs functions corresponding to the configuration of the embodiments of the present disclosure or a recording medium on which the program is recorded, and such implementation can be easily implemented by those skilled in the art based on the disclosure of the above embodiments.

[0117] 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 variations can be made to it within the technical aspects of this disclosure and within the equivalent scope of the appended claims.

[0118] Additionally, since those skilled in the art can make many substitutions, modifications and variations to the present disclosure described above without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the above embodiments and drawings, but can selectively combine some or all of the embodiments to allow for various modifications.

[0119] (Description of reference numerals in the attached diagram)

[0120] 1: Electric vehicle 2: Vehicle controller

[0121] 10: Battery pack 11: Battery module

[0122] B: Battery unit

[0123] 100: Battery diagnostic device; 110: Battery monitor

[0124] 120: Control circuit; 130: Communication circuit

Claims

1. A battery diagnostic device, the battery diagnostic device comprising: A battery monitor configured to detect the voltage of each of a plurality of battery cells included in a battery module; as well as A control circuit configured to determine a latest value of a first voltage deviation representing the difference between the voltage behavior of each battery cell and the average voltage behavior of the plurality of battery cells during a relaxation period from the start time of an idle event in which the battery module transitions from charging to idle. Wherein, when the total number of idle events is equal to or greater than the reference number, The control circuit is configured, for each battery cell: The latest value of the second voltage deviation corresponding to the latest value of the first voltage deviation is determined by applying a smoothing algorithm to the latest value of the first voltage deviation. Determine the latest value of the third voltage deviation, which represents the difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation; Determine the latest value of the fourth voltage deviation, which represents the difference between the latest value of the third voltage deviation and the previous value of the third voltage deviation; The latest value of the threshold deviation is determined using the discreteness of the time series of the fourth voltage deviation, which has a predetermined size; and Whether the corresponding battery cell has a micro-short circuit is determined by comparing the latest value of the third voltage deviation with the latest value of the threshold deviation.

2. The battery diagnostic device according to claim 1, wherein, The voltage behavior of each battery cell represents the average voltage of the corresponding battery cell measured sequentially a predetermined number of times during a relaxation period starting from the start time of the idle event.

3. The battery diagnostic device according to claim 1, wherein, The smoothing algorithm is a moving average filter, and Wherein, the reference number is equal to or greater than the size of the moving average filter.

4. The battery diagnostic device according to claim 1, wherein, The dispersion is the standard deviation.

5. The battery diagnostic device according to claim 1, wherein, The control circuit is configured, for each battery cell, to determine the latest value of the threshold deviation by multiplying the dispersion by a predetermined marginal constant.

6. The battery diagnostic device according to claim 1, wherein, The control circuit is configured, for each battery cell: When the latest value of the third voltage deviation is equal to or less than the latest value of the threshold deviation, the anomaly factor associated with the corresponding battery cell is increased by a first value, and When the abnormal factor associated with the corresponding battery cell reaches a threshold, it is determined that the corresponding battery cell has the micro short circuit.

7. The battery diagnostic device according to claim 6, wherein, The control circuit is configured to, for each battery cell, reduce the anomalous factor associated with the corresponding battery cell by a second value when the latest value of the third voltage deviation is greater than the latest value of the threshold deviation.

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, the battery diagnostic method comprising the following steps: The latest value of the first voltage deviation, representing the difference between the voltage behavior of each battery cell and the average voltage behavior of the multiple battery cells, is determined during a relaxation period starting from the start time of the idle event in which the battery module comprising multiple battery cells transitions from charging to idle. Wherein, when the total number of idle events is equal to or greater than the reference number, The battery diagnostic method further includes the following steps for each battery cell: The latest value of the second voltage deviation corresponding to the latest value of the first voltage deviation is determined by applying a smoothing algorithm to the latest value of the first voltage deviation. Determine the latest value of the third voltage deviation, which represents the difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation; Determine the latest value of the fourth voltage deviation, which represents the difference between the latest value of the third voltage deviation and the previous value of the third voltage deviation; The latest value of the threshold deviation is determined using the discreteness of the time series of the fourth voltage deviation, which has a predetermined size; and Whether the corresponding battery cell has a micro-short circuit is determined by comparing the latest value of the third voltage deviation with the latest value of the threshold deviation.

11. The battery diagnostic method according to claim 10, wherein, The voltage behavior of each battery cell represents the average voltage of the corresponding battery cell measured sequentially a predetermined number of times during a relaxation period starting from the start time of the idle event.

12. The battery diagnostic method according to claim 10, wherein, The smoothing algorithm is a moving average filter, and Wherein, the reference number is equal to or greater than the size of the moving average filter.

13. The battery diagnostic method according to claim 10, wherein, The dispersion is the standard deviation.

14. The battery diagnostic method according to claim 10, wherein, The latest value of the threshold deviation is equal to the product of the dispersion and the predetermined marginal constant.

15. The battery diagnostic method according to claim 10, further comprising the step of, for each battery cell: When the latest value of the third voltage deviation is equal to or less than the latest value of the threshold deviation, the anomaly factor associated with the corresponding battery cell is increased by a first value; and When the abnormal factor associated with the corresponding battery cell reaches a threshold, it is determined that the corresponding battery cell has the micro short circuit.

16. The battery diagnostic method according to claim 10, further comprising the step of, for each battery cell: when the latest value of the third voltage deviation is greater than the latest value of the threshold deviation, reducing the abnormal factor associated with the corresponding battery cell by a second value.

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