Battery diagnostic device and method

Abstract

A battery diagnostic device according to one embodiment of the present invention may include a voltage measurement unit that measures the voltage of each battery cell during a preset time period; a voltage change amount calculation unit that calculates an individual voltage change amount of each battery cell during the preset time period; an average voltage change amount calculation unit that calculates an average voltage change amount of a plurality of battery cells during the preset time period; and an abnormality detection unit that determines that a voltage abnormality has occurred in a battery cell when a difference between the individual voltage change amount and the average voltage change amount is greater than a threshold value for any of the battery cells.

Description

[Technical field]

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2019-0113169, filed on September 11, 2019, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery diagnostic device and method, and more particularly to a device and method for detecting a sudden drop in voltage during charging and discharging of a battery. [Background technology]

[0003] Recently, research and development into secondary batteries has been actively conducted. Here, secondary batteries are batteries that can be charged and discharged, and include conventional Ni / Cd batteries, Ni / MH batteries, and the latest lithium-ion batteries. Among secondary batteries, lithium-ion batteries have the advantage of having a much higher energy density than conventional Ni / Cd batteries, Ni / MH batteries, and the like. Lithium-ion batteries can also be manufactured to be small and lightweight, and are therefore used as power sources for mobile devices. The range of use of lithium-ion batteries has also been expanded to include power sources for electric vehicles, and they are attracting attention as a next-generation energy storage medium.

[0004] In addition, the secondary battery is generally used as a battery pack including a battery module in which a plurality of battery cells are connected in series and / or parallel, and the state and operation of the battery pack are managed and controlled by a battery management system.

[0005] When an abnormality such as an insulation abnormality in the battery pack or an internal short circuit in the battery cell occurs, the cell voltage of the battery module may suddenly drop. In this case, in the past, a method was used to detect and diagnose the voltage drop by using the voltage difference (slope) from the previous time in a state where no current flows (Rest), so a separate current sensor was always required to determine the state where no current flows. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a battery diagnostic device that can detect abnormalities caused by a sudden drop in battery voltage not only in a rest state in which no battery voltage flows but also during charging and discharging of the battery by diagnosing voltage abnormalities in a battery cell by utilizing the amount of voltage change in the battery cell without using a separate current sensor. [Means for solving the problem]

[0007] A battery diagnosis device according to one embodiment of the present invention may include a voltage measurement unit that measures the voltage of each battery cell during a preset time, a voltage change calculation unit that calculates an individual voltage change of each battery cell during the preset time, an average voltage change calculation unit that calculates an average voltage change of a plurality of battery cells during the preset time, and an abnormality detection unit that determines that a voltage abnormality has occurred in a battery cell if a difference between the individual voltage change and the average voltage change is greater than a threshold value.

[0008] The voltage change amount calculation unit of the battery diagnostic device according to one embodiment of the present invention can calculate the amount of voltage change of each of the battery cells while the battery cells are being charged or discharged.

[0009] The voltage change amount calculation unit of the battery diagnostic device according to one embodiment of the present invention can calculate the voltage change amount of the battery cell in a state (rest) in which no current flows through the battery cell.

[0010] The threshold value of the battery diagnostic device according to one embodiment of the present invention can be set according to specifications unique to the manufacturer of the battery cells. The threshold value of the battery diagnostic device according to one embodiment of the present invention can be set according to specifications unique to the manufacturer of the voltage measurement unit.

[0011] The voltage change amount calculation unit of the battery diagnosis device according to one embodiment of the present invention can calculate the voltage change amount of each of the battery cells in a region where the SOC (State of Charge) of the battery cell is equal to or greater than a preset reference value. The preset reference value of the battery diagnostic device according to an embodiment of the present invention may be set according to the type of the battery cell.

[0012] A battery diagnosis method according to one embodiment of the present invention may include the steps of measuring the voltage of each battery cell for a preset time period, calculating an individual voltage change amount of each battery cell for the preset time period, calculating an average voltage change amount of a plurality of battery cells for the preset time period, and, if there is a battery cell for which the difference between the individual voltage change amount and the average voltage change amount is greater than a threshold value, determining that a voltage abnormality has occurred in that battery cell. Effect of the Invention

[0013] According to the battery diagnostic device of the present invention, by diagnosing voltage abnormalities in a battery cell by utilizing the amount of voltage change in the battery cell without using a separate current sensor, it is possible to detect abnormalities caused by a sudden drop in battery voltage not only in a resting state where no battery voltage is flowing, but also during charging and discharging of the battery. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing a configuration of a typical battery control system. [Diagram 2] 1 is a block diagram showing a configuration of a battery diagnosis device according to an embodiment of the present invention; [Diagram 3] 11 is a diagram showing a diagnosis experiment of a defective cell performed using a battery diagnosis device according to an embodiment of the present invention when the battery is being charged. FIG. [Figure 4] FIG. 13 is a diagram showing a diagnosis experiment of a defective cell conducted by a battery diagnosis device according to an embodiment of the present invention in a resting state of the battery. [Diagram 5]3 is a flowchart showing a battery diagnosis method according to one embodiment of the present invention. [Figure 6] FIG. 1 is a diagram illustrating a hardware configuration according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this document, the same reference numerals are used to refer to the same components in the drawings, and duplicated descriptions of the same components will be omitted.

[0016] For the various embodiments of the present invention disclosed in this document, specific structural and functional descriptions are merely exemplified for purposes of describing the embodiments of the present invention, and the various embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in this document.

[0017] The terms "first," "second," "first," or "second" used in the various embodiments may modify various components regardless of order and / or importance and do not limit the components. For example, a first component may be named a second component, and similarly, the second component may be renamed to the first component without departing from the scope of the invention.

[0018] The terms used in this document are merely used to describe a particular embodiment and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless otherwise clearly indicated in the context.

[0019] All terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art of the present invention. Terms defined in commonly used dictionaries may be interpreted as having the same or similar meaning as they have in the context of the relevant art, and unless expressly defined in this document, they are not interpreted in an ideal or overly formal sense. In some cases, even terms defined in this document should not be interpreted to exclude embodiments of the present invention.

[0020] FIG. 1 is a block diagram showing the configuration of a typical battery control system. Specifically, FIG. 1 is a schematic diagram showing a battery control system including a battery pack 1 according to one embodiment of the present invention and a host controller 2 included in a host system.

[0021] As shown in FIG. 1, the battery pack 1 includes a chargeable and dischargeable battery module 10 consisting of one or more battery cells, a switching unit 14 connected in series to the + terminal side or the - terminal side of the battery module 10 for controlling the flow of charge and discharge current of the battery module 10, and a battery management system (BMS) 20 that monitors the voltage, current, temperature, etc. of the battery pack 1 and controls and manages it to prevent overcharging and over-discharging, etc.

[0022] Here, the switching unit 14 is a semiconductor switching element for controlling the flow of current for charging or discharging the battery module 10, and may be, for example, at least one MOSFET.

[0023] Also, the BMS 20 can measure or calculate the voltage and current of the gate, source, drain, etc. of the semiconductor switching element in order to monitor the voltage, current, temperature, etc. of the battery pack 1, and can measure the current, voltage, temperature, etc. of the battery pack using a sensor 12 provided adjacent to the semiconductor switching element 14. The BMS 20 is an interface that receives input of measured values ​​of the various parameters described above, and can include a plurality of terminals, and circuits that are connected to these terminals and process the input values.

[0024] In addition, the BMS 20 can also control the ON / OFF of the switching elements 14, for example, MOSFETs, and is connected to the battery modules 10 to monitor the status of the battery modules 10.

[0025] The upper controller 2 can transmit a control signal for the battery module to the BMS 20. As a result, the operation of the BMS 20 can be controlled based on the signal applied from the upper controller. The battery cell of the present invention may be included in a battery pack used in an ESS (Energy Storage System) or a vehicle. However, the use is not limited to this.

[0026] Such a configuration of the battery pack 1 and the BMS 20 are well known, and therefore a more detailed description thereof will be omitted. FIG. 2 is a block diagram showing the configuration of a battery diagnostic device according to one embodiment of the present invention.

[0027] Referring to FIG. 2, a battery diagnostic device 200 according to an embodiment of the present invention may include a voltage measuring unit 210, a voltage change amount calculating unit 220, an average voltage change amount calculating unit 230, and an abnormality detecting unit 240.

[0028] The voltage measurement unit 210 may measure the voltage of each battery cell for a preset time period. For example, the voltage measurement unit 210 may be a measurement circuit included in the above-mentioned battery management system (BMS).

[0029] The voltage change amount calculation unit 220 can calculate the individual voltage change amount of each battery cell measured by the voltage measurement unit 210 during a preset time. For example, when the voltage of the battery cell is measured at two-second intervals in the voltage measurement unit 210, the voltage change amount calculation unit 220 can calculate the individual voltage change amount of each battery cell during the two-second intervals. However, this is merely an example, and the time interval can be arbitrarily set by the user.

[0030] In particular, the voltage change amount calculation unit 220 can calculate the voltage change amount of each battery cell not only in a state (rest) where no current flows through the battery cell but also during charging or discharging of the battery cell. Therefore, while a current sensor was always required to check the resting state of the battery in the past, the battery diagnosis device 200 according to one embodiment of the present invention does not need to determine the resting state of the battery via a current sensor and can detect an abnormal voltage drop only from the change amount of the battery voltage.

[0031] In addition, the voltage change amount calculation unit 220 can calculate the voltage change amount of each battery cell for a region where the SOC (State of Charge) of the battery cell is equal to or higher than a preset reference value. This is because in a region where the SOC of the battery is low, the resistance of the battery itself increases, and the deviation of the DCIR (Direct Current Internal Resistance) may become large. In this case, the reference value of the SOC can be set according to the type of the battery cell.

[0032] The average voltage change amount calculation unit 230 may calculate an average voltage change amount of a plurality of battery cells for a preset time period. For example, the average voltage change amount calculation unit 230 may calculate an average voltage change amount of all battery cells included in a specific battery pack for a preset time period.

[0033] When there is a battery cell for which the difference between the individual voltage change amount calculated by the voltage change amount calculation unit 220 and the average voltage change amount calculated by the average voltage change amount calculation unit 230 is greater than a threshold value, the abnormality detection unit 240 can determine that a voltage abnormality has occurred in that battery cell. That is, the abnormality detection unit 240 can detect whether or not there is an abnormality in the battery voltage by the following formula.

[0034] [Formula 1] ΔV cell、each -ΔV cell、average =V threshold In this case, the current SOC value > SOC threshold It is.

[0035] In this case, the threshold value of the abnormality detection unit 240 may be set according to specifications unique to a manufacturer of the battery cells and the voltage measurement unit 210. For example, the threshold value may be set in consideration of a voltage measurement error of the voltage measurement unit 210, a capacity error between battery cells that occurs during the assembly process of the battery module, and the like.

[0036] Meanwhile, although not shown in FIG. 2, the battery diagnosis device 200 according to one embodiment of the present invention may further include a memory unit (not shown) that stores an individual voltage change amount of each battery cell and an average voltage change amount of a plurality of battery cells.

[0037] In this way, with the battery diagnosis device of one embodiment of the present invention, by diagnosing voltage abnormalities in a battery cell by utilizing the amount of voltage change in the battery cell without using a separate current sensor, it is possible to detect abnormalities due to sudden drops in battery voltage not only in a resting state where no battery voltage is flowing, but also during charging and discharging of the battery.

[0038] FIG. 3 is a diagram showing a diagnosis experiment of a defective cell performed using the battery diagnosis device according to one embodiment of the present invention when the battery is being charged. 3, the horizontal axis indicates time (seconds), the vertical axis (left) indicates voltage, and the vertical axis (right) indicates current. The graph in FIG. 3 also shows the voltage of a normal battery cell, the voltage of a defective battery cell, the average voltage of multiple cells, and the charging current of the battery, all measured in a charging state.

[0039] As shown in Fig. 3, the average voltage change amount of the battery cell in one second, the voltage change amount of the normal battery cell, and the voltage change amount of the defective battery cell can be expressed as follows. In addition, when diagnosing an abnormal voltage drop of the battery, the threshold value is set to 15 mV. Meanwhile, in Fig. 3, the time interval is set to 1 second and the threshold value is set to 15 mV, but this can be set arbitrarily by the user.

[0040] Average voltage change of a battery cell: ΔV cell、average =0V (4.083V unchanged)

[0041] Voltage change of normal battery cell: ΔV cell、normal =4.097V-4.098V=-0.001V |-0.001V-0V|<threshold (15mV)

[0042] Voltage change of a defective battery cell: ΔV cell、abnormal =4.123V-4.095V=0.028V |0.028V-0V|>Threshold (15mV)

[0043] In this way, in the case of a normal battery cell, the difference between the individual voltage change amount and the average voltage change amount is less than the threshold value, so it is not determined to be an abnormal voltage drop, whereas in the case of a defective battery cell, the difference between the individual battery voltage change amount and the average voltage change amount is greater than the threshold value, so it is determined to be an abnormal voltage drop.

[0044] FIG. 4 is a diagram showing a diagnosis experiment of a defective cell performed with the battery in a resting state using the battery diagnosis device according to one embodiment of the present invention. 4, the horizontal axis indicates time (seconds), the vertical axis indicates voltage, and the vertical axis (right) indicates current. The graph in FIG. 4 also shows the voltage of a normal battery cell, the voltage of a defective battery cell, the average voltage of multiple cells, and the charging current of the battery, all measured in a resting state.

[0045] In the case of Figure 4, as in Figure 3, the average voltage change of the battery cells over one second, the voltage change of normal battery cells, and the voltage change of defective battery cells can be shown as follows. In addition, when diagnosing an abnormal voltage drop in the battery, the threshold was set to 15 mV.

[0046] Average voltage change of a battery cell: ΔV cell、average =0V (4.142V no change)

[0047] Voltage change of normal battery cell: ΔV cell、normal =0V |0V-0V|<threshold (15mV)

[0048] Voltage change of a defective battery cell: ΔV cell、abnormal =4.123V-4.095V=0.028V |0.028V-0V|>Threshold (15mV)

[0049] In this way, in the case of a normal battery cell, the difference between the individual voltage change amount and the average voltage change amount is less than the threshold value, so it is not determined to be an abnormal voltage drop, whereas in the case of a defective battery cell, the difference between the individual battery voltage change amount and the average voltage change amount is greater than the threshold value, so it is determined to be an abnormal voltage drop.

[0050] In this way, with the battery diagnosis device of one embodiment of the present invention, it is not necessary to check whether the battery is in a hibernating state via a current sensor, and it is possible to detect abnormal voltage drops in battery cells even while the battery is being charged or discharged.

[0051] FIG. 5 is a flowchart showing a battery diagnostic method according to one embodiment of the present invention. 5, first, the voltage of each battery cell is measured for a preset time (S510), at which time the time for measuring the voltage of the battery cell can be arbitrarily set by the user.

[0052] Then, the individual voltage change amount of each battery cell during a preset time is calculated (S520). In step S520, the voltage change amount for each battery cell can be calculated not only in a resting state where no current flows through the battery cell, but also during charging or discharging of the battery cell.

[0053] Next, an average voltage change amount of a plurality of battery cells during a preset time is calculated (S530). At this time, the average voltage change amount of all battery cells included in a specific battery pack can be calculated.

[0054] Furthermore, in steps S520 and S530, in order to reduce the influence according to the resistance of the battery itself, the amount of voltage change of each battery cell can be calculated for the region in which the SOC of the battery cell is equal to or higher than the reference value.

[0055] Then, if there is a battery cell for which the difference between the individual voltage change amount calculated in step S520 and the average voltage change amount calculated in step S530 is greater than a threshold, it is determined that a voltage abnormality has occurred in that battery cell (S540).

[0056] In this case, the threshold value in step S540 may be set according to specifications unique to a manufacturer of the battery cells and the voltage measurement unit (e.g., a battery management system (BMS)). For example, the threshold value may be set in consideration of a voltage measurement error of the voltage measurement unit, a capacity error between battery cells that occurs during the assembly process of the battery module, etc.

[0057] Thus, according to the battery diagnosis method of one embodiment of the present invention, by diagnosing voltage abnormalities in a battery cell by utilizing the voltage change amount of the battery cell without using a separate current sensor, it is possible to detect abnormalities due to sudden battery drops not only in a resting state where no battery voltage flows, but also during charging and discharging of the battery.

[0058] FIG. 6 is a diagram showing a hardware configuration according to an embodiment of the present invention. 6, the battery management device 600 may include a microcontroller 610 (MCU) that controls various processes and components, a memory 620 in which an operating system program and various programs (e.g., a battery pack abnormality diagnosis program or a battery pack temperature estimation program) are recorded, an input / output interface 630 that provides an input interface and an output interface between the battery cell module and / or a switching unit (e.g., a semiconductor switching element), and a communication interface 640 that can communicate with the outside (e.g., a higher-level controller) via a wired or wireless communication network. In this way, the computer program according to the present invention may be recorded in the memory 620 and processed by the microcontroller 610 to be realized as a module that executes, for example, each of the functional blocks shown in FIG. 2.

[0059] Although it has been described above that all components constituting the embodiments of the present invention are combined into one or operate in combination, the present invention is not necessarily limited to such an embodiment. In other words, within the scope of the purpose of the present invention, all components may be selectively combined into one or more and operate.

[0060] In addition, the terms "comprise", "constitute", or "have" described above mean that the relevant element may be contained, unless otherwise specified, and should be interpreted as including other elements, not excluding other elements. All terms, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs, unless otherwise defined. Terms commonly used, such as terms defined in a dictionary, should be interpreted as consistent with the contextual meaning of the relevant art, and should not be interpreted in an idealized or overly formal sense, unless expressly defined in the present invention.

[0061] The above description is merely illustrative of the technical idea of ​​the present invention, and various modifications and variations may be made by those having ordinary knowledge in the technical field to which the present invention pertains, without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are for the purpose of explanation, not for the purpose of limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments. The scope of protection of the present invention should be interpreted according to the claims set forth below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0062] 1 Battery pack 2 Upper controller 10 Battery module 12 Sensors 14 Switching section, semiconductor switching element, switching element 20 BMS, Battery Management System 200 Battery diagnostic device 210 Voltage measurement section 220 Voltage change calculation unit 230 Average voltage change calculation unit 240 Anomaly detection unit 600 Battery management device 610 Microcontroller 620 Memory 630 Input / Output Interface 640 Communication Interface

Claims

1. A battery diagnostic device for detecting a sudden drop in voltage that occurs when an abnormality such as an insulation abnormality in a battery pack or an internal short circuit in a battery cell occurs, comprising: a voltage measuring unit that measures the voltage of each battery cell at a predetermined time interval for a predetermined time; a voltage change amount calculation unit that calculates an individual voltage change amount of each of the battery cells during the preset time; an average voltage change amount calculation unit that calculates an average voltage change amount of a plurality of battery cells during the preset time; an abnormality detection unit that determines, when a difference between the individual voltage change amount and the average voltage change amount of a battery cell is greater than a threshold value, that a voltage abnormality has occurred in the battery cell; Including, the voltage change amount calculation unit calculates a voltage change amount of each of the battery cells during charging or discharging of the battery cells; the voltage change amount calculation unit calculates a voltage change amount of each of the battery cells in a region where a State of Charge (SOC) of the battery cell is equal to or greater than a preset reference value; The predetermined reference value is set according to a type of the battery cell.

2. The battery diagnostic device according to claim 1 , further comprising a memory unit for storing an individual voltage change amount of each of the battery cells and an average voltage change amount of the plurality of battery cells.

3. 3. The battery diagnostic device according to claim 1, wherein the voltage change amount calculation unit calculates the voltage change amount of the battery cell even in a state (rest) in which no current flows through the battery cell.

4. 4. The battery diagnostic device according to claim 1, wherein the threshold value is set in accordance with a specification unique to a manufacturer of the battery cell.

5. 4. The battery diagnostic device according to claim 1, wherein the threshold value is set in accordance with a specification unique to a manufacturer of the voltage measuring unit.

6. The battery diagnostic device according to any one of claims 1 to 3, wherein the threshold value is 15 mV.

7. A battery diagnostic method for detecting a sudden drop in voltage that occurs when an abnormality such as an insulation abnormality in a battery pack or an internal short circuit in a battery cell itself occurs, comprising: measuring the voltage of each battery cell at preset time intervals for a preset time; calculating an individual voltage change amount of each of the battery cells during the preset time; calculating an average voltage change amount of the plurality of battery cells during the preset time; determining that a voltage abnormality has occurred in the battery cell when a difference between the individual voltage change amount and the average voltage change amount is greater than a reference value; Including, the step of calculating the individual voltage change amount includes a step of calculating a voltage change amount of each of the battery cells during charging or discharging of the battery cells; The step of calculating the individual voltage change amount includes calculating the voltage change amount of each of the battery cells in a region where the SOC (State of Charge) of the battery cell is equal to or higher than a preset reference value; The battery diagnosis method, wherein the preset reference value is set according to a type of the battery cell.

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