Battery diagnostic device and method

Abstract

A battery diagnostic device according to an embodiment of the present invention is a device for diagnosing a state of a plurality of battery cells included in a battery module, and includes: a measurement unit that measures voltages of the battery module and each of the plurality of battery cells; and a control unit that is configured to determine a voltage of each of the plurality of battery cells when a voltage of the battery module reaches a predetermined cut-off voltage, determine a voltage increase / decrease pattern for each of the plurality of battery cells based on the determined plurality of voltages and pre-stored voltage data, and diagnose a state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern.

Description

[Technical Field]

[0001] The present invention relates to a battery diagnostic device and method, and more particularly to a battery diagnostic device and method capable of diagnosing the state of a battery.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0139216, filed on October 26, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof. [Background technology]

[0003] Recently, as demand for portable electronic products such as notebook PCs, video cameras, and mobile phones has skyrocketed, and development of electric vehicles, energy storage batteries, robots, and satellites has gained momentum, research into high-performance batteries that can be repeatedly charged and discharged is actively underway.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention due to their advantages over nickel-based batteries, such as almost no memory effect, freedom in charging and discharging, a very low self-discharge rate, and high energy density.

[0005] As electric vehicles, electric motorbikes, electric bicycles, and other power-driven devices are becoming more commercially available, there is an increasing demand for batteries with high capacity and performance. For example, a battery module may be configured by connecting a plurality of battery cells in series and / or in parallel.

[0006] However, since the plurality of battery cells connected to each other do not deteriorate at the same rate, there is a problem in that the state of each of the plurality of battery cells cannot be accurately diagnosed based on the state of the battery module. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a battery diagnostic device and method for diagnosing the state of each of a plurality of batteries connected to each other.

[0008] Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to an embodiment of the present invention; FIG. 2 is a block diagram of a semiconductor device according to an embodiment of the present invention; [Means for solving the problem]

[0009] A battery diagnostic device according to one aspect of the present invention may be a device for diagnosing the state of a plurality of battery cells included in a battery module.

[0010] The battery diagnostic device may include a measurement unit configured to measure a voltage of a battery module and each of the plurality of battery cells; and a control unit configured to determine a voltage of each of the plurality of battery cells when the voltage of the battery module reaches a predetermined cutoff voltage, determine a voltage increase / decrease pattern of each of the plurality of battery cells based on the determined plurality of voltages and pre-stored voltage data, and diagnose a state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern.

[0011] The pre-stored voltage data may be set to include reference voltages of the plurality of battery cells measured each time the voltage of the battery module reaches the cut-off voltage.

[0012] The controller may be configured to determine the voltage increase / decrease pattern for each of the plurality of battery cells based on the determined voltage and one or more reference voltages included in the pre-stored voltage data.

[0013] The control unit may be configured to derive a relational expression between the determined voltage and the one or more reference voltages for each of the plurality of battery cells, and to determine the voltage increase / decrease pattern for each of the plurality of battery cells based on the derived relational expression.

[0014] The control unit may be configured to diagnose a state of the battery cell based on whether the determined voltage increase / decrease pattern is moving toward the cut-off voltage.

[0015] The control unit may be configured to determine a charging voltage of each of the plurality of battery cells when a voltage of the battery module reaches a predetermined charging cut-off voltage, and to determine a first voltage increase / decrease pattern of each of the plurality of battery cells based on the determined charging voltage and the pre-stored voltage data.

[0016] The control unit may be configured to determine a discharge voltage of each of the plurality of battery cells when the voltage of the battery module reaches a predetermined discharge cut-off voltage, and to determine a second voltage increase / decrease pattern of each of the plurality of battery cells based on the determined discharge voltage and the pre-stored voltage data.

[0017] The control unit may be configured to diagnose a state of each of the plurality of battery cells based on the first voltage increase / decrease pattern and the second voltage increase / decrease pattern.

[0018] The control unit may be configured to diagnose a state of a battery cell in which the first voltage increase / decrease pattern is a voltage increase pattern and the second voltage increase / decrease pattern is a voltage decrease pattern as an accelerated degradation state.

[0019] The measurement unit may be configured to diagnose a state of a battery cell in which the first voltage increase / decrease pattern is a voltage decrease pattern and the second voltage increase / decrease pattern is a voltage increase pattern as a slow degradation state.

[0020] The measurement unit may be configured to further measure a current of the battery module.

[0021] The control unit may be configured to calculate a capacity of the battery module based on a current of the battery module, and diagnose a condition of each of the plurality of battery cells when the calculated capacity is reduced from a previously calculated capacity.

[0022] The control unit may be configured to, when the capacity of the battery module is within a predetermined range from a preset initial capacity, diagnose the states of the remaining battery cells among the plurality of battery cells, excluding a battery cell whose determined voltage is the same as the cut-off voltage.

[0023] A battery pack according to another aspect of the present invention may include a battery diagnostic device according to one aspect of the present invention.

[0024] A battery diagnostic method according to yet another aspect of the present invention may be a battery diagnostic method for diagnosing the states of a plurality of battery cells included in a battery module.

[0025] The battery diagnosis method may include a voltage measurement step of measuring a voltage of the battery module and each of the plurality of battery cells; a voltage determination step of determining a voltage of each of the plurality of battery cells when the voltage of the battery module reaches a predetermined cut-off voltage; a voltage increase / decrease pattern determination step of determining a voltage increase / decrease pattern for each of the plurality of battery cells based on the determined plurality of voltages and pre-stored voltage data; and a battery diagnosis step of diagnosing a state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern. [Effects of the Invention]

[0026] According to one aspect of the present invention, the battery diagnostic device has an advantage in that it can specifically diagnose the state of each of the plurality of battery cells by considering whether charging / discharging of the battery module has been completed and the voltage increase / decrease patterns of the plurality of battery cells.

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

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention, so the present invention should not be interpreted as being limited to the matters described in the drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a diagram illustrating a battery diagnostic device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a diagnostic rule according to an embodiment of the present invention. [Figure 3] 4 is a diagram illustrating a battery module according to an embodiment of the present invention and charging voltages of a plurality of battery cells. [Figure 4] 4 is a diagram illustrating a battery module according to an embodiment of the present invention and a discharge voltage of a plurality of battery cells. [Figure 5] FIG. 10 is a diagram illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention. [Figure 6] 10 is a diagram illustrating a battery diagnostic method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best explain the invention.

[0031] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0032] Furthermore, if a detailed description of known functions or configurations related to the present invention is deemed to obscure the gist of the present invention, that description will be omitted.

[0033] Terms including ordinal numbers such as "first," "second," etc. are used to distinguish one of various components from the rest, and do not limit the components.

[0034] Furthermore, throughout the specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but that it may further include other components, unless otherwise specified.

[0035] Furthermore, throughout this specification, when a part is said to be "coupled" to another part, this includes not only "directly coupled" but also "indirectly coupled" via another element in between.

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0037] FIG. 1 is a diagram illustrating a battery diagnostic device 100 according to an embodiment of the present invention.

[0038] The battery diagnostic device 100 may be configured to diagnose the condition of a battery cell included in a battery module.

[0039] Here, a battery cell refers to a single independent cell that has a negative terminal and a positive terminal and is physically separable. As an example, a lithium ion battery or a lithium polymer battery may be considered a battery cell. A plurality of battery cells may be connected in series and / or parallel to form a battery module. In some embodiments, a plurality of battery cells may be connected in series and / or parallel to form a battery pack. For convenience of explanation, the following description will be given of a plurality of battery cells included in a battery module, but the present invention is also applicable to a plurality of battery cells included in a battery pack.

[0040] Referring to FIG. 1, a battery diagnostic device 100 may include a measurement unit 110 and a control unit 120.

[0041] The measuring unit 110 may be configured to measure the voltage of the battery module and each of the plurality of battery cells.

[0042] Specifically, the measurement unit 110 may be electrically connected to the positive and negative terminals of the battery module, and may measure the voltage of the battery module by measuring the positive and negative voltages of the battery module.

[0043] The measuring unit 110 may be electrically connected to the positive and negative terminals of each of the plurality of battery cells included in the battery module, and may measure the voltage of each battery cell by measuring the positive and negative voltages of each of the plurality of battery cells.

[0044] The measurement unit 110 may be communicatively connected to the control unit 120. For example, the measurement unit 110 may be connected to the control unit 120 by wire and / or wirelessly. The measurement unit 110 may transmit information related to the measured voltages of the battery module and the plurality of battery cells to the control unit 120.

[0045] The controller 120 may be configured to determine the voltage of each of the plurality of battery cells when the voltage of the battery module reaches a preset cutoff voltage.

[0046] Specifically, a cutoff voltage for the battery module may be preset. Here, the cutoff voltage may include a charge end voltage and a discharge end voltage of the battery module. For example, when the voltage of the battery module reaches the charge cutoff voltage, charging of the battery module may be terminated. In another example, when the voltage of the battery module reaches the discharge cutoff voltage, discharging of the battery module may be terminated.

[0047] For example, assuming that the voltage of the battery module reaches the charge cutoff voltage at time a, the control unit 120 may determine the voltage of each of the plurality of battery cells measured at time a.

[0048] In another example, assuming that the voltage of the battery module reaches the discharge cutoff voltage at time b, the control unit 120 may determine the voltage of each of the plurality of battery cells measured at time b.

[0049] The control unit 120 may be configured to determine a voltage increase / decrease pattern for each of the plurality of battery cells based on the determined plurality of voltages and pre-stored voltage data.

[0050] Here, the pre-stored voltage data may be set to include reference voltages of the plurality of battery cells measured each time the voltage of the battery module reaches the cut-off voltage. Specifically, the pre-stored voltage data may include data related to voltages of the battery module and the plurality of battery cells measured at a past time. Preferably, the pre-stored voltage data may include data related to voltages of the plurality of battery cells determined each time the voltage of the battery module reaches the cut-off voltage at a past time.

[0051] The control unit 120 may be configured to determine a voltage increase / decrease pattern for each of the plurality of battery cells based on the determined voltage and one or more reference voltages included in the pre-stored voltage data. Here, the voltage increase / decrease pattern is a pattern indicating a trend of the current battery cell voltage, and may be determined by comparing the reference voltage of the battery cell measured at a previous point in time with the voltage of the battery cell measured at a current point in time.

[0052] Preferably, the voltage increase / decrease pattern may be classified into a voltage increase pattern or a voltage decrease pattern. Here, the voltage maintenance pattern is a pattern in which the voltage of the battery cell is maintained constant from the past to the present. The voltage increase pattern is a pattern in which the voltage of the battery cell is increasing compared to the past. The voltage decrease pattern is a pattern in which the voltage of the battery cell is decreasing compared to the past.

[0053] For example, assume that a battery module includes one battery cell, the current time is time t+3, and the pre-stored voltage data includes reference voltages of the battery module and the battery cell at time t, t+1, and t+2. The control unit 120 may determine a voltage increase / decrease pattern for the battery cell voltages measured at time t, t+1, t+2, and t+3 and the reference voltage. A specific example of determining the voltage increase / decrease pattern will be described later.

[0054] The control unit 120 may be configured to diagnose the state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern.

[0055] Specifically, the control unit 120 may diagnose the deterioration state of the battery cell based on the voltage increase / decrease pattern. Preferably, the control unit 120 may diagnose the deterioration progress state of the battery cell.

[0056] For example, the control unit 120 may diagnose the state of the battery cell as an accelerated degradation state or a slow degradation state.

[0057] Here, the slow degradation state may refer to a state in which a battery cell deteriorates at a normal degradation rate. That is, a battery cell in the slow degradation state may be a battery cell in a normal state that deteriorates at a predictable degradation rate. Conversely, the accelerated degradation state may refer to a state in which degradation of a battery cell progresses rapidly. That is, a battery cell in the accelerated degradation state may be a battery cell in an abnormal state that deteriorates rapidly outside a predicted range. The predictable degradation rate and the range of the predictable degradation rate that can distinguish the accelerated degradation state from the slow degradation state may be appropriately set through experiments, simulations, etc.

[0058] Typically, when charging / discharging of a battery module ends, charging / discharging of the battery cells included in the battery module also ends. That is, the end point of charging / discharging of the battery module can be a reference point for determining a change in the state of the battery cells. For example, if a specific SOC or a specific capacity of the battery module is used as the reference point, the reference point may change if the capacity of the battery module decreases due to deterioration. In contrast, if the end point of charging / discharging of the battery module is used as the reference point, the state of the battery cells can be diagnosed using the same criteria even if the capacity of the battery module changes.

[0059] Therefore, the battery diagnostic device 100 according to an embodiment of the present invention has an advantage in that it can specifically diagnose the state of each of the plurality of battery cells by considering whether charging / discharging of the battery module has been completed and the voltage increase / decrease patterns of the plurality of battery cells.

[0060] Meanwhile, the control unit 120 included in the battery diagnostic device 100 may selectively include a processor, an application-specific integrated circuit (ASIC), other chipsets, logic circuits, registers, a communication modem, a data processing device, etc., known in the art, to execute various control logics performed in the present invention. When the control logic is embodied as software, the control unit 120 may be embodied as a collection of program modules. In this case, the program modules may be stored in a memory and executed by the control unit 120. The memory may be internal or external to the control unit 120 and may be connected to the control unit 120 by various known means.

[0061] The battery diagnostic device 100 may further include a storage unit 130. The storage unit 130 may store data and programs required for each component of the battery diagnostic device 100 to operate and function, or data generated during the operation and function. The storage unit 130 may be any known information storage means capable of recording, erasing, updating, and reading data. Examples of the information storage means include RAM, flash memory, ROM, EEPROM, and registers. The storage unit 130 may also store program code defining processes executable by the control unit 120.

[0062] For example, the storage unit 130 may store voltage data related to reference voltages of a plurality of battery cells, and the control unit 120 may access the storage unit 130 to obtain the stored voltage data.

[0063] Hereinafter, an embodiment will be described in which the control unit 120 determines a voltage increase / decrease pattern of the battery cell based on the voltage and the reference voltage.

[0064] According to one embodiment of the present invention, the controller 120 may be configured to derive a relationship between the determined voltage and one or more reference voltages for each of the plurality of battery cells.

[0065] For example, the control unit 120 may derive a relational expression relating to the determined voltage and one or more reference voltages using a fitting algorithm. Here, the derived relational expression may be a function that can represent the reference voltage of the battery cell at a past point in time and the voltage of the battery cell at a present point in time.

[0066] The control unit 120 may be configured to determine a voltage increase / decrease pattern for each of the plurality of battery cells based on the derived relational expression.

[0067] For example, the control unit 120 may calculate an instantaneous change rate for the current time point based on the derived relational expression. Then, the control unit 120 may determine a voltage increase / decrease pattern of the battery cell based on the calculated instantaneous change rate. If the instantaneous change rate is a positive number, the control unit 120 may determine the voltage increase / decrease pattern of the battery cell as a voltage increase pattern. If the instantaneous change rate is 0, the control unit 120 may determine the voltage increase / decrease pattern of the battery as a voltage maintenance pattern. If the instantaneous change rate is a negative number, the control unit 120 may determine the voltage increase / decrease pattern of the battery as a voltage decrease pattern.

[0068] The battery diagnostic device 100 according to an embodiment of the present invention has an advantage in that it can accurately determine a voltage increase / decrease pattern for a plurality of battery cells based on a relationship between a current voltage and a past reference voltage, and the state of the plurality of battery cells can be diagnosed with high accuracy based on the determined voltage increase / decrease pattern.

[0069] The control unit 120 may be configured to diagnose the state of the battery cell depending on whether the determined voltage increase / decrease pattern is moving toward the cutoff voltage.

[0070] Specifically, the controller 120 may determine a first voltage increase / decrease pattern for each of the battery cells during charging of the battery module, and may determine a second voltage increase / decrease pattern for each of the battery cells during discharging of the battery module. Here, the first voltage increase / decrease pattern and the second voltage increase / decrease pattern may be independent of each other. That is, the first voltage increase / decrease pattern may not affect the second voltage increase / decrease pattern.

[0071] The control unit 120 may be configured to determine a charging voltage of each of the plurality of battery cells when the voltage of the battery module reaches a preset charging cut-off voltage. The control unit 120 may be configured to determine a first voltage increase / decrease pattern of each of the plurality of battery cells based on the determined charging voltage and pre-stored voltage data.

[0072] For example, the control unit 120 may determine a first voltage increase / decrease pattern for each of the plurality of battery cells based on the determined charging voltage and a reference charging voltage included in pre-stored voltage data.

[0073] The control unit 120 may be configured to determine a discharge voltage of each of the plurality of battery cells when the voltage of the battery module reaches a preset discharge cut-off voltage, and may be configured to determine a second voltage increase / decrease pattern of each of the plurality of battery cells based on the determined discharge voltage and pre-stored voltage data.

[0074] For example, the control unit 120 may determine a second voltage increase / decrease pattern for each of the plurality of battery cells based on the determined discharge voltage and a reference discharge voltage included in pre-stored voltage data.

[0075] The control unit 120 may be configured to diagnose the state of each of the plurality of battery cells based on the first voltage increase / decrease pattern and the second voltage increase / decrease pattern.

[0076] 2 is a diagram illustrating a diagnosis rule according to an embodiment of the present invention, specifically, a diagram illustrating the state of a battery cell diagnosed by a first voltage increase / decrease pattern and a second voltage increase / decrease pattern of the battery cell.

[0077] Referring to FIG. 2, the controller 120 may diagnose the state of the battery cell as an accelerated degradation state or a slow degradation state by taking into consideration both the first voltage increase / decrease pattern and the second voltage increase / decrease pattern.

[0078] For example, the control unit 120 may diagnose a state of a battery cell in which the first voltage increase / decrease pattern is a voltage increase pattern and the second voltage increase / decrease pattern is a voltage decrease pattern as an accelerated deterioration state.

[0079] In another example, the control unit 120 may diagnose a state of a battery cell in which the first voltage increase / decrease pattern is a voltage decrease pattern and the second voltage increase / decrease pattern is a voltage increase pattern as a slow degradation state.

[0080] The battery diagnostic device 100 according to one embodiment of the present invention has an advantage in that it can diagnose the state of a battery cell more accurately by considering both a first voltage increase / decrease pattern (a voltage increase / decrease pattern in a charging state) and a second voltage increase / decrease pattern (a voltage increase / decrease pattern in a discharging state) which are independent of each other.

[0081] 3 is a diagram illustrating a charging voltage of a battery module and a plurality of battery cells according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a discharging voltage of a battery module and a plurality of battery cells according to an embodiment of the present invention.

[0082] Specifically, FIG. 3 is a diagram showing the charging voltages of the first battery cell B1, the second battery cell B2, the third battery cell B3, and the fourth battery cell B4, and the charging cut-off voltage VC of the battery module. More specifically, FIG. 3 is a diagram showing the charging reference voltages of the plurality of battery cells B1, B2, B3, and B4 included in pre-stored voltage data, and the voltages determined in the current cycle (400th cycle). FIG. 4 is a diagram showing the discharging voltages of the first battery cell B1, the second battery cell B2, the third battery cell B3, and the fourth battery cell B4, and the discharging cut-off voltage VDC of the battery module. More specifically, FIG. 4 is a diagram showing the discharging reference voltages of the plurality of battery cells B1, B2, B3, and B4, and the voltages determined in the current cycle (400th cycle). Below, the voltage increase / decrease patterns of the plurality of battery cells B1, B2, B3, and B4 will be described based on the 400th cycle.

[0083] 3, based on 400 cycles, the voltages of the first battery cell B1 and the third battery cell B3 are increasing, the voltage of the fourth battery cell B4 is maintaining, and the voltage of the second battery cell B2 is decreasing. Therefore, the first voltage increase / decrease pattern of the first battery cell B1 and the third battery cell B3 can be determined as a voltage increase pattern. The first voltage increase / decrease pattern of the fourth battery cell B4 can be determined as a voltage maintenance pattern. The first voltage increase / decrease pattern of the second battery cell B2 can be determined as a voltage decrease pattern.

[0084] 4, based on the 400th cycle, the voltages of the first battery cell B1 and the second battery cell B2 are maintained, the voltage of the third battery cell B3 is decreasing, and the voltage of the fourth battery cell B4 is also decreasing. Therefore, the second voltage increase / decrease pattern of the first battery cell B1 and the second battery cell B2 may be determined as a voltage maintaining pattern. The second voltage increase / decrease pattern of the third battery cell B3 may be determined as a voltage decreasing pattern. The second voltage increase / decrease pattern of the fourth battery cell B4 may be determined as a voltage decreasing pattern.

[0085] That is, the first voltage increase / decrease pattern of the first battery cell B1 may be determined as a voltage increase pattern, and the second voltage increase / decrease pattern may be determined as a voltage maintaining pattern. The first voltage increase / decrease pattern of the second battery cell B2 may be determined as a voltage decreasing pattern, and the second voltage increase / decrease pattern may be determined as a voltage maintaining pattern. The first voltage increase / decrease pattern of the third battery cell B3 may be determined as a voltage increase pattern, and the second voltage increase / decrease pattern may be determined as a voltage decreasing pattern. The first voltage increase / decrease pattern of the fourth battery cell B4 may be determined as a voltage maintaining pattern, and the second voltage increase / decrease pattern may be determined as a voltage decreasing pattern.

[0086] Referring to FIG. 3, the controller 120 may diagnose the state of the third battery cell B3, in which the first voltage increase / decrease pattern is a voltage increase pattern and the second voltage increase / decrease pattern is a voltage decrease pattern, as an accelerated degradation state.

[0087] In one embodiment, the measuring unit 110 may be configured to further measure the current of the battery module.

[0088] Specifically, the measurement unit 110 may measure a charging current applied to the battery module and a discharging current output from the battery module.

[0089] The control unit 120 may be configured to calculate the capacity of the battery module based on the current of the battery module.

[0090] The control unit 120 may be configured to diagnose the state of each of the plurality of battery cells when the calculated capacity is decreased from the previously calculated capacity. The control unit 120 may first determine whether or not the capacity of the battery module has decreased, and when the decrease in capacity is confirmed, may determine a voltage increase / decrease pattern for each of the plurality of battery cells.

[0091] For example, if the currently calculated capacity of the battery module is lower than the previously calculated capacity of the battery module, the control unit 120 may determine a voltage increase / decrease pattern for each of the plurality of battery cells. Here, the previously calculated capacity of the battery module may be stored in the storage unit 130. The control unit 120 may then store the currently calculated battery capacity in the storage unit 130.

[0092] The battery diagnostic device 100 according to an embodiment of the present invention may determine the voltage increase / decrease pattern of the plurality of battery cells only when necessary by first determining whether the capacity of the battery module has decreased. That is, when the capacity of the battery module has not decreased, the system resources required for determining the voltage increase / decrease pattern of the plurality of battery cells are prevented from being wasted.

[0093] In one embodiment, the control unit 120 may be configured to diagnose the state of the remaining battery cells among the plurality of battery cells, excluding the battery cell whose determined voltage is the same as the cutoff voltage, when the capacity of the battery module is within a predetermined range from a preset initial capacity.

[0094] Specifically, when the capacity of the battery module is within a predetermined range from a preset initial capacity, a battery cell whose determined voltage is the same as the cutoff voltage (hereinafter, referred to as a diagnosis pending cell) may be a battery cell with a high initial resistance or a low initial capacity. That is, due to its characteristics, the voltage of the diagnosis pending cell in the initial cycle may be indicated as the same as the cutoff voltage of the battery module. Therefore, to improve diagnostic accuracy, the battery diagnostic device 100 may diagnose the condition of only the battery cells excluding the diagnosis pending cell among the plurality of battery cells.

[0095] The battery diagnostic device 100 according to the present invention may be applied to a BMS (Battery Management System). That is, the BMS according to the present invention may include the battery diagnostic device 100 described above. In this configuration, at least some of the components of the battery diagnostic device 100 may be implemented by complementing or adding functions of components included in a conventional BMS. For example, the measurement unit 110, the control unit 120, and the storage unit 130 of the battery diagnostic device 100 may be implemented as components of the BMS.

[0096] The battery diagnostic device 100 according to the present invention may be provided in a battery pack. That is, the battery pack according to the present invention may include the battery diagnostic device 100 and one or more battery cells. The battery pack may further include electrical components (relays, fuses, etc.), a case, etc.

[0097] FIG. 5 is a diagram schematically illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention.

[0098] The positive terminal of the battery module may be electrically connected to the positive terminal P+ of the battery pack, and the negative terminal of the battery module may be electrically connected to the negative terminal P- of the battery pack.

[0099] The battery module may include a first battery cell B1, a second battery cell B2, a third battery cell B3, and a fourth battery cell B4 connected in series. Although the embodiment of Fig. 5 shows a series connection, multiple battery cells may be connected in series and / or in parallel.

[0100] The measurement unit 110 may be connected to the first sensing line and the second sensing line.

[0101] The measurement unit 110 may be electrically connected to the battery module through a first sensing line, and may measure the voltage of the battery module and the voltages of the battery cells B1, B2, B3, and B4 through the first sensing line.

[0102] The measuring unit 110 may be electrically connected to a current measuring unit via a second sensing line. For example, the current measuring unit may be an ammeter or a shunt resistor. The measuring unit 110 may measure the charging current and discharging current of the battery module via the second sensing line.

[0103] An external device can be electrically connected to the positive terminal P+ and the negative terminal P- of the battery pack, for example, a charging device or a load.

[0104] FIG. 6 is a diagram illustrating a battery diagnostic method according to another embodiment of the present invention.

[0105] Preferably, each step of the battery diagnostic method may be performed by the battery diagnostic device 100. Hereinafter, for the sake of convenience, the overlapping content with the above content will be omitted or will be briefly described.

[0106] Referring to FIG. 6, the battery diagnostic method may include a voltage measurement step, a voltage determination step, a voltage increase / decrease pattern determination step, and a battery diagnostic step.

[0107] The voltage measuring step is a step of measuring the voltage of the battery module and each of the plurality of battery cells, and may be performed by the measuring unit 110.

[0108] The voltage determining step may be performed by the control unit 120 to determine the voltage of each of the battery cells when the voltage of the battery module reaches a preset cutoff voltage.

[0109] For example, when the voltage of the battery module reaches the charging cutoff voltage, the control unit 120 may determine the charging voltage of each of the plurality of battery cells.

[0110] In another example, when the voltage of the battery module reaches the discharge cutoff voltage, the control unit 120 may determine the discharge voltage of each of the plurality of battery cells.

[0111] The voltage increase / decrease pattern determining step may be performed by the control unit 120 to determine a voltage increase / decrease pattern for each of the battery cells based on the determined voltages and pre-stored voltage data.

[0112] For example, the control unit 120 may determine a first voltage increase / decrease pattern and a second voltage increase / decrease pattern for each of the plurality of battery cells.

[0113] Specifically, the control unit 120 may determine a first voltage increase / decrease pattern based on a charging voltage of the battery cell and a reference charging voltage of the battery cell among pre-stored voltage data. The control unit 120 may also determine a second voltage increase / decrease pattern based on a discharging voltage of the battery cell and a reference discharging voltage of the battery cell among pre-stored voltage data. Here, the first voltage increase / decrease pattern and the second voltage increase / decrease pattern may be determined as a voltage maintaining pattern, a voltage increase pattern, or a voltage decrease pattern, and may be independent of each other.

[0114] The battery diagnosis step is a step of diagnosing the state of each of the battery cells according to the determined voltage increase / decrease pattern, and may be performed by the control unit 120.

[0115] For example, when the capacity of the battery module decreases, the control unit 120 may diagnose the state of the battery cell in which the first voltage increase / decrease pattern is a voltage increase pattern and the second voltage increase / decrease pattern is a voltage decrease pattern as an accelerated deterioration state.

[0116] In another example, when the capacity of the battery module decreases, the control unit 120 may diagnose the state of the battery cell in which the first voltage increase / decrease pattern is a voltage decrease pattern and the second voltage increase / decrease pattern is a voltage increase pattern as a slow degradation state.

[0117] The embodiments of the present invention described above are not necessarily embodied through devices and methods, but may be embodied through a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation should be easily embodied by a person skilled in the art to which the present invention pertains from the description of the above-mentioned embodiments.

[0118] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the scope of the claims.

[0119] Furthermore, since the above-mentioned present invention can be variously replaced, modified, and changed by a person having ordinary knowledge in the technical field to which the present invention belongs without departing from the technical concept of the present invention, it is not limited to the above-mentioned embodiments and the attached drawings, and can be configured by selectively combining all or part of each embodiment to make various modifications. [Explanation of symbols]

[0120] 1 battery pack 100 Battery diagnostic device 110 Measuring section 120 control section 130 Preservation Department BM Battery Module B1 1st battery cell B2 Second battery cell B3 Third battery cell B4 4th battery cell

Claims

1. A battery diagnostic device for diagnosing the state of a plurality of battery cells included in a battery module, a measurement unit for measuring the voltage of the battery module and each of the plurality of battery cells; a control unit configured to determine a voltage of each of the plurality of battery cells when a voltage of the battery module reaches a preset cut-off voltage, determine a voltage increase / decrease pattern of each of the plurality of battery cells based on the determined plurality of voltages and pre-stored voltage data, and diagnose a state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern.

2. The pre-stored voltage data is The reference voltages are set to include reference voltages of the plurality of battery cells measured each time the voltage of the battery module reaches the cut-off voltage; The control unit 2. The battery diagnostic device of claim 1, configured to determine the voltage increase / decrease pattern for each of the plurality of battery cells based on the determined voltage and one or more reference voltages included in the pre-stored voltage data.

3. The control unit 3. The battery diagnostic device according to claim 2, wherein the battery diagnostic device is configured to derive a relational expression between the determined voltage and the one or more reference voltages for each of the plurality of battery cells, and determine the voltage increase / decrease pattern for each of the plurality of battery cells based on the derived relational expression.

4. The control unit The battery diagnostic device according to claim 1 , further comprising: a battery diagnostic device configured to diagnose the state of the battery cell based on whether the determined voltage increase / decrease pattern approaches the cutoff voltage.

5. The control unit determining a charging voltage of each of the plurality of battery cells when the voltage of the battery module reaches a predetermined charging cut-off voltage; and determining a first voltage increase / decrease pattern for each of the plurality of battery cells based on the determined charging voltage and the pre-stored voltage data; determining a discharge voltage of each of the plurality of battery cells when the voltage of the battery module reaches a predetermined discharge cut-off voltage; and determining a second voltage increase / decrease pattern of each of the plurality of battery cells based on the determined discharge voltage and the pre-stored voltage data; The battery diagnostic device according to claim 1 , further comprising: a battery diagnostic device configured to diagnose a state of each of the plurality of battery cells based on the first voltage increase / decrease pattern and the second voltage increase / decrease pattern.

6. The control unit diagnosing a state of the battery cell in which the first voltage increase / decrease pattern is a voltage increase pattern and the second voltage increase / decrease pattern is a voltage decrease pattern as an accelerated deterioration state; 6. The battery diagnostic device according to claim 5, wherein the battery cell in which the first voltage increase / decrease pattern is a voltage decrease pattern and the second voltage increase / decrease pattern is a voltage increase pattern is diagnosed as being in a slow degradation state.

7. The measurement unit further configured to measure the current of the battery module; The control unit 2. The battery diagnostic device according to claim 1, further comprising: a battery module current calculation unit configured to calculate a capacity of the battery module based on a current of the battery module; and, if the calculated capacity is lower than a previously calculated capacity, to diagnose a state of each of the plurality of battery cells.

8. The control unit 10. The battery diagnostic device according to claim 7, wherein, when the capacity of the battery module is within a predetermined range from a preset initial capacity, the device is configured to diagnose the states of the remaining battery cells, excluding battery cells whose determined voltage is the same as the cut-off voltage, among the plurality of battery cells.

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

10. A battery diagnostic method for diagnosing the state of a plurality of battery cells included in a battery module, comprising: measuring a voltage of the battery module and each of the plurality of battery cells; a voltage determining step of determining a voltage of each of the plurality of battery cells when a voltage of the battery module reaches a predetermined cutoff voltage; determining a voltage increase / decrease pattern for each of the battery cells based on the determined voltages and pre-stored voltage data; and diagnosing a state of each of the plurality of battery cells according to the determined voltage increase / decrease pattern.

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