Battery Management Device

Abstract

To provide a battery management device that allows for appropriate setting of parameters for determining the allowable input current value. [Solution] The battery management device according to this disclosure includes a high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or higher to a lithium-ion secondary battery; an impedance detection unit that detects the actual AC impedance of the lithium-ion secondary battery to which the high-frequency signal has been supplied; a determination unit that determines whether or not Li has been deposited in the lithium-ion secondary battery based on the actual AC impedance of the lithium-ion secondary battery; and an update unit that updates parameters for determining the allowable input current value to the lithium-ion secondary battery based on the charging pattern of the lithium-ion secondary battery in the case of Li deposition.

Description

[Technical Field]

[0001] This disclosure relates to a battery management device. [Background technology]

[0002] To prevent performance degradation of lithium-ion secondary batteries, it is necessary to suppress the deposition of metallic lithium (Li) in lithium-ion secondary batteries (hereinafter referred to as Li deposition). However, no non-destructive method for detecting Li deposition in lithium-ion secondary batteries was known.

[0003] In response to this, as disclosed in Patent Document 1, the inventors have developed a method for detecting the real part of the AC impedance of a lithium-ion secondary battery using a high-frequency signal, and for calculating the amount of Li deposited in the lithium-ion secondary battery based on the difference between the current value and the initial value of the real part of the AC impedance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7347451 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, since lithium deposition progresses with increasing charging power, an allowable charging power is set for each type of lithium-ion secondary battery from the perspective of suppressing lithium deposition. However, the rate of lithium deposition in lithium-ion secondary batteries varies from product to product (e.g., standard deviation σ) even within the same type. In conventional lithium-ion secondary batteries, for example, the allowable charging power for each type was set excessively low (fixed) to prevent lithium deposition from progressing in products within a range of ±6σ, which resulted in the problem of long charging times.

[0006] Therefore, the inventors have developed a method of reducing the allowable charging power according to the amount of Li deposition calculated using the method disclosed in Patent Document 1. By this method, for example, in products included in the range of ±3σ, the allowable charging power at the start of use can be set high enough so that Li deposition does not progress, and the charging time can also be shortened.

[0007] By the way, the method disclosed in Patent Document 1 has room for application in determining the allowable input current value used for controlling the allowable charging power.

[0008] The present disclosure has been made in view of the above background, and an object thereof is to provide a battery management device capable of appropriately setting parameters for determining an allowable input current value.

Means for Solving the Problems

[0009] The battery management device according to the present disclosure includes a high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or more to a lithium-ion secondary battery, an impedance detection unit that detects a real part of an AC impedance of the lithium-ion secondary battery to which the high-frequency signal is supplied, a determination unit that determines whether Li has been deposited in the lithium-ion secondary battery based on the real part of the AC impedance of the lithium-ion secondary battery, and an update unit that updates parameters for determining an allowable input current value to the lithium-ion secondary battery based on a charging pattern of the lithium-ion secondary battery when Li has been deposited.

Effects of the Invention

[0010] According to the present disclosure, a battery management device capable of appropriately setting parameters for determining an allowable input current value can be provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a block diagram showing a configuration example of a battery management system according to the present disclosure. [Figure 2]It is a diagram showing the relationship between the SOH of a secondary battery and the change amount of the real part Z of the AC impedance when a high-frequency signal of 1 MHz is supplied to the secondary battery. [Figure 3] It is a diagram showing the relationship between the frequency of the AC signal supplied to the secondary battery and the real part of the AC impedance detected from the secondary battery. [Figure 4] It is a diagram showing the relationship between the frequency of the AC signal supplied to the secondary battery and the real part of the AC impedance detected from the secondary battery. [Figure 5] It is a flowchart illustrating the operation of the battery management device according to the present disclosure. [Figure 6] It is a block diagram showing a configuration example of the battery management system according to the present disclosure.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are simplified as appropriate.

[0013] <Embodiment 1> FIG. 1 is a block diagram showing a configuration example of a battery management system according to Embodiment 1. As shown in FIG. 1, the battery management system 1 includes a battery management device 10 and a secondary battery 20 managed by the battery management device 10.

[0014] The secondary battery 20 is a lithium-ion secondary battery and is composed of a cell stack formed by stacking a plurality of battery cells and a case for housing the cell stack.

[0015] Each battery cell includes a positive electrode, a negative electrode, and an ion transmission medium provided between the positive electrode and the negative electrode for conducting carrier ions. A separator may be further provided between the positive electrode and the negative electrode. Resins such as polyethylene and polypropylene are used for the separator.

[0016] For example, positive electrode active materials include sulfides containing transition metal elements and oxides containing lithium and transition metal elements. Specifically, positive electrode active materials have the basic composition formula Li (1-x) MnO2 (but 0 <x<1)やLi (1-x) Lithium manganese composite oxides such as Mn2O4, with the basic composition formula being Li (1-x) Lithium cobalt composite oxides such as CoO2, with the basic composition formula being Li (1-x) Lithium nickel composite oxides such as NiO2, or the basic composition formula Li (1-x) Ni a Co b Mn c Lithium nickel cobalt manganese composite oxides such as O2 (where a+b+c=1) are used. Note that the positive electrode active material may include other elements in addition to the basic composition formula described above. For the positive electrode current collector, for example, aluminum (Al) is used.

[0017] For example, composite oxides containing lithium or carbon materials are used as the negative electrode active material. Specifically, the negative electrode active material may be an inorganic compound such as lithium, lithium alloys, or tin compounds, a carbon material capable of intercalating and deintercalating lithium ions, a composite oxide containing multiple elements, or a conductive polymer. Examples of carbon materials used for the negative electrode active material include coke, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, or carbon fibers, but graphites such as artificial graphite or natural graphite are preferred. Examples of composite oxides used for the negative electrode active material include lithium titanium composite oxide and lithium vanadium composite oxide. For the current collector of the negative electrode, for example, Cu (copper) is used.

[0018] The ion-conducting medium is used as an electrolyte, for example, by dissolving a supporting salt. Lithium salts such as LiPF6 and LiBF4 are used as supporting salts. The solvent for the electrolyte is one or a mixture of several of the following: carbonates, esters, ethers, nitriles, furans, sulforanes, and dioxolanes. Examples of carbonates include cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, and linear carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, and t-butyl-i-propyl carbonate. Alternatively, the ion-conducting medium may be a solid ion-conducting polymer, an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bound together by an organic binder.

[0019] The battery management device 10 manages the charging of the secondary battery 20 under management. For example, the battery management device 10 non-destructively detects the presence or absence of Li deposition in the secondary battery 20 and provides feedback control of the allowable charging power (upper limit of charging power) Pa for the secondary battery 20 based on the detection result.

[0020] The battery management device 10 includes a high-frequency signal supply unit 11, an impedance detection unit 12, a determination unit 13, a control unit 14, a storage unit 15, a temperature detection unit 16, and an update unit 17.

[0021] The high-frequency signal supply unit 11 supplies a high-frequency signal to the secondary battery 20. The impedance detection unit 12 detects the value of the real part Z of the AC impedance from the secondary battery 20 to which the high-frequency signal has been supplied.

[0022] Incidentally, in the secondary battery 20, metallic Li is deposited on the electrode surface of each battery cell as charging is repeated. Li deposition progresses as the charging power is increased to speed up the charging process, degrading the State of Health (SOH) of the secondary battery 20. The SOH of the secondary battery 20 is the ratio of the current capacity to the initial capacity of the secondary battery 20, which is set to 100%. Therefore, it is desirable to set the allowable charging power Pa of the secondary battery 20 to be as high as possible, which allows for efficient charging in the shortest possible charging time while suppressing Li deposition.

[0023] Here, if an AC signal (high-frequency signal) with a frequency too high for the diffusion, reaction, and movement of lithium ions in each cell of the secondary battery 20 is supplied to the secondary battery 20, the current of the high-frequency signal flows along the edges of the conductors of each cell due to the skin effect. In other words, the current of the high-frequency signal flows along the electrode surface of each cell where Li is easily deposited due to the skin effect. Furthermore, even when the Li metal is electrically disconnected from the negative electrode and becomes a floating state after Li deposition, current flows over the Li metal due to inductive coupling and electric field coupling. Therefore, the value of the real part Z of the AC impedance does not change when no Li is deposited compared to the initial state, and as the amount of Li deposition increases, the electrical conductivity of the electrode surface of each cell increases, so the value of the real part Z of the AC impedance decreases. Here, since a lot of current concentrates in the highly conductive Li metal, the magnetic field changes around the Li deposition region, and eddy currents are generated as a result. These eddy currents cause losses in the current collector foil and the conductive parts of the electrodes, but reduce the overall loss of the battery. Therefore, as the amount of Li deposited increases, the change in the magnetic field becomes larger, and consequently the eddy currents increase, resulting in a smaller value for the real part Z. For this reason, the amount of Li deposited in the secondary battery 20 can be calculated from the value of the real part Z of the AC impedance detected from the secondary battery 20 to which a high-frequency signal is supplied. Once the amount of Li deposited is known, it is also possible to estimate the SOH of the secondary battery 20.

[0024] Figure 2 shows the relationship between the State of Health (SOH) of the secondary battery 20 and the change in the real part Z of the AC impedance (the difference between the detected value and the initial value) when a 1 MHz high-frequency signal is supplied to the secondary battery 20. As indicated by the triangles in Figure 2, in the case of normal charging with low charging power, even if charging is repeated, the amount of Li deposition is small, so even if the deterioration of SOH progresses due to other factors, the change in the real part Z of the AC impedance remains small (i.e., the detected value of the real part Z of the AC impedance is maintained at a high value). In contrast, as indicated by the circles in Figure 2, in the case of rapid charging with high charging power, the amount of Li deposition increases with repeated charging, and consequently, the deterioration of SOH progresses, and the change in the real part Z of the AC impedance becomes large (i.e., the detected value of the real part Z of the AC impedance becomes low). Note that if battery degradation due to Li deposition is the dominant factor among the factors of battery degradation, the amount of Li deposition can be derived from SOH. Alternatively, SOH can be derived from the amount of Li deposition.

[0025] Figures 3 and 4 show the relationship between the frequency of the AC signal supplied to the secondary battery 20 and the real part of the AC impedance detected from the secondary battery 20. Figure 3 shows the value of the real part Z of the AC impedance when an AC signal from 1 kHz to 100 kHz is supplied to the secondary battery 20. Figure 4 shows the value of the real part Z of the AC impedance when an AC signal from 100 kHz to 100 MHz is supplied to the secondary battery 20.

[0026] As shown in Figure 3, when an AC signal near 1 kHz is supplied to the secondary battery 20, the real part Z of the AC impedance is at its minimum value. The impedance component at this time represents the ohmic resistance component. Furthermore, as shown in Figures 3 and 4, as the frequency of the AC signal supplied to the secondary battery 20 increases, the real part Z of the AC impedance increases because the current flow concentrates on the electrode surface of each cell due to the skin effect.

[0027] Therefore, the high-frequency signal supply unit 11 supplies a high-frequency AC signal (i.e., a high-frequency signal) having a real part Z of the AC impedance that is sufficiently higher than the ohmic resistance component to the secondary battery 20. For example, the high-frequency signal supply unit 11 supplies a high-frequency signal of 0.1 MHz or higher to the secondary battery 20. In the examples of FIGS. 3 and 4, the high-frequency signal supply unit 11 supplies a high-frequency signal of 0.5 MHz or higher to the secondary battery 20. Thereby, the current of the high-frequency signal flows on the electrode surface (Li deposition region) of each battery cell of the secondary battery 20 due to the skin effect. Thereby, the impedance detection unit 12 can detect the real part Z of the AC impedance corresponding to the Li deposition amount.

[0028] The determination unit 13 determines whether Li has been deposited in the secondary battery 20 from the value of the real part Z of the AC impedance detected by the impedance detection unit 12. More specifically, the determination unit 13 determines the presence or absence of Li deposition in the secondary battery 20 based on the difference between the current value of the real part Z of the AC impedance detected by the impedance detection unit 12 and the initial value of the real part Z of the AC impedance of the secondary battery 20. Information on the initial value of the real part Z of the AC impedance of the secondary battery 20 to be managed is stored in, for example, the storage unit 15. The determination unit 13 may, for example, subtract the value of the real part Z of the AC impedance from the initial value, and if the subtraction result is greater than the threshold value, determine that more Li has been deposited in the secondary battery. The determination unit 13 may perform another operation (for example, calculation of a ratio, etc.) different from subtraction on the initial value and the value of the real part Z of the AC impedance.

[0029] Note that the storage unit 15 may store information on the initial value of the real part Z of the AC impedance of each type of secondary battery. Further, the storage unit 15 may store parameters for determining the allowable input current value I lim [t] described later.

[0030] The temperature detection unit 16 detects the battery temperature of the secondary battery 20. For example, the temperature detection unit 16 detects the battery temperature of one or more of the multiple battery cells constituting the secondary battery 20 using one or more thermistors T1. The temperature detection unit 16 may also calculate the resistance value of each of the multiple battery cells from the cell voltage of each of the multiple battery cells. Then, the temperature detection unit 16 may calculate the difference between the heat generated by each of the multiple battery cells and the heat generated by the battery cell to which the thermistor T1 is attached, from the difference between the calculated resistance values ​​of each of the multiple battery cells and the resistance value of the battery cell to which the thermistor T1 is attached, and estimate the temperature of each of the multiple battery cells from the calculation result.

[0031] The control unit 14 controls the allowable charging power Pa for the secondary battery 20 based on the determination result from the determination unit 13. For example, if the control unit 14 determines that no Li has been deposited, it may maintain the allowable charging power Pa at its current level or increase it, since the progression of Li deposition is being suppressed. If the control unit 14 determines that Li has been deposited, it is necessary to suppress the progression of Li deposition, so it controls the allowable charging power Pa to decrease. The control unit 14 may also switch the allowable charging power Pa in stages depending on whether or not Li deposition has occurred.

[0032] As a result, the battery management device 10 according to this disclosure can set the highest possible allowable charging power Pa for the secondary battery 20, enabling efficient charging in the shortest possible charging time while suppressing Li deposition. In other words, the battery management device 10 according to this disclosure can set the allowable charging power Pa for the secondary battery 20 to an appropriate value according to the amount of Li deposition, without setting it excessively low, thereby enabling efficient charging of the secondary battery 20.

[0033] The control of the allowable charging power Pa by the control unit 14 will be explained in more detail. First, the control unit 14 uses equation (1), etc., to determine the allowable input current value I to the secondary battery 20. lim [t] is the previously calculated allowable input current value I lim Calculated based on [t-1].

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[0034] In the formula, IB[t] represents the value of the charging current at time t. TB[t] represents the value of the battery temperature at time t. SOC[t] represents the State of Charge (SOC) value at time t. The f() function represents the allowable current reduction term per unit time. The allowable current reduction term is calculated based on the allowable input current value I, depending on the value of the charging current. lim The limit on [t] is strengthened. The g() function represents the allowable current recovery term per unit time due to inactivity. The allowable current recovery term relaxes the limit on the allowable input current value over time. dt represents unit time. α is a parameter that represents the effect of the allowable current reduction term and is also called the first parameter. β is a parameter that represents the effect of the allowable current recovery term and is also called the second parameter. Note that in the equation, I lim [t] and IB[t] may be defined to take negative values. lim [0] indicates the maximum current value at which Li does not precipitate within a unit time when charging from a state unaffected by charge / discharge history. lim [0] can also be treated as a parameter. Note that α, β, I lim Parameters such as [0] may be defined for each battery temperature and each SOC.

[0035] The control unit 14 sets the allowable input current value I lim Input power limit W based on [t] IN By controlling the charging with [t], the charging current is set to the allowable input current value I lim By setting the [t] value below this, the deposition of Li can be suppressed. Note that the allowable input current value I lim [t] calculation method, allowable input current value I lim [t] Input power limit value W IN Method for converting to (t), and input power limit value W. IN The charging control method based on (t) is not particularly limited, and various known methods can be applied.

[0036] If the control unit 14 determines, for example, that no Li has precipitated, it sets the allowable charging power Pa to the input power limit value W. IN (t) may also be set. Furthermore, if the control unit 14 determines that Li has precipitated, it sets the allowable charging power Pa to the input power limit value W. IN You may set it to a value lower than (t).

[0037] The update unit 17, based on the charging pattern determined by the determination unit 13 when Li has been deposited, determines the above-mentioned allowable input current value I lim Parameters for determining [t] (e.g., first parameter α, second parameter β, I lim [0]) is updated. The charging pattern is information indicating the charging current and charging time of the secondary battery 20, and may be, for example, information indicating the change in the value of the charging current over time, or it may be frequency information of the value of the charging current per unit time. The charging pattern may also include information on the battery temperature and SOC of the secondary battery 20. The update unit 17 may, for example, set a large value of α at a specific battery temperature if Li is deposited at that specific temperature.

[0038] The update unit 17, when Li precipitates, adjusts the allowable input current value I lim The parameters for determining [t] are updated to suppress the precipitation of Li. For example, when using equation (1), increase α, decrease β, I lim By reducing [0] or its absolute value, or a combination thereof, the deposition of Li can be suppressed. Specifically, the update unit 17 collects the charging pattern when Li is deposited and prevents the deposition of Li while adjusting the allowable input current value I lim To make [t] larger, α, β, and I lim[0] is optimized by fitting, etc. As a criterion for updating the parameters, for example, if Li is deposited when the value of the charging current in the charging pattern is relatively large, it is conceivable to update α to a larger value. When the value of the charging current is relatively large, this includes when the absolute value of the charging current is greater than the threshold. Also, for example, if Li is deposited when the charging time in the charging pattern is relatively long and the value of the charging current is relatively small, it is conceivable to update β to a smaller value. When the charging time is relatively short, this includes when the value of the charging time is less than the threshold. In this way, the update unit 17 can appropriately update the parameters based on the charging pattern. The updated parameters may be used for charging control of the secondary battery 20 to be operated in the future.

[0039] As a result, the battery management device 10 according to this disclosure can set the highest possible allowable charging power Pa that allows for efficient charging in the shortest possible charging time while suppressing Li deposition. In addition, the battery management device 10 can set the allowable input current value I lim By updating the parameter for determining [t] to an appropriate value, Li precipitation can be further suppressed.

[0040] (Operation of battery management device 10) Next, an example of the operation of the battery management device 10 will be explained using Figure 5. Figure 5 is a flowchart showing the operation of the battery management device 10.

[0041] First, the battery management device 10 supplies the secondary battery 20 with an AC signal (high-frequency signal) of such a high frequency that the diffusion, reaction, and movement of lithium ions in each battery cell cannot keep up (step S101). For example, the battery management device 10 supplies the secondary battery 20 with a high-frequency signal of 0.1 MHz or higher. Then, the battery management device 10 detects the value of the real part Z of the AC impedance from the secondary battery 20 to which the high-frequency signal has been supplied (step S102).

[0042] Subsequently, the battery management device 10 determines whether or not Li has been deposited in the secondary battery 20 based on the detected value of the real part Z of the AC impedance (step S103).

[0043] If Li is deposited in the secondary battery 20 (YES in step S103), the battery management device 10 needs to suppress the progression of Li deposition, and therefore controls the allowable charging power Pa to be lowered (step S104). Subsequently, the battery management device 10 sets the allowable input current value I based on the charging pattern of the secondary battery 20. lim Update the parameters for determining [t] (step S105).

[0044] If Li has not deposited in the secondary battery 20 (NO in step S103), the battery management device 10 maintains the allowable charging power Pa as it is. Alternatively, the battery management device 10 may control the allowable charging power Pa to increase.

[0045] <Modification 1 of Embodiment 1> The determination unit 13 of the battery management device 10 determines the allowable input current value I lim In order to set the parameters for determining [t], it may be determined whether or not Li is deposited while changing the charging pattern in various ways. As a result, the update unit 17 determines the allowable input current value I lim The parameters for determining [t] can be automatically set to appropriate values.

[0046] <Modification 2 of Embodiment 1> Figure 6 is a block diagram showing an example configuration of a battery management device 10 according to a modified example 2 of Embodiment 1. The battery management device 10 shown in Figure 6 comprises a battery management terminal 30 and a server 40, with the update unit 17 provided on the server 40. The battery management terminal 30 is equipped with a communication unit 31, and the server 40 is equipped with a communication unit 41. The communication units 31 and 41 perform processing necessary for communicating with other devices via a network. The communication units 31 and 41 may include communication ports, routers, firewalls, etc. The secondary battery 20 may be mounted in the vehicle.

[0047] The determination unit 13 of the battery management terminal 30 transmits the charging pattern of the secondary battery 20 to the server 40 via the communication unit 31 if Li is deposited. The server 40 collects the charging patterns when Li is deposited from the battery management terminal 30 installed in each vehicle. The update unit 17 of the server 40 determines the allowable input current value I based on the collected charging patterns. lim The parameters for determining [t] are updated. The update unit 17 of the server 40 then distributes the updated parameters to multiple battery management terminals 30. Alternatively, the updated parameters are used for charging control of the secondary battery 20 to be installed in the next vehicle model.

[0048] Thus, the battery management device 10 according to the modified example 2 of Embodiment 1 collects information on the charging pattern when Li is deposited, and the allowable input current value I lim The parameters used to determine [t] can be set to more appropriate values.

[0049] Furthermore, this disclosure can be realized by having a Central Processing Unit (CPU) execute a computer program to perform some or all of the processing of the battery management device 10.

[0050] The program described above includes, when loaded into a computer, a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include Random-Access Memory (RAM), Read-Only Memory (ROM), flash memory, Solid-State Drive (SSD), or other memory technologies, CD-ROM, Digital Versatile Disc (DVD), Blu-ray® disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals.

[0051] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate. [Explanation of symbols]

[0052] 1. Battery Management System 10 Battery management device 11. High-frequency signal supply unit 12 Impedance detection unit 13 Judgment section 14 Control Unit 15 Storage section 16 Temperature detection unit 17 Update section 20 Secondary battery 30 Battery management terminal 31, 41 Communications Department 40 servers

Claims

1. A high-frequency signal supply unit that supplies high-frequency signals of 0.1 MHz or higher to a lithium-ion secondary battery, An impedance detection unit for detecting the actual AC impedance of the lithium-ion secondary battery to which the high-frequency signal is supplied, A determination unit that determines whether or not Li has been deposited in the lithium-ion secondary battery based on the actual AC impedance of the lithium-ion secondary battery, An update unit updates parameters for determining the allowable input current value to the lithium-ion secondary battery based on the charging pattern of the lithium-ion secondary battery when Li is deposited. A battery management device equipped with the following features.

2. The update unit collects the charging pattern when Li is deposited from each vehicle equipped with the lithium-ion secondary battery, and updates the parameters based on the collected charging pattern. The battery management device according to claim 1.

3. The determination unit repeatedly determines whether or not Li has precipitated while changing the charging pattern. The battery management device according to claim 1 or 2.

4. The aforementioned parameters include a first parameter that represents the effect of a term that strengthens the limit on the allowable input current value depending on the value of the charging current flowing through the lithium-ion secondary battery. The battery management device according to claim 1 or 2.

5. The aforementioned parameter includes a second parameter that represents the effect of a term that relaxes the limit on the allowable input current value over time. The battery management device according to claim 4.

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