TW202411680A - Battery management device, battery management method, battery management program - Google Patents

Abstract

[Topic] To provide a technology that can accurately estimate the degree of battery wear in a short time. [Solution] The battery management device of the present invention estimates the degradation mode of the battery based on the change in battery voltage over time during the battery's rest period, selects the Eyring plot corresponding to the estimated degradation mode, and diagnoses the state of the battery based on the selected plot.

Description

Battery management device, battery management method, battery management program

The present invention relates to a technology for managing the state of a battery.

The degree of degradation of secondary batteries varies depending on the surrounding environment, C-rate, charging and discharging methods, etc. However, the general battery diagnosis method only uses the current state of the battery to diagnose the degradation state (State Of Health: SOH), so there is a possibility of errors in the prediction results that cannot be ignored.

The following patent document 1 is entitled "Providing a battery management system, a battery information server, a charge and discharge control device, and a battery for accurately predicting the life of a secondary battery as much as possible, preventing accidents in advance, and correctly using up the secondary battery", and states that "a unique LIBID is assigned to a LIB, and the activation state of the LIB is recorded in a log table (log table) and the LIB usage record table is collected in the LIB information server. Then, the cumulative failure probability is calculated based on the huge LIB usage record table, and the cumulative failure probability table is prepared. The charge and discharge control device is a technology that calculates the "optimal replacement period of the LIB" based on the cumulative failure probability table received from the LIB information server via the LIB, the storage time slope function, the loss cost function, the replacement cost function, the warning limit value, and the use prohibition limit value (see abstract).

The following patent document 2 is titled "Providing a calculation method, calculation program, calculation system, and calculation device for calculating the internal state of a secondary battery with good accuracy", and describes the technology of "In a calculation device 10 having a calculation processing unit 100 for calculating the internal state of a secondary battery BT, the voltage and current of the secondary battery BT are read from the memory unit 160, and three or more characteristic parameters that are not subordinate to each other, including a constant term near the intermediate value of charge and discharge, a molar term near the limit value, and a charge and discharge limit value included in the characteristic formula P of the secondary battery BT are calculated, and the internal state of the secondary battery is calculated using the calculated characteristic parameters, and the calculation method is implemented by storing the calculated internal state in the memory unit 160" (see abstract). [Prior art literature] [Patent literature]

[Patent Document 1] Japanese Patent Publication No. 2017-034781 [Patent Document 2] Japanese Patent Publication No. 2013-167568

(Invent the problem you want to solve)

When estimating the remaining life of a battery, it is extremely useful to estimate the degree of battery depletion. In the known battery diagnosis such as patent documents 1-2, a battery with a large decrease in SOH is generally judged to be in a depleted state as a relative evaluation. However, there are various reasons for the decrease in SOH, and a battery with a low SOH is not necessarily in a depleted state. In addition, it is desirable to shorten the time required for diagnosing the remaining life as much as possible.

This invention was made in view of the above-mentioned problem, and its purpose is to provide a technology that can accurately estimate the degree of battery consumption in a short time. (Technical means to solve the problem)

The battery management device of the present invention estimates the degradation mode of the battery based on the change in battery voltage over time during the rest period of the battery, selects the Eyring plot corresponding to the estimated degradation mode, and diagnoses the state of the battery based on the selected plot. (Effect of the invention)

The battery management device of the present invention can accurately estimate the degree of battery consumption in a short time. Other topics, structures, effects, etc. of the present invention are clearly understood from the following description of the embodiments.

＜Implementation form 1＞

Fig. 1 is a schematic diagram showing an example of the configuration of a storage battery system. The storage battery system is composed of a battery system composed of one or more storage batteries and a battery management device that manages the battery system. In the following, it is assumed that the storage battery is used as the battery.

The battery system has a battery module. The battery module is composed of one or more sub-modules. The sub-module has: a battery cell, and a sensor group. The sensor group is, for example, a voltage sensor for measuring the output voltage of the battery cell, a temperature sensor for measuring the temperature of the battery cell, an inductive sensor for measuring the output current of the battery cell, etc. The temperature sensor can be composed of, for example, a thermocouple. The sensing unit obtains the measurement result from the sensor and sends a signal to the battery management module (BMU). The BMU outputs measurement data recording the measurement result to the battery management device.

The battery management device is equipped with: a sensor unit for obtaining measurement data, a calculation unit for managing the battery status, a memory unit for storing data, etc. The calculation unit uses the measurement data obtained by the BMU to estimate the battery status. For example, as described below, the remaining life of the battery can be estimated (or the degree of depletion used to estimate the remaining life).

FIG2 shows the time variation of the battery voltage during the rest period after the charging or discharging operation. Here, the battery voltage after the discharging operation is shown as an example, but the same time variation can be observed after the charging operation. The battery voltage during the rest period has: a voltage variation component ΔVa in the first period (time length Δt1) which is a relatively early stage, and a voltage variation component ΔVb in the second period (time length Δt2) which is a relatively late stage. ΔVa is a response component obtained by a component with a small time constant of the equivalent circuit of the battery, such as the response obtained by the internal resistance or the negative electrode. ΔVb is the response component obtained by the components of the battery's equivalent circuit with a large time constant, such as the response obtained by the positive electrode or diffusion resistance.

According to the results of the research conducted by the inventors, it is known that the ratio between ΔVa and ΔVb corresponds to the degradation pattern (degradation rate) of the battery. Therefore, in the present invention, the degradation pattern is estimated using ΔVa and ΔVb (or their time variation rates) in the following order, and the Eyring plot corresponding to the degradation pattern is used to estimate the battery's wear state.

FIG3 is a graph showing the relationship between ΔVa and ΔVb. For a battery with a slow deterioration rate, if ΔVa and ΔVb are plotted as shown in FIG3, the plots are gathered near a certain critical value. In contrast, for a battery with a fast deterioration rate, the inventors have found that the plots exist in a region above the critical value. Therefore, in the present invention, it is estimated that the battery is deteriorating in a fast or slow deterioration rate mode based on whether the plots are above the critical value.

The plot of ΔVa and ΔVb may be either the upper or lower part of FIG3. That is, the horizontal axis may be set to ΔVb/Δt2, and the vertical axis may be set to either (ΔVa/Δt1)/(ΔVb/Δt2) or ΔVa/Δt1. In any plot, the plot of the battery with a high degradation rate is also plotted in the area exceeding the critical value of the vertical axis as shown by the black circle in FIG3. That is, for the battery with a plot exceeding the critical value on the vertical axis of FIG3, it can be determined that the degradation rate is high.

FIG4 is a schematic diagram showing an example of selecting an Eyring plot corresponding to a degradation pattern of a battery. The memory unit of the battery management device stores data describing the Eyring plot according to the degradation pattern (degradation rate) of each battery. The calculation unit estimates the degradation rate of the battery and selects the Eyring plot corresponding to the degradation rate from the data. The calculation unit estimates the degree of battery wear using the Eyring plot in the sequence described below.

The Eyring plot stored in the memory is prepared in advance. The slope of the Eyring plot can be determined based on, for example, the activation energy of the battery. The intercept of the Eyring plot can be determined based on, for example, the SOH of the battery. In addition, there are cases where the Eyring plot is different depending on which plot is used, the upper and lower plots of FIG. 3 , so the Eyring plots corresponding to the vertical axis of FIG. 3 can also be prepared in advance.

FIG5 is a flowchart illustrating the sequence of estimating the degradation rate. The calculation unit of the battery management device obtains data recording the measurement results of ΔVa and ΔVb from, for example, the BMU. The calculation unit plots these as shown in FIG3. If the plot exceeds the critical value, the degradation rate of the battery is estimated to be A (relatively large), and if it is below the critical value, the degradation rate is estimated to be B (relatively small). In addition, the lower limit value and the plot can also be compared. At this time, it is estimated that the degradation rate is which of A to C (relatively minimum).

FIG6 is a schematic diagram showing the sequence of determining the degree of battery wear using the battery state and the Eyring plot. Based on the battery measurement results, a plot corresponding to the vertical axis and horizontal axis of the Eyring plot is obtained. By comparing this plot with the Eyring plot selected in FIG5, the degree of battery wear is estimated.

If the plot obtained from the battery measurement results is on the Erling plot (or within a predetermined range of dots near the Erling plot) (Figure 6(i)), the battery is estimated to be not in a worn-out state (normal state). If the plot obtained from the battery measurement results is not within the predetermined range (Figure 6(ii)), the battery is estimated to be not in a worn-out state, but if the current operating state continues, deterioration will progress. At this time, as described later, the battery operating conditions can also be adjusted. If the plot obtained from the battery measurement results deviates further from the predetermined range (Figure 6(iii)), the battery is estimated to be worn-out.

The intercept of the Eyring plot corresponds to the SOH, so the upper and lower limits of the range in which the battery is considered normal on the Eyring plot can also be set according to the upper and lower limits of the SOH. However, if a battery with a significantly reduced SOH is plotted on the Eyring plot, it may be within the normal range. This is considered to be due to the reduction in SOH due to reasons other than wear and tear. That is, as a result of the review conducted by the inventors, it was found that it is inappropriate to use only SOH to determine whether it is a worn state. Therefore, in the present invention, whether it is a worn state is determined based on the degree of deviation from the normal range on the Eyring plot.

For example, if the distance from the normal range (the range assigned to the dots) to the plotted point in the two-dimensional coordinate space of FIG. 6 is greater than the first critical value, the battery is judged to be in the state of FIG. 6 (iii) (a worn-out state). If the distance from the normal range to the plotted point is less than the first critical value and greater than the second critical value (the second critical value ≦ distance < the first critical value), the battery is judged to be in the state of FIG. 6 (ii) (a state in which degradation will progress if used directly).

FIG7 is a diagram illustrating the procedure for finding the current cycle number of a battery. When making an Eyring plot or plotting the actual measurement results of a battery on the Eyring plot, the number of charge and discharge cycles (current cycle number) implemented by the battery so far must be found. Therefore, in the present invention, the current cycle number is found by the following procedure.

The SOH of a battery is defined by, for example, the discharge current from full charge to complete discharge. At this time, the SOH can be defined by the absolute value of the discharge current. The relationship between the discharge current and the number of cycles is as shown in the lower part of Figure 7. That is, for a normal battery, the discharge current is not easy to decrease even if the number of cycles increases. In contrast, for a battery that is progressing in deterioration, the discharge current decreases as the number of cycles increases.

From the relationship in the lower part of Figure 7, it can be seen that the greater the reduction in discharge current, the more advanced the degradation. In this way, the current cycle number can be expressed as a function that is proportional to the inverse of the reduction in discharge current from the normal state (capacitance decay amount). In other words, the following formula holds: Current cycle number = a/capacitance decay amount + b. The value of the vertical axis when the current state of the battery is plotted on the Eyring plot (i.e., the value of the vertical axis of the white circle in Figure 7) can be obtained using this formula.

FIG8 is a flowchart for explaining the operation of the battery management device in the first embodiment. This flowchart can be implemented by the calculation unit of the battery management device. This flowchart determines the degree of battery wear based on the principle described above. The following describes each step of FIG8.

The calculation unit obtains ΔVa and ΔVb shown in FIG2 from, for example, the BMU. The calculation unit also obtains the battery state of charge (SOC), battery temperature, battery current, etc. from, for example, a measuring device. The sources of obtaining these measurement data are not limited to the above.

The calculation unit estimates the degradation rate of the battery by the method described in FIGS. 3 to 5 and selects the Eyring plot corresponding to the estimated degradation rate. The data describing the Eyring plot is pre-stored in the memory unit of the battery management device. More specifically, the slope of the Eyring plot corresponds to the degradation pattern, so the degradation pattern is estimated by the method described in FIGS. 3 to 5 and the slope corresponding to the degradation pattern is specified.

The calculation unit obtains the result of measuring or estimating the SOH of the battery. The SOH can be estimated by referring to data that describes the corresponding relationship between ΔVa, ΔVb, their time change rates, and SOH, as described in FIG. 2, for example. Alternatively, the measurement result of the SOH can be obtained from an external device such as a BMU. The SOH corresponds to the intercept of the Eyring plot. By specifying the slope and intercept of the Eyring plot, the calculation unit can select the Eyring plot corresponding to the degradation mode.

The calculation unit plots the current state of the battery on the selected Eyring plot. Specifically, the difference between the current temperature of the battery and the standard temperature is set as ΔT, and the current number of cycles obtained by the method described in FIG. 7 is set as N and plotted on the Eyring plot. The calculation unit also estimates the degree of battery wear based on the distance between the Eyring plot and the plot of the current state of the battery according to the method described in FIG. 6.

FIG9 is a flowchart for explaining other operations of the battery management device. In addition to the flowchart of FIG8, the calculation unit may also determine whether to use an application method for suppressing the progress of battery degradation (degradation mitigation operation mode). For example, if the battery wear level is equivalent to the middle section of FIG6, consider using an application method for suppressing the progress of degradation to suppress further degradation. If the wear level is the upper section of FIG6, it is sufficient to continue normal operation. If the wear level is the lower section of FIG6, consider outputting an alarm urging replacement, for example.

As an example of a method for suppressing the progression of battery degradation, consider setting at least one of the following restrictions: setting at least one of an upper limit or a lower limit for the battery voltage; setting an allowable range for the battery temperature; or setting at least one of an upper limit or a lower limit for the SOC.

Figure 10 shows the change in battery status caused by the use of a method for suppressing the progress of battery degradation. If the current battery status is beyond the Erling plot (upper part of Figure 10), the battery status is on the Erling plot (or within a predetermined range near the Erling plot) by using a method for suppressing the progress of battery degradation. This can suppress further degradation of the battery and extend the remaining life.

Fig. 11 is an example of a data table showing the results of battery diagnosis by the battery management device. The battery management device may also record the measurement data obtained by the BMU, etc., the degree of wear (whether to change the operation method) determined by the flowchart of Fig. 9, etc. for each diagnosed battery in the data table and store them in the memory unit.

FIG. 12 is a configuration diagram of a battery system 1. The battery system 1, the battery controller (BMU) 12, and the battery management device 13 are illustrated in FIG. 1 . The battery system 1 comprises: an upper controller 11, a battery controller (BMU) 12, and a battery management device 13. The upper controller 11 outputs an action instruction to the battery through the battery controller 12. The battery controller 12 controls the battery module according to the instruction. The battery management device 13 comprises: a sensing unit 131 that obtains measurement data from the battery controller 12, an operation unit 132 that diagnoses the battery according to the method described above, and a memory unit 133 that stores data used by the operation unit 132.

FIG. 13A and FIG. 13B are examples of user interfaces provided by the battery management device. The user interface can display measurement data obtained during the implementation of the flowchart of FIG. 9, etc. It can also display the time-dependent change of the battery voltage as described in FIG. 3, the critical value when calculating the degradation rate as described in FIG. 4, etc. It can also display the Weber distribution described later.

<Implementation Form 2> If a battery system is composed of a plurality of batteries, there is a case where the degree of depletion of the battery system as a whole needs to be determined. In this case, as in Implementation Form 1, the degree of depletion of the battery system as a whole can be determined by plotting the current state of each battery on the Eyring plot. Therefore, in Implementation Form 2 of the present invention, an example of the operation of a battery management device for diagnosing the state of the battery system as a whole is described. The configuration of the battery system and the battery management device is the same as that of Implementation Form 1.

FIG. 14 is a diagram showing the result of plotting the current status of a plurality of batteries on the Eyring plot. If, for example, the number of batteries that deviate from the Eyring plot is relatively small as shown in the middle of FIG. 14, a method of suppressing the progress of degradation is adopted. If, as shown in the lower part of FIG. 14, the number of batteries that deviate greatly from the Eyring plot is large, the battery system as a whole is judged to be in a worn state. The following is an example of using the Weibull plot as a sequence for diagnosing the status of the battery system as a whole.

Fig. 15 is a schematic diagram showing the procedure for creating an Eyring plot for the entire battery system. The Eyring plot can be created for each battery, but since the battery system is composed of a plurality of batteries, the following procedure is used to create a single Eyring plot for the entire battery system.

The calculation unit obtains the measurement data of the battery voltage of each battery from, for example, the BMU, and selects the Eyring plot of each battery by the method described in the first embodiment. The calculation unit selects the Eyring plot as the entire battery system by specifying that all batteries of the battery system are within the normal range of the Eyring plot from among the Eyring plots. When determining the degree of wear of the entire battery system, the Eyring plot is used as a reference.

FIG. 16 is a histogram showing the result of counting the deviation between the critical value and the Eyring plot for each battery. By finding the deviation between the Eyring plot of the entire battery system and the critical value, the unevenness or outliers of the battery depletion can be grasped. The calculation unit uses the battery whose depletion represented by the histogram exceeds the Eyring plot of the entire system to create the Weber plot described below.

By using the statistical values shown in FIG16, it is possible to statistically calculate the critical value and the outliers with large deviation in the battery system. In particular, even for a battery that has a low SoH calculated using the discharge current and appears to be worn out at first glance, it can be judged that it is still usable in the battery system as a whole by using the Eyring plot. On the contrary, even for a battery that has a high SoH calculated using the discharge current and appears to be healthy at first glance, if it exceeds the normal range of the Eyring plot, it can be sensed as a sign related to wear.

FIG. 17 is a flowchart for explaining the operation of the battery management device of the second embodiment. The calculation unit plots the current battery measurement result on the Eyring plot as in the first embodiment. If the flowchart is implemented for the battery system, the Eyring plot is a single Eyring plot selected for the entire battery system as described in FIG. 16.

When the measurement results of each battery are plotted on the Eyring plot, the calculation unit specifies the plot that exceeds the normal range (i.e., the column corresponding to the right end in Figure 16). The calculation unit uses the measurement results of the battery that exceeds the normal range to create a Weber plot. For example, the logarithm of the time elapsed from the start of use is obtained as the horizontal axis, and the logarithm of the cumulative defective rate is obtained as the vertical axis. Whether a defective state has been reached can be determined by the value of SOH. By plotting the measurement results of the battery that exceeds the normal range on its two axes, a Weber plot can be obtained. The Weber plot has time-dependent elements such as the elapsed time and the so-called cumulative defective rate, so in this flowchart, it is noted that the measurement data of the battery obtained by the calculation unit is a time-dependent record.

The calculation unit calculates the shape parameter m of the Weber plot. For example, the shape parameter m can be obtained by finding the slope of the regression line of the plot that goes beyond the battery. If the shape parameter m of the Weber distribution exceeds 1, the calculation unit estimates that the battery system is in a depleted state. If m is less than 1, it is determined that it can be used within the appropriate range of action.

According to the second embodiment, even if the SOH of the battery system as a whole is deteriorating, it can be determined statistically that there will be no problem with the battery system as a whole if appropriate pressure is applied. If it is estimated that the battery system as a whole is deteriorating, the battery system operation conditions can be changed or the battery with the most deterioration can be replaced in the same manner as in FIG. 9.

<Implementation form 3> Figure 18 is a diagram showing an example of using the battery management device 13. The sensing unit 131 obtains the measured values or their records of the battery voltage, battery temperature, battery current, C-rate, SOC, etc. of each battery module (or battery cell) from the BMU, and records them in the memory unit 133. The calculation unit 132 can use the data to estimate the degree of battery consumption by the method described in the implementation form 1, and change the application method as needed (adopt an application method that can suppress degradation). In this way, the degradation of the battery can be suppressed.

For example, when the power generated by the power generation system including the battery system is transmitted to the power transmission network of the power company, it is considered that the power transmission plan is prepared in advance on the day before the power transmission and transmitted to the power company, and the degree of battery depletion is diagnosed in a short time before the power transmission starts on the power transmission implementation day. In the case shown above, the diagnosis method of the present invention is extremely useful in that the diagnosis can be completed in a short time.

FIG19 is a diagram showing another example of using the battery management device 13. The battery management device 13 is connected to a charger via a cloud system or the like. The charger is a device that charges a battery carried by a vehicle. The sensing unit 131 obtains measurement data such as the battery voltage or battery temperature of the battery carried by the vehicle through the charger (or through a meter connected to the vehicle). The calculation unit 132 can use the measurement data to diagnose the degree of battery depletion by the method described in the first embodiment.

FIG20 is a flowchart illustrating the processing performed by the battery management device 13 in the system configuration of FIG19. This flowchart can be implemented by the calculation unit 132. The sensing unit 131 obtains the measurement data of the battery from the BMU, etc. The calculation unit 132 plots the measurement results of each battery on the Eyring plot by the method described in the implementation form 1. The calculation unit 132 creates a Weber plot by the sequence described in the implementation form 2. The calculation unit 132 estimates the degree of battery depletion based on the shape parameter m of the Weber plot. For batteries that have not reached a depleted state but will progress in deterioration if directly used (the middle section of FIG6 and the middle section of FIG14), the method of use is changed to suppress the progress of degradation. For batteries that have reached a worn-out state (lower section of FIG. 6 and lower section of FIG. 14 ), the time until the batteries become unusable can also be estimated.

<About variations of the present invention> The present invention includes various variations and is not limited to the aforementioned embodiments. For example, the aforementioned embodiments are described in detail to facilitate understanding of the present invention and are not necessarily limited to the embodiments having all the described structures. In addition, a part of the structure of a certain embodiment may be replaced with the structure of another embodiment, and a structure of another embodiment may be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures may be added/deleted/replaced.

In the above embodiment, the start time of ΔVb is later than the start time of ΔVa, and the end time of ΔVb is later than the end time of ΔVa. As long as this relationship is maintained, for example, Δt1 (first period) and Δt2 (second period) may partially overlap.

In the above embodiments, the sensing unit 131 and the computing unit 132 may be formed by hardware such as circuit elements having the functions thereof, or by a computing device such as a CPU (Central Processing Unit) executing software having the functions thereof.

1: Battery system 11: Host controller 12: Battery management unit (BMU) 13: Battery management unit 131: Sensor unit 132: Calculation unit 133: Memory unit

[FIG. 1] is a schematic diagram showing an example of the configuration of a battery system. [FIG. 2] is a diagram showing the change over time of the battery voltage during the rest period after a charging operation or a discharging operation. [FIG. 3] is a graph showing the relationship between ΔVa and ΔVb. [FIG. 4] is a schematic diagram showing an example of an Eyring plot corresponding to a selected battery degradation mode. [FIG. 5] is a flowchart illustrating a procedure for estimating a degradation rate. [FIG. 6] is a schematic diagram showing a procedure for determining a battery depletion degree using a battery state and an Eyring plot. [FIG. 7] is a diagram illustrating a procedure for determining the current number of cycles of a battery. [FIG. 8] is a flowchart illustrating the operation of a battery management device in Embodiment 1. [FIG. 9] is a flowchart illustrating other operations of the battery management device. [FIG. 10] is a diagram showing changes in battery status caused by adopting an application method for suppressing the progress of battery degradation. [FIG. 11] is an example of a data table recording the results of battery diagnosis by a battery management device. [FIG. 12] is a diagram showing the configuration of a battery system 1. [FIG. 13A] is an example of a user interface provided by a battery management device. [FIG. 13B] is an example of a user interface provided by a battery management device. [FIG. 14] is a diagram showing the result of plotting the current status of a plurality of batteries on an Eyring plot. [FIG. 15] is a diagram showing a pattern of the order of creating an Eyring plot for the entire battery system. [FIG. 16] is a histogram recording the result of counting the degree of deviation between a critical value and an Eyring plot for each individual battery. [Figure 17] is a flowchart for explaining the operation of the battery management device of the second embodiment. [Figure 18] is a diagram showing an example of the operation of the battery management device 13. [Figure 19] is a diagram showing other examples of the operation of the battery management device 13. [Figure 20] is a flowchart for explaining the processing performed by the battery management device 13 in the system configuration of Figure 19.

Claims (15)

A battery management device is a battery management device for managing the state of a battery, characterized by: It has: A sensing unit for obtaining a detection value of a voltage outputted by the battery; A memory unit for storing data describing the Eyring plot of the battery according to the degradation mode of each battery; An operation unit for estimating the state of the battery; The operation unit estimates the degradation mode of the battery based on the change in the voltage over time during the rest period after the battery has finished charging or discharging; The operation unit selects the Eyring plot corresponding to the estimated degradation mode; The operation unit diagnoses the state of the battery based on the selected plot. A battery management device as claimed in claim 1, wherein the calculation unit diagnoses the state of the battery based on the selected Eyring plot and the deviation between the plotted points when the measured values of the battery are plotted in the same coordinate space as the Eyring plot. As in the battery management device of claim 2, the calculation unit calculates the distance between the selected Eyring plot and the measured value in the coordinate space as the deviation, and the calculation unit diagnoses that the battery is depleted if the deviation is greater than the first critical value. A battery management device as claimed in claim 3, wherein the calculation unit controls the battery by operating the battery in a degradation mitigation operation mode for mitigating the progress of degradation of the battery if the deviation is less than the first critical value and greater than the second critical value. The battery management device of claim 4, wherein the degradation mitigation operation mode is at least one of the following: Setting an upper limit or lower limit of the voltage; Limiting the temperature range of the battery in such a way that the degradation rate of the battery is slower than before the degradation mitigation operation mode is started; Setting an upper limit or lower limit of the charging state of the battery. A battery management device as claimed in claim 4, wherein the degradation mitigation operation mode is configured to change the operation state of the battery in such a manner that the deviation does not reach the second critical value, thereby extending the remaining life of the battery. As in claim 2, the battery management device, wherein the calculation unit obtains the amount of decrease in the capacity of the battery due to one charging or discharging operation of the battery as the capacitance decay amount, the calculation unit calculates the number of charging or discharging cycles implemented by the battery according to a function proportional to the inverse of the capacitance decay amount, the calculation unit plots the number of cycles as the measured value on the coordinate space. The battery management device of claim 1, wherein the operation unit selects a single Eyring plot for a battery system composed of a plurality of batteries, the operation unit identifies, among the batteries constituting the battery system, batteries whose deviation from the Eyring plot is greater than a critical value as out-of-control batteries, the operation unit obtains a Weber plot of the cumulative failure rate of the out-of-control batteries and the operating time of the out-of-control batteries, the operation unit diagnoses the state of the battery system based on the shape parameters of the Weber plot. The battery management device of claim 1, wherein the battery is installed in a power intercommunication system for intercommunication between power transmission and distribution networks, the power intercommunication system comprises: a history storage unit for storing data recording the history of the voltage and the history of the charging state of the battery, the operation unit for obtaining the history of the voltage and the history of the charging state from the history storage unit, the operation unit for diagnosing the state of the battery using the history obtained, and controlling the operation conditions of the battery according to the result. As in claim 1, the battery management device, wherein the battery is mounted on an electric machine that uses the output from the battery as power to operate, and the calculation unit obtains the change in the voltage from the electric machine or a meter connected to the electric machine. As in claim 8, the battery management device, wherein the battery is mounted on an electric machine that uses the output from the battery as a power source to operate, the calculation unit obtains the change in the voltage from the electric machine or a meter connected to the electric machine, the calculation unit controls the operating conditions of the battery according to the shape parameter. As in claim 1, the battery management device, wherein the calculation unit determines the slope of the Eyring plot according to the activation energy of the battery, and the calculation unit selects the Eyring plot that determines the slope as the Eyring plot corresponding to the estimated degradation mode. As in claim 1, the battery management device, wherein the calculation unit determines the intercept of the Eyring plot according to the health status of the battery, and the calculation unit selects the Eyring plot that determines the intercept as the Eyring plot corresponding to the estimated degradation mode. A battery management method is a battery management method for managing the state of a battery, characterized by: having: a step of obtaining a detection value of a voltage output by the battery; a step of estimating the state of the battery using data in which an Eyring plot of the battery is recorded according to the degradation mode of each battery; in the estimating step, the degradation mode of the battery is estimated based on the change over time of the voltage during a rest period after the battery has finished a charging operation or a discharging operation; in the estimating step, the Eyring plot corresponding to the estimated degradation mode is selected; in the estimating step, the state of the battery is diagnosed based on the selected plot. A battery management program that causes a computer to execute a process for managing the state of a battery, characterized by: causing the aforementioned computer to execute the following steps: a step of obtaining a detection value of the voltage output by the aforementioned battery; a step of estimating the state of the aforementioned battery using data of the Eyring plot of the aforementioned battery recorded according to the degradation mode of each aforementioned battery; in the aforementioned estimating step, causing the aforementioned computer to execute a step of estimating the degradation mode of the aforementioned battery based on the time-dependent change of the aforementioned voltage during the rest period after the aforementioned battery has finished a charging operation or a discharging operation; in the aforementioned estimating step, causing the aforementioned computer to execute a step of selecting the aforementioned Eyring plot corresponding to the aforementioned estimated degradation mode; In the aforementioned estimation step, the aforementioned computer is caused to execute a step of diagnosing the state of the aforementioned battery based on the aforementioned selected plot.

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