Battery life estimation device and battery life estimation method

Abstract

To provide a storage battery life estimation device and a storage battery life estimation method with which the improvement of life estimation accuracy can be fully expected.SOLUTION: Calculation is carried out separately for a cycle time tcyc that pertains to a charge / discharge cycle in the operation period of a storage battery and a retention time tst that pertains to the elapse of retention. Next, an approximate expression of power law by a least squares approximation is acquired on the basis of the measured value of battery state of the storage battery, the cycle time tcyc, and the retention time tst. Then, calculation of life information (estimate cycle life tcyc_end, estimate life tsum_end, and residual total time tsum_rem, etc.) till the desired life of the storage battery is carried out on the basis of the acquired approximation expression.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to a battery life estimation device and a battery life estimation method. [Background technology]

[0002] The introduction of stationary battery storage systems is expanding, aimed at the effective use of renewable energy and power supply during disasters. Since the performance of battery storage systems gradually deteriorates, understanding the battery lifespan is crucial for the healthy operation of the system. Therefore, battery life estimation is being carried out.

[0003] One example of a battery life estimation technique is the use of the so-called square root rule, which utilizes the fact that the square root of the battery's operating time is proportional to the battery's capacity (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-254710 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, the battery life estimation technology described in Patent Document 1 aims to more accurately grasp the degradation of battery performance, particularly towards the end of its lifespan, based on the performance degradation status of the positive and negative electrodes of the battery. As this example shows, one of the requirements is to improve the accuracy of battery life estimation. The inventors of this invention were searching for a life estimation method different from the above improvement measures. [Means for solving the problem]

[0006] [1] A battery life estimation device that solves the above problems is a battery life estimation device that estimates the life of a battery based on an approximate formula obtained from measured values ​​of the battery state value of the battery, comprising: a period calculation unit that calculates the cycle time for charge-discharge cycles in which charge-discharge operations are performed during the operating period of the battery, and the storage time for storage periods in which no charge-discharge operations are performed; and a life estimation unit that obtains an approximate formula of a power law by least-squares approximation based on measured values ​​of the battery state value of the battery, the cycle time, and the storage time, and calculates life information up to the desired life of the battery based on the approximate formula.

[0007] According to the above configuration, the cycle time related to the charge-discharge cycle during the battery's operating period and the storage time related to the storage period are calculated separately. Next, an approximate formula using a power law based on the measured battery state value, cycle time, and storage time is obtained. Then, based on the obtained approximate formula, the lifespan information up to the desired lifespan of the battery is calculated. In other words, by focusing on the fact that the performance of the battery differs greatly between the charge-discharge cycle and the simple storage period, and performing calculations separately, a significant improvement in the accuracy of lifespan estimation can be expected. Furthermore, by using a power law for the approximation formula, it is possible to perform approximations other than the square root law, which is commonly used in battery lifespan estimation, depending on the situation. This also contributes to an improvement in the accuracy of lifespan estimation.

[0008] [2] The battery life estimation device described in [1] above is further comprising an estimation feasibility determination unit that determines whether the number of measured values ​​of the battery state of the battery is equal to or greater than a determination value for determining whether the number is sufficient for estimating the life of the battery, and permits the battery life estimation process, including the life estimation unit, based on the determination that it is equal to or greater than the determination value.

[0009] With the above configuration, battery life estimation is performed when there are a sufficient number of measured battery state values ​​that are above the judgment value. This is expected to further improve the accuracy of life estimation.

[0010] [3] In the battery life estimation device described in [1] or [2] above, the life estimation unit obtains an estimated value of the battery state value of the battery based on the approximation formula, and includes an estimation accuracy determination unit that determines whether the estimated value of the battery state value of the battery is in an approximation form in which the correlation coefficient with the measured value of the battery state value of the battery is equal to or greater than a determination value, and allows the battery life estimation process including the life estimation unit based on the determination that it is equal to or greater than the determination value.

[0011] According to the above configuration, battery life estimation is performed when the correlation coefficient between the estimated battery state value and the measured value is greater than or equal to a certain threshold. This further improves the accuracy of life estimation.

[0012] [4] In the battery life estimation device described in any one of [1] to [3] above, the life estimation unit obtains an estimated value of the battery state value of the battery based on the approximation formula, and is configured to obtain the approximation formula on the condition that the latest measured value of the battery state value of the battery matches the corresponding estimated value.

[0013] According to the above configuration, an approximation formula is obtained, including the condition that the latest measured battery state value of the storage battery matches the corresponding estimated value, and the storage battery's lifespan is estimated. Matching the latest measured value with the estimated value leads to an improvement in the accuracy of the lifespan estimation.

[0014] [5] In the battery life estimation device described in any one of [1] to [4] above, the life estimation unit is configured to acquire the approximate formula excluding the measured values ​​in the battery state value of the battery during the initial stages of operation.

[0015] According to the above configuration, the measured values ​​of the battery's state during the initial stages of operation are excluded, an approximate formula is obtained, and the battery's lifespan is estimated. Excluding older measured values ​​from the initial stages of operation leads to an improvement in the accuracy of the lifespan estimation.

[0016] [6] A battery life estimation method for solving the above problems is a battery life estimation method that estimates the life of a battery based on an approximate formula obtained from measured values ​​of the battery state value of the battery, and calculates the cycle time for charge-discharge cycles in which charge-discharge operations were performed during the operating period of the battery, and the storage time for storage in which no charge-discharge operations were performed, and obtains an approximate formula of a power law by least squares approximation based on the measured values ​​of the battery state value of the battery, the cycle time, and the storage time, and calculates life information up to the desired life of the battery based on the approximate formula.

[0017] With the above configuration, a significant improvement in the accuracy of battery life estimation can be expected, similar to the battery life estimation device described above. [Effects of the Invention]

[0018] According to the battery life estimation device and battery life estimation method of this disclosure, a significant improvement in life estimation accuracy can be expected. [Brief explanation of the drawing]

[0019] [Figure 1] This is a diagram showing the configuration of a storage battery and a lifespan estimation device in one embodiment. [Figure 2] This is a flowchart illustrating the battery life estimation process in the same embodiment. [Figure 3] This is an explanatory diagram relating to the estimation of the battery life in the same embodiment. [Figure 4] This is an explanatory diagram relating to the estimation of the battery life in the same embodiment. [Figure 5] This is an explanatory diagram regarding the estimation of battery life in the modified example. [Figure 6] This is an explanatory diagram regarding the estimation of battery life in a comparative example. [Modes for carrying out the invention]

[0020] Below, an embodiment of a battery life estimation device and a battery life estimation method will be described with reference to the drawings. (Overall configuration of the lifespan estimation device 20 for estimating the lifespan of the storage battery 10) Figure 1 shows the overall configuration of this embodiment, including the battery 10 and the life estimation device 20. The battery 10 is, for example, a stationary lithium-ion battery. The battery 10 is installed for purposes such as the effective utilization of renewable energy such as solar power generation and power supply during disasters. The battery 10 is electrically connected to the life estimation device 20. In this embodiment, the battery condition of the battery 10 is diagnosed by the life estimation device 20, and its lifespan is estimated.

[0021] The life estimation device 20 includes a battery state diagnosis unit 30, an estimation feasibility determination unit 40, a period calculation unit 50, a life estimation unit 60, an estimation accuracy calculation unit 70, an estimation accuracy determination unit 80, and a storage unit 90 related to the storage battery 10. The storage unit 90 stores battery state data 91, period data 92, relational expression data 93, life estimation data 94, and determination data 95, respectively, in an input / output manner. Note that the arrows shown in Figure 1 represent the main data flow, and some are omitted.

[0022] (Battery status diagnosis unit 30) As shown in Figures 1 and 4, the battery state diagnostic unit 30 measures the battery capacity Q as the current battery state value of the battery 10 in operation. The measurement of the battery capacity Q is performed periodically at predetermined intervals. In this embodiment, the periodic measurement is set, for example, once a week at a predetermined time. The battery capacity Q includes the actual measured value itself, or the ratio of the actual measured value to the total capacity (referred to as the capacity retention rate in this embodiment). In Figure 4, etc., the battery capacity Q is shown as the capacity retention rate. In this embodiment, the battery capacity Q is used to measure the battery state value of the battery 10, but other parameters correlated with the battery state value of the battery 10, such as the internal resistance of the battery 10, can also be used. The actual measured value of the battery capacity Q measured periodically by the battery state diagnostic unit 30 x The data is sequentially stored and accumulated in the memory unit 90 as battery status data 91, associated with time information.

[0023] (Estimation possibility determination unit 40) As shown in FIGS. 1, 3, 4, etc., the estimation feasibility determination unit 40 determines whether to estimate the life of the storage battery 10. That is, the estimation feasibility determination unit 40 determines whether there is sufficient measured value Q data for estimating the life of the storage battery 10, and determines whether the number of data of the storage battery capacity Q stored in the storage unit 90 is equal to or greater than the determination value N. x The number of data of the storage battery capacity Q is the number during a predetermined period from the time T0 when the life estimation of the storage battery 10 starts, in this embodiment, from the time when the operation of the storage battery 10 starts to the current time T. a In this embodiment, the determination value N is set to, for example, 5 [points]. It is considered that at least 5 [points] of data of the storage battery capacity Q are required to ensure sufficient accuracy of the life estimation of the storage battery 10. The determination value N is stored in the storage unit 90 as determination data 95. now a a

[0024] (Period calculation unit 50) The period calculation unit 50 calculates the total time t, cycle time t, storage time t, and time ratio A related to the storage battery 10 during operation. The total time t is the total time from the above-mentioned time T0 to the time T. sum The cycle time t is the time related to the charge-discharge cycle in which the charge-discharge operation of the storage battery 10 is performed. cyc The storage time t is the time related to the mere storage elapsed time when the charge-discharge operation of the storage battery 10 is not performed. st The total time t is also the time obtained by adding the cycle time t and the storage time t, and can be expressed as t = t + t. sum now cyc st sum cyc st sum cyc st The time ratio A is the ratio of the cycle time t to the storage time t, and can be expressed as A = t / t. cyc st st cyc

[0025] The period calculation unit 50 determines that the input / output current I of the storage battery 10 during operation is within the determination value ±I​​​​​​​​​​​​​​​​a (See Figure 3) When the change is greater than or equal to the cycle time t of the charge-discharge cycle, cyc The timing is measured as follows. The determination value of this embodiment ±I a For example, it is set to ±1[A]. On the other hand, the input / output current I of the storage battery 10 is set to the determination value ±I a When the change is less than t, it is simply a matter of the preservation time t related to the preservation process. st It is timed as follows: the cycle time t that occurs at each moment. cyc and storage time t st These are accumulated in each case. Incidentally, the total time t sum , cycle time t cyc , and storage time t st Each of these can be timed individually, or any two can be timed and the remaining one calculated. Total time t sum , cycle time t cyc , storage time t st The time ratio A and the time ratio A are stored in the storage unit 90 as period data 92, respectively.

[0026] (Life estimation section 60) The lifetime estimation unit 60 calculates the time from the above-mentioned time T0 to the current time T now Battery capacity Q and cycle time t within the time range up to cyc , and storage time t st Based on the data, an approximate power law formula [Equation 1] is obtained using least squares approximation. That is, the coefficients Q0, k1, k2, α1, and α2 of the approximate formula are calculated. In addition, along with the calculation of the coefficients Q0, k1, k2, α1, and α2, the estimated value of the battery capacity Q is also calculated. a It is also calculated.

[0027]

number

[0028] The above formula [Equation 1] used to estimate the lifespan of the battery 10 in this embodiment is the cycle time t related to the charge-discharge cycle of the battery 10. cyc The section and the preservation time t related to the preservation process. st The formula is structured by dividing it into two terms. This is because the inventors believe that the performance degradation of the battery 10 due to the charge-discharge cycle is different from the performance degradation due to simple storage. Furthermore, the formula is structured as a so-called root law, which utilizes the fact that the square root of the operating time of the battery 10 (including the time itself or the number of cycles) is proportional to the battery capacity. That is, the coefficients α1 and α2 are not only "1 / 2", but also other real numbers, forming a "power law". This is because the inventors believe that this can provide a better approximation than the root law depending on the condition of the battery 10. Thus, the estimated value of the battery capacity Q is calculated. a This information is also sequentially stored in the memory unit 90 as lifetime estimation data 94.

[0029] (Estimated accuracy calculation unit 70) The estimation accuracy calculation unit 70 calculates the estimated value Q of the battery capacity Q. a and measured value Q x Calculate the correlation coefficient r between the two.

[0030] (Estimation accuracy determination unit 80) The estimation accuracy determination unit 80 determines that the correlation coefficient r is equal to the determination value r. a Is the estimated value Q greater than or equal to the desired value? a The measured value Q x Determine if it approximates the given value. The determination value r in this embodiment a For example, it is set to "0.95". The determination value r in this embodiment a This is stored in the memory unit 90 as judgment data 95. The correlation coefficient r is the judgment value r a If it is less than the estimated value Q of the battery capacity Q calculated by the life estimation unit 60, the estimation accuracy determination unit 80 determines the estimated value Q of the battery capacity Q calculated by the life estimation unit 60.a Measured value Q x If the approximation is less than desired, the estimation accuracy is judged to be poor. On the other hand, if the correlation coefficient r is less than the judgment value r a In this case, the estimation accuracy determination unit 80 determines the estimated value Q of the battery capacity Q calculated by the life estimation unit 60. a Measured value Q x The approximation is deemed to be better than desired, and the estimation accuracy is judged to be good.

[0031] If the estimation accuracy is determined to be poor, the lifetime estimation unit 60 will determine the time T0 for which the next data is available from time T0. ’ Change the time range to T0 ’ From time T now Estimated value of battery capacity Q within the time range up to a and measured value Q x The correlation coefficient r is recalculated. In other words, the oldest data is removed. Then, the correlation coefficient r becomes the judgment value r. a The above judgment and calculation operations are repeated with the aim of achieving the above result, that is, determining that the estimation accuracy is good. As this is repeated, older data is gradually removed. Of course, the number of data points for battery capacity Q is determined by the judgment value N. a It will be carried out within the scope described above.

[0032] (Various calculation processes of the life estimation unit 60) Here, the above formula [Equation 1] used in the lifetime estimation unit 60 is given by time ratio A = t st / t cyc , that is, t st =A·t cyc Substituting this into the equation, we get the following equation [Equation 2].

[0033]

number

[0034]

number

[0035] Total time t sum is t sum =t<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The remaining total time t of the storage battery 10 is calculated by the life estimation unit 60 using the above formula [Equation 5]. sum_rem Then, the life estimation device 20 displays the calculation results such as the remaining total time t of the storage battery 10 on a display device (not shown in detail), or outputs the results to related devices, and ends the life estimation process. sum_rem (Processing procedure related to the life estimation of the storage battery 10)

[0039] (Processing procedure related to the life estimation of the storage battery 10) The life estimation process of the storage battery 10 in this embodiment is performed according to the flow shown in FIG. 2. In step S1, the storage battery capacity Q is measured as the current battery state value of the storage battery 10. The measurement of the storage battery capacity Q is performed periodically. The storage battery capacity Q measured each time is used for the life estimation of the storage battery 10 and is stored in the storage unit 90 in association with the time information at the time of measurement.

[0040] In step S2, it is determined whether the number of data of the storage battery capacity Q stored in the storage unit 90 is equal to or greater than the determination value N. It is determined whether there is sufficient data to ensure the life estimation accuracy of the storage battery 10. This process proceeds to step S3 only when the number of data of the storage battery capacity Q is equal to or greater than the determination value N. a In step S2, it is determined whether the number of data of the storage battery capacity Q stored in the storage unit 90 is equal to or greater than the determination value N. It is determined whether there is sufficient data to ensure the life estimation accuracy of the storage battery 10. This process proceeds to step S3 only when the number of data of the storage battery capacity Q is equal to or greater than the determination value N. a In step S2, it is determined whether the number of data of the storage battery capacity Q stored in the storage unit 90 is equal to or greater than the determination value N. It is determined whether there is sufficient data to ensure the life estimation accuracy of the storage battery 10. This process proceeds to step S3 only when the number of data of the storage battery capacity Q is equal to or greater than the determination value N.

[0041] In step S3, the cycle time t related to the charge / discharge cycle of the storage battery 10, the storage time t related to simple storage elapsed time, the total time t related to the operation of the storage battery 10, and the time ratio A are calculated respectively. cyc In step S3, the cycle time t related to the charge / discharge cycle of the storage battery 10, the storage time t related to simple storage elapsed time, the total time t related to the operation of the storage battery 10, and the time ratio A are calculated respectively. st In step S3, the cycle time t related to the charge / discharge cycle of the storage battery 10, the storage time t related to simple storage elapsed time, the total time t related to the operation of the storage battery 10, and the time ratio A are calculated respectively. sum In step S3, the cycle time t related to the charge / discharge cycle of the storage battery 10, the storage time t related to simple storage elapsed time, the total time t related to the operation of the storage battery 10, and the time ratio A are calculated respectively.

[0042] In step S4, the coefficients Q0, k1, k2, α1, α2 of the above formula [Equation 1] related to the current life estimation of the storage battery 10 and the estimated value Q of the storage battery capacity Q are calculated by the least squares approximation using the above formula [Equation 1]. a In step S4, the coefficients Q0, k1, k2, α1, α2 of the above formula [Equation 1] related to the current life estimation of the storage battery 10 and the estimated value Q of the storage battery capacity Q are calculated by the least squares approximation using the above formula [Equation 1].

[0043] In step S5, the correlation coefficient r between the estimated value Q of the storage battery capacity Q and the measured value Q is calculated. a In step S5, the correlation coefficient r between the estimated value Q of the storage battery capacity Q and the measured value Q is calculated. x In step S5, the correlation coefficient r between the estimated value Q of the storage battery capacity Q and the measured value Q is calculated. In step S6, the correlation coefficient r is determined by the judgment value r a Is the estimated value Q greater than or equal to the desired value? a The measured value Q x The determination is made as to whether it approximates the given value. The correlation coefficient r is used to determine the determination value r. a Less than, i.e., the estimated value of the battery capacity Q. a Measured value Q x If the approximation falls below the desired level, the estimation accuracy is judged to be poor. This process proceeds to step S7.

[0044] In step S7, the time T0 of the next data is T0 ’ The time range is changed, and steps S2 to S6 above are repeated. In other words, the estimated battery capacity Q is obtained by removing the oldest data. a and measured value Q x The correlation coefficient r is recalculated, and the correlation coefficient r is the judgment value r a The process described above, which aims to determine that the estimation accuracy is good, is repeated. Note that step S2 is included in this iterative process, and the determination value N a The number of data points for the above battery capacity Q is guaranteed.

[0045] In step S6 above, the correlation coefficient r is the determination value r a In other words, the estimated value of the battery capacity Q is Q. a Measured value Q x If the approximation is better than desired, the estimation accuracy is judged to be good. This process proceeds to step S8.

[0046] In step S8, the estimated cycle life t of the battery 10 is calculated using the above formula [Equation 3]. cyc_end The following is calculated: Battery 10 has a lifespan determination capacity Q end The time required for the charge-discharge cycle to reach that point is calculated.

[0047] In step S9, the estimated lifespan t of the battery 10 is calculated using the above formula [Equation 4]. sum_end The following is calculated: Battery 10 has a lifespan determination capacity Q end The total time required to reach the destination is calculated. In step S10, the estimated lifetime t is calculated using the above formula [Equation 5]. sum_end From operating time t sum_now The remaining total time t of the battery 10 after subtraction sum_rem This is calculated. In other words, the battery 10 has a lifespan determination capacity Q. end Total remaining time t until reached sum_rem This allows us to understand the situation and use that information to consider maintenance, replacement, and other measures for the battery storage system 10.

[0048] (Operation of this embodiment) The operation of this embodiment will now be described. In estimating the lifespan of the battery 10 in this embodiment, a calculation method including the least-squares approximation expressed by the above formula [Equation 1] is used, thereby determining the remaining total time t sum_rem Significant improvement in accuracy can be expected. The formula used in this embodiment [Equation 1] represents the cycle time t related to the charge-discharge cycle of the storage battery 10. cyc The section and the storage time t related to the storage process. st The terms are separated. Since the performance of the battery 10 differs significantly between charge-discharge cycles and simple storage, we believe that performing calculations individually will greatly contribute to improving the accuracy of life estimation. Furthermore, equation [Equation 1] allows for approximations other than the square root rule, which is commonly used in estimating the life of the battery 10. We believe that this also contributes to improving the accuracy of life estimation.

[0049] Using the life estimation method of this embodiment, as shown in Figure 4, the estimated value of the battery capacity Q of the battery 10 is Q a and measured value Q x This provides a sufficient approximation over the entire period from the initial stages of operation to the end of its lifespan. In particular, the battery 10 has a lifespan determination capacity Q. end At the end of life, when the estimated value Q is reached, a and measured value Q x Although they tend to diverge, in this embodiment the error time t between them a It can be kept sufficiently small.

[0050] In contrast, the comparative example's life estimation method, which uses a general square root rule without dividing the operating time of the battery 10, yields the estimated battery capacity Q of the battery 10, as shown in Figure 6. a and measured value Q x Although it approximates the mid-term operational results, this embodiment is still superior. Furthermore, the estimated value Q in the initial operational period a and measured value Q x A slight discrepancy can be observed between these two. In particular, the lifetime determination capacity Q end At the end of life, when it reaches this point, the estimated value Q a and measured value Q x The discrepancy between them is very large, and the error time t between them is x It is very large.

[0051] Thus, compared to the comparative example, it can be said that by using the battery life estimation method of this embodiment, the accuracy of battery life estimation can be sufficiently improved, especially in the end of the battery life, which is a time when accuracy tends to deteriorate.

[0052] (Effects of this embodiment) The effects of this embodiment will now be explained. (1) Cycle time t related to charge-discharge cycles during the operation period of the battery 10 cyc And, the storage time t related to the storage process st The calculation is performed separately for the two components. Next, the measured value of the battery capacity Q used as the battery state value of the battery 10 is Q. x , cycle time t cyc , and storage time t st Based on this, an approximate formula for the power law (the approximate formula shown in [Equation 1] above) is obtained using the least squares approximation. Then, based on the obtained approximate formula, the life determination capacity Q, which is the desired lifespan of the storage battery 10, is determined. end Life information up to (In this embodiment, the estimated cycle life t of the storage battery 10) cyc_end , estimated lifespan t sum_end , and remaining total time t sum_remThe calculation of the battery life is performed. In other words, by focusing on the fact that the performance of the battery 10 differs greatly between charge-discharge cycles and simple storage, and performing calculations individually, it is possible to expect a significant improvement in the accuracy of life estimation. Furthermore, by using a power law as the approximation formula, it is possible to perform approximations other than the square root law, which is commonly used in life estimation of the battery 10, depending on the situation. This also contributes to the expected improvement in life estimation accuracy.

[0053] (2) Measured value Q of the battery capacity Q used as the battery state value of the battery 10 x The judgment value is N a If there is a sufficient number of these items, the process proceeds from step S2 to step S3 and beyond in Figure 2, and the lifespan of the storage battery 10 is estimated. This also contributes to the expectation of further improvement in the accuracy of the lifespan estimation.

[0054] (3) Estimated value Q of the battery capacity Q to be used as the battery state value of the battery 10 a Measured value Q x The correlation coefficient r with the determination value r a When the above approximation is met, the process proceeds from step S6 to step S7 in Figure 2, and the lifespan of the storage battery 10 is estimated. In this embodiment, the lifespan is estimated by sequentially removing older data starting from the initial time T0 of the storage battery 10's operation. This also allows for further improvement in the accuracy of the lifespan estimation.

[0055] (Example of change) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0056] The numerical values ​​and formulas mentioned above are examples only and may be modified as appropriate. The operating time of battery 10 includes either the time itself or the number of cycles. • Total operating time of battery 10 t sum , cycle time t cyc , and storage time t stEach of these can be calculated using individual timings, or any two can be timed and the remaining one calculated.

[0057] • In calculating the lifespan, the battery capacity Q was used as the battery state value of the battery 10, but other parameters that correlate with the battery state value of the battery 10, such as the internal resistance of the battery 10, may also be used.

[0058] • In calculating the lifetime estimate, although not specifically mentioned in the above embodiment, as shown in Figure 5, time T now Measured value Q x , in other words, the latest measured value Q x and estimated value Q a It may also be a condition that these two values ​​match. In this way, the latest measured value Q x and estimated value Q a By aligning these two factors, the accuracy of lifespan estimation can be improved.

[0059] • Estimate lifespan from time T0 to the current time T now The method was to perform the operation based on data acquired up to that point, but as shown in Figure 5, from the initial time T0 of operation of the storage battery 10 to, for example, time T a The lifespan of the battery 10 may be estimated by excluding older data up to time T. a This could be a time set at a certain interval from the start of operation of the battery 10, or the current time T now The time may also fluctuate in conjunction with this. By excluding older data from the early stages of operation, which show a relatively different pattern of change from the end of the battery 10's lifespan, the estimated value Q, especially at the end of its lifespan, can be obtained. a and measured value Q x The time difference t b This leads to keeping the value of the lifetime estimate smaller. In this way, it is possible to improve the accuracy of the lifetime estimate.

[0060] • As lifespan information up to the desired lifespan, the estimated cycle life t of the storage battery 10. cyc_end , estimated lifespan t sum_end , total remaining time t sum_remAll of the calculations and displays may be performed, or at least one calculation and display may be performed. Furthermore, lifespan information may be expressed in ways other than time.

[0061] The battery 10 may have a configuration other than a stationary lithium-ion battery. The battery 10 may also be used in conjunction with renewable energy power generation equipment other than solar power generation.

[0062] (Note) The technical concepts that can be understood from the above embodiments and modified examples are described below. (i) The approximate formula for the power law is: [Estimated battery state value] = [Initial battery state value] - [Power of battery cycle time] - [Power of battery storage time]. Battery life estimation device.

[0063] (b) The approximate formula for the power law is: [Estimated battery state value] = [Initial battery state value] - [Power of battery cycle time] - [Power of battery storage time]. Method for estimating the lifespan of a storage battery. [Explanation of Symbols]

[0064] 10… Storage battery 20…Life estimation device 30...Battery status diagnostic unit 40…Estimation possibility determination unit 50... Period calculation section 60…Life estimation section 70... Estimation accuracy calculation unit 80…Estimation accuracy determination unit 90...Storage section 91...Battery status data 92… Period data 93…Relational formula data 94…Life expectancy estimation data 95... Judgment data Q...Battery capacity (battery status value) Q x ...actual measured value Q a ...estimated value t cyc ...cycle time t st …Storage time t cyc_end ...Estimated cycle life (lifetime information) t sum_end …Estimated lifespan (lifetime information) t sum_rem …Total remaining time (life information) r...correlation coefficient r a ...Judgment value N a ...Judgment value

Claims

1. A battery life estimation device that estimates the life of a storage battery based on an approximate formula obtained from measured values ​​of the battery state of the storage battery, A period calculation unit calculates the cycle time for charge-discharge cycles in which charge-discharge operations were performed during the operating period of the storage battery, and the storage time for storage periods in which no charge-discharge operations were performed. The system comprises: a life estimation unit that obtains an approximate formula for a power law using least-squares approximation based on the measured battery state value of the storage battery, the cycle time, and the storage time, and calculates life information up to the desired life of the storage battery based on the approximate formula; Battery life estimation device.

2. The system includes an estimation feasibility determination unit that determines whether the number of measured battery state values ​​of the storage battery is equal to or greater than a determination value for determining whether the number is sufficient for estimating the lifespan of the storage battery, and that, based on the determination that it is equal to or greater than the determination value, allows the storage battery life estimation process, including the lifespan estimation unit, to proceed. The battery life estimation device according to claim 1.

3. The life estimation unit obtains an estimated value of the battery state value of the storage battery based on the approximation formula, The system includes an estimation accuracy determination unit that determines whether the estimated value of the battery state value of the storage battery is in an approximate state where the correlation coefficient with the measured value of the battery state value of the storage battery is greater than or equal to a determination value, and that permits the battery life estimation process, including the life estimation unit, based on the determination that it is greater than or equal to the determination value. The battery life estimation device according to claim 1.

4. The life estimation unit obtains an estimated value of the battery state value of the storage battery based on the approximation formula, The system is configured to obtain the approximation formula, with the condition that the latest measured value of the battery state of the storage battery matches the corresponding estimated value. The battery life estimation device according to claim 1.

5. The life estimation unit is configured to obtain the approximate formula by excluding the measured values ​​of the battery state values ​​of the storage battery during the initial stages of operation. The battery life estimation device according to claim 1.

6. A method for estimating the lifespan of a storage battery, which estimates the lifespan of the storage battery based on an approximate formula obtained from measured values ​​of the battery state of the storage battery, The cycle time for charge-discharge cycles during the operation period of the aforementioned battery, and the storage time for storage periods during which no charge-discharge operations were performed are calculated. Based on the measured battery state value of the storage battery, the cycle time, and the storage time, an approximate formula for a power law is obtained using least-squares approximation, and life information up to the desired lifespan of the storage battery is calculated based on the approximate formula. Method for estimating the lifespan of a storage battery.

Images