Degradation degree determination device

Abstract

To provide a deterioration degree determination device for improving determination accuracy while shortening a time to determine the deterioration degrees of secondary batteries constituting a battery pack.SOLUTION: A deterioration degree determination device 1 determines the deterioration degrees of secondary batteries 21-28 constituting a battery pack 2. A battery characteristic acquisition section 11 acquires battery characteristics of the secondary batteries 21-28 during charging / discharging. A reference deterioration degree estimation section 14 estimates the deterioration degree of a reference secondary battery 20 based on the use history of the reference secondary battery 20. A feature value generation section 15 generates a feature value for each one of the secondary batteries 21-28 based on the battery characteristics or battery characteristic relation values. A deterioration degree variation estimation section 16 compares the feature value of the reference secondary battery 20(21) with the feature values of the secondary batteries 22-28, so as to estimate variations of the deterioration degrees of the secondary batteries 22-28 from the reference secondary battery 20. A deterioration degree estimation section 17 estimates the deterioration degrees of the secondary batteries 22-28 other than the reference secondary battery 20 in the battery pack 2 based on the deterioration degree of the reference secondary battery 20 and the estimation results of the variations.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a deterioration level determining device. [Background technology]

[0002] Various deterioration level determination devices have been studied for determining the deterioration level of secondary batteries that constitute a battery pack. For example, Patent Document 1 discloses a device configured to detect the deterioration level of a secondary battery from the slope of a line obtained by measuring the complex impedance of the secondary battery at different frequencies. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 115038 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configuration disclosed in Patent Document 1 requires diagnosing the degradation levels of all secondary batteries included in the battery pack, which takes a long time to determine the degradation level. Furthermore, measuring the complex impedance requires expensive equipment, and the complex impedance measurement itself takes a relatively long time. Because the usage history of the secondary batteries is not taken into account, there is room for improvement in the accuracy of determining the degradation level.

[0005] The present invention has been made in consideration of such problems, and aims to provide a deterioration level determination device that can improve the accuracy of determination while shortening the time required to determine the deterioration level of secondary batteries that make up a battery pack. [Means for solving the problem]

[0006] One aspect of the present invention is a deterioration level determination device (1) for determining a deterioration level of secondary batteries (21-28) constituting a battery pack (2), comprising: a charge / discharge control unit (10) that charges and discharges the assembled battery; a battery characteristics acquisition unit (11) that acquires battery characteristics of the secondary battery during charging and discharging; a reference secondary battery setting unit (12) that sets a reference secondary battery (20) from among the secondary batteries that constitute the battery pack; a usage history acquisition unit (13) that acquires the usage history of the reference secondary battery; a reference deterioration level estimation unit (14) that estimates a deterioration level of the reference secondary battery based on a usage history of the reference secondary battery; a feature creation unit (15) that creates a feature of the secondary battery based on the battery characteristics or a battery characteristic related value calculated from the battery characteristics; a deterioration degree variation estimation unit (16) that compares a characteristic amount of the reference secondary battery with a characteristic amount of the secondary batteries other than the reference secondary battery in the battery pack, and estimates a deterioration degree variation of the secondary batteries other than the reference secondary battery from the reference secondary battery; and a deterioration level estimation unit (17) that estimates the deterioration levels of the secondary batteries other than the reference secondary battery in the battery pack based on the deterioration level of the reference secondary battery and the estimated result of the variation. [Effects of the Invention]

[0007] In the deterioration level determination device according to the above aspect, the deterioration level of a reference secondary battery among the secondary batteries constituting the battery pack is estimated based on its usage history, thereby enabling highly accurate estimation of the deterioration level of the reference secondary battery. Meanwhile, for secondary batteries other than the reference secondary battery, the deterioration level variation from the reference secondary battery is estimated without using the usage history, and the deterioration level of the secondary batteries other than the reference secondary battery is estimated based on the deterioration level of the reference secondary battery and the estimated result of the variation. This significantly reduces the computational load required to estimate the deterioration level of the secondary batteries other than the reference secondary battery and shortens the time required to determine the deterioration level. Furthermore, the deterioration level variation of the secondary batteries other than the reference secondary battery from the reference secondary battery is estimated based on feature quantities created based on the battery characteristics or battery characteristic-related values of the secondary batteries during charging and discharging, enabling highly accurate estimation and improving the accuracy of the deterioration level determination. Furthermore, since there is no need for expensive equipment, such as that required for calculating complex impedance, costs can be reduced.

[0008] As described above, according to the present invention, it is possible to provide a deterioration level determining device that can improve the accuracy of determining the deterioration level while shortening the time required to determine the deterioration level of secondary batteries that make up a battery pack.

[0009] In addition, the symbols in parentheses in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a deterioration level determining device according to a first embodiment. [Figure 2] FIG. 1 is a conceptual diagram showing the configuration of a deterioration level determining device according to a first embodiment. [Figure 3] 3 is a flowchart showing a control mode of the deterioration level determining device according to the first embodiment. [Figure 4] FIG. 10 is a conceptual diagram showing the configuration of a deterioration level determining device in a first modified embodiment. [Figure 5]FIG. 10 is a block diagram showing the configuration of a deterioration level determining device according to a second embodiment. [Figure 6] FIG. 10 is a flowchart showing a control mode of the deterioration level determining device in the second embodiment. [Figure 7] FIG. 11 is a flowchart showing a control mode of the deterioration level determining device according to the third embodiment. [Figure 8] FIG. 10 is a flowchart showing a control mode of the deterioration level determining device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) An embodiment of the deterioration level determining device will be described with reference to FIGS. The deterioration level determining device 1 of the first embodiment shown in FIG. The deterioration level determination device 1 includes a charge / discharge control unit 10, a battery characteristic acquisition unit 11, a reference secondary battery setting unit 12, a usage history acquisition unit 13, a reference deterioration level estimation unit 14, a feature creation unit 15, a deterioration level variation estimation unit 16, and a deterioration level estimation unit 17. The charge / discharge control unit 10 then charges and discharges the battery pack 2. The battery characteristics acquisition unit 11 acquires the battery characteristics of the secondary batteries 21 to 28 during charging and discharging. The reference secondary battery setting unit 12 sets a reference secondary battery 20 from among the secondary batteries 21 to 28 that make up the battery pack 2 based on the battery characteristics or battery characteristic-related values calculated from the battery characteristics. The usage history acquisition unit 13 acquires the usage history of the reference secondary battery 20 . The reference deterioration level estimating unit 14 estimates the deterioration level of the reference secondary battery 20 based on the usage history of the reference secondary battery 20 selected from the secondary batteries 21-28. The feature creation unit 15 creates a feature for each of the secondary batteries 21 to 28 based on the battery characteristics or battery characteristic related values calculated from the battery characteristics. The deterioration degree variation estimation unit 16 compares the characteristic amounts of the reference secondary battery 20 with the characteristic amounts of the secondary batteries 22 to 28 other than the reference secondary battery 20 in the battery pack 2, and estimates the variation in the deterioration degrees of the secondary batteries 22 to 28 other than the reference secondary battery 20 from the reference secondary battery 20. The deterioration level estimating unit 17 estimates the deterioration levels of the secondary batteries 22 to 28 other than the reference secondary battery 20 in the battery pack 2 based on the estimated deterioration level and variation of the reference secondary battery 20.

[0012] The deterioration level determining device 1 of this embodiment will be described in detail below. The secondary batteries 21 to 28 that are the targets of the deterioration level determination device 1 of this embodiment constitute a battery pack 2. As shown in Fig. 2, in this embodiment, the battery pack 2 constitutes a power source mounted on a vehicle 100 such as an electric vehicle or a hybrid vehicle. Note that the secondary batteries 21 to 28 may also be single battery cells.

[0013] A charge / discharge control unit 10 shown in FIG. 1 charges and discharges a battery pack 2. The charge / discharge control unit 10 is made up of a computing device capable of executing a predetermined program, and in this embodiment, as shown in FIG. 2, the charge / discharge control unit 10 is mounted on an external terminal 3 provided outside a vehicle 100. The charge / discharge control unit 10 is configured to control charging and discharging of the battery pack 2 via an external connection unit 101 provided on the vehicle 100 and a BMU (battery management unit) mounted on the vehicle 100. Alternatively, the charge / discharge control unit 10 may be configured to directly charge and discharge the battery pack 2. In this specification, charging and discharging include only charging, only discharging, charging followed by discharging, and discharging followed by charging.

[0014] The battery characteristics acquisition unit 11 shown in FIG. 1 acquires the battery characteristics of the secondary batteries 21-28. The battery characteristics may be at least one of the battery voltage, current, temperature, and state of charge (SOC) of the secondary batteries 21-28. The battery characteristics acquisition unit 11 may be configured with a sensor and a computing device capable of detecting the battery characteristics to be acquired. For example, the battery characteristics acquisition unit 11 may be configured to use a voltage sensor, a current sensor, a temperature sensor, etc., or to calculate and acquire the SOC based on these values. Note that the SOC may be calculated based on values obtained by each sensor and then further processed or corrected in a predetermined manner. In this embodiment, as shown in FIG. 2, the battery characteristics acquisition unit 11 is configured with a voltage sensor, a current sensor, and a temperature sensor (not shown) provided in a BMU (battery management unit) mounted on the vehicle 100.

[0015] The data acquired by the battery characteristic acquisition unit 11 can be stored in the battery characteristic storage unit 111 shown in Fig. 1. The battery characteristic storage unit 111 is made of a rewritable nonvolatile memory. In this embodiment, as shown in Fig. 2, the battery characteristic storage unit 111 is provided in the BMU.

[0016] The reference secondary battery setting unit 12 shown in FIG. 1 sets the reference secondary battery 20 from among the secondary batteries 21 to 28. The reference secondary battery setting unit 12 is made up of a processor capable of executing a predetermined program for setting the reference secondary battery 20, and in this embodiment, as shown in FIG. 2, the reference secondary battery setting unit 12 is mounted on an external terminal 3 provided outside the vehicle 100. The method for setting the reference secondary battery 20 in the reference secondary battery setting unit 12 is not limited, but in this embodiment, the reference secondary battery 20 is set based on battery characteristics acquired by the battery characteristics acquisition unit 11 or battery characteristic-related values calculated from the battery characteristics. Note that in this embodiment, for convenience, the secondary battery 21 of the secondary batteries 21 to 28 in FIG. 1 is set as the reference secondary battery 20.

[0017] The battery characteristic relation value is a value derived from the battery characteristics, and may be at least one of, for example, a difference in the battery characteristics over a predetermined period, a resistance value of the secondary battery calculated based on the battery characteristics, a correlation coefficient of the battery characteristics between the secondary batteries arranged adjacent to each other, and a data center of gravity of the battery characteristics of the secondary battery. The battery characteristic relation value can be derived by the reference secondary battery setting unit 12 or the feature creation unit 15 described below.

[0018] The correlation coefficients as the battery characteristic relation values can be calculated as partial correlation coefficients from the components of the inverse covariance matrix of the battery characteristics. The inverse covariance matrix can be calculated by the reference secondary battery setting unit 12 or the feature creation unit 15 described below by performing sparse regularization using multiple types of battery characteristics as variables. The derived battery characteristic relation values can be stored in the battery characteristic storage unit 111 described above.

[0019] The usage history acquisition unit 13 shown in FIG. 1 acquires the usage history of the reference secondary battery 20. In this embodiment, as shown in FIG. 2, the usage history acquisition unit 13 is configured by a BMU mounted on the vehicle 100. The usage history of the secondary battery may be at least one of the following: temperature, state of charge (SOC), frequency of current squared, number of days of use, integrated amount of charge and discharge, and mileage of the vehicle when the battery pack 2 is mounted on the vehicle. The temperature in the usage history may be the battery temperature or the outside air temperature. The frequency of current squared is a value obtained by squaring the current value during charge and discharge, and is an index of the amount of heat generated in the secondary batteries 21-28 due to charge and discharge. The usage history may be acquired over a predetermined period. The predetermined period may be any period up to the present, or may be the entire period up to the present. Note that for a portion of the period, interpolation may be performed based on previously acquired usage history or on estimated values obtained using values acquired by each sensor or values acquired from a model battery, etc., thereby eliminating the need to acquire actual usage history and reducing data acquisition costs. Furthermore, in order to interpolate the usage history, the usage status from the present onward may be estimated based on estimated values obtained by utilizing the already acquired usage history, values acquired by each sensor, values acquired from a degradation estimation model, etc., and this may be included in the usage history. Note that the usage history acquisition unit 13 may similarly acquire the usage history of secondary batteries 22 to 28 other than the reference secondary battery 20, along with the usage history of the reference secondary battery 20.

[0020] The data acquired by the usage history acquisition unit 13 can be stored in the usage history storage unit 131 shown in Fig. 1. The usage history storage unit 131 is made up of a rewritable non-volatile memory. In this embodiment, as shown in Fig. 2, the usage history storage unit 131 is provided in the BMU.

[0021] The reference degradation level estimation unit 14 shown in FIG. 1 estimates the degradation level of the reference secondary battery 20 based on the usage history of the reference secondary battery 20. The reference degradation level estimation unit 14 is configured with a processor capable of executing a predetermined program for estimating the degradation level of the reference secondary battery 20. The method of estimating the degradation level in the reference degradation level estimation unit 14 is not limited. For example, a map showing the correspondence between the usage history of the reference secondary battery 20 and the degradation level or a correspondence between the usage history and the degradation level in a degradation estimation model may be created in advance, and the degradation level of the reference secondary battery 20 may be estimated based on these. For example, the correspondence between the usage history and the degradation level may be expressed as a regression equation. When the correspondence between the usage history and the degradation level is expressed as a regression equation, the degradation level may be calculated as the regression coefficient × the usage history + the intercept. The degradation level may include one or more of the following: capacity Ah, resistance mΩ, power Wh, or power W. The regression equation is not limited to linear regression such as simple regression or multiple regression, but may also be linear regression or nonlinear regression utilizing machine learning. Among these, Lasso regression, which is a type of linear regression that utilizes machine learning, is more preferable because it can suppress overlearning. Note that the reference deterioration level estimation unit 14 may be configured to substantially perform the functions of the reference secondary battery setting unit 12 and the usage history acquisition unit 13 described above.

[0022] The feature creation unit 15 shown in Fig. 1 creates a feature for each of the secondary batteries 21 to 28 based on the battery characteristics or battery characteristic-related values. The feature creation unit 15 is made up of a processor capable of executing a predetermined program for calculating the feature. In this embodiment, as shown in Fig. 2, the feature creation unit 15 is provided in an external terminal 3 outside the vehicle 100. Note that the feature creation unit 15 may also be configured by having a processor mounted on a BMU provided in the vehicle 100 execute the program.

[0023] The feature amounts calculated by the feature amount creation unit 15 are stored in a feature amount storage unit 151 shown in Fig. 1. The feature amount storage unit 151 is made up of a rewritable nonvolatile memory. In this embodiment, as shown in Fig. 2, the feature amount storage unit 151 is provided in the external terminal 3. Note that the BMU provided in the vehicle 100 may also include the feature amount storage unit 151.

[0024] The deterioration level variation estimator 16 shown in FIG. 1 compares the characteristic quantities of the reference secondary battery 20 with those of the secondary batteries 21 to 28 other than the reference secondary battery 20 to estimate the variation in the deterioration levels of the secondary batteries 21 to 28 from the reference secondary battery 20. The deterioration level variation estimator 16 is made up of a processor capable of executing a predetermined program for estimating the variation in the deterioration levels. In this embodiment, as shown in FIG. 2, the deterioration level variation estimator 16 is provided in an external terminal 3 outside the vehicle 100. The variation in the deterioration levels may be estimated by creating a map in advance showing the correspondence between the characteristic quantities and the variation in the deterioration levels, and comparing the characteristic quantities of the reference secondary battery 20 with those of the secondary batteries 21 to 28 other than the reference secondary battery 20 based on this map. Alternatively, the variation in the deterioration levels may be estimated by comparing the characteristic quantities of the reference secondary battery 20 with those of the secondary batteries 21 to 28 other than the reference secondary battery 20 based on the correspondence between the characteristic quantities and the deterioration levels in a secondary battery model. For example, the correspondence between the feature amount and the degradation level can be expressed as a regression equation. When the correspondence between the feature amount and the degradation level is expressed as a regression equation, the variation in the degradation level can be calculated as the regression coefficient × the feature amount + the intercept. The variation in the degradation level can include one or more of the following: a capacity variation ΔAh, a resistance variation ΔmΩ, a power variation ΔWh, or a power variation ΔW. The regression equation is not limited to linear regression such as simple regression or multiple regression, but may also be linear regression or nonlinear regression utilizing machine learning. Among these, Lasso regression, which is one type of linear regression utilizing machine learning, is more preferable because it can suppress overlearning. The degradation level variation estimation unit 16 may be configured to substantially perform the function of the feature amount creation unit 15 described above.

[0025] The deterioration level estimation unit 17 shown in FIG. 1 estimates the deterioration levels of the secondary batteries 22 to 28 other than the reference secondary battery 20 in the battery pack 2 based on the deterioration level of the reference secondary battery 20 estimated by the reference deterioration level estimation unit 14 and the estimation result of the deterioration level variation estimation unit 16 of the variations in the deterioration levels of the secondary batteries 21 to 28 from the reference secondary battery 20. The deterioration level estimation unit 17 is made up of a processor capable of executing a predetermined program for estimating the deterioration level based on the estimation result of the deterioration level and variation of the reference secondary battery 20. In this embodiment, as shown in FIG. 2, the deterioration level estimation unit 17 is mounted on an external terminal 3 provided outside the vehicle 100. In this embodiment, when the deterioration level of the reference secondary battery 20 estimated by the reference deterioration level estimation unit 14 is D and the estimation result by the deterioration level variation estimation unit 16 is ΔD, the deterioration level estimation unit 17 can calculate and estimate the deterioration levels of the secondary batteries 21 to 28 other than the reference secondary battery 20 as D+ΔD.

[0026] Next, the control flow of the deterioration level determining device 1 will be described with reference to FIG. First, in step S1 shown in Fig. 3, the charge / discharge control unit 10 charges and discharges the secondary batteries 21 to 28. The charge / discharge is performed while the battery pack 2 is mounted on the vehicle 100, as shown in Fig. 2. In this embodiment, the subsequent steps S2 to S8 are also performed while the battery pack 2 is mounted on the vehicle 100.

[0027] 3, the battery characteristics acquisition unit 11 acquires the battery characteristics of the secondary batteries 21 to 28. The acquired battery characteristics are stored in the battery characteristics storage unit 111. The battery characteristics are at least one of the battery voltage, current, temperature, and state of charge of the secondary batteries 21 to 28.

[0028] 3, steps S3 to S7 and steps S6 to S7 are performed in parallel. First, in step S3, the reference secondary battery setting unit 12 sets the reference secondary battery 20 from among the secondary batteries 21 to . In this embodiment, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on the battery characteristics of the secondary batteries 21 to .

[0029] 3, the usage history acquisition unit 13 acquires the usage history of the reference secondary battery 20. The usage history is at least one of the temperature of the reference secondary battery 20, the state of charge, the frequency of current squared, the number of days of use, the accumulated amount of charge and discharge, and the mileage of the vehicle 100 equipped with the battery pack 2. The acquired usage history is stored in the usage history storage unit 131.

[0030] 3, in step S6, the feature creation unit 15 creates a feature for each of the secondary batteries 21 to 28 based on the battery characteristics or battery characteristic-related values. The created feature is stored in the feature storage unit 151.

[0031] 3, the characteristic amounts of the reference secondary battery 20 are compared with the characteristic amounts of the secondary batteries 21 to 28 other than the reference secondary battery 20 to estimate the variation in the degree of deterioration of the secondary batteries 21 to 28 from the reference secondary battery 20. The estimated variation in the degree of deterioration is stored in the deterioration degree variation storage unit 161.

[0032] 3, in step S8, the deterioration level estimation unit 17 estimates the deterioration levels of the secondary batteries 22 to 28 other than the reference secondary battery 20 in the battery pack 2 based on the deterioration level of the reference secondary battery 20 estimated by the reference deterioration level estimation unit 14 and the estimation result of the deterioration level variation of the secondary batteries 21 to 28 from the reference secondary battery 20 by the deterioration level variation estimation unit 16, and then the flow ends. As a result, the deterioration levels of all the secondary batteries 21 to 28 in the battery pack 2 are estimated with the battery pack 2 mounted on the vehicle 100.

[0033] Next, the effects of the deterioration level determining device 1 of the first embodiment will be described in detail. In the deterioration level determination device 1 of the first embodiment, the deterioration level of the reference secondary battery 20, among the secondary batteries 21 to 28 constituting the battery pack 2, is estimated based on the usage history, allowing for highly accurate estimation of the deterioration level of the reference secondary battery 20. Meanwhile, for the secondary batteries 22 to 28 other than the reference secondary battery 20, the deterioration level is estimated based on the variation in deterioration level from the reference secondary battery 20 without using the usage history, and the deterioration level is then estimated based on the deterioration level of the reference secondary battery 20 and the estimated variation. This significantly reduces the computational load for estimating the deterioration levels of the secondary batteries 22 to 28 other than the reference secondary battery 20, and shortens the overall time required for the device to determine the deterioration levels of the secondary batteries 21 to 28. Furthermore, the variation in deterioration level from the reference secondary battery 20 for the secondary batteries 22 to 28 other than the reference secondary battery 20 is estimated based on feature quantities created based on the battery characteristics or battery characteristic-related values of the secondary batteries 21 to 28 during charging and discharging, allowing for highly accurate estimation, thereby improving the accuracy of determining the deterioration level. Furthermore, since there is no need to use expensive equipment as in the case of calculating complex impedance, costs can be reduced.

[0034] In this embodiment, the battery characteristics are at least one of the battery voltage, current, temperature, and state of charge of the secondary batteries 21 to 28. This makes it possible to adopt elements that reflect the state of the secondary batteries 21 to 28 as the battery characteristics, thereby improving the accuracy of determining the degree of deterioration.

[0035] In this embodiment, the usage history is at least one of the temperature of the reference secondary battery 20, the state of charge, the frequency of current squared, the number of days of use, the accumulated amount of charge and discharge, and the mileage of the vehicle 100 when the battery pack 2 is mounted on the vehicle 100. This allows factors that are likely to affect the deterioration of the secondary battery to be used as the usage history, thereby improving the accuracy of estimating the deterioration level of the reference secondary battery 20.

[0036] In this embodiment, the reference secondary battery 20 is set based on battery characteristics or battery characteristic-related values. This allows the reference secondary battery 20 to be set based on battery characteristics or battery characteristic-related values that fully reflect the states of the secondary batteries 21 to 28, thereby improving the accuracy of estimating the degradation level of the reference secondary battery 20.

[0037] Furthermore, in this embodiment, the battery characteristic relation value is at least one of the difference in battery characteristics over a predetermined period, the resistance value of the secondary batteries 21 to 28 calculated based on the battery characteristics, the correlation coefficient of the battery characteristics between the secondary batteries 21 to 28 arranged adjacent to each other, and the data center of gravity of the battery characteristics of the secondary batteries 21 to 28. This allows the state of the secondary batteries 21 to 28 to be fully reflected in the battery characteristic relation value, thereby improving the accuracy of determining the degree of deterioration.

[0038] In this embodiment, the correlation coefficient is calculated as a partial correlation coefficient from the inverse covariance matrix of the battery characteristics, which allows the feature amount to better reflect the state of the secondary batteries 21 to 28, thereby further improving the accuracy of determining the degree of deterioration of the secondary batteries 21 to 28.

[0039] In this embodiment, the charge / discharge control unit 10 is configured to perform the above-described charging / discharging while the battery pack 2 is mounted on the vehicle 100. This eliminates the need to remove the battery pack 2 from the vehicle 100, thereby improving the efficiency of determining the deterioration level.

[0040] In this embodiment, the charge / discharge control unit 10 is configured to perform the above-mentioned charging / discharging via devices mounted on the vehicle 100. This allows the configuration of the deterioration level determination device 1 to be simplified and made smaller.

[0041] The deterioration level determination device 1 of the first embodiment also includes a reference secondary battery setting unit 12 for setting the reference secondary battery 20. The reference secondary battery setting unit 12 can set the reference secondary battery 20 from among the secondary batteries 21 to 28 based on a correlation coefficient calculated as a battery characteristic relation value calculated from the battery characteristics using a partial correlation coefficient from components of an inverse covariance matrix of the battery characteristics. This makes it possible to determine the deterioration level of both the least deteriorated and most deteriorated secondary batteries 21 to 28 in the battery pack 2 with high accuracy.

[0042] In the first embodiment, the external terminal 3 is directly connected to the external connection unit 101 of the vehicle. Alternatively, as shown in FIG. 4 , a communication unit 105 is provided in the vehicle 100, and a communication unit 31 is also provided in the external terminal 3, so that the external terminal 3 and the vehicle 100 can be connected via wireless communication. The communication units 105 and 31 may also be used to connect to the external terminal 3 located outside the vehicle 100 via a network using a cloud system. According to the first embodiment, even if the external terminal 3 and the vehicle 100 are remote from each other, it is possible to determine the deterioration level of the secondary batteries 21 to 28 installed in the vehicle 100. This also facilitates determining the deterioration level in real time, updating programs, and executing programs using AI technology.

[0043] As described above, according to the first embodiment and the first modified embodiment, it is possible to provide a deterioration level determining device 1 that can improve the accuracy of determination while shortening the time required to determine the deterioration level of the secondary batteries 21 to 28 that make up the battery pack 2.

[0044] (Embodiment 2) 5, the deterioration level determination device 1 of the second embodiment has a temperature acquisition unit 110 and an acquired temperature storage unit 112. In the deterioration level determination device 1 of the first embodiment described above, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on the battery characteristics or battery characteristic-related values acquired by the battery characteristics acquisition unit 11. However, in the deterioration level determination device 1 of the second embodiment, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on temperature data acquired by the temperature acquisition unit 110.

[0045] The temperature acquisition unit 110 shown in FIG. 5 can be composed of a plurality of temperature sensors. In the second embodiment, the temperature acquisition unit 110 is configured to detect the temperatures of two secondary batteries 21 and 27 out of the secondary batteries 21 to 28 constituting the battery pack 2, and the external devices 102 and 103. The secondary battery 21 is expected to have the lowest temperature among the secondary batteries 21 to 28 constituting the battery pack 2, and the secondary battery 27 is expected to have the highest temperature among the secondary batteries 21 to 28. In the present embodiment, the external device 102 is a cooling fan (not shown) mounted on the vehicle 100, and the external device 103 is a battery heater. The temperature acquisition unit 110 is configured to acquire the temperature of the intake part of the cooling fan 102 and the temperature of the heating part of the battery heater.

[0046] The temperatures of the secondary batteries 21-28 can be predicted taking into consideration the arrangement of the secondary batteries 21-28 in the battery pack 2, the influence of other devices in equipment such as the vehicle 100 in which the battery pack 2 is installed, etc. In the second embodiment, of the secondary batteries 21-28, the secondary battery 21, which is located relatively close to the cooling fan 102 and relatively far from the battery heater 103, is predicted to have the lowest temperature. Furthermore, the secondary battery 27, which is located in the central region of the battery pack 2 and relatively far from the cooling fan 102, is predicted to have the highest temperature.

[0047] The acquired temperature storage unit 112 shown in Fig. 5 is made up of a rewritable nonvolatile memory, and is provided in the BMU of the vehicle 100. Note that in the second embodiment, other configurations are the same as those in the first embodiment shown in Fig. 1, and the same configurations as those in the first embodiment are assigned the same reference numerals and description thereof will be omitted.

[0048] In the control flow of the deterioration level determination device 1 of the second embodiment shown in Fig. 6, step S1 shown in Fig. 6 is performed in the same manner as in the first embodiment shown in Fig. 3. Then, steps S2 and S20 are performed in parallel. In step S20, the temperature acquisition unit 110 acquires the temperatures of the two secondary batteries 21, 27, the temperature of the intake part of the cooling fan 102, and the temperature of the heating part of the battery heater 103. The acquired temperature data is then stored in the acquired temperature storage unit 112.

[0049] Then, in step S3, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on the temperature data acquired by the temperature acquisition unit 110. Then, steps S4 to S8 are performed in the same manner as in the first embodiment shown in Fig. 3, and the flow ends.

[0050] The second embodiment also achieves the same effects as the first embodiment. In the second embodiment, the reference secondary battery 20 is set using the temperatures of the external devices 102 and 103 in addition to the temperatures of the secondary batteries 21 and 27, so that the reference secondary battery 20 can be set to be suitable for estimating the degradation level with higher accuracy. This further improves the accuracy of determining the degradation levels of the secondary batteries 21 to 28.

[0051] (Embodiment 3) The deterioration level determination device 1 of the third embodiment has the same configuration as that of the first embodiment shown in Fig. 1. The deterioration level determination device 1 of the third embodiment determines the deterioration levels of the secondary batteries 21 to 28 according to the control flow shown in Fig. 7. In the control flow shown in Fig. 7, first, as in the first embodiment, in step S1, the charge / discharge control unit 10 charges / discharges the secondary batteries 21 to 28. Thereafter, step S21 and step S2 are performed in parallel.

[0052] 7, the usage history acquisition unit 13 acquires the usage history of the secondary batteries 21 to 28. The acquired usage history is then stored in the usage history storage unit 131. After that, in step S3, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on the usage history of the secondary batteries 21 to 28, and the process proceeds to step S4. Steps S4 and after, as well as steps S2 and S6 to S8, are performed in the same manner as in the first embodiment.

[0053] The third embodiment also achieves the same effects as the first embodiment. In the third embodiment, the usage history of the secondary batteries 21 to 28 is kept when the reference secondary battery 20 is set, so that the most appropriate secondary battery can be selected and set as the reference secondary battery 20 from among the secondary batteries 21 to 28 depending on the usage situation. This further improves the accuracy of determining the degree of deterioration.

[0054] (Embodiment 4) The deterioration level determination device 1 of the fourth embodiment has the same configuration as that of the first embodiment shown in Fig. 1. The deterioration level determination device 1 of the fourth embodiment determines the deterioration levels of the secondary batteries 21 to 28 according to the control flow shown in Fig. 8. In the control flow shown in Fig. 8, first, as in the first embodiment, in step S1, the charge / discharge control unit 10 charges / discharges the secondary batteries 21 to 28. Thereafter, step S23 and step S2 are performed in parallel.

[0055] 8, the usage history acquisition unit 13 determines whether or not there is a previously stored usage history in the usage history storage unit 131. If it is determined in step S23 that there is no previously stored usage history, that is, if an initial deterioration level determination is to be performed, the process proceeds to No in step S23, and in step S24, the usage history acquisition unit 13 acquires the usage history of the secondary batteries 21 to 28. The acquired usage history is stored in the usage history storage unit 131.

[0056] 8, the reference secondary battery setting unit 12 sets the reference secondary battery 20 based on the usage histories of the secondary batteries 21 to 28, and the process proceeds to step S31. In step S31, the usage history of the secondary battery set as the reference secondary battery 20 is saved in the usage history storage unit 131, and the usage histories of the other secondary batteries are discarded from the usage history storage unit 131, and the process proceeds to step S5. Steps S5 and thereafter, as well as steps S2 and S6 to S8, are performed in the same manner as in the first embodiment. However, after step S8, the process proceeds to step S81, where the deterioration level estimation unit 17 determines whether or not to end the deterioration level determination. The criterion for determining whether or not to end the deterioration level determination can be set as appropriate, and for example, the criterion can be whether or not a preset deterioration level determination end timing has arrived. If it is determined in step S81 that the deterioration level determination end timing has arrived, the process proceeds to Yes in step S81, where the deterioration level determination is ended and the control flow ends.

[0057] 8, if it is determined that the timing for ending the deterioration level determination has not yet arrived, the process proceeds to No in step S81 and executes step S1 again. Then, since the previous usage history of the reference secondary battery 20 is stored in the usage history storage unit 131, the reference secondary battery setting unit 12 proceeds to Yes in step S23 and does not update the reference secondary battery 20, but instead estimates the deterioration level of the same reference secondary battery 20 as the previous time in step S5, and then performs the same subsequent steps as the previous time.

[0058] The fourth embodiment also achieves the same effects as the first embodiment. In the fourth embodiment, the usage history of the reference secondary battery 20 set during the previous degradation level determination is stored in the usage history storage unit 131, and the usage histories of the other secondary batteries are discarded, thereby reducing the memory allocation capacity of the usage history storage unit 131. Furthermore, setting of the reference secondary battery 20 by the reference secondary battery setting unit 12 is omitted from the second time onwards, which further reduces the calculation load and further shortens the time required for degradation level determination.

[0059] The present invention is not limited to the above-described embodiments and modifications, and can be applied to various embodiments without departing from the spirit of the present invention. [Explanation of symbols]

[0060] 1 Deterioration degree determination device 2 battery packs 20 standard secondary battery 21~28 Secondary battery 10 Charge / discharge control unit 11 Battery characteristics acquisition unit 14 Standard deterioration degree estimator 15 Feature creation unit 16 Deterioration degree variation estimation section 17 Deterioration degree estimation section 100 vehicles

Claims

1. A deterioration level determination device (1) for determining the deterioration level of secondary batteries (21-28) constituting a battery pack (2), comprising: a charge / discharge control unit (10) for charging / discharging the battery pack; a battery characteristics acquisition unit (11) that acquires battery characteristics of the secondary battery during charging and discharging; a reference secondary battery setting unit (12) that sets a reference secondary battery (20) from among the secondary batteries that constitute the battery pack; a usage history acquisition unit (13) for acquiring a usage history of the reference secondary battery; a reference deterioration level estimation unit (14) that estimates a deterioration level of the reference secondary battery based on a usage history of the reference secondary battery; a feature creation unit (15) that creates a feature of the secondary battery based on the battery characteristics or a battery characteristic related value calculated from the battery characteristics; a deterioration degree variation estimation unit (16) that compares a characteristic amount of the reference secondary battery with a characteristic amount of the secondary batteries other than the reference secondary battery in the battery pack, and estimates a variation in deterioration degree of the secondary batteries other than the reference secondary battery from the reference secondary battery; and a deterioration level estimation unit (17) that estimates the deterioration levels of the secondary batteries other than the reference secondary battery in the battery pack based on the deterioration level of the reference secondary battery and the estimated result of the variation.

2. 2. The deterioration level determining device according to claim 1, wherein the battery characteristics are at least one of the battery voltage, current, temperature, and state of charge of the secondary battery.

3. 2. The deterioration degree determination device according to claim 1, wherein the usage history is at least one of the temperature of the reference secondary battery, the state of charge, the square of the charge / discharge current, the number of days of use, the integrated amount of charge / discharge current, the integrated amount of charge / discharge power, and the mileage of the vehicle when the battery pack is mounted on the vehicle.

4. 4. The deterioration level determining device according to claim 1, wherein the reference secondary battery is set based on the battery characteristics or the battery characteristic-related value.

5. 5. The deterioration level determination device according to claim 4, wherein the battery characteristic relation value is at least one of a difference in the battery characteristics over a predetermined period, a resistance value of the secondary battery calculated based on the battery characteristics, a correlation coefficient of the battery characteristics between the secondary batteries arranged adjacent to each other, and a data center of gravity of the battery characteristics of the secondary battery.

6. 6. The deterioration level determining device according to claim 5, wherein the correlation coefficient is calculated as a partial correlation coefficient from an inverse covariance matrix of the battery characteristics.

7. 7. The deterioration level determining device according to claim 1, wherein the charge / discharge control unit is configured to charge / discharge the assembled battery while the assembled battery is mounted on a vehicle.

8. 8. The deterioration level determining device according to claim 7, wherein the charge / discharge control unit is configured to perform the charge / discharge via a device mounted on the vehicle.

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