Management Device and Management Method for Storage Device

Abstract

To update a temperature correction coefficient according to the deterioration of a power storage device.SOLUTION: A management device 1 which is a BMU 31 of a power storage device 1 executes a third process (S303) of measuring the temperature during discharge, a fourth process (S304) of estimating an internal resistance value of the power storage device 1, a fifth process (S307) of obtaining a temperature correction coefficient corresponding to the measured temperature on the basis of the internal resistance value estimated in the fourth process and the internal resistance value at the reference temperature, and a sixth process (S309) of updating the temperature correction coefficient stored in a storage unit 37B in association with the measured temperature with the temperature correction coefficient obtained in the fifth process.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a management device and a management method for a power storage device.

Background Art

[0002] The internal resistance value [mΩ] of a power storage device such as a lithium-ion secondary battery can be divided into three components: a pure resistance component, a reaction component, and a diffusion resistance. In the estimation of the internal resistance value of a power storage device, it is common to estimate the pure resistance component. In the following description, the internal resistance value refers to the pure resistance component. As shown in the following formula (1), the internal resistance value (pure resistance component) is estimated by dividing the voltage drop amount during discharge (the absolute value of the difference between the voltage V1 before discharge and the minimum voltage V2 during discharge) by the current increase amount during discharge (the absolute value of the difference between the current I1 before discharge and the maximum current I2 during discharge).

Equation

[0003] It is known that the internal resistance value of a power storage device has temperature dependence. For this reason, conventionally, the internal resistance value has also been estimated in consideration of the temperature of the power storage device (see, for example, Patent Document 1). Specifically, the battery control system described in Patent Document 1 holds a plurality of internal resistance values for each temperature range of the battery, and performs calculations such as averaging and the least squares method for each temperature range of the battery to obtain a representative value of the internal resistance value. The battery control system takes an average between the representative resistance values of each temperature range to obtain a representative value of one internal resistance value.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, as a method for estimating the internal resistance value in consideration of the temperature of the power storage device, a method of estimating using a temperature correction coefficient is also known. However, conventionally, the problems in the case of estimating the internal resistance value using the temperature correction coefficient have not been sufficiently studied. This specification discloses a technique capable of updating a temperature correction coefficient according to the deterioration of a power storage device.

Means for Solving the Problems

[0006] According to one aspect of the present invention, a management device for a power storage device includes a voltage sensor that measures the voltage of the power storage device, a current sensor that measures the current of the power storage device, a temperature sensor that measures the temperature of the power storage device, and a storage unit in which a temperature correction coefficient for correcting the internal resistance value of the power storage device to the internal resistance value at a reference temperature is stored in association with the temperature, and a management unit. The management unit performs a first process of measuring a voltage drop amount during discharge of the power storage device by the voltage sensor, a second process of measuring a current increase amount during discharge of the power storage device by the current sensor, a third process of measuring a temperature during discharge of the power storage device by the temperature sensor, a fourth process of estimating the internal resistance value of the power storage device based on the voltage drop amount measured in the first process and the current increase amount measured in the second process, a fifth process of obtaining a temperature correction coefficient corresponding to the temperature measured in the third process based on the internal resistance value estimated in the fourth process and the internal resistance value at the reference temperature, and a sixth process of updating the temperature correction coefficient stored in the storage unit in association with the temperature measured in the third process with the temperature correction coefficient obtained in the fifth process.

Advantages of the Invention

[0007] According to the above configuration, the temperature correction coefficient can be updated according to the deterioration of the power storage device.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0009] (Outline of this embodiment) (1) According to one aspect of the present invention, a management device for a power storage device includes a voltage sensor that measures the voltage of the power storage device, a current sensor that measures the current of the power storage device, a temperature sensor that measures the temperature of the power storage device, and a storage unit in which a temperature correction coefficient for correcting the internal resistance value of the power storage device to the internal resistance value at a reference temperature is stored in association with temperature, and a management unit. The management unit performs a first process of measuring a voltage drop amount during discharge of the power storage device by the voltage sensor, a second process of measuring a current increase amount during discharge of the power storage device by the current sensor, a third process of measuring the temperature during discharge of the power storage device by the temperature sensor, a fourth process of estimating the internal resistance value of the power storage device based on the voltage drop amount measured in the first process and the current increase amount measured in the second process, a fifth process of obtaining a temperature correction coefficient corresponding to the temperature measured in the third process based on the internal resistance value estimated in the fourth process and the internal resistance value at the reference temperature, and a sixth process of updating the temperature correction coefficient stored in the storage unit in association with the temperature measured in the third process with the temperature correction coefficient obtained in the fifth process.

[0010] The internal resistance value of a power storage device is used for predicting charge / discharge power and the like. For example, in the case of a power storage device used for starting a vehicle engine, the internal resistance value of the power storage device is used for predicting whether the power required for engine starting can be supplied (in other words, whether engine starting is possible). In order to use the power storage device safely and efficiently, there is a high need for users to predict charge / discharge power.

[0011] As shown in FIG. 11, generally, the internal resistance value of a power storage device has temperature dependence. Since the power storage device is used at various environmental temperatures, conventionally, the corrected internal resistance value, which is the internal resistance value at the reference temperature, has been obtained by correcting the internal resistance value using a temperature correction coefficient.

[0012] FIG. 12 shows an example of the temperature correction coefficient. Here, 25°C is taken as an example of the reference temperature for explanation. The temperature correction coefficient shown in FIG. 12 is obtained by dividing the internal resistance value at 25°C shown in FIG. 11 by the internal resistance values at respective temperatures. When the reference temperature is 25°C, the temperature correction coefficient at 25°C is 1. The temperature correction coefficient when the temperature is less than 25°C is less than 1, and the temperature correction coefficient when the temperature is higher than 25°C is greater than 1.

[0013] Generally, the internal resistance value of the power storage device increases with use. Even when the power storage device is not in use, the internal resistance value may increase over time. The increase in the internal resistance value is also referred to as the deterioration of the power storage device. Since the temperature characteristics of the internal resistance value change according to the deterioration of the power storage cell, it is desirable to update the temperature correction coefficient according to the deterioration. In FIG. 13, the solid line shows the relationship between the temperature and the internal resistance value before the power storage device deteriorates, and the dotted line shows the relationship between the temperature and the internal resistance value after the power storage device deteriorates. As shown in FIG. 13, the temperature dependence of the internal resistance value changes due to the deterioration of the power storage device. Therefore, if the conventional temperature correction coefficient is used as it is even after the power storage device deteriorates, the correction accuracy of the corrected internal resistance value will decrease. Since the temperature dependence also changes depending on the way the power storage device deteriorates, it is difficult to store the temperature correction coefficient after the power storage device deteriorates in advance as a fixed value in the power storage device. Although it is expected that the temperature dependence will change depending on the design of the power storage device, only power storage devices that have been accelerated in deterioration due to reasons such as the development period can be prepared at the design stage, and there is also the fact that it is difficult to confirm the influence of differences in the way of deterioration at the design stage.

[0014] According to the above management device, since the temperature correction coefficient is obtained based on the internal resistance value estimated in the fourth process and the internal resistance value at the reference temperature, the temperature correction coefficient can be updated according to the deterioration of the power storage device. By updating the temperature correction coefficient according to the deterioration of the power storage device, it is possible to suppress a decrease in the prediction accuracy of charge and discharge power such as whether the engine can be started even when the power storage device deteriorates.

[0015] (2) The memory unit stores the initial internal resistance value at the reference temperature and the internal resistance increase rate. In the fifth process, the management unit may obtain the internal resistance value at the reference temperature based on the initial internal resistance value and the internal resistance increase rate stored in the memory unit.

[0016] According to the above management device, since the internal resistance value at the reference temperature is obtained based on the initial internal resistance value and the internal resistance increase rate, the deterioration of the power storage device is reflected in the internal resistance value at the reference temperature. Therefore, the temperature correction coefficient can be obtained more appropriately according to the deterioration of the power storage device.

[0017] (3) The management unit executes a seventh process of predicting the voltage drop amount during discharge of the power storage device based on the temperature correction coefficient stored in the memory unit associated with the temperature measured in the third process. In the sixth process, when the difference between the voltage drop amount predicted in the seventh process and the voltage drop amount measured in the first process is equal to or greater than a reference value, the temperature correction coefficient stored in the memory unit may be updated.

[0018] When the difference between the voltage drop amount predicted based on the temperature correction coefficient stored in the memory unit and the actually measured voltage drop amount is less than the reference value, it can be said that the temperature correction coefficient stored in the memory unit is generally appropriate. When the temperature correction coefficient stored in the memory unit is generally appropriate, it is not always necessary to update the temperature correction coefficient. According to the above management device, when the difference between the voltage drop amount predicted based on the temperature correction coefficient stored in the memory unit and the actually measured voltage drop amount is less than the reference value, the temperature correction coefficient is not updated, so it is possible to suppress the useless update of the temperature correction coefficient.

[0019] (4) In the sixth process, when the number of times the difference between the temperature correction coefficient obtained in the fifth process and the temperature correction coefficient stored in the memory unit is equal to or greater than a predetermined value within a predetermined period in which the power storage device can be regarded as not being deteriorated is equal to or greater than a predetermined number of times, the temperature correction coefficient stored in the memory unit may be updated.

[0020] Even if the difference between the temperature correction coefficient obtained in the fifth process and the temperature correction coefficient stored in the storage unit is large, if the number of times they are compared is only once, there is a possibility that the difference has become large due to the influence of some error. On the other hand, if the number of times the difference is equal to or greater than a predetermined value is equal to or greater than a predetermined number of times, it can be said that the possibility that the difference has become large due to the influence of the error is small. According to the above-described management device, since the temperature correction coefficient is updated when the number of times the difference between the temperature correction coefficient obtained in the fifth process and the temperature correction coefficient stored in the storage unit is equal to or greater than a predetermined value is equal to or greater than a predetermined number of times, it is possible to suppress the temperature correction coefficient from being erroneously updated due to the influence of some error.

[0021] (5) The management unit may execute an eighth process of obtaining a corrected internal resistance value by correcting the internal resistance value estimated by the fourth process based on a temperature correction coefficient associated with the temperature measured in the third process, a ninth process of estimating an average internal resistance value by weighted-averaging a plurality of corrected internal resistance values obtained in the eighth process according to the difference between the temperature at which each corrected internal resistance value was obtained and a reference temperature, a tenth process of estimating an internal resistance increase rate of the power storage device based on the average internal resistance value estimated in the ninth process, and an eleventh process of updating the internal resistance increase rate stored in the storage unit with the internal resistance increase rate estimated in the tenth process.

[0022] When estimating the internal resistance increase rate based on the average internal resistance value obtained by averaging a plurality of corrected internal resistance values, the estimation accuracy of the internal resistance increase rate is improved as compared with the case of estimating the internal resistance increase rate based on only one corrected internal resistance value. However, the inventor of the present application has found that there are the following problems when estimating the average internal resistance value using the temperature correction coefficient. The graph shown in Fig. 14 approximates the relationship between the temperature and the internal resistance value shown in Fig. 11 as a curve. As can be seen from Fig. 14, when the temperature is low, the variation in the internal resistance value per 1°C is larger than when the temperature is high. When the variation in the internal resistance value is large, the variation in the temperature correction coefficient also becomes large. For this reason, when the internal resistance value is estimated at a low temperature, if a temperature correction coefficient of another temperature is used due to the measurement error of the temperature sensor, the correction accuracy of the corrected internal resistance value decreases because the variation in the temperature correction coefficient is large. Therefore, when the temperature is low, the error in temperature correction greatly affects the estimation accuracy of the average internal resistance value.

[0023] According to the above management device, since the average internal resistance value is estimated by weighted-averaging a plurality of corrected internal resistance values according to the difference between the temperature at which each corrected internal resistance value was obtained and the reference temperature, it becomes difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value. Therefore, according to the above management device, it is possible to suppress a decrease in the estimation accuracy when estimating the average internal resistance value using the temperature correction coefficient. The power storage device may experience a wide range of temperatures such as -30 to 40°C due to seasonal changes over one year. Since the deterioration of the power storage device hardly progresses in a low-temperature environment, it is considered that the deterioration progresses in summer and hardly deteriorates in winter. When the average internal resistance value is estimated by weighted-averaging according to the difference between the temperature at which each corrected internal resistance value was obtained and the reference temperature, the internal resistance value estimated in summer can be actively used to estimate the average internal resistance value, so the estimation accuracy of the internal resistance increase rate is improved. Regarding the update of the temperature correction coefficient, by also using the internal resistance value estimated from autumn to winter, it is possible to correct the temperature correction coefficient when the temperature is low.

[0024] (6) In the ninth process, the management unit may estimate the average internal resistance value using only the corrected internal resistance value whose obtained temperature is equal to or higher than a predetermined lower limit temperature.

[0025] The corrected internal resistance value obtained when the temperature is low may have low correction accuracy. According to the above management device, since the corrected internal resistance value obtained when the temperature is lower than a predetermined lower limit temperature is not used for estimating the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0026] (7) In the ninth process, the management unit may estimate the average internal resistance value using only the corrected internal resistance values obtained at temperatures that account for a predetermined upper percentage of the temperatures at which the corrected internal resistance values were obtained.

[0027] According to the above management device, since it is difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0028] (8) In the ninth process, the management unit may assign higher scores to the corrected internal resistance values obtained at temperatures with a smaller difference from the reference temperature, and perform a weighted average of the corrected internal resistance values based on the scores.

[0029] According to the above management device, since it is difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0030] (9) In the ninth process, the management unit may assign higher scores to the corrected internal resistance values obtained at temperatures with a smaller difference from the reference temperature, and perform a weighted average of only the corrected internal resistance values whose scores are equal to or higher than the reference value.

[0031] According to the above management device, since it is difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0032] (10) In the ninth process, the management unit may assign a higher score to the corrected internal resistance value in the temperature range where the number of times the corrected internal resistance value is obtained is large, and weight-average the corrected internal resistance values according to the scores.

[0033] The corrected internal resistance value in the temperature range where the number of times the corrected internal resistance value is obtained is large has less influence of the measurement error of the temperature sensor due to averaging because the number of corrected internal resistance values obtained is large. Therefore, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the measurement error of the temperature sensor.

[0034] (11) In the eleventh process, when the rate of change of the internal resistance increase rate estimated in the tenth process with respect to the internal resistance increase rate stored in the storage unit is equal to or less than a predetermined value, or when the difference between the internal resistance increase rate stored in the storage unit and the internal resistance increase rate estimated in the tenth process is equal to or less than a predetermined value, the management unit may update the internal resistance increase rate stored in the storage unit with the internal resistance increase rate estimated in the tenth process.

[0035] If the estimation accuracy of the internal resistance increase rate estimated in the tenth process is low, the rate of change of the internal resistance increase rate estimated in the tenth process with respect to the internal resistance increase rate stored in the storage unit may increase. Conversely, when the rate of change of the internal resistance increase rate estimated in the tenth process with respect to the internal resistance increase rate stored in the storage unit is high, the estimation accuracy of the internal resistance increase rate estimated in the tenth process may be low. In that case, it is not desirable to update the internal resistance increase rate stored in the storage unit. The same applies when the difference between the internal resistance increase rate stored in the storage unit and the internal resistance increase rate estimated in the tenth process is large.

[0036] According to the above management device, when the above-described rate of change is equal to or less than a predetermined value, or when the above-described difference is equal to or less than a predetermined value, the internal resistance increase rate stored in the storage unit is updated, so that it is possible to suppress the internal resistance increase rate stored in the storage unit from being updated by an internal resistance increase rate with low estimation accuracy.

[0037] The invention disclosed by this specification can be realized in various forms such as an apparatus, a method, a computer program for realizing the functions of these apparatuses or methods, a recording medium on which the computer program is recorded, and the like.

[0038] <Embodiment 1> Embodiment 1 will be described with reference to FIGS. 1 to 7. In the following description, the reference numerals of the drawings may be omitted for some of the same components.

[0039] (1) Power storage device Referring to FIG. 1, the power storage device 1 according to Embodiment 1 will be described. The power storage device 1 is mounted on a vehicle such as an automobile, and supplies power to an engine starting device 10 (starter motor) and auxiliary devices 12 (power steering, brakes, headlights, air conditioner, car navigation, etc.) provided in the vehicle. The power storage device 1 is charged by a vehicle generator 13 (alternator). The power storage device 1 may be charged by regenerative charging during braking.

[0040] (2) Configuration of the power storage device As shown in FIG. 2, the power storage device 1 includes a housing 71. The housing 71 includes a main body 73 made of a synthetic resin material and a lid 74. The main body 73 is a bottomed cylindrical shape. The main body 73 includes a bottom surface portion 75 and four side surface portions 76. An upper opening 77 is formed at the upper end portion by the four side surface portions 76.

[0041] The housing 71 houses a battery pack 30 composed of a plurality of power storage cells 30A and a circuit board unit 72. The power storage cell 30A is a secondary battery that can be repeatedly charged and discharged, and specifically, for example, a lithium ion secondary battery. The circuit board unit 72 is disposed above the battery pack 30. The lid 74 closes the upper opening 77 of the main body 73. An outer peripheral wall 78 is provided around the lid 74. The lid 74 has a protruding portion 79 that is substantially T-shaped in plan view. A positive external terminal 80P is fixed to one corner portion of the front portion of the lid 74, and a negative external terminal 80N is fixed to the other corner portion.

[0042] As shown in FIGS. 3A and 3B, the storage battery cell 30A houses an electrode body 83 together with a non-aqueous electrolyte in a rectangular parallelepiped case 82. The case 82 has a case main body 84 and a lid 85 that closes the opening above it. Although not shown in detail, the electrode body 83 has a separator made of a porous resin film disposed between a negative electrode element in which a negative electrode active material is applied to a base material made of copper foil and a positive electrode element in which a positive electrode active material is applied to a base material made of aluminum foil. All of these are in strip form, and are wound flatly so as to be accommodatable in the case main body 84 with the negative electrode element and the positive electrode element offset from each other in the width direction with respect to the separator.

[0043] A positive electrode terminal 87 is connected to the positive electrode element via a positive electrode current collector 86, and a negative electrode terminal 89 is connected to the negative electrode element via a negative electrode current collector 88. The positive electrode current collector 86 and the negative electrode current collector 88 each consist of a flat pedestal portion 90 and a leg portion 91 extending from this pedestal portion 90. A through hole is formed in the pedestal portion 90. The leg portion 91 is connected to the positive electrode element or the negative electrode element. The positive electrode terminal 87 and the negative electrode terminal 89 each consist of a terminal main body portion 92 and a shaft portion 93 protruding downward from the center portion of its lower surface. Among these, the terminal main body portion 92 and the shaft portion 93 of the positive electrode terminal 87 are integrally formed of aluminum (a single material). In the negative electrode terminal 89, the terminal main body portion 92 is made of aluminum and the shaft portion 93 is made of copper, and these are assembled. The terminal main body portions 92 of the positive electrode terminal 87 and the negative electrode terminal 89 are disposed at both ends of the lid 85 via gaskets 94 made of an insulating material, and are exposed outward from these gaskets 94.

[0044] As shown in FIG. 3A, the lid 85 has a pressure release valve 95. The pressure release valve 95 is located between the positive electrode terminal 87 and the negative electrode terminal 89. The pressure release valve 95 opens when the internal pressure of the case 82 exceeds a limit value to reduce the internal pressure of the case 82.

[0045] (3) Electrical Configuration of the Energy Storage Device As shown in FIG. 4, the energy storage device 1 includes a battery pack 30, a BMU 31 (an example of a management device), and a communication connector 32. The battery pack 30 is connected to the external terminal 80P of the positive electrode by the power line 34P and to the external terminal 80N of the negative electrode by the power line 34N. The battery pack 30 has 12 storage cells 30A connected in 3 parallel and 4 series. In FIG. 4, three storage cells 30A connected in parallel are represented by one battery symbol.

[0046] The BMU 31 includes a current sensor 33, a voltage sensor 35, a temperature sensor 36, and a management unit 37. The current sensor 33 is located on the negative electrode side of the battery pack 30 and is provided on the power line 34N of the negative electrode. The current sensor 33 measures the charge and discharge current [A] of the battery pack 30 and outputs it to the management unit 37. The voltage sensor 35 is connected to both ends of each storage cell 30A by signal lines respectively. The voltage sensor 35 measures the battery voltage [V] of each storage cell 30A and outputs it to the management unit 37. The total voltage [V] of the battery pack 30 is the total voltage of four storage cells 30A connected in series.

[0047] The temperature sensor 36 is a contact type or non-contact type, measures the temperature [°C] of the storage cell 30A, and outputs it to the management unit 37. Although omitted in FIG. 4, two or more temperature sensors 36 are provided. Each temperature sensor 36 measures the temperature of a different storage cell 30A. The management unit 37 uses, for example, the average value of the temperatures output from two or more temperature sensors 36 as the temperature of the power storage device 1.

[0048] The management unit 37 includes a microcomputer 37A in which a CPU, a RAM, etc. are integrated into one chip, a storage unit 37B, and a communication unit 37C. The microcomputer 37A manages the power storage device 1 by executing the management program stored in the storage unit 37B. The storage unit 37B is a storage medium capable of rewriting data, and stores the management program executed by the management unit 37 and various data described later. The communication unit 37C is a circuit for the BMU 31 to communicate with the vehicle ECU 14 (Engine Control Unit). The communication connector 32 is a connector to which a communication cable for the BMU 31 to communicate with the vehicle ECU 14 is connected.

[0049] (4) Various data The various data stored in the storage unit 37B includes the initial internal resistance value at the reference temperature (25 °C), the internal resistance increase rate, the temperature correction coefficient, etc. The internal resistance increase rate stored at the time of shipment of the power storage device 1 is, for example, 0%. The temperature correction coefficient is stored as a table in which a temperature correction coefficient corresponding to each temperature (for example, every 1 °C) of the power storage device 1 is associated. The temperature correction coefficient also varies depending on the state of charge (SOC: State Of Charge) of the power storage device 1. For this reason, a table of temperature correction coefficients is stored in the storage unit 37B for each SOC range. The SOC range refers to, for example, one section when dividing 0% to 100% into a plurality of sections with a width of 5%.

[0050] (5) Processes executed by the management unit The following processes executed by the management unit 37 will be described. · Judgment process for engine startability · Estimation process for average internal resistance value · Update process for internal resistance increase rate · Update process for temperature correction coefficient

[0051] (5-1) Judgment process for engine startability Conventionally, the power storage device 1 for engine start has often been maintained at a high SOC in order to ensure engine start at the time of engine start (also referred to as cranking). However, recent vehicles reduce the operation of the vehicle generator 13 as much as possible and increase the ratio of regenerative charging during braking to improve fuel efficiency. In this case, since the SOC is adjusted to leave room for regenerative acceptance according to the driving state, the voltage of the power storage device 1 decreases compared to the case where it is maintained at a high SOC.

[0052] When the voltage of the power storage device 1 drops, there is a possibility that the voltage required for cranking cannot be applied. Therefore, the management unit 37 determines whether the voltage required for cranking can be applied (in other words, whether the engine can be started). Specifically, the management unit 37 predicts the voltage drop amount during cranking, and if the predicted voltage drop amount is less than the voltage of the power storage device 1, it determines that cranking is possible, and if it is equal to or greater than the voltage of the power storage device 1, it determines that cranking is impossible.

[0053] Specifically, the prediction of the voltage drop amount during cranking will be described. The voltage drop amount [V] during cranking can be predicted by the following formula 2. Voltage drop amount = Internal resistance value × Maximum cranking current value × 10 -3 ··· Formula 2

[0054] In formula 2, the maximum cranking current value [A] is the maximum current value measured during cranking at the time of initial start. The maximum cranking current value may be the maximum current value measured during the previous cranking, or may be the average value of the maximum current values measured during the most recent multiple crankings. The above-mentioned formula 2 can be converted as follows into formula 3. The management unit 37 predicts the voltage drop amount according to the following formula 3.

Equation

[0055] The internal resistance increase rate shown in formula 3 is the internal resistance increase rate stored in the storage unit 37B. The internal resistance increase rate stored in the storage unit 37B is updated by the internal resistance increase rate update process described later. By predicting the voltage drop amount using the updated internal resistance increase rate, the voltage drop amount can be predicted reflecting the deterioration of the power storage device 1. In the update process of the internal resistance increase rate described later, the internal resistance increase rate is estimated using the average internal resistance value estimated by the average internal resistance value estimation process described later. If the estimation accuracy of the average internal resistance value is low, the estimation accuracy of the internal resistance increase rate decreases, and as a result, the prediction accuracy of the voltage drop amount also decreases. Therefore, in order to accurately predict the voltage drop amount, it is important to accurately estimate the average internal resistance value.

[0056] The temperature correction coefficient shown in Equation 3 is the temperature correction coefficient corresponding to the estimated value of the SOC and the temperature of the power storage device 1 at the time of predicting the voltage drop amount among the temperature correction coefficients stored in the storage unit 37B. Although it will be described in detail later, the temperature correction coefficient stored in the storage unit 37B is updated by the temperature correction coefficient update process described later.

[0057] (5-2) Estimation process of average internal resistance value In the average internal resistance value estimation process, the management unit 37 executes the estimation process, correction process, and averaging process described below. Hereinafter, an outline of these processes will be described, and then the flow of the average internal resistance value estimation process will be described.

[0058] The estimation process is a process of estimating the internal resistance value of the power storage device 1 based on the voltage drop amount measured by the voltage sensor 35 and the current increase amount measured by the current sensor 33 during the discharge of the power storage device 1. Generally, the voltage fluctuation of the power storage device 1 for engine starting is the largest during cranking. Since the internal resistance value can be estimated more accurately as the voltage fluctuation is larger, the management unit 37 estimates the internal resistance value during cranking.

[0059] The correction process is a process of obtaining a corrected internal resistance value, which is the internal resistance value at the reference temperature (25°C), by correcting the internal resistance value estimated in the estimation process based on the temperature correction coefficient corresponding to the estimated value of the SOC and the temperature. The averaging process is a process of estimating the average internal resistance value by averaging a plurality of corrected internal resistance values obtained by the correction process. In order to make it difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value, the management unit 37 performs a weighted average of the plurality of corrected internal resistance values according to the difference between the temperature at which each corrected internal resistance value is obtained and the reference temperature.

[0060] Referring to FIG. 5, the flow of the process for estimating the average internal resistance value will be described. This process is started every time cranking is performed. In S101, the management unit 37 measures the voltage drop amount (V1 - V2) and the current increase amount (I1 - I2) for several m seconds from the start of cranking.

[0061] In S102, the management unit 37 estimates the internal resistance value by the above-described formula 1 (an example of the fourth process). In S103, the management unit 37 reads out the temperature correction coefficient corresponding to the estimated value of the SOC and the temperature when the voltage drop amount and the current increase amount are measured in S101 from the storage unit 37B, and substitutes the internal resistance value estimated in S102 and the temperature correction coefficient into the following formula 4 to obtain the corrected internal resistance value (an example of the eighth process).

Equation

[0062] In S104, the management unit 37 stores the obtained corrected internal resistance value, the estimated value of the SOC when the voltage drop amount and the current increase amount are measured in S101, the temperature of the power storage device 1, and the date and time in the storage unit 37B. These pieces of information may be overwritten due to the storage capacity of the storage unit 37B. Therefore, the estimated values of the temperature and the SOC may be stored as a histogram.

[0063] In S105, the management unit 37 assigns scores to the obtained corrected internal resistance value from the following two viewpoints. The viewpoints for assigning scores are not limited to the following two and can be determined as appropriate. Viewpoint 1: The higher the corrected internal resistance value obtained from the internal resistance value estimated at a temperature with a small difference from the reference temperature (25°C), the higher the score is given. Table 1 below shows an example of the scores to be given. X5 > X4 > X3 > X2 > X1. Since the smaller the difference from the reference temperature, the higher the score, for temperatures lower than the reference temperature, the lower the temperature, the lower the score.

Table 1

[0064] Viewpoint 2: The higher the corrected internal resistance value in the temperature range where the internal resistance value is estimated more frequently, the higher the score is given. Specifically, for example, the management unit 37 divides the temperature of the power storage device 1 into a plurality of temperature ranges every 5°C, and totals the number of corrected internal resistance values obtained in that temperature range for each temperature range. The management unit 37 sets the higher the corrected internal resistance value obtained in the temperature range with the larger number of obtained corrected internal resistance values.

[0065] In S106, the management unit 37 estimates the average internal resistance value by weighted-averaging the corrected internal resistance value according to the score, as shown in Equation 5 below (an example of the ninth process). In Equation 5, DCRn (n is an integer of 1 or more) is the corrected internal resistance value, and Wn is the score.

Equation

[0066] (5-3) Update process of internal resistance increase rate The update process of the internal resistance increase rate is a process of updating the internal resistance increase rate stored in the storage unit 37B based on the average internal resistance value estimated in the average internal resistance value estimation process. Referring to FIG. 6, the flow of the update process of the internal resistance increase rate will be described. This process starts when the average internal resistance value is estimated by the average internal resistance value estimation process.

[0067] In S201, the management unit 37 estimates the internal resistance increase rate by the following Equation 6 (an example of the tenth process).

Equation

[0068] In S202, the management unit 37 obtains the fluctuation rate of the internal resistance increase rate estimated in S201 with respect to the internal resistance increase rate stored in the storage unit 37B according to the following formula 7.

Equation

[0069] In S203, the management unit 37 determines whether or not the fluctuation rate is equal to or less than a predetermined value. If the fluctuation rate estimated in S202 is high, the estimation accuracy of the average internal resistance value estimated in the average internal resistance value estimation process may be low. Therefore, the management unit 37 determines whether or not the fluctuation rate is equal to or less than a predetermined value. If it is equal to or less than the predetermined value, the process proceeds to S204, and if it is greater than the predetermined value, the process ends. Here, the case of determining whether or not the fluctuation rate is equal to or less than a predetermined value will be described as an example, but it may be determined whether or not the absolute value of the difference between the internal resistance increase rate estimated in S201 and the internal resistance increase rate stored in the storage unit 37B is equal to or less than a predetermined value.

[0070] In S204, the management unit 37 updates the internal resistance increase rate stored in the storage unit 37B with the internal resistance increase rate estimated in S201 (an example of the 11th process).

[0071] (5-4) Update Process of Temperature Correction Coefficient The update process of the temperature correction coefficient is a process of updating the temperature correction coefficient stored in the storage unit 37B according to the deterioration of the power storage device 1. Referring to FIG. 7, the flow of the update process of the temperature correction coefficient will be described. This process starts when cranking is performed after the internal resistance increase rate is updated by the update process of the internal resistance increase rate.

[0072] In S301, the management unit 37 measures the voltage drop amount during cranking by the voltage sensor 35 (an example of the 1st process). In S302, the management unit 37 measures the amount of current increase during cranking by means of the current sensor 33 (an example of the second process). In S303, the management unit 37 measures the temperature during cranking by means of the temperature sensor 36 (an example of the third process).

[0073] In S304, the management unit 37 estimates the internal resistance value of the power storage device 1 by substituting the voltage drop amount measured in S301 and the amount of current increase measured in S302 into the above-mentioned formula 1 (an example of the fourth process). In S305, the management unit 37 predicts the voltage drop amount by means of the above-mentioned formula 3 (an example of the seventh process). Specifically, the management unit 37 predicts the voltage drop amount by substituting the temperature correction coefficient, the initial internal resistance value, the internal resistance increase rate, and the maximum cranking current value measured in the past, which are stored in the storage unit 37B in association with the temperature measured in S303, into formula 3.

[0074] In S306, the management unit 37 determines whether or not the difference between the actual voltage drop amount measured in S301 and the predicted voltage drop amount in S305 is equal to or greater than a reference value. If the difference is less than the reference value, it can be said that the temperature correction coefficient stored in the storage unit 37B is generally appropriate. In that case, it is not always necessary to update the temperature correction coefficient. Therefore, when the difference is equal to or greater than the reference value, the management unit 37 proceeds to S307, and when the difference is less than the reference value, the process ends. The above-mentioned reference value is set in consideration of the detection accuracy of the voltage sensor 35, the current sensor 33, the temperature sensor 36, etc., the target estimation accuracy of the average internal resistance value, the target accuracy of determining whether the engine can be started, etc.

[0075] In S307, the management unit 37 obtains an updated value of the temperature correction coefficient corresponding to the temperature measured in S303 based on the internal resistance value estimated in S304 and the internal resistance value at the reference temperature (an example of the fifth process). Specifically, the management unit 37 obtains the updated value using the following formula 8. In formula 8, the internal resistance value at the reference temperature is obtained from the initial internal resistance value and the internal resistance increase rate.

Equation

[0076] In S308, the management unit 37 determines whether the number of times the difference between the updated value obtained in S307 and the temperature correction coefficient stored in the storage unit 37B is equal to or greater than a predetermined value is equal to or greater than a predetermined number of times within a predetermined period during which the power storage device 1 can be regarded as not being deteriorated. The predetermined period is determined from the characteristics of the aging deterioration (so-called calendar deterioration) of the power storage device 1 and the like. Generally, since the power storage device 1 deteriorates faster at higher temperatures, the temperature may be recorded at regular intervals, and the predetermined period may be made variable according to the temperature. When the above-mentioned number of times is equal to or greater than the predetermined number of times, the management unit 37 proceeds to S309, and when it is less than the predetermined number of times, the process ends.

[0077] In S309, the management unit 37 updates the temperature correction coefficient stored in the storage unit 37B with the updated value obtained in S307 (an example of the sixth process). The management unit 37 may perform interpolation by the following interpolation or extrapolation in S309. Interpolation: Interpolate the temperature correction coefficient between the actually measured temperatures. For example, even if only 0°C and 25°C have been actually measured, the temperature correction coefficient at 5°C may be interpolated from the temperature correction coefficient at 0°C and the temperature correction coefficient at 25°C. Extrapolation: Interpolate the temperature correction coefficient outside the actually measured temperatures. For example, even if only 0°C and 25°C have been actually measured, the temperature correction coefficient at -5°C may be interpolated from the temperature correction coefficient at 0°C and the temperature correction coefficient at 25°C.

[0078] (6) Effects of the Embodiment According to the BMU 31, since the temperature correction coefficient is obtained based on the internal resistance value estimated in S304 (the fourth process) and the internal resistance value at the reference temperature, the temperature correction coefficient can be updated according to the deterioration of the power storage device 1. When the temperature correction coefficient is updated according to the deterioration of the power storage device 1, it is possible to suppress a decrease in the prediction accuracy of the charge and discharge power such as whether the engine can be started even when the power storage device 1 deteriorates. That is, according to the BMU 31, even if an error occurs in the temperature correction coefficient stored in the memory unit 37B, optimization by learning becomes possible. Since the temperature correction coefficient is also used for predicting the voltage drop amount during cranking, highly accurate prediction becomes possible when the temperature correction coefficient is optimized. If the voltage drop amount is larger than expected, there is a possibility that the power supply of the device connected to the power storage device 1 will be lost. According to the BMU 31, since the possibility of power supply loss can be reduced by accurately predicting the voltage drop amount, a highly reliable power storage device 1 can be provided.

[0079] According to the BMU 31, since the internal resistance value at the reference temperature is obtained based on the initial internal resistance value and the internal resistance increase rate, the deterioration of the power storage device is reflected in the internal resistance value at the reference temperature. For this reason, the temperature correction coefficient can be obtained more appropriately according to the deterioration of the power storage device.

[0080] According to the BMU 31, when the difference between the actual voltage drop amount measured in S301 (the first process) and the predicted voltage drop amount in S305 (an example of the seventh process) is less than the reference value, the temperature correction coefficient is not updated, so that the temperature correction coefficient can be prevented from being updated uselessly.

[0081] According to the BMU 31, when the number of times the difference between the updated value obtained in S307 (an example of the fifth process) and the temperature correction coefficient stored in the memory unit 37B is equal to or greater than a predetermined value is equal to or greater than a predetermined number of times, the temperature correction coefficient is updated, so that it is possible to prevent the temperature correction coefficient from being updated erroneously due to the influence of some error.

[0082] According to the BMU 31, since the average internal resistance value is estimated by weighted-averaging a plurality of corrected internal resistance values according to the difference between the temperature at which each corrected internal resistance value is obtained and the reference temperature, it becomes difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value. For this reason, it is possible to suppress a decrease in the estimation accuracy when estimating the average internal resistance value using the temperature correction coefficient. When the average internal resistance value is estimated by weighted averaging according to the difference between the temperature at which each corrected internal resistance value is obtained and the reference temperature, the internal resistance value estimated in summer can be actively used to estimate the average internal resistance value, so that the estimation accuracy of the internal resistance increase rate is improved. Regarding the update of the temperature correction coefficient, the internal resistance value estimated from autumn to winter is also used, so that the correction of the temperature correction coefficient when the temperature is low can also be realized.

[0083] According to the BMU31, a higher score is given to the corrected internal resistance value obtained at a temperature with a smaller difference from the reference temperature, and the corrected internal resistance values are weighted and averaged according to the scores. Therefore, it becomes difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value. For this reason, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0084] According to the BMU31, a higher score is given to the corrected internal resistance value in the temperature range where the number of times the corrected internal resistance value is obtained is large. Since the number of corrected internal resistance values obtained in the temperature range where the number of times the corrected internal resistance value is obtained is large is large, the influence of the measurement error of the temperature sensor 36 is reduced by averaging. For this reason, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the measurement error of the temperature sensor 36.

[0085] According to the BMU31, when the change rate of the internal resistance increase rate estimated in S201 (the tenth process) with respect to the internal resistance increase rate stored in the storage unit 37B is equal to or less than a predetermined value, or when the difference between the internal resistance increase rate stored in the storage unit 37B and the internal resistance increase rate estimated in S202 is equal to or less than a predetermined value, the internal resistance increase rate stored in the storage unit 37B is updated with the internal resistance increase rate estimated in S202 (the eleventh process). For this reason, it is possible to suppress the internal resistance increase rate stored in the storage unit 37B from being updated by the internal resistance increase rate estimated using the average internal resistance value with low estimation accuracy.

[0086] <Embodiment 2> The management unit 37 according to Embodiment 2 uses only the corrected internal resistance value when the temperature when the corrected internal resistance value is obtained is equal to or higher than a predetermined lower limit temperature. In other words, the management unit 37 according to Embodiment 2 does not use the corrected internal resistance value estimated when the temperature is lower than the predetermined lower limit temperature for estimating the average internal resistance value.

[0087] As an example, consider the case where the lower limit temperature is set to -5°C in consideration of the temperature dependency in FIG. 8. FIG. 9 shows the daily minimum temperature and maximum temperature in 2019 in a certain city belonging to a subarctic climate. In the example shown in FIG. 9, although there is a period when the minimum temperature is -5°C, the problem of being unable to estimate the average internal resistance value over a long period does not occur. Generally, the deterioration of the power storage cell 30A does not progress rapidly in a -5°C environment, so even if the estimation frequency of the average internal resistance value decreases, no inconvenience occurs.

[0088] If the average internal resistance value is used using the corrected internal resistance value estimated at a low temperature, the estimation accuracy of the average internal resistance value decreases, and thus the estimation accuracy of the internal resistance increase rate also decreases. If the estimation accuracy of the internal resistance increase rate is low, the temperature correction coefficient cannot be appropriately corrected. For this reason, it is desirable to set the lower limit temperature so that the estimation accuracy of the average internal resistance value does not decrease.

[0089] By a similar method, an upper limit temperature may also be provided on the high temperature side, and the corrected internal resistance value estimated when the temperature is equal to or higher than the upper limit temperature may not be used for estimating the average internal resistance value.

[0090] According to the BMU 31 according to Embodiment 2, since the corrected internal resistance value obtained when the temperature is lower than the predetermined lower limit temperature is not used for estimating the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0091] <Embodiment 3> In the above-described Embodiment 2, the average internal resistance value is estimated using only the corrected internal resistance value estimated when the temperature is equal to or higher than a predetermined lower limit temperature. In contrast, the management unit 37 according to Embodiment 3 estimates the average internal resistance value using only the corrected internal resistance value estimated at the temperatures that account for a predetermined upper percentage of the temperatures at which the internal resistance value was estimated.

[0092] For example, when operating the storage cell 30A in a region colder than the subarctic climate, the management unit 37 records the temperature at regular intervals and estimates the average internal resistance value using only the corrected internal resistance value estimated at the temperatures that account for a predetermined upper percentage of the temperatures measured in the past during a predetermined period. For example, as shown in FIG. 10, when using the upper 80% of the temperatures measured in the past one year, the lower limit temperature can be determined to be 12°C.

[0093] In a similar manner, on the high-temperature side, the average internal resistance value may be estimated using only the corrected internal resistance value estimated at the temperatures that account for a predetermined lower percentage of the temperatures at which the internal resistance value was estimated.

[0094] According to the BMU 31 according to Embodiment 3, since it becomes difficult for the corrected internal resistance value obtained when the temperature is low to be reflected in the average internal resistance value, it is possible to suppress a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained when the temperature is low.

[0095] <Other Embodiments> The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

[0096] (1) In the above embodiment, the case where a higher score is given to the corrected internal resistance value estimated at a temperature with a smaller difference from the reference temperature has been described as an example. In this case, for the corrected internal resistance value estimated at a temperature higher than the reference temperature, a higher score is given as the difference from the reference temperature is smaller. In other words, the higher the temperature, the lower the score. On the other hand, since the corrected internal resistance value estimated at a temperature higher than the reference temperature is less likely to affect the deterioration of the estimation accuracy of the average internal resistance value, a score may be uniformly given for temperatures higher than the reference temperature. For the corrected internal resistance value estimated at a temperature lower than the reference temperature, a higher score may be given within a range lower than the score given at a higher temperature, with the score increasing as the difference from the reference temperature decreases.

[0097] (2) In the above embodiment, the case where a higher score is given to the corrected internal resistance value estimated at a temperature with a smaller difference from the reference temperature, and the corrected internal resistance value is weighted and averaged according to the score was described as an example. In contrast, only the corrected internal resistance values with scores equal to or higher than the reference value may be simply averaged or weighted and averaged. In other words, the corrected internal resistance values with scores lower than the reference value may not be used in the calculation of the average internal resistance value. By doing so, since it becomes difficult for the corrected internal resistance value obtained at a low temperature to be reflected in the average internal resistance value, a decrease in the estimation accuracy of the average internal resistance value caused by the corrected internal resistance value obtained at a low temperature can be suppressed.

[0098] (3) In the above embodiment, the case where all the obtained corrected internal resistance values are used for estimation when estimating the average internal resistance value was described as an example. In contrast, the management unit 37 may estimate using only the corrected internal resistance values obtained within a predetermined time in the past based on the current time.

[0099] (4) In the above embodiment, when the management unit 37 estimates the internal resistance value in the estimation process of the average internal resistance value, it may determine whether the state of the power storage device 1 is stable, and estimate the internal resistance value only when it is stable. For example, the internal resistance value may be estimated when at least one of the following four conditions is satisfied. Condition 1: The temperature of the power storage device 1 is stable. Condition 2: The polarization of the power storage device 1 has converged. Condition 3: There is no variation in the estimated values of the SOC among the power storage cells 30A. Condition 4: There is a low possibility of a large estimation error occurring in the estimated value of the SOC. Alternatively, the management unit 37 may assign a higher score as the number of satisfied conditions among these four conditions is larger.

[0100] (5) In the above embodiment, the case of assigning scores from two perspectives in S105 has been described as an example. In addition to or instead of these, scores may be assigned from the following perspective 3. Perspective 3: When the estimated value of the SOC is within the normal use range, a high score is given, and when it is outside the normal use range, a low score is given. In the case of the power storage device 1 for engine starting, the normal use range is, for example, the range where the SOC is from 50% to 90%. The range from 50% to 90% is an example, and the normal use range varies depending on the type of the power storage device 1 and the purpose of use.

[0101] (6) In the above embodiment, when estimating the average internal resistance value, the following two conditions are not judged. However, when the following two conditions are satisfied, the internal resistance increase rate may be estimated, and when they are not satisfied, the estimation may not be performed. Condition 1: The number of corrected internal resistance values used for estimating the average internal resistance value has reached a predetermined number. Condition 2: The update cycle of the internal resistance increase rate has been reached.

[0102] (7) The temperature correction coefficient in the above embodiment is stored as a table in which temperature and the temperature correction coefficient are associated. In contrast, it may be stored as a multi-dimensional table in which the temperature correction coefficient is associated with temperature, the estimated value of the SOC, and the maximum current value. In the case of a multi-dimensional table, the update of the temperature correction coefficient by learning may be performed by considering only temperature, or may be performed by considering the estimated value of the SOC and the maximum current value as well.

[0103] (8) In the above embodiment, the lithium-ion secondary battery has been described as an example of the power storage cell 30A. However, the power storage cell 30A may be a capacitor involving an electrochemical reaction.

Explanation of Reference Numerals

[0104] 1: Power storage device 31: BMU (an example of a management device) 32: Communication connector 33: Current sensor 35: Voltage sensor 36: Temperature sensor 37: Management unit 37B: Memory unit

Claims

1. A management device for a power storage device, a voltage sensor that measures the voltage of the power storage device, a current sensor that measures the current of the power storage device, a temperature sensor that measures the temperature of the power storage device, a storage unit in which a temperature correction coefficient for correcting the internal resistance value of the power storage device to the internal resistance value at a reference temperature is stored in association with the temperature, a management unit, comprising: The management unit, a first process of measuring the voltage drop amount during discharge of the power storage device by the voltage sensor, a second process of measuring the current increase amount during discharge of the power storage device by the current sensor, a third process of measuring the temperature during discharge of the power storage device by the temperature sensor, a fourth process of estimating the internal resistance value of the power storage device based on the voltage drop amount measured in the first process and the current increase amount measured in the second process, a fifth process of obtaining a temperature correction coefficient corresponding to the temperature measured in the third process based on the internal resistance value estimated in the fourth process and the internal resistance value at the reference temperature, a sixth process of updating the temperature correction coefficient stored in the storage unit and associated with the temperature measured in the third process with the temperature correction coefficient obtained in the fifth process, A management device for a power storage device that executes the above.

2. The management device for a power storage device according to claim 1, wherein the storage unit stores an initial internal resistance value at a reference temperature and an internal resistance increase rate, and the management unit obtains the internal resistance value at the reference temperature based on the initial internal resistance value and the internal resistance increase rate stored in the storage unit in the fifth process. A management device for a power storage device.

3. The management device for a power storage device according to claim 1 or claim 2, wherein the management unit, executes a seventh process of predicting the voltage drop amount during discharge of the power storage device based on the temperature correction coefficient stored in the storage unit and associated with the temperature measured in the third process, and in the sixth process, when the difference between the voltage drop amount predicted in the seventh process and the voltage drop amount measured in the first process is equal to or greater than a reference value, updates the temperature correction coefficient stored in the storage unit. A management device for a power storage device.

4. The management device for a power storage device according to any one of claims 1 to 3, In the sixth process, the management unit updates the temperature correction coefficient stored in the storage unit when the number of times the difference between the temperature correction coefficient obtained in the fifth process and the temperature correction coefficient stored in the storage unit is equal to or greater than a predetermined value within a predetermined period during which the power storage device can be regarded as not being deteriorated is equal to or greater than a predetermined number of times. A management device for a power storage device.

5. A management device for a power storage device according to claim 2, wherein the management unit performs an eighth process of obtaining a corrected internal resistance value by correcting the internal resistance value estimated by the fourth process based on a temperature correction coefficient associated with the temperature measured in the third process, a ninth process of estimating an average internal resistance value by weighted-averaging a plurality of corrected internal resistance values obtained in the eighth process according to the difference between the temperature at which each corrected internal resistance value was obtained and a reference temperature, a tenth process of estimating an internal resistance increase rate of the power storage device based on the average internal resistance value estimated in the ninth process, and an eleventh process of updating the internal resistance increase rate stored in the storage unit with the internal resistance increase rate estimated in the tenth process. A management device for a power storage device that executes the above processes.

6. A management device for a power storage device according to claim 5, wherein the management unit estimates an average internal resistance value using only the corrected internal resistance values whose obtained temperature is equal to or higher than a predetermined lower limit temperature in the ninth process. A management device for a power storage device.

7. A management device for a power storage device according to claim 5, wherein the management unit estimates an average internal resistance value using only the corrected internal resistance values obtained at temperatures that are a predetermined upper percentage of the temperatures at which the corrected internal resistance values are obtained in the ninth process. A management device for a power storage device.

8. A management device for a power storage device according to any one of claims 5 to 7, wherein the management unit assigns a higher score to the corrected internal resistance value obtained at a temperature with a smaller difference from the reference temperature in the ninth process, and weighted-averages the corrected internal resistance values according to the scores. A management device for a power storage device.

9. A management device for a power storage device according to any one of claims 5 to 7, wherein the management unit assigns a higher score to the corrected internal resistance value obtained at a temperature with a smaller difference from the reference temperature in the ninth process, and weighted-averages only the corrected internal resistance values whose scores are equal to or higher than a reference value. A management device for a power storage device.

10. A management device for a power storage device according to any one of claims 5 to 9, wherein in the ninth process, the management unit assigns a higher score to the corrected internal resistance value in a temperature range where the number of times the corrected internal resistance value is obtained is large, and weights and averages the corrected internal resistance values according to the scores, the management device for a power storage device.

11. A management device for a power storage device according to any one of claims 5 to 10, wherein in the eleventh process, when the rate of change of the internal resistance increase rate estimated in the tenth process with respect to the internal resistance increase rate stored in the storage unit is equal to or less than a predetermined value, or when the difference between the internal resistance increase rate stored in the storage unit and the internal resistance increase rate estimated in the tenth process is equal to or less than a predetermined value, the management unit updates the internal resistance increase rate stored in the storage unit with the internal resistance increase rate estimated in the tenth process, the management device for a power storage device.

12. A method for managing a power storage device, comprising: a first step of measuring, by a voltage sensor, a voltage drop amount during discharge of the power storage device; a second step of measuring, by a current sensor, a current increase amount during discharge of the power storage device; a third step of measuring, by a temperature sensor, a temperature during discharge of the power storage device; a fourth step of estimating an internal resistance value of the power storage device based on the voltage drop amount measured in the first step and the current increase amount measured in the second step; a fifth step of obtaining a temperature correction coefficient corresponding to the temperature measured in the third step based on the internal resistance value estimated in the fourth step and the internal resistance value at a reference temperature; a sixth step of updating the temperature correction coefficient stored in the storage unit and associated with the temperature measured in the third step with the temperature correction coefficient obtained in the fifth step. A method for managing a power storage device, including the above steps.

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