Battery full charge capacity estimation method and full charge capacity estimation device

Abstract

To improve the full charge capacity estimation accuracy.SOLUTION: A full charge capacity estimation method includes a step A of acquiring battery data and processing the acquired data, a step B of extracting data, and a step C of estimating the full charge capacity of a battery to be measured. The step A includes acquiring battery data including a voltage value, a current value, and a temperature value, which can be obtained over time from the battery to be measured, and processing the acquired data. The step B includes extracting data equal to or greater than n satisfying a predetermined condition from at least one of the acquired data in the step A and the data obtained by the processing in the step A. The step C includes estimating the full charge capacity of the battery to be measured on the basis of the data extracted in the step B. Here, n is an integer equal to or greater than 3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for estimating a full charge capacity of a battery. [Background technology]

[0002] International Publication No. 2012 / 105492 discloses a method for detecting the full charge capacity of a battery, which includes a capacity change detection step, an open circuit voltage detection step, a remaining capacity determination step, a remaining capacity change value calculation step, and a full charge capacity calculation step. In the full charge capacity detection method disclosed in this publication, when at least one of the capacity change value detected in the capacity change detection step, the remaining capacity change value calculated in the remaining capacity change value calculation step, and the voltage difference between the first open circuit voltage and the second open circuit voltage detected in the open circuit voltage detection step is greater than a preset value, the full charge capacity of the battery is calculated based on the capacity change value and the remaining capacity change value. It is said that this full charge capacity detection method can detect the full charge capacity of the battery more accurately.

[0003] International Publication WO 2012 / 120620 discloses a battery state estimation method that measures the current value and terminal voltage value of a battery during battery charging and discharging, and calculates the battery state based on the measured current value and terminal voltage value. In the battery state estimation method disclosed in the publication, if the change in the measured current value per second is equal to or greater than a predetermined value, the current and terminal voltage measured during a period from the occurrence of the current change until a predetermined time has elapsed are not used. The battery state is calculated based on the current value and terminal voltage value measured during a battery charging and discharging period other than the above period. In the battery state estimation method disclosed in the publication, at least one of the charging rate, deterioration degree, and full charge capacity is calculated as the battery state. It is said that this battery state estimation method can estimate the battery state, such as the capacity and deterioration degree, with high accuracy during discharging. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2012 / 105492 [Patent Document 2] International Publication No. 2012 / 120620 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors wish to improve the accuracy of estimating the full charge capacity of a battery. [Means for solving the problem]

[0006] The method for estimating the full charge capacity of a battery disclosed herein includes step A, which includes acquiring battery data and processing the acquired data, step B, which extracts data, and step C, which estimates the full charge capacity of a battery to be measured. Step A includes acquiring battery data, including voltage values, current values, and temperature values, obtained over time from the battery to be measured, and processing the acquired data. Step B includes extracting n or more pieces of data that satisfy a predetermined condition from at least one of the data acquired in step A and the data obtained by the processing in step A. Step C estimates the full charge capacity of the battery to be measured based on the data extracted in step B, where n is an integer equal to or greater than 3. According to this method for estimating the full charge capacity of a battery, the accuracy of estimating the full charge capacity of a battery is improved. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a battery system 100. As shown in FIG. [Diagram 2] FIG. 2 is a flowchart showing a flow executed by the control device 40 of the full-charge capacity estimation device 20. As shown in FIG. [Diagram 3] FIG. 3 is a circuit diagram showing a voltage behavior model 60 of the battery 1. [Figure 4] FIG. 4 is a graph showing the relationship between the open circuit voltage OCV and the SOC. [Diagram 5]FIG. 5 is a graph showing the relationship between the current integrated value of the extracted data D and the SOC. [Figure 6] FIG. 6 is a flowchart showing a flow executed by the control device 40 of the full-charge capacity estimation device 20. [Figure 7] FIG. 7 is a graph showing the relationship between the current integrated value and the SOC of the narrowed-down data D1. [Figure 8] FIG. 8 is a flowchart showing a flow executed by the control device 40 of the full-charge capacity estimation device 20. [Figure 9] FIG. 9 is a graph showing the relationship between the SOC and the current integrated value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiment described herein is, of course, not intended to limit the present invention in particular. Each drawing is drawn typically and does not necessarily reflect the actual product. Furthermore, the same reference numerals are appropriately used for members and parts that perform the same function, and duplicated descriptions are appropriately omitted.

[0009] <Battery System 100> Fig. 1 is a schematic diagram showing a battery system 100. As shown in Fig. 1, the battery system 100 includes a battery 1 and a full charge capacity estimation device 20. The battery 1 is connected to an external load (not shown).

[0010] In this specification, the term "battery" refers to a storage device capable of extracting electric energy. The battery includes a secondary battery that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte, and includes, for example, a lithium ion secondary battery. The form of use of the battery is not particularly limited. The battery includes a battery pack in which a plurality of batteries (single cells) are electrically connected to each other. The battery may be, for example, a so-called in-vehicle battery that serves as a power source for an electric vehicle. When the battery is used as an in-vehicle battery, the battery is appropriately connected to a charging / discharging device and charged. The battery may be discharged while connected to the charging / discharging device. The battery may be a so-called stationary battery that is installed in a general home, a business, etc. When the battery is used as a stationary battery, the battery may be connected to a power generation device, a system power, etc.

[0011] The full charge capacity F of the battery 1 decreases over time as the battery 1 is charged and discharged. The full charge capacity F is the battery capacity until the battery 1, which has been charged to a maximum charge capacity of 100% SOC (States Of Charge), is completely discharged. The full charge capacity estimation device 20 estimates the full charge capacity F of the battery 1.

[0012] The full charge capacity estimation device 20 includes a sensor 30 and a control device 40. The sensor 30 includes a voltage sensor 31, a current sensor 32, and a temperature sensor 33. The control device 40 includes an acquisition unit 41, a first calculation unit 42, a first estimation unit 43, a first determination unit 44, a second determination unit 45, a third determination unit 46, a second estimation unit 47, a determination unit 48, a second calculation unit 49, a third estimation unit 50, a fourth determination unit 51, a fifth determination unit 52, and a storage unit 53. The control device 40 may be, for example, a computer such as an ECU (Electronic Control Unit) or a circuit board equipped with a microcomputer. The computer performs required functions, for example, according to a predetermined program. Each function of the computer is processed by the cooperation of the computer's arithmetic unit (also called a processor, CPU (Central Processing Unit), or MPU (Micro-Processing Unit)) and storage device (memory, hard disk, etc.) and software. In this embodiment, the control device 40 is realized by an ECU. Each of the units 41 to 53 of the control device 40 may be realized by one or more processors, or may be incorporated into a circuit. The control device 40 is configured to be able to communicate with the sensor 30. The storage unit 53 may store a previously estimated full charge capacity Fp, etc.

[0013] A method for estimating the full charge capacity F of the battery 1 using the full charge capacity estimation device 20 will be described below together with the configuration of the full charge capacity estimation device 20. The method for estimating the full charge capacity F of the battery disclosed herein includes a step A including acquiring data of the battery 1 and processing the acquired data, a step B of extracting data D that satisfies a predetermined condition, and a step C of estimating the full charge capacity F of the battery 1. Fig. 2 is a flowchart showing a flow executed by the control device 40 of the full charge capacity estimation device 20. Fig. 2 shows the flow of the method for estimating the full charge capacity F of the battery 1 as an in-vehicle battery.

[0014] When the ignition switch of the vehicle is turned on, the process shown in Fig. 2 is started. In step S1, the current integrated value and the SOC calculated when the ignition switch was turned on the previous time are reset, or a part of the stored data is reset.

[0015] <Process A for acquiring data on battery 1 and processing the acquired data> In this embodiment, step A includes acquiring data on battery 1 including current, voltage and temperature values ​​(step S2 in FIG. 2), calculating an integrated current value and obtaining an estimated SOC value (step S3 in FIG. 2).

[0016] In step S2, the acquisition unit 41 acquires data of the battery 1. The acquisition unit 41 acquires data when the battery 1 is being charged and discharged, including when the vehicle is running and traveling. The acquisition unit 41 acquires data while the vehicle is running and also when the battery 1 is at rest when no current flows through the battery 1. The data of the battery 1 includes a current value, a voltage value, and a temperature value. The acquisition unit 41 acquires the current value, voltage value, and temperature value detected by the sensor 30 as data.

[0017] The voltage sensor 31 of the sensor 30 detects the voltage value of the battery 1. The current sensor 32 detects the current value when the battery 1 is charged and discharged. The temperature sensor 33 detects the temperature value of the battery 1. Here, the battery 1 may be an assembled battery in which a plurality of unit cells are electrically connected to each other. When the battery 1 is an assembled battery, a plurality of temperature sensors 33 and voltage sensors 31 may be provided. When the battery 1 is an assembled battery, one temperature sensor 33 and voltage sensor 31 may be provided for the plurality of unit cells, or a temperature sensor 33 and voltage sensor 31 may be provided for each unit cell. When one temperature sensor 33 is provided for the plurality of unit cells, the temperature value of each unit cell may be estimated by calculation. When the batteries 1 are connected in parallel, one voltage sensor 31 may be provided for the batteries 1 connected in parallel. When the batteries 1 are connected in parallel, a current sensor 32 may be provided for each battery 1 connected in parallel. The voltage sensor 31, current sensor 32, and temperature sensor 33 detect the detected battery 1 current value, voltage value, and temperature value, respectively, as analog signals.

[0018] Data is detected over time from the battery 1 to be measured. Here, the voltage sensor 31, the current sensor 32, and the temperature sensor 33 can detect the voltage value, the current value, and the temperature value at predetermined intervals, respectively. Although not particularly limited, the intervals for detecting the voltage value, the current value, and the temperature value can be set to, for example, about 0.001 to 1 second (about 0.01 to 1 second). The intervals for detecting the voltage value, the current value, and the temperature value may be set to, for example, a constant interval. The detected analog signal is converted into a digital signal by an A / D converter and output to the acquisition unit 41 of the control device 40. The acquisition unit 41 acquires the data in association with time.

[0019] In step S3, the first calculation unit 42 calculates an integrated current value from the data acquired by the acquisition unit 41. The first calculation unit 42 calculates the integrated current value by integrating the current values ​​included in the data. Here, the integrated current value is calculated using the following formula (1): Accumulated current value = Accumulated current value calculated up to the previous time + ΔT × current value (1) Here, ΔT is the time between the time when the current value was measured last time and the time when the current value is measured this time. In step S3, the first estimation unit 43 estimates the SOC from the acquired data. The first estimation unit 43 obtains an estimated value of the SOC based on the data of the battery 1. In this embodiment, the first estimation unit 43 obtains an estimated value of the SOC based on the data of the battery 1 and a predetermined voltage behavior model.

[0020] In the voltage behavior model, the internal resistance of the battery, the behavior of the charge / discharge current, and the behavior of the battery voltage are modeled using an equivalent circuit. Here, the SOC of the battery 1 is estimated based on the voltage behavior model from the acquired voltage (closed circuit voltage CCV) of the battery 1. As the voltage behavior model for estimating the SOC, a conventionally known battery voltage behavior model such as a CR parallel circuit may be used. Note that the battery voltage behavior model used is not limited to the form described below. The battery voltage behavior model may be set appropriately depending on the configuration of the battery 1.

[0021] Fig. 3 is a circuit diagram showing a voltage behavior model 60 of the battery 1. In Fig. 3, the directions of a current I flowing through a voltage source 61, a current Ia flowing through a capacitor 63a, and a current Ib flowing through an internal resistance 63b are indicated by arrows. As shown in Fig. 3, the voltage behavior model 60 includes a voltage source 61, an internal resistance 62, and a CR parallel circuit 63, which are connected in series in this order. The CR parallel circuit 63 is a circuit in which a capacitor 63a and an internal resistance 63b are connected in parallel. In the voltage behavior model 60, an open circuit voltage OCV of the voltage source 61 is estimated.

[0022] The open circuit voltage OCV of the voltage source 61 is estimated based on an estimated polarization voltage (Vp+Vohm) consisting of a closed circuit voltage CCV (Closed Circuit Voltage) applied to the voltage behavior model 60, an estimated voltage drop Vohm caused by the internal resistance 62, and an estimated voltage drop Vp caused in the CR parallel circuit 63. The open circuit voltage OCV of the voltage source 61 is, for example, calculated using the following formula (2): OCV=CCV-Vohm-Vp (2) Here, the estimated value Vohm of the voltage drop caused by the internal resistance 62 can be calculated by the product of the resistance value Rohm of the internal resistance 62 and the current value I flowing through the voltage behavior model 60. The estimated value (Vp+Vohm) of the polarization voltage can be calculated by adding the product of the resistance value Rp of the internal resistance 63b and the current value Ib flowing through the internal resistance 63b to the product of the resistance value Rohm of the internal resistance 62 and the current value I flowing through the internal resistance 62. Other known general electric circuit calculation methods for calculating the voltage value of a CR circuit can also be used. In this way, the open circuit voltage OCV of the voltage source 61 is estimated.

[0023] The resistance value Rohm of the internal resistor 62 used to estimate the estimated value Vohm of the voltage drop used to estimate the open circuit voltage OCV, the resistance value Rp of the internal resistor 63b used to estimate the estimated value Vp of the voltage drop occurring in the CR parallel circuit 63, and the capacitance C of the capacitor 63a may vary depending on the SOC and temperature value of the battery 1. The resistance values ​​Rohm, Rp, and capacitance C may be appropriately corrected depending on the SOC and temperature value of the battery 1. For example, a two-dimensional table of temperature value and SOC may be provided for each of the resistance values ​​Rohm, Rp, and capacitance C. The resistance values ​​Rohm, Rp, and capacitance C may be determined by the temperature value measured by the temperature sensor 33, the SOC calculated separately, and the two-dimensional table of temperature value and SOC, and may be used to estimate the open circuit voltage OCV described above. This can improve the accuracy of the estimation of the open circuit voltage OCV.

[0024] By using the voltage behavior model 60, the open circuit voltage OCV of the battery 1 is estimated based on the voltage value of the battery 1. Then, the SOC of the battery 1 is estimated based on the estimated open circuit voltage OCV. In this embodiment, the SOC of the battery 1 is estimated using an OCV-SOC conversion table stored in advance in the control device 40. The OCV-SOC conversion table may be obtained in advance by a test, a simulation, a theoretical calculation, or the like, and stored in the control device 40.

[0025] FIG. 4 is a graph showing the relationship between the open circuit voltage OCV and the SOC. In FIG. 4, the relationship between the open circuit voltage OCV and the SOC is shown in a graph. Note that in FIG. 4, the relationship between the open circuit voltage OCV and the SOC is shown in a schematic manner and does not necessarily reflect the actual relationship. In FIG. 4, the open circuit voltage OCV after charging is shown by a solid line, and the open circuit voltage OCV after discharging is shown by a dashed line. As shown in FIG. 4, in the OCV-SOC conversion table, the open circuit voltage OCV is recorded in association with the SOC. In this embodiment, in the OCV-SOC conversion table shown in FIG. 4, the relationship between the open circuit voltage OCV and the SOC after charging is different from the relationship between the open circuit voltage OCV and the SOC after discharging. The relationship between the open circuit voltage OCV and the SOC used for estimating the SOC may be appropriately selected depending on whether the acquired current value is a current value acquired during charging or a current value acquired during discharging. The estimation of the SOC of the battery 1 is not limited to this form, and a conventionally known method such as an IV method in which an open circuit voltage V0 is obtained from a plot of a current value and a CCV may be used. The method of estimating the SOC may be determined according to the use form of the battery 1. For example, in the case of a battery (e.g., a stationary battery) in which the C rate or fluctuation of the current is small and the relationship between the SOC and the OCV is close to a straight line, the full charge capacity may be estimated from the relationship between the voltage value (the estimated value of the CCV or the OCV) and the current flow time. Similarly, in the case of a battery in which the C rate or fluctuation of the current is small and data in an SOC range in which the relationship between the SOC and the OCV is close to a straight line is used, the full charge capacity may be estimated from the relationship between the voltage value and the current flow time.

[0026] <Process B of extracting data D of battery 1> Step B of extracting data D of battery 1 includes determining whether or not the data acquired in step A satisfies a predetermined condition (step S4 in FIG. 2) and storing data D that satisfies the predetermined condition (step S5 in FIG. 2). For example, step B of extracting data D of battery 1 may include determining whether or not data acquired or processed over time in step A satisfies a predetermined condition at each time, and storing as data D all or a part of the data acquired or processed in step A at the time when it is determined that the data satisfies the predetermined condition.

[0027] In step S4, the first determination unit 44 (see FIG. 1) determines whether the data acquired by the acquisition unit 41 satisfies a predetermined condition. The predetermined condition is preferably set based on a condition that can improve the accuracy of estimating the SOC. As an example, a case where it is determined whether the condition is satisfied based on the acquired current value will be described.

[0028] In this embodiment, the predetermined condition is set based on the acquired current value and the time when the current value is acquired. The predetermined condition (hereinafter also referred to as "judgment condition") is set to the fact that the magnitude of the current acquired in the step A is equal to or less than a predetermined threshold value and continues for a predetermined time. Here, "the magnitude of the current" refers to the absolute value of the current value, and the absolute value of the current value during charging and the absolute value of the current value during discharging are used for the judgment. Although not particularly limited, the threshold value used for the judgment may be set based on the C rate. The threshold value may be set to, for example, a C rate of 0.1 or a C rate of 0.2. As described above, the acquired current value is associated with the time. The judgment condition of the time may be set to, for example, 10 seconds or more. The judgment condition of the time may be set to, for example, 30 seconds or less. Note that the threshold value of the current value and the judgment condition of the time may be appropriately set according to the configuration, the usage form, etc. of the battery 1, and are not limited to the above-mentioned range. From the viewpoint of increasing the amount of data D extracted in the step B, the current value may be set to be high and the time may be set to be short. From the viewpoint of increasing the accuracy of the data D extracted in the process B, the current value can be set low and the time can be set long.

[0029] Here, the judgment condition is set to whether or not a current of C rate 0.2 or less continued for 20 seconds. If it is judged that a current greater than C rate 0.2 flowed at least at any time from a certain time to a time 20 seconds before (NO), the first judgment unit 44 does not store data in the storage unit 53 and returns to step S2. Note that, as a measure against unavoidable noise, etc., the judgment condition may be set so that if a current exceeding a threshold value (C rate 0.2 in this embodiment) is detected only for an extremely short time (several samples, for example, two samples), it is not judged that a current greater than C rate 0.2 has flowed. If it is judged that a current of C rate 0.2 or less has flowed from a certain time to a time 20 seconds before (YES), the first judgment unit 44 stores data of the process A at that time (for example, a current value, a voltage value, a temperature value, a current integrated value, SOC, etc.) as data D (step S5 in FIG. 2). The data D is stored in the storage unit 53. Here, the storage unit 53 may be, for example, a volatile memory or a non-volatile memory. Once the data D is stored in the storage unit 53, the process proceeds to step S6.

[0030] The judgment condition in step S4 is not limited to one condition. For example, different judgment conditions may be set according to the timing of judgment. For example, from when the judgment condition is not satisfied to when it is satisfied and data D is stored for the first time, the judgment condition may be set to whether or not a current of C rate 0.2 or less continues for 10 seconds. If this judgment condition is satisfied and data D is stored for the first time, and the judgment condition continues to be satisfied, the judgment condition may be set to whether or not a current of C rate 0.2 or less continues for 5 seconds. However, if the judgment condition set to whether or not a current of C rate 0.2 or less continues for 10 seconds or 5 seconds is not satisfied even once, this judgment condition is reset, and the judgment condition may be set again to whether or not a current of C rate 0.2 or less continues for 10 seconds. There are cases where the detected data is not stable at the beginning of the current flow, etc. By setting different judgment conditions according to the timing of judgment, the acquired data D can be stabilized, and the reliability of the data D can be improved.

[0031] When a current flows through the battery 1, an error may occur in the open circuit voltage OCV estimated from the detected voltage value. Such an error may occur due to a voltage drop. The smaller the current flowing through the battery 1, the smaller the error due to the voltage drop. As described above, by using data D when the absolute value of the current is low, the accuracy of the open circuit voltage OCV is improved, and as a result, the accuracy of the SOC estimated based on the open circuit voltage OCV is improved. The accuracy of the estimated SOC may be improved in the estimation of the full charge capacity F in the step C by improving the accuracy of the estimated SOC.

[0032] In step S6, the second determination unit 45 determines whether the ignition switch is off. If the ignition switch is not off (NO), the process returns to step S2, and data acquisition and storage of data D that satisfies the predetermined condition are repeated. If the ignition switch is off (YES), data acquisition and extraction are completed, and the process proceeds to step S7.

[0033] In step S7, the third determination unit 46 determines whether the number of extracted data D (data D stored in the storage unit 53) is less than n. Here, n is an integer equal to or greater than 3. Although not particularly limited, n may be determined in advance from the viewpoint of statistically estimating the full charge capacity F, the amount of memory required for estimating the full charge capacity F, and the like. If the number of extracted data D is less than n (YES), the full charge capacity F of the battery 1 is not estimated, and the process ends. If the number of extracted data D is not less than n (the number of extracted data D is equal to or greater than n) (NO), the full charge capacity F of the battery 1 is estimated. In addition, an additional condition may be set as a determination condition for estimating the full charge capacity F or ending the process. For example, an additional condition may be set based on the maximum and minimum values ​​of the SOC of the stored data D. Even if the number of extracted data D is not less than n, if the difference between the maximum and minimum values ​​of the SOC of the stored data D is smaller than a predetermined threshold, the full charge capacity F of the battery 1 may not be estimated, and the process may end.

[0034] <Process C of estimating full charge capacity F of battery 1> In a process C of estimating the full charge capacity F of the battery 1, the full charge capacity F of the battery 1 to be measured is estimated based on the data D extracted in the process B (step S8).

[0035] In step S8, the second estimation unit 47 estimates the full charge capacity F of the battery 1 based on the current integrated value and the estimated SOC included in the data D. The second estimation unit 47 may statistically determine the full charge capacity F from the current integrated value and the SOC included in the extracted data D. The full charge capacity F may be determined by, for example, the least squares method. This can improve the accuracy of estimating the full charge capacity F.

[0036] 5 is a graph showing the relationship between the integrated current value of the extracted data D and the SOC. Here, the full charge capacity F is estimated based on the integrated current value and the SOC of the extracted data D. As shown in FIG. 5, the integrated current value and the SOC of the extracted data D are plotted in the graph. The full charge capacity F may be calculated by determining the slope of the graph when the horizontal axis is SOC (%) and the vertical axis is the integrated current value (Ah), and multiplying the determined slope by 100.

[0037] The full charge capacity F estimated in step S8 may be stored in the storage unit 53. The stored full charge capacity F may be referred to the next time the full charge capacity is estimated. The storage unit 53 may also store the previously estimated full charge capacity, etc.

[0038] According to the findings of the present inventor, the SOC is estimated based on data acquired at two timings when no current flows through the battery, and the full charge capacity F is estimated. For example, for a battery mounted on an electric vehicle (e.g., an electric vehicle (BEV), a plug-in hybrid vehicle (PHEV)), data is acquired at timings such as before and after driving, before and after charging and discharging at a charging and discharging spot, and while the electric vehicle is at rest, and the full charge capacity is estimated. Attempts have been made to improve the estimation accuracy of the full charge capacity by acquiring data at two timings where the difference in SOC is large and estimating the full charge capacity. However, for a battery mounted on an electric vehicle such as a commercial vehicle that has a long operating time and a short rest period between charging and discharging, there are cases where the rest time for estimating the SOC at two points is not sufficient. In this case, data is not acquired stably, and the estimation accuracy of the full charge capacity may decrease. In addition, when the battery is charged immediately after the electric vehicle is stopped, the difference in SOC between the two points becomes small, and the estimation accuracy of the full charge capacity may decrease. In addition, in a hybrid electric vehicle (HEV) in which the battery is repeatedly charged and discharged while the vehicle is running, the difference in SOC between the two points becomes small, and the accuracy of estimating the full charge capacity may decrease.

[0039] In contrast, in the above-described embodiment, the method for estimating the full charge capacity of a battery includes step A including acquiring battery data D including voltage, current, and temperature values ​​obtained over time from the battery 1 to be measured and processing the acquired data D, step B including extracting n or more pieces of data D that satisfy a predetermined condition, and step C including estimating the full charge capacity F of the battery 1 to be measured based on the data D extracted in step B, where n is an integer equal to or greater than 3.

[0040] In this full charge capacity estimation method, the full charge capacity F is estimated based on three or more data points D, so the accuracy of estimating the full charge capacity F is improved compared to estimating the full charge capacity F based on data between two points. In addition, data D that satisfies a predetermined condition (in the above-mentioned embodiment, a condition that can improve the estimation accuracy of the SOC) is extracted from the data obtained over time and used to estimate the full charge capacity F. The accuracy of estimating the full charge capacity F is improved by using the data D that satisfies the above-mentioned judgment condition and includes a relatively accurate SOC. In addition, data that does not satisfy the predetermined condition is not extracted. Therefore, the error in estimating the full charge capacity F is reduced compared to estimating the full charge capacity F by simply increasing the number of data. In addition, by preventing the amount of data from becoming too large, the memory used in the process of estimating the full charge capacity F can be kept low.

[0041] In addition, as described above, when estimating the full charge capacity F based on data between two points, if the difference in SOC between the two points is small, the estimation accuracy of the full charge capacity may decrease. FIG. 9 is a graph showing the relationship between SOC and current integrated value. In FIG. 9, the relationship between SOC and current integrated value is shown typically, and does not necessarily reflect the actual form. In FIG. 9, the possible SOC error is indicated by an arrow. Here, the possible SOC error is assumed to be constant and not dependent on SOC. In FIG. 9, the graph showing the maximum slope for each of the cases where the SOC difference is small (two-dot chain line in FIG. 9) and large (single-dot chain line in FIG. 9) is shown together with the graph showing the case where there is no error (solid line in FIG. 9). According to the findings of the present invention, when the SOC difference is small (ba), the slope of the graph is more likely to fluctuate than when the SOC difference is large (ca). As a result, the slope of the graph may increase the error of the estimated value of the full charge capacity. For example, in a hybrid vehicle in which the battery is repeatedly charged and discharged while the vehicle is running, the difference in SOC between two points is unlikely to become large when the vehicle is stopped or paused. However, in the above-described full charge capacity estimation method, since data D can be acquired while the vehicle is running, data D acquired over a relatively wide range of SOC while the vehicle is running can be used. As a result, the accuracy of estimating the full charge capacity F can be improved.

[0042] In step B of extracting data D of battery 1, if the data D extracted in step B is greater than n, the data D may be further narrowed down. For example, the data D may be further narrowed down to data D in descending order of priority based on a predetermined priority. The number of data D after narrowing down may be n, or may be a predetermined number equal to or greater than n. An embodiment including a process of further narrowing down the data D based on priority will be described below.

[0043] Fig. 6 is a flowchart showing a flow executed by the control device 40 of the full charge capacity estimation device 20. Fig. 6 shows a flowchart when a process different from the flow shown in Fig. 2 is executed. Note that steps S11 to S17 in Fig. 6 are similar to steps S1 to S7 in Fig. 2, respectively, and therefore detailed description will be omitted.

[0044] In step S17, similarly to step S7, the third determination unit 46 determines whether the number of extracted data D is less than n. If the number of extracted data D is less than n (YES), the full charge capacity Fr of the battery 1 is not estimated and the process ends. If the number of extracted data D is greater than n (NO), the process proceeds to step S18.

[0045] In step S18, the determination unit 48 determines the priority of the data D based on the predetermined priority. The data D is further narrowed down in the order of priority. The predetermined priority may be set based on a condition that can improve the accuracy of estimating the SOC. The priority may be determined based on the data D stored in the storage unit 53.

[0046] In this embodiment, the priority is set so that the priority is higher when the change in the open circuit voltage relative to the change in the estimated value of SOC is larger in the data D stored in the storage unit 53. Here, the priority is set based on the OCV-SOC conversion table shown in FIG. 4. As described above, the SOC is estimated based on the open circuit voltage OCV estimated from the voltage behavior model and the OCV-SOC conversion table. As shown in FIG. 4, the relationship between the open circuit voltage OCV and the SOC is not linear, and the slope of the graph varies depending on the value of SOC. For example, the slope of the graph tends to be larger on the high SOC side of the graph. The larger the slope of the graph, the smaller the error in the conversion from the open circuit voltage OCV to SOC. The smaller the slope of the graph, the larger the error in the conversion from the open circuit voltage OCV to SOC. By setting the priority so that the priority is higher when the change in the open circuit voltage OCV relative to the estimated value of SOC is larger, the error in the estimated value of SOC is reduced, and the full charge capacity Fr can be accurately estimated.

[0047] In the OCV-SOC conversion table, the table may be divided into a plurality of sections according to the SOC. For example, the sections may be divided every 1% to 5% of SOC. The slope of the graph may be calculated for each divided section. Priority may be determined such that the data including the SOC in a section with a steeper slope of the graph has a higher priority. In addition, each SOC (or each open circuit voltage OCV) in the OCV-SOC conversion table may be associated with a slope of the graph. The data D associated with the SOC with a steeper slope of the graph may have a higher priority.

[0048] The data D1 may also be extracted by a least squares method. The current integrated value and SOC of each data D are plotted on a graph, and a least squares line is drawn. The more distant the data D is from the least squares line, the lower the priority may be set. Data D with a low priority may be deleted so that a number of data D1 determined according to the memory of the control device 40 remains.

[0049] Based on the priority determined by the determination unit 48, a predetermined number of data D1 may be extracted from the data D extracted in the process B. The number of data D1 to be extracted may be a predetermined number, or may be determined as a ratio to the data D extracted in the process B. The number of data D1 is determined according to the memory of the control device 40 as described above, and is not particularly limited. The number of data D1 may be selected from a number of 3 or more, or from a number of 10 or more. The number of data D1 may be selected from a number of 1000 or less, or from a number of 500 or less. The number of data D1 may be set to, for example, 1 / 2 or less of the data D, or 1 / 10 or less. The number of data D1 may be set based on the memory capacity of the control device 40. When the data D1 with high priority is narrowed down in step S18, the process proceeds to step S19.

[0050] In the above embodiment, the data D extracted in the process B is narrowed down based on the priority, but the present invention is not limited to this. For example, when all the data D extracted in the process B have a priority higher than a predetermined threshold, all the data D may be used to estimate the full charge capacity Fr in the process C. For example, by using a large amount of data D with high priority, the estimation accuracy of the full charge capacity Fr in the process C may be improved.

[0051] In step S19, the full charge capacity Fr is estimated based on the data D1 narrowed down from the extracted data D (step C). In step S19, the full charge capacity Fr is estimated in the same manner as in step S8 (see FIG. 2) described above. Here, the full charge capacity Fr is statistically calculated from the current integrated value and SOC included in the data D1.

[0052] FIG. 7 is a graph showing the relationship between the current integrated value and SOC of the narrowed-down data D1. The data D1 is further narrowed down from the data D based on the priority. As shown in FIG. 7, the graph in which the current integrated value and SOC of the data D1 are plotted has smaller variations in data points than the graph in which the current integrated value and SOC of the data D are plotted. In this way, the data D1 with high priority is used to estimate the full charge capacity, so that the accuracy of the full charge capacity estimation can be improved. In addition, the memory used in the process of estimating the full charge capacity can be reduced by narrowing down the data D based on the priority.

[0053] In this embodiment, the full charge capacity estimation method further includes a step D of updating the full charge capacity by weighting the previously estimated full charge capacity Fp and the full charge capacity Fr estimated in the step C according to a predetermined condition. Here, the full charge capacity Fr is the full charge capacity Fr estimated in step S19 of the step C.

[0054] <Process D of weighting the full charge capacity Fp and the full charge capacity Fr> The process D of weighting the full charge capacity Fp and the full charge capacity Fr includes calculating a weighting coefficient W (step S20 in FIG. 6) and estimating the full charge capacity F using the weighting coefficient W (step S21 in FIG. 6).

[0055] In step S20, the second calculation unit 49 calculates the weighting coefficient W according to a predetermined condition. The second calculation unit 49 calculates the weighting coefficient W based on the narrowed-down data D1 (or the extracted data D). In this embodiment, the predetermined condition for the process D is set based on the acquisition time of the data D1 extracted in the process B, the temperature value, the estimated SOC value, and the number of data D1 extracted in the process B. In this embodiment, the weighting coefficient W is determined based on a coefficient W1 relating to the acquisition time of the data D1, a coefficient W2 relating to the temperature value of the battery 1, a coefficient W3 relating to the estimated SOC value of the battery 1, and a coefficient W4 relating to the number of data D1. Here, the weighting coefficient W is calculated using the following formula (3): W = W1 × W2 × W3 × W4 (3) The weighting coefficient W is calculated based on the above. Each of the coefficients W1 to W4 is set to be equal to or greater than 0 and equal to or less than 1. Therefore, the weighting coefficient W can be equal to or greater than 0 and equal to or less than 1. Each of the coefficients W1 to W4 is assigned a value according to the value of each parameter. Each of the coefficients W1 to W4 may be determined in the form of a table in which the coefficients correspond to the values ​​of each parameter. Each of the coefficients W1 to W4 will be described below.

[0056] <Coefficient W1 related to the acquisition time of data D1> The acquisition time of the data D1 may be, for example, the time taken to acquire the data D1 used to estimate the full charge capacity Fr. The data D acquired in the process A is acquired in association with the time. Therefore, the data D1 used in the process C also includes time information. In this embodiment, the time between the first acquired data D1 and the last acquired data D1 among the data D1 narrowed down from the data D is adopted as the acquisition time of the data D1. The longer the acquisition time of the data D1, the greater the influence on the current integrated value, and the shorter the acquisition time of the data D1, the smaller the influence on the current integrated value. The coefficient W1 may be set higher as the acquisition time of the data D1 is shorter, and lower as the acquisition time of the data D1 is longer.

[0057] <Coefficient W2 related to temperature value of battery 1> The temperature value of battery 1 can affect the estimation error when estimating SOC from the open circuit voltage OCV. The lower the temperature value of battery 1, the higher the internal resistances 62, 63b (see FIG. 3) of battery 1, and therefore the larger the estimation error of OCV. Accordingly, the larger the estimation error of SOC. Therefore, the lower the temperature value of battery 1, the larger the estimation error. The higher the temperature value of battery 1, the smaller the estimation error. Coefficient W2 can be set higher as the temperature value of battery 1 is higher, and lower as the temperature value of battery 1 is lower.

[0058] <Coefficient W3 for the estimated SOC of battery 1> The range of the estimated SOC of the battery 1 may affect the error in estimating the full charge capacity Fr. For example, when the full charge capacity Fr is estimated using data D1 with a wide SOC range, the effect of the error of each data D1 on the error in estimating the full charge capacity Fr is small. On the other hand, when the full charge capacity Fr is estimated using data D1 with a narrow SOC range, the effect of the error of each data D1 on the error in estimating the full charge capacity Fr is large. The coefficient W3 may be set according to the difference between the maximum and minimum values ​​of the estimated SOC in the data D1. The coefficient W3 may be set higher as the range of the estimated SOC (e.g., the difference between the maximum and minimum values) is wider, and lower as the range of the estimated SOC is narrower.

[0059] <Coefficient W4 for the number of data D1> The number of data D1 may affect the estimated value of the full charge capacity Fr. When estimating the full charge capacity Fr by the least squares method or the like, the smaller the number of data D1, the larger the estimation error, and the larger the number of data D1, the smaller the estimation error. The coefficient W4 may be set higher as the number of data D1 increases and lower as the number of data D1 decreases.

[0060] As described above, the coefficients W1 to W4 may be determined based on the acquisition time of the data D1, the temperature value, the estimated value of the SOC, and the number of the data D1, and the weighting coefficient W may be calculated by the above formula (3). As described for each of the coefficients W1 to W4, the more reliable the estimated value of the full charge capacity Fr is, the larger the value of the weighting coefficient W may be. However, the calculation of the weighting coefficient W is not limited to this form. The weighting coefficient W may be calculated, for example, by a multidimensional table corresponding to the number of parameters contributing to the weighting (4 in the above-mentioned embodiment). In the calculation of the weighting coefficient W based on the multidimensional table, when each parameter is input, one value of the weighting coefficient W may be output. In addition, the parameters for calculating the weighting coefficient W are not limited to the acquisition time of the data D1, the temperature value, the estimated value of the SOC, and the number of the data D1. It is preferable that at least one of these parameters is selected for the calculation of the weighting coefficient W. Also, other parameters may be included in addition to the acquisition time of the data D1, the temperature value, the estimated SOC value, and the number of data D1.

[0061] After the weighting coefficient W is calculated in step S20, the full charge capacity F is estimated in step S21.

[0062] In step S21, the third estimation unit 50 estimates the full charge capacity F by using the weighting coefficient W calculated in step S20. In this embodiment, the third estimation unit 50 estimates the full charge capacity F based on the full charge capacity Fr estimated in the process C, the full charge capacity Fp stored in the storage unit 53, and the weighting coefficient W. Here, the full charge capacity F is calculated using the following formula (4): F = W × Fr + (1 - W) × Fp (4) It is estimated based on.

[0063] As described above, the full charge capacity F is estimated. In this embodiment, the full charge capacity estimation method further includes a step D of weighting the previously estimated full charge capacity Fp and the full charge capacity Fr estimated in the step C in accordance with a predetermined condition. By using the previously estimated full charge capacity Fp in addition to the full charge capacity Fr estimated in the step C to estimate the full charge capacity F, the accuracy of the estimation of the full charge capacity F can be improved.

[0064] In the above-described embodiment, the weighting conditions are set based on the acquisition time of the data D1, the temperature value, the estimated value of the SOC, and the number of data D1. These parameters may affect the estimation accuracy of the full charge capacity Fr in the process C. In other words, these parameters may affect the reliability of the data D1 used when estimating the full charge capacity Fr in the process C. Here, the higher the reliability of the data D1 used when estimating the full charge capacity Fr in the process C, the larger the weighting coefficient W. In this case, the weight of the full charge capacity Fr estimated in the process C is increased. On the other hand, the lower the reliability of the data D1, the larger the weight of the previously acquired full charge capacity Fp is. The weighting conditions are set based on the acquisition time of the data D1, the temperature value, the estimated value of the SOC, and the number of data D1, which may affect the reliability of the data D1, and therefore the accuracy of the estimation of the full charge capacity F can be improved.

[0065] In the above-described embodiment, the case where the battery 1 is used as an in-vehicle battery has been described as an example of an embodiment in which the full charge capacity F is estimated when the external load is stopped. However, the present invention is not limited to this form, and the full charge capacity F may be estimated in a state in which the external load is not stopped. For example, the full charge capacity F may be estimated when a predetermined number of data D are extracted without determining whether the ignition switch is on or off in steps S6 and S16. The technology disclosed herein is also applicable to a battery 1 through which a current always flows. Examples of such a battery 1 include stationary batteries connected to a grid power source, a power generation device, electrical equipment, and the like. Hereinafter, a process for estimating the full charge capacity in a battery 1 used in a form in which a current always flows will be described.

[0066] Fig. 8 is a flowchart showing a flow executed by the control device 40 of the full charge capacity estimation device 20. Fig. 8 shows the flow of a method for estimating the full charge capacity F of the battery 1 as a stationary battery. In the following explanation, when the same processes as those executed in the flows in Figs. 2 and 6 are executed, detailed explanations will be omitted.

[0067] The process shown in FIG. 8 may be started at a predetermined timing. Although not particularly limited, the process may be started at a certain time for a certain period, such as once every few days, once a week, or once every few weeks. The process may also be started by the owner operating a terminal that manages the battery 1. In step S31, at least a part of the current integrated value and SOC calculated before the start of the process may be reset. For example, a certain number or a certain ratio of the old stored current integrated values ​​and SOC may be reset.

[0068] In steps S32 to S34, the same processes as in steps S2 to S4 in Fig. 2 are executed. In step S32, data D is acquired. In step S33, a current integration value and an estimated SOC value are obtained. In step S34, it is determined whether or not the data D satisfies a predetermined condition. In step S35, if the data D satisfies the predetermined condition, the data D is stored.

[0069] In step S36, the fourth determination unit 51 determines whether or not either of the conditions that the number of stored data D is equal to or greater than a predetermined number N and that X time has passed since step S1 is satisfied. If either of these conditions is satisfied (if the number of stored data D is equal to or greater than N or if X time has passed since step S1) (YES), the process proceeds to step S37. If X time has not passed and the number of stored data D is less than the predetermined number N (NO), the process returns to step S32, and data acquisition and storage of data D that satisfies the predetermined condition are repeated. Note that "N" is preferably determined in advance from the viewpoint of the number of data required for statistically estimating the full charge capacity F. "N" is set to a number equal to or greater than the above-mentioned "n". From the viewpoint of improving the estimation accuracy of the full charge capacity F, it is preferable that "N" is set to a number as large as possible within the constraints of the memory amount and calculation amount of the control device 40. However, "N" can be set so that the weight W1 described above does not become too small.

[0070] In step S37, the fifth determination unit 52 determines whether the number of stored data D is less than n. If the number of stored data D is less than n (YES), the full charge capacity F of the battery 1 is not estimated and the series of processes ends. In the next process, the current integrated value and SOC calculated in the series of processes are reset, or old data D may be reset (step S31). If the number of stored data D is not less than n (NO), proceed to step S38. If the number of stored data D is equal to or greater than n, the process of estimating the full charge capacity starts.

[0071] In steps S38 to S41, the same processes as in steps S18 to S41 in the flow of FIG. 6 are executed. In step S38, the priority of the data D is determined, and the data D is narrowed down. In step S39, the full charge capacity Fr is estimated by the above-mentioned method. In step S40, the weighting coefficient W is calculated according to a predetermined condition. In step S41, the full charge capacity F is estimated using the weighting coefficient W. The full charge capacity F is estimated based on the full charge capacity Fr estimated in the process C, the previously estimated full charge capacity Fp, and the weighting coefficient W. The estimated full charge capacity F is stored in the memory unit 53.

[0072] In this embodiment, the battery 1 is used in a form that allows current to flow through it. Therefore, after the full charge capacity F is estimated in step S41, and even if the process ends without estimating the full charge capacity F, current continues to flow through the battery 1. After the series of processes ends, the process is immediately restarted, and the process of estimating the full charge capacity can be restarted.

[0073] However, in a battery 1 used in a manner in which current can always flow, there is no downtime, so it is difficult to obtain data at two timings where the difference in SOC is large, such as before and after charging or before and after discharging, and estimate the full charge capacity. According to the technology disclosed herein, it is possible to estimate the full charge capacity even for a battery 1 used in a manner in which there is no downtime and current can always flow. In addition, the full charge capacities F and Fr are estimated based on highly reliable data (data D that satisfies a predetermined condition, and data D1 that has a predetermined high priority), so the accuracy of the estimation of the full charge capacities F and Fr is good.

[0074] The extraction of the data D and the narrowing down of the data D1 in the process B are not limited to the above-described embodiment.

[0075] In the above-described embodiment, the condition for extracting data D in step B is set based on whether or not the magnitude of the current value acquired in step A continues for a predetermined time period at or below a predetermined threshold (steps S4, S14, S34). However, the extraction of data D is not limited to this form, and different conditions may be adopted.

[0076] The predetermined conditions in steps S4, S14, and S34 may be set based on the estimated value of polarization of the battery 1, which is determined based on the data D acquired in the process A. For example, the conditions may be set based on whether or not the ratio of the estimated value of polarization (Vp+Vohm) to the maximum value of polarization (Vohm+Vpmax) is equal to or less than a predetermined value (e.g., 0.1 or less). The conditions may be set so that the data D is stored when the estimated value of polarization (Vp+Vohm) is equal to or less than the above value. Note that Vpmax is the maximum value of the voltage Vp applied to the CR parallel circuit 63 in FIG. 3 when the amount of stored electricity in the capacitor 63a is maximum, and can be acquired in advance. The larger the current flowing in the same direction through the battery 1, and the longer the time that the current flows in the same direction through the battery 1, the more the polarization of the battery 1 may progress. If the current flowing in the battery 1 continues to be small (for example, if the current flowing is close to 0 A for several seconds to several minutes), the polarization gradually decreases. The decrease in polarization differs depending on the model of the battery 1, etc. The control device 40 may store, for example, a table that allows the degree of polarization to be referenced as a numerical value from data D (e.g., current value and time). In step B, this table may be referenced and data D when polarization is small may be extracted. A threshold value for determining whether or not to extract data D may be set for the estimated polarization value. The table used here may be obtained in advance by testing, simulation, theoretical calculation, etc. depending on the model of the battery 1, and may be stored in the control device 40.

[0077] As described above, the open circuit voltage OCV estimated based on the formula (2) is used for the SOC of the battery 1. The smaller the estimated value of the polarization voltage (Vp+Vohm), the smaller the estimation error of the open circuit voltage OCV. For this reason, a threshold value for the estimated value of the polarization voltage (Vp+Vohm) may be set, and data D for which the estimated value of the polarization voltage (Vp+Vohm) is equal to or smaller than the threshold value may be stored. By extracting data D with a small estimation error of the open circuit voltage OCV, the estimation error of the full charge capacity F may be reduced.

[0078] The predetermined conditions in steps S4, S14, and S34 may be set based on the fluctuation range of the current value acquired in process A. The fluctuation range of the current value may be determined, for example, based on the difference between the maximum and minimum current values ​​included in data D acquired multiple times. The smaller the fluctuation range of the current value, the smaller the estimation error of the open circuit voltage OCV. In process B, a threshold value for the fluctuation range of the current value may be set, and data D whose fluctuation range of the current value is equal to or smaller than the threshold value may be stored. By extracting data D based on the fluctuation range of the current value as a condition, the estimation error of the open circuit voltage OCV may be reduced, and the estimation error of the full charge capacity F may be reduced.

[0079] The predetermined conditions in steps S4, S14, and S34 may be set based on the change in SOC determined based on the data acquired in step A. The change in SOC may be determined based on the difference between the SOC estimated based on the acquired data D and the SOC estimated based on the previously acquired data. Data D with a small change in SOC has a reduced effect on the estimation error of the full charge capacity F. For example, when the current value flowing through the battery 1 is small, the current balance becomes close to 0 and the change in SOC becomes small. In step B, a threshold value for the change in SOC may be set, and data D with a change in SOC equal to or less than the threshold value may be stored. By extracting data D based on the fluctuation range of the current value as a condition, the estimation error of the open circuit voltage OCV may be reduced, and the estimation error of the full charge capacity F may be reduced.

[0080] The predetermined conditions in steps S4, S14, and S34 may be set based on the variance of the current values ​​acquired multiple times. When the variance of the current values ​​is small, data D including the most recently acquired current value may be stored.

[0081] The predetermined conditions in steps S4, S14, and S34 may be set based on the change in the open circuit voltage OCV relative to the estimated value of the SOC. As described above, in the graph showing the relationship between the open circuit voltage OCV and the SOC (see FIG. 4), the greater the gradient of the graph, the smaller the error in converting the open circuit voltage OCV to the SOC. When the open circuit voltage OCV (or SOC) that belongs to the section in which the gradient of the graph is greater is estimated, data D may be stored.

[0082] In the above embodiment, the conditions for narrowing down the data D1 from the extracted data D in the process B are set based on the change in the open circuit voltage relative to the estimated value of the SOC (steps S18 and S38). However, the narrowing down of the data D1 is not limited to this form, and different conditions may be adopted.

[0083] The priority in steps S18 and S38 may be determined based on the time that has elapsed since the data D was extracted. For example, a condition for determining the priority may be set such that, when a certain time has elapsed since the data D was initially extracted, the priority of the data D after the certain time has elapsed is lowered. If a long time has elapsed since the data D was initially extracted, the effect of an error in the current sensor 32 may become large. This may result in a large error in the estimation of the SOC. Although not particularly limited, the elapsed time here may be set to about 30 minutes to 1 hour.

[0084] The priority in steps S18 and S38 may be determined based on the battery temperature value when data D is extracted. The temperature value of battery 1 may affect the estimation error when estimating SOC from the open circuit voltage OCV. The lower the temperature value of battery 1, the larger the estimation error. The higher the temperature value of battery 1, the smaller the estimation error. For example, the priority determination conditions may be set so that when the temperature values ​​included in data D vary widely, the priority of data D with a low temperature value is lowered.

[0085] As the condition for determining the priority, one of the above-mentioned conditions may be selected, or a plurality of the above-mentioned conditions may be combined to determine the priority.

[0086] The above-mentioned estimates of the open circuit voltage OCV, SOC, full charge capacity F, etc. may be appropriately corrected. For example, the equation (2) for estimating the open circuit voltage OCV may include a term for correcting voltage hysteresis. The magnitude of the hysteresis may vary depending on the SOC. Data including an SOC with large hysteresis may be processed so that its contribution to estimating the full charge capacity is reduced.

[0087] For data including an SOC with large hysteresis, the weighting coefficient W may be corrected to be smaller when calculating the weighting coefficient W. If the number of pieces of data D, D1 is large and the range of SOC included in the data D, D1 is wide but the integrated current value is small, the weighting coefficient W may be corrected to be larger when calculating the weighting coefficient W. At this time, the battery 1 is charged and discharged in a balanced manner, so the estimation error of the full charge capacity may be reduced.

[0088] When estimating SOC based on the open circuit voltage OCV and the current integrated value, the reliability of each data D may be calculated and weighted according to the reliability to estimate SOC. Although not particularly limited, data D may be processed so that the reliability is high when the current value is small, when the temperature value of battery 1 is high, when the slope of the graph of open circuit voltage OCV-SOC is large, etc. The reliability of the current value may be determined based on the current for about 10 to 300 seconds, rather than just an instantaneous current for 0.1 seconds or the like.

[0089] When estimating the full charge capacity Fr, a confidence interval of the data D and D1 may be obtained, and a weighting factor W may be determined according to the width of the confidence interval (the difference between the upper limit and the lower limit of the confidence interval). The weighting factor W may be set to be larger as the width of the confidence interval becomes smaller.

[0090] The technology disclosed herein has been described above in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate unless a particular problem occurs. Furthermore, this specification includes the disclosures described in the following sections.

[0091] Section 1: A step A includes acquiring battery data including a voltage value, a current value, and a temperature value obtained over time from a battery to be measured, and processing the acquired data; A step B of extracting n or more pieces of data that satisfy a predetermined condition from at least one of the data acquired in the step A and the data obtained by the processing in the step A; A step C of estimating a full charge capacity of the battery to be measured based on the data extracted in the step B. Including, where n is an integer equal to or greater than 3. A method for estimating the full charge capacity of a battery.

[0092] Section 2: Item 2. The method for estimating a full charge capacity of a battery according to item 1, wherein the predetermined condition of step B is that the magnitude of the current acquired in step A remains below a predetermined threshold for a predetermined period of time.

[0093] Section 3: Item 3. The method for estimating a full charge capacity of a battery according to item 1 or 2, wherein in the step B, when the data extracted in the step B is greater than n, the data extracted in the step B is further narrowed down in order of priority based on a predetermined priority.

[0094] Section 4: The step A includes processing the acquired data based on a predetermined battery voltage behavior model to obtain an open circuit voltage and an estimated value of SOC; 4. The method for estimating a full charge capacity of a battery according to item 3, wherein the priority is determined such that the priority is higher when the change in the open circuit voltage relative to the change in the estimated SOC value is larger.

[0095] Section 5: The previously estimated full charge capacity is stored. The method for estimating a full charge capacity of a battery according to any one of items 1 to 4, further comprising a step D of weighting the previously estimated full charge capacity and the full charge capacity estimated in the step C according to a predetermined condition, to update the full charge capacity.

[0096] Item 6: the predetermined condition of the step D is set based on at least one of an acquisition time of the data extracted in the step B, the temperature value, the estimated value of SOC, and the number of data extracted in the step B; Item 6. The method for estimating a full charge capacity of a battery according to item 5, wherein the estimated value of the SOC is estimated based on the data acquired in step A and a predetermined battery voltage behavior model.

[0097] Section 7: The step A comprises: integrating the current value and calculating an integrated current value up to each time point of data of the battery obtained over time; obtaining an estimate of SOC based on data of the battery and a predetermined voltage behavior model; 7. The method for estimating a full charge capacity of a battery according to any one of claims 1 to 6,

[0098] Section 8: 8. The method for estimating a full charge capacity of a battery according to item 7, wherein the full charge capacity of the battery to be measured is estimated based on the integrated current value and the estimated SOC value.

[0099] Section 9: Item 2. The method for estimating a full charge capacity of a battery according to item 1, wherein the predetermined condition of step B is determined based on an estimated value of polarization of the battery obtained by processing the data acquired in step A.

[0100] Section 10: 2. The method for estimating a full charge capacity of a battery according to claim 1, wherein the predetermined condition in the step B is determined based on a fluctuation range of the current value acquired in the step A.

[0101] Section 11: Item 2. The method for estimating a full charge capacity of a battery according to item 1, wherein the predetermined condition in step B is determined based on a change in SOC obtained by processing the data acquired in step A.

[0102] Section 12: A sensor; Control device and Equipped with The sensor includes: A voltage sensor; A current sensor; Temperature sensor and Equipped with The control device includes: A process including acquiring data over time about a battery to be measured, the data including a voltage value, a current value, and a temperature value, and processing the acquired data; A process of extracting n or more pieces of data satisfying a predetermined condition from at least one of the acquired data and the data obtained by the process in step A, where n is an integer of 3 or more. A process of estimating the full charge capacity of the battery to be measured based on the extracted data. configured to run, Full charge capacity estimation device.

[0103] Section 13: The full charge capacity estimation device according to item 12, wherein the control device is configured to execute a process of further narrowing down the extracted data in descending order of priority based on a predetermined priority when the extracted data is greater than n.

[0104] Section 14: The control device stores a previously estimated full charge capacity, Item 14. The full charge capacity estimation device according to item 12 or 13, wherein the control device is configured to execute a process of weighting the previously estimated full charge capacity and the full charge capacity estimated based on the extracted data in accordance with a predetermined condition. [Explanation of symbols]

[0105] 1 battery 20 Full charge capacity estimation device 30 Sensors 31 Voltage Sensor 32 Current Sensor 33 Temperature Sensor 40 Control device 41 Acquisition Department 42 First Calculation Section 43 1st estimation part 44 1st Judgment Section 45 Second Judgment Section 46 Third Judgment Section 47 Second estimation part 48 Decision Section 49 Second Calculation Section 50 Third estimation part 51 4th Judgment Section 52 5th Judgment Section 53 Memory section 60 Voltage Behavior Model 61 Voltage Source 62 Internal Resistance 63 CR parallel circuit 63a Capacitor 63b Internal resistance 70 Control device 100 Battery System D, D1 data F,Fr Full charge capacity W weighting factor

Claims

1. A step A includes acquiring battery data including a voltage value, a current value, and a temperature value obtained over time from a battery to be measured, and processing the acquired data; A step B of extracting n or more pieces of data satisfying a predetermined condition from at least one of the data acquired in the step A and the data obtained by the processing in the step A; A step C of estimating a full charge capacity of the battery to be measured based on the data extracted in the step B; Including, Here, n is an integer of 3 or more. A method for estimating the full charge capacity of a battery.

2. 2. The method for estimating a full charge capacity of a battery according to claim 1, wherein the predetermined condition of step B is that the magnitude of the current acquired in step A remains below a predetermined threshold for a predetermined period of time.

3. 3. The method for estimating a full charge capacity of a battery according to claim 1, wherein, in step B, when the data extracted in step B is greater than n, the data extracted in step B is further narrowed down in order of priority based on a predetermined priority.

4. The step A includes processing the acquired data based on a predetermined battery voltage behavior model to obtain an open circuit voltage and an estimated value of SOC; 4. The method of estimating a full charge capacity of a battery according to claim 3, wherein the priority is determined such that the priority is higher when the change in the open circuit voltage relative to the change in the estimated value of SOC is greater.

5. The previously estimated full charge capacity is stored.

3. The method for estimating a full charge capacity of a battery according to claim 1 or 2, further comprising a step D of weighting the previously estimated full charge capacity and the full charge capacity estimated in the step C according to a predetermined condition, and updating the full charge capacity.

6. the predetermined condition of the step D is set based on at least one of an acquisition time of the data extracted in the step B, the temperature value, the estimated value of SOC, and the number of data extracted in the step B; 6. The method for estimating a full charge capacity of a battery according to claim 5, wherein the estimated value of SOC is estimated based on the data acquired in step A and a predetermined battery voltage behavior model.

7. The step A comprises: integrating the current value and calculating an integrated current value up to each time point of data of the battery obtained over time; obtaining an estimate of SOC based on data of the battery and a predetermined voltage behavior model; 3. The method for estimating a full charge capacity of a battery according to claim 1 or 2, comprising:

8. 8. The method for estimating a full charge capacity of a battery according to claim 7, wherein the full charge capacity of the battery to be measured is estimated based on the integrated current value and the estimated value of SOC.

9. 2. The method for estimating a full charge capacity of a battery according to claim 1, wherein the predetermined condition of step B is determined based on an estimated value of polarization of the battery obtained by processing the data acquired in step A.

10. 2. The method of estimating a full charge capacity of a battery according to claim 1, wherein the predetermined condition in the step B is determined based on a fluctuation range of the current value acquired in the step A.

11. 2. The method for estimating a full charge capacity of a battery according to claim 1, wherein the predetermined condition in step B is determined based on a change in SOC obtained by processing the data acquired in step A.

12. A sensor; Control device and Equipped with The sensor includes: A voltage sensor; A current sensor; Temperature sensor and Equipped with The control device includes: A process including acquiring data over time about a battery to be measured, the data including a voltage value, a current value, and a temperature value, and processing the acquired data; A process of extracting n or more pieces of data that satisfy a predetermined condition from at least one of the acquired data and the data obtained by the process, where n is an integer of 3 or more; A process of estimating the full charge capacity of the battery to be measured based on the extracted data. configured to run, Full charge capacity estimation device.

13. The full charge capacity estimation device of claim 12, wherein the control device is configured to, when the extracted data is greater than n, execute a process of further narrowing down the extracted data in order of priority based on a predetermined priority.

14. The control device stores a previously estimated full charge capacity, 14. The full charge capacity estimation device according to claim 12 or 13, wherein the control device is configured to execute a process of weighting the previously estimated full charge capacity and the full charge capacity estimated based on the extracted data in accordance with predetermined conditions.

Images