Battery full charge capacity estimation method, battery full charge capacity estimation device, and battery full charge capacity estimation program

Abstract

To estimate the full charge capacity of a battery with relatively high accuracy regardless of the degree of change in the state of charge.SOLUTION: In a step of estimating the full charge capacity of a battery 1, SOC1 and SOC2 are acquired on the basis of voltages V1 and V2 when the battery 1 is stable. The amount of change ΔSOC is acquired from SOC1 and SOC2. A current integrated value ΣA1 during a change of SOC from SOC1 to SOC2 is also acquired. An estimation unit 46 calculates an estimated value Hx from ΣA1 and ΔSOC when |ΔSOC| is equal to or more than a first threshold. When a predetermined condition is satisfied, the estimation unit 46 changes the first threshold to a second threshold. The second threshold is a threshold lower than the first threshold.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2002-243813 discloses a battery capacity degradation calculation device that includes a state-of-charge calculation unit that calculates changes in the state of charge of a secondary battery and a battery capacity calculation unit that calculates the battery capacity of the secondary battery in a degraded state. The degraded battery capacity is calculated from an integrated discharge current value during discharge and changes in the state of charge. The change in the state of charge is calculated from the correlation between the open-circuit voltage and the state of charge and the open-circuit voltage during discharge. Here, the correlation between the open-circuit voltage and the state of charge does not depend on the degraded state of the secondary battery. Therefore, if the correlation is known, it is possible to determine changes in the state of charge of the secondary battery and calculate the degraded battery capacity without, for example, preparing a table of internal resistance degradation of the secondary battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-243813 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, Patent Document 1 states that in order to improve the calculation accuracy of the deteriorated battery capacity, it is advisable to calculate the deteriorated battery capacity when the change in the state of charge is relatively large.

[0005] The inventors of the present invention wish to estimate the full charge capacity of a battery with relatively high accuracy, regardless of the magnitude of changes in the state of charge. [Means for solving the problem]

[0006] The method for estimating the full charge capacity of a battery disclosed herein is a method for estimating capacity degradation of a battery managed by a BMS (battery management system) mounted on an electric vehicle, and includes the steps of acquiring SOC1, which is an SOC obtained based on a voltage V1 that is the OCV of the battery; acquiring SOC2, which is an SOC obtained based on a voltage V2 that is the OCV of the battery at a point in time after the SOC of the battery is SOC1; acquiring a change ΔSOC between the SOC1 and the SOC2; acquiring a current integrated value ΣA1 of the battery until the SOC changes from SOC1 to SOC2; and, when |ΔSOC| is equal to or greater than a predetermined first threshold, acquiring an estimated value Hx of the full charge capacity of the battery based on equation (1). Formula (1): Hx = (ΣA1 / ΔSOC) × 100 Here, in the step of acquiring the estimated value Hx of the full charge capacity, if a predetermined condition is satisfied, the first threshold value is set to a second threshold value that is lower than the first threshold value.

[0007] According to this method for estimating the full charge capacity of a battery, the full charge capacity of the battery can be estimated with relatively high accuracy, regardless of the magnitude of changes in the state of charge. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a battery system 100. As shown in FIG. [Figure 2] FIG. 2 is a graph showing an example of changes in SOC in an electric vehicle equipped with the battery system 100. In FIG. [Figure 3] FIG. 3 is a flowchart for estimating the full charge capacity of the battery 1 according to the first embodiment. [Figure 4] FIG. 4 is a graph showing the relationship between the open circuit voltage OCV and the SOC. [Figure 5] FIG. 5 is a graph showing the relationship between the number of times that |ΔSOC| is determined to be lower than the threshold Tx and the threshold Tx. [Figure 6]FIG. 6 is a flowchart for estimating the full charge capacity of the battery 1 according to the second embodiment. [Figure 7] FIG. 7 is a flowchart for estimating the full charge capacity of the battery 1 according to the third embodiment. [Figure 8] FIG. 8 is a flowchart for estimating the full charge capacity of the battery 1 according to the fourth embodiment. [Figure 9] FIG. 9 is a diagram showing a capacity deterioration model DM of the battery 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, each embodiment of the technology disclosed herein will be described with reference to the drawings. It goes without saying that the embodiments described herein are not intended to particularly limit the present invention. Each drawing is a schematic illustration and does not necessarily reflect the actual product. Furthermore, the same reference numerals are appropriately used for components and parts that perform the same function, and redundant explanations will be omitted where appropriate.

[0010] First Embodiment <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 control unit 20. The battery 1 is connected to an external load (not shown). The control unit 20 manages the charging and discharging of the battery 1. In other words, the control unit 20 is an example of a BMS (Battary Management System) according to the present invention. The battery system 100 is, for example, an on-board system for an electric vehicle (battery EV).

[0011] In this specification, the term "battery" refers to an electricity storage device capable of extracting electrical energy. Batteries include secondary batteries 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, such as lithium-ion secondary batteries. The manner in which the battery is used is not particularly limited. The battery includes a battery pack in which a plurality of batteries (single cells) are electrically connected to one another. In this embodiment, the battery is, for example, a so-called on-board battery that serves as a power source for an electric vehicle. When the battery is used as an on-board battery, the battery is appropriately connected to a charging / discharging device and charged.

[0012] The full charge capacity of the battery 1 decreases over time as the battery 1 is charged and discharged. The full charge capacity is the battery capacity of the battery 1 that is fully discharged after being charged to a maximum charge capacity, that is, a state of charge (SOC) of 100%.

[0013] The control unit 20 includes a sensor 30 and a control device 40. The sensor 30 includes a voltage sensor 31, a temperature sensor 32, and a current sensor 33. The control device 40 includes a memory unit 41, a first state-of-charge acquisition unit 42, a second state-of-charge acquisition unit 43, a change amount acquisition unit 44, a current integrated value acquisition unit 45, an estimation unit 46, a determination unit 47, a counting unit 48, a count determination unit 49, an unexecuted time measurement unit 50, an unexecuted time acquisition unit 51, a time determination unit 52, a mileage measurement unit 53, a mileage acquisition unit 54, a distance determination unit 55, an estimated capacity acquisition unit 56, and an estimated value determination unit 57. 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 according to, for example, a predetermined program. Each function of the computer is processed by the computer's arithmetic unit (also called a processor, CPU (Central Processing Unit), or MPU (Micro-Processing Unit)), storage device (memory, hard disk, etc.), and software working together. In this embodiment, the control device 40 is realized by an ECU. A full charge capacity estimation program 40a is installed in the control device 40. The full charge capacity estimation program 40a is a program configured to realize each section 41 to 57 of the control device 40. The control device 40 is configured to be able to communicate with the sensor 30.

[0014] Although not shown in the figures, the control device 40 may be one in which multiple control devices work together. For example, if the control device 40 is connected to an external computer via a LAN cable, the Internet, or the like so as to be able to communicate data with the external computer, the processing of the control device 40 may be performed in cooperation with such an external computer. For example, the information or part of the information stored in the control device 40 may be stored in an external computer, or the processing or part of the processing performed by the control device 40 may be performed by an external computer.

[0015] FIG. 2 is a graph GP showing an example of changes in SOC in an electric vehicle equipped with battery system 100. The horizontal axis of graph GP represents time, and the vertical axis of graph GP represents the SOC of battery 1. In graph GP, the region defined by times 0 to t1 is designated area A1. Similarly, in graph GP, the regions defined by times t1 to t2, t2 to t3, and the region from time t3 onward are designated areas A2, A3, and A4, respectively. Area A1 is the region where the ignition (hereinafter simply referred to as "ignition") of the electric vehicle equipped with battery system 100 is OFF and the SOC is SOC1. Area A2 is the state where the ignition is ON after area A1. For example, the electric vehicle is running for a time corresponding to area A2. When the electric vehicle is running, battery 1 (see FIG. 1) discharges and the SOC decreases. However, the SOC may increase when the electric vehicle is running. For example, in the case of an HEV equipped with an engine, the SOC after driving may be higher than the SOC before driving. Area A3 is the area where the ignition is OFF and the SOC is SOC2. SOC2 is a state where the SOC is more discharged than SOC1. Area A4 is the area where the ignition is ON at a time later than area A3.

[0016] The voltage sensor 31 of the sensor 30 shown in FIG. 1 is a sensor that detects the voltage value of the battery 1. The voltage sensor 31 detects the voltage value of the battery 1, for example, as an analog signal. The detected analog signal is converted to a digital signal by an A / D converter (not shown) and output to the memory unit 41 of the control device 40. The temperature sensor 32 and current sensor 33 of the sensor 30 also detect the temperature and current value of the battery 1, respectively, similar to the voltage sensor 31. The detected temperature and current values ​​are transmitted to the memory unit 41. Therefore, the memory unit 41 of the control device 40 stores the voltage value, temperature value, and current value. The sensor 30 detects each value whether the ignition is on or off. The voltage sensor 31, temperature sensor 32, and current sensor 33 detect the voltage value, temperature value, and current value, respectively, at predetermined intervals. The intervals at which the voltage sensor 31, temperature sensor 32, and current sensor 33 perform detection are not particularly limited, but are, for example, approximately 0.001 to 1 second.

[0017] A method for estimating the full charge capacity of the battery 1 by the control unit 20 will be described below, along with the configuration of the control unit 20. Fig. 3 is a flowchart for estimating the full charge capacity of the battery 1 according to the first embodiment. The flow shown in Fig. 3 is performed at time t3 shown in Fig. 2 (when the ignition is turned on at the boundary between area A3 and area A4). However, the timing at which the flow starts is not limited to this.

[0018] Step S101 shown in FIG. 3 is a process of acquiring SOC1, which is an SOC obtained based on voltage V1, which is the OCV (Open Circuit Voltage) of battery 1. Step S101 can be implemented by the first state-of-charge acquisition unit 42 (see FIG. 1) of the control device 40. It is preferable that voltage V1 is the OCV when battery 1 is stable. Here, "stable battery 1" refers to a state in which battery 1 is not being charged or discharged and the OCV does not change. In this embodiment, this refers to, for example, a state in which the ignition is turned off. However, "no change in OCV of battery 1" does not only refer to a state in which the OCV value does not change at all, but also includes slight fluctuations in OCV due to, for example, temperature changes, internal reactions of battery 1, or measurement errors of sensor 30. In step S101, the OCV at time t1 (see FIG. 2) is acquired as voltage V1. In this embodiment, the ignition has been turned off for a period of time before time t1, so the voltage at time t1 can be considered the OCV. First, the first state-of-charge obtaining unit 42 obtains the voltage value, temperature value, and current value detected by the voltage sensor 31, temperature sensor 32, and current sensor 33, respectively, from the storage unit 41. The first state-of-charge obtaining unit 42 obtains each piece of data at time t1. Note that if the voltage value detected by the voltage sensor 31 is a closed circuit voltage, the OCV may be estimated using the closed circuit voltage or a conventionally known voltage behavior model.

[0019] The SOC1 of the battery 1 is estimated based on the estimated voltage V1. In this embodiment, the SOC1 of the battery 1 is estimated using an OCV-SOC conversion table (see FIG. 4) that is stored in advance in the control device 40. The OCV-SOC conversion table may be obtained in advance by testing, simulation, theoretical calculation, or the like, and may be stored in the control device 40.

[0020] 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 graphically. Note that FIG. 4 shows the relationship between the open-circuit voltage OCV and the SOC only 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 the OCV-SOC conversion table shown in FIG. 4, the relationship between the open-circuit voltage OCV and the SOC after charging differs 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 to estimate the SOC may be appropriately selected depending on whether the current value acquired during charging or discharging is a current value acquired during discharging. Note that the estimation of the SOC of the battery 1 is not limited to this form, and a conventionally known method, such as the IV method, in which the open-circuit voltage is determined from a plot of the current value and the CCV, may also be used. The method for estimating the SOC may be determined depending on the usage pattern of the battery 1. In this embodiment, the SOC1 value estimated using the OCV-SOC conversion table and the voltage V1 is assumed to be 80%. However, the SOC1 value is not limited to this.

[0021] Step S102 shown in FIG. 3 is a process of acquiring SOC2, which is an SOC obtained based on voltage V2, which is the OCV of battery 1, at a time later than the time when the SOC of battery 1 is SOC1. Step S102 can be implemented by second state-of-charge acquisition unit 43 (see FIG. 1) of control device 40. Note that, like voltage V1, voltage V2 is preferably a voltage when battery 1 is stable. In this embodiment, in step S102, OCV at time t3 (see FIG. 2) is acquired as voltage V2. Like first state-of-charge acquisition unit 42, second state-of-charge acquisition unit 43 acquires voltage values, temperature values, and current values ​​from storage unit 41. Second state-of-charge acquisition unit 43 acquires voltage values, temperature values, and current values ​​at time t3. In this embodiment, the ignition remains in an OFF state between times t2 and t3. Therefore, the voltage value at time t3 can be regarded as OCV. Therefore, the voltage value at time t3 is regarded as voltage V2. If the voltage value detected by the voltage sensor 31 is a closed circuit voltage, the OCV may be estimated using the closed circuit voltage or a conventionally known voltage behavior model. Similar to the first state of charge acquisition unit 42, the second state of charge acquisition unit 43 acquires the SOC2 using an OCV-SOC conversion table (see FIG. 4) and the voltage V2. In this embodiment, the value of SOC2 is set to 40%. However, the value of SOC2 is not limited to this.

[0022] Step S103 shown in FIG. 3 is a process of acquiring the change amount ΔSOC between SOC1 and SOC2. Step S103 can be implemented by the change amount acquisition unit 44 (see FIG. 1) of the control device 40. The change amount acquisition unit 44 calculates the difference between SOC1 acquired by the first state of charge acquisition unit 42 and SOC2 acquired by the second state of charge acquisition unit 43 to acquire the change amount ΔSOC. Here, the change amount ΔSOC is calculated as ΔSOC=SOC2-SOC1. In this embodiment, as described above, the value of SOC1 is 80% and the value of SOC2 is 40%, so the value of the change amount ΔSOC is −40%. Therefore, in this embodiment, the change amount ΔSOC is < 0. However, the change amount ΔSOC is not limited to ΔSOC < 0. For example, if charging occurs using regenerative energy or the like when the ignition is on, ΔSOC may be ΔSOC≧0.

[0023] Step S104 is a process of acquiring an integrated current value ΣA1 of the battery 1 until the SOC changes from SOC1 to SOC2. Step S104 can be implemented by the integrated current value acquiring unit 45 (see FIG. 1). The integrated current value ΣA1 is an integrated current value from time t1 to t2. Here, the integrated current value ΣA1 is calculated as the integrated current value accumulated up to the previous time + Δt × current value. Δt is a predetermined time interval. As described above, the current sensor 33 (see FIG. 1) detects the current value at predetermined intervals. Therefore, Δt is the time interval between two consecutive current value data in the data stored in the storage unit 41. The integrated current value acquiring unit 45 calculates the integrated current value ΣA1 by integrating the current value data for the time t1 to t2 contained in the storage unit 41. In this embodiment, the SOC value decreases between time t1 and t2 as shown in FIG. 2. That is, in region A2, battery 1 (see FIG. 1) is discharging. Here, the current value during discharging is expressed as a negative value. Therefore, here, ΣA1<0. Note that when battery 1 is charged and the SOC value increases, ΣA1>0 may be satisfied.

[0024] Step S105 is a step of determining whether the absolute value |ΔSOC| of the change amount ΔSOC is lower than a predetermined threshold value Tx. In step S105, the threshold value Tx is preset to a first threshold value T1. The threshold value Tx is a threshold value for determining whether to acquire an estimated value Hx of the battery 1, which will be described later. The threshold value Tx is preset to the first threshold value T1 by the estimation unit 46 (see FIG. 1). Therefore, in step S105, it is determined whether |ΔSOC| is lower than the first threshold value T1. The determination in step S105 can be performed by the determination unit 47 (see FIG. 1) of the control device 40. In this embodiment, the value of |ΔSOC| is 40% of the ΔSOC acquired by the change amount acquisition unit 44 in step S103. The determination unit 47 determines whether |ΔSOC| is lower than the first threshold value T1. If it is determined that |ΔSOC| is lower than the first threshold value T1, the process proceeds to step S106. When it is determined that |ΔSOC| is not lower than the first threshold T1, that is, |ΔSOC| is equal to or greater than the first threshold, the process proceeds to step S111.

[0025] Here, the counting unit 48 (see FIG. 1) of the control device 40 counts the number of times that |ΔSOC| is determined to be lower than the threshold value Tx. The counting unit 48 has a counter (not shown). The counter stores the number of times CT that |ΔSOC| is determined to be lower than the threshold value Tx (hereinafter referred to as the "determination number CT").

[0026] In step S106, it is determined whether |ΔSOC| has been lower than a predetermined first threshold T1 for a predetermined number of consecutive times. Step S106 can be implemented by the count determination unit 49 (see FIG. 1) of the control device 40. In this embodiment, the count determination unit 49 determines whether the determination count CT stored in the counter 48 is equal to or greater than a first threshold N1. As will be described in detail later, in this embodiment, if it is determined that |ΔSOC| is equal to or greater than the first threshold, the determination count CT is set to 0 in step S112 (described later). Therefore, the determination count CT is the number of consecutive times that |ΔSOC| has been lower than the first threshold T1. In this embodiment, for example, the first count N1 is 30 times. However, the value of the first count N1 is not particularly limited. In step S106, if it is determined that the determination count CT has reached the first count N1, the estimation unit 46 changes the threshold Tx from the first threshold T1 to a second threshold T2. The second threshold T2 is a value lower than the first threshold T1.

[0027] 5 is a graph showing the relationship between the number of determinations CT and the threshold value Tx. In this embodiment, as shown in FIG. 5, when the number of determinations CT (horizontal axis) is less than the first number N1 (30 times), the threshold value Tx is set to the first threshold value T1. When the number of determinations CT is equal to or greater than the first number N1 (30 times) and less than a second number N2 (described later), the estimation unit 46 (see FIG. 1) sets the threshold value Tx to the second threshold value T2. When it is determined in step S106 shown in FIG. 3 that the number of determinations CT is equal to or greater than the first number N1, the process proceeds to step S107. When it is determined that the number of determinations CT is less than the first number N1, the process proceeds to step S110.

[0028] Step S107 is a step of determining whether |ΔSOC| is lower than a predetermined threshold value Tx. As described above, in step S106, the threshold value Tx is set to the second threshold value T2. Therefore, in step S107, it is determined whether |ΔSOC| is lower than the predetermined second threshold value T2. The determination in step S107 can be performed by the determination unit 47 (see FIG. 1). In step S107, the determination unit 47 determines whether |ΔSOC| is lower than the second threshold value T2. If it is determined in step S107 that |ΔSOC| is lower than the second threshold value T2, the process proceeds to step S108. If it is determined that the value of |ΔSOC| is not lower than the second threshold value T2, that is, if it is determined that the value of |ΔSOC| is equal to or greater than the second threshold value T2, the process proceeds to step S111.

[0029] In step S108, it is determined whether ΔSOC has been lower than a predetermined second threshold T2 for a predetermined number of consecutive times. Step S108 can be implemented by the count determination unit 49 (see FIG. 1). In this embodiment, the count determination unit 49 determines whether the determination count CT stored in the counting unit 48 is equal to or greater than a second count N2. In this embodiment, for example, the second count N2 is 60. As described above, until the determination count CT reaches the first count N1, the threshold Tx is set to the first threshold T1, and the count determination unit 49 performs determination. Also, as described above, if it is determined in step S105 that |ΔSOC| is equal to or greater than the first threshold T1, the determination count CT is set to 0 in step S112, which will be described later. Therefore, when the number of determinations CT reaches the second number of times N2=60, it means that |ΔSOC| has been determined to be lower than the second threshold value T2 for a number of consecutive times equal to the difference between the second number of times N2 and the first number of times N1 (60 times - 30 times = 30 times). The number of determinations determination unit 49 determines whether the value of the number of determinations CT is equal to or greater than the second number of times N2. If it is determined in step S108 that the number of determinations CT is equal to or greater than the second number of times N2, the estimation unit 46 sets the threshold value Tx to a third threshold value T3. As shown in FIG. 5, the third threshold value T3 is a value lower than the second threshold value T2. After the threshold value Tx is set to the third threshold value T3, the process proceeds to step S109 shown in FIG. 3. If it is determined that the number of determinations CT is less than the second number of times N2, the process proceeds to step S110.

[0030] Step S109 is a step of determining whether |ΔSOC| is lower than a predetermined threshold value Tx. As described above, in step S108, the threshold value Tx is set to the third threshold value T3. Step S109 is a step of determining whether |ΔSOC| is lower than the predetermined third threshold value T3. Step S109 can be implemented by the determination unit 47. The determination unit 47 determines whether |ΔSOC| is lower than the third threshold value T3. If it is determined in step S109 that |ΔSOC| is lower than the third threshold value T3, the process proceeds to step S110. If it is determined that the value of |ΔSOC| is not lower than the third threshold value T3, that is, the value of |ΔSOC| is equal to or greater than the third threshold value T3, the process proceeds to step S111.

[0031] Step S110 is a step of incrementing the value of the determination count CT. If it is determined in step S106 that |ΔSOC| is lower than the first threshold T1, if it is determined in step S108 that |ΔSOC| is lower than the second threshold T2, or if it is determined in step S109 that |ΔSOC| is lower than the third threshold T3, the counting unit 48 increments the determination count CT stored in the counter by 1 and stores the count. Once step S110 is executed, the flow ends.

[0032] Step S111 is a step of determining whether |ΔSOC| is equal to or greater than a predetermined first threshold T1, a predetermined second threshold T2, or a predetermined third threshold T3. Formula (1): Hx = (ΣA1 / ΔSOC) × 100 (1) This is a step of acquiring an estimated value Hx of the full charge capacity of the battery 1 based on |ΔSOC|. Step S111 can be implemented by the estimation unit 46 (see FIG. 1). The process proceeds from step S106 to step S111 when |ΔSOC| is equal to or greater than the first threshold T1. The process proceeds from step S108 to step S111 when |ΔSOC| is equal to or greater than the second threshold T2. The process proceeds from step S109 to step S111 when |ΔSOC| is equal to or greater than the third threshold T3. In this embodiment, since ΣA1<0 and ΔSOC<0, the estimated value Hx is a positive value. Note that, for example, if the battery 1 is charged between times t1 and t2, ΣA1>0 and ΔSOC>0, and therefore the estimated value Hx>0 in this case as well.

[0033] Step S112 is a process of initializing the number of determinations CT. In step S112, the counting unit 48 initializes the value of the number of determinations CT stored in the counter. Here, initialization means, for example, setting the counted number of determinations to "0." When step S112 is executed, the flow ends.

[0034] When estimating the full charge capacity of a battery, if the change in the state of charge is relatively small, the error in detecting the voltage value, etc., becomes relatively large compared to the change in the state of charge. In this case, the estimated value of the full charge capacity of the battery obtained using the change in the state of charge becomes relatively low in accuracy. Therefore, by performing full charge capacity estimation only when the change in the state of charge is relatively large, a relatively accurate estimation result can be obtained. However, according to the knowledge of the present inventors, there may be cases where the change in the state of charge is so great that full charge capacity estimation is not performed, and continues for a relatively long period of time. For example, this may occur when the electric vehicle equipped with the battery is driven for a relatively short period of time. In such cases, because full charge capacity estimation is not performed for a relatively long period of time, there is a possibility that the last estimated full charge capacity of the battery may differ from the actual full charge capacity of the battery.

[0035] According to the battery full charge capacity estimation method of this embodiment, in the battery system 100 managed by the control unit 20 (battery management system), an estimated value Hx of the full charge capacity of the battery 1 is calculated using the current integration value ΣA1 and the change amount ΔSOC. The current integration value ΣA1 and the change amount ΔSOC are calculated based on values ​​detected by the sensor 30. The estimated value Hx is calculated and acquired by the estimation unit 46 when ΔSOC is equal to or greater than the threshold value Tx. In step S105 described above, the threshold value Tx is set to the first threshold value T1. When |ΔSOC| is smaller than the first threshold value T1, the number of determinations CT stored in the counting unit 48 is increased (step S110). When the number of determinations CT reaches the first number N1, the estimation unit 46 changes the threshold value Tx from the first threshold value T1 to a second threshold value T2. The second threshold value T2 is a value smaller than the first threshold value T1. That is, when the number of determinations CT reaches the first number N1, the value of the threshold Tx is relaxed, making it easier to calculate the estimated value Hx compared to when the threshold Tx is the first threshold T1. This prevents the calculation of the estimated value Hx from being suspended for a relatively long period of time. This prevents the occurrence of a discrepancy between the estimated value Hx and the actual full charge capacity of the battery 1. Therefore, it is possible to estimate the full charge capacity of the battery 1 with relatively high accuracy, regardless of the magnitude of the change amount ΔSOC.

[0036] In the first embodiment described above, the threshold Tx varies among three values, namely, the first threshold T1, the second threshold T2, and the third threshold T3. However, this is not limiting. The threshold Tx may vary among two or four or more values. Furthermore, the threshold Tx may be given, for example, by a curved equation relative to the number of determinations CT. That is, as shown by the dashed line in FIG. 5, a curve TL of the equation of the threshold Tx relative to the number of determinations CT may be given. In this case, the threshold Tx is determined according to the number of determinations CT stored in the counter 48.

[0037] In the above-described embodiment, the counting unit 48 initializes the number of determinations CT when it is determined that |ΔSOC| is equal to or greater than the first threshold T1 or the second threshold T2. However, this is not limiting. In such a case, the counting unit 48 may store a value obtained by subtracting a predetermined value from the number of determinations CT. Alternatively, the counting unit 48 may store a value obtained by dividing the number of determinations CT by a predetermined value.

[0038] The above-described embodiment is merely one example of the fully charged capacity estimation of a battery disclosed herein. The technology disclosed herein can be implemented in various other forms. Other embodiments of the technology disclosed herein will be described below.

[0039] Second Embodiment For example, in the first embodiment described above, whether or not to relax the threshold Tx is determined based on the number of times that |ΔSOC| is determined to be smaller than the threshold Tx, but this is not limiting. Fig. 6 is a flowchart for estimating the full charge capacity of the battery 1 according to a second embodiment. Note that the flow shown in Fig. 6 is also performed at time t3 (see Fig. 2), similar to the first embodiment. However, the timing at which the flow starts is not limited to this.

[0040] Steps S201 to S204 shown in FIG. 6 are the same as steps S101 to S104 shown in FIG. 3, and therefore a description thereof will be omitted here.

[0041] Step S205 shown in FIG. 6 is a process of acquiring an unexecuted time Pt, which is the time elapsed without acquiring an estimated value Hx since the previous acquisition of the estimated value Hx. Step S205 can be implemented by the unexecuted time measurement unit 50 (see FIG. 1) and the unexecuted time acquisition unit 51 (see FIG. 1) of the control device 40. The unexecuted time measurement unit 50 starts measuring time from the time the estimation unit 46 previously calculated the estimated value Hx. That is, when the estimation unit 46 calculates the estimated value Hx, the unexecuted time measurement unit 50 initializes the measured unexecuted time Pt ​​and starts measuring again. Here, "initializing the measured unexecuted time Pt" refers to, for example, setting the value of the measured unexecuted time Pt ​​to 0. In step S205, the unexecuted time acquisition unit 51 of the control device 40 acquires the unexecuted time Pt ​​measured by the unexecuted time measurement unit 50. That is, the elapsed time from the calculation of the previous estimated value Hx until step S205 is acquired. The order in which step S205 is performed is not limited to the order shown in Fig. 6. Step S205 may be performed before step S207 is performed.

[0042] Step S206 is a step of determining whether the absolute value |ΔSOC| of the change amount ΔSOC is lower than a predetermined threshold value Tx. Step S206 is similar to step S105 (see FIG. 3) in the first embodiment, and therefore a detailed description thereof will be omitted here. If it is determined in step S206 that |ΔSOC| is lower than the first threshold value T1, the process proceeds to step S207. If it is determined that |ΔSOC| is equal to or greater than the first threshold value, the flow ends.

[0043] Step S207 is a process of determining whether the unexecuted time Pt ​​acquired by the unexecuted time acquisition unit 51 is equal to or greater than a predetermined time. Step S207 can be implemented by the time determination unit 52 (see FIG. 1) of the control device 40. In this embodiment, the time determination unit 52 determines whether the unexecuted time Pt ​​is equal to or greater than an upper limit time P1. The value of the upper limit time P1 is not particularly limited, but is, for example, about one week to one month. If it is determined in step S207 that the unexecuted time Pt ​​is equal to or greater than the upper limit time P1, the estimation unit 46 changes the threshold value Tx from the first threshold value T1 to the second threshold value T2. Thereafter, the process proceeds to step S208. If it is determined that the unexecuted time Pt ​​is less than the upper limit time P1, the flow ends.

[0044] Step S208 is a process of determining whether |ΔSOC| is lower than a predetermined threshold value Tx. As described above, in step S207, the threshold value Tx is set to the second threshold value T2. Therefore, in step S208, it is determined whether |ΔSOC| is lower than the predetermined second threshold value T2. The determination in step S208 can be performed by the determination unit 47 (see FIG. 1). If it is determined in step S208 that |ΔSOC| is lower than the second threshold value T2, the flow ends. If it is determined that the value of |ΔSOC| is not lower than the second threshold value T2, that is, if it is determined that the value of |ΔSOC| is equal to or greater than the second threshold value T2, the flow proceeds to step S209.

[0045] Step S209 is a process of acquiring an estimated value Hx of the full charge capacity of the battery 1 based on equation (1) when it is determined that |ΔSOC| is equal to or greater than a predetermined second threshold T2. Step S209 can be implemented by the estimation unit 46.

[0046] Step S210 is a process of initializing the unexecuted time Pt. In step S210, the unexecuted time measurement unit 50 initializes the unexecuted time Pt ​​that it is measuring. Here, the unexecuted time measurement unit 50 sets the unexecuted time Pt ​​to "0." When step S210 is executed, the flow ends.

[0047] As described above, according to the method for estimating the full charge capacity of the battery 1 of the second embodiment, when it is determined that the unexecuted time Pt ​​is equal to or greater than the upper limit time P1, the threshold value Tx is changed from the first threshold value T1 to the second threshold value T2. Therefore, when the upper limit time P1 has elapsed since the previous calculation of the estimated value Hx, the threshold value Tx is relaxed regardless of whether |ΔSOC| is lower than the first threshold value T1. For example, when the ignition is turned on / off relatively infrequently (when the electric vehicle equipped with the battery system 100 is driven relatively infrequently), the number of times the determination unit 47 performs the determination may be relatively small. Therefore, there is a possibility that a discrepancy may occur between the previously acquired estimated value Hx and the actual full charge capacity of the battery 1. However, according to the method for estimating the full charge capacity of the battery 1 of the present embodiment, when the upper limit time P1 has elapsed since the previous calculation of the estimated value Hx, the threshold value Tx is relaxed. Therefore, estimation of the estimated value Hx is performed relatively frequently. This makes it possible to prevent the occurrence of a discrepancy between the estimated value Hx and the actual full charge capacity of the battery 1.

[0048] In the second embodiment described above, the threshold value Tx is changed using the first threshold value T1 and the second threshold value T2, but this is not limiting. The threshold value Tx may be changed two or more times. For example, the time determination unit 52 may make a determination using an upper limit time P1 and a time longer than the upper limit time P1.

[0049] In the second embodiment described above, after determining whether |ΔSOC| is lower than the first threshold T1 (step S206), determining whether the unexecuted time Pt ​​is equal to or greater than the upper limit time P1 (step S207) is performed. However, this is not limiting. Step S207 may be performed before step S206. In this case, when it is determined that the unexecuted time Pt ​​is equal to or greater than the upper limit time P1, the step of determining whether |ΔSOC| is lower than the first threshold T1 may be omitted.

[0050] Third Embodiment For example, in the first embodiment described above, whether or not to relax the threshold Tx is determined based on the number of times that |ΔSOC| is determined to be smaller than the threshold Tx, but this is not limiting. Fig. 7 is a flowchart for estimating the full charge capacity of the battery 1 according to a third embodiment. Note that the flow shown in Fig. 7 is also performed at time t3 (see Fig. 2), similar to the first embodiment. However, the timing at which the flow starts is not limited to this.

[0051] Steps S301 to S304 shown in FIG. 7 are the same as steps S101 to S104 shown in FIG. 3, and therefore a description thereof will be omitted here.

[0052] Step S305 shown in FIG. 7 is a process of acquiring a mileage Dt, which is the distance traveled by an electric vehicle equipped with the battery system 100 since the estimated value Hx was previously acquired. Step S305 can be implemented by the mileage measurement unit 53 (see FIG. 1) and the mileage acquisition unit 54 (see FIG. 1) of the control device 40. The mileage measurement unit 53 of the control device 40 starts measuring the mileage Dt from the time the estimation unit 46 previously calculated the estimated value Hx. That is, when the estimation unit 46 acquires the estimated value Hx, the mileage measurement unit 53 initializes the measured mileage Dt and starts measuring again. Here, "initializing the measured distance" refers, for example, to setting the measured mileage to zero. In step S305, the mileage acquisition unit 54 of the control device 40 acquires the mileage Dt measured by the mileage measurement unit 53. That is, the mileage from the time the estimated value Hx was previously calculated until step S305 is acquired. The order in which step S305 is executed is not limited to the order shown in Fig. 7. It is sufficient that step S305 is executed before step S307 is executed.

[0053] Step S306 is a step of determining whether the absolute value |ΔSOC| of the change amount ΔSOC is lower than a predetermined threshold value Tx. Step S306 is similar to step S105 (see FIG. 3) in the first embodiment, and therefore a detailed description will be omitted here. If it is determined in step S306 that |ΔSOC| is lower than the first threshold value T1, the process proceeds to step S307. If it is determined that |ΔSOC| is equal to or greater than the first threshold value, the flow ends.

[0054] Step S307 is a process of determining whether the traveled distance Dt acquired by the traveled distance measurement unit 53 is equal to or greater than a predetermined distance. Step S307 can be implemented by the distance determination unit 55 (see FIG. 1). In this embodiment, the distance determination unit 55 determines whether the traveled distance Dt is equal to or greater than an upper limit distance D1. The value of the upper limit distance D1 is not particularly limited, but is, for example, approximately 1000 km to 10000 km. If it is determined in step S307 that the traveled distance Dt is equal to or greater than the upper limit distance D1, the estimation unit 46 changes the threshold value Tx from the first threshold value T1 to the second threshold value T2. Thereafter, the process proceeds to step S308. If it is determined that the traveled distance Dt is less than the upper limit distance D1, the flow ends.

[0055] Step S308 is a step of determining whether |ΔSOC| is lower than a predetermined threshold value Tx. In step S308, the threshold value Tx is set to a second threshold value T2. Step S308 is similar to step S208 in the second embodiment (see FIG. 6), and therefore a description thereof will be omitted.

[0056] Step S309 is a process of acquiring an estimated value Hx of the full charge capacity of the battery 1 based on equation (1) when it is determined that |ΔSOC| is equal to or greater than a predetermined second threshold T2. Step S309 can be implemented by the estimation unit 46.

[0057] Step S310 is a step of initializing the traveled distance Dt. In step S310, the traveled distance measurement unit 53 initializes the measured traveled distance Dt. Here, the traveled distance measurement unit 53 sets the unexecuted time Pt ​​to "0." When step S310 is executed, the flow ends.

[0058] As described above, according to the method for estimating the full charge capacity of the battery 1 of the third embodiment, when it is determined that the traveled distance Dt is equal to or greater than the upper limit distance D1, the threshold value Tx is changed from the first threshold value T1 to the second threshold value T2. Therefore, if the vehicle has traveled a distance equal to or greater than the upper limit distance D1 since the previous calculation of the estimated value Hx, the threshold value Tx is relaxed regardless of whether |ΔSOC| is lower than the first threshold value T1. For example, if the traveled distance per driving session (from when the ignition is turned on to when the ignition is turned off) of the electric vehicle is relatively long, the number of times the determination unit 47 performs the determination may be relatively small depending on the charging and discharging during driving. Furthermore, as the traveled distance increases, the full charge capacity of the battery 1 deteriorates. Therefore, at this time, a discrepancy may occur between the previously calculated estimated value Hx and the actual full charge capacity of the battery 1. However, according to the method for estimating the full charge capacity of the battery 1 of the present embodiment, the threshold value Tx is relaxed if the traveled distance Dt is equal to or greater than the upper limit distance D1. Therefore, estimation of the estimated value Hx is performed relatively frequently, which prevents the estimated value Hx from not being obtained for a relatively long period of time even when the travel distance is relatively long, and prevents the estimated value Hx from deviating from the actual full charge capacity of the battery 1.

[0059] In the third embodiment described above, the threshold value Tx is changed using the first threshold value T1 and the second threshold value T2, but this is not limiting. The threshold value Tx may be changed two or more times. For example, the distance determination unit 55 may perform determination using the upper limit distance D1 and a distance longer than the upper limit distance D1.

[0060] In the third embodiment described above, after determining whether |ΔSOC| is lower than the first threshold T1 (step S306), the process determines whether the traveled distance Dt is equal to or greater than the upper limit distance D1 (step S307). However, this is not limiting. Step S307 may be performed before step S306. In this case, when it is determined that the non-execution time Pt ​​is equal to or greater than the upper limit distance D1, the process of determining whether |ΔSOC| is lower than the first threshold T1 may be omitted.

[0061] Fourth Embodiment For example, in the third embodiment described above, the threshold value Tx is changed from the first threshold value to the second threshold value by comparing the travel distance Dt with a predetermined travel distance (upper limit distance D1), but this is not limited to this. Fig. 8 is a flowchart for estimating the full charge capacity of the battery 1 according to a fourth embodiment. As with the first embodiment, the flow shown in Fig. 8 is also assumed to be performed at time t3 (see Fig. 2). However, the timing at which the flow is started is not limited to this.

[0062] Steps S401 to S404 shown in FIG. 8 are the same as steps S101 to S104 shown in FIG. 3, and therefore a description thereof will be omitted here.

[0063] Step S405 shown in Fig. 8 is a step of acquiring a full charge capacity Hm (hereinafter simply referred to as "full charge capacity Hm") in a capacity degradation model that is pre-recorded regarding predetermined information about the battery 1 and the full charge capacity of the battery 1. The capacity degradation model DM (see Fig. 9) in this embodiment is a model that shows the relationship between the mileage Dt traveled by an electric vehicle equipped with the battery system 100 and the full charge capacity of the battery 1. The mileage Dt is the same as the mileage Dt in the third embodiment.

[0064] FIG. 9 is a diagram showing a capacity degradation model DM of the battery 1. The capacity degradation model DM is a graph showing the relationship between the mileage of an electric vehicle equipped with the battery system 100 and the full charge capacity of the battery 1. The vertical axis of the capacity degradation model DM represents the full charge capacity. The horizontal axis of the capacity degradation model DM represents the mileage of the electric vehicle. The capacity degradation model DM is acquired in advance by testing, simulation, theoretical calculation, etc., and is stored in the control device 40. In step S405, as in the third embodiment, the mileage acquisition unit 54 (see FIG. 1) acquires the mileage Dt. The estimated capacity acquisition unit 56 (see FIG. 1) of the control device 40 acquires the full charge capacity Hm at the mileage Dt from the capacity degradation model DM.

[0065] Step S406 shown in Fig. 8 is a process for obtaining an estimated value Hx of the full charge capacity of the battery 1. Note that step S406 includes steps S411 to S417.

[0066] Step S411 is a step in which the estimation unit 46 calculates the estimated value Hx based on Equation (1). Step S412 is a step in which it is determined whether the estimated value Hx and the mileage Dt differ by a predetermined value or more with respect to a capacity degradation model DM pre-recorded based on predetermined information and the full charge capacity. Step S412 can be implemented by the estimated value determination unit 57 (see FIG. 1) of the control device 40. In this embodiment, the estimated value determination unit 57 determines whether the estimated value Hx estimated by the estimation unit 46 and the mileage Dt differ by a predetermined value or more with respect to the capacity degradation model DM. In this embodiment, the estimated value determination unit 57 determines whether the absolute value |Hx - Hm| of the difference between the estimated value Hx and the full charge capacity Hm of the capacity degradation model DM is equal to or greater than a predetermined threshold value Ht. The value of the threshold value Ht is not particularly limited. If it is determined in step S412 that |Hx - Hm| is equal to or greater than Ht, the process proceeds to step S413. If it is determined in step S412 that |Hx-Hm| is smaller than Ht, the process proceeds to step S414.

[0067] Step S413 is a step of acquiring an estimated value Hx of the full charge capacity, in which the first threshold T1 is set to the second threshold T2. Since it is determined in step S412 that |Hx - Hm| is equal to or greater than Ht, in step S413 the estimation unit 46 changes the threshold Tx from the first threshold T1 to the second threshold T2, regardless of the number of determinations CT stored in the counting unit 48 (see FIG. 1). Step S414 is a step of setting the threshold Tx to the first threshold T1. Since it is determined in step S412 that |Hx - Hm| is smaller than Ht, in step S414 the estimation unit 46 leaves the threshold Tx at the first threshold T1. After step S413 or step S414 is executed, the process proceeds to step S415.

[0068] Step S415 is a step of determining whether |ΔSOC| is lower than a predetermined threshold value Tx. If the threshold value Tx is set to the second threshold value T2 in step S413, the determination is made using the second threshold value T2 in step S415. If the threshold value Tx is set to the first threshold value T1 in step S414, the determination is made using the first threshold value T1 in step S415. Step S415 is executed by the determination unit 47 (see FIG. 1). If it is determined in step S415 that |ΔSOC| is lower than the threshold value Tx, the process proceeds to step S416. If it is determined that |ΔSOC| is equal to or greater than the threshold value Tx, the process proceeds to step S417.

[0069] Step S416 is a step of deciding not to use the estimated value Hx as an estimated value of the full charge capacity of the battery 1. Since it was determined in step S415 that |ΔSOC| is lower than the threshold Tx, the control device 40 does not use the estimated value Hx calculated by the estimating unit 46 in step S411 as an estimated value of the full charge capacity of the battery 1. At this time, the calculated estimated value Hx is erased. Step S417 is a step of using the estimated value Hx as an estimated value of the full charge capacity of the battery 1. Since it was determined in step S415 that |ΔSOC| is equal to or greater than the threshold Tx, the control device 40 uses the estimated value Hx calculated by the estimating unit 46 in step S411 as an estimated value of the full charge capacity of the battery 1.

[0070] As described above, according to the method for estimating the full charge capacity of the battery 1 of the fourth embodiment, when the estimated value determination unit 57 determines that |Hx - Hm| is equal to or greater than Ht, the threshold value Tx is changed from the first threshold value T1 to the second threshold value T2. Therefore, when there is a difference with respect to the capacity degradation model DM that is equal to or greater than a predetermined value, the conditions for calculating the estimated value Hx are relaxed regardless of whether |ΔSOC| is lower than the first threshold value T1. Depending on the usage conditions of the electric vehicle, the full charge capacity of the battery 1 may deviate relatively significantly from the capacity degradation model DM. Relaxing the conditions for obtaining the estimated value Hx increases the number of times the estimated value Hx is calculated and obtained. This allows the obtained estimated value Hx to gradually approach the capacity degradation model DM.

[0071] In the fourth embodiment described above, in step S412, it is determined whether the absolute value |Hx-Hm| of the difference between the estimated value Hx and the full charge capacity Hm is greater than a predetermined threshold value Ht. However, this is not limiting. Whether the difference with respect to the capacity degradation model DM is equal to or greater than a predetermined value may be determined based on the mileage. That is, it may be determined whether the difference between the mileage corresponding to the estimated value Hx and the mileage Dt is equal to or greater than a predetermined value in the capacity degradation model DM.

[0072] In the above-described fourth embodiment, the capacity degradation model DM is a model that shows the relationship between the mileage Dt and the full charge capacity of the battery 1. However, the capacity degradation model is not limited to this. For example, the capacity degradation model may be a model that is pre-recorded with respect to information such as the temperature, SOC, and ΔSOC of the battery 1 during use, and the full charge capacity of the battery 1.

[0073] In the above-described embodiments, the threshold value Tx is a threshold value for ΔSOC, but is not limited to this. The threshold value Tx may be, for example, a threshold value for the current integrated value ΣA1. In this case, the determination unit 47 determines whether the current integrated value ΣA1 is lower than a predetermined threshold. Alternatively, the threshold value Tx may be a value that determines whether the time during which the current integrated value ΣA1 is acquired, or the time from when the ignition is turned on to when it is turned off, is lower than a predetermined threshold.

[0074] The full charge capacity estimation program 40a of this embodiment may be stored in, for example, a non-transitory computer readable medium. The program may also be supplied to a computer through such a non-transitory computer readable medium. Examples of non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), CD-ROMs (Read Only Memory), etc.

[0075] The invention disclosed herein has been described in detail above. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein may be modified in various ways, and components and processes described herein may be omitted or combined as appropriate, provided that no particular problems arise. For example, the threshold value Tx may be set using the determination of the number of determinations CT by the count determination unit 49 and the determination of the unexecuted time Pt ​​by the time determination unit 52. The estimation unit 46 may change the first threshold value T1 to the second threshold value T2 when either the determination by the count determination unit 49 or the determination by the time determination unit 52 is satisfied.

[0076] As described above, this specification includes the disclosures set forth in the following sections.

[0077] Section 1: A method for estimating a full charge capacity of a battery managed by a BMS (battery management system) mounted on an electric vehicle, comprising: obtaining an SOC1, which is an SOC obtained based on a voltage V1, which is an OCV of the battery; acquiring an SOC2 that is an SOC obtained based on a voltage V2 that is an OCV of the battery at a time later than the state in which the SOC of the battery is SOC1; acquiring a change ΔSOC between the SOC1 and the SOC2; acquiring an integrated current value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; When |ΔSOC| is equal to or greater than a predetermined first threshold, acquiring an estimated value Hx of the full charge capacity of the battery based on equation (1); Including, Formula (1): Hx = (ΣA1 / ΔSOC) × 100 wherein, in the step of acquiring the estimated value Hx of the full charge capacity, when a predetermined condition is satisfied, the first threshold value is set to a second threshold value that is lower than the first threshold value. A method for estimating the full charge capacity of a battery.

[0078] Section 2: Item 2. The method for estimating a full charge capacity of a battery according to Item 1, wherein the predetermined condition is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

[0079] Section 3: The method further includes a step of acquiring an unexecuted time, which is a time that has elapsed since the previous acquisition of the estimated value Hx without the acquisition of the estimated value Hx; 3. The method for estimating a full charge capacity of a battery according to item 1 or 2, wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

[0080] Section 4: The method further includes a step of acquiring a travel distance that is a distance that the electric vehicle has traveled since the estimated value Hx was last acquired, 4. The method for estimating a full charge capacity of a battery according to any one of items 1 to 3, wherein the predetermined condition is that the traveled distance is equal to or greater than a predetermined distance.

[0081] Section 5: 5. The method for estimating the full charge capacity of a battery according to any one of items 1 to 4, wherein the predetermined condition is that the predetermined information or the estimated value Hx differs by a predetermined value or more from a capacity degradation model pre-recorded regarding predetermined information about the battery and the full charge capacity of the battery.

[0082] Item 6: A full charge capacity estimation device that estimates capacity deterioration of a battery managed by a BMS (battery management system) mounted on an electric vehicle, A sensor, a control device; The sensor A voltage sensor; a current sensor; Equipped with The control device a first state of charge acquisition unit that acquires an SOC1 that is an SOC obtained based on a voltage V1 that is an OCV of the battery detected by the sensor; a second state-of-charge acquisition unit that acquires SOC2, which is an SOC obtained based on a voltage V2 that is an OCV of the battery detected by the sensor at a time point after the SOC of the battery is SOC1; a change amount acquisition unit that acquires a change amount ΔSOC between the SOC1 and the SOC2; a current integration value acquisition unit that acquires a current integration value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; an estimation unit that acquires an estimated value Hx of the full charge capacity of the battery based on equation (1) when |ΔSOC| is equal to or greater than a predetermined first threshold; Equipped with Formula (1): Hx = (ΣA1 / ΔSOC) × 100 wherein, when a predetermined condition is satisfied, the estimation unit sets the first threshold to a second threshold that is lower than the first threshold. Battery full charge capacity estimation device.

[0083] Section 7: 7. The battery full charge capacity estimation device according to item 6, wherein the predetermined condition is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

[0084] Section 8: the control device includes an unexecuted time acquisition unit that acquires an unexecuted time, which is a time that has elapsed since the previous acquisition of the estimated value Hx without the estimate value Hx being acquired; 8. The battery full charge capacity estimation device according to item 6 or 7, wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

[0085] Section 9: the control device includes a travel distance acquisition unit that measures a travel distance that is a distance traveled by the electric vehicle since the estimated value Hx was previously acquired, 9. The battery full charge capacity estimation device according to any one of items 6 to 8, wherein the predetermined condition is that the traveled distance is equal to or greater than a predetermined distance.

[0086] Section 10: 10. The battery full charge capacity estimation device according to any one of items 6 to 9, wherein the predetermined condition is that the predetermined information or the estimated value Hx has a difference of a predetermined value or more with respect to predetermined information of the battery and a pre-recorded capacity degradation model regarding the full charge capacity of the battery.

[0087] Section 11: A full charge capacity estimation program that estimates the capacity deterioration of a battery managed by a BMS (battery management system) mounted on an electric vehicle, a first state of charge acquisition unit that acquires an SOC1 that is an SOC obtained based on a voltage V1 that is an OCV of the battery; a second state-of-charge acquisition unit that acquires an SOC2 that is an SOC obtained based on a voltage V2 that is an OCV of the battery at a time later than the state in which the SOC of the battery is the SOC1; a change amount acquisition unit that acquires a change amount ΔSOC between the SOC1 and the SOC2; a current integration value acquisition unit that acquires a current integration value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; an estimation unit that acquires an estimated value Hx of the full charge capacity of the battery based on equation (1) when |ΔSOC| is equal to or greater than a predetermined first threshold; configured to cause a computer to realize Formula (1): Hx = (ΣA1 / ΔSOC) × 100 wherein, when a predetermined condition is satisfied, the estimation unit sets the first threshold to a second threshold that is lower than the first threshold. A program to estimate the full charge capacity of a battery.

[0088] Section 12: Item 12. The battery full charge capacity estimation program according to Item 11, wherein the predetermined condition is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

[0089] Section 13: The computer is further configured to implement an unexecuted time measurement unit that acquires an unexecuted time, which is a time that has elapsed since the estimated value Hx was last acquired without the estimated value Hx being acquired, Item 13. The battery full charge capacity estimation program according to item 11 or 12, wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

[0090] Section 14: The computer is further configured to implement a mileage acquisition unit that acquires a mileage that is a distance that the electric vehicle has traveled since the estimated value Hx was last acquired, Item 14. The battery full charge capacity estimation program according to any one of Items 11 to 13, wherein the predetermined condition is that the traveled distance is equal to or greater than a predetermined distance.

[0091] Section 15: 15. The battery full charge capacity estimation program according to any one of items 11 to 14, wherein the predetermined condition is that the predetermined information or the estimated value Hx has a difference of a predetermined value or more with respect to predetermined information of the battery and a pre-recorded capacity degradation model regarding the full charge capacity of the battery. [Explanation of symbols]

[0092] 1 battery 20 Control Unit 30 sensors 31 Voltage sensor 32 Temperature Sensor 33 Current Sensor 40 Control device 40a Full charge capacity estimation program 41 Storage section 42 First charge state acquisition unit 43 Second charging state acquisition unit 44 Change amount acquisition unit 45 Current integration value acquisition unit 46 Estimation part 47 Judgment section 48 Counting Unit 49 Number of times determination unit 50 Unexecuted time measurement section 51 Unexecuted time acquisition unit 52 Time determination section 53 Odometer unit 54 Mileage acquisition unit 55 Distance determination unit 56 Estimated capacity acquisition part 57 Estimated value determination unit 100 Battery System A1,A2,A3,A4 area CT determination count D1 Upper limit distance DM capacity degradation model Dt mileage GP graph Hm Full charge capacity Ht threshold Hx estimate P1 upper limit time Pt Unexecuted time TL curve Tx Threshold T1 First threshold T2 Second threshold V1, V2 voltage ΔSOC change ΣA1 Current integrated value

Claims

1. A method for estimating a full charge capacity of a battery managed by a BMS (battery management system) mounted on an electric vehicle, comprising: obtaining an SOC1 that is an SOC obtained based on a voltage V1 that is an OCV of the battery; acquiring an SOC2 that is an SOC obtained based on a voltage V2 that is an OCV of the battery at a time later than a state in which the SOC of the battery is SOC1; acquiring a change amount ΔSOC between the SOC1 and the SOC2; acquiring an integrated current value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; When |ΔSOC| is equal to or greater than a predetermined first threshold, acquiring an estimated value Hx of a full charge capacity of the battery based on equation (1); Including, Formula (1): Hx=(ΣA1 / ΔSOC)×100 wherein, in the step of acquiring the estimated value Hx of the full charge capacity, when a predetermined condition is satisfied, the first threshold value is set to a second threshold value that is lower than the first threshold value. 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 is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

3. The method further includes a step of acquiring an unexecuted time, which is a time that has elapsed since the previous acquisition of the estimated value Hx without the acquisition of the estimated value Hx; The method for estimating a full charge capacity of a battery according to claim 1 , wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

4. The method further includes a step of acquiring a travel distance that is a distance that the electric vehicle has traveled since the estimated value Hx was last acquired, The method for estimating a full charge capacity of a battery according to claim 1 , wherein the predetermined condition is that the traveled distance is equal to or greater than a predetermined distance.

5. 2. The method for estimating the full charge capacity of a battery according to claim 1, wherein the predetermined condition is that the predetermined information or the estimated value Hx differs by a predetermined value or more from a capacity degradation model prerecorded regarding predetermined information about the battery and the full charge capacity of the battery.

6. A full charge capacity estimation device that estimates capacity degradation of a battery managed by a BMS (battery management system) mounted on an electric vehicle, A sensor, a control device; The sensor A voltage sensor; a current sensor; Equipped with The control device a first state-of-charge acquisition unit that acquires an SOC1 that is an SOC obtained based on a voltage V1 that is an OCV of the battery detected by the sensor; a second state-of-charge acquisition unit that acquires an SOC2 that is an SOC obtained based on a voltage V2 that is an OCV of the battery detected by the sensor at a time point after the SOC of the battery is the SOC1; and a change amount acquisition unit that acquires a change amount ΔSOC between the SOC1 and the SOC2; a current integration value acquisition unit that acquires a current integration value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; an estimation unit that acquires an estimated value Hx of a full charge capacity of the battery based on equation (1) when |ΔSOC| is equal to or greater than a predetermined first threshold; Equipped with Formula (1): Hx=(ΣA1 / ΔSOC)×100 wherein, when a predetermined condition is satisfied, the estimation unit sets the first threshold to a second threshold that is lower than the first threshold. Battery full charge capacity estimation device.

7. 7. The battery full charge capacity estimating device according to claim 6, wherein the predetermined condition is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

8. the control device includes an unexecuted time acquisition unit that acquires an unexecuted time, which is a time that has elapsed since the previous acquisition of the estimated value Hx without the estimate value Hx being acquired; 7. The battery full charge capacity estimation device according to claim 6, wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

9. the control device includes a travel distance acquisition unit that measures a travel distance that is a distance traveled by the electric vehicle since the estimated value Hx was previously acquired, 7. The battery full charge capacity estimating device according to claim 6, wherein the predetermined condition is that the traveled distance is equal to or greater than a predetermined distance.

10. 7. The battery full charge capacity estimation device according to claim 6, wherein the predetermined condition is that the predetermined information or the estimated value Hx differs by a predetermined value or more from predetermined information about the battery and a pre-recorded capacity degradation model regarding the full charge capacity of the battery.

11. A full charge capacity estimation program for estimating capacity deterioration of a battery managed by a BMS (battery management system) mounted on an electric vehicle, a first state of charge acquisition unit that acquires an SOC1 that is an SOC obtained based on a voltage V1 that is an OCV of the battery; a second state-of-charge acquisition unit that acquires an SOC2 that is an SOC obtained based on a voltage V2 that is an OCV of the battery at a time later than a time when the SOC of the battery is the SOC1; a change amount acquisition unit that acquires a change amount ΔSOC between the SOC1 and the SOC2; a current integration value acquisition unit that acquires a current integration value ΣA1 of the battery until the SOC changes from the SOC1 to the SOC2; an estimation unit that acquires an estimated value Hx of a full charge capacity of the battery based on equation (1) when |ΔSOC| is equal to or greater than a predetermined first threshold; configured to cause a computer to realize Formula (1): Hx=(ΣA1 / ΔSOC)×100 wherein, when a predetermined condition is satisfied, the estimation unit sets the first threshold to a second threshold that is lower than the first threshold. A program to estimate the full charge capacity of a battery.

12. 12. The battery full charge capacity estimation program according to claim 11, wherein the predetermined condition is that |ΔSOC| is lower than the first threshold value a predetermined number of times in succession.

13. The computer is further configured to implement an unexecuted time measurement unit that acquires an unexecuted time, which is a time that has elapsed since the previous acquisition of the estimated value Hx without the acquisition of the estimated value Hx, The battery full charge capacity estimation program according to claim 11 , wherein the predetermined condition is that the non-execution time is equal to or longer than a predetermined time.

14. The computer is further configured to implement a mileage acquisition unit that acquires a mileage that is a distance that the electric vehicle has traveled since the estimated value Hx was last acquired, The battery full charge capacity estimation program according to claim 11 , wherein the predetermined condition is that the travel distance is equal to or greater than a predetermined distance.

15. 12. The battery full charge capacity estimation program of claim 11, wherein the predetermined condition is that the predetermined information or the estimated value Hx has a difference of a predetermined value or more with respect to predetermined information of the battery and a pre-recorded capacity degradation model regarding the full charge capacity of the battery.

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