SOC estimation device

Abstract

A processor of the SOC estimation device executes: drawing data in which the correction index corresponding to the stroke period to which the end-time SOC belongs and the absolute current amount integrated value up to the stroke period to which the end-time SOC belongs are associated; determining whether the polarization of the battery is eliminated at the start of the stroke period; when it is determined that the polarization of the battery is not eliminated, deriving, on the basis of the past drawing data, an estimated value of the correction index corresponding to the stroke period preceding the stroke period to which the current point in time belongs; and deriving, on the basis of the estimated value of the correction index, an initial value of the SOC during the stroke to which the current point in time belongs.

Description

Technical Field

[0001] The present invention relates to a SOC estimating device for estimating the SOC (State Of Charge) of a battery. Background Art

[0002] For example, a technique for estimating SOC by an open circuit voltage method and a technique for estimating SOC by a current integration method are disclosed in Patent Document 1. In Patent Document 1, a reference time is set using a total error obtained by adding an error value of SOC obtained by an open circuit voltage method and an error value of SOC obtained by a current integration method, and SOC is estimated using the set reference time.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-202551 Summary of the invention

[0006] Technical issues

[0007] In the current integration method, the change amount of SOC based on the initial value of SOC is derived based on the current integration value, and the SOC is estimated by adding the initial value of SOC to the change amount of SOC. The initial value of SOC is estimated, for example, by the open circuit voltage method. However, for example, when the polarization of the battery is not eliminated, it is difficult to estimate an appropriate initial value of SOC by the open circuit voltage method.

[0008] Therefore, an object of the present invention is to provide an SOC estimating device capable of estimating an appropriate initial value of SOC.

[0009] Technical Solution

[0010] In order to solve the above-mentioned problems, an SOC estimating device according to one embodiment of the present invention includes:

[0011] A battery, which is mounted on a vehicle; and

[0012] a control device that estimates the SOC of the battery,

[0013] The control device comprises:

[0014] one or more processors; and

[0015] one or more memories connected to the processor,

[0016] The period from the start of the vehicle preparation until it is ready is the travel period.

[0017] The processor performs the following processes, which include:

[0018] When the export ends, the difference between the SOC at the end and the SOC at the start is derived as a SOC correction amount showing the estimated error of the SOC corresponding to the travel period to which the SOC at the end belongs. The SOC at the end is the SOC estimated by the cumulative current method at the end of the travel period, and the SOC at the start is the SOC estimated by the open-circuit voltage method at the start of the next travel period after the travel period to which the SOC at the end belongs;

[0019] During the travel period, an absolute current amount is derived. The absolute current amount is a value obtained by adding the cumulative value of the absolute value of the charging current in the battery and the cumulative value of the absolute value of the discharging current in the battery;

[0020] The SOC correction amount corresponding to the travel period to which the SOC at the end belongs is divided by the absolute current amount during the travel period to which the SOC at the end belongs, and is derived as a correction index corresponding to the travel period to which the SOC at the end belongs;

[0021] An absolute current amount cumulative value is derived. The absolute current amount cumulative value is a value obtained by cumulatively adding the absolute current amounts over a plurality of travel periods starting from a predetermined reference time point;

[0022] Drawing data is generated. The drawing data is data obtained by associating the correction index corresponding to the travel period to which the SOC at the end belongs and the absolute current amount cumulative value up to the travel period to which the SOC at the end belongs;

[0023] At the start of the travel period, it is determined whether the polarization of the battery is eliminated;

[0024] When it is determined that the polarization of the battery is not eliminated, based on the past drawing data, an estimated value of the correction index corresponding to the previous travel period of the travel period to which the current time point belongs is derived; and

[0025] Based on the estimated value of the correction index, an initial value of the SOC of the travel period to which the current time point belongs is derived.

[0026] Technical effects

[0027] According to the present invention, an appropriate initial value of the SOC can be estimated. Description of the drawings

[0028] Figure 1 is a schematic block diagram showing the structure of a vehicle to which the SOC estimation device of the present embodiment is applied.

[0029] Figure 2 It is a diagram for explaining an example of the estimation method and estimation timing of SOC.

[0030] Figure 3 It is a diagram for explaining another example of the estimation method and estimation timing of SOC.

[0031] Figure 4 This is a diagram for explaining derivation of the initial SOC value based on the estimated value of the correction index.

[0032] Figure 5 It is a diagram explaining the relationship between the correction index and the allowable power.

[0033] Figure 6 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is an increasing tendency.

[0034] Figure 7 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is a decreasing tendency.

[0035] Figure 8 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is substantially constant.

[0036] Fig. 9 This is a flowchart illustrating the flow of operations of the SOC estimating unit.

[0037] Fig.10 It is explained in Fig. 9 Flowchart of the process of the process that the SOC estimating unit periodically repeats after the process until the vehicle becomes ready.

[0038] Fig.11 : is a flowchart explaining the flow of the SOC initial value derivation process.

[0039] Fig.12 1 is a flowchart illustrating the flow of full charge capacity update determination processing.

[0040] Fig.13 This is a flowchart illustrating the flow of correction value derivation processing.

[0041] Explanation of symbols

[0042] 1: Vehicle

[0043] 10: SOC estimation device

[0044] 20: Battery

[0045] 30: Control device

[0046] 40: Processor

[0047] 42: Memory DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The specific dimensions, materials, values, etc. shown in the embodiments are merely examples for easy understanding of the invention and do not limit the present invention unless otherwise specified. It should be noted that in this specification and the accompanying drawings, for elements having substantially the same function and structure, repeated descriptions are omitted by marking the same symbols, and illustrations of elements that are not directly related to the present invention are omitted.

[0049] Figure 1 1 is a schematic block diagram showing the structure of a vehicle 1 to which the SOC estimation device 10 of the present embodiment is applied. The vehicle 1 is, for example, an electric vehicle having a motor generator as a driving source. It should be noted that the vehicle 1 may also be a hybrid electric vehicle having an engine and a motor generator as driving sources.

[0050] The vehicle 1 includes a battery 20 , a voltage sensor 22 , a current sensor 24 , a storage device 26 , and a control device 30 .

[0051] The battery 20 is, for example, a secondary battery that can be charged and discharged, such as a lithium-ion battery. It should be noted that the battery 20 is not limited to a lithium-ion battery, and may be composed of any known composition that can be charged and discharged. The battery 20 is mounted on the vehicle 1. The battery 20 is, for example, a high-voltage battery, and supplies power to the electric generator. In addition, the electric power regenerated by the electric generator functioning as a generator is charged to the battery 20. In addition, the vehicle 1 may also be configured so that the battery 20 can be charged with power supplied from outside the vehicle 1.

[0052] The voltage sensor 22 is configured to detect the voltage of the battery 20. For example, when the battery 20 is electrically disconnected from the electrical system of the vehicle 1, the voltage sensor 22 can detect the open circuit voltage of the battery 20. Hereinafter, the open circuit voltage may be expressed as OCV.

[0053] The current sensor 24 is configured to be able to detect a charging current input to the battery 20 and a discharging current output from the battery 20 .

[0054] The storage device 26 is composed of a nonvolatile storage element. It should be noted that the nonvolatile storage element may include an electrically readable and writable nonvolatile storage element such as a flash memory. The storage device 26 can store various information and data related to the estimation of the SOC of the battery 20, for example.

[0055] The control device 30 includes one or more processors 40 and one or more memories 42 connected to the processors 40. The memories 42 include a ROM storing programs and a RAM as a work area. The processors 40 of the control device 30 cooperate with the programs contained in the memories 42 to control the entire vehicle 1.

[0056] More specifically, the processor 40 cooperates with the program to function as an SOC estimating unit 50 that estimates the SOC (State Of Charge) of the battery 20. The SOC indicates the charging rate of the current charging capacity of the battery 20 relative to the full charge capacity expressed as a percentage.

[0057] The SOC estimating unit 50 can estimate the SOC by an open circuit voltage method and can estimate the SOC by a current integration method. Hereinafter, the open circuit voltage method may be referred to as the OCV method.

[0058] The open circuit voltage method is an estimation method for estimating the SOC based on the open circuit voltage of the battery 20. For example, an open circuit voltage SOC map, which is a map that associates the open circuit voltage with the SOC one-to-one, is pre-stored in the memory 42. In the open circuit voltage method, the SOC estimation unit 50 applies the open circuit voltage of the battery 20 detected by the voltage sensor 22 to the open circuit voltage SOC map to derive the SOC.

[0059] The current integration method is a method of estimating the SOC based on the current integrated value obtained by integrating the charging current and discharging current of the battery 20 over time. In the current integration method, the SOC estimation unit 50 obtains the charging current and discharging current of the battery 20 that change over time due to the travel of the vehicle 1 through the current sensor 24. The SOC estimation unit 50 integrates the charging current and discharging current obtained each time and derives the current integrated value. The SOC estimation unit 50 divides the current integrated value by the full charge capacity and derives the change amount relative to the initial value of the SOC. The SOC estimation unit 50 adds the initial value to the change amount relative to the derived initial value and derives the current SOC.

[0060] Thus, in the current integration method, the estimation accuracy of SOC depends on three parameters: the current integration value, the full charge capacity, and the initial value of SOC. In contrast, in the open circuit voltage method, since the open circuit voltage SOC map is predetermined, the estimation accuracy of SOC depends only on the open circuit voltage detected by the voltage sensor 22. Therefore, compared with the current integration method, the open circuit voltage method can improve the estimation accuracy of SOC.

[0061] Since the open circuit voltage is detected with the battery 20 disconnected from the electrical system of the vehicle 1, the time when the SOC can be estimated is limited in the open circuit voltage method. In contrast, the SOC can be estimated while the vehicle 1 is running in the current integration method, and the SOC can be estimated without hindering the running of the vehicle 1.

[0062] Since the open circuit voltage method and the current integration method have the above-mentioned characteristics, estimation based on the open circuit voltage method and estimation based on the current integration method are used separately according to the situation.

[0063] Figure 2 This is a diagram for explaining an example of an estimation method and estimation time of SOC. Hereinafter, the period from the start of the preparation (ready-on) of the vehicle 1 to the ready-off is sometimes referred to as a trip period. That is, the start time point of the trip period is the time point when the vehicle 1 starts to prepare, and the end time point of the trip period is the time point when the vehicle 1 is ready.

[0064] like Figure 2 As shown, during the trip, the battery 20 is charged and discharged as the vehicle 1 travels, so the current of the battery 20 changes.

[0065] Here, when the battery 20 is charged, polarization occurs inside the battery 20. Polarization refers to a phenomenon in which a pseudo potential difference occurs due to electron bias between the positive and negative electrodes of the battery 20. When such polarization occurs, the voltage of the battery 20 detected by the voltage sensor 22 is detected as a value higher than the actual voltage by the pseudo potential difference. This results in a decrease in the accuracy of the SOC derived by the open circuit voltage method using the detection result of the voltage sensor 22.

[0066] Such polarization can be eliminated by standing by for a predetermined time without charging the battery 20 after charging. Therefore, when the next preparation starts after a predetermined time that can eliminate polarization has passed since the vehicle 1 was ready, the polarization of the battery 20 is eliminated.

[0067] Hereinafter, the time during which polarization can be eliminated may be referred to as polarization elimination time. The polarization elimination time is, for example, 30 minutes, but may be any time during which polarization can be eliminated in consideration of the type and performance of the battery 20 .

[0068] If polarization is eliminated, the pseudo potential difference substantially disappears, and the detection result of the voltage sensor 22 becomes substantially the same as the actual voltage. That is, by eliminating polarization, the accuracy of the SOC derived by the open circuit voltage method using the detection result of the voltage sensor 22 can be suppressed from decreasing.

[0069] exist Figure 2 In the example, time point T1 corresponds to the time point of preparation start, which is the time point at which the polarization elimination time or more has passed since the preparation of the previous trip period was ready. Time point T2 corresponds to the time point at which the trip period to which time point T1 belongs is ready. Time point T3 corresponds to the time point at which the next preparation starts in the trip period to which time point T1 belongs, which is the time point at which the polarization elimination time or more has passed since time point T2.

[0070] In addition, Figure 2 In the example, time point T3 is set as the current time point. In the following, the travel period to which the current time point belongs is sometimes referred to as the current travel period. The travel period before the travel period to which the current time point belongs is sometimes referred to as the previous travel period. Figure 2 In the example, the travel period to which the time point T3 belongs is the current travel period, and the travel period to which the time point T1 and the time point T2 belong is the previous travel period.

[0071] As described above, if polarization is eliminated, the accuracy of SOC by the OCV method can be suppressed from decreasing, so SOC estimating unit 50 determines whether polarization of battery 20 is eliminated at the time of preparation. If polarization of battery 20 is eliminated, SOC estimating unit 50 derives SOC by the OCV method.

[0072] exist Figure 2 In the example, since a time longer than the polarization elimination time has passed before the time point T1, the SOC estimating unit 50 can derive the SOC in the OCV method at the time point T1 of the preparation start. In addition, since a time longer than the polarization elimination time has passed before the time point T3, the SOC estimating unit 50 can derive the SOC in the OCV method at the time point T3 of the preparation start.

[0073] Furthermore, since the current integrated value is derived during the trip, at time point T2 , SOC estimating unit 50 can derive the SOC by current integration.

[0074] However, if the battery 20 is repeatedly charged and discharged, the battery 20 may deteriorate. If the battery 20 deteriorates, the full charge capacity of the battery 20 may decrease. The full charge capacity can be derived when the battery 20 is fully charged. When the battery 20 deteriorates, it is desirable to derive and update the full charge capacity.

[0075] However, if the full charge capacity decreases during the trip, the possibility of updating the full charge capacity during the trip is low. Therefore, in the current integration method, the SOC is estimated using the full charge capacity before the decrease. In this way, the SOC obtained by the current integration method at the end of the trip may be different from the actual SOC when the full charge capacity decreases. For example, Figure 2 In the example, if the full charge capacity decreases during the last trip between time point T1 and time point T2, the SOC value obtained by the current integration method at time point T2 may be different from the actual value.

[0076] In contrast, the SOC obtained from the OCV at time T3 when the current trip period starts is estimated without using the full charge capacity. Therefore, even if the full charge capacity decreases during the previous trip period, the decrease in the full charge capacity is reflected in the actual value.

[0077] In addition, if Figure 2 As shown, between time point T2 and time point T3, the current of battery 20 does not change. Therefore, ideally, the actual SOC at time point T2 and the actual SOC at time point T3 are the same value. In this way, the SOC obtained by the OCV method at time point T3 can be regarded as the SOC at time point T2.

[0078] Based on this, in the present embodiment, a concept of an SOC correction amount corresponding to the amount of deviation of the SOC between the end time point of a travel period and the start time point of the next travel period is introduced. Here, for the sake of convenience, the SOC estimated by the current integration method at the end of the travel period is sometimes referred to as the end SOC. The SOC estimated by the open circuit voltage method at the start of the next travel period of the travel period to which the end SOC belongs is sometimes referred to as the start SOC.

[0079] The SOC correction amount is derived from the difference between the above-mentioned end SOC and start SOC (SOC correction amount = end SOC - start SOC). Figure 2 In the example of , the SOC correction amount is the difference between the SOC obtained by the current integration method at time point T2 and the SOC obtained by the OCV method at time point T3. The SOC correction amount indicates the estimated error of the SOC corresponding to the trip period to which the SOC at the end belongs.

[0080] As described above, it is assumed that a reduction in the full charge capacity occurs during the trip between time point T1 and time point T2. In addition, as described above, the SOC obtained by the OCV method at time point T3 can be regarded as the SOC at time point T2. In this way, the SOC correction amount is equivalent to the SOC error between the SOC obtained by the current accumulation method without reflecting the reduction in the full charge capacity and the actual SOC obtained by the OCV method reflecting the reduction in the full charge capacity. In other words, the SOC correction amount is equivalent to the estimated error of the SOC caused by the reduction in the full charge capacity during the trip relative to the actual SOC.

[0081] In addition, the SOC correction amount at the time when the SOC correction amount is derived corresponds to the travel period before the travel period to which the time when the SOC correction amount is derived belongs.

[0082] In this embodiment, the concept of absolute current is also introduced. The absolute current is a value obtained by adding the accumulated value of the absolute value of the charging current in the battery 20 and the accumulated value of the absolute value of the discharging current in the battery 20. The absolute current is derived during the trip, and is derived for each trip. The absolute current shows how much the battery 20 is charged and how much it is discharged during one trip.

[0083] In the current integration method, the current integration value is integrated, for example, with the discharge current as a positive value and the charge current as a negative value. In contrast, for the absolute current amount, since both the charge current and the discharge current use absolute values, both the charge current and the discharge current are integrated as positive values.

[0084] In this embodiment, a concept of a correction index based on the SOC correction amount and the absolute current amount is also introduced. The correction index is derived by dividing the SOC correction amount corresponding to the trip period to which the SOC belongs at the end by the absolute current amount during the trip period to which the SOC belongs at the end (correction index = SOC correction amount / absolute current amount). The correction index corresponds to the trip period to which the SOC belongs at the end.

[0085] exist Figure 2 In the example of , the correction index is derived by dividing the SOC correction amount corresponding to the previous trip period derived at time point T3 as the current time point by the absolute current amount at time point T2 as the end time point of the previous trip period.

[0086] The correction index is an index obtained by removing the influence of charging and discharging during a trip period before the time point when the correction index is derived from an estimated error of the SOC.

[0087] In this embodiment, a concept of an absolute current amount cumulative value based on the absolute current amount is further introduced. The absolute current amount cumulative value is a value obtained by accumulating the absolute current amount over a plurality of travel periods from a predetermined reference time point. For example, when three travel periods have passed from a predetermined reference time point, the absolute current amount in the first travel period, the absolute current amount in the second travel period, and the absolute current amount in the third travel period are added to become the absolute current amount cumulative value.

[0088] As described above, the SOC correction amount indicates the estimated error of the SOC caused by the decrease in the full charge capacity, and therefore becomes a value related to the decrease in the full charge capacity. Based on this, the time point that becomes the predetermined reference in the above-mentioned absolute current amount integrated value is set as the time point when the full charge capacity of the battery 20 was last updated.

[0089] In this embodiment, the concept of plotting data based on the correction index and the absolute current amount integrated value is also introduced. The plotting data is data obtained by associating the correction index corresponding to the trip period to which the SOC at the end belongs and the absolute current amount integrated value until the trip period to which the SOC at the end belongs. The plotting data corresponds to the trip period to which the SOC at the end belongs, similarly to the associated correction index.

[0090] The drawing data at the time when the drawing data is generated corresponds to the travel period before the travel period to which the time when the drawing data is generated belongs.

[0091] exist Figure 2 In the example of , the plotting data corresponding to the last trip period is generated by associating the correction index corresponding to the last trip period derived at time point T3 as the current time point with the absolute current amount integrated value until the last trip period.

[0092] In the present embodiment, when the SOC estimating unit 50 determines that the polarization of the battery 20 is eliminated, it derives the SOC correction amount, derives the correction index, and generates the mapping data. The derived SOC correction amount, correction index, and mapping data are stored and accumulated in the storage device 26 .

[0093] In the derivation of the SOC correction amount, since the SOC derived by the OCV method is used, the SOC correction amount is derived only when the polarization of the battery 20 is eliminated. In addition, the SOC correction amount is used in the derivation of the correction index, and the correction index is used in the plotting data. Therefore, similar to the SOC correction amount, the correction index and the plotting data are derived only when the polarization of the battery 20 is eliminated. In other words, when the polarization of the battery 20 is not eliminated, the plotting data is not generated.

[0094] More specifically, the SOC estimating unit 50 may derive the SOC correction amount, the correction index, and the mapping data when both the predetermined first condition and the second condition are satisfied in addition to the polarization of the battery 20 being eliminated.

[0095] The predetermined first condition is to estimate the SOC by the open circuit voltage method at the beginning of the previous travel period to which the current time point belongs. Figure 2 In the example of , since the SOC is estimated by the OCV method at the time point T1 corresponding to the start time of the travel period before the current time point, the above-mentioned predetermined first condition is satisfied.

[0096] If the SOC is estimated by the OCV method at the beginning of the trip period, the estimated SOC is set as the initial value, so that the initial value of the SOC during the trip period can be obtained with high accuracy. Therefore, it is assumed that the SOC obtained by the current integration method during the trip period is estimated with relatively high accuracy. In this way, the SOC obtained by the current integration method estimated with relatively high accuracy is used as the SOC at the end of the trip period, so that the accuracy of the SOC correction amount can be improved.

[0097] The second predetermined condition is that the period from the end time point of the previous travel period to which the current time point belongs to until the travel period to which the current time point belongs is within the predetermined period. In the following, for the sake of convenience, the period from the end time point of the previous travel period to which the current time point belongs to until the travel period to which the current time point belongs is sometimes referred to as the preceding stop period.

[0098] The predetermined period in the predetermined second condition is set to a period longer than the polarization elimination time. The predetermined period is set to, for example, 7 days, but can be set to an appropriate period in consideration of the self-discharge of the battery 20 .

[0099] If the previous stop period is too long, the battery 20 will self-discharge. If self-discharge occurs, the actual SOC at time T3 may substantially change relative to the actual SOC at time T2. In this way, the SOC of the OCV method at time T3 may deviate from the actual SOC at time T2. As a result, the accuracy of the SOC correction amount may decrease.

[0100] Based on this, the SOC correction amount can be derived only when the previous stop period is not too long according to the predetermined second condition, thereby suppressing a decrease in the accuracy of the SOC correction amount. As a result, it is also possible to suppress a decrease in the accuracy of the correction index and the mapping data.

[0101] It should be noted that, here, an example is described in which the SOC correction amount, the correction index, and the plot data are derived when the three conditions of the battery 20 being polarized, the predetermined first condition, and the predetermined second condition are satisfied. However, when a decrease in the accuracy of the SOC correction amount and the like is permissible, the SOC estimating unit 50 may omit the predetermined first and second conditions and derive the SOC correction amount, the correction index, and the plot data when at least the battery 20 is polarized.

[0102] Figure 3 FIG. 2 is a diagram for explaining another example of the SOC estimation method and estimation timing. Figure 3 From time T1 to time T2, Figure 2 same. Figure 3 The next stroke period is shown to be ready to start at time point T4 after time point T2 and before the polarization elimination time. Figure 3 In the example, time point T4 is set as the current time point.

[0103] If the preparation is started before the polarization elimination time has passed, the polarization of the battery 20 may not be eliminated. Figure 3 As shown, it is inappropriate to estimate the SOC using the OCV method at the time point T4 which is the current time point.

[0104] Therefore, in the present embodiment, when it is determined that the polarization of the battery 20 has not been eliminated, the SOC estimating unit 50 derives an estimated value of a correction index corresponding to a travel period before the travel period to which the current time point belongs based on past mapping data. The SOC estimating unit 50 derives an initial value of the SOC for the travel period to which the current time point belongs based on the derived estimated value of the correction index. Hereinafter, the initial value of the SOC may be described as an SOC initial value.

[0105] More specifically, at the beginning of the current trip period, the polarization of the battery 20 has not been eliminated, so the SOC based on the OCV method cannot be properly derived, and the correction index corresponding to the previous trip period cannot be derived according to the definition formula. Therefore, the SOC estimating unit 50 estimates the correction index corresponding to the previous trip period based on the past mapping data.

[0106] By estimating the correction index corresponding to the last trip period, it is possible to know the extent of the estimated error of the SOC during the last trip period. Thus, if the absolute current amount during the last trip period is considered, the SOC at the end of the trip period that reflects the estimated error of the SOC during the last trip period can be known.

[0107] The SOC at the end of the previous trip period is ideally considered to be substantially the same as the SOC at the beginning of the current trip period. Therefore, by deriving the SOC at the end of the previous trip period based on the estimated value of the correction index corresponding to the previous trip period, the SOC at the beginning of the current trip period can be substantially derived. The SOC at the beginning of the current trip period derived in this way can be set as the initial value of the SOC in the current trip period.

[0108] Figure 4 FIG. 4 is a diagram for explaining the derivation of the initial SOC value based on the estimated value of the correction index. Figure 4 In FIG. 1 , the horizontal axis represents the absolute current amount integrated value from the time point that becomes a predetermined reference, specifically, the time point when the full charge capacity is updated. The vertical axis represents the correction index.

[0109] Figure 4 The black circle marks indicate past drawing data generated after the time point that becomes the predetermined reference. The drawing data Pm is the past drawing data closest to the current time point among the past drawing data. The drawing data Pn indicated by the white circle marks indicate the estimated value of the drawing data corresponding to the last travel period. It should be noted that from the perspective of the correction index and the estimated time of the drawing data, the white circle marks correspond to the current time point.

[0110] exist Figure 4 In the example, the absolute current amount integrated value xn is the absolute current amount integrated value until the previous stroke period, which is one stroke period before the stroke period to which the current time point belongs. The absolute current amount integrated value xm is the absolute current amount integrated value corresponding to the drawing data closest to the current time point among the past drawing data. The stroke period corresponding to the drawing data closest to the current time point among the past drawing data is, for example, the previous stroke period, which is the previous stroke period.

[0111] In addition, Figure 4 In the example, the difference absolute current integrated value α is the difference between the absolute current integrated value xn and the absolute current integrated value xm (α=xn-xm). In other words, the absolute current integrated value xn is the value obtained by adding the difference absolute current integrated value α to the absolute current integrated value xm (xn=xm+α).

[0112] For example, when the absolute current amount integrated value xm is greater than the absolute current amount integrated value during the previous trip, the difference absolute current amount integrated value α is equivalent to the absolute current amount during the previous trip. Therefore, the difference absolute current amount integrated value α is known at the time point of estimating the correction index. In addition, the absolute current amount integrated value xm is also known at the time point of estimating the correction index.

[0113] In addition, Figure 4 In the example of , the correction index yn is an estimated value of the correction index corresponding to the previous travel period.

[0114] SOC estimation unit 50 uses a plurality of past drawing data to derive an approximate expression for the plurality of past drawing data. The approximate expression is, for example, a linear function (y=ax+b). Figure 4 The line L1 is an example of a line illustrating an approximate formula.

[0115] The SOC estimating unit 50 substitutes a value “xm+α” obtained by adding the difference absolute current amount integrated value α to the absolute current amount integrated value xm into the approximate formula, and derives a correction index yn as an estimated value.

[0116] The SOC estimation unit 50 multiplies the correction index yn, which is the estimated value of the derived correction index, by the differential absolute current amount integrated value α, and derives it as a correction value (correction value = yn × α). Since the correction index includes information on the SOC correction amount, it includes information on the estimated error of the SOC caused by the reduction in the full charge capacity. Therefore, the correction value becomes a value that includes the influence of the reduction in the full charge capacity during the previous trip.

[0117] Here, for the sake of convenience, the travel period corresponding to the drawing data closest to the current time point in the past drawing data is sometimes referred to as the travel period of the previous drawing data. In addition, the SOC derived by the open circuit voltage method during the travel period of the previous drawing data is sometimes referred to as the previous SOC obtained by OCV.

[0118] The SOC estimation unit 50 adds the derived correction value to the end SOC derived at the end of the previous trip period and derives it as the SOC initial value (SOC initial value = last end SOC + correction value). As described above, since the correction value includes the effect of the decrease in the full charge capacity during the previous trip period, the SOC initial value becomes a value reflecting the effect of the decrease in the full charge capacity.

[0119] In this way, when it is determined that the polarization has not been eliminated, the initial value of the SOC is derived based on the estimated value of the correction index. Therefore, even if the polarization has not been eliminated, the initial value of the SOC can be derived with high accuracy.

[0120] exist Figure 4In the example described above, the travel period of the last drawing data is the travel period greater than the last travel period. However, the travel period of the last drawing data may be the travel period before the travel period greater than the last travel period. That is, during the period from the travel period of the last drawing data to the current travel period, there may be one or more travel periods in which the polarization is not eliminated and the drawing data cannot be generated.

[0121] If the number of travel periods during which drawing data cannot be generated increases from the travel period of the previous drawing data to the current travel period, the accuracy of the approximate formula may decrease.

[0122] Therefore, the SOC estimating unit 50 may determine whether the number of travel periods from the travel period of the last drawing data to the travel period before the travel period to which the current time point belongs is less than a predetermined number of times. Hereinafter, for convenience of explanation, the period from the travel period of the last drawing data to the travel period before the travel period to which the current time point belongs is sometimes referred to as the period from the travel period of the last drawing data to the last travel period.

[0123] The SOC estimating unit 50 may also derive the estimated value of the correction index and the initial value of the SOC based on the estimated value of the correction index when the number of travel periods from the travel period of the last plotted data to the last travel period is less than a predetermined number of times. The predetermined number of times here is set to, for example, 3 times, but can be set to any number based on the allowable degree of accuracy of the approximate formula.

[0124] Thus, by determining the number of travel periods from the travel period of the last drawing data to the last travel period, it is possible to suppress a decrease in the accuracy of the approximate formula. As a result, it is possible to suppress a decrease in the accuracy of the estimated value and the correction value of the correction index.

[0125] It should be noted that the determination condition of the number of travel periods from the travel period of the previous drawing data to the previous travel period may be omitted.

[0126] In addition, the upper limit value of the absolute value of the power allowed to be input to the battery 20 is sometimes referred to as the allowed input power. The upper limit value of the absolute value of the power allowed to be output from the battery 20 is sometimes referred to as the allowed output power. The allowed input power and the allowed output power are sometimes collectively referred to as the allowed power. That is, the allowed power refers to at least one of the allowed input power and the allowed output power.

[0127] Such allowable power is set for the battery 20. Here, the estimated value of SOC may be higher than the actual SOC by an amount of error. Thus, the allowable power is set to a relatively low value with a margin corresponding to the amount of error of SOC from the actual SOC.

[0128] In the present embodiment, SOC estimating unit 50 changes the value of the allowable electric power of battery 20 based on the correction index.

[0129] Figure 5 4 is a diagram illustrating the relationship between the correction index and the allowable power. Figure 5 The example shown in FIG. 1 is an allowable power map obtained by associating the correction index with the allowable power on a one-to-one basis. Figure 5 The numerical values ​​shown in the example are merely examples, and each numerical value of the allowable power map may be set to an arbitrary value in consideration of the type and specification of the battery 20 .

[0130] The permission level indicates the level of the permitted power. The permission level "0" corresponds to the initial setting value of the permitted power. Figure 5 As shown, the permission level and the permitted power are associated with each other in such a manner that the permitted power becomes larger as the permission level becomes larger.

[0131] As described above, as the correction index decreases, the estimation error of the SOC decreases. Based on this, in the allowable power map, the correction index and the allowable power are associated with each other so that the allowable power increases as the correction index decreases.

[0132] The SOC estimation unit 50 applies the derived correction index to the allowable power map to derive the allowable power. In this way, if the allowable power map is used to derive the allowable power, the allowable power can be made larger than the initial setting value of the allowable power as the correction index becomes smaller. In other words, the allowable power can be made more moderate than the initial setting value of the allowable power.

[0133] That is, in the present embodiment, the degree of the estimation error of the SOC can be understood from the correction index, and therefore the margin of the allowable electric power can be set to an appropriate value in accordance with the degree of the estimation error of the SOC.

[0134] Therefore, when deriving an estimated value of SOC such that the estimation error of SOC becomes small, it is possible to suppress the allowable electric power from being excessively limited. As a result, the drivability of the vehicle 1 can be improved by increasing the allowable electric power.

[0135] However, in the present embodiment, SOC estimating unit 50 may determine whether or not the full charge capacity needs to be updated based on a plurality of plotted data items calculated from a predetermined reference time point.

[0136] In the present embodiment, the SOC estimating unit 50 may determine whether an abnormality related to the derivation of the SOC has occurred based on a plurality of plotting data starting from a time point that serves as a predetermined reference.

[0137] Figure 6 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is an increasing tendency.

[0138] For example, an approximate expression of a plurality of plotted data may be derived, and if the slope of the approximate expression is a positive value greater than a predetermined value, it is determined that the change tendency of the correction index accompanying the change in the absolute current amount integrated value is an increasing tendency. It should be noted that the method of determining the change tendency is not limited to the method using the approximate expression, and for example, any known method such as determining the change tendency based on the moving average of a plurality of plotted data may be used.

[0139] When the correction index changes with the change in the absolute current amount integrated value and shows an increasing trend, it means that the full charge capacity of the battery 20 is gradually decreasing. It should be noted that the full charge capacity of the battery 20 is gradually decreasing, which is a normal deterioration pattern and not abnormal.

[0140] Therefore, when the correction index changes with the change of the absolute current amount integrated value and the latest correction index exceeds the predetermined upper limit threshold, the SOC estimation unit 50 determines that the full charge capacity needs to be updated. The predetermined upper limit threshold may also be set to an appropriate value in consideration of the update frequency of the full charge capacity, etc.

[0141] This makes it possible to appropriately detect a decrease in the full charge capacity, and request update of the full charge capacity at an appropriate timing and frequency when the full charge capacity decreases.

[0142] Furthermore, by including the condition that the change tendency of the correction index accompanying the change of the absolute current amount integrated value is an increasing tendency, it is possible to avoid situations where a full charge capacity is needlessly requested to be updated due to an outlier such as a case where the correction index accidentally exceeds an upper limit threshold.

[0143] The condition that the correction index exceeds the upper limit threshold is not limited to the latest correction index, and the condition may be satisfied when the correction index exceeds the upper limit threshold in at least one of a plurality of drawing data from a predetermined reference time.

[0144] When it is determined that the fully charged capacity needs to be updated, the SOC estimating unit 50, for example, turns on an update request flag indicating that the fully charged capacity needs to be updated. Furthermore, when the conditions for deriving the fully charged capacity are satisfied, such as when the battery 20 is fully charged, if the update request flag is turned on, the SOC estimating unit 50 derives and updates the fully charged capacity.

[0145] Furthermore, when preparation starts after the full charge capacity is updated, SOC estimating unit 50 resets the absolute current amount integrated value to the initial value.

[0146] Furthermore, when the change tendency of the correction index accompanying the change of the absolute current amount integrated value is an increasing tendency, it is assumed that the SOC is estimated appropriately, and therefore the SOC estimating unit 50 determines that there is no abnormality related to the derivation of the SOC.

[0147] Figure 7 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is a decreasing tendency.

[0148] For example, an approximate expression may be derived for a plurality of plotted data, and if the slope of the approximate expression is a negative value equal to or smaller than a predetermined value, it may be determined that the change tendency of the correction index accompanying the change in the absolute current amount integrated value is a decreasing tendency.

[0149] When the correction index changes with the change of the absolute current amount cumulative value and shows a decreasing trend, it means that the fully charged capacity has increased from the perspective of the fully charged capacity. Normally, the fully charged capacity will hardly increase. Therefore, when the correction index shows a decreasing trend, it is assumed that some abnormality has occurred in the process of estimating the SOC.

[0150] Therefore, the SOC estimation unit 50 may determine that an abnormality related to the derivation of the SOC has occurred when the change trend of the correction index with the change of the absolute current amount integrated value is a decreasing trend and the latest correction index is lower than a predetermined lower limit threshold. The lower limit threshold may also be set to an arbitrary value taking into account the normal fluctuation range of the correction index.

[0151] When it is determined that an abnormality has occurred, the fact may be notified, for example, through an error display, etc. Also, when it is determined that an abnormality has occurred, a predetermined restriction may be imposed on the control of the vehicle 1, for example, by making the allowable power lower than an initial setting value.

[0152] This makes it possible to appropriately detect that the SOC is not estimated appropriately. As a result, it is possible to appropriately handle an abnormality related to the derivation of the SOC.

[0153] Furthermore, by including the condition that the change trend of the correction index accompanying the change of the absolute current amount integrated value is a decreasing trend, it is possible to avoid a situation where an abnormality is erroneously determined to have occurred due to an outlier such as the correction index accidentally exceeding the lower limit threshold.

[0154] It should be noted that the condition that the correction index is lower than the lower limit threshold is not limited to the latest correction index, and the condition may be satisfied when the correction index is lower than the lower limit threshold in at least one of a plurality of drawing data from a predetermined reference time.

[0155] If the change trend of the correction index accompanying the change of the absolute current amount integrated value is a decreasing trend, it is assumed that an abnormality related to the derivation of the SOC has occurred, and therefore the SOC estimating unit 50 does not request updating of the full charge capacity.

[0156] Figure 8 This is a diagram showing an example of a plurality of plotted data in a case where the change tendency of the correction index accompanying the change of the absolute current amount integrated value is substantially constant.

[0157] For example, an approximate expression may be derived for a plurality of plotted data, and if the slope of the approximate expression is a positive value smaller than a predetermined value and a negative value smaller than a predetermined value, it may be determined that the change tendency of the correction index with the change of the absolute current amount integrated value is substantially constant.

[0158] If the change tendency of the correction index accompanying the change of the absolute current amount integrated value is substantially constant, it is assumed that the full charge capacity is hardly reduced.

[0159] Therefore, if the change tendency of the correction index accompanying the change of the absolute current amount integrated value is substantially constant, the SOC estimation unit 50 does not request to update the full charge capacity. For example, the SOC estimation unit 50 turns off the update request flag. This can suppress unnecessary updates of the full charge capacity.

[0160] Furthermore, if the change tendency of the correction index accompanying the change of the absolute current amount integrated value is substantially constant, it is assumed that the SOC is estimated appropriately, and therefore the SOC estimating unit 50 determines that there is no abnormality related to the derivation of the SOC.

[0161] Fig. 9 The flowchart is for explaining the flow of the operation of the SOC estimating unit 50. The SOC estimating unit 50 starts in response to the vehicle 1 preparing to start. Fig. 9 A series of processing.

[0162] When the vehicle 1 is ready to start, the SOC estimating unit 50 reads various data necessary for estimating the SOC from the storage device 26 or the memory 42 (S10). The read data include, for example, the absolute current amount during the last trip and the absolute current amount integrated value until the last trip.

[0163] Next, the SOC estimating unit 50 executes an SOC initial value deriving process ( S11 ) for deriving an SOC initial value during the current trip. The SOC initial value deriving process ( S11 ) will be described in detail later.

[0164] Next, the SOC estimation unit 50 determines whether Fig. 9 After a series of processing, it is determined whether the full charge capacity has been updated during the period up to the current time point (S12).

[0165] If it is determined that the full charge capacity has been updated (Yes in S12), SOC estimation unit 50 resets the absolute current amount integrated value to the initial value (S13), and ends the process. Fig. 9 The initial value is, for example, zero. Thus, the absolute current amount integrated value is re-integrated from the current trip period.

[0166] If it is determined that the full charge capacity has not been updated (No in S12), SOC estimating unit 50 terminates the process. Fig. 9 A series of processing.

[0167] Fig.10 Yes Fig. 9 This is a flowchart for explaining the flow of processing that SOC estimating unit 50 periodically repeatedly executes after the processing until vehicle 1 becomes ready.

[0168] When the scheduled execution time arrives, the SOC estimation unit 50 derives the current integrated value during the current trip based on the current detected by the current sensor 24 (S20). Next, the SOC estimation unit 50 derives the absolute current amount during the current trip based on the current detected by the current sensor 24 (S21). The SOC estimation unit 50 stores the derived current integrated value and absolute current amount in the storage device 26 (S22). It should be noted that since the execution is repeated periodically, Fig.10 Therefore, the current accumulation value and absolute current amount are processed each time Fig.10 are updated to the latest values ​​during processing.

[0169] Next, SOC estimation unit 50 determines whether vehicle 1 is ready (S23). If determined to be ready (Yes in S23), SOC estimation unit 50 estimates the SOC at the end of the current trip period by current integration based on the current integrated value derived in step S20 (S24).

[0170] Next, the SOC estimation unit 50 derives the absolute current amount integrated value based on the absolute current amount derived in step S21 (S25). For example, the SOC estimation unit 50 adds the absolute current amount during the current trip to the absolute charge amount integrated value until the previous trip, and derives the absolute current amount integrated value until the current trip. The SOC estimation unit 50 stores the SOC and the absolute current amount integrated value at the end in the storage device 26 (S26), and ends. Fig.10 A series of processing.

[0171] If it is determined that the vehicle is not ready (No in S23), SOC estimation unit 50 ends the operation. Fig.10 A series of processing.

[0172] Fig.11 1 is a flowchart for explaining the flow of the SOC initial value derivation process (S11). When the SOC initial value derivation process (S11) is started, the SOC estimation unit 50 determines whether the polarization of the battery 20 has been eliminated (S30). For example, if the elapsed time from the time point of the preparation during the previous trip is greater than the polarization elimination time, the SOC estimation unit 50 may determine that the polarization has been eliminated.

[0173] When it is determined that the polarization has been eliminated (Yes in S30), the SOC estimating unit 50 obtains the OCV detected by the voltage sensor 22, derives the SOC by the OCV method, and sets the derived SOC as the initial SOC value for the current trip period (S31). The initial SOC value derived in step S31 is equivalent to the starting SOC estimated by the OCV method at the beginning of the current trip period.

[0174] Next, the SOC estimating unit 50 determines whether the SOC initial value has been derived from the OCV in the SOC initial value derivation process ( S11 ) at the start of the previous travel period, ie, at the previous preparation start ( S32 ).

[0175] When it is determined that the SOC initial value was derived from the OCV at the start of the previous travel period (YES in S32 ), SOC estimating unit 50 determines whether the previous stop period is within a predetermined period ( S33 ).

[0176] When it is determined that the previous stop period is within the predetermined period (Yes in S33), the SOC estimating unit 50 derives the SOC correction amount corresponding to the previous trip period (S34). For example, the SOC estimating unit 50 subtracts the SOC initial value derived in step S31 from the end SOC estimated by the current integration method at the end of the previous trip period, thereby deriving the SOC correction amount.

[0177] Next, the SOC estimating unit 50 divides the SOC correction amount derived in step S34 by the absolute current amount during the previous trip, thereby deriving a correction index corresponding to the previous trip period ( S35 ).

[0178] Next, the SOC estimating unit 50 associates the correction index derived in step S35 with the absolute current amount integrated value until the last trip period, and generates mapping data corresponding to the last trip period ( S36 ).

[0179] Next, the SOC estimating unit 50 stores the derived SOC correction amount, correction index, and mapping data in the storage device 26 ( S37 ).

[0180] Next, SOC estimation unit 50 sets the allowable power of battery 20 (S38) based on the correction index derived in step S34 and the allowable power map stored in memory 42. The smaller the correction index derived in step S34, the larger the allowable power is set by SOC estimation unit 50.

[0181] Next, the SOC estimating unit 50 performs a full charge capacity update determination process (S39) including a process for determining whether the full charge capacity needs to be updated, and ends the SOC initial value derivation process (S11). The full charge capacity update determination process (S39) will be described in detail later.

[0182] In step S32 , when it is determined that the SOC initial value has not been derived from the OCV at the start of the previous travel period (NO in S32 ), SOC estimating unit 50 ends the SOC initial value deriving process ( S11 ).

[0183] In step S33 , when it is determined that the previous stop period exceeds the predetermined period (NO in S33 ), SOC estimating unit 50 ends the SOC initial value deriving process ( S11 ).

[0184] In step S30 , when it is determined that polarization has not been eliminated (No in S30 ), SOC estimating unit 50 determines whether the number of travel periods from the travel period of the previous mapping data to the previous travel period is equal to or greater than a predetermined number ( S40 ).

[0185] When it is determined that the number of travel periods from the travel period of the last plotted data to the last travel period is greater than the predetermined number of times (Yes in S40), the SOC estimating unit 50 sets the end SOC derived at the end of the last travel period as the SOC initial value for the current travel period (S41). Then, the SOC estimating unit 50 ends the SOC initial value derivation process (S11).

[0186] When it is determined that the number of travel periods from the travel period of the last plotted data to the last travel period is less than the predetermined number (No in S40), SOC estimating unit 50 performs correction value deriving processing (S42) for deriving a correction value. Correction value deriving processing (S42) will be described in detail later.

[0187] Next, the SOC estimating unit 50 adds the correction value derived by the correction value deriving process (S42) to the end SOC derived at the end of the previous trip period, and sets the result as the SOC initial value for the current trip period (S43). Then, the SOC estimating unit 50 ends the SOC initial value deriving process (S11).

[0188] Fig.12 2 is a flowchart for explaining the flow of the full charge capacity update determination process (S39). When the full charge capacity update determination process (S39) is started, the SOC estimation unit 50 reads past drawing data after the full charge capacity is updated from the storage device 26 (S50).

[0189] Next, the SOC estimating unit 50 determines whether the change trend of the correction index accompanying the change of the absolute current amount integrated value in the past mapping data is an increasing trend ( S51 ).

[0190] When it is determined that the change trend of the correction index accompanying the change in the absolute current amount integrated value is an increasing trend (YES in S51 ), SOC estimating unit 50 determines whether the latest correction index exceeds an upper limit threshold value ( S52 ).

[0191] When it is determined that the latest correction index exceeds the upper limit threshold (Yes in S51), the SOC estimation unit 50 sets the update request flag for requesting update of the full charge capacity to an on state (S53). Thereby, when the battery 20 is charged to full charge and the conditions for deriving the full charge capacity are satisfied, the full charge capacity is updated because the update request flag is in the on state. It should be noted that if the full charge capacity is updated, the update request flag is set to the off state.

[0192] After step S53, SOC estimating unit 50 determines that there is no abnormality related to derivation of SOC (S54), and ends the full charge capacity update determination process (S39).

[0193] In step S52, when it is determined that the latest correction index does not exceed the upper limit threshold (No in S51), SOC estimation unit 50 turns off the update request flag (S55). Thus, the full charge capacity is not updated.

[0194] After step S55 , SOC estimating unit 50 determines that there is no abnormality related to derivation of SOC ( S54 ), and ends the full charge capacity update determination process ( S39 ).

[0195] In step S51 , when it is determined that the trend is not an increasing trend (No in S51 ), SOC estimating unit 50 determines whether the change trend of the correction index accompanying the change in the absolute current amount integrated value is a decreasing trend ( S57 ).

[0196] When it is determined that the change trend of the correction index accompanying the change in the absolute current amount integrated value is a decreasing trend (YES in S57 ), SOC estimating unit 50 determines whether the latest correction index is lower than a lower limit threshold value ( S58 ).

[0197] When it is determined that the latest correction index is lower than the lower limit threshold (Yes in S58 ), SOC estimating unit 50 turns the update request flag off ( S59 ).

[0198] After step S59, the SOC estimation unit 50 determines that there is an abnormality related to the derivation of the SOC (S60), notifies that there is an abnormality (S61), and ends the full charge capacity update determination process (S39). It should be noted that when it is determined that there is an abnormality related to the derivation of the SOC, the SOC estimation unit 50 may also impose predetermined restrictions on the control of the vehicle 1.

[0199] In step S57, if it is determined that there is no decreasing trend (No in S57), the SOC estimating unit 50 turns off the update instruction flag (S55). The SOC estimating unit 50 determines that there is no abnormality related to the derivation of SOC (S54), and ends the full charge capacity update determination process (S39).

[0200] In step S58, when it is determined that the latest correction index is not lower than the lower limit threshold (No in S58), the SOC estimation unit 50 turns the update indication flag off (S55). The SOC estimation unit 50 determines that there is no abnormality related to the derivation of the SOC (S54), and ends the full charge capacity update determination process (S39).

[0201] Fig.13 1 is a flowchart for explaining the flow of the correction value derivation process (S42). When the correction value derivation process (S42) is started, the SOC estimation unit 50 reads past drawing data after the time point when the full charge capacity is updated from the storage device 26 (S70). The SOC estimation unit 50 derives an approximate formula for the past drawing data (S71).

[0202] The SOC estimation unit 50 substitutes the value obtained by adding the absolute current accumulation value to the difference absolute current accumulation value during the trip period until the last plotting data into the approximate formula to derive the estimated value of the correction index (S72). The SOC estimation unit 50 multiplies the estimated value of the correction index by the difference absolute current accumulation value to derive the correction value (S73), and ends the correction value deriving process (S42).

[0203] As described above, the SOC estimating unit 50 of the SOC estimating device 10 of the present embodiment generates mapping data in which the correction index corresponding to the trip period to which the SOC at the end belongs is associated with the absolute current integrated value, which is the current integrated value until the trip period to which the SOC at the end belongs. When it is determined that the polarization of the battery 20 has not been eliminated, the SOC estimating unit 50 derives an estimated value of the correction index corresponding to the trip period before the trip period to which the current time point belongs based on the past mapping data. The SOC estimating unit 50 derives the initial value of the SOC for the trip period to which the current time point belongs based on the estimated value of the correction index.

[0204] The correction index and the plotted data in this embodiment include information on the estimated error of the SOC relative to the actual SOC caused by the reduction in the full charge capacity during the trip. Therefore, in this embodiment, by deriving the SOC initial value based on the estimated value of the correction index, it is possible to derive the SOC initial value in which the influence of the reduction in the full charge capacity during the previous trip is reflected in the SOC initial value during this trip.

[0205] Therefore, according to the SOC estimation device 10 of the present embodiment, even when the polarization of the battery 20 is not eliminated, it is possible to estimate an appropriate initial value of the SOC. As a result, according to the SOC estimation device 10 of the present embodiment, it is possible to improve the estimation accuracy of the SOC obtained by the current integration method using the initial value of the SOC.

[0206] Above, the embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is certainly not limited to the embodiments. As long as one is skilled in the art, various variations or modifications can be obviously thought of within the scope described in the claims, and it should be understood that these variations or modifications also belong to the technical scope of the present invention.

Claims

1. A SOC estimation device, It is characterized in that have: A battery, which is mounted on a vehicle; and a control device that estimates the SOC of the battery, The control device comprises: one or more processors; and one or more memories connected to the processor, The period from the start of the vehicle preparation until it is ready is the travel period. The processor performs the following processing, which includes: deriving a difference between an end SOC and a start SOC as an SOC correction amount indicating an estimated error of the SOC corresponding to the trip period to which the end SOC belongs, the end SOC being the SOC estimated by the current integration method at the end of the trip period, and the start SOC being the SOC estimated by the open circuit voltage method at the start of the trip period next to the trip period to which the end SOC belongs; deriving an absolute current amount during the trip, the absolute current amount being a value obtained by adding an integrated value of absolute values ​​of charging currents in the battery and an integrated value of absolute values ​​of discharging currents in the battery; The SOC correction amount corresponding to the trip period to which the end SOC belongs is divided by the absolute current amount in the trip period to which the end SOC belongs, and is derived as a correction index corresponding to the trip period to which the end SOC belongs; deriving an absolute current amount integrated value, the absolute current amount integrated value being a value obtained by integrating the absolute current amount over a plurality of the trip periods from a time point that becomes a predetermined reference; generating plotting data in which the correction index corresponding to the trip period to which the end SOC belongs is associated with the absolute current amount integrated value until the trip period to which the end SOC belongs; At the beginning of the trip period, determining whether polarization of the battery is eliminated; If it is determined that the polarization of the battery has not been eliminated, deriving an estimated value of the correction index corresponding to the travel period before the travel period to which the current time point belongs based on the past mapping data; and Based on the estimated value of the correction index, an initial value of the SOC in the travel period to which the current time point belongs is derived.

2. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: multiplying a differential absolute current amount integrated value by the derived estimated value of the correction index, the differential absolute current amount integrated value being a difference between the absolute current amount integrated value until the stroke period before the stroke period to which the current time point belongs and the absolute current amount integrated value corresponding to the drawing data closest to the current time point among the past drawing data, and deriving the value as a correction value; and The correction value derived is added to the end SOC derived at the end of the travel period before the travel period to which the current time point belongs, and the resultant is derived as an initial value of the SOC.

3. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: When the number of travel periods from the travel period corresponding to the drawing data closest to the current time point among the past drawing data until the travel period before the travel period to which the current time point belongs is less than a predetermined number, a process of deriving an estimated value of the correction index and a process of deriving an initial value of the SOC based on the estimated value of the correction index are performed.

4. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: If it is determined that the polarization of the battery has been eliminated in the determination of whether the polarization of the battery has been eliminated, a process of deriving the SOC correction amount, a process of deriving the correction index, and a process of generating the drawing data are performed.

5. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: When it is determined that the polarization of the battery is eliminated and the SOC is estimated by the open circuit voltage method at the beginning of the trip period before the trip period to which the current time point belongs, and the period from the end time point of the trip period before the trip period to which the current time point belongs to the end of the trip period is within a predetermined period, the process of deriving the SOC correction amount, the process of deriving the correction index, and the process of generating the drawing data are performed.

6. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: Whether or not the full charge capacity of the battery needs to be updated is determined based on the plurality of drawing data counted from the predetermined reference time point.

7. The SOC estimating device according to claim 6, It is characterized in that The processor performs the following processing, which includes: When, among the plurality of drawing data calculated from the time point that becomes the predetermined reference, the change tendency of the correction index accompanying the change of the absolute current amount integrated value is an increasing tendency and the latest correction index exceeds a predetermined upper limit threshold, it is determined that the full charge capacity of the battery needs to be updated.

8. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: Whether or not an abnormality related to derivation of the SOC has occurred is determined based on the plurality of drawing data counted from a time point that serves as the predetermined reference.

9. The SOC estimating device according to claim 8, It is characterized in that The processor performs the following processing, which includes: When, among the plurality of drawing data calculated from the time point that becomes the predetermined reference, the change trend of the correction index accompanying the change of the absolute current amount integrated value is a decreasing trend and the latest correction index is lower than a predetermined lower limit threshold, it is determined that an abnormality related to the derivation of the SOC has occurred.

10. The SOC estimating device according to claim 1, It is characterized in that at least one of an upper limit value of an absolute value of electric power allowed to be input to the battery and an upper limit value of an absolute value of electric power allowed to be output from the battery is the allowed electric power, The processor performs the following processing, which includes: Based on the derived correction index, the value of the allowable electric power is changed so that the value of the allowable electric power increases as the correction index decreases.

11. The SOC estimating device according to claim 1, It is characterized in that The processor performs the following processing, which includes: determining whether the full charge capacity in the battery is updated; and When it is determined that the full charge capacity of the battery has been updated, the absolute current amount integrated value is reset to an initial value.

12. The SOC estimating device according to claim 1, It is characterized in that The predetermined reference time point is a time point at which the full charge capacity of the battery is updated.

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