Secondary battery full charge capacity estimation method and secondary battery full charge capacity estimation device

Abstract

To provide a secondary battery full charge capacity estimation method capable of easily estimating the full charge capacity of a secondary battery.SOLUTION: The estimation method includes the following steps: measuring the current [Ah] of a lithium-ion secondary battery as the object; estimating SOC [%]; estimating voltage [V] from a battery model; and storing a voltage error [V] (S3). The estimation method further includes, after storing the data more than the specified value (S4: YES), calculating approximate straight line from the estimated SOC and the voltage error (S5); determining whether the estimated full charge capacity of the secondary battery is greater than or less than the true value from the inclination (S6); and correcting the estimation of parameters closely related to full charge capacity [Ah] based on the inclination (S7, S8).SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method and device for estimating the full charge capacity of a secondary battery, and more particularly to a method and device for estimating the full charge capacity of a secondary battery that can easily estimate the full charge capacity of a secondary battery. [Background technology]

[0002] Secondary batteries, such as ternary lithium-ion secondary batteries, have a high voltage and a large full charge capacity, making them suitable for use in driving electric vehicles and the like. In such lithium-ion secondary batteries, degradation can occur with use, and the full charge capacity (FCC·Full Charge Capacity) [Ah] can decrease. When the full charge capacity decreases, deviations occur in the estimation of the SOC (State of Charge) [%], etc. Therefore, by correctly estimating the full charge capacity [Ah], it is possible to control the battery so that it can fully demonstrate its performance and suppress deterioration.

[0003] Therefore, in the invention described in Patent Document 1, the full charge capacity [Ah] is estimated from the curve of SOC [%] and OCV (Open Circuit Voltage) [V] and the accumulated battery current [Ah]. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-178156 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the storage battery described in Patent Document 1, the full charge capacity [Ah] is estimated using a current integration method, which integrates noise from the current sensor. As a result, the full charge capacity [Ah] may not be accurately estimated, making it difficult to accurately estimate the full charge capacity [Ah].

[0006] Therefore, the problem to be solved by the method and device for estimating full charge capacity of a secondary battery of the present invention is to easily estimate the full charge capacity of a secondary battery. [Means for solving the problem]

[0007] In order to solve the above problems, the method for estimating the full charge capacity of a secondary battery of the present invention includes: EST Steps for estimating SOC [%] and estimated voltage E EST A step of estimating a voltage [V] and a step of measuring the voltage E DATA A voltage measurement step of measuring [V] and estimating the estimated voltage E EST The measured voltage E measured at the same time as [V] DATA A step of calculating a voltage error ΔE [V] which is a voltage difference between the voltage error ΔE [V] and the voltage error ΔE [V] at the same time; EST a step of storing an estimated SOC·voltage error, in which a plurality of pairs of values ​​of ΔE[V] and ΔE[V] are stored at different times; and a step of storing the estimated SOC·voltage error, in which a plurality of pairs of values ​​of ΔE[V] and ΔE[V] are stored at different times; EST [%] shows the relationship with the straight line ΔE=a(S EST )+b (where a is the slope and b is the intercept) of the line calculated; and estimating the full charge capacity F [Ah] based on the slope a of the line calculated in the line calculation step. EST and the true value of the full charge capacity F [Ah] F TRUE and a full charge capacity estimation deviation direction calculation step for calculating a full charge capacity estimation deviation direction ΔF that indicates a magnitude relationship with respect to the full charge capacity estimation deviation direction ΔF.

[0008] The SOC estimation step includes a current measurement step of measuring a current I [A] flowing through the secondary battery, and a step of estimating a voltage E from the current I [A] and an internal resistance R [mΩ] of a battery model of the secondary battery. EST A voltage estimation step of estimating the voltage [V] and an estimated SOC of the secondary battery S estimated from the current ΣI [Ah] which is the integrated current I [A]. EST [%] may be estimated.

[0009] Further, based on the full charge capacity estimation deviation direction ΔF calculated in the step of calculating the full charge capacity estimation deviation direction, the straight line ΔE=a(S EST ) + b so that the slope a of the equation becomes horizontal. EST The method may further include a step of correcting the estimated full charge capacity value [Ah].

[0010] Alternatively, the straight line ΔE=a(S EST The method may further include a parameter correction step of correcting a parameter used to control the secondary battery so that a gradient a of (a)+b becomes horizontal. In this case, the parameter correction step may include a negative electrode average Li-ion concentration [%] correction step of correcting an estimated value of the negative electrode average Li-ion concentration [%] as the parameter. The negative electrode average Li-ion concentration [%] correction step may also include a procedure of correcting the estimated value of the negative electrode average Li-ion concentration [%] by a constant value in a direction in which the deviation of the estimation of the full charge capacity estimation deviation direction ΔF becomes smaller until the gradient a is reversed from positive to negative.

[0011] In the step of estimating the SOC, the estimated SOC of the secondary battery, S ESTThe method may further include a step of SOC determination in which the method for estimating the full charge capacity of a secondary battery is executed only when the value of SOC [%] is within a preset SOC range. This method can also be suitably implemented when the secondary battery is a lithium-ion secondary battery. In this case, the secondary battery is a ternary lithium-ion secondary battery, and the preset SOC range may be set within a range of 40[%] or more and 70[%] or less.

[0012] In addition, in the secondary battery full charge capacity estimation device of the present invention, the SOC of the target secondary battery, S EST The SOC estimation section estimates the voltage E EST A voltage estimation unit that estimates the voltage E of the secondary battery [V] DATA A voltage measuring unit that measures the voltage E EST [V] and the voltage E DATA [V], which is the difference between the voltage error ΔE [V] and the EST a voltage error ΔE[V] derived from the plurality of value pairs stored at different times in the SOC·voltage error storage unit and the ... EST [%] shows the relationship with the straight line ΔE=a(S EST )+b (where a is the slope and b is the intercept), and an estimated value F of the full charge capacity F [Ah] based on the slope a of the line derived by the line calculation unit. EST [Ah] and the true value of full charge capacity F[Ah] TRUE The present invention is characterized in that it includes a full charge capacity estimation deviation direction calculation unit that calculates a full charge capacity estimation deviation direction ΔF that indicates a magnitude relationship with [Ah].

[0013] The SOC estimation unit includes a current measurement unit that measures a current I [A] flowing through the secondary battery, and a voltage E from the current I [A] and an internal resistance R [mΩ] of a battery model of the secondary battery. EST a voltage estimation unit for estimating a current ΣI [Ah] that is an integrated current I [A], and a voltage estimation unit for estimating a SOC of the secondary battery, S EST [%] may be estimated.

[0014] In this case, the straight line ΔE=a(S EST ) + b is adjusted so that the slope a of the equation becomes horizontal. EST A full charge capacity estimate correction unit that corrects [Ah] may be provided.

[0015] Alternatively, based on the full charge capacity estimation deviation direction ΔF calculated by the full charge capacity estimation deviation direction calculation unit, the straight line ΔE=a(S EST The present invention may further include a parameter correction unit that corrects parameters used to control the secondary battery so that a gradient a of the function a+b becomes horizontal. Effect of the Invention

[0016] According to the method and device for estimating full charge capacity of a secondary battery of the present invention, the full charge capacity of a secondary battery can be easily estimated. [Brief description of the drawings]

[0017] [Figure 1] 13 is a graph showing the change in voltage [V] relative to the change in capacity [Ah] when the estimated value FEST<the true value FTRUE, when the estimated value FEST=the true value FTRUE, and when the estimated value FEST<the true value FTRUE. [Diagram 2] 13 is a graph showing the overall relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value FEST of the full charge capacity is greater than the true value FTRUE. [Diagram 3] 11 is a graph showing the overall relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value FEST of the full charge capacity is smaller than the true value FTRUE. [Figure 4] 13 is a graph showing an estimated range of the relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value FEST of the full charge capacity is smaller than the true value FTRUE. [Diagram 5] 13 is a graph showing an estimated interval of the relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value FEST of the full charge capacity is greater than the true value FTRUE. [Figure 6] 1 is a perspective view showing the outline of the external configuration of a lithium-ion secondary battery according to an embodiment of the present invention; [Figure 7] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body. [Figure 8] FIG. 1 is a block diagram showing an example of the configuration of a vehicle that uses a lithium ion secondary battery in an implementation stage. [Figure 9] 2 is a block diagram showing the details of the configuration of a memory of an ECU of the full-charge capacity estimation device according to the embodiment; FIG. [Figure 10] 3 is a flowchart showing an example of a procedure of a method for estimating a full charge capacity of a secondary battery according to the present embodiment. [Figure 11] FIG. 2 is a diagram showing an equivalent circuit of the lithium ion secondary battery of the present embodiment. [Figure 12] (a) Graph showing estimated voltage EEST [V] versus measured voltage EDATA [V] over time. (b) Graph showing voltage error ΔE [V] over time. (c) Graph showing estimated SOC SEST [%] versus true SOC value STRUE [%] over time. (d) Graph showing SOC error ΔS [%] over time. (e) Graph showing estimated full charge capacity FEST [Ah] versus true full charge capacity FTRUE [Ah] over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The method and device for estimating the full charge capacity of a secondary battery of the present invention will be described below with reference to Figs. 1 to 12, taking as an example a device for estimating the full charge capacity of a lithium ion secondary battery 10 mounted on a vehicle.

[0019] <Principle of this embodiment> Figure 1 shows the estimated F EST is the true value F TRUE If less than 、 Estimated value F EST is the true value F TRUE is equal to 、 Estimated value F EST is the true value F TRUEThis is a graph showing the change in voltage [V] versus the change in capacity [Ah], for cases where the capacity is larger than 1A.

[0020] In the case of the lithium-ion secondary battery 10, the relationship between the actual capacity [Ah] and the voltage [V] is shown in graph L. 4 The true value of the full charge capacity F is shown by F TRUE [Ah]. The estimated full charge capacity F is F EST [Ah] is the true value of the full charge capacity F TRUE If the estimated value is lower than [Ah], graph L 3 On the other hand, the estimated full charge capacity F EST [Ah] is the true value of the full charge capacity F TRUE If the estimated value is higher than [Ah], graph L 5 The slope shown in the graph becomes larger. Then, the magnitude of the voltage [V] fluctuation due to the error in the estimation of the full charge capacity F is 3 >Graph L 4 >Graph L 5 The order is as follows.

[0021] From this characteristic, the estimated full charge capacity F is EST [Ah] is the true value of the full charge capacity F TRUE If the estimated full charge capacity F is smaller than [Ah], the voltage error ΔE [V] will shift larger as the capacity, i.e., the SOC, increases. Conversely, the estimated full charge capacity F EST [Ah] is the true value of the full charge capacity F TRUE If the estimated capacity is greater than [Ah], the voltage error ΔE [V] will shift smaller as the capacity, i.e., SOC, increases.

[0022] Figure 4 shows the estimated full charge capacity F EST <True value F TRUE 5 is a graph showing an estimated range of the relationship between the estimated SOC [%] and the voltage error ΔE [V] in the case of EST >True value F TRUE 13 is a graph showing an estimated interval of the relationship between the estimated SOC: [%] and the voltage error ΔE [V] in the case of

[0023] <Estimation of full charge capacity F> As shown in Figure 4, the estimated SOC in the estimation section, S EST When [%] changes significantly, the voltage error ΔE changes slightly. In other words, the estimated value F of the full charge capacity F EST <True value F TRUE On the other hand, as shown in Figure 5, the estimated SOC in the estimation section, S EST When the [%] changes significantly, the voltage error ΔE changes significantly. In other words, the estimated value F of the full charge capacity F EST >True value F TRUE It can be seen that.

[0024] Therefore, the graph L of the straight line derived from the plot points in Figure 4 1 , or the graph L of the straight line derived from the plotted points in Fig. 5 2 In both cases, the voltage error ΔE can be expressed as a(Sest)+b (where a is the slope and b is the intercept). 1 Or L 2 If the slope is a < 0 and the line slopes downward to the right, the estimated value F of the full charge capacity F is EST >True value F TRUE In addition, if the slope is a>0 and the line slopes upward to the right, the estimated value F of the full charge capacity F is EST <True value F TRUE It can be seen that.

[0025] <Fill-charge capacity estimate based on slope a F EST Correction of > In addition, in the judgment based on the slope a, the true value F TRUE For the estimated value F EST It is possible to estimate whether F is too large or too small, but the true value F TRUE The estimated value F EST Of course, it is not possible to immediately calculate the true value of the full charge capacity F. TRUE Therefore, the inclination a is set as the "full charge capacity estimation deviation direction ΔF" and the estimated full charge capacity F EST is used as the direction of the correction value.

[0026] In other words, if the slope a>0, the estimated value F of the full charge capacity F EST However, since the direction of the correction is clear but the amount of correction is unknown, the slope a is increased by a fixed value and the positive or negative of the slope a is judged again. Then, the correction is repeated until the slope a approaches 0. In addition, if the slope a<0, the estimated value F of the full charge capacity F is calculated in the same manner. EST Make small corrections.

[0027] <Parameter modification> The purpose of the full charge capacity estimation in this embodiment is not to obtain an accurate absolute value of the full charge capacity F [Ah] itself, but to appropriately control the target lithium ion secondary battery 10. Therefore, for example, by accurately estimating the "average negative electrode Li ion concentration", which is a parameter that affects the full charge capacity F [Ah], the target lithium ion secondary battery 10 can be appropriately controlled. Here, it is known that there is a relationship of full charge capacity F [Ah] ∝ "average negative electrode Li ion concentration". Therefore, for the "average negative electrode Li ion concentration", if the slope a>0, the set "average negative electrode Li ion concentration" is corrected to be larger. However, in this case, the direction of correction is clear, but the amount of correction is unknown, so the slope a is increased by a certain value and the positive or negative of the slope a is judged again. Then, the correction is repeated until the slope a is closest to 0. Also, if the slope a<0, the "average negative electrode Li ion concentration" is corrected to be smaller in the same manner.

[0028] <Correction by Kalman filter> In this embodiment, the correction may be performed using a Kalman filter. Here, the "Kalman filter" is a calculation method for efficiently estimating an internal, unseen "state" in a mathematical model called a state space model. The purpose of the Kalman filter is to correct the estimation of the true state by weighting two values, an odometry and an observation.

[0029] In the state space model, for example, a certain logical "odometry" and information obtained from an actual sensor or the like are obtained as "observation". From this, the true state is estimated, and correction is performed by weighting based on the odometry and observation. In this embodiment, the full charge capacity F [Ah] of the lithium ion secondary battery 10 can be actually measured as the observation value. Note that the observation value may contain various noises.

[0030] On the other hand, in this embodiment, the full charge capacity F [Ah] of the lithium ion secondary battery estimated by the method for estimating the full charge capacity of a secondary battery is the “estimated value (odometry).” The full charge capacity F [Ah] of the lithium ion secondary battery estimated by the method for estimating the full charge capacity of a secondary battery is corrected by using this “estimated value (odometry)” and “observation.”

[0031] <Optimization of lithium-ion secondary batteries> As described in the Background Art, in a storage battery as described in Patent Document 1, particularly in a secondary battery such as the lithium ion secondary battery 10, it is difficult to estimate the full charge capacity F [Ah] depending on the SOC region. The positive electrode active material of this embodiment is a ternary material called NCM having a lithium transition metal oxide containing all of Ni, Co, and Mn. Here, the case of the ternary lithium ion secondary battery 10, which is the positive electrode active material of this embodiment, will be described.

[0032] Figure 2 shows the estimated full charge capacity F EST >True value F TRUE S is the estimated SOC in EST2 is a graph showing the overall relationship between the estimated SOC [%] and the voltage error ΔE [V]. In the ternary lithium-ion secondary battery 10, for example, as shown in FIG. 2, in a part of the low SOC region (here, less than 25 [%]), a positive correlation is shown, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. In the region of a higher SOC [%] (here, 25 [%] or more and less than 35 [%]), a negative correlation is shown, but the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is somewhat small. In the relatively high SOC region (here, 35 [%] or more and less than 80 [%]), a positive correlation is shown for a long section, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is moderate. In the high SOC region (here, 80 [%] or more), a positive correlation is shown, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is small.

[0033] Figure 3 shows the estimated full charge capacity F EST <True value F TRUE S is the estimated SOC in EST 3 is a graph showing the overall relationship between estimated SOC [%] and voltage error ΔE [V]. As shown in FIG. 3, for example, in a part of the low SOC region (here, less than 20 [%]), a negative correlation is shown, and the change in voltage error ΔE [V] with respect to the change in estimated SOC [%] is large. In a region with a higher SOC [%] (here, 20 [%] or more and less than 35 [%]), a positive correlation is shown, but the change in voltage error ΔE [V] with respect to the change in estimated SOC [%] is small. In a relatively high SOC region (here, 35 [%] or more and less than 80 [%]), a negative correlation is shown for a long section, and the change in voltage error ΔE [V] with respect to the change in estimated SOC [%] is moderate. In a high SOC region (here, 80 [%] or more), a negative correlation is shown, and the change in voltage error ΔE [V] with respect to the change in estimated SOC [%] is small.

[0034] In this embodiment, in order to improve the accuracy of the estimation of the full charge capacity F, it is desirable that there is a strong correlation and that the change in the voltage error ΔE [V] relative to the change in the estimated SOC [%] is sufficiently large. Furthermore, the estimated value F of the full charge capacity F shown in FIG. EST >True value FTRUE S is the estimated SOC in EST The relationship between the full charge capacity F and the voltage error ΔE [V] and the estimated full charge capacity F shown in Figure 3 EST <True value F TRUE S is the estimated SOC in EST In terms of the relationship between the input current [%] and the voltage error ΔE [V], it is desirable to satisfy all of the above conditions simultaneously.

[0035] From this perspective, the region below 25% in Figure 2 and the region below 20% in Figure 3 both have a strong correlation, and the voltage error ΔE [V] changes greatly with respect to the change in estimated SOC [%]. Therefore, it can be seen that the region where the estimated SOC [%] is below 20 [%], which is the common region between these two, is a region suitable for estimating the full charge capacity F.

[0036] Next, the region of 35% or more and less than 80% in Figure 2 and the region of 35% or more and less than 80% in Figure 3 have a strong correlation, and the change in voltage error ΔE [V] relative to the change in estimated SOC [%] is sufficiently large. Therefore, it can be seen that the common region where the estimated SOC [%] is 35% or more and less than 80 [%] is commonly suitable for estimating the full charge capacity F.

[0037] Here, in this embodiment, the target of the method for estimating the full charge capacity F is an in-vehicle driving lithium ion secondary battery 10. As described above, the region where the estimated SOC [%] is less than 20 [%] is suitable for the method for estimating the full charge capacity F because the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. However, the preferred range of SOC [%] for the in-vehicle driving lithium ion secondary battery 10 in this embodiment can be exemplified as 20 to 80 [%]. The method for estimating the full charge capacity F in this embodiment is preferably implemented in the range of SOC [%] that is normally used. Therefore, in this embodiment, the method is implemented in the region where the estimated SOC [%] is 35 [%] or more and less than 80 [%]. Furthermore, taking into consideration the individual differences of the lithium ion secondary battery 10, etc., and taking a margin for safety, the method for estimating the full charge capacity F in this embodiment is implemented in the range of 40 [%] or more and less than 70 [%].

[0038] (Configuration of this embodiment) Hereinafter, a description will be given of the control device 20, which is a full charge capacity estimation device mounted on the vehicle 1 and which performs the method for estimating the full charge capacity of the lithium ion secondary battery 10 according to the present embodiment.

[0039] Hereinafter, the present embodiment, which is an example of the configuration of the present invention, will be described in detail. <Configuration of lithium-ion secondary battery 10> 6 is a perspective view showing the outline of the external configuration of the lithium ion secondary battery 10 of this embodiment. First, the configuration of the lithium ion secondary battery 10 of this embodiment, which is one example of the present invention, will be described.

[0040] As shown in FIG. 6, the lithium ion secondary battery 10 is configured as a cell battery that configures a battery module 10A (see FIG. 8). The lithium ion secondary battery 10 includes a battery case 11 in the shape of a plate-like rectangular parallelepiped having an opening on the upper side. An electrode body 12 is accommodated inside the battery case 11. A nonaqueous electrolyte 13 is filled into the battery case 11 through a liquid inlet. The battery case 11 is made of a metal such as an aluminum alloy, and forms a battery container sealed by a lid. The lithium ion secondary battery 10 also includes a positive electrode external terminal 14 and a negative electrode external terminal 15 used for charging and discharging power. The positive electrode external terminal 14 is electrically connected to a positive electrode current collector terminal 16 inside the battery case 11 via the lid. The negative electrode external terminal 15 is electrically connected to a negative electrode current collector terminal 17 inside the battery case 11 via the lid. The positive electrode current collector terminal 16 is electrically connected to a positive electrode current collector part 33 (see FIG. 7) of the electrode body 12. Moreover, the negative electrode current collector terminal 17 is electrically connected to the negative electrode current collector portion 23 of the electrode body 12 (see FIG. 7).

[0041] <Electrode body 12> FIG. 7 is a schematic diagram showing the configuration of the wound electrode body 12. The electrode body 12 is formed by stacking a large number of negative electrode plates 2 and positive electrode plates 3 with separators 4 arranged between them. The stacked negative electrode plates 2, positive electrode plates 3, and separators 4 are wound to form a flat shape. The negative electrode plates 2 have a negative electrode composite layer 22 formed on a negative electrode current collector 21 made of copper foil as a base material. A negative electrode current collector 23 is provided on one end side of a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L). The negative electrode current collector 23 is configured such that the negative electrode composite layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0042] In the positive electrode plate 3, a positive electrode composite layer 32 is formed on a positive electrode collector 31 made of aluminum foil as a base material. As shown in Fig. 7, a positive electrode collector 33 is provided on the other end side (opposite to the negative electrode collector 23) in a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L) of the positive electrode collector 31. The positive electrode collector 33 does not have the positive electrode composite layer 32 formed thereon, and the metal of the positive electrode collector 31 is exposed.

[0043] <Layer structure of electrode body 12> As shown in FIG. 7, the basic configuration of an electrode assembly 12 of a lithium ion secondary battery 10 includes a negative electrode plate 2, a positive electrode plate 3, and a separator 4.

[0044] The negative electrode plate 2 includes a negative electrode mixture layer 22 on both sides of a negative electrode current collector 21 serving as a negative electrode base material. One end of the negative electrode current collector 21 serves as a negative electrode current collector 23 where the metal is exposed. The positive electrode plate 3 includes a positive electrode mixture layer 32 on both sides of a positive electrode current collector 31 serving as a positive electrode base material. The other end of the positive electrode current collector 31 forms a positive electrode current collecting portion 33 where the metal is exposed.

[0045] A laminate is formed by stacking the negative electrode plate 2 and the positive electrode plate 3 with a separator 4 interposed therebetween. As shown in Fig. 1, this laminate is wound in the longitudinal direction around the winding axis to form a wound-type electrode assembly 12 that is shaped into a flat shape as shown in Fig. 7.

[0046] <Nonaqueous electrolyte 13> The non-aqueous electrolyte 13 of the lithium ion secondary battery 10 of this embodiment shown in FIG. 6 is impregnated in an electrode body 12. The non-aqueous electrolyte 13 is a composition in which a lithium salt is dissolved in an organic solvent. The lithium salt is LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane, sulfur compounds such as ethyl methyl sulfone and butane sultone, and phosphorus compounds such as triethyl phosphate and trioctyl phosphate. One or more of these can be mixed and used as the nonaqueous electrolyte 13. The composition of the nonaqueous electrolyte 13 is not limited to this.

[0047] <Components of electrode body 12> Next, the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are the components that make up the electrode assembly 12, will be described.

[0048] <Negative electrode plate 2> 7, negative electrode mixture layers 22 are formed on both sides of negative electrode current collector 21, which is a negative electrode base material, to form negative electrode plate 2. Negative electrode mixture layer 22 is formed by applying a negative electrode mixture paste to negative electrode current collector 21. After that, negative electrode plate 2 is completed through a drying process, a pressing process, and a cutting process.

[0049] <Negative electrode current collector 21> In this embodiment, the negative electrode current collector 21 is made of Cu foil. The negative electrode current collector 21 serves as a base for the aggregate of the negative electrode mixture layer 22, and also functions as a current collecting member that collects electricity from the negative electrode mixture layer 22. One end of the negative electrode current collector 21 serves as a negative electrode current collecting part 23 where the negative electrode mixture layer 22 is not formed and the metal surface is exposed. In other words, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 via the negative electrode current collector 21, the negative electrode current collecting part 23, and the negative electrode current collecting terminal 17.

[0050] <Negative electrode composite layer 22> In this embodiment, the negative electrode active material is a powdered carbon material made of graphite or the like having a layered structure, and lithium ions Li + It is a material that can absorb and release energy.

[0051] <Positive electrode plate 3> 7, the positive electrode plate 3 is composed of a positive electrode current collector 31, which is a positive electrode base material, and a positive electrode mixture layer 32 applied thereto. The positive electrode mixture layer 32 is formed by applying a positive electrode mixture paste to the positive electrode current collector 31. After that, the positive electrode plate 3 is completed through a drying process, a pressing process, and a cutting process.

[0052] <Positive electrode current collector 31> A positive electrode mixture layer 32 is formed on both sides of a positive electrode current collector 31, which is a positive electrode base material, to form a positive electrode plate 3. In this embodiment, the positive electrode current collector 31 is made of an Al foil. The positive electrode current collector 31 serves as a base for the aggregate of the positive electrode mixture layer 32, and also functions as a current collecting member that collects electricity from the positive electrode mixture layer 32.

[0053] First, the positive electrode base material constituting the positive electrode current collector 31 is exemplified as an Al foil, but may be made of a conductive material made of a metal having good conductivity. As a material having good conductivity, for example, in addition to Al foil, a material containing an Al alloy may be used. The configuration of the positive electrode current collector 31 is not limited to this.

[0054] <Positive electrode mixture layer 32> Positive electrode mixture layer 32 is formed by applying a positive electrode mixture paste to positive electrode current collector 31 and drying it. Positive electrode mixture layer 32 contains additives such as a conductive assistant, a binder, and a dispersant in addition to positive electrode active material particles.

[0055] <Composition of positive electrode active material> The positive electrode active material particles contain a lithium transition metal oxide having a layered crystal structure. The lithium transition metal oxide contains one or more predetermined transition metal elements in addition to Li. The transition metal element contained in the lithium transition metal oxide is preferably at least one of Ni, Co, and Mn. The positive electrode active material of this embodiment is exemplified by a ternary system called NCM having a lithium transition metal oxide containing all of Ni, Co, and Mn.

[0056] The positive electrode active material of the present embodiment is not limited to a lithium transition metal oxide containing all of Ni, Co, and Mn. In addition, a composition containing, for example, Al may be used. In addition, the positive electrode active material may be LiMnO 4 , LiFePO 4 etc. may be used.

[0057] <Separator 4> The separator 4 is a highly insulating nonwoven fabric made of polypropylene or the like, which is a porous resin for holding the nonaqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. As the separator 4, a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, and a porous polyvinyl chloride membrane, or a lithium ion or ion conductive polymer electrolyte membrane can be used alone or in combination.

[0058] <Overall configuration of a vehicle equipped with a secondary battery> Fig. 8 is a block diagram showing an example of the configuration of a vehicle 1 using a lithium-ion secondary battery 10 in an implementation stage. The vehicle 1 illustrated in Fig. 8 is a hybrid automobile. The vehicle 1 includes a control device 20 that also functions as a full charge capacity estimation device for the lithium-ion secondary battery 10, a power control unit (PCU) 30, motor generators 41, 42, an engine 50, a power split device 60, a drive shaft 70, and drive wheels 80. The control device 20 for the lithium-ion secondary battery 10 of this embodiment includes a battery module 10A, a monitoring unit 40, and an ECU (Electronic Control Unit) 100.

[0059] The engine 50 is an internal combustion engine that outputs power by converting the combustion energy generated when a mixture of air and fuel is combusted into kinetic energy of moving elements such as a piston and a rotor.

[0060] Power split device 60 includes, for example, a planetary gear mechanism (not shown) having three rotation shafts, a sun gear, a carrier, and a ring gear. Power split device 60 splits the power output from engine 50 into power for driving motor generator 41 and power for driving drive wheels 80.

[0061] Each of the motor generators 41, 42 is an AC rotating electric machine, for example a three-phase AC synchronous motor with a permanent magnet (not shown) embedded in the rotor. The motor generator 41 is mainly used as a generator driven by the engine 50 via a power split device 60. The electric power generated by the motor generator 41 is supplied to the motor generator 42 or the lithium ion secondary battery 10 via the PCU 30.

[0062] Motor generator 42 mainly operates as an electric motor to drive drive wheels 80. Motor generator 42 is driven by at least one of electric power from lithium ion secondary battery 10 and electric power generated by motor generator 41, and the driving force of motor generator 42 is transmitted to drive shaft 70. On the other hand, when braking the vehicle or reducing acceleration on a downhill slope, motor generator 42 operates as a generator to perform regenerative power generation. The electric power generated by motor generator 42 is supplied to battery module 10A via PCU 30.

[0063] The battery module 10A is configured to include a lithium ion secondary battery 10, which is a multiple cell battery. The lithium ion secondary battery 10 stores power for driving the motor generators 41, 42, and supplies the power to the motor generators 41, 42 through the PCU 30. The lithium ion secondary battery 10 is charged by receiving the generated power through the PCU 30 when the motor generators 41, 42 generate power.

[0064] The monitoring unit 40 includes a voltage measuring device 40a, a current measuring device 40b, and a temperature measuring device 40c. The voltage measuring device 40a of this embodiment detects, for example, the voltage E of each cell battery of the lithium ion secondary battery 10. However, it may also be configured to detect the voltage E of the entire battery module 10A consisting of multiple cells of the lithium ion secondary battery 10 connected in parallel with each other. In this case, the voltage of each cell battery is estimated from the overall voltage. The current measuring device 40b detects the current I input / output to / from the lithium ion secondary battery 10. The temperature measuring device 40c detects the temperature T of each block. Each measuring device outputs a signal indicating the detection result to the ECU 100.

[0065] The monitoring unit of the voltage measuring device 40a and the temperature measuring device 40c is not limited to each cell battery of the lithium ion secondary battery 10, but may be each block, or each set of adjacent cell batteries of multiple (a number less than the number of cells in a block) lithium ion secondary batteries 10. In this embodiment, the internal configuration of the lithium ion secondary battery 10 does not have any particular effect, and it is not necessary to distinguish between the cell batteries of multiple lithium ion secondary batteries 10 or between multiple blocks. Therefore, hereinafter, the monitoring unit is the lithium ion secondary battery 10, and it is generally described as "detecting the voltage E of the lithium ion secondary battery 10," etc.

[0066] The PCU 30 performs bidirectional power conversion between the lithium ion secondary battery 10 and the motor generators 41, 42 in accordance with a control signal from the ECU 100. The PCU 30 is configured to be able to separately control the states of the motor generators 41, 42, and can, for example, put the motor generator 41 in a regenerative state (power generation state) while putting the motor generator 42 in a powering state. The PCU 30 is provided, for example, corresponding to the motor generators 41, 42. The PCU 30 is configured to include two inverters and a converter (neither of which is shown) that boosts a DC voltage supplied to each inverter to an output voltage of the lithium ion secondary battery 10 or higher.

[0067] <ecu100> In this embodiment, the ECU 100 of the control device 20 is a part that performs control as the full charge capacity estimation device.

[0068] The ECU 100 includes a CPU (Central Processing Unit) 101, a memory 102, and an input / output port (not shown) for inputting and outputting various signals. <Memory 102> The memory 102 includes a read only memory (ROM) and a random access memory (RAM). It also includes a storage medium in which programs, maps, etc. are stored, such as an erasable programmable read only memory (EPROM), a solid state drive (SSD), or a hard disk drive (HDD). The ECU 100 controls the charging and discharging of the lithium ion secondary battery 10 by controlling the engine 50 and the PCU 30 based on signals received from each measuring device and the programs and maps stored in the memory 102.

[0069] Fig. 9 is a block diagram showing some of the programs stored in the memory 102. As shown in Fig. 9, the memory 102 stores a program that causes the CPU 101 to function as a current measurement unit 102a. Similarly, a voltage estimation unit 102b, an SOC estimation unit 102c, a voltage measurement unit 102d, a voltage error ΔE calculation unit 102e, an SOC·voltage error storage unit 102f, a straight line calculation unit 102g, a full charge capacity estimation deviation direction calculation unit 102h, and a parameter correction unit 102i are stored.

[0070] (Action of this embodiment) <Flowchart of the method for estimating full charge capacity of a lithium ion secondary battery according to the present embodiment> FIG. 10 is a flowchart showing an example of the procedure of the method for estimating the full charge capacity of a secondary battery according to this embodiment.

[0071] The method for estimating the full charge capacity of a secondary battery is performed within a predetermined SOC range (40 to 70% in this embodiment), so it is first determined whether the estimated SOC value is within the predetermined range (S1).

[0072] In the current measurement step, the current I [A] flowing through the lithium ion secondary battery can be measured in real time by the current measuring device 40b of the monitoring unit 40 shown in FIG. 8. Here, the estimated SOC, S EST The full charge capacity F and the current I [A] are integrated to make ΣI [Ah] = ∫Idt. Then, as a step for estimating the SOC, EST = 1 / full charge capacity F∫Idt", the current I [A] is integrated into the current ΣI [Ah], and the estimated SOC, S EST [%] is calculated and stored in the memory 102. Here, the estimated SOC, S EST If the estimated SOC is not within the predetermined range (in this embodiment, 40% to 70%), the process ends and returns to step S1. EST If the [%] is within the predetermined range, the following process is carried out and then the process proceeds to data save timing? (S2).

[0073] On the other hand, before the data is saved, the following process is performed in parallel with the SOC estimation step. Fig. 11 is a diagram showing an equivalent circuit of the lithium ion secondary battery 10 of this embodiment. Although the method of estimating the SOC is not limited in the present invention, an estimation method using a battery model can be used as an example of SOC estimation. As shown in Fig. 11, the lithium ion secondary battery 10 has a resistance R 0 And the resistor R connected in series with this 1 and capacitor C 1 Such an equivalent circuit can be shown as a parallel circuit with a resistor R 0 , resistance R 1 , capacitor C 1 Then, the combined resistance of the entire equivalent circuit can be calculated.

[0074] Then, in the voltage estimation step, the estimated voltage E, which is the voltage related to the equivalent circuit, is calculated from the combined resistance of the entire equivalent circuit and the current I [A]. EST [V] is calculated and stored in memory 102. At the same time, as a voltage measurement step, the voltage of the lithium ion secondary battery 10 is measured by the voltage measurement device 40a of the monitoring unit 40 shown in FIG. DATA [V] is stored in memory 102.

[0075] Then, in the step of calculating the voltage error ΔE, "voltage error ΔE [V] = measured voltage E DATA [V] - Estimated voltage E EST [V]”, the voltage error ΔE [V] is calculated and stored in memory 102.

[0076] As a step for storing SOC and voltage error, if it is a predetermined timing (e.g., 0.1 [sec]) (S2: YES), proceed to the step of storing the estimated SOC and voltage error (S3). If it is not the predetermined timing (S2: NO), end the process and return to step S1.

[0077] If it is determined that it is time to save data in the data save timing (S2: YES), the calculated estimated SOC, S EST [%] and the voltage error ΔE [V] are stored in memory 102.

[0078] The estimated SOC and voltage error are stored in step S3. EST If the number of data items for the voltage error ΔE [V] and the average current [%] is less than a predetermined number (for example, 50) (S4: NO), the process ends and the process returns to step S1.

[0079] The estimated SOC and voltage error are stored in step S3. EST When the number of data items for the voltage error ΔE [V] and the power dissipation coefficient [%] reaches or exceeds a predetermined number (S4: YES), the process proceeds to a step of calculating the slope of the approximation line (S5).

[0080] <Calculate the slope of the approximate line (S5)> In the calculation of the slope of the approximation line (S5), the estimated SOC in the estimation section is calculated as the slope of the approximation line. EST A number of sets of the power dissipation [%] and voltage error ΔE [V] are plotted on coordinates such as those shown in Figure 4 or Figure 5. Then, multiple regression analysis or the like is performed on the many plotted points P to calculate an approximation line ΔE = a(Sest) + b (where a is the slope and b is the intercept).

[0081] This approximation line is shown in graph L of Figure 4. 1 A downward sloping graph like this, or graph L in Figure 5 2 The graph will slope upwards to the right like this. Here, as a step in calculating the direction of deviation of the estimated full charge capacity, the slope a is calculated. 1 In a downward sloping graph like this, the slope a is a negative value. Also, in the graph L of Figure 5, 2 In a graph sloping upwards to the right like this, the slope a is positive.

[0082] In the step of "Is the calculated slope positive?" (S6), if the slope a calculated in the step of "Calculate the slope of the approximate line" (S5) is positive (S6: YES), the process proceeds to the process of correcting the parameters in the direction of decreasing the full charge capacity F (S7). If the slope a calculated in the step of "Calculate the slope of the approximate line" (S5) is negative (S6: NO), the process proceeds to the process of correcting the parameters in the direction of increasing the full charge capacity F (S8).

[0083] The parameter correction in the direction of decreasing the full charge capacity F (S7) is executed by a program stored in the parameter correction unit 102i. As a step of correcting the negative electrode average Li ion concentration [%], which is a parameter correction step, the negative electrode average Li ion concentration [%] is corrected by a constant value in a direction to decrease so that the slope a approaches zero. Once the correction is performed, the slope a is calculated again, and the correction is completed when the slope a approaches zero.

[0084] Correcting the parameters in the direction of increasing the full charge capacity F (S8) is also executed by the program stored in the parameter correction unit 102i. As a step of correcting the negative electrode average Li ion concentration [%], which is a parameter correction step, correction is performed by a constant value at a time in the direction of increasing the negative electrode average Li ion concentration [%] so that the slope a approaches zero. This is executed by the program stored in the parameter correction unit 102i. Once the correction is performed, the slope a is calculated again, and the correction is completed when the slope a is closest to zero.

[0085] When the procedure of correcting the parameters in the direction of decreasing the full charge capacity F (S7) or correcting the parameters in the direction of increasing the full charge capacity F (S8) is completed, the procedure of the method for estimating the full charge capacity F of a secondary battery of this embodiment is once completed. In addition, the process is started at a predetermined timing, for example, a certain time or a certain travel distance.

[0086] (Action of this embodiment) In the method for estimating full charge capacity using the secondary battery full charge capacity estimation device of this embodiment, the estimated voltage E EST [V] and the estimated SOC, S EST [%]. Furthermore, the measured voltage E DATA [V] is measured directly and the estimated voltage E EST Then, the voltage error ΔE [V] is calculated by subtracting the estimated SOC, S EST From the relationship between the full charge capacity F and the voltage error ΔE [V], the estimated full charge capacity F EST It is judged whether [Ah] is too high or too low. If it is too low, the estimated full charge capacity F is calculated. EST Correct the value by increasing [Ah]. If the value is too large, correct the estimated full charge capacity F. EST [Ah] is corrected to decrease. In this way, the estimated full charge capacity F EST By accurately correcting [Ah], the estimated SOC, S EST [%] can be accurately estimated, and control suited to the characteristics of the target lithium-ion secondary battery 10 can be performed. As a result, the performance of the target lithium-ion secondary battery 10 can be maximized, and the deterioration of the battery can be effectively suppressed.

[0087] (Experimental Example) The estimation method using the full charge capacity estimation device of this embodiment has the configuration and function as described above. The operation of the estimation method using such a full charge capacity estimation device was confirmed by the following experiment.

[0088] Figure 12(a) shows the measured voltage E DATA Estimated voltage E for [V] EST The horizontal axis shows the passage of time [s], and the vertical axis shows the voltage [V]. DATA [V] is shown by a dashed line, and the estimated voltage E EST In Fig. 12(a), the measured voltage E DATA The dashed line showing [V] and the estimated voltage E EST The solid lines indicating [V] almost overlap, making it difficult to distinguish.

[0089] FIG. 12(b) is a graph showing the voltage error ΔE [V] over time. That is, the measured voltage E DATA [V] to estimate voltage E EST In Figure 12(a), the difference is difficult to distinguish, but in Figure 12(b), the voltage error ΔE is initially about 0.025 [V], but after about 5000 [s], the graph shows that it converges to roughly 0.00 [V].

[0090] Figure 12(c) shows the true SOC value S TRUE S is the estimated SOC for [%] EST The vertical axis shows the SOC [%]. The dashed line shows the true SOC value S TRUE [%] is the value of SOC [%] that can be regarded as a true value obtained by integrating the input current derived from strict observation. In contrast, the estimated SOC S EST [%] is a value estimated by a voltage-based method using a battery model. There is a discrepancy until roughly 5000 [s] has passed, but after that the graphs overlap and it becomes difficult to distinguish.

[0091] FIG. 12(d) is a graph showing the SOC error ΔS [%] over time. The vertical axis is the SOC, i.e., the true SOC value S TRUE [%] is the estimated SOC, S EST The graph shows the SOC error ΔS [%] with the error [%] subtracted. In Figure 12(d), the error initially ranged from about -8[%] to +3[%], but after about 5000[s], the graph shows that it converges to roughly 0[%].

[0092] FIG. 12(e) shows the true value F of the full charge capacity F over time. TRUE Estimated full charge capacity F for [Ah] EST The vertical axis shows the full charge capacity F [Ah]. The true value F of the full charge capacity F is shown by the dashed line. TRUE [Ah] is the value of the full charge capacity F [Ah] that can be considered as the true value derived from strict observation. The solid line shows the estimated value F of the full charge capacity F. EST Here, the initial estimated value F is shown by the solid line, as is the voltage error ΔE [V] shown in FIG. 12(b) and the SOC error ΔS [%] shown in FIG. 12(d). EST [Ah] is the true value F of the full charge capacity F shown by the dashed line TRUE There is a deviation of about 5000[s] from [Ah]. After about 5000[s], the deviation converges to roughly 0[Ah].

[0093] From the above experimental results, it has been demonstrated that the method for estimating full charge capacity according to the present embodiment can estimate the full charge capacity F extremely stably and accurately. (Effects of this embodiment) (1) According to the method and device for estimating a full charge capacity of the lithium ion secondary battery 10 of the present embodiment, there is an advantage that the full charge capacity F of the lithium ion secondary battery 10 can be easily estimated.

[0094] (2) Therefore, the performance of the target lithium ion secondary battery 10 can be maximized and the deterioration of the battery can be effectively suppressed. (3) Voltage error ΔE [V] and estimated SOC S EST [%] shows the relationship with the straight line ΔE=a(S EST ) + b (where a is the slope and b is the intercept). Then, the estimated value F of the full charge capacity F [Ah] is calculated based on the slope a of the calculated line. EST and the true value of the full charge capacity [Ah] F TRUE The direction of deviation ΔF of the estimated full charge capacity is calculated, which indicates the magnitude relationship between the voltage error ΔE [V] and the estimated SOC S EST By using [%], you can accurately estimate the F EST This has the effect of making it possible to estimate the full charge capacity F [Ah].

[0095] (4) Voltage error ΔE [V] and estimated SOC S EST Each of the percentages can be calculated simply by measuring the voltage E and current I of the lithium-ion secondary battery 10. This has the effect of making it possible to easily calculate the percentages using the control device 20 of the conventional lithium-ion secondary battery 10 without the need for any new device.

[0096] (5) Furthermore, the full charge capacity estimate F EST Instead of [Ah], a parameter used for controlling the lithium ion secondary battery 10, for example, the negative electrode average Li ion concentration [%], is corrected. This has the effect of easily optimizing the control of the lithium ion secondary battery 10.

[0097] (6) Moreover, the method for estimating the full charge capacity of the lithium ion secondary battery 10 of the present embodiment is performed in advance at an SOC (for example, 40 to 70% in the present embodiment). This has the effect of enabling the full charge capacity F of the lithium ion secondary battery 10 to be estimated more accurately.

[0098] (7) By changing the data storage timing (S2) or the specified value for the number of pieces of data (S4), it is possible to perform control that is more suitable for the target lithium ion secondary battery 10.

[0099] (Another example) In this embodiment, the secondary battery is described as being a cell battery of a lithium-ion secondary battery 10 used for driving hybrid cars and the like, but the present invention is not limited to this. For example, the secondary battery is not limited to a lithium-ion secondary battery, and may be other non-aqueous electrolyte secondary batteries, or alkaline secondary batteries such as solid-state secondary batteries and nickel-metal hydride batteries.

[0100] Furthermore, the purpose is not limited to driving a vehicle, but may be for use as a stationary or portable device battery. In this embodiment, the lithium ion secondary battery 10 is exemplified as a cell battery constituting the battery module 10A, which is an assembled battery, but it may be controlled by a single cell battery or may be a battery pack having multiple battery modules. In this case, the current I [A] and voltage E [V] may be measured by directly measuring the cell battery or by measuring the assembled battery.

[0101] In this embodiment, the estimation of the full charge capacity F is performed with the SOC in the range of 40 to 70%. However, it can also be performed with the SOC in the range of 20% or less. Furthermore, the range can be optimized by a person skilled in the art to, for example, 30 to 80% according to the characteristics of the battery when a different positive electrode active material is used. Depending on the characteristics of the battery, the estimation of the full charge capacity F may be performed without limiting the SOC.

[0102] The data storage timing (S2) and the specified number of pieces of data (S4) can be optimized as appropriate by those skilled in the art depending on the characteristics of the battery, the capabilities of the control device 20, the amount of noise and variation, and the like.

[0103] ○Estimated voltage E EST [V] and the estimated SOC, S EST In this embodiment, [%] is estimated by measuring the same type of lithium ion secondary battery by complex impedance measurement or the like, and by Ohm's law or the like using an equivalent circuit as shown in Fig. 11, but is not limited to this. For example, it may be estimated by a detailed Newman model using a diffusion equation.

[0104] In this embodiment, the voltage error ΔE [V] is calculated by: DATA -Estimated voltage E EST The voltage error ΔE [V] = estimated voltage E EST -Measured voltage E DATA In this case, the positive and negative signs of the slope a are reversed.

[0105] ○ Estimated full charge capacity F EST may be further corrected using a Kalman filter or the like. In this embodiment, the estimated full charge capacity F EST Instead of the correction of the negative electrode average Li ion concentration, the negative electrode average Li ion concentration is corrected as a control parameter. The parameter is not limited to this, and other parameters that can be used to control the secondary battery may be corrected.

[0106] The numerical values ​​and numerical ranges in the present embodiment are given as examples and are not limited thereto. Those skilled in the art can appropriately optimize the values ​​and ranges according to the characteristics of the battery. The flowchart shown in Fig. 10 is an example of an embodiment for the purpose of explanation, and is not intended to be limiting. Those skilled in the art may add, delete, replace, or modify steps in the embodiment.

[0107] It goes without saying that those skilled in the art may add, delete or modify the configuration of the present invention without departing from the scope of the claims. [Explanation of symbols]

[0108] I[A]…Current ΣI [Ah]…Current which is the accumulated current I [A] E EST [V]…Estimated voltage E DATA [V]…Measurement voltage ΔE[V]…Voltage error a…Slope of the line in “ΔE=a(Sest)+b” F [Ah]…Full charge capacity F EST [Ah]…Estimated full charge capacity F F TRUE [Ah]…True value of full charge capacity F ΔF…Direction of deviation in estimated full charge capacity P...plot point R[mΩ]…Internal resistance S EST [%]…Estimated SOC S TRUE [%]…SOC true value ΔS[%]…SOC error L 1 ~L 5 …graph T[°C]…Temperature 1. Vehicle 10...Lithium-ion secondary battery (secondary battery) 10A…Battery module 11…Battery case 12...Electrode body 13...Nonaqueous electrolyte 14…Positive external terminal 15...Negative external terminal 16…Positive current collecting terminal 17...Negative current collecting terminal 2...Negative electrode plate 21...Negative electrode current collector 22...Negative electrode composite material layer 23...Negative electrode current collector 3…Positive electrode plate 31...Positive electrode current collector 32...Positive electrode mixture layer 33…Positive electrode current collector 4…Separator 20...Control device (full charge capacity estimation device) 30…PCU 40…Surveillance unit 40a...Voltage measuring device 40b…Current measuring device 40c…Temperature measuring device 100…ECU (computer) 101...CPU 102…Memory 102a...Current measuring section 102b...Voltage estimation unit 102c…SOC estimation department 102d…Voltage measurement section 102e…Voltage error ΔE calculation unit 102f…SOC / Voltage error memory section 102g…Straight line calculation section 102h…Full charge capacity estimation deviation direction calculation section 102i…Parameter correction section

Claims

1. S, which is the estimated SOC of the target secondary battery ＥＳＴ a step of estimating SOC [%]; Estimated voltage E ＥＳＴ a voltage estimation step of estimating [V]; The measured voltage E of the secondary battery ＤＡＴＡ a voltage measurement step of measuring [V]; The estimated voltage E ＥＳＴ The measured voltage E measured at the same time as [V] ＤＡＴＡ A voltage error ΔE calculation step of calculating a voltage error ΔE [V] which is a voltage difference between the input voltage Vcc and the reference voltage Vcc [V]; The voltage error ΔE [V] and the S ＥＳＴ a step of storing a plurality of sets of values ​​of the estimated SOC and voltage error [%] at different times; The voltage error ΔE [V] derived from a set of a plurality of values ​​stored at different times in the step of storing the estimated SOC and voltage error and the estimated SOC at the same time, S ＥＳＴ The straight line ΔE = a(S ＥＳＴ a step of calculating a straight line to derive a+b (where a is the slope and b is the intercept); Based on the slope a of the straight line derived in the straight line calculation step, the estimated value F of the full charge capacity F [Ah] is calculated. ＥＳＴ and the true value of the full charge capacity F [Ah] ＴＲＵＥ a step of calculating a deviation direction of the full charge capacity estimation ΔF, which indicates a magnitude relationship between the full charge capacity estimation deviation direction ΔF and the full charge capacity estimation deviation direction ΔF; A method for estimating a full charge capacity of a secondary battery, comprising:

2. The SOC estimation step includes a current measurement step of measuring a current I [A] flowing through the secondary battery. The estimated voltage E is calculated based on the current I [A] and the internal resistance R [mΩ] of the secondary battery model. ＥＳＴ a voltage estimation step of estimating [V]; The estimated SOC of the secondary battery is estimated from the current ΣI [Ah], which is the integrated current I [A]. ＥＳＴ 2. The method for estimating a full charge capacity of a secondary battery according to claim 1, further comprising the step of estimating a full charge capacity of the secondary battery based on the estimated full charge capacity.

3. Based on the full charge capacity estimation deviation direction ΔF calculated in the step of calculating the full charge capacity estimation deviation direction, the straight line ΔE=a(S ＥＳＴ ) + b so that the slope a of the full charge capacity F [Ah] is horizontal. ＥＳＴ Step of correcting the estimated full charge capacity [Ah] 2. The method for estimating a full charge capacity of a secondary battery according to claim 1, further comprising:

4. Based on the full charge capacity estimation deviation direction ΔF calculated in the step of calculating the full charge capacity estimation deviation direction, the straight line ΔE=a(S ＥＳＴ a step of correcting parameters used to control the secondary battery so that the slope a of the slope a of the slope a+b becomes horizontal.

2. The method for estimating a full charge capacity of a secondary battery according to claim 1, further comprising:

5. The parameter correction step includes a step of correcting an estimated value of the negative electrode average Li ion concentration [%] as the parameter.

5. The method for estimating a full charge capacity of a secondary battery according to claim 4, further comprising:

6. The method for estimating the full charge capacity of a secondary battery according to claim 5, characterized in that the step of correcting the negative electrode average Li ion concentration [%] comprises a procedure of correcting the estimated value of the negative electrode average Li ion concentration [%] by a constant value in a direction in which a deviation in the estimation of the full charge capacity estimation deviation direction ΔF becomes smaller until a slope a is reversed from positive to negative.

7. In the step of estimating the SOC, the estimated SOC of the secondary battery, S ＥＳＴ The method for estimating the full charge capacity of a secondary battery as described in claim 1, further comprising a step of SOC determination in which the method for estimating the full charge capacity of a secondary battery is executed only when the value of [%] is within a preset SOC range.

8. 2. The method for estimating a full charge capacity of a secondary battery according to claim 1, wherein the secondary battery is a lithium ion secondary battery.

9. 8. The method for estimating a full charge capacity of a secondary battery according to claim 7, wherein the secondary battery is a ternary lithium ion secondary battery, and the preset SOC range is set within a range of 40% or more and 70% or less.

10. Voltage E of the target secondary battery ＤＡＴＡ A voltage measuring device that measures the voltage E [V], a current measuring device that measures the current I [A] of the secondary battery, and ＤＡＴＡ a secondary battery full charge capacity estimation device including: a current I [A] inputted to the secondary battery; and a computer for estimating a full charge capacity F [Ah] of the secondary battery, The computer includes: SOC of the secondary battery, S ＥＳＴ An SOC estimation unit that estimates [%]; Voltage E ＥＳＴ A voltage estimation unit that estimates [V]; The voltage E of the secondary battery ＤＡＴＡ A voltage measurement unit that measures [V]; The voltage E ＥＳＴ [V] and the voltage E ＤＡＴＡ [V], and the voltage error ΔE [V], which is the difference between ＥＳＴ a SOC / voltage error storage unit that stores a plurality of pairs of values ​​[%] at different times; The voltage error ΔE [V] derived from a set of a plurality of values ​​stored at different times in the SOC / voltage error storage unit and the S ＥＳＴ The straight line ΔE = a(S ＥＳＴ a) + b (where a is the slope and b is the intercept); The estimated value F of the full charge capacity F [Ah] is calculated based on the slope a of the straight line calculated by the straight line calculation unit. ＥＳＴ [Ah] and the true value of the full charge capacity F [Ah] ＴＲＵＥ a full charge capacity estimation deviation direction calculation unit that calculates a full charge capacity estimation deviation direction ΔF that indicates a magnitude relationship with [Ah]; A secondary battery full charge capacity estimation device comprising:

11. The SOC estimation unit is A current measuring unit that measures a current I [A] flowing through the secondary battery; The voltage E from the current I [A] and the internal resistance R [mΩ] of the secondary battery model ＥＳＴ A voltage estimation unit that estimates [V], The SOC of the secondary battery is estimated from the current ΣI [Ah], which is the integrated current I [A]. ＥＳＴ 11. The device for estimating a full charge capacity of a secondary battery according to claim 10, wherein the full charge capacity is estimated as [%].

12. Based on the full charge capacity estimation deviation direction ΔF calculated by the full charge capacity estimation deviation direction calculation unit, the straight line ΔE=a(S ＥＳＴ ) + b so that the slope a of the corrected full charge capacity F [Ah] is horizontal. ＥＳＴ A full charge capacity estimate correction unit that corrects [Ah] 12. The device for estimating a full charge capacity of a secondary battery according to claim 11, further comprising:

13. Based on the full charge capacity estimation deviation direction ΔF calculated by the full charge capacity estimation deviation direction calculation unit, the straight line ΔE=a(S ＥＳＴ a parameter correction unit that corrects parameters used to control the secondary battery so that a gradient a of the gradient a of the gradient a of the gradient b becomes horizontal.

12. The device for estimating a full charge capacity of a secondary battery according to claim 11, further comprising:

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