Method for estimating full charge capacity of secondary battery and device for estimating full charge capacity of secondary battery

Abstract

The present invention addresses the problem of easily estimating the full charge capacity of a secondary battery. A current [Ah] of a target lithium ion secondary battery is measured to estimate SOC [%], a voltage [V] is estimated from a battery model, and a voltage error [V] is stored (S3). If the amount of data stored is equal to or greater than a predetermined value (S4: YES), an approximate straight line is calculated from the estimated SOC and the voltage error (S5). On the basis of the slope, it is determined whether the estimated full charge capacity of the secondary battery is greater than or less than a true value (S6), and on the basis of the slope, the estimation of a parameter closely related to the full charge capacity [Ah] is corrected (S7, S8).

Description

Technical Field

[0001] The present invention relates to a method for estimating the full charge capacity of a secondary battery and an apparatus for estimating the full charge capacity of a secondary battery. More specifically, the present invention relates to a method for estimating the full charge capacity of a secondary battery and an apparatus for estimating the full charge capacity of a secondary battery, which can easily estimate the full charge capacity of the secondary battery. Background Art

[0002] Secondary batteries, such as ternary lithium ion secondary batteries, have a high voltage and a large full charge capacity, and thus can be suitably used for driving applications such as electric vehicles. In such a lithium ion secondary battery, deterioration occurs due to use, and the full charge capacity (FCC: Full Charge Capacity) [Ah] may decrease. If the full charge capacity decreases, an offset occurs in the estimation of the state of charge (SOC) [%]. Therefore, by accurately estimating the full charge capacity [Ah], the battery performance of the secondary battery can be fully exhibited, and the secondary battery can be controlled in a manner that suppresses deterioration.

[0003] Therefore, in the invention described in Patent Document 1, the full charge capacity [Ah] is estimated from a curve representing the relationship between the SOC [%] and the open circuit voltage (OCV) [V] and the current accumulation amount [Ah] of the battery. Prior Art Documents Patent Documents

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-178156 Summary of the Invention Problems to be Solved by the Invention

[0005] However, in the storage battery described in Patent Document 1, since the full charge capacity [Ah] is estimated by using the current integration method, the noise of the current sensor is accumulated. As a result, there is a possibility that the full charge capacity [Ah] cannot be accurately estimated, and thus it is difficult to accurately estimate the full charge capacity [Ah].

[0006] Therefore, the subject of the present disclosure is to easily estimate the full charge capacity of a secondary battery. Means for Solving the Problems

[0007] In order to solve the above problems, the method for estimating the full charge capacity of a secondary battery according to the present invention is characterized in that it includes the following steps: a step of estimating the SOC, in which the estimated SOC S EST [%] of the target secondary battery is estimated; a step of estimating the voltage, in which the estimated voltage E EST[V]Perform estimation; a voltage measurement step to measure the measured voltage E of the secondary battery DATA [V]Perform measurement; a voltage error ΔE calculation step to calculate the estimated voltage E EST [V]Estimated and the measured voltage E measured at the same time DATA [V]The voltage difference, i.e., the voltage error ΔE [V]; a step of storing the estimated SOC · voltage error, changing the time to store the voltage error ΔE [V] and the S at the same time EST [%] of multiple value groups; a straight line calculation step to derive a straight line ΔE = a(S EST [%] representing the relationship between the voltage error ΔE [V] and the estimated SOC, i.e., S, at the same time EST ) + b (where a is the slope and b is the intercept), and the voltage error ΔE is derived from the multiple value groups stored by changing the time in the step of storing the estimated SOC · voltage error; and a step of calculating the estimated offset direction of the full charge capacity, based on the slope a of the straight line derived in the straight line calculation step, calculating the estimated value F of the full charge capacity F [Ah] representing EST The magnitude relationship between the true value F of the full charge capacity F [Ah] TRUE And the estimated offset direction ΔF of the full charge capacity.

[0008] The step of estimating the SOC may include: a current measurement step to measure the current I [A] flowing through the secondary battery; and a voltage estimation step to estimate the estimated voltage E EST [V]According to the current I [A] and the internal resistance R [mΩ] based on the battery model of the secondary battery, the estimated voltage E EST [V]Perform estimation, and can estimate the estimated SOC, i.e., S, of the secondary battery estimated according to the accumulated current I [A], i.e., the current ΣI [Ah]

[0009] In addition, a step of correcting the estimated value of the full charge capacity may be included. Based on the estimated offset direction ΔF of the full charge capacity calculated in the step of calculating the estimated offset direction of the full charge capacity, according to the straight line ΔE = a(S EST ) + b, the slope a becomes horizontal to correct the estimated value F EST [Ah] of the full charge capacity F [Ah].

[0010] Alternatively, a parameter correction step may be included. Based on the estimated offset direction ΔF of the full charge capacity calculated in the step of calculating the estimated offset direction of the full charge capacity, according to the straight line ΔE = a(S EST) The parameter used in the control of the above secondary battery is corrected in such a way that the slope a of +b becomes horizontal. In this case, the step of the above parameter correction may also include the step of correcting the average Li ion concentration [%] of the negative electrode, and correcting the estimated value of the average Li ion concentration [%] of the negative electrode as the above parameter. In addition, the following process may also be included in the step of correcting the average Li ion concentration [%] of the negative electrode: in the direction in which the estimated shift in the full charge capacity estimation shift direction ΔF decreases, the estimated value of the average Li ion concentration [%] of the negative electrode is corrected by a fixed value each time until the slope a reverses in sign.

[0011] The step of SOC estimation may include the step of SOC determination, and the full charge capacity estimation method of the secondary battery is executed only when the SOC of the above secondary battery, i.e., S EST [%], is within the range of the pre-set SOC. This can be appropriately implemented when the above secondary battery is a lithium ion secondary battery. In this case, the above secondary battery may be a ternary lithium ion secondary battery, and the range of the pre-set SOC may be set within the range of 40 [%] or more and 70 [%] or less.

[0012] In addition, the full charge capacity estimation device of the secondary battery of the present invention is characterized in that it includes: an SOC estimation unit that estimates the SOC, i.e., S EST [%], of the secondary battery as an object; a voltage estimation unit that estimates the voltage E EST [V]; a voltage measurement unit that measures the voltage E DATA [V] of the above secondary battery; an SOC·voltage error storage unit that stores, at different times, the voltage error ΔE [V] (which is the difference between the above voltage E EST [V] and the above voltage E DATA [V]) and multiple value groups of the above S EST [%] at the same time; a straight line calculation unit that derives a straight line ΔE = a(S EST ), which represents the relationship between the voltage error ΔE [V] (derived from multiple value groups stored at different times in the above SOC·voltage error storage unit) and the above S EST [%] at the same time, +b (where a is the slope and b is the intercept); and a full charge capacity estimation shift direction calculation unit that calculates, based on the slope a of the straight line derived in the above straight line calculation unit, the full charge capacity estimation shift direction ΔF that represents the magnitude relationship between the estimated value F EST [Ah] of the full charge capacity F [Ah] and the true value F TRUE [Ah] of the full charge capacity F [Ah].

[0013] The above SOC estimation unit may include: a current measurement unit that measures the current I [A] flowing through the secondary battery; and a voltage estimation unit that estimates the voltage E EST [V] based on the current I [A] and the internal resistance R [mΩ] of the battery model based on the secondary battery, and can estimate the SOC of the secondary battery, i.e., S EST [%], estimated from the accumulated current I [A], i.e., the current ΣI [Ah].

[0014] In this case, a full charge capacity estimated value correction unit may be provided, and based on the full charge capacity estimation offset direction ΔF calculated in the above full charge capacity estimation offset direction calculation unit, the estimated value F of the full charge capacity F [Ah] is corrected in such a way that the slope a of the above straight line ΔE = a(S EST ) + b becomes horizontal. EST [Ah]

[0015] Alternatively, a parameter correction unit may be provided, and based on the full charge capacity estimation offset direction ΔF calculated in the above full charge capacity estimation offset direction calculation unit, the parameters used in the control of the secondary battery are corrected in such a way that the slope a of the above straight line ΔE = a(S EST ) + b becomes horizontal. Advantages of the Invention

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

[0017] Figure 1 is a graph showing the change in voltage [V] with respect to the change in capacity [Ah] in the case of the estimated value F EST <true value F TRUE , the case where the estimated value F EST = true value F TRUE , and the case where the estimated value F EST <true value F TRUE . Figure 2 is a graph showing the overall relationship between the estimated SOC [%] and the voltage error ΔE [V] in the case where the estimated value F of the full charge capacity EST > true value F TRUE . Figure 3 is a graph showing the overall relationship between the estimated SOC [%] and the voltage error ΔE [V] in the case where the estimated value F of the full charge capacity EST <true value F TRUE . Figure 4 is a graph showing the estimated value F of the full charge capacityEST <True value F TRUE Graph of the estimation interval of the relationship between the estimated SOC [%] and the voltage error ΔE [V] in the case of. Figure 5 Shows the estimated value F of the full charge capacity EST > True value F TRUE Graph of the estimation interval of the relationship between the estimated SOC [%] and the voltage error ΔE [V] in the case of. Figure 6 Is a perspective view showing an outline of the external configuration of the lithium ion secondary battery of the present embodiment. Figure 7 Is a schematic diagram showing the configuration of the wound electrode body. Figure 8 Is a block diagram showing an example of the configuration of a vehicle using a lithium ion secondary battery at the implementation stage. Figure 9 Is a block diagram showing the detailed content of the configuration of the memory of the ECU of the full charge capacity estimation device of the present embodiment. Figure 10 Is a flowchart showing an example of the process of the full charge capacity estimation method of the secondary battery of the present embodiment. Figure 11 Is a diagram showing the equivalent circuit of the lithium ion secondary battery of the present embodiment. Figure 12 (a) shows the estimated voltage E with respect to the measured voltage E over time DATA [V] of the estimated voltage E EST [V] graph. Figure 12 (b) is a graph showing the voltage error ΔE [V] over time. Figure 12 (c) shows the estimated SOC, which is S, with respect to the SOC true value S over time TRUE [%] of the estimated SOC, which is S EST [%] graph. Figure 12 (d) is a graph showing the SOC error ΔS [%] over time. Figure 12 (e) shows the estimated value F of the full charge capacity with respect to the true value F of the full charge capacity over time TRUE [Ah] of the full charge capacity of the estimated value F EST [Ah] graph. Detailed implementation mode

[0018] The following is referred to Figures 1 - 12 Taking the full charge capacity estimation device of the lithium ion secondary battery 10 mounted on a vehicle as an example, the full charge capacity estimation method of the secondary battery of the present invention and the full charge capacity estimation device of the secondary battery will be described.

[0019] <Principle of the present embodiment> Figure 1 is divided into the estimated value F EST than the true value F TRUE In the case of being small, the estimated value F EST and the true value F TRUE In the case of being equal and the estimated value F EST than the true value F TRUE In the case of being large, a graph showing the change in voltage [V] with respect to the change in capacity [Ah] is shown.

[0020] In the case of the lithium-ion secondary battery 10, the relationship between the actual capacity [Ah] and the voltage [V] is the graph L 4 The true value F of the full charge capacity F represented by TRUE [Ah]. In addition, for the estimated value F of the estimated full charge capacity F EST [Ah] is lower than the true value F of the full charge capacity F TRUE [Ah], the slope as shown in the graph L 3 increases. Conversely, for the estimated value F of the estimated full charge capacity F EST [Ah] is higher than the true value F of the full charge capacity F TRUE [Ah], the slope as shown in the graph L 5 decreases. Thus, the magnitude of the voltage [V] variation associated with the estimation error of the full charge capacity F is in the order of graph L 3 > graph L 4 > graph L 5 .

[0021] When estimating the estimated value F of the full charge capacity F based on this characteristic EST [Ah] is smaller than the true value F of the full charge capacity F TRUE [Ah], as the capacity, i.e., the SOC, increases, it shifts more towards the side where the voltage error ΔE [V] increases. Conversely, when the estimated value F of the estimated full charge capacity F EST [Ah] is larger than the true value F of the full charge capacity F TRUE [Ah], as the capacity, i.e., the SOC, increases, it shifts more towards the side where the voltage error ΔE [V] decreases.

[0022] Figure 4 is a graph showing the estimated range of the relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value F of the full charge capacity F EST < the true value F TRUE . In addition, Figure 5 is a graph showing the estimated range of the relationship between the estimated SOC [%] and the voltage error ΔE [V] when the estimated value F of the full charge capacity F EST > the true value F TRUE .

[0023] <Estimation of full charge capacity F> As Figure 4 shown, if the estimated SOC S in the estimation interval EST [%] increases, the voltage error ΔE decreases. It can be known that the estimated value F of the full charge capacity F EST <true value F TRUE . On the other hand, as Figure 5 shown, if the estimated SOC in the estimation interval, i.e., S EST [%] increases, the voltage error ΔE increases. It can be known that the estimated value F of the full charge capacity F EST > true value F TRUE .

[0024] Therefore, the graph L of the straight line derived from the Figure 4 data points, 1 or the graph L of the straight line derived from the Figure 5 data points 2 can both be expressed as voltage error ΔE = a(Sest) + b (where a is the slope and b is the intercept). In this graph L 1 or L 2 , it can be known that when the slope a < 0 and it becomes a straight line descending to the right, the estimated value F of the full charge capacity F EST > true value F TRUE . In addition, it can be known that when the slope a > 0 and it becomes a straight line ascending to the right, the estimated value F of the full charge capacity F EST < true value F TRUE .

[0025] <Correction of the estimated value F of the full charge capacity based on the slope a EST > It should be noted that in this determination based on the slope a, it is possible to estimate whether the estimated value F EST is too large or too small relative to the true value F TRUE , but the specific error of the estimated value F EST relative to the true value F TRUE cannot be calculated. Of course, the true value F of the full charge capacity F TRUE [Ah] cannot be directly calculated either. Therefore, the slope a is used as the "full charge capacity estimation deviation direction ΔF" and used as the direction of the correction value of the estimated value F EST of the full charge capacity.

[0026] That is, when the slope a > 0, the estimated value F of the full charge capacity F ESTThe correction increases. However, although the correction direction is clear, the correction amount is unknown. Therefore, a fixed value is added each time, and the sign of the slope a is judged again. And the correction is repeated until it is closest to the slope a = 0. In addition, when the slope a < 0, the estimated value F of the full charge capacity F is corrected to decrease by the same method. EST The correction decreases.

[0027] <Parameter correction> It should be noted that the purpose of estimating the full charge capacity in this embodiment is not to obtain the exact absolute value of the full charge capacity F [Ah] itself, but to appropriately control the lithium-ion secondary battery 10 as the object. Therefore, for example, by accurately estimating the "average Li-ion concentration in the negative electrode", which is a parameter affecting the full charge capacity F [Ah], the lithium-ion secondary battery 10 as the object can be appropriately controlled. Here, it is known that there is a relationship of full charge capacity F [Ah] ∝ "average Li-ion concentration in the negative electrode". Therefore, regarding the "average Li-ion concentration in the negative electrode", when the slope a > 0, the correction is made in such a way that the set "average Li-ion concentration in the negative electrode" increases. However, even in this case, although the correction direction is clear, the correction amount is unknown. Therefore, a fixed value is added each time, and the sign of the slope a is judged again. And the correction is repeated until it is closest to the slope a = 0. In addition, when the slope a < 0, the "average Li-ion concentration in the negative electrode" is corrected to decrease by the same method.

[0028] <Correction based on Kalman filter> In this embodiment, the correction can be performed by Kalman filter. Here, the "Kalman filter" is a calculation method for effectively estimating the internal invisible "state" in a mathematical model called the state space model. The purpose of the Kalman filter is to correct the estimation of the true state by weighting and using the two values of the estimated value (odometry) and the observed value (observation).

[0029] In the state space model, for example, a certain logic "estimated value (odometry)" and the information actually obtained from sensors, etc. are taken as the "observed value (observation)". From this, the true state is estimated, and weighted correction is performed based on these estimated value (odometry) and observed value (observation). In this embodiment, as the observed value, the full charge capacity F [Ah] of the lithium-ion secondary battery 10 can be actually measured. It should be noted that the observed value may contain various noises.

[0030] On the other hand, in the present embodiment, the full charge capacity F [Ah] of the lithium-ion secondary battery estimated by the full charge capacity estimation method of the secondary battery is the "estimated value (odometry)". The full charge capacity F [Ah] of the lithium-ion secondary battery estimated by the full charge capacity estimation method of the secondary battery is corrected by using this "estimated value (odometry)" and the "observed value (observation)".

[0031] <Optimization in Lithium-Ion Secondary Batteries> As described in the background art, in secondary batteries such as the storage battery described in Patent Document 1, particularly the lithium-ion secondary battery 10, it is difficult to estimate the full charge capacity F [Ah] according to the SOC region. The positive electrode active material of the present embodiment exemplifies a ternary system material called so-called NCM having a lithium transition metal oxide containing all elements of Ni, Co, and Mn. Here, the case where the ternary lithium-ion secondary battery 10 of the positive electrode active material of the present embodiment is taken as an object will be described.

[0032] Figure 2 is a graph showing the estimated SOC, i.e., S EST > true value F TRUE in the case of the estimated value F of the full charge capacity F EST [%] and the overall relationship of the voltage error ΔE [V]. In the ternary lithium-ion secondary battery 10, for example, as Figure 2 shown, a positive correlation is shown in a part of the low SOC region (here less than 25 [%]), and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. In addition, a negative correlation is shown in the region of SOC [%] larger than that (here 25 [%] or more and less than 35 [%]), and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is slightly smaller. And in a relatively high SOC region (here 35 [%] or more and less than 80 [%]), a positive correlation is shown over a long interval, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is moderate. And in a 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 is a graph showing the estimated SOC, i.e., S EST < true value F TRUE in the case of the estimated value F of the full charge capacity F EST [%] and the overall relationship of the voltage error ΔE [V]. As Figure 3As shown, for example, in a part of the low SOC region (here less than 20 [%]), a negative correlation is shown, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. Additionally, in a region with a larger SOC [%] (here 20 [%] or more and less than 35 [%]), 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. Also, in a relatively high SOC region (here 35 [%] or more and less than 80 [%]), a negative correlation is shown over a long interval, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is moderate. And in a high SOC region (here 80 [%] or more), a negative correlation is shown, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is small.

[0034] Here, in order to improve the estimation accuracy of the full charge capacity F in this embodiment, it is preferable to have a strong correlation and a sufficiently large change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%]. In addition, in Figure 2 the estimated value F of the full charge capacity F shown in EST > the true value F TRUE in the case of the estimated SOC, that is, S EST [%] and the relationship with the voltage error ΔE [V], and Figure 3 the estimated value F of the full charge capacity F shown in EST < the true value F TRUE in the case of the estimated SOC, that is, S EST [%] and the relationship with the voltage error ΔE [V], it is preferable to satisfy all of the above conditions simultaneously.

[0035] From such a perspective, first, Figure 2 the region less than 25 [%] of Figure 3 and the region less than 20 [%] of

[0036] both have a strong correlation, and the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. Therefore, it can be known that the region where the estimated SOC [%] is less than 20 [%], which is their common region, is a common region suitable for the estimation of the full charge capacity F. Figure 2 the region 35 [%] or more and less than 80 [%] of Figure 3 and the region 35 [%] or more and less than 80 [%] of

[0037] Here, in the present embodiment, the in-vehicle drive lithium-ion secondary battery 10 is exemplified as the object of the method for estimating the full charge capacity F. As described above, in the region where the estimated SOC [%] is less than 20 [%], the change in the voltage error ΔE [V] with respect to the change in the estimated SOC [%] is large. Therefore, the region where the estimated SOC [%] is less than 20 [%] can be said to be a region suitable for the method for estimating the full charge capacity F. However, the preferable usage range of the SOC [%] of the in-vehicle drive lithium-ion secondary battery 10 such as in the present embodiment can be exemplified as, for example, 20 to 80 [%]. In the method for estimating the full charge capacity F of the present embodiment, it is preferable to implement in the usage range of the SOC [%] that is usually used. Therefore, in the present embodiment, it is implemented in the region where the estimated SOC [%] is 35 [%] or more and less than 80 [%]. Further considering the individual differences of the lithium-ion secondary battery 10, etc., leaving a margin for safety, the method for estimating the full charge capacity F of the present embodiment is implemented when it is 40 [%] or more and less than 70 [%].

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

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

[0040] As Figure 6 shown, the lithium-ion secondary battery 10 is configured in the form of unit cells that constitute a battery module 10A (refer to Figure 8 ). The lithium-ion secondary battery 10 includes a plate-shaped rectangular parallelepiped battery case 11 having an opening portion on the upper side. An electrode body 12 is housed inside the battery case 11. A non-aqueous electrolyte 13 is filled into the battery case 11 from a liquid injection hole. The battery case 11 is made of a metal such as aluminum alloy and constitutes an electrolytic cell sealed with a lid body. In addition, the lithium-ion secondary battery 10 includes a positive electrode external terminal 14 and a negative electrode external terminal 15 for charging and discharging electric 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 body. In addition, 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 body. The positive electrode current collector terminal 16 is connected to the positive electrode current collecting portion 33 of the electrode body 12 (refer to Figure 7)electrically connected. In addition, the negative electrode current collector terminal 17 is electrically connected to the negative electrode current collecting portion 23 of the electrode body 12 (see Figure 7 )electrically connected.

[0041] <Electrode body 12> Figure 7 is a schematic diagram showing the structure of the wound electrode body 12. In the electrode body 12, a plurality of negative electrode plates 2, positive electrode plates 3, and separators 4 disposed therebetween are laminated. The laminated negative electrode plates 2, positive electrode plates 3, and separators 4 are wound and formed into a flat shape. The negative electrode plate 2 forms a negative electrode composite material layer 22 on a negative electrode current collector 21 made of copper foil as a base material. A negative electrode current collecting portion 23 is provided on one end side in the width direction W (winding axis direction) orthogonal to the winding direction L. The negative electrode current collecting portion 23 has a structure in which the negative electrode composite material layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0042] The positive electrode plate 3 forms a positive electrode composite material layer 32 on a positive electrode current collector 31 made of aluminum foil as a base material. As Figure 7 shown, a positive electrode current collecting portion 33 is provided on the other end side (the side opposite to the negative electrode current collecting portion 23) in the width direction W (winding axis direction) orthogonal to the winding direction L in which the positive electrode current collector 31 is wound. The positive electrode current collecting portion 33 has a structure in which the positive electrode composite material layer 32 is not formed and the metal of the positive electrode current collector 31 is exposed.

[0043] <Laminated structure of electrode body 12> As Figure 7 shown, the basic structure of the electrode body 12 of the 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 has negative electrode composite material layers 22 on both sides of a negative electrode current collector 21 as a negative electrode base material. One end portion of the negative electrode current collector 21 becomes a negative electrode current collecting portion 23 where the metal is exposed. The positive electrode plate 3 has positive electrode composite material layers 32 on both sides of a positive electrode current collector 31 as a positive electrode base material. The other end portion of the positive electrode current collector 31 becomes a positive electrode current collecting portion 33 where the metal is exposed.

[0045] The negative electrode plate 2 and the positive electrode plate 3 are overlapped with each other with a separator 4 interposed therebetween to form a laminate. As Figure 1 shown, the laminate is wound around the winding axis in the longitudinal direction to form Figure 7 a wound type electrode body 12 which is formed into a flat shape as shown.

[0046] <Non-aqueous electrolyte 13> Figure 6As shown, the non-aqueous electrolyte 13 of the lithium ion secondary battery 10 of the present embodiment is impregnated in the electrode body 12. The non-aqueous electrolyte 13 is a composition obtained by dissolving a lithium salt in an organic solvent. As the lithium salt, LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 etc. As the organic solvent, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, and dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane, sulfur-containing compounds such as ethyl methyl sulfone and butane sultone, or phosphorus compounds such as triethyl phosphate and trioctyl phosphate can be mentioned. As the non-aqueous electrolyte 13, one or more of them can be used in combination. It should be noted that the composition of the non-aqueous electrolyte 13 is not limited thereto.

[0047] <Constituent elements of the electrode body 12> Next, the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are the constituent elements of the electrode body 12, will be described.

[0048] <Negative electrode plate 2> As Figure 7 shown, a negative electrode composite layer 22 is formed on both sides of the negative electrode current collector 21 as the negative electrode substrate to form the negative electrode plate 2. The negative electrode composite layer 22 is formed by applying a negative electrode composite paste to the negative electrode current collector 21. Thereafter, the negative electrode plate 2 is completed through a drying process, a pressing process, and a cutting process.

[0049] <Negative electrode current collector 21> Regarding the negative electrode current collector 21, in the present embodiment, it is composed of a Cu foil. The negative electrode current collector 21 constitutes the base of the aggregate of the negative electrode composite layer 22 and has the function of a current collecting component that collects electricity from the negative electrode composite layer 22. One end portion of the negative electrode current collector 21 is not formed with the negative electrode composite layer 22 and becomes a negative electrode current collecting portion 23 where the metal surface is exposed. That is, 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 portion 23, and the negative electrode current collecting terminal 17.

[0050] <Negative electrode composite layer 22> In the present embodiment, the negative electrode active material is a powdery carbon material composed of graphite (graphite) having a layered structure or the like, and is a material capable of occluding and releasing lithium ions Li + .

[0051] <Positive electrode plate 3> AsFigure 7 As shown, the positive electrode plate 3 is composed of a positive electrode current collector 31 as a positive electrode base material and a positive electrode composite material layer 32 coated on the positive electrode current collector 31. The positive electrode composite material layer 32 is formed by coating a positive electrode composite material paste on the positive electrode current collector 31. Subsequently, through a drying process, a pressing process, and a cutting process, the positive electrode plate 3 is completed.

[0052] <Positive electrode current collector 31> The positive electrode plate 3 is formed by forming the positive electrode composite material layer 32 on both sides of the positive electrode current collector 31 as a positive electrode base material. In the embodiment, the positive electrode current collector 31 is composed of an Al foil. The positive electrode current collector 31 constitutes the base of the aggregate of the positive electrode composite material layer 32 and has the function of a current collecting component for collecting electricity from the positive electrode composite material layer 32.

[0053] First, regarding the positive electrode base material constituting the positive electrode current collector 31, an Al foil is exemplified. For example, it is composed of a conductive material (formed of a metal with good conductivity). As a material with good conductivity, for example, in addition to the Al foil, a material containing an Al alloy can also be used. The constitution of the positive electrode current collector 31 is not limited to this.

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

[0055] <Composition of the 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, in addition to Li, one or more specified transition metal elements. 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 can exemplify a so-called ternary system material having a lithium transition metal oxide containing all elements of Ni, Co, and Mn, which is called NCM.

[0056] It should be noted that the positive electrode active material of this embodiment is not limited to a material having a lithium transition metal oxide containing all elements of Ni, Co, and Mn. In addition, the positive electrode active material can have a composition containing, for example, Al in addition to them. In addition, the positive electrode active material can be LiMnO 4 、LiFePO 4 and so on.

[0057] <Separator 4> The separator 4 is a non-woven fabric made of polypropylene or the like, which is a porous resin and has high insulation properties for holding the non-aqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. In addition, as the separator 4, porous polymer membranes such as porous polyethylene membranes, porous polyolefin membranes, and porous polyvinyl chloride membranes, or lithium-ion or ion-conductive polymer electrolyte membranes can be used alone or in combination.

[0058] <Overall Configuration of a Vehicle Equipped with a Secondary Battery> Figure 8 It is a block diagram showing an example of the configuration of a vehicle 1 using a lithium-ion secondary battery 10 in the implementation stage. Figure 8 The exemplified vehicle 1 is a hybrid vehicle. The vehicle 1 includes a control device 20 that also functions as an estimated full charge capacity device for the lithium-ion secondary battery 10, a power control unit (PCU: Power Control Unit) 30, motor generators 41, 42, an engine 50, a power distribution device 60, a drive shaft 70, and drive wheels 80. The control device 20 of the lithium-ion secondary battery 10 in the present embodiment includes a battery module 10A, a monitoring unit 40, and an ECU (electronic control unit: 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 burns into the kinetic energy of moving parts such as pistons and rotors.

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

[0061] The motor generators 41, 42 are respectively AC rotating motors, for example, three-phase AC synchronous motors in which permanent magnets (not shown) are embedded in the rotors. The motor generator 41 is mainly used as a generator driven by the engine 50 via the power distribution 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] The motor generator 42 mainly operates as a motor to drive the drive wheels 80. The motor generator 42 is driven by receiving at least one of the electric power from the lithium-ion secondary battery 10 and the electric power generated by the motor generator 41, and the driving force of the motor generator 42 is transmitted to the drive shaft 70. On the other hand, during braking of the vehicle or when the acceleration on a downhill slope decreases, the motor generator 42 operates as a generator to perform regenerative power generation. The electric power generated by the motor generator 42 is supplied to the battery module 10A via the PCU 30.

[0063] The battery module 10A is composed of a plurality of lithium ion secondary batteries 10 as unit cells. The lithium ion secondary batteries 10 store electric power for driving the electric generators 41 and 42, and supply the electric power to the electric generators 41 and 42 through the PCU 30. Further, when the electric generators 41 and 42 generate electricity, the lithium ion secondary batteries 10 receive the generated electricity through the PCU 30 and are charged.

[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 the present embodiment detects, for example, the voltage E of each unit cell of the lithium ion secondary battery 10. However, it is also possible to detect the voltage E of the entire battery module 10A composed of a plurality of battery cells of the lithium ion secondary batteries 10 connected in parallel to each other. In this case, the voltage of each unit cell is estimated from the overall voltage. The current measuring device 40b detects the current I input to and output 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] It should be noted that the monitoring units of the voltage measuring device 40a and the temperature measuring device 40c are not limited to each unit cell of the lithium ion secondary battery 10, and may also be each block, or each unit cell of a plurality of (a number less than the number of battery cells in a block) adjacent lithium ion secondary batteries 10. In the present embodiment, the internal configuration of the lithium ion secondary battery 10 has no particular influence, and it is also possible not to distinguish between the unit cells of the plurality of lithium ion secondary batteries 10 and not to distinguish between the plurality of blocks. Therefore, hereinafter, the monitoring unit is regarded as the lithium ion secondary battery 10, and is collectively described as "detecting the voltage E of the lithium ion secondary battery 10" and the like.

[0066] The PCU 30 performs two-way power conversion between the lithium ion secondary battery 10 and the electric generators 41 and 42 according to a control signal from the ECU 100. The PCU 30 is configured to be able to control the states of the electric generators 41 and 42 respectively. For example, the electric generator 41 can be set to a regenerative state (power generation state), and the electric generator 42 can be set to a power running state. The PCU 30 is provided corresponding to the electric generators 41 and 42, for example. It is composed of two inverters and a converter (both not shown) that boosts the DC voltage supplied to each inverter to a voltage higher than the output voltage of the lithium ion secondary battery 10.

[0067] <ecu100> In this embodiment, the ECU 100 of the control device 20 serves as a part that controls as a 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 ROM (Read Only Memory) and a RAM (Random Access Memory). In addition, the memory 102 has a storage medium such as an EPROM (erasable programmable read only memory), an SSD (Solid State Drive), or an HDD (Hard Disc Drive) that stores programs, maps, etc. The ECU 100 controls the engine 50 and the PCU 30 based on the signals received from each measuring device and the programs and maps stored in the memory 102, thereby controlling the charging and discharging of the lithium-ion secondary battery 10.

[0069] Figure 9 It is a block diagram showing a part of the program stored in the memory 102. As Figure 9 shown, a program that causes the CPU 101 to function as a current measurement unit 102a is stored in the memory 102. 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 offset direction calculation unit 102h, and a parameter correction unit 102i are stored.

[0070] <Flowchart of the full charge capacity estimation method for the lithium-ion secondary battery in this embodiment> Figure 10 It is a flowchart showing an example of the process of the full charge capacity estimation method for the secondary battery in this embodiment.

[0071] Since the full charge capacity estimation method for the secondary battery is performed within a specified SOC range (40 to 70 [%] in this embodiment), as a prerequisite, it is determined whether the estimated SOC value is within the specified range (S1).

[0072] Here, as the step of current measurement, the current I [A] flowing in the lithium-ion secondary battery can be obtained by Figure 8 The current measurement device 40b of the monitoring unit 40 shown performs real-time measurement. Here, the estimated SOC, which is defined as S EST , the full charge capacity F, and the current ΣI [Ah] accumulated from the current I [A], ΣI [Ah]=∫Idt. In the present embodiment, as a step of SOC estimation, the estimated SOC, which is S EST [%] is obtained based on the current integration method. Specifically, as a step of SOC estimation, the estimated SOC, which is S EST [%] is obtained using "(1 / full charge capacity F)×∫Idt" used in the current ΣI [Ah] accumulated from the current I [A]. The obtained estimated SOC, which is S EST [%] is stored in the memory 102. Here, if the estimated SOC, which is S EST [%] is not within the specified range (40 [%] or more to 70 [%] or less in the present embodiment), the process ends and returns to the process of S1 again. If the estimated SOC, which is S EST [%] is within the specified range, after performing the following process, it proceeds to the step (S2) of "Is it the data saving timing?".

[0073] On the other hand, before data saving, the following process is performed in parallel with the step of SOC estimation. Figure 11 is a diagram showing the equivalent circuit of the lithium ion secondary battery 10 of the present embodiment. In the present invention, the method for estimating SOC is not limited. As an example of SOC estimation, a method for estimation based on a battery model can be used. The equivalent circuit of the lithium ion secondary battery 10 can be as Figure 11 shown by a resistor R 0 , and a parallel circuit of a resistor R 0 connected in series with this resistor R 1 and a capacitor C 1 . Such an equivalent circuit is determined, for example, by complex AC impedance measurement to determine the values of the resistor R 0 , the resistor R 1 , and the capacitor C 1 . And the combined resistance of the entire equivalent circuit can be obtained.

[0074] As a step of voltage estimation, based on the combined resistance of the entire equivalent circuit and the current I [A] or the voltage of the equivalent circuit, which is the estimated voltage E EST [V], is stored in the memory 102. In addition, at the same time, through the step of voltage measurement, the voltage of the lithium ion secondary battery 10 is measured using the Figure 8 voltage measurement device 40a of the monitoring unit 40 shown, and the measured voltage E DATA [V] is stored in the memory 102.

[0075] And, as a step of calculating the voltage error ΔE, according to "voltage error ΔE [V] = measured voltage E DATA [V] - estimated voltage E EST [V]", calculate the voltage error ΔE [V] and store it in the memory 102.

[0076] As a step of storing SOC·voltage error, if it is a specified timing (for example, the interval of data saving timing is 0.1 [sec]) (S2: Yes), then proceed to the process of saving the estimated SOC and the voltage error (S3). If it is not the specified timing (S2: No), then end the process and return to the process of S1.

[0077] If it is determined to be the data saving timing (S2: Yes) in the process of "Is it the data saving timing?" (S2), then save the calculated estimated SOC, that is, S EST [%] and the voltage error ΔE [V] in the memory 102.

[0078] If the number of data of the estimated SOC, that is, S EST [%] and the voltage error ΔE [V] saved in the process of saving the estimated SOC and the voltage error (S3) does not reach the specified number (for example, more than 50) (S4: No), then end the process and return to the process of S1.

[0079] If the number of data of the estimated SOC, that is, S EST [%] and the voltage error ΔE [V] saved in the process of saving the estimated SOC and the voltage error (S3) reaches the specified number or more (S4: Yes), then proceed to the process of calculating the slope of the approximate straight line (S5).

[0080] <Calculating the slope of the approximate straight line (S5)> In the calculation of the slope of the approximate straight line (S5), as a step of calculating the straight line, plot multiple groups of the estimated SOC, that is, S EST [%] and the voltage error ΔE [V] in the Figure 4 or Figure 5 coordinates. And perform multiple regression analysis, etc. on multiple data points P to calculate an approximate straight line as ΔE = a(Sest) + b (where a is the slope and b is the intercept).

[0081] This approximate straight line is Figure 4 the graph L 1 like a graph that descends to the right, or Figure 5 the graph L 2 like a graph that rises to the right. Here, as a step of calculating the full charge capacity estimation offset direction, obtain the slope a. Figure 4 the graph L 1 In a graph that slopes downward to the right like that, the slope a is negative. Additionally, Figure 5 graph L 2 In a graph that slopes upward to the right like that, the slope a is positive.

[0082] In the process of "Is the calculated slope positive?" (S6), when the slope a calculated in the process of calculating the slope of the approximate straight line (S5) is positive (S6: Yes), the process advances to the process of correcting the parameter in the direction of decreasing the full charge capacity F (S7). When the slope a calculated in the process of calculating the slope of the approximate straight line (S5) is negative (S6: No), the process advances to the process of correcting the parameter in the direction of increasing the full charge capacity F (S8).

[0083] In the process of correcting the parameter in the direction of decreasing the full charge capacity F (S7), the CPU 101 executes the program stored in the parameter correction unit 102i. Regarding the step of correcting the average negative electrode Li ion concentration [%] as a step of parameter correction, the CPU 101 corrects a fixed value each time in the direction of decreasing the average negative electrode Li ion concentration [%] so that the slope a approaches zero. When the CPU 101 has corrected the average negative electrode Li ion concentration [%] once, it calculates the slope a again, and after correcting the average negative electrode Li ion concentration [%] in such a way that the slope a is closest to zero, the process of correction (S7) ends.

[0084] Regarding correcting the parameter in the direction of increasing the full charge capacity F (S8), the CPU 101 also executes the program stored in the parameter correction unit 102i. Regarding the step of correcting the average negative electrode Li ion concentration [%] as a step of parameter correction, the CPU 101 corrects a fixed value each time in the direction of increasing the average negative electrode Li ion concentration [%] so that the slope a approaches zero. When the CPU 101 has corrected the average negative electrode Li ion concentration [%] once, it calculates the slope a again, and after correcting the average negative electrode Li ion concentration [%] in such a way that the slope a is closest to zero, the process of correction (S8) ends.

[0085] After the process of correcting the parameter in the direction of decreasing the full charge capacity F (S7) or the process of correcting the parameter in the direction of increasing the full charge capacity F (S8) described above ends, the process of the method for estimating the full charge capacity F of the secondary battery of the present embodiment is temporarily ended. Additionally, the process is restarted at a specified timing, such as after a certain time, a certain traveling distance, etc.

[0086] (Function of the present embodiment) In the method for estimating the full charge capacity using the full charge capacity estimating device of the secondary battery of the present embodiment, only the current I [A] of the lithium ion secondary battery 10 is directly measured to estimate the voltage E EST [V] and the estimated SOC, that is, S EST [%] is estimated. Further, by measuring the measured voltage E DATA [V] directly and subtracting the estimated voltage E EST [V], the voltage error ΔE [V] is obtained. Then, based on the estimated SOC, i.e., S EST [%], it is determined whether the estimated value F of the full charge capacity F EST [Ah] is too large or too small. And when it is too small, the estimated value F of the full charge capacity F EST [Ah] is corrected in the direction of increasing it, and conversely, when it is too large, the estimated value F of the full charge capacity F EST [Ah] is corrected in the direction of decreasing it. By accurately correcting the estimated value F of the full charge capacity F EST [Ah] in this way, the estimated SOC, i.e., S EST [%] can also be accurately estimated, and control matching the characteristics of the lithium-ion secondary battery 10 as the object can be performed. As a result, the performance of the lithium-ion secondary battery 10 as the object can be maximally obtained, and its deterioration can be effectively suppressed.

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

[0088] Figure 12 (a) shows the estimated voltage E DATA [V] with respect to the measured voltage E EST [V] over time. The horizontal axis represents the passage of time [s], and the vertical axis represents the voltage [V]. The measured voltage E DATA [V] is represented by a dotted line, and the estimated voltage E EST [V] is represented by a solid line. Figure 12 In (a), the dotted line representing the measured voltage E DATA [V] and the solid line representing the estimated voltage E EST [V] almost overlap and are difficult to distinguish.

[0089] Figure 12 (b) is a graph showing the voltage error ΔE [V] over time. That is, the estimated voltage E is subtracted from the measured voltage E DATA [V] EST [V]. Figure 12 In (a), the difference is difficult to distinguish, but in Figure 12 In (b), it can be seen that the voltage error ΔE is initially approximately 0.025 [V], but when approximately 5000 [s] have elapsed, the curve (graph) contracts to approximately 0.00 [V].

[0090] Figure 12 In (c), it shows the estimated SOC, i.e., S TRUE [%] with respect to the true value of SOC, S EST [%] over time. The vertical axis represents SOC [%]. The true value of SOC, S TRUE [%] represented by the dashed line is the value obtained by integrating the input current derived from strict observations and can be regarded as the true value of SOC [%]. In contrast, the estimated SOC, i.e., S EST [%] represented by the solid line is the value estimated by the full charge capacity estimation method of this embodiment using a battery model based on voltage. There is a deviation before approximately 5000 [s] have elapsed, but afterwards the graphs overlap and it is difficult to distinguish.

[0091] Figure 12 In (d), it shows the SOC error ΔS [%] over time. The vertical axis represents the SOC error ΔS [%] obtained by subtracting the estimated SOC, i.e., S TRUE [%] from the SOC, i.e., the true value of SOC, S EST [%]. Figure 12 In (d), it can be seen that initially there is an error of approximately -8 [%] to +3 [%], but when approximately 5000 [s] have elapsed, the curve contracts to approximately 0 [%].

[0092] Figure 12 In (e), it shows the estimated value of the full charge capacity F TRUE [Ah] with respect to the true value of the full charge capacity F EST [Ah] over time. The vertical axis represents the full charge capacity F [Ah]. The true value of the full charge capacity F TRUE [Ah] represented by the dashed line is the value of the full charge capacity F [Ah] regarded as the true value derived from strict observations. The solid line represents the estimated value of the full charge capacity F EST [Ah]. Here, similar to Figure 12 the voltage error ΔE [V] shown in (b), Figure 12 and the SOC error ΔS [%] shown in (d), with respect to the true value of the full charge capacity F TRUE [Ah] represented by the dashed line, the initial estimated value F EST [Ah] represented by the solid line has a deviation before approximately 5000 [s] have elapsed. When approximately 5000 [s] have elapsed, it can be seen that the deviation contracts to approximately 0 [Ah].

[0093] Based on the above experimental results, it is confirmed that the full charge capacity estimation method of this embodiment is extremely stable and can accurately estimate the full charge capacity F. (Effect of this embodiment) (1) The full charge capacity estimation method and the full charge capacity estimation device of the lithium ion secondary battery 10 according to this embodiment have the effect of being able to easily estimate the full charge capacity F of the lithium ion secondary battery 10.

[0094] (2) Therefore, it has the effect of maximizing the performance of the lithium ion secondary battery 10 as the object and being able to effectively suppress its deterioration. (3) Derive a straight line ΔE = a(S EST [%]) + b (where a is the slope and b is the intercept) representing the relationship between the voltage error ΔE [V] and the estimated SOC, that is, S EST ). And, based on the slope a of the derived straight line, calculate the estimated value F EST representing the full charge capacity F [Ah] and the size relationship between the true value F TRUE of the full charge capacity [Ah]. Therefore, by using the voltage error ΔE [V] and the estimated SOC, that is, S EST [%], it has the effect of being able to accurately estimate the estimated value F EST and the full charge capacity F [Ah].

[0095] (4) Both the voltage error ΔE [V] and the estimated SOC, that is, S EST [%] can be calculated only by measuring the voltage E and current I of the lithium ion secondary battery 10. Therefore, it has the effect of being able to easily perform the calculation by using the existing control device 20 of the lithium ion secondary battery 10 without the need for a new device or the like.

[0096] (5) In addition, instead of the full charge capacity estimated value F EST [Ah], parameters used in the control of the lithium ion secondary battery 10, such as the average Li ion concentration [%] of the negative electrode, can be corrected. Thus, it has the effect of being able to easily optimize the control of the lithium ion secondary battery 10.

[0097] (6) Additionally, it is performed in advance using an SOC (for example, 40 to 70 [%] in this embodiment) suitable for the full charge capacity estimation method of the lithium ion secondary battery 10 of this embodiment. Therefore, it has the effect of being able to further accurately estimate the full charge capacity F of the lithium ion secondary battery 10.

[0098] (7) If the data saving timing (S2) and the specified value of the data quantity (S4) are changed, it has the effect of being able to perform control more suitable for the lithium ion secondary battery 10 as the object.

[0099] (Other examples) · In this embodiment, as an example of the secondary battery, the unit cell of the lithium ion secondary battery 10 used for driving purposes in a hybrid vehicle or the like has been described, but the present invention is not limited thereto. For example, the secondary battery is not limited to a lithium ion secondary battery, and may also be other non-aqueous electrolyte secondary batteries, or solid state secondary batteries, alkaline secondary batteries such as nickel-metal hydride storage batteries, and the like.

[0100] · In addition, the purpose is not limited to vehicle driving purposes, and it can also be used as a stationary battery or a battery for portable devices. · In this embodiment, the lithium ion secondary battery 10 as a unit cell (which constitutes the battery module 10A as a battery pack) is exemplified, and it can be a method of controlling using a single unit cell, or a method of a battery pack having a plurality of battery modules. In this case, in the measurement of the current I [A] and the voltage E [V], the unit cell can be directly measured, or the battery pack can be used for measurement.

[0101] · In this embodiment, in the estimation of the full charge capacity F, the SOC is in the range of 40 to 70 [%], but it can also be implemented at 20 [%] or less. Further, it can be optimized by those skilled in the art according to the battery characteristics when using different positive electrode active materials so that it is, for example, 30 to 80 [%]. In addition, the full charge capacity F can be estimated without limiting the SOC [%] according to the characteristics of the battery.

[0102] · Regarding the data saving timing (S2) and the specified value (S4) of the data quantity, those skilled in the art can appropriately optimize them according to the battery characteristics, the capabilities of the control device 20, the amount of noise or deviation, and the like.

[0103] · Regarding the estimated voltage E EST [V], the estimated SOC, that is, S EST [%], in this embodiment, the same type of lithium ion secondary battery is measured by complex impedance measurement or the like, and is estimated by Ohm's law or the like using the Figure 11 shown equivalent circuit, but is not limited thereto. For example, it can be estimated by using a detailed Newman model of a diffusion type or the like.

[0104] · In this embodiment, the voltage error ΔE [V] is obtained by voltage error ΔE [V]=measured voltage E DATA -estimated voltage E EST However, it can also be obtained by voltage error ΔE [V]=estimated voltage E EST -measured voltage E DATA In this case, the sign of the slope a is reversed.

[0105] · The estimated full charge capacity F EST can be further corrected using a Kalman filter or the like. · In this embodiment, instead of correcting the estimated value F of the full charge capacity F EST the "average Li ion concentration of the negative electrode", which is a control parameter, is corrected. The parameter is not limited to this, and other parameters that can be used for the control of the secondary battery can also be corrected.

[0106] · The numerical values, numerical ranges, etc. of this embodiment are given as an example, but are not limited to this. Those skilled in the art can appropriately optimize and implement according to the battery characteristics. · Figure 10 The flowchart shown is an example for illustrative implementation, but is not limited to this. Those skilled in the art can implement by adding, deleting, replacing, and changing the process.

[0107] · As long as the scope of the claims is not departed from, of course, those skilled in the art can implement by adding, deleting, or changing the configuration of the present invention.

Claims

1. A method for estimating the full charge capacity of a secondary battery, characterized in that: It has the following steps: An SOC estimating step of estimating an estimated SOC of a target secondary battery; The voltage estimation procedure is to estimate the voltage E EST Make a presumption; The voltage measurement step is to measure the voltage E of the secondary battery. DATA Conduct measurement; The voltage error ΔE calculation step calculates the estimated voltage E EST The measured voltage E measured at the same time DATA The voltage difference is the voltage error ΔE; an estimated SOC·voltage error storage step of storing a plurality of value sets of the voltage error ΔE and the estimated SOC at the same time at different times; The step of calculating a straight line is to derive a straight line ΔE=a(S EST )+b, where S EST is the estimated SOC, a is the slope, b is the intercept, and the voltage error ΔE is derived from a plurality of value groups stored at the change timing in the step of storing the estimated SOC·voltage error; as well as A step of calculating a full charge capacity estimation deviation direction, calculating an estimated value F representing the full charge capacity F based on the slope a of the straight line derived in the straight line calculation step. EST and the true value F of the full charge capacity F TRUE The full charge capacity is estimated to shift in the direction ΔF based on the magnitude relationship.

2. The method for estimating the full charge capacity of a secondary battery according to claim 1, characterized in that: The steps of SOC estimation include: a current measuring step of measuring the current I flowing through the secondary battery; as well as The voltage estimation step includes estimating the voltage E based on the current I and the internal resistance R of the secondary battery based on the battery model. EST Make an inference, The estimated SOC of the secondary battery is estimated based on the accumulated current I, ie, current ΣI.

3. The method for estimating the full charge capacity of a secondary battery according to claim 1, characterized in that: The method comprises a step of correcting the full charge capacity estimation value, wherein the full charge capacity estimation deviation direction ΔF calculated in the step of calculating the full charge capacity estimation deviation direction is corrected according to the straight line ΔE=a(S EST )+b becomes horizontal, the estimated value F of the full charge capacity F EST Make corrections.

4. The method for estimating the full charge capacity of a secondary battery according to claim 1, characterized in that: The method comprises a parameter correction step, wherein the full charge capacity estimation deviation direction ΔF calculated in the full charge capacity estimation deviation direction calculation step is calculated according to the straight line ΔE=a(S EST The parameters used in controlling the secondary battery are corrected so that the slope a of )+b becomes horizontal.

5. The method for estimating the full charge capacity of a secondary battery according to claim 4, characterized in that: The parameter correction step includes 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.

6. The method for estimating the full charge capacity of a secondary battery according to claim 5, characterized in that: In the step of correcting the negative electrode average Li ion concentration, the estimated value of the negative electrode average Li ion concentration is corrected by a fixed value in a direction in which the estimated deviation of the full charge capacity estimation deviation direction ΔF decreases until the slope a reverses in sign.

7. The method for estimating the full charge capacity of a secondary battery according to claim 1, characterized in that: The SOC estimating step includes an SOC determining step, and a method for estimating a full charge capacity of a secondary battery is executed only when the estimated SOC value of the secondary battery is within a preset SOC range.

8. The method for estimating the full charge capacity of a secondary battery according to claim 1, characterized in that: The secondary battery is a lithium ion secondary battery.

9. The method for estimating the full charge capacity of a secondary battery according to claim 7, characterized in that: The secondary battery is a ternary lithium-ion secondary battery. The predetermined SOC range is set within a range of 40% to 70%.

10. A device for estimating the full charge capacity of a secondary battery, comprising: DATA A voltage measuring device for measuring, a current measuring device for measuring the current I of the secondary battery, and a device for obtaining the voltage E DATA The device for estimating the full charge capacity of a secondary battery of a computer for estimating the full charge capacity F of the secondary battery using the current I is characterized in that: The computer has: An SOC estimating unit estimates an estimated SOC of the secondary battery; The voltage estimation unit estimates the voltage E EST Make a presumption; The voltage measuring unit measures the voltage E of the secondary battery. DATA Conduct measurement; The SOC voltage error storage unit stores a plurality of value sets of a voltage error ΔE and the estimated SOC at the same time at different times, wherein the voltage error ΔE is a value of the voltage E EST With the voltage E DATA difference; The straight line calculation unit derives a straight line ΔE=a(S EST )+b, where S EST In order to estimate the SOC, a is the slope, b is the intercept, and the voltage error ΔE is derived from a plurality of value groups stored at the change timing in the SOC·voltage error storage unit; as well as A full charge capacity estimation deviation direction calculation unit calculates an estimation value F indicating the full charge capacity F based on the slope a of the straight line derived in the straight line calculation unit. EST and the true value F of the full charge capacity F TRUE The full charge capacity is estimated to shift in the direction ΔF based on the magnitude relationship.

11. The device for estimating full charge capacity of a secondary battery according to claim 10, wherein: The SOC estimating unit includes: a current measuring unit for measuring a current I flowing through the secondary battery; and The voltage estimating unit estimates the voltage E based on the current I and the internal resistance R of the secondary battery based on a battery model. EST Make an inference, The estimated SOC of the secondary battery is estimated based on the accumulated current I, ie, current ΣI.

12. The device for estimating full charge capacity of a secondary battery according to claim 11, wherein: The device comprises a full charge capacity estimation value correction unit, which calculates the full charge capacity estimation deviation direction ΔF calculated by the full charge capacity estimation deviation direction calculation unit according to the straight line ΔE=a(S EST )+b becomes horizontal, the estimated value F of the full charge capacity F EST Make corrections.

13. The device for estimating full charge capacity of a secondary battery according to claim 11, wherein: The device comprises a parameter correction unit, which corrects the full charge capacity estimation deviation direction ΔF calculated by the full charge capacity estimation deviation direction calculation unit according to the straight line ΔE=a(S EST The parameters used in controlling the secondary battery are corrected so that the slope a of )+b becomes horizontal.

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