WO2021220492A1 - Secondary battery control system, battery pack, and secondary battery control method - Google Patents

Abstract

This secondary battery control system corrects the SoC of a secondary battery into N that is obtained by formula (1), where, in a V-dQ/dV curve that shows the relationship between the charging voltage of the secondary battery and dQ/dV which is the ratio of the amount of change in power storage level to the amount of change in the charging voltage of the secondary battery, a first point is the initial extremum point which appears within the range where the voltage V of the secondary battery is not less than 3.34 V to less than 3.38 V and at which the curve stops increasing and starts decreasing, a second point is the final extremum point which appears within the range where the voltage V of the secondary battery is 3.35-3.39 V and at which the curve stops decreasing and starts increasing, a third point is the initial extremum point which appears within the range where the voltage V of the secondary battery is 3.38-3.42 V and at which the curve stops increasing and starts decreasing, and ΔQ is the difference between the charge level Q_1st at the first point and the charge level Q_2nd at the second point. With the present invention, it is possible to improve the safety of a secondary battery, contribute to the stable supply of energy, and contribute to the achievement of the Sustainable Development Goals. (1): N=SoC{(dQ/dV_3rd)/Q_f-ΔQ*A} In formula (1), dQ/dV_3rd represents the ratio of the amount of change in the charge level to the amount of change in the voltage of the secondary battery at the third point, Q_f represents the full charge capacity of the secondary battery in the initial state, and A represents a number that satisfies 0.1≤A≤10.

Description

二次電池の制御システム、電池パック及び二次電池の制御方法Secondary battery control system, battery pack and secondary battery control method

　本発明は、二次電池の制御システム、電池パック及び二次電池の制御方法に関する。 The present invention relates to a secondary battery control system, a battery pack, and a secondary battery control method.

　二次電池の状態の指標としてＳＯＣ（State of Charge）やＳＯＨ（State of Health）が知られている。ＳＯＣは、二次電池の充電状態（残容量）を示す指標であり、ＳＯＨは電池の劣化状態を示す指標である。ＳＯＣは、満充電容量に対する残容量の割合である。ＳＯＨは、初期の満充電容量に対する劣化時の満充電容量の割合である。従来、二次電池のＳＯＣを推定する様々な方法が提案されている。 SOC (State of Charge) and SOH (State of Health) are known as indicators of the state of the secondary battery. SOC is an index showing the charge state (remaining capacity) of the secondary battery, and SOH is an index showing the deterioration state of the battery. SOC is the ratio of the remaining capacity to the fully charged capacity. SOH is the ratio of the fully charged capacity at the time of deterioration to the initial fully charged capacity. Conventionally, various methods for estimating the SOC of a secondary battery have been proposed.

　例えば、特許文献１には、二次電池の充放電電流を積算して充電状態を推定する方法が開示されている。また、特許文献２には、二次電池の開放電圧を検出し、当該開放電圧に基づいて充電状態を推定する方法が開示されている。 For example, Patent Document 1 discloses a method of estimating the charge state by integrating the charge / discharge currents of a secondary battery. Further, Patent Document 2 discloses a method of detecting an open circuit voltage of a secondary battery and estimating a charge state based on the open circuit voltage.

　一方、充放電電流の積算や開放電圧を用いない推定方法も提案されている。例えば、特許文献３には、電池電圧Ｖの変化量ｄＶに対する、二次電池の蓄電量Ｑの変化量ｄＱの割合であるｄＱ／ｄＶの特徴点を利用して二次電池の充電状態を推定する方法が開示されている。 On the other hand, an estimation method that does not use charge / discharge current integration or open circuit voltage has also been proposed. For example, in Patent Document 3, the state of charge of the secondary battery is estimated by using the feature point of dQ / dV, which is the ratio of the change amount dQ of the stored amount Q of the secondary battery to the change amount dV of the battery voltage V. The method of doing so is disclosed.

特許第５９８９３２０号公報Japanese Patent No. 5989320 特許３６６９２０２号公報Japanese Patent No. 3669202 特許６２９５８５８号公報Japanese Patent No. 6295858

　しかしながら、上記のような充放電電流の積算や開放電圧に基づく充電状態の推定方法では、依然として推定誤差が発生する。これは、電流センサや電圧センサの誤差が大きく、この誤差は満充電、満放電にならないとリセットできないため、満充電状態と満放電状態の間で推定を行う際に誤差をリセットすることができない。また、開放電圧は二次電池の劣化状態にも依存するため、推定精度の更なる低下が懸念される。 However, the estimation error still occurs in the charging state estimation method based on the charge / discharge current integration and the open circuit voltage as described above. This is because the error of the current sensor and the voltage sensor is large, and this error cannot be reset until it is fully charged and fully discharged. Therefore, the error cannot be reset when estimating between the fully charged state and the fully discharged state. .. Further, since the open circuit voltage depends on the deteriorated state of the secondary battery, there is a concern that the estimation accuracy will be further lowered.

　また、上記ｄＱ／ｄＶの特徴点を利用した充電状態の推定方法では、二次電池の個体差、劣化状態、環境温度等によって推定ＳＯＣにばらつきが生じる。例えば、充電曲線の特徴点は劣化状態によって変化し、また、高温劣化に因る変化の態様と低温劣化に因る変化の態様とは異なる。よって、充電曲線の特徴点を用いても二次電池の充電状態を高精度で推定することができない。 Further, in the charging state estimation method using the above-mentioned dQ / dV feature points, the estimated SOC varies depending on the individual difference of the secondary battery, the deterioration state, the environmental temperature, and the like. For example, the characteristic points of the charge curve change depending on the deterioration state, and the mode of change due to high temperature deterioration and the mode of change due to low temperature deterioration are different. Therefore, even if the feature points of the charge curve are used, the charge state of the secondary battery cannot be estimated with high accuracy.

　本発明は、上記問題に鑑みてなされたものであり、二次電池の充電状態を高精度で推定することができる二次電池の制御システム、電池パック及び二次電池の制御方法を提供することを目的とする。 The present invention has been made in view of the above problems, and provides a control system for a secondary battery, a battery pack, and a control method for the secondary battery, which can estimate the charge state of the secondary battery with high accuracy. With the goal.

　上記課題を解決するため、以下の手段を提供する。 To solve the above problems, the following means will be provided.

（１）第１の態様にかかる二次電池の制御システムは、二次電池の充電電圧と、前記二次電池の充電電圧の変化量に対する蓄電量の変化量の割合であるｄＱ／ｄＶとの関係を示すＶ－ｄＱ／ｄＶ曲線において、前記二次電池の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極大値若しくは前記極大値と数学的に等価な点を第１点とし、前記二次電池の電圧Ｖが３．３５Ｖ以上３．３９Ｖ以下の範囲内に現れる下降から上昇に転じる最後の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極小値若しくは前記極小値と数学的に等価な点を第２点とし、前記二次電池の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて３番目に現れる極大値若しくは前記極大値と数学的に等価な点を第３点とし、
　前記第１点における充電量Ｑ_１ｓｔと、前記第２点における充電量Ｑ_２ｎｄとの差をΔＱとし、
　前記二次電池のＳＯＣを、下記の式（１）で求められるＮへ補正する、二次電池の制御システム。
Ｎ＝ＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝　　　・・・（１）
　但し、式（１）において、ｄＱ／ｄＶ_３ｒｄは、前記第３点における前記二次電池の電圧の変化量に対する充電量の変化量の割合を表し、Ｑ_ｆは、前記二次電池の初期状態の満充電容量を表し、Ａは、０．１≦Ａ≦１０を満足する数を表す。 (1) The control system for the secondary battery according to the first aspect is a combination of the charging voltage of the secondary battery and dQ / dV, which is the ratio of the amount of change in the amount of electricity stored to the amount of change in the charging voltage of the secondary battery. In the V-dQ / dV curve showing the relationship, the voltage V of the secondary battery appears in the range of 3.34 V or more and less than 3.38 V, and is mathematically the first extreme point from rising to falling or the extreme point. The first point is the point equivalent to, the second maximum value that appears second from the low voltage side, or the point that is mathematically equivalent to the maximum value, and the voltage V of the secondary battery is 3.35V or more and 3.39V. The last extreme point that appears in the following range from falling to rising or a point that is mathematically equivalent to the extreme value point, or the minimum value that appears second from the low voltage side or the minimum value mathematically. The equivalent point is set as the second point, and the voltage V of the secondary battery is mathematically equivalent to the first extreme point or the extreme point that appears in the range of 3.38 V or more and 3.42 V or less and changes from rising to falling. The third point is the maximum value that appears third from the low voltage side or the point that is mathematically equivalent to the maximum value.
Let ΔQ be the difference between the charge amount Q _{1st at} the first point and the charge amount Q _{2nd at the second point.}
A secondary battery control system that corrects the SOC of the secondary battery to N obtained by the following formula (1).
N = SOC {(dQ / dV _3rd ) / Q _f −ΔQ * A} ・ ・ ・ (1)
However, in the formula (1), dQ / dV _3rd represents the ratio of the change amount of the charge amount to the change amount of the voltage of the secondary battery at the third point, and Q _f is the initial state of the secondary battery. Represents the full charge capacity of, and A represents a number satisfying 0.1 ≦ A ≦ 10.

（２）上記態様にかかる二次電池の制御システムにおいて、前記二次電池のＳＯＣの補正を、前記二次電池を満放電状態から充電した際の前記二次電池のＳＯＣと、前記二次電池の充電量Ｑを前記二次電池の電圧Ｖで微分して得たｄＱ／ｄＶとの関係を示すＳＯＣ－ｄＱ／ｄＶ曲線に基づいて行なってもよい。 (2) In the secondary battery control system according to the above aspect, the SOC of the secondary battery is corrected by the SOC of the secondary battery when the secondary battery is charged from a fully discharged state and the secondary battery. It may be performed based on the SOC−dQ / dV curve showing the relationship with dQ / dV obtained by differentiating the charge amount Q of the secondary battery with the voltage V of the secondary battery.

（３）上記態様にかかる二次電池の制御システムは、前記二次電池の充電量Ｑと前記二次電池の電圧Ｖとを検出する検出手段と、前記第１変曲点Ｐ２、前記第２変曲点Ｂ２及び前記第３変曲点Ｐ３を抽出する抽出手段と、前記第１変曲点Ｐ２における充電量Ｑ_Ｐ２と前記第２変曲点Ｂ２における充電量Ｑ_Ｂ２との差であるΔＱを算出すると共に、前記二次電池のＳＯＣを前記式（１）で求められるＮへ補正する補正手段と、を有していてもよい。 (3) The secondary battery control system according to the above aspect includes a detection means for detecting the charge amount Q of the secondary battery and the voltage V of the secondary battery, the first variation point P2, and the second. extracting means for extracting the inflection point B2 and the third inflexion point P3, Delta] Q is the difference between the charge amount _{Q B2} in the charging amount _{Q P2} second inflection point B2 in the first inflection point P2 And may have a correction means for correcting the SOC of the secondary battery to N obtained by the above formula (1).

（４）第２の態様にかかる電池パックは、二次電池と、上記態様に係る二次電池の制御システムとを備える。 (4) The battery pack according to the second aspect includes a secondary battery and a control system for the secondary battery according to the above aspect.

（５）第２の態様にかかる電池パックにおいて、前記二次電池は、正極と負極とを有し、前記正極は、活物質として、一般式ＬｉＦｅ_１－ＸＭ_ＸＰＯ_４で表されるリン酸鉄リチウム化合物を含み（但し、Ｍは、Ｍｎ，Ｃｒ，Ｃｏ，Ｃｕ，Ｎｉ，Ｖ，Ｍｏ，Ｔｉ，Ｚｎ，Ａｌ，Ｇａ，Ｍｇ，Ｂ，Ｎｂからなる群より選ばれる少なくとも一つの元素であり、ｘは、０≦Ｘ≦０．５を満たす数である）、前記負極は、活物質として黒鉛を含んでいてもよい。 (5) Phosphorus in the battery pack according to the second aspect, the secondary battery has a positive electrode and the negative electrode, the positive electrode, as an active material, represented by the general formula _{LiFe 1-X} M _X PO ₄ Contains a lithium iron acid compound (where M is at least one element selected from the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb. Yes, x is a number satisfying 0 ≦ X ≦ 0.5), and the negative electrode may contain graphite as an active material.

（６）第３の態様にかかる二次電池の制御方法は、二次電池の充電電圧と、前記二次電池の充電電圧の変化量に対する蓄電量の変化量の割合であるｄＱ／ｄＶとの関係を示すＶ－ｄＱ／ｄＶ曲線において、前記二次電池の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極大値若しくは前記極大値と数学的に等価な点を第１点とし、前記二次電池の電圧Ｖが３．３５Ｖ以上３．３９Ｖ以下の範囲内に現れる下降から上昇に転じる最後の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極小値若しくは前記極小値と数学的に等価な点を第２点とし、前記二次電池の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて３番目に現れる極大値若しくは前記極大値と数学的に等価な点を第３点とし、前記第１点における充電量Ｑ_１ｓｔと、前記第２点における充電量Ｑ_２ｎｄとの差をΔＱとし、前記二次電池のＳＯＣを、下記の式（１）で求められるＮへ補正する、二次電池の制御方法。
Ｎ＝ＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝　　　・・・（１）
　但し、式（１）において、ｄＱ／ｄＶ_３ｒｄは、前記第３点における前記二次電池の電圧の変化量に対する充電量の変化量の割合を表し、Ｑ_ｆは、前記二次電池の初期状態の満充電容量を表し、Ａは、０．１≦Ａ≦１０を満足する数を表す。 (6) The method for controlling the secondary battery according to the third aspect is dQ / dV, which is the ratio of the charge voltage of the secondary battery to the change amount of the stored amount with respect to the change amount of the charge voltage of the secondary battery. In the VdQ / dV curve showing the relationship, the voltage V of the secondary battery appears in the range of 3.34 V or more and less than 3.38 V, and the first extreme point from rising to falling or mathematically with the extreme point. The first point is the point equivalent to, the maximum value that appears second from the low voltage side, or the point that is mathematically equivalent to the maximum value, and the voltage V of the secondary battery is 3.35V or more and 3.39V. The last extreme point that appears in the following range from falling to rising or a point that is mathematically equivalent to the extreme value point, or the minimum value that appears second from the low voltage side or the minimum value mathematically. The equivalent point is set as the second point, and the voltage V of the secondary battery is mathematically equivalent to the first extreme point or the extreme point that appears in the range of 3.38 V or more and 3.42 V or less and changes from rising to falling. The third point is the maximum value that appears third from the low voltage side or the point that is mathematically equivalent to the maximum value, and the charge amount Q _{1st at} the first point and the charge at the second point. A method for controlling a secondary battery, wherein the difference from the quantity Q _2nd is ΔQ, and the SOC of the secondary battery is corrected to N obtained by the following formula (1).
N = SOC {(dQ / dV _3rd ) / Q _f −ΔQ * A} ・ ・ ・ (1)
However, in the formula (1), dQ / dV _3rd represents the ratio of the change amount of the charge amount to the change amount of the voltage of the secondary battery at the third point, and Q _f is the initial state of the secondary battery. Represents the full charge capacity of, and A represents a number satisfying 0.1 ≦ A ≦ 10.

　本発明によれば、二次電池の充電状態を高精度で推定することができる。また、ＳＯＣの高精度な推定に基づき、二次電池を効率よく充電させることができる。
　更に、本発明によれば、二次電池の安全性を高め、エネルギーの安定供給に寄与し、持続可能な開発目標に貢献することができる。 According to the present invention, the state of charge of the secondary battery can be estimated with high accuracy. In addition, the secondary battery can be efficiently charged based on the highly accurate estimation of the SOC.
Further, according to the present invention, it is possible to enhance the safety of the secondary battery, contribute to the stable supply of energy, and contribute to the sustainable development goal.

図１は、本発明の一実施形態にかかる電池パックのブロック図である。FIG. 1 is a block diagram of a battery pack according to an embodiment of the present invention. 図２は、本発明の一実施形態にかかる電池パックを用いて二次電池を充電したときの充電量Ｑと電圧Ｖの関係を示すＱ－Ｖ曲線を示すグラフである。FIG. 2 is a graph showing a QV curve showing the relationship between the charge amount Q and the voltage V when the secondary battery is charged using the battery pack according to the embodiment of the present invention. 図３は、図２のＱ－Ｖ曲線から算出したＶ－ｄＱ／ｄＶ曲線を示すグラフである。FIG. 3 is a graph showing a VdQ / dV curve calculated from the QV curve of FIG. 図４は、図３のグラフの極値点（Ｐ１）及び極地点（Ｂ１）付近を拡大して示すグラフである。FIG. 4 is an enlarged graph showing the vicinity of the extremum point (P1) and the extremum point (B1) in the graph of FIG. 図５は、図３のグラフの極値点（Ｐ２）、極値点（Ｂ２）及び極値点（Ｐ３）付近を拡大して示すグラフである。FIG. 5 is an enlarged graph showing the vicinity of the extremum point (P2), the extremum point (B2), and the extremum point (P3) in the graph of FIG. 図６は、図２のＱ－Ｖ曲線から算出したＳＯＣ－ｄＱ／ｄＶ曲線を示すグラフである。FIG. 6 is a graph showing the SOC−dQ / dV curve calculated from the QV curve of FIG. 図７（ａ）は、図５のグラフの極値点（Ｐ３）付近を拡大して示すグラフであり、図７（ｂ）は、ＳＯＣ補正の際に用いられるΔＱを示すグラフである。FIG. 7A is an enlarged graph showing the vicinity of the extreme value point (P3) in the graph of FIG. 5, and FIG. 7B is a graph showing ΔQ used at the time of SOC correction. 図８は、本発明の一実施形態にかかる電池パックにおいて用いることができる二次電池の断面図である。FIG. 8 is a cross-sectional view of a secondary battery that can be used in the battery pack according to the embodiment of the present invention. 図９は、本実施形態に係る二次電池の制御方法によって補正されたＳＯＣを検証する手順の一例を示すフローチャートである。FIG. 9 is a flowchart showing an example of a procedure for verifying the SOC corrected by the control method of the secondary battery according to the present embodiment.

　以下、実施形態について、図面を適宜参照しながら詳細に説明する。以下の説明で用いる図面は、特徴をわかりやすくするために便宜上特徴となる部分を拡大して示している場合があり、各構成要素の寸法比率等は実際とは異なっていることがある。以下の説明において例示される材料、寸法等は一例であって、本発明はそれらに限定されるものではなく、その要旨を変更しない範囲で適宜変更して実施することが可能である。 Hereinafter, the embodiment will be described in detail with reference to the drawings as appropriate. In the drawings used in the following description, the featured portion may be enlarged for convenience in order to make the feature easy to understand, and the dimensional ratio of each component may be different from the actual one. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

　図１は、本発明の一実施形態にかかる電池パックのブロック図である。図１に示すように、電池パック１００は、二次電池１０と、充電手段２０と、制御システム３０とを備える。二次電池１０と制御システム３０との間及び充電手段２０と制御システム３０との間では信号の通信が行われる。信号の通信は、有線でも無線でもよい。 FIG. 1 is a block diagram of a battery pack according to an embodiment of the present invention. As shown in FIG. 1, the battery pack 100 includes a secondary battery 10, a charging means 20, and a control system 30. Signal communication is performed between the secondary battery 10 and the control system 30 and between the charging means 20 and the control system 30. The signal communication may be wired or wireless.

　二次電池１０は、例えば、リチウムイオン二次電池である。二次電池１０の具体的な構成は後述する。二次電池１０は、１個であっても２個以上であってもよい。２個以上の二次電池は、直列に接続されていてもよいし、並列に接続されていてもよい。 The secondary battery 10 is, for example, a lithium ion secondary battery. The specific configuration of the secondary battery 10 will be described later. The number of secondary batteries 10 may be one or two or more. Two or more secondary batteries may be connected in series or in parallel.

　充電手段２０は、二次電池１０に電流を供給して、二次電池１０を充電する。充電手段２０としては、例えば、定電流充電装置、定電力充電装置を用いることができる。なお、本実施形態では、充電手段２０は、電池パック１００の内部に備えられているが、電池パック１００の外部、例えば、電池パック１００が装着される電気機器に備えられていてもよい。 The charging means 20 supplies a current to the secondary battery 10 to charge the secondary battery 10. As the charging means 20, for example, a constant current charging device or a constant power charging device can be used. In the present embodiment, the charging means 20 is provided inside the battery pack 100, but may be provided outside the battery pack 100, for example, in an electric device to which the battery pack 100 is mounted.

　制御システム３０は、二次電池１０の充電状態を制御する制御装置（コントローラー）である。制御システム３０は、例えば、マイコンである。制御システム３０は、検出手段３１、ｄＱ／ｄＶ算出手段３２、抽出手段３３、補正手段３４、記憶手段３５を有する。 The control system 30 is a control device (controller) that controls the state of charge of the secondary battery 10. The control system 30 is, for example, a microcomputer. The control system 30 includes a detection means 31, a dQ / dV calculation means 32, an extraction means 33, a correction means 34, and a storage means 35.

　検出手段３１は、二次電池１０に供給した電気量あるいは電力量、すなわち二次電池１０の充電量Ｑと二次電池１０の電圧Ｖとを検出する。充電量Ｑは、充電手段２０から二次電池１０に供給した電流値Ｉと電流の供給時間ｔとを乗じた値（Ｉ×ｔ）である。得られた充電量Ｑは、ＳＯＣ（充電率）に換算してもよい。ＳＯＣは、二次電池１０を満充電としたときの充電量に対して、充電中の二次電池１０に蓄電されている充電量の割合である。充電量Ｑと電圧Ｖの検出間隔は、充電手段２０から二次電池１０に供給する電流値などの条件によって変動するが、通常は１秒以上１０分以内である。 The detecting means 31 detects the amount of electricity or electric power supplied to the secondary battery 10, that is, the charge amount Q of the secondary battery 10 and the voltage V of the secondary battery 10. The charge amount Q is a value (I × t) obtained by multiplying the current value I supplied from the charging means 20 to the secondary battery 10 and the current supply time t. The obtained charge amount Q may be converted into SOC (charge rate). SOC is the ratio of the amount of charge stored in the secondary battery 10 being charged to the amount of charge when the secondary battery 10 is fully charged. The detection interval between the charge amount Q and the voltage V varies depending on conditions such as the current value supplied from the charging means 20 to the secondary battery 10, but is usually 1 second or more and 10 minutes or less.

　ｄＱ／ｄＶ算出手段３２は、検出手段３１によって検出された充電量Ｑを電圧Ｖで微分して、ｄＱ／ｄＶを算出する。ｄＱ／ｄＶは所定の検出間隔で検出された充電量Ｑの変化量ｄＱと電圧Ｖの変化量ｄＶとの比である。 The dQ / dV calculation means 32 calculates dQ / dV by differentiating the charge amount Q detected by the detection means 31 with the voltage V. dQ / dV is the ratio of the change amount dQ of the charge amount Q detected at a predetermined detection interval to the change amount dV of the voltage V.

　抽出手段３３は、二次電池１０の充電電圧と、二次電池１０の充電電圧の変化量に対する蓄電量の変化量の割合であるｄＱ／ｄＶとの関係を示すＶ－ｄＱ／ｄＶ曲線において、二次電池１０の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる上昇から下降に転じる最初の極値点若しくは該極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極大値若しくは該極大値と数学的に等価な点を第１点として抽出する。また、抽出手段３３は、二次電池１０の電圧Ｖが３．３５Ｖ以上３．３９Ｖ以下の範囲内に現れる下降から上昇に転じる最後の極値点若しくは該極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極小値若しくは該極小値と数学的に等価な点を第２点として抽出する。更に、抽出手段３３は、二次電池１０の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる上昇から下降に転じる最初の極値点若しくは該極値点と数学的に等価な点、又は低電圧側から数えて３番目に現れる極大値若しくは該極大値と数学的に等価な点を第３点として抽出する。 The extraction means 33 is a V−dQ / dV curve showing the relationship between the charging voltage of the secondary battery 10 and dQ / dV, which is the ratio of the amount of change in the amount of electricity stored to the amount of change in the charging voltage of the secondary battery 10. The voltage V of the secondary battery 10 appears in the range of 3.34 V or more and less than 3.38 V. The second maximum value or a point mathematically equivalent to the maximum value is extracted as the first point. Further, the extraction means 33 is the last extreme point at which the voltage V of the secondary battery 10 appears in the range of 3.35 V or more and 3.39 V or less and changes from falling to rising, or a point mathematically equivalent to the extreme point. Or, the minimum value that appears second from the low voltage side or a point that is mathematically equivalent to the minimum value is extracted as the second point. Further, the extraction means 33 is the first extremum point at which the voltage V of the secondary battery 10 appears within the range of 3.38 V or more and 3.42 V or less and changes from ascending to descending, or a point mathematically equivalent to the extremum point. Or, the maximum value that appears third from the low voltage side or a point that is mathematically equivalent to the maximum value is extracted as the third point.

　補正手段３４は、上記第１点における充電量Ｑ_１ｓｔと第２点における充電量Ｑ_２ｎｄとの差であるΔＱを算出すると共に、二次電池１０のＳＯＣを、下記の式（１）で求められるＮへ補正する。
Ｎ＝ＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝　　　・・・（１）
　但し、式（１）において、ｄＱ／ｄＶ_３ｒｄは、第３点における二次電池１０の電圧の変化量に対する充電量の変化量の割合を表し、Ｑ_ｆは、前記二次電池の初期状態の満充電容量を表し、Ａは、０．１≦Ａ≦１０を満足する数を表す。 The correction means 34 _{calculates ΔQ, which is the difference between the charge amount Q 1st} at the first point and the charge amount Q _{2nd at} the second point, and obtains the SOC of the secondary battery 10 by the following equation (1). Correct to N.
N = SOC {(dQ / dV _3rd ) / Q _f −ΔQ * A} ・ ・ ・ (1)
However, in the formula (1), dQ / dV _3rd represents the ratio of the change amount of the charge amount to the change amount of the voltage of the secondary battery 10 at the third point, and Q _f is the initial state of the secondary battery. It represents a full charge capacity, and A represents a number satisfying 0.1 ≦ A ≦ 10.

　式（１）の｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝の部分（以下、補正時期算出項ともいう）は、ＳＯＣの補正時期、すなわち充電中の二次電池１０のＳＯＣを補正するタイミングを指標する。補正時期算出項により算出される補正時点は、第３点のｄＱ／ｄＶ_３ｒｄから、［（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ］に相当するｄＱ／ｄＶが減少した時点である。第３点の位置は、二次電池１０の充放電を繰り返すことによって変動しやすい。これに対して、第３点から、［（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ］に相当するｄＱ／ｄＶが減少した時点は、第３点の位置と比較すると変動しにくい。このため、上記の補正時期算出項により算出される補正時点に基づいてＳＯＣを補正することによって、充電中の二次電池１０のＳＯＣを高い精度で推定することができる。ＳＯＣの補正を行なうタイミングは、補正時期算出項で算出された時点であってもよいし、補正時期算出項で算出された時点からある程度の期間を経過した時点であってもよい。また、ＳＯＣの補正は、補正時期算出項で算出された時点から間隔をあけて複数回行なってもよい。補正時期は、例えば、Ｑ－Ｖ曲線からＱとｄＱ／ｄＶの関係を示すＱ－ｄＱ／ｄＶ曲線を作成して、第１点における充電量Ｑ_１ｓｔと、第２点における充電量Ｑ_２ｎｄと、第３点におけるｄＱ／ｄＶ_３ｒｄとを得ることによって計算してもよい。また、Ｑ－ｄＱ／ｄＶ曲線の代わりにＳＯＣ－ｄＱ／ｄＶ曲線を用いてもよい。この場合にも、第１点における充電量Ｑ_１ｓｔと、第２点における充電量Ｑ_２ｎｄと、第３点におけるｄＱ／ｄＶ_３ｒｄとを得ることによって計算することができる。 The {(dQ / dV _3rd ) / Q _f −ΔQ * A} part of the formula (1) (hereinafter, also referred to as a correction time calculation term) indicates the SOC correction time, that is, the SOC of the secondary battery 10 being charged. Index the timing of correction. The correction time point calculated by the correction time calculation term is the time when dQ / dV corresponding to [(dQ / dV _3rd ) / Q _f −ΔQ * A] decreases _{from the third point dQ / dV 3rd.} The position of the third point is likely to fluctuate by repeating charging and discharging of the secondary battery 10. On the other hand, _{when dQ / dV corresponding to [(dQ / dV 3rd} ) / Q _f −ΔQ * A] decreases from the third point, it is less likely to fluctuate as compared with the position of the third point. Therefore, by correcting the SOC based on the correction time point calculated by the above-mentioned correction timing calculation term, the SOC of the secondary battery 10 being charged can be estimated with high accuracy. The timing for correcting the SOC may be a time point calculated by the correction time calculation term, or a time point after a certain period of time has elapsed from the time point calculated by the correction time calculation term. Further, the SOC may be corrected a plurality of times at intervals from the time point calculated by the correction time calculation term. For the correction timing, for example, a Q-dQ / dV curve showing the relationship between Q and dQ / dV is created from the QV curve, and the charge amount Q _1st at the first point and the charge amount Q _{2nd at the second point are used.} , It may be calculated by obtaining dQ / dV _{3rd at the third point.} Further, the SOC-dQ / dV curve may be used instead of the Q-dQ / dV curve. Also in this case, it can be calculated by obtaining the _{charge amount Q 1st} at the first point, the charge amount Q _2nd at the second point, and dQ / dV _{3rd at the third point.}

　式（１）のＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ／Ｑ_ｆ）－ΔＱ＊Ａ｝は、補正時期算出項で算出された補正時点でのＳＯＣ（以下、補正ＳＯＣ値ともいう）を意味する。補正ＳＯＣ値は、例えば、ＳＯＣ－ｄＱ／ｄＶ曲線から第１点における充電量Ｑ_２ｎｄと、第２点における充電量Ｑ_２ｎｄと、第３点におけるｄＱ／ｄＶ_３ｒｄを得、更に初期状態の満充電容量Ｑ_ｆを得て、Ａを０．１≦Ａ≦１０を満足する数として、上記式（１）の補正時期算出項により補正時期を算出し、次いで、ＳＯＣ－ｄＱ／ｄＶ曲線の補正時期に対応するＳＯＣ値を読み取ることによって得ることができる。このＳＯＣ値を補正ＳＯＣ値として記憶手段３５に予め記憶させる。補正ＳＯＣ値は、二次電池１０の初期状態、又は基準二次電池から算出することができる。
　補正ＳＯＣ値は、基準二次電池を用い、満放電状態から充電した際の基準二次電池のＳＯＣと、基準二次電池の充電量Ｑを基準二次電池の電圧Ｖで微分して得たｄＱ／ｄＶとの関係を示すＳＯＣ－ｄＱ／ｄＶ曲線を用いて算出してもよい。この場合、補正ＳＯＣ値は、例えば、基準二次電池のＳＯＣ－ｄＱ／ｄＶ曲線から第１点における充電量Ｑ_１ｓｔと、第２点における充電量Ｑ_２ｎｄと、第３点におけるｄＱ／ｄＶ_３ｒｄを得て、Ａを０．１≦Ａ≦１０を満足する数として、上記式（１）の補正時期算出項により補正時期を算出し、次いで、ＳＯＣ－ｄＱ／ｄＶ曲線の補正時期に対応するＳＯＣ値を読み取ることによって得ることができる。基準二次電池は、電池を構成する各材料が二次電池１０と同一で、電池を充電したときのＳＯＣ－ｄＱ／ｄＶ曲線が二次電池１０と同一の電池であるのが好ましい。基準二次電池は、電池パック１００に組み込まれた二次電池１０の初期状態であってもよいし、充電中の二次電池１０とは別の電池であってもよい。なお、二次電池１０の初期状態とは、充放電サイクルの回数が１０回以下の状態である。 The SOC {(dQ / dV _3rd / Q _f ) -ΔQ * A} in the formula (1) means the SOC (hereinafter, also referred to as the corrected SOC value) at the time of correction calculated by the correction time calculation term. Correction SOC value is, for example, a charge amount _{Q 2nd} in the first point from the SOC-dQ / dV curve, the charge amount _{Q 2nd} in the second point, to obtain a dQ _{/ dV 3rd} in the third point, Mitsuru further initial state The charge capacity Q _f is obtained, A is set to a number satisfying 0.1 ≦ A ≦ 10, the correction time is calculated by the correction time calculation term of the above formula (1), and then the SOC−dQ / dV curve is corrected. It can be obtained by reading the SOC value corresponding to the time. This SOC value is stored in the storage means 35 in advance as a corrected SOC value. The corrected SOC value can be calculated from the initial state of the secondary battery 10 or the reference secondary battery.
The corrected SOC value was obtained by differentiating the SOC of the reference secondary battery when charged from a fully discharged state and the charge amount Q of the reference secondary battery by the voltage V of the reference secondary battery using the reference secondary battery. It may be calculated using the SOC-dQ / dV curve showing the relationship with dQ / dV. In this case, the corrected SOC values are, for example, the charge amount Q _1st at the first point, the charge amount Q _2nd at the second point, and the dQ / dV _{3rd at the third point from the SOC-dQ / dV curve of the reference secondary battery.} Then, with A as a number satisfying 0.1 ≦ A ≦ 10, the correction time is calculated by the correction time calculation term of the above equation (1), and then the correction time of the SOC−dQ / dV curve corresponds to the correction time. It can be obtained by reading the SOC value. It is preferable that the reference secondary battery is a battery in which each material constituting the battery is the same as that of the secondary battery 10 and the SOC−dQ / dV curve when the battery is charged is the same as that of the secondary battery 10. The reference secondary battery may be in the initial state of the secondary battery 10 incorporated in the battery pack 100, or may be a battery different from the secondary battery 10 being charged. The initial state of the secondary battery 10 is a state in which the number of charge / discharge cycles is 10 or less.

　記憶手段３５は、上記の補正時期算出項や、上記で得られたＳＯＣ－ｄＱ／ｄＶ曲線、基準二次電池のＳＯＣ－ｄＱ／ｄＶ曲線、二次電池１０の初期状態又は基準二次電池から算出された補正ＳＯＣ値等が記憶されている。 The storage means 35 is based on the above correction timing calculation term, the SOC-dQ / dV curve obtained above, the SOC-dQ / dV curve of the reference secondary battery, the initial state of the secondary battery 10, or the reference secondary battery. The calculated corrected SOC value and the like are stored.

　次に、本実施形態の電池パック１００を用いた二次電池１０の制御方法を説明する。
　始めに、二次電池１０を、充電手段２０を用いて充電しながら、検出手段３１にて二次電池１０の充電量Ｑ（二次電池１０に供給した電気量あるいは電力量）と二次電池１０の電圧Ｖとを検出する。二次電池１０の充電は、定電流充電で行なうことが好ましい。充電時の電流値は、二次電池１０を満放電状態から１時間で満充電状態となるように充電するときの電流量を１Ｃとして、０．１Ｃ以上２Ｃ以下の範囲内にあることが好ましい。 Next, a method of controlling the secondary battery 10 using the battery pack 100 of the present embodiment will be described.
First, while charging the secondary battery 10 using the charging means 20, the charging amount Q (the amount of electricity or electric power supplied to the secondary battery 10) of the secondary battery 10 and the secondary battery by the detecting means 31 A voltage V of 10 is detected. The secondary battery 10 is preferably charged by constant current charging. The current value at the time of charging is preferably in the range of 0.1C or more and 2C or less, where 1C is the amount of current when the secondary battery 10 is charged from the fully discharged state to the fully charged state in 1 hour. ..

　図２は、本発明の一実施形態にかかる電池パックを用いて二次電池を充電したときの充電量Ｑと電圧Ｖの関係を示すＱ－Ｖ曲線を示すグラフである。図２において、横軸は二次電池１０の充電量Ｑであり、縦軸は二次電池１０の電圧Ｖである。以下の図２～図６において、符号１０ｎは充放電サイクルを５００回行った二次電池１０のデータを表し、符号１０ｉは初期状態（充放電サイクルの回数が１０回以下）の二次電池１０のデータを表す。なお、充放電サイクルは、２５℃において、０．１Ｃに相当する定電流で終止電圧３．６Ｖまで充電（満充電）し、その後０．１Ｃに相当する定電流で２．６Ｖまで放電（満放電）する条件で行なった。 FIG. 2 is a graph showing a QV curve showing the relationship between the charge amount Q and the voltage V when the secondary battery is charged using the battery pack according to the embodiment of the present invention. In FIG. 2, the horizontal axis is the charge amount Q of the secondary battery 10, and the vertical axis is the voltage V of the secondary battery 10. In FIGS. 2 to 6 below, reference numeral 10n represents data of the secondary battery 10 that has undergone 500 charge / discharge cycles, and reference numeral 10i is the secondary battery 10 in the initial state (the number of charge / discharge cycles is 10 or less). Represents the data of. In the charge / discharge cycle, the battery is charged (fully charged) to a final voltage of 3.6 V with a constant current corresponding to 0.1 C at 25 ° C., and then discharged (fully charged) to 2.6 V with a constant current corresponding to 0.1 C. It was carried out under the condition of discharging).

　次に、充電量Ｑを二次電池の電圧Ｖで微分してｄＱ／ｄＶを算出する。図３は、図２のＱ－Ｖ曲線から算出したＶ－ｄＱ／ｄＶ曲線を示すグラフである。図４は、図３のグラフの極値点（Ｐ１）及び極値点（Ｂ１）付近を拡大して示すグラフである。図５は、図３のグラフの極値点（Ｐ２）、極値点（Ｂ２）及び極値点（Ｐ３）付近を拡大して示すグラフである。図３～図５において、横軸は二次電池１０の電圧Ｖであり、縦軸はｄＱ／ｄＶ値である。 Next, the charge amount Q is differentiated by the voltage V of the secondary battery to calculate dQ / dV. FIG. 3 is a graph showing a VdQ / dV curve calculated from the QV curve of FIG. FIG. 4 is an enlarged graph showing the vicinity of the extremum point (P1) and the extremum point (B1) in the graph of FIG. FIG. 5 is an enlarged graph showing the vicinity of the extremum point (P2), the extremum point (B2), and the extremum point (P3) in the graph of FIG. In FIGS. 3 to 5, the horizontal axis represents the voltage V of the secondary battery 10 and the vertical axis represents the dQ / dV value.

　図３～図５に示すように、Ｖ－ｄＱ／ｄＶ曲線は３つの極値点（Ｐ１_ｉ～Ｐ３_ｉとＰ１_ｎ～Ｐ３_ｎ）と、２つの極値点（Ｂ１_ｉ～Ｂ２_ｉとＢ１_ｎ～Ｂ２_ｎ）とを有する。極値点（Ｐ）は、ｄＱ／ｄＶ値が上昇から下降に転じる点であり、極値点（Ｂ）は、ｄＱ／ｄＶ値が下降から上昇に転じる点である。極値点（Ｐ１_ｉ、Ｐ１_ｎ）は、二次電池の電圧が３．２２Ｖ以上３．３４Ｖ未満の範囲内に現れる、ｄＱ／ｄＶ値が上昇から下降に転じる最初の極値点であり、二次電池１０を満放電状態から充電した際の充電量Ｑと電圧Ｖの関係を示すＱ－Ｖ曲線を微分した場合に低電圧側から数えて１番目に現れる極大点（ピークトップ）である。極値点（Ｂ１_ｉ、Ｂ１_ｎ）は、二次電池の電圧が３．２２Ｖ以上３．３４Ｖ未満の範囲内に現れる、ｄＱ／ｄＶ値が下降から上昇に転じる最後の極値点であり、二次電池１０を満放電状態から充電した際の充電量Ｑと電圧Ｖの関係を示すＱ－Ｖ曲線を微分した場合に低電圧側から数えて１番目に現れる極値点（ピークボトム）である。極値点（Ｐ２_ｉ、Ｐ２_ｎ）は、二次電池の電圧が３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる、ｄＱ／ｄＶ値が上昇から下降に転じる最初の極値点であり、二次電池１０を満放電状態から充電した際のＱ－Ｖ曲線を微分した場合に低電圧側から数えて２番目に現れる極大点（ピークトップ）である。極値点（Ｂ２_ｉ、Ｂ２_ｎ）は、二次電池の電圧が３．３５Ｖ以上３．３９Ｖ未満の範囲内に現れる、ｄＱ／ｄＶ値が下降から上昇に転じる最後の極値点であり、二次電池１０を満放電状態から充電した際のＱ－Ｖ曲線を微分した場合に低電圧側から数えて２番目に現れる極小点（ピークボトム）である。極値点（Ｐ３_ｉ、Ｐ３_ｎ）は、二次電池の電圧が３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる、ｄＱ／ｄＶ値が上昇から下降に転じる最初の極値点であり、二次電池１０を満放電状態から充電した際のＱ－Ｖ曲線を微分した場合に低電圧側から数えて３番目に現れる極大点（ピークトップ）である。
　極値点は、二次電池１０の充電反応に寄与する正極活物質もしくは負極活物質のステージが切り替わることを示す。したがって、ピークの形状及び位置は、二次電池１０の正極活物質及び負極活物質の材料によって異なる。 As shown in FIGS. 3 to 5, the VdQ / dV curve has three extremum points (P1 _i to P3 _i and P1 _n to P3 _n ) and two extremum points (B1 _i to B2 _i and B1). _n to B2 _n ). The extremum point (P) is the point where the dQ / dV value changes from rising to falling, and the extremum point (B) is the point where the dQ / dV value changes from falling to rising. The extreme point (P1 _i , P1 _n ) is the first extreme point at which the voltage of the secondary battery appears in the range of 3.22 V or more and less than 3.34 V, and the dQ / dV value changes from rising to falling. This is the maximum point (peak top) that appears first when counting from the low voltage side when the QV curve showing the relationship between the charge amount Q and the voltage V when the secondary battery 10 is charged from the fully discharged state is differentiated. .. The extreme point (B1 _i , B1 _n ) is the last extreme point at which the voltage of the secondary battery appears in the range of 3.22 V or more and less than 3.34 V, and the dQ / dV value changes from falling to rising. At the extreme value point (peak bottom) that appears first when counting from the low voltage side when the QV curve showing the relationship between the charge amount Q and the voltage V when the secondary battery 10 is charged from the fully discharged state is differentiated. be. The extreme point (P2 _i , P2 _n ) is the first extreme point at which the voltage of the secondary battery appears in the range of 3.34 V or more and less than 3.38 V, and the dQ / dV value changes from rising to falling. This is the maximum point (peak top) that appears second from the low voltage side when the QV curve when the secondary battery 10 is charged from the fully discharged state is differentiated. The extreme point (B2 _i , B2 _n ) is the last extreme point at which the voltage of the secondary battery appears in the range of 3.35 V or more and less than 3.39 V, and the dQ / dV value changes from falling to rising. This is the minimum point (peak bottom) that appears second from the low voltage side when the QV curve when the secondary battery 10 is charged from the fully discharged state is differentiated. The extreme point (P3 _i , P3 _n ) is the first extreme point at which the voltage of the secondary battery appears in the range of 3.38 V or more and 3.42 V or less, and the dQ / dV value changes from rising to falling. This is the maximum point (peak top) that appears third from the low voltage side when the QV curve when the secondary battery 10 is charged from the fully discharged state is differentiated.
The extreme value point indicates that the stage of the positive electrode active material or the negative electrode active material that contributes to the charging reaction of the secondary battery 10 is switched. Therefore, the shape and position of the peak differ depending on the material of the positive electrode active material and the negative electrode active material of the secondary battery 10.

　次に、二次電池１０の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる、上昇から下降に転じる最初の極値点（Ｐ２_ｉ、Ｐ２_ｎ）を第１点として抽出する。第１点は、Ｑ－Ｖ曲線上で上記極値点と数学的に等価な点であってもよい。また、第１点は、Ｖ－ｄＱ／ｄＶ曲線において、低電圧側から数えて２番目に現れる極大値若しくは該極大値と数学的に等価な点であってもよい。
　また、同様にして、二次電池の電圧が３．３５Ｖ以上３．３９Ｖ未満の範囲内に現れる、ｄＱ／ｄＶ値が下降から上昇に転じる最後の極値点（Ｂ２_ｉ、Ｂ２_ｎ）を第２点として抽出する。第２点は、Ｑ－Ｖ曲線上で上記極値点と数学的に等価な点であってもよい。また、第２点は、Ｖ－ｄＱ／ｄＶ曲線において、低電圧側から数えて２番目に現れる極小値若しくは該極小値と数学的に等価な点であってもよい。
　更に、同様にして、二次電池１０の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる、上昇から下降に転じる最初の極値点（Ｐ３_ｉ、Ｐ３_ｎ）を第３点として抽出する。第３点は、Ｑ－Ｖ曲線上で上記極値点と数学的に等価な点であってもよい。また、第３点は、Ｖ－ｄＱ／ｄＶ曲線において、低電圧側から数えて３番目に現れる極大値若しくは該極大値と数学的に等価な点であってもよい。 _{Next, the first extreme point (P2 i} , P2 _n ) at which the voltage V of the secondary battery 10 changes from rising to falling, which appears in the range of 3.34 V or more and less than 3.38 V, is extracted as the first point. The first point may be a point mathematically equivalent to the extremum point on the QV curve. Further, the first point may be a maximum value that appears second from the low voltage side in the V-dQ / dV curve or a point that is mathematically equivalent to the maximum value.
_{Similarly, the last extreme point (B2 i} , B2 _n ) at which the voltage of the secondary battery appears in the range of 3.35 V or more and less than 3.39 V and the dQ / dV value changes from falling to rising is set. Extract as 2 points. The second point may be a point mathematically equivalent to the extremum point on the QV curve. Further, the second point may be a minimum value that appears second from the low voltage side in the V−dQ / dV curve or a point that is mathematically equivalent to the minimum value.
_{Further, similarly, the first extreme point (P3 i} , P3 _n ) at which the voltage V of the secondary battery 10 appears in the range of 3.38 V or more and 3.42 V or less and changes from rising to falling is set as the third point. Extract. The third point may be a point mathematically equivalent to the extremum point on the QV curve. Further, the third point may be a maximum value appearing third from the low voltage side in the V-dQ / dV curve or a point mathematically equivalent to the maximum value.

　次に、二次電池１０のＳＯＣを、上記の式（１）で求められるＮへ補正する。例えば、ＳＯＣ補正時期に、記憶手段３５に記憶されている補正ＳＯＣ値へ補正する。 Next, the SOC of the secondary battery 10 is corrected to N obtained by the above formula (1). For example, at the SOC correction period, the corrected SOC value stored in the storage means 35 is corrected.

　　図６は、図２のＱ－Ｖ曲線から算出したＳＯＣ－ｄＱ／ｄＶ曲線を示すグラフである。図７（ａ）は、図６のグラフの極値点（Ｐ３）付近を拡大して示すグラフであり、図７（ｂ）は、ＳＯＣ補正の際に用いられるΔＱを示すグラフである。図６及び図７において、横軸は二次電池１０のＳＯＣ値であり、縦軸はｄＱ／ｄＶ値である。 FIG. 6 is a graph showing the SOC-dQ / dV curve calculated from the QV curve of FIG. FIG. 7A is an enlarged graph showing the vicinity of the extreme value point (P3) in the graph of FIG. 6, and FIG. 7B is a graph showing ΔQ used at the time of SOC correction. In FIGS. 6 and 7, the horizontal axis is the SOC value of the secondary battery 10, and the vertical axis is the dQ / dV value.

　Ｎの算出方法を、初期状態の二次電池１０のデータ１０_ｉを用いて説明する。
　先ず、初期状態のＳＯＣ補正時期を、次のようにして算出する。極値点（Ｐ２_ｉ）（第１点）における充電量Ｑ_Ｐ２ｉ（＝Ｑ_１ｓｔ）と、極値点（Ｂ２_ｉ）（第２点）における充電量Ｑ_Ｂ２ｉと、極値点（Ｐ３_ｉ）におけるｄＱ／ｄＶ_Ｐ３ｉ（＝ｄＱ／ｄＶ_３ｒｄ）とを読み取る。次いで、充電量Ｑ_Ｐ２ｉと充電量Ｑ_Ｂ２ｉの差であるΔＱを算出し、得られたｄＱ／ｄＶ_Ｐ３ｉ及びΔＱと、二次電池１０の初期状態の満充電容量Ｑ_ｆと、０．１以上１０以下の範囲内の任意定数として設定された定数Ａとを、上記式（１）の補正時期算出項に代入する。ＳＯＣ補正時期は、極値点（Ｐ３_ｉ）からｄＱ／ｄＶがｄＱ／ｄＶ_Ｐ３ｉ－ΔＱ＊Ａとなるまで充電した点（図７（ａ）においてＰ３_ｉ’）である。 The method of calculating N will be described using _{the data 10 i} of the secondary battery 10 in the initial state.
First, the SOC correction time in the initial state is calculated as follows. _{Charge amount Q P2i} (= Q _1st ) at extreme point (P2 _i ) (first point), _{charge amount Q B2i at} extreme point (B2 _i ) (second point), and extreme point (P3 _i ) In dQ / dV _P3i (= dQ / dV _3rd ). Next, ΔQ, which is the difference between the charge amount Q _P2i and the charge amount Q _B2i , is calculated, and the obtained dQ / dV _{P3i and ΔQ, the full charge capacity Q f in} the initial state of the secondary battery 10, and 0.1 or more. The constant A set as an arbitrary constant within the range of 10 or less is substituted into the correction timing calculation term of the above equation (1). The SOC correction period is a point _{charged from the extreme value point (P3 i} ) until dQ / dV becomes dQ / dV _{P3i −ΔQ * A (P3 i} ′ in FIG. 7 (a)).

　次に、ＳＯＣ補正時期（Ｐ３_ｉ’）におけるＳＯＣ_Ｐ３ｉ’の値を読み取る。図７においては、ＳＯＣ_Ｐ３ｉ’の値は７０％である。このＳＯＣ_Ｐ３ｉ’の値（７０％）を補正ＳＯＣ値として記憶手段３５へ記憶させる。この補正ＳＯＣ値の算出は初期状態の二次電池１０から求めてもよいし、様々な劣化条件で劣化させた基準サンプルから算出してもよい。 Next, read the value of the _{'SOC P3i} in SOC correction timing (P3 _i)'. In FIG. 7, the value of _{SOC P3i'is 70%.} The value (70%) of this SOC _P3i'is stored in the storage means 35 as a corrected SOC value. The calculation of the corrected SOC value may be obtained from the secondary battery 10 in the initial state, or may be calculated from the reference sample deteriorated under various deterioration conditions.

　充電中の二次電池１０のＳＯＣ補正時期を、次のようにして算出する。極値点（Ｐ２_ｎ）（第１点）における充電量Ｑ_Ｐ２ｎ（＝Ｑ_１ｓｔ）と、極値点（Ｂ２_ｎ）（第２点）における充電量Ｑ_Ｂ２ｎ（＝Ｑ_２ｎｄ）と、極値点（Ｐ３_ｎ）（第２点）におけるｄＱ／ｄＶ_Ｐ３ｎ（＝ｄＱ／ｄＶ_３ｒｄ）とを読み取る。次いで、充電量Ｑ_Ｐ２ｎと充電量Ｑ_Ｂ２ｎの差であるΔＱを算出し、得られたｄＱ／ｄＶ_Ｐ３ｎ及びΔＱと、初期状態の満充電容量Ｑ_ｆと、０．１以上１０以下の範囲内の任意定数として設定されたＡとを、上記式（１）の補正時期算出項に代入する。ＳＯＣ補正時期は、極値点（Ｐ３_ｎ）からｄＱ／ｄＶが（ｄＱ／ｄＶ_Ｐ３ｎ）／Ｑ_ｆ－ΔＱ＊Ａ下がるまでに充電した点（図７（ａ）においてＰ３_ｎ’）である。
　そして、ＳＯＣ補正時期（Ｐ３_ｎ’）となるまで充電し、ＳＯＣ補正時期に到達した時点で補正ＳＯＣ値に補正する。 The SOC correction timing of the secondary battery 10 being charged is calculated as follows. _{Charge amount Q P2n} (= Q _1st ) at extreme point (P2 _n ) (first point), _{charge amount Q B2n} (= Q _2nd ) at extreme point (B2 _n ) (second point), and extreme value _{The dQ / dV P3n} (= dQ / dV _3rd ) at the point (P3 _n ) (second point) is read. Then, the charge amount _{Q P2n} and calculates ΔQ is the difference between the charge amount _{Q B2n,} and dQ _{/ dV P3n} and ΔQ obtained, and full initial state charge capacity _{Q f,} in the range of 0.1 to 10 A, which is set as an arbitrary constant of, is substituted into the correction time calculation term of the above equation (1). The SOC correction period is the point at which charging is performed from the extreme value point (P3 _n ) until dQ / dV _{drops (dQ / dV P3n} ) / Q _{f − ΔQ * A (P3 n} ′ in FIG. 7 (a)).
Then, the battery is charged until the SOC correction time (P3 _n ') is reached, and when the SOC correction time is reached, the correction SOC value is corrected.

　次に、本実施形態において用いる二次電池１０について説明する。図８は、本発明の一実施形態にかかる電池パックにおいて用いることができる二次電池の断面図である。二次電池１０は、リチウムイオン二次電池であり、例えば、発電素子４と外装体５と電解液（図示略）とを備える。外装体５は、発電素子４の周囲を被覆する。外装体５は、例えば、金属箔５Ａを高分子膜（樹脂層５Ｂ）で両側からコーティングした金属ラミネートフィルムである。発電素子４は、接続された一対の端子６によって外部と接続される。電解液は、外装体５内に収容され、発電素子４内に含浸している。 Next, the secondary battery 10 used in the present embodiment will be described. FIG. 8 is a cross-sectional view of a secondary battery that can be used in the battery pack according to the embodiment of the present invention. The secondary battery 10 is a lithium ion secondary battery, and includes, for example, a power generation element 4, an exterior body 5, and an electrolytic solution (not shown). The exterior body 5 covers the periphery of the power generation element 4. The exterior body 5 is, for example, a metal laminate film in which a metal foil 5A is coated from both sides with a polymer film (resin layer 5B). The power generation element 4 is connected to the outside by a pair of connected terminals 6. The electrolytic solution is housed in the exterior body 5 and impregnated in the power generation element 4.

　発電素子４は、正極２と負極３とセパレータ１とを備える。セパレータ１は、正極２と負極３とに挟まれる。セパレータ１は、例えば、電気絶縁性の多孔質構造を有するフィルムである。セパレータ１としては、リチウムイオン二次電池において一般に使用されている公知のものを用いることができる。 The power generation element 4 includes a positive electrode 2, a negative electrode 3, and a separator 1. The separator 1 is sandwiched between the positive electrode 2 and the negative electrode 3. The separator 1 is, for example, a film having an electrically insulating porous structure. As the separator 1, a known separator generally used in a lithium ion secondary battery can be used.

　正極２は、正極集電体２Ａと正極活物質層２Ｂとを有する。正極活物質層２Ｂは、正極集電体２Ａの少なくとも一面に形成されている。正極活物質層２Ｂは、正極集電体２Ａの両面に形成されていてもよい。正極集電体２Ａは、例えば、導電性の板材である。正極活物質層２Ｂは、例えば、正極活物質と導電助材とバインダーとを有する。 The positive electrode 2 has a positive electrode current collector 2A and a positive electrode active material layer 2B. The positive electrode active material layer 2B is formed on at least one surface of the positive electrode current collector 2A. The positive electrode active material layer 2B may be formed on both surfaces of the positive electrode current collector 2A. The positive electrode current collector 2A is, for example, a conductive plate material. The positive electrode active material layer 2B has, for example, a positive electrode active material, a conductive auxiliary material, and a binder.

　正極活物質は、一般式ＬｉＦｅ_１－ＸＭ_ＸＰＯ_４で表されるリン酸鉄リチウム化合物を含む。但し、上記の一般式において、Ｍは、Ｍｎ，Ｃｒ，Ｃｏ，Ｃｕ，Ｎｉ，Ｖ，Ｍｏ，Ｔｉ，Ｚｎ，Ａｌ，Ｇａ，Ｍｇ，Ｂ，Ｎｂからなる群より選ばれる少なくとも一つの元素を表し、ｘは、０≦Ｘ≦０．５を満たす数を表す。正極活物質は、リン酸鉄リチウム化合物を８０質量％以上含むことが好ましく、９０質量％以上含むことがより好ましい。 The positive electrode active material, includes a general formula _{LiFe 1-X} M _X PO lithium iron phosphate compound represented by _4. However, in the above general formula, M represents at least one element selected from the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B and Nb. , X represent a number satisfying 0 ≦ X ≦ 0.5. The positive electrode active material preferably contains a lithium iron phosphate compound in an amount of 80% by mass or more, and more preferably 90% by mass or more.

　負極３は、負極集電体３Ａと負極活物質層３Ｂとを有する。負極活物質層３Ｂは、負極集電体３Ａの少なくとも一面に形成されている。負極活物質層３Ｂは、負極集電体３Ａの両面に形成されていてもよい。負極集電体３Ａは、例えば、導電性の板材である。負極活物質層３Ｂは、例えば、負極活物質と導電助材とバインダーとを有する。 The negative electrode 3 has a negative electrode current collector 3A and a negative electrode active material layer 3B. The negative electrode active material layer 3B is formed on at least one surface of the negative electrode current collector 3A. The negative electrode active material layer 3B may be formed on both surfaces of the negative electrode current collector 3A. The negative electrode current collector 3A is, for example, a conductive plate material. The negative electrode active material layer 3B has, for example, a negative electrode active material, a conductive auxiliary material, and a binder.

　正極活物質は、黒鉛を含む。黒鉛としては、人造黒鉛、天然黒鉛を用いることができる。負極活物質は、黒鉛を８０質量％以上含むことが好ましく、９０質量％以上含むことがより好ましい。 The positive electrode active material contains graphite. As the graphite, artificial graphite or natural graphite can be used. The negative electrode active material preferably contains 80% by mass or more of graphite, and more preferably 90% by mass or more.

　電解液は、外装体５内に封入され、発電素子４に含浸している。電解液としては、リチウムイオン二次電池において一般に使用されている公知のものを用いることができる。 The electrolytic solution is sealed in the exterior body 5 and impregnated in the power generation element 4. As the electrolytic solution, a known one generally used in a lithium ion secondary battery can be used.

　上記の構成のリチウムイオン二次電池においては、図３～図５に示すＶ－ｄＱ／ｄＶ曲線における極値点（Ｐ１_ｉ、Ｐ１_ｎ）及び極値点（Ｂ１_ｉ、Ｂ１_ｎ）が黒鉛のステージ４に由来するピークであり、極値点（Ｐ２_ｉ、Ｐ２_ｎ）及び極値点（Ｂ２_ｉ、Ｂ２_ｎ）が黒鉛のステージ２に由来するピークであり、極値点（Ｐ３_ｉ、Ｐ３_ｎ）が黒鉛のステージ１に由来するピークである。リチウムイオン二次電池の充放電を繰り返すことによって、黒鉛が劣化すると、図６及び図７に示すＳＯＣ－ｄＱ／ｄＶ曲線では、極値点（Ｐ２）及び極値点（Ｐ３）が、高ＳＯＣ側にシフトし、極値点（Ｂ２）が低ＳＯＣ側にシフトする。このため、黒鉛が劣化すると、極値点（Ｐ２）、極値点（Ｂ２）及び極値点（Ｐ３）ではＳＯＣ値を精度よく推定することが難しい。 In the lithium ion secondary battery having the above configuration, the extreme points (P1 _i , P1 _n ) and the extreme points (B1 _i , B1 _n ) in the VdQ / dV curves shown in FIGS. 3 to 5 are made of graphite. The peaks are derived from stage 4, and the extremum points (P2 _i , P2 _n ) and the extremum points (B2 _i , B2 _n ) are the peaks derived from stage 2 of graphite, and the extremum points (P3 _i , P3). _n ) is the peak derived from stage 1 of graphite. When graphite deteriorates due to repeated charging and discharging of the lithium ion secondary battery, the extremum points (P2) and extremum points (P3) have high SOCs in the SOC-dQ / dV curves shown in FIGS. 6 and 7. It shifts to the side, and the extremum point (B2) shifts to the low SOC side. Therefore, when graphite deteriorates, it is difficult to accurately estimate the SOC value at the extremum point (P2), the extremum point (B2), and the extremum point (P3).

　本実施形態にかかる電池パック１００では、例えば充電手段２０により二次電池１０を充電しながら、制御システム３０において、第１点（極値点（Ｐ２））、第２点（極値点（Ｂ２））及び第３点（極値点（Ｐ３））を抽出し、第１点における充電量Ｑ_１ｓｔと、第２点における充電量Ｑ_２ｎｄと、第３点におけるｄＱ／ｄＶ_３ｒｄと、二次電池１０の初期状態の満充電容量Ｑ_ｆとに基づいて算出した［（ｄＱ／ｄＶ_３ｒｄｄ）／Ｑ_ｆ－ΔＱ＊Ａ］に相当するｄＱ／ｄＶの位置、又はその位置以降でＳＯＣを補正する。この補正時点の位置は第３点の位置と比較すると変動しにくい。このため、制御システム３０によれば、充電中の二次電池１０のＳＯＣを高い精度で推定することができる。 In the battery pack 100 according to the present embodiment, for example, while charging the secondary battery 10 by the charging means 20, the control system 30 has a first point (extreme point (P2)) and a second point (extreme point (B2)). )) And the third point (extreme point (P3)) are extracted, and the charge amount Q _1st at the first point, the charge amount Q _2nd at the second point, dQ / dV _{3rd at} the third point, and the secondary. It was calculated based on the full charge capacity _{Q f} of the initial state of the battery 10 position of _{[(dQ / dV 3rdd) /} Q f -ΔQ * a] corresponding to dQ / dV, or corrects the SOC at that position later .. The position at the time of this correction is less likely to fluctuate as compared with the position of the third point. Therefore, according to the control system 30, the SOC of the secondary battery 10 being charged can be estimated with high accuracy.

　また、本実施形態にかかる電池パック１００においては、制御システム３０が、二次電池１０のＳＯＣの補正を、二次電池１０を満放電状態から充電した際の二次電池１０のＳＯＣと、二次電池１０の充電量Ｑを二次電池１０の電圧Ｖで微分して得たｄＱ／ｄＶとの関係を示すＳＯＣ－ｄＱ／ｄＶ曲線に基づいて行なうことによって、二次電池１０のＳＯＣをより高い精度で推定することができる。 Further, in the battery pack 100 according to the present embodiment, the control system 30 corrects the SOC of the secondary battery 10 with the SOC of the secondary battery 10 when the secondary battery 10 is charged from a fully discharged state. By performing the charge amount Q of the secondary battery 10 based on the SOC−dQ / dV curve showing the relationship with the dQ / dV obtained by differentiating the charge amount Q of the secondary battery 10 with the voltage V of the secondary battery 10, the SOC of the secondary battery 10 can be further increased. It can be estimated with high accuracy.

　図８は、本実施形態に係る二次電池の制御方法によって補正されたＳＯＣを検証する手順の一例を示すフローチャートである。 FIG. 8 is a flowchart showing an example of a procedure for verifying the SOC corrected by the control method of the secondary battery according to the present embodiment.

　先ず、準備段階として、一又は複数のリチウムイオン二次電池セルを有する二次電池と、制御部と、安全機構とを含むバッテリーマネジメントシステムを用意する。用意した二次電池に対し、例えば室温で０．２Ｃのレートで満放電をおこない、その後、室温で０．２Ｃのレートで満充電をおこない、蓄電池を実使用の初期状態とする。この充電の際に、各電圧におけるｄＱ／ｄＶ値を得てＱを算出し、初期状態のＳＯＣ－ｄＱ／ｄＶ曲線を取得すると共に、制御部のソフトウェア上のＳＯＣを記録する。 First, as a preparatory step, a battery management system including a secondary battery having one or more lithium ion secondary battery cells, a control unit, and a safety mechanism is prepared. The prepared secondary battery is fully discharged at a rate of 0.2 C at room temperature, for example, and then fully charged at a rate of 0.2 C at room temperature to bring the storage battery into the initial state of actual use. At the time of this charging, the dQ / dV value at each voltage is obtained, Q is calculated, the SOC-dQ / dV curve in the initial state is acquired, and the SOC on the software of the control unit is recorded.

　上記の過程で初期状態となった蓄電池を意図的に劣化させるため、例えば１００サイクル充放電工程を行う。１００サイクル充放電工程では、例えば、４５℃の温度環境下において０．５Ｃのレートで満放電とした後に、０．５Ｃのレートで満充電をおこなう、というサイクルを１００回繰り返す。 In order to intentionally deteriorate the storage battery that was in the initial state in the above process, for example, a 100-cycle charge / discharge process is performed. In the 100-cycle charge / discharge step, for example, in a temperature environment of 45 ° C., a full discharge is performed at a rate of 0.5 C, and then a full charge is performed at a rate of 0.5 C, which is repeated 100 times.

　その後、二次電池で充電を開始し（ステップＳ１１）、二次電池の充電電圧及び電流値を検出し（ステップＳ１２）、電流積算値を求める（ステップＳ１３）。求めた電流積算値から電気量Ｑを求め（ステップＳ１４）、更にｄＱ／ｄＶの値を算出する（ステップＳ１５）。 After that, charging is started with the secondary battery (step S11), the charging voltage and current value of the secondary battery are detected (step S12), and the current integrated value is obtained (step S13). The amount of electricity Q is obtained from the obtained integrated current value (step S14), and the value of dQ / dV is further calculated (step S15).

　次に、第３点（極値点（Ｐ３））に至ったか否かを判定し（ステップＳ１６）、第３点に至った場合、二次電池のＳＯＣがＳＯＣ補正手段５２によって補正されたか否かを判定する（ステップＳ１７）。二次電池のＳＯＣが補正されたときは、補正された当該位置（Ｐ３’に相当）でのｄＱ／ｄＶ_Ｐ３’を取得する（ステップＳ１８）。次いで、第１点（極値点（Ｐ２））における充電量Ｑ_１ｓｔと第２点（極値点（Ｂ２））における充電量Ｑ_２ｎｄとの差であるΔＱを算出し（ステップＳ１９）、得られたｄＱ／ｄＶ_Ｐ３’及びΔＱと、第３点でのｄＱ／ｄＶ_３ｒｄの値と、二次電池の初期状態の満充電容量Ｑ_ｆとを用いて、上記式（１）でＰ３’を算出する（ステップ２０）。そして、補正された当該位置（Ｐ３’に相当）と、上記式（１）から得られたＰ３’を比較し、定数Ａが上記式（１）で規定された所定範囲内であることを確認する（ステップＳ２１）。この検証手順により、補正手段３４によるＳＯＣ補正が適正に行われていると判断することができる。 Next, it is determined whether or not the third point (extreme value point (P3)) has been reached (step S16), and when the third point is reached, whether or not the SOC of the secondary battery has been corrected by the SOC correction means 52. (Step S17). When SOC of the rechargeable battery is corrected to obtain a corrected the position 'dQ / _{dV P3} in (corresponding to _P3)' (step S18). Then, the first point to calculate the ΔQ is the difference between the charge amount _{Q 2nd} in the charge amount _{Q 1st} and second points (extreme points (B2)) in (extreme points (P2)) (step S19), to give dQ / _{dV P3} is _'and and Delta] Q, and the value of dQ _{/ dV 3rd} in the third point, by using the full charge capacity _{Q f} of the initial state of the secondary battery, P3 by the above formula (1)' the Calculate (step 20). Then, the corrected position (corresponding to P3') is compared with P3' obtained from the above formula (1), and it is confirmed that the constant A is within the predetermined range defined by the above formula (1). (Step S21). By this verification procedure, it can be determined that the SOC correction by the correction means 34 is properly performed.

　以上、本発明の実施形態について図面を参照して詳述したが、各実施形態における各構成及びそれらの組み合わせ等は一例であり、本発明の趣旨から逸脱しない範囲内で、構成の付加、省略、置換、及びその他の変更が可能である。 Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in the respective embodiments are examples, and the configurations are added or omitted within the range not deviating from the gist of the present invention. , Replacements, and other changes are possible.

［実施例１］
（１）二次電池の作製
　二次電池としてリチウムイオン二次電池を作製した。
　正極は次のようにして作製した。まず、正極を準備した。正極活物質としてＬｉＦｅ_０．９Ｍｇ_０．１ＰＯ_４、導電助剤としてカーボンブラック、バインダーとしてポリフッ化ビニリデン（ＰＶＤＦ）を準備した。これらの材料を溶媒中で混合し、塗料を作製し、アルミ箔からなる正極集電体上に塗布した。正極活物質と導電助材とバインダーの質量比は、９５：２：３とした。塗布後に、溶媒は除去した。正極活物質層の担持量が１０ｍｇ／ｃｍ^２の正極シートを作製した。 [Example 1]
(1) Preparation of secondary battery A lithium ion secondary battery was manufactured as a secondary battery.
The positive electrode was prepared as follows. First, a positive electrode was prepared. _{LiFe 0.9} Mg _0.1 PO ₄ was prepared as the positive electrode active material, carbon black was prepared as the conductive auxiliary agent, and polyvinylidene fluoride (PVDF) was prepared as the binder. These materials were mixed in a solvent to prepare a paint, which was applied onto a positive electrode current collector made of aluminum foil. The mass ratio of the positive electrode active material, the conductive auxiliary material, and the binder was 95: 2: 3. After coating, the solvent was removed. A positive electrode sheet having a supported amount of the positive electrode active material layer of 10 mg / cm ^{2 was prepared.}

　負極は、次のようにして作製した。負極活物質として黒鉛、バインダーとしてスチレン・ブタジエンゴム（ＳＢＲ）、増粘剤としてカルボキシメチルセルロース（ＣＭＣ）を準備した。これらの材料を蒸留水に分散させ、塗料を作製し、銅箔からなる負極集電体上に塗布した。負極活物質とバインダー及び増粘剤は質量比で９５：３：２とした。塗布後に乾燥させ、負極活物質層の担持量が１０ｍｇ／ｃｍ^２の負極シートを作製した。 The negative electrode was produced as follows. Graphite was prepared as the negative electrode active material, styrene-butadiene rubber (SBR) was prepared as the binder, and carboxymethyl cellulose (CMC) was prepared as the thickener. These materials were dispersed in distilled water to prepare a paint, which was applied onto a negative electrode current collector made of copper foil. The mass ratio of the negative electrode active material, the binder and the thickener was 95: 3: 2. After coating, it was dried to prepare a negative electrode sheet having a loading amount of the negative electrode active material layer of 10 mg / cm ^2.

　上記で作製した正極シートと負極シートを、セパレータを介して積層して発電部を作製した。セパレータには、ポリエチレンとポリプロピレンの積層体を用いた。得られた発電部を電解液に含浸させてから外装体内に封入した後、真空シールし、リチウムイオン二次電池を作製した。電解液は、エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＥＣ）が等量混合された溶媒に、六フッ化リン酸リチウム（ＬｉＰＦ_６）１．５ｍｏｌ／Ｌを溶解させたものを用いた。 The positive electrode sheet and the negative electrode sheet produced above were laminated via a separator to produce a power generation unit. A laminate of polyethylene and polypropylene was used as the separator. The obtained power generation unit was impregnated with an electrolytic solution, sealed in the exterior body, and then vacuum-sealed to prepare a lithium ion secondary battery. As the electrolytic solution, 1.5 mol / L of _{lithium hexafluorophosphate (LiPF 6} ) was dissolved in a solvent in which equal amounts of ethylene carbonate (EC) and dimethyl carbonate (DEC) were mixed.

（２）電池パックの作製
　上記（１）で作製したリチウムイオン二次電池に、定電流充電装置と制御システムとをそれぞれ接続して電池パックを作製した。制御システムは、クーロンカウンター及び電圧計測器を有する検出手段と、ｄＱ／ｄＶ算出手段、抽出手段と、補正手段と、記憶手段と、ＳＯＣ表示手段とを有する。 (2) Preparation of Battery Pack A battery pack was produced by connecting a constant current charging device and a control system to the lithium ion secondary battery produced in (1) above. The control system includes a detection means having a coulomb counter and a voltage measuring instrument, a dQ / dV calculation means, an extraction means, a correction means, a storage means, and an SOC display means.

（３）ＳＯＣ－ｄＱ／ｄＶ曲線の作成
　電池パックのリチウムイオン二次電池を、０．１Ｃに相当する定電流で終止電圧３．６Ｖまで充電し、その後０．１Ｃに相当する定電流で２．６Ｖまで放電した。充放電は２５℃の環境下に行なった。リチウムイオン二次電池の充放電を行ないながら、クーロンカウンターと電圧計測器を用いて充電量Ｑと電圧値Ｖを測定した。そして、ｄＱ／ｄＶ算出部にて、ｄＱ／ｄＶを算出し、ＳＯＣ－ｄＱ／ｄＶ曲線を作成した。また、リチウムイオン二次電池の初期状態の満充電容量Ｑ_ｆを測定した。そして、定数Ａを０．１として上記式（１）の補正時期算出項から補正ＳＯＣ値を算出し、補正ＳＯＣ値を６８％とした。 (3) Creation of SOC-dQ / dV curve The lithium-ion secondary battery in the battery pack is charged with a constant current corresponding to 0.1C to a final voltage of 3.6V, and then 2 at a constant current corresponding to 0.1C. It was discharged to 0.6V. Charging and discharging was performed in an environment of 25 ° C. While charging and discharging the lithium ion secondary battery, the charge amount Q and the voltage value V were measured using a coulomb counter and a voltage measuring instrument. Then, the dQ / dV calculation unit calculated the dQ / dV and created the SOC-dQ / dV curve. _{In addition, the full charge capacity Q f} in the initial state of the lithium ion secondary battery was measured. Then, the corrected SOC value was calculated from the correction timing calculation term of the above formula (1) with the constant A set to 0.1, and the corrected SOC value was set to 68%.

（４）評価
　上記（３）ＳＯＣ－ｄＱ／ｄＶ曲線の作成と同じ条件でリチウムイオン二次電池の充放電サイクルを行なった。５００サイクル目の充電時に、充電しながら、第１点（極値点（Ｐ２））と第２点（極値点（Ｐ３））とを抽出した。第１点（極値点（Ｐ２））における充電量Ｑ_１ｓｔと、第２点（極値点（Ｂ２））における充電量Ｑ_２ｎｄと、第３点（極値点（Ｐ３））におけるｄＱ／ｄＶ_３ｒｄとを読み取り、定数Ａを０．１として、上記式（１）の補正時期算出項により補正時期を算出した。そして、リチウムイオン二次電池のｄＱ／ｄＶがその補正時期となった時点でＳＯＣ値を補正ＳＯＣ値とした。満充電容量まで充電を行い、ＳＯＣ－ｄＱ／ｄＶ曲線および実測ＳＯＣ値を取得した。補正ＳＯＣ値と実測ＳＯＣ値の差分を推定誤差とした。その結果を下記の表１に示す。 (4) Evaluation The charge / discharge cycle of the lithium ion secondary battery was carried out under the same conditions as in the above (3) SOC-dQ / dV curve preparation. At the time of charging in the 500th cycle, the first point (extreme point (P2)) and the second point (extreme point (P3)) were extracted while charging. A charge amount _{Q 1st} in the first point (extreme point (P2)), a charge amount _{Q 2nd} in the second point (extreme point (B2)), dQ in the third point (extreme point (P3)) / The dV _3rd was read, the constant A was set to 0.1, and the correction time was calculated by the correction time calculation term of the above equation (1). Then, when the dQ / dV of the lithium ion secondary battery reached the correction time, the SOC value was set as the corrected SOC value. The battery was charged to the full charge capacity, and the SOC-dQ / dV curve and the measured SOC value were obtained. The difference between the corrected SOC value and the measured SOC value was used as the estimation error. The results are shown in Table 1 below.

［実施例２］
　上記（３）補正ＳＯＣ値の設定において定数Ａを０．５とし、（４）の評価において定数Ａを０．５としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す [Example 2]
The corrected SOC value and the estimation error are the same as in the first embodiment except that the constant A is set to 0.5 in the setting of the above (3) corrected SOC value and the constant A is set to 0.5 in the evaluation of (4). And was measured. The results are shown in Table 1 below.

［実施例３］
　上記（３）補正ＳＯＣ値の設定において定数Ａを１とし、（４）の評価において定数Ａを１としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Example 3]
The corrected SOC value and the estimation error were measured in the same manner as in Example 1 except that the constant A was set to 1 in the setting of the above (3) corrected SOC value and the constant A was set to 1 in the evaluation of (4). .. The results are shown in Table 1 below.

［実施例４］
　上記（３）補正ＳＯＣ値の設定において定数Ａを５とし、（４）の評価において定数Ａを５としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Example 4]
The corrected SOC value and the estimation error were measured in the same manner as in Example 1 except that the constant A was set to 5 in the setting of the above (3) corrected SOC value and the constant A was set to 5 in the evaluation of (4). .. The results are shown in Table 1 below.

［実施例５］
　上記（３）補正ＳＯＣ値の設定において定数Ａを７とし、（４）の評価において定数Ａを７としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Example 5]
The corrected SOC value and the estimation error were measured in the same manner as in Example 1 except that the constant A was set to 7 in the setting of the above (3) corrected SOC value and the constant A was set to 7 in the evaluation of (4). .. The results are shown in Table 1 below.

［実施例６］
　上記（３）補正ＳＯＣ値の設定において定数Ａを１０とし、（４）の評価において定数Ａを１０としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Example 6]
The corrected SOC value and the estimation error were measured in the same manner as in Example 1 except that the constant A was set to 10 in the setting of the above (3) corrected SOC value and the constant A was set to 10 in the evaluation of (4). .. The results are shown in Table 1 below.

［比較例１］
　上記（３）補正ＳＯＣ値の設定において定数Ａを０とし、（４）の評価において、定数Ａを０としたこと、すなわち、第３点（極値点（Ｐ３））を補正時期としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Comparative Example 1]
In the above (3) setting of the corrected SOC value, the constant A was set to 0, and in the evaluation of (4), the constant A was set to 0, that is, the third point (extreme value point (P3)) was set as the correction time. Except for the above, the corrected SOC value and the estimation error were measured in the same manner as in Example 1. The results are shown in Table 1 below.

［比較例２］
　上記（３）補正ＳＯＣ値の設定において、定数Ａを１１とし、（４）の評価において、定数Ａを１１としたこと以外は、実施例１と同様にして、補正ＳＯＣ値と推定誤差とを測定した。その結果を下記の表１に示す。 [Comparative Example 2]
The corrected SOC value and the estimation error are set in the same manner as in the first embodiment except that the constant A is set to 11 in the setting of the above (3) corrected SOC value and the constant A is set to 11 in the evaluation of (4). It was measured. The results are shown in Table 1 below.

　　　　　　　　　　　　　　　　　

　　　　　　　　　　　　　　　　　

　表１に示すように、定数Ａが本発明の範囲内にある実施例１～４では、推定誤差が３％以下と低く、充電中に二次電池のＳＯＣを高い精度で推定することができることが確認された。これに対して、定数Ａが本発明の範囲よりも小さい比較例１及び定数Ａが本発明の範囲よりも大きい比較例２では、推定誤差が６％、７％と顕著に大きくなった。 As shown in Table 1, in Examples 1 to 4 in which the constant A is within the range of the present invention, the estimation error is as low as 3% or less, and the SOC of the secondary battery can be estimated with high accuracy during charging. Was confirmed. On the other hand, in Comparative Example 1 in which the constant A was smaller than the range of the present invention and Comparative Example 2 in which the constant A was larger than the range of the present invention, the estimation errors were remarkably large at 6% and 7%.

１　セパレータ
２　正極
２Ａ　正極集電体
２Ｂ　正極活物質層
３　負極
３Ａ　負極集電体
３Ｂ　負極活物質層
４　発電素子
５　外装体
５Ａ　金属箔
５Ｂ　樹脂層
６　端子
１０　二次電池
２０　充電手段
３０　制御システム
３１　検出手段
３２　ｄＱ／ｄＶ算出手段
３３　抽出手段
３４　補正手段
３５　記憶手段
１００　電池パック 1 Separator 2 Positive electrode 2A Positive electrode current collector 2B Positive electrode active material layer 3 Negative electrode 3A Negative electrode current collector 3B Negative electrode active material layer 4 Power generation element 5 Exterior 5A Metal foil 5B Resin layer 6 Terminal 10 Secondary battery 20 Charging means 30 Control system 31 Detection means 32 dQ / dV calculation means 33 Extraction means 34 Correction means 35 Storage means 100 Battery pack

Claims (6)

1. 　二次電池の充電電圧と、前記二次電池の充電電圧の変化量に対する蓄電量の変化量の割合であるｄＱ／ｄＶとの関係を示すＶ－ｄＱ／ｄＶ曲線において、前記二次電池の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極大値若しくは前記極大値と数学的に等価な点を第１点とし、
   　前記二次電池の電圧Ｖが３．３５Ｖ以上３．３９Ｖ以下の範囲内に現れる下降から上昇に転じる最後の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極小値若しくは前記極小値と数学的に等価な点を第２点とし、
   　前記二次電池の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて３番目に現れる極大値若しくは前記極大値と数学的に等価な点を第３点とし、
   　前記第１点における充電量Ｑ_１ｓｔと、前記第２点における充電量Ｑ_２ｎｄとの差をΔＱとし、
   　前記二次電池のＳＯＣを、下記の式（１）で求められるＮへ補正する、二次電池の制御システム。
   Ｎ＝ＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝　　　・・・（１）
   　但し、式（１）において、ｄＱ／ｄＶ_３ｒｄは、前記第３点における前記二次電池の電圧の変化量に対する充電量の変化量の割合を表し、Ｑ_ｆは、前記二次電池の初期状態の満充電容量を表し、Ａは、０．１≦Ａ≦１０を満足する数を表す。 In the V-dQ / dV curve showing the relationship between the charging voltage of the secondary battery and dQ / dV, which is the ratio of the amount of change in the amount of electricity stored to the amount of change in the charging voltage of the secondary battery, the voltage of the secondary battery. The first pole point where V appears in the range of 3.34V or more and less than 3.38V, which changes from rising to falling, the point mathematically equivalent to the pole value point, or the maximum that appears second from the low voltage side. The first point is the value or the point that is mathematically equivalent to the maximum value.
   The voltage V of the secondary battery appears in the range of 3.35 V or more and 3.39 V or less, and is the last extremum point that changes from falling to rising, the point mathematically equivalent to the extremum point, or counting from the low voltage side. The second point is the minimum value that appears second or the point that is mathematically equivalent to the minimum value.
   The first extremum point where the voltage V of the secondary battery appears in the range of 3.38V or more and 3.42V or less and changes from ascending to descending, or a point mathematically equivalent to the extremum point, or counting from the low voltage side. The third point is the maximum value that appears third or the point that is mathematically equivalent to the maximum value.
   Let ΔQ be the difference between the charge amount Q _{1st at} the first point and the charge amount Q _{2nd at the second point.}
   A secondary battery control system that corrects the SOC of the secondary battery to N obtained by the following formula (1).
   N = SOC {(dQ / dV _3rd ) / Q _f −ΔQ * A} ・ ・ ・ (1)
   However, in the formula (1), dQ / dV _3rd represents the ratio of the change amount of the charge amount to the change amount of the voltage of the secondary battery at the third point, and Q _f is the initial state of the secondary battery. Represents the full charge capacity of, and A represents a number satisfying 0.1 ≦ A ≦ 10.
2. 　前記二次電池のＳＯＣの補正を、前記二次電池を満放電状態から充電した際の前記二次電池のＳＯＣと、前記二次電池の充電量Ｑを前記二次電池の電圧Ｖで微分して得たｄＱ／ｄＶとの関係を示すＳＯＣ－ｄＱ／ｄＶ曲線に基づいて行なう、請求項１に記載の二次電池の制御システム。 To correct the SOC of the secondary battery, the SOC of the secondary battery when the secondary battery is charged from a fully discharged state and the charge amount Q of the secondary battery are differentiated by the voltage V of the secondary battery. The secondary battery control system according to claim 1, which is performed based on the SOC-dQ / dV curve showing the relationship with the dQ / dV obtained.
3. 　前記二次電池の充電量Ｑと前記二次電池の電圧Ｖとを検出する検出手段と、
   　前記第１点、前記第２点及び前記第３点を抽出する抽出手段と、
   　前記第１点における充電量Ｑ_１ｓｔと前記第２点における充電量Ｑ_２ｎｄとの差であるΔＱを算出すると共に、前記二次電池のＳＯＣを前記式（１）で求められるＮへ補正する補正手段と、を有する、請求項１又は２に記載の二次電池の制御システム。 A detection means for detecting the charge amount Q of the secondary battery and the voltage V of the secondary battery,
   An extraction means for extracting the first point, the second point, and the third point, and
   Correction that calculates ΔQ, which is the difference between the charge amount Q _1st at the first point and the charge amount Q _{2nd at} the second point, and corrects the SOC of the secondary battery to N obtained by the equation (1). The secondary battery control system according to claim 1 or 2, comprising means.
4. 　二次電池と、請求項１～３のいずれか一項に記載の二次電池の制御システムと、を備える、電池パック。 A battery pack including a secondary battery and the control system for the secondary battery according to any one of claims 1 to 3.
5. 　前記二次電池は、正極と負極とを有し、
   　前記正極は、活物質として、一般式ＬｉＦｅ_１－ＸＭ_ＸＰＯ_４で表されるリン酸鉄リチウム化合物を含み（但し、Ｍは、Ｍｎ，Ｃｒ，Ｃｏ，Ｃｕ，Ｎｉ，Ｖ，Ｍｏ，Ｔｉ，Ｚｎ，Ａｌ，Ｇａ，Ｍｇ，Ｂ，Ｎｂからなる群より選ばれる少なくとも一つの元素であり、ｘは、０≦Ｘ≦０．５を満たす数である）、
   　前記負極は、活物質として黒鉛を含む、請求項４に記載の電池パック。 The secondary battery has a positive electrode and a negative electrode, and has a positive electrode and a negative electrode.
   The positive electrode, the active material comprises a formula _{LiFe 1-X} M _X PO lithium iron phosphate compound represented by ₄ (where, M is, Mn, Cr, Co, Cu , Ni, V, Mo, Ti , Zn, Al, Ga, Mg, B, Nb, at least one element selected from the group, x is a number satisfying 0 ≦ X ≦ 0.5),
   The battery pack according to claim 4, wherein the negative electrode contains graphite as an active material.
6. 　二次電池の充電電圧と、前記二次電池の充電電圧の変化量に対する蓄電量の変化量の割合であるｄＱ／ｄＶとの関係を示すＶ－ｄＱ／ｄＶ曲線において、前記二次電池の電圧Ｖが３．３４Ｖ以上３．３８Ｖ未満の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極大値若しくは前記極大値と数学的に等価な点を第１点とし、
   　前記二次電池の電圧Ｖが３．３５Ｖ以上３．３９Ｖ以下の範囲内に現れる下降から上昇に転じる最後の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて２番目に現れる極小値若しくは前記極小値と数学的に等価な点を第２点とし、
   　前記二次電池の電圧Ｖが３．３８Ｖ以上３．４２Ｖ以下の範囲内に現れる上昇から下降に転じる最初の極値点若しくは前記極値点と数学的に等価な点、又は低電圧側から数えて３番目に現れる極大値若しくは前記極大値と数学的に等価な点を第３点とし、
   　前記第１点における充電量Ｑ_１ｓｔと、前記第２点における充電量Ｑ_２ｎｄとの差をΔＱとし、
   　前記二次電池のＳＯＣを、下記の式（１）で求められるＮへ補正する、二次電池の制御方法。
   Ｎ＝ＳＯＣ｛（ｄＱ／ｄＶ_３ｒｄ）／Ｑ_ｆ－ΔＱ＊Ａ｝　　　・・・（１）
   　但し、式（１）において、ｄＱ／ｄＶ_３ｒｄは、前記第３点における前記二次電池の電圧の変化量に対する充電量の変化量の割合を表し、Ｑ_ｆは、前記二次電池の初期状態の満充電容量を表し、Ａは、０．１≦Ａ≦１０を満足する数を表す。 In the V-dQ / dV curve showing the relationship between the charging voltage of the secondary battery and dQ / dV, which is the ratio of the amount of change in the amount of electricity stored to the amount of change in the charging voltage of the secondary battery, the voltage of the secondary battery. The first pole point where V appears in the range of 3.34V or more and less than 3.38V, which changes from rising to falling, the point mathematically equivalent to the pole value point, or the maximum that appears second from the low voltage side. The first point is the value or the point that is mathematically equivalent to the maximum value.
   The voltage V of the secondary battery appears in the range of 3.35 V or more and 3.39 V or less, and is the last extremum point that changes from falling to rising, the point mathematically equivalent to the extremum point, or counting from the low voltage side. The second point is the minimum value that appears second or the point that is mathematically equivalent to the minimum value.
   The first extremum point where the voltage V of the secondary battery appears in the range of 3.38V or more and 3.42V or less and changes from ascending to descending, or a point mathematically equivalent to the extremum point, or counting from the low voltage side. The third point is the maximum value that appears third or the point that is mathematically equivalent to the maximum value.
   Let ΔQ be the difference between the charge amount Q _{1st at} the first point and the charge amount Q _{2nd at the second point.}
   A method for controlling a secondary battery, in which the SOC of the secondary battery is corrected to N obtained by the following formula (1).
   N = SOC {(dQ / dV _3rd ) / Q _f −ΔQ * A} ・ ・ ・ (1)
   However, in the formula (1), dQ / dV _3rd represents the ratio of the change amount of the charge amount to the change amount of the voltage of the secondary battery at the third point, and Q _f is the initial state of the secondary battery. Represents the full charge capacity of, and A represents a number satisfying 0.1 ≦ A ≦ 10.

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