JP3669202B2 - Battery status monitoring device - Google Patents

Battery status monitoring device Download PDF

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Publication number
JP3669202B2
JP3669202B2 JP11257099A JP11257099A JP3669202B2 JP 3669202 B2 JP3669202 B2 JP 3669202B2 JP 11257099 A JP11257099 A JP 11257099A JP 11257099 A JP11257099 A JP 11257099A JP 3669202 B2 JP3669202 B2 JP 3669202B2
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battery
current
capacity
battery capacity
voltage
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JP2000306613A (en
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典彦 枚田
達夫 阿部
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Nissan Motor Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Description

【０００１】
【発明の属する技術分野】
本発明は、車載バッテリの充放電状態を監視するバッテリ状態監視装置に関する。
【０００２】
【従来の技術】
従来、特にパラレルハイブリッド電気自動車（ＰＨＥＶ）に搭載されているリチウムイオンバッテリの充放電状態を監視するバッテリ状態監視装置では、バッテリの充放電電圧と充放電電流とから開放電圧ＯＣＶを推定し、さらにこの開放電圧からバッテリ容量ＳＯＣを推定し、このバッテリ容量推定値を諸々の制御に利用している。
【０００３】
つまり、図４に示すように、バッテリの開放電圧ＯＣＶは、検出されるバッテリ電圧Ｖｂとバッテリ電流Ｉｂ、そして２点のバッテリ電圧Ｖb1，Ｖb2とバッテリ電流Ｉb1，Ｉb2とから求めることができる内部抵抗Ｒｎとから、次のようにして求める。
【０００４】
ＯＣＶ＝Ｖｂ＋Ｉｂ・Ｒｎ
だたし、内部抵抗Ｒｎは、Ｒｎ＝（Ｖb2−Ｖb1）／（Ｉb2−Ｉb1）で求められる。
【０００５】
そして、リチウムイオンバッテリの場合、バッテリの開放電圧ＯＣＶとバッテリ容量ＳＯＣとは、図５に示すような相関関係があり、ＯＣＶからＳＯＶを一義的に決定する。
【０００６】
【発明が解決しようとする課題】
ところが、このような従来のバッテリ状態監視装置の場合、次のような問題点があった。リチウムイオンバッテリでは、図６に示すように、放電率により内部抵抗が変化し、その変化の挙動は放電率が小さい間は放電サイクルそれぞれにおいてほぼリニアであるが、たとえば、３０Ａを超えるような大きな放電率になると内部抵抗を厳密に規定することができなくなる。そのため、開放電圧ＯＣＶが正確に求められず、結果的にバッテリ容量ＳＯＣも正確に推定することができなくなる問題点があった。
【０００７】
本発明はこのような従来の問題点に鑑みてなされたもので、放電率が大きい場合にも正確にバッテリ容量を推定することができるバッテリ状態監視装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
請求項１の発明のバッテリ状態監視装置は、リチウムイオンバッテリの状態を監視するバッテリ監視装置において、バッテリ電流を検出する電流検出手段と、バッテリ電圧を検出する電圧検出手段と、前記電流検出手段の検出した前記バッテリ電流と前記電圧検出手段の検出した前記バッテリ電圧とに基づいて、バッテリの内部抵抗を演算する内部抵抗演算手段と、前記バッテリ電流、前記バッテリ電圧及び前記内部抵抗を用いてバッテリ開放電圧を演算する開放電圧演算手段と、前記開放電圧演算手段の算出した前記バッテリ開放電圧からバッテリ容量を推定するバッテリ容量推定手段と、前記バッテリ電流を用いて電流容量を積算する電流容量演算手段と、前記バッテリ電流が所定範囲内にある場合には前記バッテリ容量推定手段の推定する前記バッテリ容量を最終バッテリ容量とし、前記バッテリ電流が前記所定範囲外である場合には当該所定範囲外に逸脱する直前に前記バッテリ容量推定手段の推定したバッテリ容量に対して、当該所定範囲外に逸脱した時点以降に前記電流容量演算手段の積算した電流容量を加算して最終バッテリ容量として出力するバッテリ容量補正手段とを備えたものである。
【０００９】
請求項２の発明のバッテリ状態監視装置は、請求項１において、前記バッテリ容量補正手段が、前記内部抵抗の電流依存変化率がほぼ一定の範囲を前記バッテリ電流の所定範囲としたものである。
【００１０】
請求項１及び２の発明のバッテリ状態監視装置では、内部抵抗演算手段により電流検出手段の検出したバッテリ電流と電圧検出手段の検出したバッテリ電圧とに基づいてバッテリの内部抵抗を演算し、また開放電圧演算手段によりバッテリ電流検出手段の検出するバッテリ電流、バッテリ電圧検出手段の検出するバッテリ電圧及び前記内部抵抗を用いてバッテリ開放電圧を演算し、さらに、バッテリ容量推定手段がこの開放電圧演算手段の算出したバッテリ開放電圧からバッテリ容量を推定する。一方、電流容量演算手段が電流検出手段の検出するバッテリ電流を用いて電流容量を積算する。
【００１１】
そして、バッテリ容量補正手段は、バッテリ電流が所定範囲内にある場合にはバッテリ容量推定手段の推定するバッテリ容量を最終バッテリ容量とし、バッテリ電流が所定範囲外である場合には当該所定範囲外に逸脱する直前にバッテリ容量推定手段の推定したバッテリ容量に対して、当該所定範囲外に逸脱した時点以降に電流容量演算手段の積算した電流容量を加算して最終バッテリ容量として出力する。
【００１２】
これにより、バッテリ電流がバッテリの内部抵抗の変化率がほぼ一定となる所定範囲内にある場合にはバッテリ開放電圧からバッテリ容量を正確に推定して最終バッテリ容量として出力し、また、バッテリ電流がバッテリの内部抵抗の変化率がほぼ一定となる所定範囲を逸脱した場合にはその範囲を逸脱する直前のバッテリ開放電圧から推定したバッテリ容量に対して、所定範囲を逸脱した後の電流容量の積算値を加算する補正を行って最終バッテリ容量として出力することができ、バッテリ電流の変化が激しい使用状態でも正確なバッテリ容量監視が可能である。
【００１３】
請求項３の発明のバッテリ状態監視装置は、請求項１又は２において、前記バッテリ容量補正手段が、前記バッテリ電流が前記所定範囲内に復帰したときに、前記最終バッテリ容量を前記バッテリ容量推定手段の推定する前記バッテリ容量にリセットするようにしたものであり、放電率の変化が激しい使用状態の後でもバッテリ容量を正確に監視できる。
【００１４】
【発明の効果】
請求項１及び２の発明によれば、リチウムイオンバッテリの状態を監視するバッテリ監視装置において、バッテリ電流がバッテリの内部抵抗の変化率がほぼ一定となる所定範囲内にある場合にはバッテリ開放電圧からバッテリ容量を正確に推定して最終バッテリ容量として出力し、また、バッテリ電流がバッテリの内部抵抗の変化率がほぼ一定となる所定範囲を逸脱した場合にはその範囲を逸脱する直前のバッテリ開放電圧から推定したバッテリ容量に対して、所定範囲を逸脱した後の電流容量の積算値を加算する補正を行って最終バッテリ容量として出力することができ、バッテリ電流の変化が激しい使用状態でも正確なバッテリ容量監視が可能である。
【００１５】
請求項３の発明によれば、請求項１又は２の発明の効果に加えて、バッテリ電流が所定範囲内に復帰したときに、最終バッテリ容量としてバッテリ容量推定手段の推定するバッテリ容量にリセットするようにしたので、放電率の変化が激しい使用状態の後でもバッテリ容量を正確に監視できる。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態を図に基づいて詳説する。図１は本発明の１つの実施の形態の構成を示している。この実施の形態のバッテリ状態監視装置は、バッテリ１から負荷２に流れるバッテリ電流Ｉｂを検出する電流計３、バッテリ電圧Ｖｂを検出する電圧計４、このバッテリ電流Ｉｂ、バッテリ電圧Ｖｂを入力してバッテリ容量ＳＯＣを演算し、エンジン５その他の諸々の機器を制御するコントローラ６、エンジン５の駆動によって発電し、バッテリ１に充電電流を供給する発電機７を備えている。なお、パラレルハイブリッド電気自動車ＰＨＥＶの場合、エンジン５の回転出力は直接、自動車を走行駆動するために利用される。
【００１７】
図２には、コントローラ６におけるバッテリ容量演算回路の構成が示してある。バッテリ容量演算回路は、全体の制御を行う演算制御部１１、バッテリ電流Ｉｂとバッテリ電圧Ｖｂから開放電圧ＯＣＶを求めるＯＣＶ演算部１２、ＯＣＶ−ＳＯＣの相関特性データを内蔵し、ＯＣＶ演算部１２から出力される開放電圧ＯＣＶに対応するバッテリ容量ＳＯＣを推定して出力するＳＯＣ換算部１３、バッテリ電流Ｉｂを時間積算することによって電流容量ΣＡ（ｈ）を演算する電流容量演算部１４、演算制御部１１の指示によりＳＯＣ換算部１３からのバッテリ容量推定値ＳＯＣに対して電流容量演算部１４からの電流容量ΣＡ（ｈ）を用いて補正を行い最終的なバッテリ容量ＳＯＣを求めるＳＯＣ補正部１５、そして最終的なバッテリ容量ＳＯＣを出力するＳＯＣ出力部１６から構成されている。
【００１８】
次に、上記構成のバッテリ状態監視装置の動作を説明する。この実施の形態の場合、図３に示すように、開放電圧ＯＣＶから換算したバッテリ容量ＳＯＣを直接に最終バッテリ容量ＳＯＣとして使用する領域を、放電率が−１０Ａ〜１０Ａの範囲に設定している。なお、この領域は、従来例のところで説明したように、図６に示したグラフにおいて、リチウムイオンバッテリの放電率の変化による内部抵抗の変化率がほぼ一定である範囲、−３０Ａ〜＋３０Ａ程度の範囲内に設定することができる。 ＯＣＶ演算部１２はバッテリ電流計３の検出するバッテリ電流Ｉｂ（放電時プラス（＋）、充電時マイナス（−）とする）、バッテリ電圧計４の検出するバッテリ電圧Ｖｂを所定の周期で取り込む。そして、これまでに取り込んだ有効な２組のバッテリ電流とバッテリ電圧との検出値（ここで採用する検出値は内部抵抗を有効に演算できる２組の検出値を採用する）Ｉb1，Ｉb2；Ｖb1，Ｖb2により、上述した式によって内部抵抗Ｒｎを求めておき、新たに取り込んだバッテリ電流Ｉｂとバッテリ電圧Ｖｂにより、開放電圧ＯＣＶを、
ＯＣＶ＝Ｖｂ＋Ｉｂ・Ｒｎ
によって求め、ＳＯＣ換算部１３に出力する。
【００１９】
ＳＯＣ換算部１３では、内蔵する図５に示した開放電圧ＯＣＶ−バッテリ容量ＳＯＣ相関特性データを参照し、入力されるバッテリ開放電圧ＯＣＶに対応するバッテリ容量ＳＯＣを求めて出力する。
【００２０】
演算制御部１１はバッテリ電流Ｉｂを監視していて、このバッテリ電流Ｉｂが上述した所定の電流範囲を逸脱した場合、電流容量演算部１４に積算指令を与え、またＳＯＣ補正部１５に補正指令を与える。
【００２１】
そして、電流容量演算部１４は、入力されるバッテリ電流Ｉｂの時間積分を行って電流容量積算値ΣＡ（ｈ）を求めてＳＯＣ補正部１５に出力する。ＳＯＣ補正部１５は、制御演算部１１から補正指令がない場合にはＳＯＣ換算部１３からのバッテリ容量ＳＯＣを最終バッテリ容量としてＳＯＣ出力部１６に出力し、制御演算部１１から補正指令を受け取ると、ＳＯＣ換算部１３からのバッテリ容量換算値ＳＯＣに対して、電流容量演算部１４からの電流容量積算値ΣＡ（ｈ）を加算して最終バッテリ容量ＳＯＣを推定し、ＳＯＣ出力部１６に出力する。
【００２２】
つまり、次のような補正演算を行うのである。
【００２３】
【数１】

Figure 0003669202
ここで、Ｋはバッテリ容量推定値であり、次の電流容量ＡｈをＳＯＣの単位である％に合わせるための換算値である。すなわち、
【数２】
Figure 0003669202
で求める。例えば、１Ａｈは３３％であり、３Ａｈであれば１００％であるので、Ｋ＝１Ａｈ／３３％を用いる。
【００２４】
これにより、ＳＯＣ出力部１６は最終バッテリ容量として、開放電圧ＯＣＶから正確に換算できる電流範囲を超えたバッテリの使用状態においても電流容量によりバッテリ容量を補正してほぼ正確にバッテリ容量ＳＯＣを出力することができる。
【００２５】
制御演算部１１は、バッテリ電流Ｉｂが所定範囲内に復帰したときには電流容量演算部１４とＳＯＣ補正部１５に対してリセット指令を与え、電流容量演算部１４の電流容量積算演算をリセットさせ、またＳＯＣ補正部１５の電流容量積算値ΣＡ（ｈ）による補正演算を中止させ、ＳＯＣ換算部１３が出力するＳＯＣ換算値を最終ＳＯＣとしてＳＯＣ出力部１６に出力するようにする。
【００２６】
これにより、バッテリ開放電圧ＯＣＶからバッテリ容量ＳＯＣを正確に換算できる範囲では常にその換算値を用いてバッテリ容量ＳＯＣを求め、換算が正確にできる範囲を逸脱する使用状態では電流容量積算値によってバッテリ容量を補正し、常にほぼ正確なバッテリ容量ＳＯＣを演算出力できる。
【００２７】
なお、電流容量演算部１４は、バッテリ１の特性に依存するが、リチウムイオンバッテリの場合、例えば、バッテリ電流Ｉｂの使用状態が、１秒当りに６０Ａ以上も急激に変化するようなものであれば、バッテリ電圧Ｖｂはバッテリ電流Ｉｂの放電に見合う電圧値まで低下するのに時間遅れがあり、バッテリ電流Ｉｂとバッテリ電圧Ｖｂによってバッテリ開放電圧ＯＣＶを求めても正確な値を得ることができなくなる。
【００２８】
そこで、制御演算部１１にこのバッテリ電流Ｉｂの時間変化をも監視させ、例えば、２０Ｃ（１時間放電容量１Ｃの２０倍の速さでの放電）を超える放電である場合にも、ＯＣＶからＳＯＣを換算して最終バッテリ容量を求めることを中止し、電流容量演算部１４に電流容量積算演算を開始させ、直前のＳＯＣに対して補正演算を行い、最終ＳＯＣを出力する構成にすることができる。
【図面の簡単な説明】
【図１】本発明の１つの実施の形態の構成のブロック図。
【図２】上記の実施の形態におけるコントローラの詳しい構成を示すブロック図。
【図３】上記の実施の形態によるバッテリ容量ＳＯＣ演算の場合分けを示す説明図。
【図４】一般的なリチウムイオンバッテリの開放電圧ＯＣＶとバッテリ電流との関係を示すグラフ。
【図５】一般的なリチウムイオンバッテリの開放電圧ＯＣＶ−バッテリ容量ＳＯＣの関係を示すグラフ。
【図６】一般的なリチウムイオンバッテリの内部抵抗特性の変化を示すグラフ。
【符号の説明】
１ バッテリ
２ 負荷
３ 電流計
４ 電圧計
５ エンジン
６ コントローラ
１１ 演算制御部
１２ ＯＣＶ演算部
１３ ＳＯＣ換算部
１４ 電流容量演算部
１５ ＳＯＣ補正部
１６ ＳＯＣ出力部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery state monitoring device that monitors a charge / discharge state of an in-vehicle battery.
[0002]
[Prior art]
Conventionally, in a battery state monitoring device that monitors a charge / discharge state of a lithium ion battery mounted on a parallel hybrid electric vehicle (PHEV) in particular, an open circuit voltage OCV is estimated from the charge / discharge voltage and the charge / discharge current of the battery, The battery capacity SOC is estimated from this open circuit voltage, and this battery capacity estimated value is used for various controls.
[0003]
That is, as shown in FIG. 4, the open circuit voltage OCV of the battery is an internal resistance that can be obtained from the detected battery voltage Vb and battery current Ib, and two battery voltages Vb1 and Vb2 and battery currents Ib1 and Ib2. It calculates | requires as follows from Rn.
[0004]
OCV = Vb + Ib · Rn
However, the internal resistance Rn is obtained by Rn = (Vb2-Vb1) / (Ib2-Ib1).
[0005]
In the case of a lithium ion battery, the open circuit voltage OCV and the battery capacity SOC have a correlation as shown in FIG. 5, and the SOV is uniquely determined from the OCV.
[0006]
[Problems to be solved by the invention]
However, such a conventional battery state monitoring device has the following problems. In the lithium ion battery, as shown in FIG. 6, the internal resistance changes depending on the discharge rate, and the behavior of the change is almost linear in each discharge cycle while the discharge rate is small. When the discharge rate is reached, the internal resistance cannot be strictly defined. Therefore, there is a problem that the open circuit voltage OCV cannot be accurately obtained, and as a result, the battery capacity SOC cannot be accurately estimated.
[0007]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a battery state monitoring device capable of accurately estimating the battery capacity even when the discharge rate is large.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a battery monitoring apparatus for monitoring a state of a lithium ion battery, wherein a current detection means for detecting a battery current, a voltage detection means for detecting a battery voltage, and the current detection means Based on the detected battery current and the battery voltage detected by the voltage detection means, internal resistance calculation means for calculating the internal resistance of the battery, and using the battery current, the battery voltage, and the internal resistance to open the battery An open-circuit voltage calculating means for calculating a voltage; a battery capacity estimating means for estimating a battery capacity from the battery open voltage calculated by the open-circuit voltage calculating means; and a current capacity calculating means for integrating the current capacity using the battery current; When the battery current is within a predetermined range, the battery capacity estimating means estimates If the battery current is out of the predetermined range, the battery capacity estimated by the battery capacity estimation means immediately before deviating from the predetermined range is outside the predetermined range. And a battery capacity correcting means for adding the current capacity accumulated by the current capacity calculating means and outputting the result as the final battery capacity after the point of departure.
[0009]
A battery state monitoring device according to a second aspect of the present invention is the battery state monitoring device according to the first aspect, wherein the battery capacity correction means sets the predetermined range of the battery current in a range in which the current dependent change rate of the internal resistance is substantially constant.
[0010]
In the battery state monitoring device according to the first and second aspects of the present invention, the internal resistance of the battery is calculated based on the battery current detected by the current detection means and the battery voltage detected by the voltage detection means by the internal resistance calculation means, and then opened. The voltage calculation means calculates the battery open voltage using the battery current detected by the battery current detection means, the battery voltage detected by the battery voltage detection means, and the internal resistance, and further the battery capacity estimation means uses the open voltage calculation means. The battery capacity is estimated from the calculated battery open voltage. On the other hand, the current capacity calculation means integrates the current capacity using the battery current detected by the current detection means.
[0011]
The battery capacity correcting means sets the battery capacity estimated by the battery capacity estimating means as the final battery capacity when the battery current is within the predetermined range, and out of the predetermined range when the battery current is outside the predetermined range. Immediately before the departure, the battery capacity estimated by the battery capacity estimation means is added with the current capacity accumulated by the current capacity calculation means after the time of departure from the predetermined range, and output as the final battery capacity.
[0012]
As a result, when the battery current is within a predetermined range where the rate of change of the internal resistance of the battery is substantially constant, the battery capacity is accurately estimated from the battery open voltage and output as the final battery capacity. When the rate of change of the internal resistance of the battery deviates from a predetermined range, the integration of the current capacity after deviating from the predetermined range with respect to the battery capacity estimated from the battery open voltage immediately before deviating from the range. Correction for adding values can be performed and output as the final battery capacity, and accurate battery capacity monitoring can be performed even in a usage state where the battery current changes drastically.
[0013]
According to a third aspect of the present invention, there is provided the battery state monitoring device according to the first or second aspect, wherein the battery capacity correcting means determines the battery capacity estimating means when the battery current returns to the predetermined range. The battery capacity is reset to the estimated battery capacity, and the battery capacity can be accurately monitored even after a use state in which the discharge rate changes drastically.
[0014]
【The invention's effect】
According to the first and second aspects of the invention, in the battery monitoring device for monitoring the state of the lithium ion battery, when the battery current is within a predetermined range in which the rate of change of the internal resistance of the battery is substantially constant, the battery open voltage The battery capacity is accurately estimated and output as the final battery capacity. If the battery current deviates from a predetermined range where the rate of change of the internal resistance of the battery is almost constant, the battery is released immediately before deviating from that range. The battery capacity estimated from the voltage can be corrected by adding the integrated value of the current capacity after deviating from the specified range and output as the final battery capacity. Battery capacity monitoring is possible.
[0015]
According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, when the battery current returns to a predetermined range, the battery capacity is reset to the battery capacity estimated by the battery capacity estimating means as the final battery capacity. As a result, the battery capacity can be accurately monitored even after a use state in which the discharge rate changes drastically.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of one embodiment of the present invention. The battery state monitoring device of this embodiment receives an ammeter 3 for detecting a battery current Ib flowing from the battery 1 to the load 2, a voltmeter 4 for detecting the battery voltage Vb, and the battery current Ib and the battery voltage Vb. A controller 6 that calculates the battery capacity SOC and controls the engine 5 and other devices, and a generator 7 that generates electric power by driving the engine 5 and supplies a charging current to the battery 1 are provided. In the case of a parallel hybrid electric vehicle PHEV, the rotational output of the engine 5 is directly used to drive the vehicle.
[0017]
FIG. 2 shows the configuration of the battery capacity calculation circuit in the controller 6. The battery capacity calculation circuit includes a calculation control unit 11 that performs overall control, an OCV calculation unit 12 that obtains an open circuit voltage OCV from the battery current Ib and the battery voltage Vb, and OCV-SOC correlation characteristic data. An SOC conversion unit 13 that estimates and outputs the battery capacity SOC corresponding to the output open circuit voltage OCV, a current capacity calculation unit 14 that calculates the current capacity ΣA (h) by integrating the battery current Ib over time, and a calculation control unit 11, the SOC correction unit 15 that corrects the estimated battery capacity SOC from the SOC conversion unit 13 using the current capacity ΣA (h) from the current capacity calculation unit 14 to obtain the final battery capacity SOC, The SOC output unit 16 outputs the final battery capacity SOC.
[0018]
Next, the operation of the battery state monitoring apparatus having the above configuration will be described. In the case of this embodiment, as shown in FIG. 3, the area where the battery capacity SOC converted from the open circuit voltage OCV is directly used as the final battery capacity SOC is set in the range of -10A to 10A. . Note that, as described in the conventional example, this region is a range in which the rate of change of the internal resistance due to the change in the discharge rate of the lithium ion battery is substantially constant, about −30 A to +30 A in the graph shown in FIG. Can be set within range. The OCV calculation unit 12 takes in the battery current Ib (plus (+) during discharge and minus (-) during charge) detected by the battery ammeter 3 and the battery voltage Vb detected by the battery voltmeter 4 at a predetermined cycle. The detected values of the two valid battery currents and battery voltages that have been captured so far (the detected values used here are the two detected values that can effectively calculate the internal resistance) Ib1, Ib2; Vb1 , Vb2, the internal resistance Rn is obtained by the above-described equation, and the open-circuit voltage OCV is obtained from the newly taken battery current Ib and battery voltage Vb.
OCV = Vb + Ib · Rn
And output to the SOC conversion unit 13.
[0019]
The SOC conversion unit 13 refers to the built-in open circuit voltage OCV-battery capacity SOC correlation characteristic data shown in FIG. 5 and obtains and outputs the battery capacity SOC corresponding to the input battery open voltage OCV.
[0020]
The arithmetic control unit 11 monitors the battery current Ib. When the battery current Ib deviates from the predetermined current range described above, the arithmetic control unit 11 gives an integration command to the current capacity calculation unit 14 and gives a correction command to the SOC correction unit 15. give.
[0021]
Then, the current capacity calculator 14 performs time integration of the input battery current Ib to obtain a current capacity integrated value ΣA (h) and outputs it to the SOC corrector 15. When there is no correction command from the control calculation unit 11, the SOC correction unit 15 outputs the battery capacity SOC from the SOC conversion unit 13 to the SOC output unit 16 as the final battery capacity and receives the correction command from the control calculation unit 11. The current capacity integrated value ΣA (h) from the current capacity calculation unit 14 is added to the battery capacity conversion value SOC from the SOC conversion unit 13 to estimate the final battery capacity SOC and output it to the SOC output unit 16. .
[0022]
That is, the following correction calculation is performed.
[0023]
[Expression 1]
Figure 0003669202
Here, K is an estimated battery capacity value, which is a conversion value for adjusting the next current capacity Ah to% which is a unit of SOC. That is,
[Expression 2]
Figure 0003669202
Ask for. For example, since 1Ah is 33% and 3Ah is 100%, K = 1Ah / 33% is used.
[0024]
As a result, the SOC output unit 16 corrects the battery capacity with the current capacity and outputs the battery capacity SOC almost accurately even when the battery is in use, exceeding the current range that can be accurately converted from the open circuit voltage OCV, as the final battery capacity. be able to.
[0025]
The control calculation unit 11 gives a reset command to the current capacity calculation unit 14 and the SOC correction unit 15 when the battery current Ib returns within a predetermined range, and resets the current capacity integration calculation of the current capacity calculation unit 14, The correction calculation by the current capacity integrated value ΣA (h) of the SOC correction unit 15 is stopped, and the SOC conversion value output from the SOC conversion unit 13 is output to the SOC output unit 16 as the final SOC.
[0026]
Thus, the battery capacity SOC is always obtained using the converted value in the range where the battery capacity SOC can be accurately converted from the battery open voltage OCV, and the battery capacity is calculated based on the current capacity integrated value in the usage state deviating from the range where the conversion can be accurately performed. Can be calculated and the battery capacity SOC can always be calculated and output.
[0027]
The current capacity calculation unit 14 depends on the characteristics of the battery 1, but in the case of a lithium ion battery, for example, the usage state of the battery current Ib may change abruptly by 60 A or more per second. For example, the battery voltage Vb has a time delay in dropping to a voltage value commensurate with the discharge of the battery current Ib, and an accurate value cannot be obtained even when the battery open voltage OCV is obtained from the battery current Ib and the battery voltage Vb. .
[0028]
Therefore, the control calculation unit 11 also monitors the time change of the battery current Ib. For example, even when the discharge exceeds 20C (discharge at a speed 20 times the discharge capacity 1C for 1 hour), the OCV to the SOC The calculation of the final battery capacity can be stopped by converting the value, the current capacity calculation unit 14 can start the current capacity integration calculation, the correction calculation is performed on the immediately preceding SOC, and the final SOC can be output. .
[Brief description of the drawings]
FIG. 1 is a block diagram of a configuration of one embodiment of the present invention.
FIG. 2 is a block diagram showing a detailed configuration of a controller in the embodiment.
FIG. 3 is an explanatory diagram showing a case classification of battery capacity SOC calculation according to the above embodiment.
FIG. 4 is a graph showing a relationship between an open circuit voltage OCV and a battery current of a general lithium ion battery.
FIG. 5 is a graph showing a relationship between an open circuit voltage OCV and a battery capacity SOC of a general lithium ion battery.
FIG. 6 is a graph showing a change in internal resistance characteristics of a general lithium ion battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery 2 Load 3 Ammeter 4 Voltmeter 5 Engine 6 Controller 11 Calculation control part 12 OCV calculation part 13 SOC conversion part 14 Current capacity calculation part 15 SOC correction part 16 SOC output part

Claims (3)

リチウムイオンバッテリの状態を監視するバッテリ監視装置において、
バッテリ電流を検出する電流検出手段と、
バッテリ電圧を検出する電圧検出手段と、
前記電流検出手段の検出した前記バッテリ電流と前記電圧検出手段の検出した前記バッテリ電圧とに基づいて、バッテリの内部抵抗を演算する内部抵抗演算手段と、
前記バッテリ電流、前記バッテリ電圧及び前記内部抵抗を用いてバッテリ開放電圧を演算する開放電圧演算手段と、
前記開放電圧演算手段の算出した前記バッテリ開放電圧からバッテリ容量を推定するバッテリ容量推定手段と、
前記バッテリ電流を用いて電流容量を積算する電流容量演算手段と、
前記バッテリ電流が所定範囲内にある場合には前記バッテリ容量推定手段の推定する前記バッテリ容量を最終バッテリ容量とし、前記バッテリ電流が前記所定範囲外である場合には当該所定範囲外に逸脱する直前に前記バッテリ容量推定手段の推定したバッテリ容量に対して、当該所定範囲外に逸脱した時点以降に前記電流容量演算手段の積算した電流容量を加算して最終バッテリ容量として出力するバッテリ容量補正手段とを備えて成るバッテリ状態監視装置。 In a battery monitoring device that monitors the state of a lithium ion battery,
Current detection means for detecting battery current;
Voltage detection means for detecting the battery voltage;
Internal resistance calculating means for calculating the internal resistance of the battery based on the battery current detected by the current detecting means and the battery voltage detected by the voltage detecting means;
An open voltage calculation means for calculating a battery open voltage using the battery current, the battery voltage and the internal resistance;
Battery capacity estimating means for estimating a battery capacity from the battery open voltage calculated by the open voltage calculating means;
Current capacity calculating means for integrating current capacity using the battery current;
When the battery current is within the predetermined range, the battery capacity estimated by the battery capacity estimating means is set as the final battery capacity, and when the battery current is outside the predetermined range, immediately before deviating from the predetermined range. Battery capacity correcting means for adding the current capacity accumulated by the current capacity calculating means after the time deviating from the predetermined range to the battery capacity estimated by the battery capacity estimating means and outputting as a final battery capacity A battery state monitoring device comprising: 前記バッテリ容量補正手段は、前記内部抵抗の電流依存変化率がほぼ一定の範囲を前記バッテリ電流の所定範囲としたことを特徴とする請求項１に記載のバッテリ状態監視装置。2. The battery state monitoring device according to claim 1, wherein the battery capacity correction unit sets a predetermined range of the battery current as a range in which a current dependent change rate of the internal resistance is substantially constant. 前記バッテリ容量補正手段は、前記バッテリ電流が前記所定範囲内に復帰したときに、前記最終バッテリ容量を前記バッテリ容量推定手段の推定する前記バッテリ容量にリセットすることを特徴とする請求項１または２に記載のバッテリ状態監視装置。3. The battery capacity correction unit, when the battery current returns to the predetermined range, resets the final battery capacity to the battery capacity estimated by the battery capacity estimation unit. The battery state monitoring device described in 1.
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