JP2004085269A - Method and apparatus for measuring battery charge state - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring a battery charging state which can accurately measure the charging state of the battery, by making bringing about large accumulated errors difficult, by continuously accumulating charging and discharging currents for a long period. <P>SOLUTION: The method for measuring the battery charging state includes the steps of adding and subtracting present charging state of the battery of charging current and discharging current periodically measured by a current measuring means 15 by means of an accumulation type charging state measuring means 23a-1, and measuring the charging state of the battery. The method further includes the steps of estimating an open circuit voltage by an open circuit voltage estimating means 23a-3, based on a transition of a terminal voltage measured by a voltage-measuring means 23a-2 after the charging or discharging is substantially finished, and calculating to obtain the charging state of the battery by an arithmetic meas 23a-4, based on the estimated open circuit voltage. The method also includes the steps of updating the present charging state by a charging state updating means 23a-5 by using the charging state obtained by the means 23a-4, and setting the present charging state. <P>COPYRIGHT: (C)2004,JPO

Description

【００８０】
充放電終了後の開回路電圧を推定する際に、一般に２分木探索法と呼ばれる方法で想定開回路電を更新する。最初に、想定開回路電圧は、図８に示すように、例えば上限想定開回路電圧Ｖ（Ｔｂ）と下限想定開回路電圧０と、その中間想定開回路電圧Ｖ（Ｔｂ）／２の場合について累乗近似を行う。
【００８１】
それぞれの近似から求められるβ（Ｖ（Ｔｂ））、β（０）、β（Ｖ（Ｔｂ）／２）を相互に比較し、中間想定開回路電圧のβが−０．５に等しいか、等しくない場合には、−０．５に対して大きいか、小さいかの比較を行う。中間想定開回路電圧のβが−０．５でない場合、−０．５となるデータが含まれている範囲、表１の例では、中間想定開回路電圧と上限想定開回路電圧との間の範囲について２分割した想定開回路電圧（Ｖ（Ｔｂ）＋Ｖ（Ｔｂ）／２）／２のβを算出し、β＝−０．５となるまで比較演算を繰り返す。その具体的な例を表１に示している。表１の例では、探索回数１以外でも、下限、中間及び上限のそれぞれのべき数βを演算して求めているが、２回目以降の探索では、べき数βの演算は中間だけでよい。
【００８２】
なお、想定開回路電圧を更新して繰り返し実行しても、べき数が−０．５とならいことがあるときには、下限想定開回路電圧と上限想定開回路電圧の小数点以下３桁目の数値が１程度の差しかなくなったところで、べき数が略−０．５になったと判断し、このときの想定開回路電圧を開回路電圧と推定し、必要以上に累乗近似式を決定する処理を繰り返すことをなくすることができる。
【００８３】
最初の上限想定開回路電圧をＶ（Ｔｂ）とするのは、開回路電圧がＶ（Ｔｂ）よりも高くなることがないからである。下限想定開回路電圧については、放電完了（容量０％）時の開回路電圧でもよいが、過放電が行われている場合には、放電完了（容量０％）時の開回路電圧を下まわる可能性があるので初期値を０Ｖにしている。
【００８４】
次に、本実施形態の開回路電圧推定動作（作用）について説明する。まず、ハイブリッド車両のモータジェネレータ５以外の電装品（負荷）が作動したり、モータジェネレータ５がモータとして機能するように作動しているときはバッテリ１３が放電を行っているが、モータジェネレータ５がジェネレータとして機能するように作動しているときにはバッテリ１３に充電が行われている。このバッテリの充放電は電流センサ１５の出力を取り込むことによって検出でき、充放電の終了も電流センサ１５の出力が所定値以下になっていることよって検出できる。
【００８５】
電流センサ１５の出力により、充放電の終了が検出されると、それから一定時間Ｔａが経過した時点から時間Ｔｂまでの間、電圧センサ１７の出力を取り込むことによって、バッテリの端子電圧を端子電圧として周期的に測定し、これらの電圧値と充放電の終了後からの経過時間をＲＡＭ２３ｂのデータエリアに格納、記憶して収集する。収集された端子電圧Ｖ（ｔ）から想定開回路電圧Ｅを減算し、減算して求めた値から最小二乗法を適用して累乗近似式を決定する。決定した累積近似式α・ｔ^βのべき数βが−０．５となっているかどうかを判断し、べき数βが−０．５になっていないときには、想定開回路電圧Ｅを新しいものに更新して再度同様の処理を行って累乗近似式α・ｔ^βを決定する。以上の動作をべき数βが−０．５になるか、又は、略−０．５になるまで繰り返し行い、何れかが成立したとき、そのときの想定開回路電圧を開回路電圧と推定するようにする。なお、略−０．５になったことの確認は、累乗近似式の決定回数が所定回数となるか、又は、想定開回路電圧範囲が予め定めた範囲以下になったことで行うことができる。
【００８６】
上述したように推定した開回路電圧は、累乗近似式α・ｔ^βの漸近線となっているので、時間Ｔａ及びＴｂが異なっても、移動するものでないので、バッテリの特性が多少異なっていてもそのまま適用することができる。しかも、充放電の終了から時間Ｔａ〜Ｔｂの間、充放電電流が流れなければ、その都度、開回路電圧を推定することが可能になり、開回路電圧を推定できる頻度を多くすることができる。
【００８７】
そして、本発明は、モータジェネレータが回生電力をバッテリに充電するようになっているハイブリットカーなどの車両において、バッテリの充電状態を適切に知り、効率的にバッテリを利用して燃費向上を図るために有効に適用できる。
【００８８】
なお、本願明細書中においては、分極などの影響を受けた端子電圧を端子電圧とし、平衡状態のときの端子電圧を開回路電圧としている。
【００８９】
また、本実施形態では、ハイブリッド車両においてバッテリの開回路電圧を推定する場合について説明したが、本発明は、一般的な１４Ｖ車両や１４Ｖと４２Ｖ等の多電源車、電気自動車、通常のガソリン自動車等、種々の車両に搭載されたバッテリの開回路電圧の推定に適用可能であることは、言うまでもない。
【００９０】
ところで、一般的に、充放電直後のバッテリの端子電圧の変化には、内部抵抗、活性化分極、ガス発生を伴う過電圧など、電解液の拡散に関係の無い電圧変化分を含んでいて、誤差要因となるので、何れの場合にも電解液の拡散に関係の無い電圧変化分を含む期間の端子電圧については、端子電圧を測定して収集しても意味がない。
【００９１】
また、一般的に、時間が経過するにつれ電圧変化が小さくなることにより、測定の分解能によっては推定精度が低下する恐れがあので、何れの場合にも分解能が低すぎて推定精度のでない期間の端子電圧については、それ以上の端子電圧の測定に意味がなくなる。
【００９２】
そこで、電解液の拡散に関係の無い電圧変化分を含んでいて、誤差要因となる期間の測定を除くため、端子電圧の測定開始点を、充放電の終了から所定時間Ｔａ経過した後からとして定めることもできるが、バッテリの状況によって、誤差要因の解消する時点が異なり、一律に定めると、バッテリの状況によっては、誤差要因のない端子電圧を測定して使用できなかったり、あるいは、誤差要因のある端子電圧を測定して使用してしまったりする。
【００９３】
また、測定の分解能によって推定精度が低下する期間に入ってからの測定を除くため、端子電圧の測定終了点を、充放電の終了から所定時間Ｔｂ経過したところまでとして定めることもできるが、分解能が問題になるのは、累乗近似を行うために使用する端子電圧相互間の誤差要因の大小である。すなわち、累乗近似に使用する他の端子電圧に含まれる誤差要因との大小が問題になるのであって、一律に決めると、バッテリの状況によっては、問題にならない分解能の端子電圧を測定して使用できなかったり、あるいは、問題になる分解能の端子電圧を測定して使用してしまったりする。
【００９４】
勿論、バッテリがどのような状況になっても、誤差要因の入らない期間を設定することも考えられるが、このような考えのもとで、測定期間を予め定めようとすると、測定期間が存在しなくなったり、定めた期間が必ずしも適切なものでなかったりする。
【００９５】
よって、バッテリの状況に左右されることなく、バッテリの開回路電圧を正確に推定できるようにする考え方を以下説明する。
【００９６】
先ず、端子電圧の測定開始点を定める充放電の終了から所定時間Ｔａとして、誤差要因の解消が早い場合の端子電圧を測定できる早めの例えば５分を、端子電圧の測定終了点を定める充放電の終了から所定時間Ｔｂとして、多少分解能が低下する場合の端子電圧も測定できる遅めの例えば８０分をそれぞれ設定し、充放電の終了から所定時間Ｔａ乃至Ｔｂの測定期間の間、例えば１０秒の所定の周期で端子電圧を測定し、この測定した端子電圧をメモリに記憶させることで収集する。
【００９７】
なお、充放電を停止した後、例えば５分の予め定めた時間Ｔａを経過してから、端子電圧のサンプリングを開始するのは、充放電直後の電圧変化には、内部抵抗、活性化分極、ガス発生に伴う過電圧など、電解液の拡散に関係ない電圧変化分が含まれており、この変化分をサンプリングすると誤差要因となるので、累乗近似式を求めるためのデータに含ませないためである。
【００９８】
また、サンプリングを例えば８０分の予め定めた時間Ｔｂまでとしているのは、便宜上だけのためばかりでなく、時間経過について電圧変化分が小さくなることにより、測定の分解能によっては開回路電圧の推定精度を低下する虞があるほか、車両の暗電流による電圧降下の影響が時間経過により大きくなるからである。
【００９９】
次に、充放電の終了から所定時間Ｔａ乃至Ｔｂの測定期間の間に測定して収集した端子電圧に対して複数の期間を予め定めるため、所定時間Ｔａ（５分）に対応して、５分を最短点Ｔａ１とし、これに１０分に例えば１０分の一定時間を加算してＴａ２（１５分）、Ｔａ３（２５分）、Ｔａ４（３５分）、Ｔａ５（４５分）を定めるとともに、所定時間Ｔｂ（８０分）に対応して、８０分を最長点Ｔｂ４とし、これから例えば２０分の一定時間を減算してＴｂ３（６０分）、Ｔｂ２（４０分）、Ｔｂ１（２０分）を定める。そして、Ｔａ１（５分）、Ｔａ２（１５分）、Ｔａ３（２５分）、Ｔａ４（３５分）、Ｔａ５（４５分）を各期間の開始点の一つとして、Ｔｂ４（８０分）、Ｔｂ３（６０分）、Ｔｂ２（４０分）、Ｔｂ１（２０分）を各期間の終了点の一つとしてそれぞれ使用し、複数の開始点の一つと複数の終了点の一つとの組み合わせによって、収集した端子電圧に対して複数の期間を予め定めている。
【０１００】
すなわち、充放電の終了から所定時間Ｔａ乃至Ｔｂの測定期間の間に測定して収集した端子電圧に対して、Ｔａ１（５分）−［Ｔｂ４（８０分）、Ｔａ２（１５分）−［Ｔｂ４（８０分）、Ｔｂ３（６０分）、Ｔｂ２（４０分）又はＴｂ１（２０分）］、Ｔａ３（２５分）−［Ｔｂ４（８０分）、Ｔｂ３（６０分）又はＴｂ２（４０分）］、Ｔａ４（３５分）−［Ｔｂ４（８０分）、Ｔｂ３（６０分）又はＴｂ２（４０分）］、Ｔａ５（４５分）−［Ｔｂ４（８０分）又はＴｂ３（６０分］という異なる１６個の期間が網羅的に漏れなく設定できるようになっている。
【０１０１】
なお、開始点の最短点と終了点の最長点が、端子電圧を測定して収集する期間の開始と終了の点に対応させているので、端子電圧を測定して収集する期間を別途設けることが必要ない。また、複数の開始点の間隔を複数の終了点の間隔よりも小さくしているので、内部抵抗、活性化分極、ガス発生を伴う過電圧など、電解液の拡散に関係の無い電圧変化分を含んでいて、誤差要因となり易い充電又は放電直後に近い部分について、より細かく期間を設定することが可能になっている。
【０１０２】
そこで、バッテリの充放電が終了後、例えば５分の予め定めた時間Ｔａを経過してから、例えば８０分の予め定めた時間Ｔｂまでの間のバッテリの端子電圧を例えば１０秒の周期で測定して収集する。この測定し収集した端子電圧に対して予め定めた複数の期間の各期間内の端子電圧に基づいて近似された、べき数が−０．５となるか、又は、略−０．５となる累乗近似式が漸近する電圧値を各期間の想定開回路電圧として求める。
【０１０３】
特に、バッテリの充電が終了後の場合には、図５に示すように、各期間の収集した端子電圧より、想定した開回路電圧Ｅを減算し各期間の累乗近似式α・ｔ^βを算出する。
【０１０４】
これに対して、バッテリの放電が終了した場合、バッテリの開放状態での端子電圧は、濃度分極によって下降していた分が時間とともに解消して徐々に増加し、例えば２４時間後のバッテリの平衡状態における端子電圧である開回路電圧ＥＯ　に漸近する。このように、放電の場合、想定開回路電圧Ｅの方が累乗近似式α・ｔ^βより常に大きいので、各期間の測定した端子電圧より、想定した開回路電圧Ｅを減算した値が負となるので、端子電圧より想定開回路電圧Ｅを減算した値の絶対値を利用して各期間の累乗近似式α・ｔ^βを算出する。
【０１０５】
一般的に、充電又は放電が終了した後、各期間の測定した端子電圧から、想定した開回路電圧を減算した値により、べき数が負である予め定めた累乗近似式を決定し、この決定した累乗近似式のべき数が−０．５となるまで、累乗近似式の決定を想定開回路電圧を更新して繰り返し実行し、べき数が−０．５となったときの想定開回路電圧を開回路電圧と推定すればよい。
【０１０６】
なお、想定開回路電圧を予め定めた回数更新して繰り返し実行しても、べき数が−０．５とならないことがあるときには、予め定めた回数が実行されたことによってべき数が略−０．５になったと判断し、このときの想定開回路電圧を開回路電圧と推定し、必要以上に累乗近似式を決定する処理を繰り返すことをなくすことができる。
【０１０７】
今、バッテリを０から１００％まで充電した場合について、上述したように充電の終了から所定時間Ｔａ１から所定時間Ｔｂ４まで１０秒の一定の周期で測定した端子電圧に基づき、上述したようにして各期間の測定した端子電圧を累乗近似して想定開回路電圧を求め、その結果を表にして示すと、表２のようになる。
【０１０８】
【表２】

【０１０９】
表２には、隣接する期間の想定開回路電圧との差も一緒に示されている。例えば、期間Ｔａ２−Ｔｂ３の想定開回路電圧は１２．７７６５Ｖであるが、この期間の左の期間Ｔａ２−Ｔｂ２の想定開回路電圧１２．７６００Ｖ、右の期間Ｔａ２−Ｔｂ４の想定開回路電圧１２．７９００Ｖ、上の期間Ｔａ１−Ｔｂ３の想定開回路電圧１２．７７５２Ｖ、下の期間Ｔａ３−Ｔｂ３の想定開回路電圧１２．７８８５Ｖとの差は、０．０１６５、−０．０１３４、０．００１３、−０．０１１３となることが示されている。なお、表１中、上下左右に隣接する期間のない期間については、隣接する期間の想定開回路電圧との差を見ることができないので、ブランクにしてある。
【０１１０】
上述したようにして求めた各期間について求めた隣接する期間の想定開回路電圧との差を相互に比較すると、期間Ｔａ１−Ｔｂ３（５分−６０分）の間に測定した端子電圧を使用して決定した累乗近似式が漸近する漸斤値から求まる想定開回路電圧が隣接する期間との差が最も小さくなっていることが分かる。そして、この期間Ｔａ１−Ｔｂ３（５分−６０分）の測定した端子電圧に基づく想定開回路電圧は、充電後のバッテリが平衡する２４時間経過した時点で測定した端子電圧、すなわち、平衡状態の開回路電圧の実測値１２．７７４２５Ｖとの差が約１ｍＶと非常に小さく、他の期間にこれよりも小さな違いの想定開回路電圧が存在しないことも確認された。
【０１１１】
下表３は、バッテリを５０％まで充電し、表２の場合とは状況の異なるバッテリについて示したものであるが、この表２からは、表１の場合と異なり、期間Ｔａ４−Ｔｂ３（３５分−６０分）の間に測定した端子電圧を使用して決定した累乗近似式が漸近する漸斤値から求まる想定開回路電圧１２．３０４０Ｖが、平衡状態の開回路電圧の実測値１２．２９６９Ｖとの差が約７ｍＶとなり、期間Ｔａ１−Ｔｂ３（５分−６０分）の約２７ｍＶよりも小さくなっていることが分かる。
【０１１２】
【表３】

【０１１３】
要するに、予め定めた複数の期間において求めた想定開回路電圧のうち、隣接する期間の想定開回路電圧の差が最も小さくなる期間、具体的には、隣接する期間の想定開回路電圧との差の絶対値の総和を隣接する期間の数で除した値が最小となる期間の想定開回路電圧をもってバッテリの開回路電圧とすることで、開回路電圧を精度良く推定することができることが分かる。
【０１１４】
次に、前記ＲＯＭ２３ｃに格納された制御プログラムに従いＣＰＵ２３ａが行うバッテリの開回路電圧推定処理を、図９及び図１０を参照して説明する。
【０１１５】
バッテリ１３からの給電を受けてマイコン２３は起動しているものとし、マイコン２３は、例えば電流センサ１５の出力をサンプリングして得た電流値に基づいて、電流値が０になっているかどうかにより、充電又は放電が終了したかどうかを判定する。この判定の結果、充電又は放電の終了が検出されたときに、図９のフローチャートに示す開回路電圧推定処理を開始する。この開回路電圧推定処理においては、まず充電又は放電の終了から例えば５分の予め定めた時間Ｔａ１が経過したかどうかを判断する（ステップＳ１１）。
【０１１６】
時間が経過していないときには、時間が経過するのを待ち、時間が経過したときには（ステップＳ１１のＹ）、次に例えば１０秒の一定時間毎に電圧センサ１７の出力によりバッテリの端子電圧を端子電圧として測定してこれをＲＡＭ２３ｂのデータエリア（端子電圧収集手段に相当する）に格納、記憶することで収集する（ステップＳ１２）。そして、このサンプリングを、充電又は放電の終了から例えば８０分の予め定めた時間Ｔｂ４が経過するまで継続する（ステップＳ１３のＮ）。
【０１１７】
時間Ｔｂ４が経過すると（ステップＳ１３のＹ）、次に、充電又は放電が終了した後の時間５分から８０分によって定められる測定期間の中に予め定めた複数の開始点５分、１５分、２５分及び３５分の一つを選択してＴａを設定する（ステップＳ１４）とともに、予め定めた複数の終了点２０分、４０分、６０分及び８０分の一つを選択してＴｂを設定し、この選択設定された開始点と終了点とを組み合わせて複数の期間の一つが定められる（ステップＳ１４及びステップＳ１５）。期間が定められたら、その期間の測定した端子電圧を使用して当該期間の想定開回路電圧を算出する処理を行う（ステップＳ１６）この想定開回路電圧算出処理は、全ての期間について終了するまで継続して行われる（ステップＳ１７のＮ）。
【０１１８】
全ての期間の想定開回路電圧が算出されたら、各期間の想定開回路電圧について、隣接する期間の想定開回路電圧との差を算出してこれをＲＡＭ２３ｂのデータエリア（記憶手段に相当する）に格納する（ステップＳ１８）。そして、この格納した隣接する期間の想定開回路電圧との差が最も小さい期間を選出し、この選出した期間の想定開回路電圧をもってバッテリの開回路電圧と推定する（ステップＳ１９）。隣接する期間の想定開回路電圧の差が最も小さくなる期間の選出は、具体的には、隣接する期間の想定開回路電圧との差の絶対値の総和を隣接する期間の数で除した値が最小となる期間を選出することで行われる。
【０１１９】
また、上述した図９のフローチャート中のステップＳ１６における各期間の想定開回路電圧算出処理は、具体的には、図１０のフローチャートに示すようにして行われる。
【０１２０】
先ず、各期間の測定した端子電圧Ｖ（ｔ）と、想定した開回路電圧Ｅとの差値、即ち、充電後の場合は、測定した端子電圧Ｖ（ｔ）から想定した開回路電圧Ｅを減算した値、放電後の場合は、測定した端子電圧Ｖ（ｔ）から想定した開回路電圧Ｅを減算した値の絶対値、を求め（ステップＳ１６ａ）、求めた値ｆ（ｔ）について累乗近似処理を行ってべき数が負である予め定めた累乗近似式を決定する（ステップＳ１６ｂ）。
【０１２１】
累乗近似式が決定したら、次に決定した累乗近似式のべき数βが−０．５に等しいかどうかを判断し（ステップＳ１６ｃ）、この判断の結果、べき数βが−０．５となっていないときには（ステップＳ１６ｃのＮ）、想定開回路電圧Ｅを更新し（ステップＳ１６ｄ）、この更新した想定開回路電圧について、上記ステップＳ１６ａに戻って、測定した端子電圧Ｖ（ｔ）から、想定した開回路電圧Ｅを減算する処理を行う。べき数βが−０．５となったときには（ステップＳ１６ｃのＹ）、べき数βが−０．５となったときの想定開回路電圧Ｅを当該期間の想定開回路電圧としてＲＡＭ２３ｂのデータエリア（記憶手段に相当する）に格納（ステップＳ１６ｅ）して一連の処理動作を終了し、図９のフローチャートに戻る。
【０１２２】
なお、図１０のフローチャートには記載はないが、決定した累乗近似式のべき数がなかなか−０．５とならないときには、累乗近似式の決定が予め定めた回数行われた時点での電圧値を当該期間の想定開回路電圧Ｅとして求めて一連の処理動作を終らせることもできる。また、図７のフローチャートと同様に、実測開回路電圧による充電状態の更新を行わせることがもできる。
【０１２３】
また、図１０のフローチャートでは、時間Ｔａ１から時間Ｔｂ４までの間において１０秒の一定間隔で測定を行っていることになっているが、１０秒毎の測定時以外の期間マイコンをスリープ状態にすることもできる。
【０１２４】
上記ステップＳ１６ｂにおける累乗近似式の決定の仕方は、図７のフローチャートのステップＳ５に関連して上述したと同様のものでよい。
【０１２５】
次に、上記ステップＳ１６ｄにおける想定開回路電圧の更新の仕方は、図８及び表１を参照して行った上述したと同様のものでよい。
【０１２６】
次に、本実施形態の開回路電圧推定動作（作用）について説明する。電流センサ１５の出力により、充放電の終了が検出されると、それから一定時間Ｔａ１が経過した時点から時間Ｔｂ４までの間、電圧センサ１７の出力を取り込むことによって、バッテリの端子電圧を端子電圧として周期的に測定し、これらの電圧値と充放電の終了後からの経過時間をＲＡＭ２３ｂのデータエリアに格納、記憶して収集する。
【０１２７】
収集された端子電圧に対しては予め定めた複数の期間が設定され、各期間の端子電圧Ｖ（ｔ）から想定開回路電圧Ｅを減算し、減算して求めた値から最小二乗法を適用して累乗近似式を決定する。決定した累積近似式α・ｔ^βのべき数βが−０．５となっているかどうかを判断し、べき数βが−０．５になっていないときには、想定開回路電圧Ｅを新しいものに更新して再度同様の処理を行って各期間の累乗近似式α・ｔ^βを決定する。以上の動作をべき数βが−０．５になるか、又は、略−０．５になるまで繰り返し行い、何れかが成立したとき、そのときの電圧値をその期間の想定開回路電圧として求めるようにする。なお、略−０．５になったことの確認は、累乗近似式の決定回数が所定回数となるか、又は、想定開回路電圧範囲が予め定めた範囲以下になったことで行うことができる。
【０１２８】
上述したように求めた各期間の想定開回路電圧は、累乗近似式α・ｔ^βの漸近線となっているので、バッテリの特性が多少異なっていてもそのまま適用することができる。しかも、充放電の終了から時間Ｔａ１〜Ｔｂ４の間、充放電電流が流れなければ、その都度、開回路電圧を推定することが可能になり、開回路電圧を推定できる頻度を多くすることができる。
【０１２９】
そして、本発明は、モータジェネレータが回生電力をバッテリに充電するようになっているハイブリットカーなどの車両において、バッテリの充電状態を適切に知り、効率的にバッテリを利用して燃費向上を図るために有効に適用できる。
【０１３０】
なお、本願明細書中においては、分極などの影響を受けた端子電圧を端子電圧とし、平衡状態のときの端子電圧を開回路電圧としている。
【０１３１】
更に、本実施形態では、表２の例では、充電又は放電が終了した後、８０分まで測定しているが、測定した端子電圧を読み込む際のアナログ−デジタル変換の分解能が５ｍＶ程度である場合には、６０分までの測定で十分であり、８０分まで測定することは必要ない。
【０１３２】
また、実施の形態では、Ｔａについては１０分、Ｔｂについては２０分間隔で設定しているが、この間隔は今以上に小さくすることもできる。一般的には、細分化により精度は向上するが、上述した間隔でも、隣接する期間の電圧差が十分に小さいので、今以上に細分化しても演算回数が増えることによる負担増加に比較して精度の面での向上は多くは望めない。
【０１３３】
また、本実施形態のバッテリ充電状態測定装置では、図７及び図９のフローチャートにおけるステップＳ２が請求項中の電圧測定手段２３ａ−２に対する処理となっており、図７のステップＳ４〜Ｓ８、図１０のステップＳ１６ａ〜Ｓ１６ｅが請求項中の開回路電圧推定手段２３ａ−３に対応する処理となっており、図７のステップＳ９が請求項中の演算手段２３ａ−４に対応する処理となっており、図７のステップＳ１０が請求項中の充電状態更新手段２３ａ−５に対応する処理となっている。なお、請求項中の積算式充電状態測定手段２３ａ−１に対応する処理については、フローチャートでの図示は省略している。
【０１３４】
【発明の効果】
以上説明したように、請求項１又は１６記載の発明によれば、バッテリの充電又は放電が終了した後、又は、バッテリに流れる電流が予め定めた一定値以下になった後の実質的な充放電が終了する毎に、その終了から短い時間の内に測定した端子電圧の推移により推定した開回路電圧に基づいて演算したバッテリの充電状態を用いて現在の充電状態が更新されて設定し直され、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式により、測定した充放電電流による加減算によって求めた充電状態に累積する可能性のある誤差を解消できるので、充放電電流を長期間にわたって連続的に積算することによる大きな累積誤差の発生を生じ難くして、バッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法及び装置を提供することができる。
【０１３５】
請求項２記載の発明によれば、バッテリの充電又は放電が実質的に終了した後、比較的短い時間内に測定したバッテリの端子電圧によって、予め定めた近似式が決定されたときの想定開回路電圧を開回路電圧として推定できるので、充電又は放電の終了から比較的短時間の内に推定できる車両のバッテリの開回路電圧に基づいてバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１３６】
請求項３〜５記載の発明によれば、バッテリの充電又は放電が実質的に終了した後、比較的短い時間内に測定したバッテリの端子電圧によって、累乗近似式の漸近線を開回路電圧として推定できるので、バッテリの充電又は放電が終了した後、比較的短い時間内に測定したバッテリの端子電圧の測定によって、累乗近似式の漸近線を求めて、これを開回路電圧として推定できるので、充電又は放電の終了から比較的短時間の内に推定できるバッテリの開回路電圧に基づいてバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１３７】
請求項６記載の発明によれば、バッテリの充電又は放電が実質的に終了した後、比較的短い時間内に測定したバッテリの端子電圧によって求めた想定開回路電圧のなかから最良のものを開回路電圧として推定できるので、この開回路電圧に基づいてバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１３８】
請求項７記載の発明によれば、充電又は放電が終了した後の所定時間内に、異なる複数の期間を網羅的に漏れなく設けて各期間の想定開回路電圧を求め、その中から精度の良い想定開回路電圧を見つけだすことができるので、これを用いて車両のバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１３９】
また、請求項８記載の発明によれば、端子電圧を測定して収集する期間を別途定めることが必要なく、また使用しない無駄な端子電圧の測定も行わなくてもよいので、車両のバッテリの充電状態のより正確な測定の負担を軽減することのできるバッテリ充電状態測定方法を提供することができる。
【０１４０】
請求項９記載の発明によれば、端子電圧を測定して収集する期間を別途定めることが必要なく、また使用しない無駄な端子電圧の測定も行わなくてもよいので、測定の負担を軽減することのできるバッテリ充電状態測定方法を提供することができる。
【０１４１】
請求項１０記載の発明によれば、隣接する期間の数に関係なく相対比較した上で、バッテリの開回路電圧を推定することができるので、測定期間に得られた端子電圧を無駄なく有効に利用して車両のバッテリの充電状態をより正確に測定できるバッテリの開回路電圧推定方法を提供することができる。
【０１４２】
請求項１１記載の発明によれば、バッテリの充電又は放電が実質的に終了した後、比較的短い時間内に測定したバッテリの端子電圧によって、予め定めた近似式が決定されたときの想定開回路電圧を開回路電圧として推定できるので、充電又は放電の終了から比較的短時間の内に推定できる車両のバッテリの開回路電圧に基づいてバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１４３】
請求項１２〜１４記載の発明によれば、バッテリの充電又は放電が実質的に終了した後、比較的短い時間内に測定したバッテリの端子電圧によって、累乗近似式の漸近線を開回路電圧として推定できるので、バッテリの充電又は放電が終了した後、比較的短い時間内に測定したバッテリの端子電圧の測定によって、累乗近似式の漸近線を求めて、これを開回路電圧として推定できるので、充電又は放電の終了から比較的短時間の内に推定できるバッテリの開回路電圧に基づいてバッテリの充電状態をより正確に測定できるバッテリ充電状態測定方法を提供することができる。
【０１４４】
請求項１５及び１７記載の発明によれば、推定開回路電圧に基づいて演算して求めた充電状態よりもより精度の良い実測開回路電圧に基づいて演算して求めた充電状態を用いて現在の充電状態を更新することができるので、推定開回路電圧だけを利用したものに比べてより正確に充電状態を測定できるようにしたバッテリ充電状態測定方法及び装置を提供することができる。
【図面の簡単な説明】
【図１】本発明のバッテリの開回路電圧推定バッテリ充電状態測定装置の基本構成を示すブロック図である。
【図２】本発明のバッテリの開回路電圧推定バッテリ充電状態測定方法を適用した本発明の一実施形態に係るバッテリの開回路電圧推定バッテリ充電状態測定装置の概略構成を一部ブロックにて示す説明図である。
【図３】充電の終了後のバッテリの端子電圧の変化を示すグラフである。
【図４】開回路電圧推定方法を説明するために使用する一グラフである。
【図５】開回路電圧推定方法を説明するために使用する他のグラフである。
【図６】本発明の方法の成立性を具体的に例示するためのグラフである。
【図７】図２中のマイコンがバッテリ充電状態測定のため予め定めたプログラムに従って行う処理を示すフローチャートである。
【図８】想定開回路電圧の更新の仕方を説明するために使用するグラフである。
【図９】図２中のマイコンが想定開回路電圧算出のため予め定めたプログラムに従って行う処理を示すフローチャートである。
【図１０】図９中の想定開回路電圧算出の具体的な処理を示すフローチャートである。
【符号の説明】
１５　　　　　　電流測定手段（電流センサ）
２３ａ−１　　　積算式充電状態測定手段（ＣＰＵ）
２３ａ−２　　　端子電圧測定手段（ＣＰＵ）
２３ａ−３　　　開回路電圧推定手段（ＣＰＵ）
２３ａ−４　　　演算手段（ＣＰＵ）
２３ａ−５　　　充電状態更新手段（ＣＰＵ）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for measuring the state of charge of a battery for measuring the state of charge of a battery.
[0002]
[Prior art]
In a so-called hybrid car, which runs using an engine that uses gasoline or light oil as a fuel and an electric motor that rotates using a battery as a power source, a so-called hybrid car is equipped with a battery mounted on the alternator while the engine is rotating. The battery is charged by the generated electric power, and discharged to supply electric power to the electric motor when the vehicle is driven with the engine stopped. For this reason, by properly grasping the state of charge of the battery and effectively using the battery power without rotating the engine more than necessary, it is possible to drive with the electric motor as a power source as much as possible, thereby improving fuel efficiency. It is very important in planning.
[0003]
As a method of grasping the state of charge of a battery, a method called a current integration (power integration) method of integrating a current during charging into a current state of charge and subtracting a current during discharging from the current state of charge is generally adopted. I have. Since this method integrates the amount of electricity charged and discharged by the battery, it is convenient to obtain the capacity of the battery represented by the amount of electricity (Ah). It is the mainstream when finding the state of charge inside.
[0004]
That is, in the current integration method, the Ah value X in the fully charged state according to the type of the vehicle-mounted battery is known in advance, and when the Ah value falls below the predetermined value Y, the battery is discharged further. Since it is also known that power should not be set, X is set to a charged state of 100%, Y is set to a charged state of 0%, and an Ah value Z per 1% is calculated in advance by (X−Y) / 100. The discharge current Id is measured at regular time intervals, and the integrated value obtained by adding or subtracting the Ah value obtained by multiplying each measured value by the certain time t or subtracting the Ah value from the current value expressed in% each time the Ah value Z becomes equal to or more than the Z value The charge state during use of the battery is obtained by making ± 1 the charge state x of the battery.
[0005]
However, in the case of this method, even if there is a slight error in the measured current or time, the error is accumulated, and if the error is continued for a long time, the measured state of charge greatly deviates from the actual state. As a result, the state of charge of the battery cannot be accurately grasped.
[0006]
Therefore, in order to more accurately grasp the state of charge, calculate the remaining capacity indicating the state of charge in order to perform calibration at appropriate timing, and correct the state of charge obtained by the current-time product with the calculated remaining capacity. What is performed is also proposed in, for example, JP-A-2002-51470 and Japanese Patent No. 3104483.
[0007]
In the former method, a map showing the relationship between the terminal voltage and the state of charge created based on the voltage characteristics in the no-load state is prepared, and a map search is performed based on the terminal voltage measured in the no-load state at any time. To calculate the remaining capacity in the charged state by calculation, and the latter method corrects the remaining capacity of the battery calculated based on the terminal voltage of the battery that has been stable for a predetermined period of time in a no-load state. Things.
[0008]
[Problems to be solved by the invention]
However, the former method assumes that the remaining capacity is calculated based on the terminal voltage when the no-load state is forcibly generated for a short period of time. The terminal voltage of the battery is not measured, so that a completely different remaining capacity is calculated even if the terminal voltage has the same value, and although the remaining capacity can be calculated frequently, the accuracy is extremely poor. There's a problem.
[0009]
In this respect, in the latter method, the remaining capacity is calculated using the terminal voltage measured at the time when the terminal voltage is stabilized, so that the remaining capacity can be calculated with high accuracy, and the state of charge is the current state. However, it takes a long time, for example, 24 hours, for the terminal voltage of the battery to become stable after the no-load state, and there is a problem that the correction can be made only when the vehicle is left for such a period of time. .
[0010]
Therefore, in view of the above-described current situation, the present invention makes it difficult to generate a large cumulative error by continuously integrating the charging / discharging current over a long period of time, and can more accurately measure the state of charge of the battery. It is an object to provide a method and an apparatus for measuring a state of charge.
[0011]
[Means for Solving the Problems]
The present invention has been made to solve the above problems, the terminal voltage of the battery after the end of charging and discharging, suddenly drops or rises immediately after the end of charging and discharging, a constant reflecting the state of charge with the progress of time The voltage value gradually changes toward the voltage value, and gradually approaches the voltage value within a relatively short time immediately after the end of charging and discharging, that is, the open circuit voltage can be estimated. The state of charge is calculated based on the calculated state of charge, and the calculated state of charge can be used to update the state of charge previously obtained by the current-time product method. The present invention relates to a battery state-of-charge measuring method, and the present invention according to claim 15 relates to a battery state-of-charge measuring device.
[0012]
According to the first aspect of the present invention, the charging current and the discharging current of a battery mounted and used on a vehicle running with an engine as a power source are periodically measured, and the periodically measured charging current is measured. Although the addition to the current state of charge of the battery and the subtraction of the periodically measured discharge current from the current state of charge of the battery are performed to measure the state of charge of the battery, the terminal voltage of the battery is measured. After the charging or discharging of the battery is completed, or after the current flowing in the battery becomes equal to or less than a predetermined constant value, that is, based on the transition of the terminal voltage measured after the charging or discharging of the battery is substantially completed. The open circuit voltage is estimated by calculating the state of charge of the battery based on the estimated open circuit voltage, and the current state of charge is calculated using the obtained state of charge. Since it is newly set, after the charging or discharging of the battery is completed, or every time the substantial charging / discharging after the current flowing through the battery becomes equal to or less than a predetermined constant value is completed, The current state of charge is updated and reset using the state of charge of the battery calculated based on the open circuit voltage estimated from the transition of the terminal voltage measured within a short time from the end, and the current state of charge is reset. Since the current value is updated and set to an accurate value, an error that may be accumulated in the state of charge obtained by addition / subtraction based on the measured charging / discharging current by the current integration method can be eliminated.
[0013]
According to a second aspect of the present invention, in the battery state-of-charge measuring method according to the first aspect, the terminal voltage is measured after the charging or discharging of the battery is completed or the current flowing through the battery is measured. After the predetermined constant value or less, after performing a predetermined time, performing a plurality of times during a certain time, the estimation of the open circuit voltage, the terminal voltage of the battery measured a plurality of times, By the difference value with the assumed open circuit voltage, the transition of the terminal voltage is predicted to determine a predetermined approximate expression, and the determined approximate expression is as predicted or abbreviated as predicted. Up to this point, the determination of the approximate expression is repeatedly performed while updating the assumed open circuit voltage, and the assumed open circuit voltage when the approximate expression becomes as predicted or when it is omitted as predicted is opened. Estimate circuit voltage It consists in battery state measuring method which comprises carrying out in the.
[0014]
According to the present invention described in claim 2, the terminal voltage is measured for a predetermined time after charging or discharging of the battery is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value. The open circuit voltage is estimated multiple times within a certain period of time after elapse, and the transition of the terminal voltage is estimated based on the difference between the battery terminal voltage measured multiple times and the assumed open circuit voltage. The predetermined approximate expression is determined, and the determination of the approximate expression is repeatedly performed while updating the assumed open-circuit voltage until the determined approximate expression becomes as predicted, or until the determined approximate expression becomes shorter as predicted, As the approximation formula is as predicted, or because it is performed by estimating the assumed open circuit voltage at the time of the abbreviation as predicted as the open circuit voltage, after the charging or discharging of the battery is substantially completed, Battery measured within a relatively short time By reactive terminal voltage it can be estimated assuming an open circuit voltage when predetermined approximate expression is determined as an open circuit voltage.
[0015]
According to a third aspect of the present invention, in the battery state-of-charge measuring method according to the second aspect, the determined approximate expression is a power approximate expression having a negative power, and the determined power approximate expression is a power approximate expression. Until the number becomes -0.5, or until approximately -0.5, the determination of the power approximation formula is repeatedly executed while updating the assumed open circuit voltage, and the exponent is -0.5 and Or the estimated open circuit voltage when the voltage becomes approximately -0.5 is estimated as an open circuit voltage.
[0016]
According to the third aspect of the present invention, the determined approximate expression is a power approximate expression having a negative power, and the power of the determined power approximate expression is -0.5 or approximately Until −0.5, the power approximation formula is repeatedly determined while updating the assumed open-circuit voltage. Assuming that the exponent is −0.5 or approximately −0.5. Since the open circuit voltage is estimated as the open circuit voltage, the asymptote of the power approximation formula is obtained by measuring the terminal voltage of the battery measured within a relatively short time after the charging or discharging of the battery is substantially completed. It can be estimated as an open circuit voltage.
[0017]
According to a fourth aspect of the present invention, in the battery state-of-charge measuring method according to the third aspect, when the measured terminal voltage is falling, the time is t, the unknown coefficient is α, and the unknown exponent is Is β, the power approximation equation is α · t ^β The method for measuring the state of charge of a battery is characterized in that:
[0018]
According to the fourth aspect of the present invention, when the measured terminal voltage is falling, if the time is t, the unknown coefficient is α, and the unknown power is β, the power approximation equation is α · t ^β And the power approximation α · t ^β Since the assumed open circuit voltage when the exponent β becomes −0.5 or becomes approximately −0.5 is estimated as the open circuit voltage, after the battery is substantially charged, By measuring the terminal voltage of the battery measured within a relatively short period of time, an asymptote of a power approximation formula is obtained, and this can be estimated as an open circuit voltage.
[0019]
According to a fifth aspect of the present invention, in the battery state-of-charge measuring method according to the third aspect, when the measured terminal voltage is increasing, the value for determining the power approximation formula is: Absolute value of the value obtained by subtracting the assumed open circuit voltage from the measured terminal voltage, where time is t, unknown coefficient is α, and unknown power number is β, the power approximation equation is α · t ^β The method for measuring the state of charge of a battery is characterized in that:
[0020]
According to the present invention, when the measured terminal voltage is rising, the value for determining the power approximation formula is an absolute value of a value obtained by subtracting the assumed open circuit voltage from the measured terminal voltage. When the time is t, the unknown coefficient is α, and the unknown power is β, the power approximation equation is α · t ^β And the power approximation α · t ^β Since the assumed open circuit voltage when the exponent β becomes -0.5 or becomes approximately -0.5 is estimated as the open circuit voltage, after the battery discharge is substantially finished, By measuring the terminal voltage of the battery measured within a relatively short period of time, an asymptote of a power approximation formula is obtained, and this can be estimated as an open circuit voltage.
[0021]
According to a sixth aspect of the present invention, in the battery state-of-charge measurement method according to the first aspect, the terminal voltage is measured and collected at a predetermined cycle, and the estimation of the open circuit voltage is performed by Obtained as a supposed open circuit voltage of each period a predetermined approximate expression asymptotically approximated based on the terminal voltage in each of a plurality of predetermined periods for the collected terminal voltage, The battery state-of-charge measurement method is characterized in that the method is performed by estimating the assumed open-circuit voltage in a period in which the difference between the assumed open-circuit voltage and the assumed open-circuit voltage in an adjacent period is minimized as an open-circuit voltage.
[0022]
According to the present invention as set forth in claim 6, the terminal voltage is measured at a predetermined cycle and collected, and the estimation of the open circuit voltage is determined based on a plurality of predetermined terminal voltages with respect to the collected terminal voltage. A voltage value in which a predetermined approximation approximated based on the terminal voltage in each period of the period asymptotically is obtained as an assumed open circuit voltage in each period, and a period in which the difference from the assumed open circuit voltage in the adjacent period is the smallest. The estimated open circuit voltage is estimated by estimating the open circuit voltage as an open circuit voltage, and after the charging or discharging of the battery is substantially completed, the assumed open circuit voltage obtained by the terminal voltage of the battery measured within a relatively short time. The best one can be estimated as the open circuit voltage.
[0023]
According to a seventh aspect of the present invention, in the battery state-of-charge measuring method according to the sixth aspect, a current flowing through the battery is determined in advance after charging or discharging is completed or in each of the plurality of periods. The battery state-of-charge measurement method is characterized in that it is determined by a combination of one of a plurality of start points and one of a plurality of end points, which are determined in advance according to a time after the predetermined value or less.
[0024]
According to the present invention described in claim 7, each of the plurality of periods is determined by a combination of one of the plurality of start points and one of the plurality of end points predetermined by the time after the end of charging or discharging. Therefore, within a predetermined time after the end of charging or discharging, a plurality of different periods are provided exhaustively without loss, and an assumed open circuit voltage in each period is obtained, and a precise open circuit voltage is found from among them. be able to.
[0025]
According to the present invention described in claim 8, in the battery state-of-charge measuring method according to claim 7, the shortest one of the start points and the longest one of the end points measure and collect the terminal voltage. A battery state-of-charge measuring method is characterized by corresponding to the start and end of a period.
[0026]
According to the present invention described in claim 8, since the shortest start point and the longest end point correspond to the start and end of the period for measuring and collecting the terminal voltage, the terminal voltage is measured. It is not necessary to separately determine the period for collecting data, and it is not necessary to measure unnecessary terminal voltages that are not used.
[0027]
According to a ninth aspect of the present invention, in the battery state-of-charge measuring method according to the seventh or eighth aspect, the shortest one of the start points and the longest one of the end points measure the terminal voltage. A battery state-of-charge measuring method is characterized in that it corresponds to the start and end of a collection period.
[0028]
According to the present invention described in claim 9, since the shortest start point and the longest end point correspond to the start and end of the period for measuring and collecting the terminal voltage, the terminal voltage is measured. It is not necessary to separately determine the period for collecting data, and it is not necessary to measure unnecessary terminal voltages that are not used.
[0029]
According to a tenth aspect of the present invention, in the battery state-of-charge measuring method according to any one of the sixth to ninth aspects, a sum of absolute values of a difference from the assumed open circuit voltage in an adjacent period is set to be adjacent. A battery state-of-charge measuring method is characterized in that a period in which the value divided by the number of periods is a minimum is a period in which the difference between the assumed open-circuit voltage in an adjacent period is the smallest.
[0030]
According to the tenth aspect of the present invention, the period in which the sum of the absolute values of the differences between the assumed open circuit voltage and the open circuit voltage in the adjacent period divided by the number of the adjacent periods is minimized, Since the period in which the difference from the open circuit voltage is the smallest is set, the open circuit voltage of the battery can be estimated based on a relative comparison regardless of the number of adjacent periods.
[0031]
Further, according to the present invention as set forth in claim 11, in the battery state-of-charge measuring method according to any one of claims 6 to 10, when the collected terminal voltage decreases, the terminal voltage in each of the periods is reduced. According to the difference value with the assumed open circuit voltage, a predetermined power approximate expression having a negative power is determined, and the power of the determined power approximate expression is -0.5 or approximately- Determining the voltage value at which the power approximation asymptotically is obtained by repeatedly executing the determination of the power approximation expression while updating the assumed open circuit voltage until the value becomes 0.5. Exists.
[0032]
According to the eleventh aspect of the present invention, when the collected terminal voltage is falling, that is, when the terminal voltage is after the end of charging, the terminal voltage in each period is assumed. Based on the difference value with the open circuit voltage, a predetermined power approximate expression having a negative power is determined, and the power of the determined power approximate expression is -0.5, or approximately -0.5. By repeatedly executing the determination of the power approximation formula while updating the assumed open circuit voltage until the power approximation formula is obtained, the power approximation formula obtains the asymptotic voltage value. Within an extremely short time, the asymptote of the power approximation formula of each period can be obtained as the assumed open circuit voltage of each period.
[0033]
According to a twelfth aspect of the present invention, in the battery state-of-charge measuring method according to any one of the sixth to tenth aspects, when the collected terminal voltage increases, the terminal voltage of each period is reduced. By the absolute value of the value obtained by subtracting the assumed open circuit voltage, a predetermined power approximate expression having a negative power is determined, and the power of the determined power approximate expression is -0.5, or , By repeatedly executing the determination of the power approximation formula while updating the assumed open circuit voltage until the power approximation formula becomes approximately -0.5, thereby obtaining a voltage value at which the power approximation formula asymptotically approaches. State measurement method.
[0034]
According to the present invention described in claim 12, when the collected terminal voltage is rising, that is, when the terminal voltage is after the end of discharge, it is assumed from the terminal voltage in each period. Based on the absolute value of the value obtained by subtracting the open circuit voltage, a predetermined power approximation formula whose power is negative is determined by the difference between the terminal voltage of each period and the assumed open circuit voltage, and the determined power is determined. By repeatedly executing the determination of the power approximate expression while updating the assumed open circuit voltage until the power of the approximate expression becomes -0.5 or approximately -0.5, the power approximate expression becomes asymptotic. Since the assumed open circuit voltage is calculated, the asymptote of the power approximation of each period can be obtained as the assumed open circuit voltage of each period within a relatively short time after the battery discharge is completed.
[0035]
According to a thirteenth aspect of the present invention, in the battery state-of-charge measuring method according to the eleventh or twelfth aspect, in the method of estimating the open circuit voltage of the battery, the time is t, the unknown coefficient is α, and the unknown negative If the exponent is β, the power approximation formula is α · t ^β The method for measuring the state of charge of a battery is characterized in that:
[0036]
According to the present invention, when the time is t, the unknown coefficient is α, and the unknown negative power is β, the power approximation equation is α · t ^β , The power approximation formula α · t ^β The assumed open circuit voltage when the exponent β becomes −0.5 or substantially −0.5 can be used as the assumed open circuit voltage in that period.
[0037]
According to a fourteenth aspect of the present invention, in the battery state-of-charge measuring method according to the fourth, fifth or thirteenth aspect, the terminal voltage is set to an arbitrary number of 2 or more, and the arbitrary number of terminal voltages is subjected to a regression calculation process. And determining a power exponent β of the power approximation formula.
[0038]
According to the present invention described in claim 14, the terminal voltage is an arbitrary number of 2 or more, and the arbitrary number of terminal voltages is subjected to regression calculation processing to determine the exponent β of the power approximation. α ・ t ^β Even if the exponent β does not become −0.5, the assumed open circuit voltage can be obtained when the power approximation equation is determined a predetermined number of times.
[0039]
According to a fifteenth aspect of the present invention, in the battery state-of-charge measuring method according to any one of the first to fourteenth aspects, after the charging or discharging of the battery is completed, or the current flowing through the battery is previously determined. When the terminal voltage of the battery is in the state continuously for a predetermined period of time after the voltage becomes equal to or less than the predetermined fixed value, the open circuit voltage is measured by measuring the terminal voltage of the battery. 15. The battery according to claim 1, wherein the state of charge of the battery is calculated and calculated based on an open circuit voltage, and the current state of charge is updated and set using the calculated state of charge. The present invention resides in any one of the battery state-of-charge measuring methods described above.
[0040]
According to the invention described in claim 15, after the charging or discharging of the battery is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value, the predetermined terminal voltage of the battery is stabilized. When the battery is in the state continuously for a period of time, the open circuit voltage is measured by measuring the terminal voltage of the battery, and the state of charge of the battery is calculated and calculated based on the actually measured open circuit voltage. Is used to update and set the current state of charge, so that the current state of charge can be updated using a more accurate state of charge than the state of charge calculated based on the estimated open circuit voltage. it can.
[0041]
Further, according to the present invention, as shown in the basic configuration diagram of FIG. 1, the charging current and the discharging current of a battery mounted and used on a vehicle running with an engine as a power source are periodically changed. Current measuring means 15 for measuring; adding the charging current periodically measured by the current measuring means to the current state of charge of the battery; and calculating the current of the battery based on the discharging current periodically measured by the current measuring means. A charging state measuring means 23a-1 for measuring the state of charge of the battery by performing subtraction from the state of charge of the battery, respectively, and a voltage measuring means 23a-2 for measuring the terminal voltage of the battery. And after the charging or discharging is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value, the measured end. Open circuit voltage estimating means 23a-3 for estimating an open circuit voltage based on a change in voltage; and calculating means 23a- for calculating the state of charge of the battery based on the open circuit voltage estimated by the open circuit estimating means. 4 and a state-of-charge updating means 23a-5 for updating and setting the current state of charge using the state of charge determined by the arithmetic means.
[0042]
According to the present invention, the charging current periodically measured by the current measuring means 15 is added to the current state of charge of the battery, and the current of the discharging current periodically measured by the current measuring means 15 is used for the battery. Is subtracted from the state of charge of the battery, and the integrated state-of-charge measuring means 23a-1 measures the state of charge of the battery. The open circuit voltage estimating means 23a-3 based on the transition of the terminal voltage measured by the voltage measuring means 23a-2 after the charging or discharging is completed or after the current flowing through the battery becomes equal to or less than a predetermined constant value. Estimates the open circuit voltage, and the calculating means 23a-4 calculates and calculates the state of charge of the battery based on the estimated open circuit voltage. Since the current state of charge is updated and set by the state-of-charge updating means 23a-5 using the state-of-charge obtained by the arithmetic means 23a-4, the possibility of accumulation in the state of charge by addition / subtraction based on the measured charge / discharge current. Error after the completion of charging or discharging of the battery, or each time the substantial charging / discharging after the current flowing through the battery becomes equal to or less than a predetermined constant value, for a short time after the completion. The current state of charge is updated and reset using the state of charge of the battery calculated based on the open circuit voltage estimated from the transition of the terminal voltage measured within, and the current state of charge is updated to an accurate value. The error accumulated in the state of charge previously obtained by the current integration method can be eliminated.
[0043]
According to a seventeenth aspect of the present invention, in the battery state-of-charge measuring device according to the sixteenth aspect, the voltage measuring means is configured to determine whether the current flowing through the battery after charging or discharging of the battery is completed or When the terminal voltage of the battery is in the state continuously for a predetermined period of time after the battery terminal voltage is stabilized after the voltage becomes equal to or less than a predetermined constant value, the terminal voltage of the battery is measured, and the arithmetic unit measures the measured terminal voltage. The state of charge of the battery is calculated and obtained as a measured open circuit voltage, and the state of charge updating means updates and sets the current state of charge using the state of charge determined based on the measured open circuit voltage. The present invention resides in a battery state-of-charge measuring device.
[0044]
According to the present invention described in claim 17, after the charging or discharging of the battery is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value, the predetermined terminal voltage of the battery is stabilized. When the battery is in this state continuously for a period of time, the voltage measuring means measures the terminal voltage of the battery, and the computing means calculates and calculates the state of charge of the battery using the measured terminal voltage as the actually measured open circuit voltage, and updates the state of charge. Since the means updates and sets the current state of charge using the state of charge determined based on the measured open circuit voltage, it uses a more accurate state of charge than the state of charge calculated based on the estimated open circuit voltage. The current state of charge can be updated.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, before describing the battery state-of-charge measuring method according to the present invention together with one embodiment of the battery state-of-charge measuring apparatus according to the present invention with reference to FIG. 2, the basic concept of the present invention will be described.
[0046]
For example, when the charging of the battery mounted on the vehicle is completed, the terminal voltage in the open state of the battery gradually decreases due to the increase due to the concentration polarization with time, and as shown in FIG. For example, it changes so as to approach the open circuit voltage EO which is the terminal voltage in the equilibrium state of the battery after 24 hours, and such an asymptotic curve is generally expressed by a power equation.
[0047]
Therefore, when the open circuit voltage EO is unknown, the assumed open circuit voltage E is determined as shown in FIG. 4, and the assumed open circuit voltage E is subtracted from the terminal voltage V (t). , The power approximation α · t asymptotic to the horizontal axis ^β Will be represented by Further, the diffusion phenomenon is represented by a power approximation α · t ^β Approximately, the exponent β is considered to be near −0.5.
[0048]
Therefore, after the charging of the battery is completed, as shown in FIG. 5, the terminal voltage of the battery is measured for a predetermined time Tb of, for example, 15 minutes after a predetermined time Ta of 5 minutes has passed. Then, the assumed open circuit voltage E is subtracted from the measured terminal voltage to obtain a power approximation α · t. ^β Is calculated.
[0049]
In general, the diffusion phenomenon is represented by a power approximation α · t ^β Approximately, the exponent β is considered to be near −0.5. Since the change in the open circuit voltage after the end of charging can be caused by the voltage change caused by the diffusion of the electrolyte, the power approximation α · t such that the exponent β becomes −0.5 ^β Can be regarded as an open circuit voltage.
[0050]
On the other hand, when the discharge of the battery is completed, the terminal voltage in the open state of the battery gradually increases by eliminating the drop due to the concentration polarization with time and, for example, the equilibrium of the battery after 24 hours. It approaches the open circuit voltage EO which is the terminal voltage in the state. In the case of discharging, the assumed open circuit voltage E is calculated by the power approximation α · t. ^β Since the value is always larger, the value obtained by subtracting the assumed open circuit voltage E from the measured terminal voltage becomes negative. Therefore, the power approximation α is obtained by using the absolute value of the value obtained by subtracting the assumed open circuit voltage E from the terminal voltage.・ T ^β Is calculated.
[0051]
Generally, after charging or discharging is completed, the terminal voltage of the battery is measured a plurality of times during a predetermined time after a predetermined time has elapsed, and the assumed open circuit voltage is calculated from the measured terminal voltage. Based on the subtracted value, a predetermined power approximate expression having a negative power is determined, and until the power of the determined power approximate expression becomes -0.5, the power approximate is determined. It may be updated and repeatedly executed, and the assumed open circuit voltage when the exponent becomes −0.5 may be estimated as the open circuit voltage.
[0052]
In addition, even if the assumed open circuit voltage is updated a predetermined number of times and repeatedly executed, if the exponent does not become −0.5 in some cases, the exponent becomes approximately −0 by executing the predetermined number of times. .5 is determined, the assumed open circuit voltage at this time is estimated as an open circuit voltage, and it is possible to eliminate the need to repeat the processing for determining the power approximation formula more than necessary.
[0053]
In addition, after charging / discharging is stopped, for example, after a predetermined time Ta of 5 minutes has elapsed, sampling of the terminal voltage is started because the voltage change immediately after charging / discharging includes internal resistance, activation polarization, This is because a voltage change that is not related to the diffusion of the electrolyte, such as an overvoltage due to gas generation, is included, and sampling this change is an error factor, and is not included in the data for obtaining the power approximation formula. .
[0054]
The sampling is performed up to the time Tb not only for the sake of convenience, but also because there is a possibility that the accuracy of the estimation of the open-circuit voltage may be reduced depending on the resolution of the measurement due to the decrease in the voltage change over time. This is because the influence of the voltage drop due to the dark current of the vehicle increases with time.
[0055]
As described above, the diffusion phenomenon is represented by the power approximation α · t. ^β FIG. 6 shows a specific example that demonstrates that the exponent β is close to −0.5. When the battery has an open circuit voltage of 12.34 V, the assumed open circuit voltage is 12.34 V In the power approximation equation determined using the value obtained by subtracting the terminal voltage measured after the charging was stopped, the exponent is -0.500, while the estimated open circuit voltage is 12.34 V For a smaller value of 12.29 V, the exponent is -0.452, which is greater than -0.500, and for a value of 12.39 V, which is greater than 12.34 V, the exponent is -0.559, which is smaller than -0.500. This indicates that when the exponent of the power approximation becomes -0.5, the assumed open circuit voltage becomes equal to the open circuit voltage.
[0056]
Returning to the original drawing, FIG. 2 is an explanatory diagram showing, in partial blocks, a schematic configuration of a battery charge state measuring device according to an embodiment of the present invention to which the battery charge state measuring method of the present invention is applied. The battery state-of-charge measuring device of the present embodiment is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3.
[0057]
Normally, this hybrid vehicle travels by transmitting only the output of the engine 3 from the drive shaft 7 to the wheels 11 via the differential case 9 at normal times, and drives the motor generator 5 with electric power from the battery 13 at high load. , And the output of the motor generator 5 in addition to the output of the engine 3 is transmitted from the drive shaft 7 to the wheels 11 to perform the assist traveling.
[0058]
Further, the hybrid vehicle is configured so that the motor generator 5 functions as a generator (generator) during deceleration or braking, and converts the kinetic energy into electric energy to charge the battery 13.
[0059]
The motor generator 5 is further used as a cell motor for forcibly rotating a flywheel of the engine 3 when the engine 3 is started when a starter switch (not shown) is turned on. Large current is passed through. When the engine 3 is started by the motor generator 5 when the starter switch is turned on, the starter switch is turned off and the ignition switch and the accessory switch are turned on with the release of the operation of an ignition key (not shown). Accordingly, the discharge current flowing from the battery 13 shifts to a steady current.
[0060]
The battery state-of-charge measuring device 1 of the present embodiment includes a discharge current I of the battery 13 for electrical components such as a motor generator 5 functioning as a motor for assisted driving and a cell motor, and a battery 13 from the motor generator 5 functioning as a generator. It includes a current sensor 15 for detecting a charge / discharge current, and a voltage sensor 17 having a resistance of about 1 M ohm and connected in parallel with the battery 13 and detecting a terminal voltage V of the battery 13.
[0061]
Further, in the battery state-of-charge measuring device 1 of the present embodiment, the outputs of the above-described current sensor 15 and voltage sensor 17 are captured after A / D conversion in an interface circuit (hereinafter abbreviated as “I / F”) 21. A microcomputer (hereinafter abbreviated as “microcomputer”) 23 is further provided.
[0062]
The microcomputer 23 has a CPU 23a, a RAM 23b, and a ROM 23c. Among these, the I / F 21 is connected to the CPU 23a in addition to the RAM 23b and the ROM 23c. Switches, ignition switches and accessory switches, and switches for electrical components (loads) other than the motor generator 5 are further connected.
[0063]
The RAM 23b has a data area for storing various data and a work area used for various processing operations, and the ROM 23c stores a control program for causing the CPU 23a to perform various processing operations.
[0064]
The current value and the voltage value, which are the outputs of the current sensor 15 and the voltage sensor 17, are taken into the CPU 23a of the microcomputer 23 via the I / F 21.
[0065]
Next, a battery open circuit voltage estimation process performed by the CPU 23a according to the control program stored in the ROM 23c will be described with reference to FIG.
[0066]
It is assumed that the microcomputer 23 has been activated by receiving the power supply from the battery 13, and the microcomputer 23 determines whether the current value is 0 based on the current value obtained by sampling the output of the current sensor 15, for example. , It is determined whether the charging or discharging is completed. As a result of this determination, when the end of charging or discharging is detected, the open circuit voltage estimation processing shown in the flowchart of FIG. 7 is started. In this open circuit voltage estimation process, first, it is determined whether a predetermined time Ta of, for example, 5 minutes has elapsed from the end of charging or discharging (step S1).
[0067]
If the time has not elapsed, the process waits until the time has elapsed, and if the time has elapsed (Y in step S1), the terminal voltage of the battery is then changed by the output of the voltage sensor 16 at regular intervals of, for example, 10 seconds. The voltage is sampled and stored in a data area (corresponding to storage means) of the RAM 23b (step S2). This sampling is continued until a predetermined time Tb of, for example, 15 minutes elapses from the end of charging or discharging (N in step S3).
[0068]
When the time Tb has elapsed (Y in step S3), the difference between the measured terminal voltage V (t) and the assumed open circuit voltage E, that is, in the case of charging, the measured terminal voltage V ( The value obtained by subtracting the assumed open circuit voltage E from t), and the absolute value of the value obtained by subtracting the assumed open circuit voltage E from the measured terminal voltage V (t) in the case of discharge (step S4). A power approximation process is performed on the obtained value f (t) to determine a predetermined power approximate expression having a negative power number (step S5).
[0069]
When the power approximate expression is determined, it is determined whether or not the power exponent β of the next determined power approximate expression is equal to -0.5 (step S6). As a result of this determination, the exponent β becomes -0.5. If not (N in step S6), the assumed open-circuit voltage E is updated (step S7). The updated assumed open-circuit voltage is returned to step S4, and the assumed open-circuit voltage is estimated from the measured terminal voltage V (t). A process of subtracting the obtained open circuit voltage E is performed. When the exponent β becomes −0.5 (Y in step S6), the assumed open circuit voltage E when the exponent β becomes −0.5 is estimated as an open circuit voltage (step S8). Thereafter, the state of charge of the battery is calculated based on the estimated open circuit voltage (step S9), and the current state of charge is updated and reset using the calculated state of charge (step S10).
[0070]
In step S10, the current state of charge is updated and reset using the state of charge calculated in step S9 based on the open circuit voltage estimated in step S8. At regular intervals, based on the current value obtained by sampling the output of the current sensor 15, it is determined whether or not the state in which charging or discharging has been completed is continued by determining whether or not the current value is 0 ( Step S10a). When it is continued (Y in step S10a), the state is continuously changed for a predetermined time, for example, 24 hours, in which various polarizations generated by charging and discharging are eliminated and the terminal voltage of the battery is stabilized. It is determined whether or not it is (Step S10b). When the state in which charging and discharging have been substantially stopped has continued for a certain period of time or more (Y in step S10b), the open circuit voltage is measured by measuring the terminal voltage of the battery (step S10c). The actually measured open circuit voltage is used in step S9 to calculate the state of charge instead of the estimated open circuit voltage, and the state of charge obtained by calculation based on the actually measured open circuit voltage is determined in step S10. It is used to update the current state of charge and reset it.
[0071]
As described above, since the state in which charging and discharging are stopped continues for a certain period of 24 hours, it is determined that the terminal voltage of the battery is in a stable state reflecting the state of charge of the battery, and the open circuit voltage is automatically determined. Is measured and the current state of charge is updated based on the state of charge calculated based on the measured open circuit voltage.Therefore, the frequency is lower than when using the estimated open circuit voltage, but the accuracy is higher than that. Can be reset to a good charge state. Although not shown in the flowchart, when the current state of charge is updated based on the state of charge obtained based on the measured open circuit voltage, the process is ended there to prevent useless processing.
[0072]
The calculation of the state of charge of the battery based on the estimated open circuit voltage is performed using a relational expression or a table predetermined based on a known relationship between the open circuit voltage and the state of charge in the equilibrium state. When the battery has some kind of deterioration, it is possible to obtain a dischargeable charge state by separately grasping the deterioration and performing an operation in consideration of the deterioration.
[0073]
Although not described in the flowchart, when the power of the determined power approximate expression does not easily become −0.5, the power approximate expression is determined a predetermined number of times, not shown in the flowchart of FIG. A series of processing operations can be terminated by estimating the assumed open circuit voltage E at the time when the open circuit voltage is reached.
[0074]
Although not described in the flowchart, the sampling performed from the time Ta to the time Tb is performed at a constant interval of 10 seconds, but the sampling cycle is shortened, for example, three times from the time Ta to the time Tb. It is also possible to read the same number of terminal voltages as when sampling at equal intervals, and to put the microcomputer in a sleep state during a period in which sampling is not performed.
[0075]
The method of determining the power approximation in step S5 will be described below. Power approximation y = α · x ^β Is
ln (y) = ln (α) + β · ln (x)
It can be. Now, if ln (y) = Y, ln (α) = A, and ln (x) = X,
Y = A + β · X
It becomes the equation of the straight line.
A and β are obtained as follows by regression analysis.
[0076]
If the difference between the approximate expression and the actual data is ε,
Yi = A + β · Xi + εi (i = 1, 2,..., N)
It can be. Since it is sufficient to find A and β that minimize εi as a whole, A and β that minimize the sum of εi2 are found.
[0077]
The above is a description of the least squares method. According to the least squares method, it is expressed by the following equation.
δΣεi / δA = 0
δΣεi / δβ = 0
Solving this system of equations gives
ΣYi-βΣXi-ΣA = 0
ΣXiYi-βΣXi2-AΣXi = 0
This allows
β = (ΣXiYi−nXaYa) / (ΣXi2-nXa2)
A = Ya-βXa
[0078]
Xi is X-axis data, Yi is Y-axis data, n is the number of data, Xa is the average value of Xi, and Ya is the average value of Yi. As described above, since A = ln (α),
α = eA
Therefore, the power approximation formula y = α · x ^β Can be requested.
[0079]
Next, a method of updating the assumed open circuit voltage in step S7 will be described with reference to FIG.
[Table 1]

[0080]
When estimating the open circuit voltage after the end of charging and discharging, the assumed open circuit voltage is updated by a method generally called a binary tree search method. First, as shown in FIG. 8, the assumed open-circuit voltage is, for example, the case of an upper assumed open-circuit voltage V (Tb), a lower assumed open-circuit voltage 0, and an intermediate assumed open-circuit voltage V (Tb) / 2. Perform power approximation.
[0081]
Β (V (Tb)), β (0), and β (V (Tb) / 2) obtained from the respective approximations are compared with each other to determine whether β of the intermediate assumed open circuit voltage is equal to −0.5, If not equal, a comparison is made as to whether it is larger or smaller than -0.5. When β of the intermediate assumed open circuit voltage is not −0.5, the range including the data of −0.5 is included. In the example of Table 1, the range between the intermediate assumed open circuit voltage and the upper limit assumed open circuit voltage is The β of the assumed open circuit voltage (V (Tb) + V (Tb) / 2) / 2 divided into two ranges is calculated, and the comparison operation is repeated until β = −0.5. Table 1 shows a specific example. In the example of Table 1, even when the number of searches is other than 1, the exponent β of each of the lower limit, the middle, and the upper limit is calculated and obtained. However, in the second and subsequent searches, the calculation of the exponent β may be performed only at the middle.
[0082]
In addition, even if the assumed open circuit voltage is updated and repeatedly executed, when the exponent is sometimes not equal to -0.5, the numerical value of the lower third assumed open circuit voltage and the upper limit assumed open circuit voltage in the third digit after the decimal point is changed. When there is no more than about one, it is determined that the exponent has become approximately -0.5, the assumed open circuit voltage at this time is estimated as an open circuit voltage, and the process of determining a power approximation formula more than necessary is repeated. Can be eliminated.
[0083]
The first upper limit assumed open circuit voltage is set to V (Tb) because the open circuit voltage does not become higher than V (Tb). The lower limit assumed open circuit voltage may be the open circuit voltage at the time of completion of discharge (capacity 0%). However, when overdischarge is performed, the open circuit voltage at the time of completion of discharge (capacity 0%) is lower than the open circuit voltage. Since there is a possibility, the initial value is set to 0V.
[0084]
Next, an open circuit voltage estimation operation (operation) of the present embodiment will be described. First, when electrical components (loads) other than the motor generator 5 of the hybrid vehicle are operating or the motor generator 5 is operating to function as a motor, the battery 13 is discharging. When operating to function as a generator, the battery 13 is being charged. The charge / discharge of the battery can be detected by taking in the output of the current sensor 15, and the end of the charge / discharge can also be detected by the output of the current sensor 15 being equal to or less than a predetermined value.
[0085]
When the end of charging / discharging is detected from the output of the current sensor 15, the output of the voltage sensor 17 is taken in from the time when a certain time Ta has elapsed to the time Tb, so that the terminal voltage of the battery is used as the terminal voltage. These voltage values are measured periodically, and the voltage values and the elapsed time from the end of charge / discharge are stored, stored, and collected in the data area of the RAM 23b. The assumed open-circuit voltage E is subtracted from the collected terminal voltage V (t), and the power approximate expression is determined by applying the least squares method from the value obtained by the subtraction. The determined cumulative approximation formula α · t ^β Is determined to be -0.5, and if the exponent β is not -0.5, the assumed open circuit voltage E is updated to a new one and the same processing is performed again. Power approximation α · t ^β To determine. The above operation is repeated until the exponent β becomes −0.5 or approximately −0.5, and when either of them is satisfied, the assumed open circuit voltage at that time is estimated as the open circuit voltage. To do. It should be noted that the confirmation that the value has become approximately -0.5 can be performed when the number of determinations of the power approximation becomes a predetermined number or when the assumed open circuit voltage range becomes equal to or less than a predetermined range. .
[0086]
The open circuit voltage estimated as described above is calculated by the power approximation α · t ^β Therefore, even if the times Ta and Tb are different, they do not move. Therefore, even if the characteristics of the battery are slightly different, the present invention can be applied as it is. In addition, if the charging / discharging current does not flow during the period from Ta to Tb from the end of charging / discharging, the open circuit voltage can be estimated each time, and the frequency at which the open circuit voltage can be estimated can be increased. .
[0087]
The present invention provides a vehicle, such as a hybrid car, in which a motor generator charges regenerative power to a battery, in order to appropriately know the state of charge of the battery and improve fuel efficiency by efficiently using the battery. Can be applied effectively.
[0088]
In this specification, a terminal voltage affected by polarization or the like is defined as a terminal voltage, and a terminal voltage in an equilibrium state is defined as an open circuit voltage.
[0089]
In this embodiment, the case where the open circuit voltage of the battery is estimated in the hybrid vehicle has been described. However, the present invention is applied to a general 14V vehicle, a multiple power supply vehicle such as 14V and 42V, an electric vehicle, and a normal gasoline vehicle. Needless to say, the present invention is applicable to estimation of the open circuit voltage of a battery mounted on various vehicles.
[0090]
By the way, in general, a change in the terminal voltage of the battery immediately after charging / discharging includes a voltage change unrelated to the diffusion of the electrolyte, such as an internal resistance, an activation polarization, an overvoltage accompanied by gas generation, and an error. In any case, it is meaningless to measure and collect the terminal voltage during the period including the voltage change unrelated to the diffusion of the electrolytic solution.
[0091]
In general, the estimation accuracy may be reduced depending on the resolution of the measurement because the voltage change becomes smaller as time elapses, so that in any case, the resolution is too low and the estimation accuracy is low. As for the terminal voltage, there is no point in measuring the terminal voltage any further.
[0092]
Therefore, in order to exclude the measurement of the period causing the error, which includes the voltage change not related to the diffusion of the electrolyte, the measurement start point of the terminal voltage is set to be after a predetermined time Ta has elapsed from the end of the charge / discharge. However, depending on the condition of the battery, the time at which the error factor is eliminated differs.If the error is uniformly determined, depending on the battery condition, it is impossible to measure and use the terminal voltage without the error factor, or It measures and uses the terminal voltage that has a problem.
[0093]
In addition, in order to exclude the measurement after entering the period in which the estimation accuracy is reduced due to the resolution of the measurement, the terminal end point of the measurement of the terminal voltage may be set as a point after a predetermined time Tb has elapsed from the end of the charge / discharge. Is a problem due to the magnitude of an error factor between terminal voltages used for performing power approximation. In other words, the size of the error factors included in the other terminal voltages used for the power approximation becomes a problem.If uniformly determined, the terminal voltage with a resolution that does not matter depending on the condition of the battery is used. It cannot be used, or the terminal voltage of the resolution of interest is measured and used.
[0094]
Of course, it is conceivable to set a period in which the error factor does not enter regardless of the state of the battery. However, if the measurement period is determined in advance based on such an idea, the measurement period does not exist. Or the specified period is not always appropriate.
[0095]
Therefore, a concept for accurately estimating the open circuit voltage of the battery regardless of the state of the battery will be described below.
[0096]
First, as a predetermined time Ta from the end of charge / discharge defining the measurement start point of the terminal voltage, the charge / discharge determining the measurement end point of the terminal voltage is, for example, 5 minutes as early as possible to measure the terminal voltage when the error factor is quickly eliminated. Is set as a predetermined time Tb from the end of, for example, 80 minutes, which is a later time that can also measure the terminal voltage when the resolution is slightly reduced, and is set to, for example, 10 seconds during the measurement period of the predetermined time Ta to Tb from the end of charging and discharging. The terminal voltage is measured at a predetermined period, and the measured terminal voltage is collected by storing it in a memory.
[0097]
After the charging / discharging is stopped, for example, after a predetermined time Ta of 5 minutes has elapsed, the sampling of the terminal voltage is started because the voltage change immediately after charging / discharging includes internal resistance, activation polarization, This is because a voltage change that is not related to the diffusion of the electrolyte, such as an overvoltage due to gas generation, is included, and sampling this change is an error factor, and is not included in the data for obtaining the power approximation formula. .
[0098]
The reason why the sampling is performed up to the predetermined time Tb of, for example, 80 minutes is not only for the sake of convenience, but also because the voltage change over time becomes small, and depending on the resolution of the measurement, the estimation accuracy of the open circuit voltage may be reduced. This is because the influence of the voltage drop due to the dark current of the vehicle increases with time.
[0099]
Next, in order to determine a plurality of periods in advance for the terminal voltage measured and collected during the measurement period of the predetermined time Ta to Tb from the end of the charge / discharge, 5 corresponding to the predetermined time Ta (5 minutes) The minute is defined as the shortest point Ta1, and a certain time of, for example, 10 minutes is added to 10 minutes to determine Ta2 (15 minutes), Ta3 (25 minutes), Ta4 (35 minutes), and Ta5 (45 minutes). In accordance with the time Tb (80 minutes), 80 minutes is set as the longest point Tb4, and a certain time of 20 minutes is subtracted therefrom to determine Tb3 (60 minutes), Tb2 (40 minutes), and Tb1 (20 minutes). Then, Ta1 (5 minutes), Ta2 (15 minutes), Ta3 (25 minutes), Ta4 (35 minutes), and Ta5 (45 minutes) are set as one of the start points of each period, and Tb4 (80 minutes) and Tb3 ( 60 minutes), Tb2 (40 minutes), and Tb1 (20 minutes) are used as one of the end points of each period, respectively, and the collected terminals are obtained by combining one of the plurality of start points and one of the plurality of end points. A plurality of periods are predetermined for the voltage.
[0100]
That is, with respect to the terminal voltage measured and collected during the measurement period of the predetermined time Ta to Tb from the end of charging and discharging, Ta1 (5 minutes)-[Tb4 (80 minutes), Ta2 (15 minutes)-[Tb4 (80 minutes), Tb3 (60 minutes), Tb2 (40 minutes) or Tb1 (20 minutes)], Ta3 (25 minutes)-[Tb4 (80 minutes), Tb3 (60 minutes) or Tb2 (40 minutes)], 16 different periods of Ta4 (35 minutes)-[Tb4 (80 minutes), Tb3 (60 minutes) or Tb2 (40 minutes)], Ta5 (45 minutes)-[Tb4 (80 minutes) or Tb3 (60 minutes) Can be set exhaustively without omission.
[0101]
Since the shortest point of the start point and the longest point of the end point correspond to the start and end points of the period for measuring and collecting the terminal voltage, a separate period for measuring and collecting the terminal voltage should be provided separately. Is not required. In addition, since the interval between a plurality of start points is made smaller than the interval between a plurality of end points, a voltage change that is not related to the diffusion of the electrolyte, such as an internal resistance, an activation polarization, and an overvoltage accompanied by gas generation, is included. In addition, it is possible to set a more detailed period for a portion near immediately after charging or discharging, which is likely to be an error factor.
[0102]
Therefore, after charging / discharging of the battery is completed, the terminal voltage of the battery is measured at a cycle of, for example, 10 seconds after a lapse of a predetermined time Ta of, for example, 5 minutes, to a predetermined time Tb of, for example, 80 minutes. And collect. The exponent approximated to the measured and collected terminal voltage based on the terminal voltage in each of a plurality of predetermined periods is -0.5 or approximately -0.5. The voltage value at which the power approximation is asymptotic is determined as the assumed open circuit voltage in each period.
[0103]
In particular, when the battery has been charged, as shown in FIG. 5, the assumed open circuit voltage E is subtracted from the collected terminal voltage in each period, and the power approximate expression α · t in each period is subtracted. ^β Is calculated.
[0104]
On the other hand, when the discharge of the battery is completed, the terminal voltage in the open state of the battery gradually increases by eliminating the drop due to the concentration polarization with time and, for example, the equilibrium of the battery after 24 hours. It approaches the open circuit voltage EO which is the terminal voltage in the state. As described above, in the case of discharging, the assumed open circuit voltage E is calculated by the power approximate expression α · t. ^β Since the value is always larger, the value obtained by subtracting the assumed open circuit voltage E from the measured terminal voltage in each period is negative. Therefore, each value is calculated using the absolute value of the value obtained by subtracting the assumed open circuit voltage E from the terminal voltage. Period power approximation α · t ^β Is calculated.
[0105]
Generally, after completion of charging or discharging, a predetermined power approximate expression in which the exponent is negative is determined by a value obtained by subtracting the assumed open circuit voltage from the measured terminal voltage in each period, and this determination is performed. Until the exponent of the exponentiated approximate expression becomes -0.5, the determination of the exponentiated approximate expression is repeatedly executed by updating the assumed open circuit voltage, and the assumed open circuit voltage when the exponent becomes -0.5 May be estimated as the open circuit voltage.
[0106]
In addition, even if the assumed open circuit voltage is updated a predetermined number of times and repeatedly executed, if the exponent does not become −0.5 in some cases, the exponent becomes approximately −0 by executing the predetermined number of times. .5 is determined, the assumed open circuit voltage at this time is estimated as an open circuit voltage, and it is possible to eliminate the need to repeat the processing for determining the power approximation formula more than necessary.
[0107]
Now, in the case where the battery is charged from 0 to 100%, as described above, based on the terminal voltages measured at a constant period of 10 seconds from the end of the charging to the predetermined time Tb4 from the end of the charging, as described above, The assumed open circuit voltage is obtained by exponentially approximating the terminal voltage measured during the period, and the results are shown in Table 2.
[0108]
[Table 2]

[0109]
Table 2 also shows the difference from the assumed open circuit voltage in the adjacent period. For example, the assumed open circuit voltage in the period Ta2-Tb3 is 12.7655V, the assumed open circuit voltage in the left period Ta2-Tb2 of this period is 12.7600V, and the assumed open circuit voltage in the right period Ta2-Tb4. 7900 V, the assumed open circuit voltage of 12.7752 V in the upper period Ta1-Tb3, and the assumed open circuit voltage of 12.7885 V in the lower period Ta3-Tb3 are 0.0165, -0.0134, 0.0013, and-. It is shown to be 0.0113. It should be noted that, in Table 1, a period without adjacent periods in the vertical and horizontal directions is blank because a difference from an assumed open circuit voltage in the adjacent period cannot be seen.
[0110]
Comparing the difference between the assumed open circuit voltage of the adjacent period obtained for each period obtained as described above, the terminal voltage measured during the period Ta1-Tb3 (5 minutes to 60 minutes) is used. It can be seen that the difference between the assumed open circuit voltage obtained from the asymptotic root value asymptotically determined by the power approximation formula determined in the above and the adjacent period is the smallest. The assumed open circuit voltage based on the terminal voltage measured during this period Ta1-Tb3 (5 minutes to 60 minutes) is the terminal voltage measured at the time when 24 hours have elapsed after the battery has been charged, that is, the terminal voltage in the equilibrium state. The difference between the measured value of the open circuit voltage and 12.77425 V was very small, about 1 mV, and it was also confirmed that there was no supposed open circuit voltage having a smaller difference in other periods.
[0111]
Table 3 below shows a battery that is charged to 50% and is in a different situation from the case of Table 2, and from Table 2, unlike the case of Table 1, the period Ta4-Tb3 (35 Min-60 min), the assumed open-circuit voltage 12.3040 V obtained from the asymptotic value of the power approximation determined using the terminal voltage measured during the period of the terminal voltage measured during a period of time from the terminal voltage measured during the equilibrium state is 12.2969 V Is about 7 mV, which is smaller than about 27 mV in the period Ta1-Tb3 (5 minutes-60 minutes).
[0112]
[Table 3]

[0113]
In short, of the assumed open circuit voltages obtained in a plurality of predetermined periods, the period in which the difference between the assumed open circuit voltages in the adjacent periods is the smallest, specifically, the difference between the assumed open circuit voltage in the adjacent period and It can be understood that the open circuit voltage can be accurately estimated by using the assumed open circuit voltage in the period in which the value obtained by dividing the total sum of the absolute values by the number of adjacent periods as the open circuit voltage of the battery.
[0114]
Next, the battery open circuit voltage estimating process performed by the CPU 23a according to the control program stored in the ROM 23c will be described with reference to FIGS.
[0115]
It is assumed that the microcomputer 23 has been activated by receiving the power supply from the battery 13, and the microcomputer 23 determines whether the current value is 0 based on the current value obtained by sampling the output of the current sensor 15, for example. , It is determined whether the charging or discharging is completed. As a result of this determination, when the end of charging or discharging is detected, the open circuit voltage estimation processing shown in the flowchart of FIG. 9 is started. In this open circuit voltage estimation process, first, it is determined whether or not a predetermined time Ta1 of, for example, 5 minutes has elapsed from the end of charging or discharging (step S11).
[0116]
If the time has not elapsed, the process waits for the time to elapse, and if the time has elapsed (Y in step S11), the terminal voltage of the battery is then changed to the terminal voltage by the output of the voltage sensor 17 at regular intervals of, for example, 10 seconds. The voltage is measured and stored in a data area of the RAM 23b (corresponding to a terminal voltage collecting means) to collect the voltage (step S12). This sampling is continued until a predetermined time Tb4 of, for example, 80 minutes elapses from the end of charging or discharging (N in step S13).
[0117]
When the time Tb4 elapses (Y in step S13), a plurality of predetermined start points 5 minutes, 15 minutes, and 25 during a measurement period defined by the time 5 minutes to 80 minutes after the end of charge or discharge. One of the minutes and the thirty-fifth is selected to set Ta (step S14), and one of a plurality of predetermined end points 20, 20, 40, 60 and 80 is selected to set Tb. One of a plurality of periods is determined by combining the selected start point and end point (steps S14 and S15). After the period is determined, a process of calculating an assumed open circuit voltage in the period using the terminal voltage measured in the period is performed (step S16). This assumed open circuit voltage calculation process is performed until all the periods are completed. It is performed continuously (N in step S17).
[0118]
When the assumed open-circuit voltages for all the periods are calculated, the difference between the assumed open-circuit voltage for each period and the assumed open-circuit voltage for the adjacent period is calculated, and the difference is stored in the data area of the RAM 23b (corresponding to storage means). (Step S18). Then, a period in which the difference from the stored assumed open circuit voltage in the adjacent period is the smallest is selected, and the assumed open circuit voltage in the selected period is estimated as the open circuit voltage of the battery (step S19). The selection of the period in which the difference between the assumed open circuit voltages in the adjacent periods is the smallest is, specifically, a value obtained by dividing the sum of the absolute values of the differences between the assumed open circuit voltages in the adjacent periods by the number of the adjacent periods. This is done by selecting a period in which is minimized.
[0119]
Further, the assumed open circuit voltage calculation process in each period in step S16 in the flowchart of FIG. 9 described above is specifically performed as shown in the flowchart of FIG.
[0120]
First, the difference between the measured terminal voltage V (t) in each period and the assumed open circuit voltage E, that is, in the case of charging, the assumed open circuit voltage E from the measured terminal voltage V (t). In the case of the value after the subtraction and after the discharge, the absolute value of the value obtained by subtracting the assumed open circuit voltage E from the measured terminal voltage V (t) is obtained (step S16a), and the obtained value f (t) is approximated by a power. By performing the processing, a predetermined power approximate expression having a negative exponent is determined (step S16b).
[0121]
When the power approximate expression is determined, it is determined whether the power exponent β of the next determined power approximate expression is equal to -0.5 (step S16c). As a result of this determination, the exponent β becomes -0.5. If not (N in step S16c), the assumed open-circuit voltage E is updated (step S16d), and the updated assumed open-circuit voltage is returned to step S16a and the estimated open-circuit voltage is calculated from the measured terminal voltage V (t). The processing of subtracting the open circuit voltage E is performed. When the exponent β becomes -0.5 (Y in step S16c), the assumed open circuit voltage E when the exponent β becomes -0.5 is set as the assumed open circuit voltage in the period, and the data area of the RAM 23b is set. (Corresponding to a storage means) (step S16e) to end a series of processing operations, and return to the flowchart of FIG.
[0122]
Although not described in the flowchart of FIG. 10, when the power of the determined power approximate expression does not easily become −0.5, the voltage value at the time when the power approximate expression is determined a predetermined number of times is calculated. A series of processing operations can be ended by obtaining the assumed open circuit voltage E in the period. Also, similarly to the flowchart of FIG. 7, the charging state can be updated by the actually measured open circuit voltage.
[0123]
Further, in the flowchart of FIG. 10, the measurement is performed at a constant interval of 10 seconds from the time Ta1 to the time Tb4, but the microcomputer is put into the sleep state for a period other than the measurement every 10 seconds. You can also.
[0124]
The method of determining the power approximation expression in step S16b may be the same as that described above with reference to step S5 in the flowchart of FIG.
[0125]
Next, the method of updating the assumed open circuit voltage in step S16d may be the same as that described above with reference to FIG.
[0126]
Next, an open circuit voltage estimation operation (operation) of the present embodiment will be described. When the end of charging / discharging is detected from the output of the current sensor 15, the output of the voltage sensor 17 is taken in from the time when a certain time Ta1 has elapsed to the time Tb4, so that the terminal voltage of the battery is set as the terminal voltage. These voltage values are measured periodically, and the voltage values and the elapsed time from the end of charge / discharge are stored, stored, and collected in the data area of the RAM 23b.
[0127]
A plurality of predetermined periods are set for the collected terminal voltage, and the assumed open circuit voltage E is subtracted from the terminal voltage V (t) in each period, and the least square method is applied from the value obtained by the subtraction. To determine a power approximation formula. The determined cumulative approximation formula α · t ^β Is determined to be -0.5, and if the exponent β is not -0.5, the assumed open circuit voltage E is updated to a new one and the same processing is performed again. Power approximation α · t for each period ^β To determine. The above operation is repeated until the exponent β becomes -0.5 or approximately -0.5, and when either of them is established, the voltage value at that time is used as the assumed open circuit voltage for the period. Ask for it. It should be noted that the confirmation that the value has become approximately -0.5 can be performed when the number of determinations of the power approximation becomes a predetermined number or when the assumed open circuit voltage range becomes equal to or less than a predetermined range. .
[0128]
The assumed open circuit voltage for each period obtained as described above is calculated by the power approximation α · t ^β Therefore, the present invention can be applied as it is even if the characteristics of the battery are slightly different. In addition, if the charging / discharging current does not flow during the time from Ta1 to Tb4 from the end of charging / discharging, the open circuit voltage can be estimated each time, and the frequency at which the open circuit voltage can be estimated can be increased. .
[0129]
The present invention provides a vehicle, such as a hybrid car, in which a motor generator charges regenerative power to a battery, in order to appropriately know the state of charge of the battery and improve fuel efficiency by efficiently using the battery. Can be applied effectively.
[0130]
In this specification, a terminal voltage affected by polarization or the like is defined as a terminal voltage, and a terminal voltage in an equilibrium state is defined as an open circuit voltage.
[0131]
Further, in the present embodiment, in the example of Table 2, the measurement is performed up to 80 minutes after the end of the charging or discharging, but the resolution of the analog-digital conversion when reading the measured terminal voltage is about 5 mV. For up to 60 minutes, a measurement up to 60 minutes is sufficient and it is not necessary to measure up to 80 minutes.
[0132]
In the embodiment, Ta is set at an interval of 10 minutes, and Tb is set at an interval of 20 minutes. However, this interval can be set to be smaller than now. In general, although the accuracy is improved by the segmentation, the voltage difference between the adjacent periods is sufficiently small even at the above-described intervals, so that even if the segmentation is performed more than this, the number of operations increases and the burden increases. Many improvements in accuracy cannot be expected.
[0133]
Further, in the battery state-of-charge measuring device of the present embodiment, step S2 in the flowcharts of FIGS. 7 and 9 is a process for the voltage measuring means 23a-2 in claims, and steps S4 to S8 in FIG. Steps S16a to S16e of FIG. 10 are processing corresponding to the open-circuit voltage estimating means 23a-3 in the claims, and step S9 of FIG. 7 is processing corresponding to the calculating means 23a-4 in the claims. Step S10 in FIG. 7 is a process corresponding to the charged state updating means 23a-5 in the claims. It should be noted that the processing corresponding to the integrated charging state measuring means 23a-1 in the claims is not shown in the flowchart.
[0134]
【The invention's effect】
As described above, according to the invention as set forth in claim 1 or 16, after the charging or discharging of the battery is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value, the substantial charging is performed. Each time the discharge is completed, the current state of charge is updated using the state of charge of the battery calculated based on the open circuit voltage estimated based on the transition of the terminal voltage measured within a short period of time after the end of the discharge, and reset. The current state of charge is updated and set to an accurate value, and the error that may accumulate in the state of charge obtained by addition / subtraction based on the measured charging / discharging current by the current integration method before that. The battery charge state can be measured more accurately because the battery charge state is less likely to occur due to continuous accumulation of charge / discharge current over a long period of time. The measuring method and apparatus can be provided.
[0135]
According to the second aspect of the invention, after the charging or discharging of the battery is substantially completed, the assumed opening when the predetermined approximate expression is determined by the terminal voltage of the battery measured within a relatively short time. Since the circuit voltage can be estimated as an open circuit voltage, the state of charge of the battery can be more accurately measured based on the open circuit voltage of the vehicle battery which can be estimated within a relatively short time after the end of charging or discharging. A method can be provided.
[0136]
According to the third to fifth aspects of the present invention, the asymptote of the power approximation formula is set as the open circuit voltage by the terminal voltage of the battery measured within a relatively short time after the charging or discharging of the battery is substantially completed. Since it can be estimated, after charging or discharging of the battery is completed, by measuring the terminal voltage of the battery within a relatively short time, an asymptote of a power approximation formula can be obtained, and this can be estimated as an open circuit voltage. It is possible to provide a battery state-of-charge measuring method that can more accurately measure the state of charge of a battery based on the open-circuit voltage of the battery that can be estimated within a relatively short time from the end of charging or discharging.
[0137]
According to the invention described in claim 6, after the charging or discharging of the battery is substantially completed, the best one of the assumed open circuit voltages obtained from the battery terminal voltage measured within a relatively short time is opened. Since it can be estimated as the circuit voltage, it is possible to provide a battery state-of-charge measuring method that can more accurately measure the state of charge of the battery based on the open-circuit voltage.
[0138]
According to the invention as set forth in claim 7, within a predetermined time after the end of the charging or discharging, a plurality of different periods are provided comprehensively without omission, and an assumed open circuit voltage of each period is obtained. Since a good assumed open circuit voltage can be found, it is possible to provide a method of measuring the state of charge of a battery, which can use this to more accurately measure the state of charge of the battery of a vehicle.
[0139]
According to the invention of claim 8, it is not necessary to separately determine a period for measuring and collecting the terminal voltage, and it is not necessary to measure unnecessary terminal voltage that is not used. It is possible to provide a method of measuring the state of charge of a battery, which can reduce the burden of more accurate measurement of the state of charge.
[0140]
According to the ninth aspect of the present invention, it is not necessary to separately determine a period for measuring and collecting terminal voltages, and unnecessary terminal voltages that are not used need not be measured. And a method for measuring the state of charge of the battery.
[0141]
According to the tenth aspect of the present invention, since the open circuit voltage of the battery can be estimated after relative comparison regardless of the number of adjacent periods, the terminal voltage obtained during the measurement period can be effectively used without waste. It is possible to provide a method for estimating an open circuit voltage of a battery that can more accurately measure the state of charge of a battery of a vehicle by utilizing the method.
[0142]
According to the eleventh aspect of the present invention, after the charging or discharging of the battery is substantially completed, the assumed opening when the predetermined approximate expression is determined by the terminal voltage of the battery measured within a relatively short time. Since the circuit voltage can be estimated as an open circuit voltage, the state of charge of the battery can be more accurately measured based on the open circuit voltage of the vehicle battery which can be estimated within a relatively short time after the end of charging or discharging. A method can be provided.
[0143]
According to the invention as set forth in claims 12 to 14, after the charging or discharging of the battery is substantially completed, the asymptote of the power approximation formula is set as an open circuit voltage by the terminal voltage of the battery measured within a relatively short time. Since it can be estimated, after charging or discharging of the battery is completed, by measuring the terminal voltage of the battery within a relatively short time, an asymptote of a power approximation formula can be obtained, and this can be estimated as an open circuit voltage. It is possible to provide a battery state-of-charge measuring method that can more accurately measure the state of charge of a battery based on the open-circuit voltage of the battery that can be estimated within a relatively short time from the end of charging or discharging.
[0144]
According to the invention described in claims 15 and 17, the current state of charge is calculated using the state of charge calculated based on the actually measured open circuit voltage with higher accuracy than the state of charge calculated based on the estimated open circuit voltage. Since the state of charge of the battery can be updated, it is possible to provide a method and apparatus for measuring the state of charge of the battery, which can measure the state of charge more accurately than the method using only the estimated open circuit voltage.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of a battery open-circuit voltage estimation battery state-of-charge measuring device of the present invention.
FIG. 2 is a partial block diagram showing a schematic configuration of a battery open circuit voltage estimation battery charge state measuring device according to an embodiment of the present invention to which the battery open circuit voltage estimation battery charge state measurement method of the present invention is applied. FIG.
FIG. 3 is a graph showing a change in terminal voltage of a battery after charging is completed.
FIG. 4 is a graph used to explain an open circuit voltage estimation method.
FIG. 5 is another graph used to describe an open circuit voltage estimation method.
FIG. 6 is a graph for specifically illustrating the feasibility of the method of the present invention.
FIG. 7 is a flowchart showing a process performed by a microcomputer in FIG. 2 in accordance with a predetermined program for measuring a state of charge of a battery.
FIG. 8 is a graph used to explain how to update the assumed open circuit voltage.
FIG. 9 is a flowchart showing a process performed by a microcomputer in FIG. 2 according to a predetermined program for calculating an assumed open circuit voltage.
FIG. 10 is a flowchart showing a specific process of calculating an assumed open circuit voltage in FIG. 9;
[Explanation of symbols]
15 Current measuring means (current sensor)
23a-1 Integrating Charge State Measurement Means (CPU)
23a-2 Terminal voltage measuring means (CPU)
23a-3 Open circuit voltage estimation means (CPU)
23a-4 Calculation means (CPU)
23a-5 Charge state updating means (CPU)

Claims (17)

A charging current and a discharging current of a battery used by being mounted on a vehicle running with the engine as a power source are periodically measured, and the periodically measured charging current is added to a current charging state of the battery, and In a battery state-of-charge measuring method of measuring the state of charge of a battery by performing subtraction from the current state of charge of the battery of the periodically measured discharge current,
Measuring the terminal voltage of the battery,
After the charging or discharging of the battery is completed, or based on the transition of the measured terminal voltage after the current flowing to the battery has become a predetermined constant value or less, the open circuit voltage is estimated,
Calculating and calculating the state of charge of the battery based on the estimated open circuit voltage;
The battery state-of-charge measuring method, wherein the current state of charge is updated and set using the obtained state of charge. The measurement of the terminal voltage is performed after a predetermined time has elapsed after a predetermined time has elapsed after charging or discharging of the battery has been completed, or after a current flowing through the battery has become equal to or less than a predetermined constant value. Done several times in between,
The estimation of the open circuit voltage is based on the difference between the terminal voltage of the battery measured a plurality of times and the assumed open circuit voltage, and the transition of the terminal voltage is predicted to determine a predetermined approximate expression. Until the determined approximation formula is as predicted, or until the approximation is abbreviated as predicted, the approximation formula is repeatedly executed while updating the assumed open circuit voltage, and the approximation formula becomes as predicted. 2. The battery state-of-charge measuring method according to claim 1, wherein the method is performed by estimating the assumed open-circuit voltage when the voltage is approximated as predicted, as an open-circuit voltage. The determined approximate expression is a power approximate expression whose power is negative, and the power approximate is used until the power of the determined power approximate expression becomes -0.5 or approximately -0.5. Repeatedly determining the formula while updating the assumed open circuit voltage,
3. The battery state-of-charge measurement according to claim 2, wherein the assumed open circuit voltage when the exponent is -0.5 or substantially -0.5 is estimated as an open circuit voltage. Method. When the measured terminal voltage is falling, if the time is t, the unknown coefficient is α, and the unknown power is β, the power approximation formula is represented by α · t ^β. Item 3. The method for measuring the state of charge of a battery according to Item 3. When the measured terminal voltage is increasing, the value for determining the power approximation formula is an absolute value of a value obtained by subtracting the assumed open circuit voltage from the measured terminal voltage, and the time is t. the unknown coefficients alpha, When the number unknown to beta, battery state measuring method according to claim 3, characterized in that the power approximate formula of α · t ^β. The measurement of the terminal voltage is performed at a predetermined cycle and collected,
Estimating the open circuit voltage,
A voltage value asymptotic to a predetermined approximate expression based on the terminal voltage in each of a plurality of predetermined periods with respect to the collected terminal voltage is obtained as an assumed open circuit voltage in each period. ,
2. The battery state-of-charge measurement method according to claim 1, wherein the method is performed by estimating the assumed open-circuit voltage in a period in which a difference between the assumed open-circuit voltage in an adjacent period and the assumed open-circuit voltage is minimized as an open-circuit voltage. Each of the plurality of periods, after completion of charging or discharging, or one of a plurality of predetermined starting points and a plurality of endings according to a time after a current flowing through the battery becomes a predetermined constant value or less. 7. The method for measuring the state of charge of a battery according to claim 6, wherein the method is determined by a combination with one of the points. The method according to claim 7, wherein the shortest start point and the longest end point correspond to the start and end of a period for measuring and collecting the terminal voltage. 9. The method according to claim 7, wherein an interval between the plurality of start points is smaller than an interval between the plurality of end points. A period in which the value obtained by dividing the sum of absolute values of the difference between the assumed open circuit voltage and the assumed open circuit voltage in the adjacent period by the number of the adjacent periods is the smallest, the difference between the assumed open circuit voltage in the adjacent period and the assumed open circuit voltage is the smallest. The battery state-of-charge measuring method according to claim 6, wherein the period is a period. When the collected terminal voltage is falling, a predetermined exponential approximation in which the exponent is negative is determined by the difference between the terminal voltage in each period and the assumed open circuit voltage, and the determination is made. By repeatedly executing the determination of the power-approximation equation while updating the assumed open-circuit voltage until the exponent of the power-approximation equation becomes -0.5 or approximately -0.5, The battery state-of-charge measuring method according to any one of claims 6 to 10, wherein a voltage value for which the power approximation formula asymptotically is obtained. When the collected terminal voltage rises, a predetermined power approximate expression in which the exponent is negative is determined by the absolute value of the value obtained by subtracting the assumed open circuit voltage from the terminal voltage in each period. Repeating the determination of the power approximate expression while updating the assumed open circuit voltage until the power of the determined power approximate expression becomes −0.5 or becomes approximately −0.5. The method for measuring the state of charge of a battery according to any one of claims 6 to 10, wherein a voltage value at which the power approximation formula asymptotically is obtained. 13. The battery state of charge according to claim 11, wherein the time approximation expression is represented by α · t ^β, where t is time, an unknown coefficient is α, and an unknown negative exponent is ^β. Measuring method. 14. The battery according to claim 4, wherein the terminal voltage is an arbitrary number of 2 or more, and the arbitrary number of terminal voltages is subjected to regression calculation processing to determine a power number β of the power approximate expression. Charge state measurement method. After the charging or discharging of the battery is completed, or after the current flowing in the battery has become equal to or less than a predetermined constant value, the battery is in the state continuously for a predetermined time during which the terminal voltage of the battery is stabilized. Measuring the open circuit voltage by measuring the terminal voltage of the battery,
Calculating and calculating the state of charge of the battery based on the measured open circuit voltage;
15. The method according to claim 1, wherein the current state of charge is updated and set using the obtained state of charge. Current measuring means for periodically measuring a charging current and a discharging current of a battery mounted and used on a vehicle running with an engine as a power source; and the battery of the charging current periodically measured by the current measuring means Integrating charge state measuring means for measuring the state of charge of the battery by performing addition to the current state of charge and subtraction of the discharge current periodically measured by the current measuring means from the current state of charge of the battery, respectively. In a battery state-of-charge measuring device comprising:
Voltage measuring means for measuring a terminal voltage of the battery,
After charging or discharging is completed, or an open circuit voltage estimating means for estimating an open circuit voltage based on a transition of the measured terminal voltage after a current flowing through the battery becomes equal to or less than a predetermined constant value,
Calculating means for calculating the state of charge of the battery based on the open circuit voltage estimated by the open circuit estimating means;
A battery state-of-charge measuring device comprising: a state-of-charge updating unit that updates and sets the current state of charge using the state of charge obtained by the arithmetic unit. The voltage measuring unit is configured to continuously charge the battery for a predetermined time after the charging or discharging of the battery is completed, or after the current flowing through the battery becomes equal to or less than a predetermined constant value. When in this state, measure the terminal voltage of the battery,
The calculating means calculates and calculates the state of charge of the battery using the measured terminal voltage as an actually measured open circuit voltage,
17. The battery state-of-charge measuring device according to claim 16, wherein the state-of-charge updating means updates and sets the current state of charge using a state of charge obtained based on the actually measured open circuit voltage.

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