JP3936542B2 - Battery capacity calculation method and apparatus - Google Patents

Description

となる。
【００３１】
【発明が解決しようとする課題】
ところで、バッテリの放電中には、図１８に示すように、純抵抗（バッテリのオーミック抵抗）の影響による電圧降下、つまり、純抵抗に放電電流を乗じたＩＲ降下や、放電側分極による電圧降下が生じ、逆に、バッテリの充電中には、これら純抵抗の影響による電圧上昇や充電側分極による電圧上昇が生じる。
【００３２】
特に、図１８に示すように、バッテリの放電時に生じる放電側分極に含まれる、電極の表面上で酸化還元反応を進行させるための活性化分極や、物質移動の結果として電極表面と溶液バルクとの間に生じた反応物や生成物の濃度差による濃度分極は、放電電流の増減に対して多少遅れて反応するため、放電電流の値に比例するような直線的相関を示さない。
【００３３】
そのため、上述したように、バッテリの充電状態ＳＯＣを求めるために、放電時に測定できないバッテリの開回路電圧に代わって推定電圧Ｖｎを求める場合、その前段階として、端子電圧と放電電流とを放電中に測定してバッテリの電圧−電流特性を求めると、その端子電圧が放電時の分極による電圧降下を含んでいることから、求めたバッテリの電圧−電流特性やその電圧−電流特性から推定した推定電圧Ｖｎが、バッテリの充電状態ＳＯＣだけでなく分極による電圧降下を反映したものとなってしまい、よって、この推定電圧Ｖｎをそのまま用いたのでは、バッテリの充電状態ＳＯＣを正確に求めることができない。
【００３４】
本発明は前記事情に鑑みなされたもので、本発明の目的は、放電時に測定できるバッテリの端子電圧と放電電流との相関から求められる、バッテリの定負荷放電状態における推定上の端子電圧である推定電圧を用いて、バッテリの充電状態を求めるに当たり、推定電圧を求めるのに用いた放電中のバッテリの端子電圧が、前回の充電や放電による電圧上昇や電圧降下の完全に解消していないものである場合であっても、バッテリの充電状態を正確に演算することのできるバッテリ容量演算方法と、この方法を実施する際に用いて好適なバッテリ容量演算装置とを提供することにある。
【００３５】
【課題を解決するための手段】
前記目的を達成する請求項１乃至請求項６記載の本発明は、バッテリ容量演算方法に関するものであり、請求項７乃至請求項１２記載の本発明は、バッテリ容量演算装置に関するものである。
【００３６】
そして、請求項１に記載した本発明のバッテリ容量演算方法は車両の負荷に電力を供給するバッテリの端子電圧と放電電流とを周期的に測定してこれら端子電圧と放電電流との相関を示す電圧−電流特性を求め、この電圧−電流特性を用いて前記バッテリの定負荷放電状態における推定上の端子電圧である推定電圧を推定し、この推定電圧を用いて前記バッテリの充電容量を演算するに当たり、各種の充電容量におけるバッテリの電圧―電流特性を表わす式に基づいて、前記充電容量の変化に対応して直線的に変化する電圧を与える電流の値を仮想電流値として、あらかじめ、求めておき、平衡状態の前記バッテリによる定負荷放電の放電電流が、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値から減少している間の、電圧−電流特性を表わす式において、各種の充電容量におけるバッテリの電圧―電流特性を表わす式に基づいてあらかじめ求めておいた、前記充電容量の変化に対応して直線的に変化する電圧である推定電圧を与える電流を仮想電流値として代入して、推定した、前記所定の大電流値による定負荷放電時における前記バッテリの推定電圧の値と、該推定電圧の値を推定するのに用いた前記定負荷放電の開始前における平衡状態の前記バッテリの端子電圧である開回路電圧の値との差値を、前記バッテリの放電終了時における残存分極の影響による残存電圧降下量である残存電圧降下値として予め求めておき、以後、前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行う毎に、該定負荷放電中に周期的に測定した前記バッテリの端子電圧と放電電流とから電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に前記仮想電流値を代入して前記バッテリの現在の推定電圧を推定し、前記推定した前記バッテリの現在の推定電圧の値に、前記残存電圧降下値を加算することで、前記バッテリの現在の充電容量を演算するようにした、ことを特徴とする。
【００３７】
また、請求項２に記載した本発明のバッテリ容量演算方法は、請求項１に記載した本発明のバッテリ容量演算方法において、平衡状態の前記バッテリの端子電圧の値を予め測定して該測定値を前記開回路電圧の値に設定しておき、該開回路電圧の設定に続いて、平衡状態の前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値にる定負荷放電を行った際、該定負荷放電の放電電流が最大電流値から減少する間に周期的に測定した、前記バッテリの端子電圧と放電電流とから、電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に前記仮想電流値を代入して、平衡状態からの、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧を推定し、該推定した、前記バッテリの推定電圧の値を、前記設定した前記開回路電圧の値から差し引くことで、前記残存電圧降下値を予め求めておくようにしたことを特徴とする。
【００３８】
さらに、請求項３に記載した本発明のバッテリ容量演算方法は、請求項２に記載した本発明のバッテリ容量演算方法において、前記バッテリが平衡状態となる毎に、前記開回路電圧の値を、当該平衡状態において測定した前記バッテリの端子電圧の値に更新設定するようにした。
【００３９】
また、請求項４に記載した本発明のバッテリ容量演算方法は、請求項１，２又は３に記載した本発明のバッテリ容量演算方法において、前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行う毎に、該定負荷放電の放電電流が最大電流値から減少する間に周期的に測定した、前記バッテリの端子電圧と放電電流とから、電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に仮想電流値を代入して、前記バッテリの現在の推定電圧の推定を行うようにした。
【００４０】
さらに、請求項５に記載した本発明のバッテリ容量演算方法は、請求項１、２、３又は４に記載した本発明のバッテリ容量演算方法において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値を、前記車両のセルモータ始動時に必要とする所定の大電流値とし、前記バッテリの放電電流値が、前記所定の大電流値から減少し始めてから、該所定の大電流値よりも低く、かつ、前記セルモータ以外の前記車両の負荷が駆動されている際における最大放電電流値以上の、目標電流値に低下するまでの間に、周期的に測定した前記バッテリの端子電圧と放電電流とから、前記所定の大電流値による定負荷放電時における前記バッテリの推定電圧を推定するのに用いる電圧−電流特性を表わす式を求めるようにした。
【００４１】
また、請求項６に記載した本発明のバッテリ容量演算方法は、請求項１、２、３、４又は５に記載した本発明のバッテリ容量演算方法において、少なくとも放電直前に前記バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧を推定する毎に、該推定時点における前記バッテリの周辺温度と、前記開回路電圧を求めた時点における前記バッテリの周辺温度との差の有無を確認し、差がある場合は、その温度差に応じて、前記残存電圧降下値を補正し、該補正した残存電圧降下値を用いて前記バッテリの現在の充電容量を演算するようにした。
【００４２】
さらに、請求項７に記載した本発明のバッテリ容量演算装置は、図１の基本構成図に示すように、車両の負荷に電力を供給するバッテリ１３の、少なくとも放電直前に該バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時に、この定負荷放電時におけるバッテリ１３の端子電圧と放電電流とを周期的に測定してこれら端子電圧と放電電流との相関を示す電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式を用いて前記バッテリ１３の定負荷放電状態における推定上の端子電圧である推定電圧を推定し、この推定電圧を用いて前記バッテリ１３の充電容量を演算するバッテリ１３容量演算装置において、平衡状態の前記バッテリ１３による定負荷放電の放電電流が、少なくとも放電直前に該バッテリ１３に発生していた充電側分極を解消するのに十分な電流値から減少している間の、前記電圧−電流特性を表わす式において各種の充電容量におけるバッテリ１３の電圧―電流特性を表わす式に基づいてあらかじめ求めらておいた、前記充電容量の変化に対して直線的に変化する電圧である推定電圧を与える電流を、仮想電流値として代入して、推定した、少なくとも放電直前に該バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリ１３の推定電圧の値と、該推定電圧の値を推定するのに用いた前記定負荷放電の開始前における平衡状態の前記バッテリ１３の端子電圧である開回路電圧の値との差値を、前記バッテリ１３の放電終了時における残存分極の影響による残存電圧降下量である残存電圧降下値として記憶する残存電圧降下値記憶手段２７を備えており、前記残存電圧降下値記憶手段に記憶された前記残存電圧降下値を、前記推定した前記バッテリ１３の推定電圧の値に加算することで、前記バッテリ１３の現在の充電容量を演算するものとした。
【００４３】
また、請求項８に記載した本発明のバッテリ容量演算装置は、請求項７に記載した本発明のバッテリ容量演算装置において、少なくとも放電直前に前記バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による前記バッテリ１３の定負荷放電において、該バッテリ１３の放電電流が最大電流値から減少し始めたことを検出する放電電流減少開始検出手段Ａと、前記バッテリ１３の放電電流が最大電流値から減少し始めたことを前記放電電流減少開始検出手段Ａが検出した後に、周期的に測定される前記バッテリ１３の端子電圧と放電電流とから前記電圧−電流特性を表わす式を求める特性割出手段２３Ａと、該特性割出手段２３Ａが求めた前記電圧−電流特性を表わす式を用いて、少なくとも放電直前に前記バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリ１３の推定電圧を推定する推定電圧推定手段２３Ｂとをさらに備えており、該推定電圧推定手段２３Ｂが推定した前記バッテリ１３の推定電圧の値に、前記残存電圧降下値記憶手段２７に記憶された前記残存電圧降下値を加算することで、前記バッテリ１３の現在の充電容量を演算するものとした。
【００４４】
さらに、請求項９に記載した本発明のバッテリ容量演算装置は、請求項８に記載した本発明のバッテリ容量演算装置において、前記開回路電圧の値を記憶する開回路電圧値記憶手段２５と、前記バッテリ１３が平衡状態にあるか否かを判別する平衡状態判別手段２３Ｃと、該平衡状態判別手段２３Ｃにより平衡状態にあると判別された前記バッテリ１３からの、少なくとも放電直前に該バッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時に、前記推定電圧推定手段２３Ｂが推定した前記バッテリ１３の推定電圧の値を、前記開回路電圧値記憶手段２５に記憶された前記開回路電圧の値から差し引いて前記残存電圧降下値を求める残存電圧降下値割出手段２３Ｄとをさらに備えており、前記残存電圧降下値記憶手段２７が、前記残存電圧降下値割出手段２３Ｄが求めた前記残存電圧降下値を記憶するものとした。
【００４５】
また、請求項１０に記載した本発明のバッテリ容量演算装置は、請求項９に記載した本発明のバッテリ容量演算装置において、前記平衡状態判別手段２３Ｃにより平衡状態にあると判別された状態において前記バッテリ１３の端子電圧を測定する平衡状態端子電圧測定手段Ｂと、前記開回路電圧値記憶手段２５に記憶された前記開回路電圧の値を、前記平衡状態端子電圧測定手段Ｂが測定した前記バッテリ１３の端子電圧の値に更新する開回路電圧更新手段２３Ｅとをさらに備えているものとした。
【００４６】
さらに、請求項１１に記載した本発明のバッテリ容量演算装置は、請求項１０に記載した本発明のバッテリ容量演算装置において、前記バッテリ１３の周辺温度を検出する温度検出手段１９と、前記バッテリ１３の推定電圧を前記推定電圧推定手段２３Ｂが推定した時点において、前記温度検出手段１９が検出した前記バッテリ１３の周辺温度と、前記バッテリ１３の端子電圧を前記平衡状態端子電圧測定手段Ｂが測定した時点において、前記温度検出手段１９が検出した前記バッテリ１３の周辺温度との差の有無を確認し、差がある場合は、その温度差に応じて、前記残存電圧降下値記憶手段２７に記憶された前記残存電圧降下値を補正する補正手段２３Ｆとをさらに備えており、該補正手段２３Ｆにより前記残存電圧降下値が補正された場合は、補正後の前記残存電圧降下値を、前記推定電圧推定手段２３Ｂが推定した前記バッテリ１３の推定電圧の値に加算することで、前記バッテリ１３の現在の充電容量を演算するものとした。
【００４７】
また、請求項１２に記載した本発明のバッテリ容量演算装置は、請求項８、９、１０又は１１に記載した本発明のバッテリ容量演算装置において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値は、前記車両のセルモータ始動時に必要とする所定の大電流値であり、前記放電電流減少開始検出手段は、前記バッテリの定負荷放電において、該バッテリの放電電流が前記所定の大電流値から減少し始めたことを検出するように構成されており、該所定の大電流値から減少し始めたことを前記放電電流減少開始検出手段が検出した前記バッテリの放電電流が、前記セルモータ以外の前記車両の負荷が駆動されている際における最大放電電流値以上の、目標電流値に低下したことを検出する放電電流低下検出手段をさらに備えており、前記特性割出手段は、前記バッテリの放電電流が前記所定の大電流値から減少し始めたことを前記放電電流減少開始検出手段が検出した後、前記目標電流値に低下したことを前記放電電流低下検出手段が検出するまでの間、前記周期的に測定される前記バッテリの端子電圧と放電電流とから前記電圧−電流特性を表わす式を求めるものとした
【００４８】
請求項１に記載した本発明のバッテリ容量演算方法によれば、バッテリが行う定負荷放電の放電電流が、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値に達すると、前回の放電において発生した放電側や充電側の分極による電圧降下や電圧上昇が仮に放電開始前に残存していても、その残存する電圧降下を上回る、放電電流値に応じた大きさの放電側分極が発生した状態となり、或は、その残存する電圧上昇が解消した上で、放電電流値に応じた大きさの放電側分極が新たに発生した状態となる。
【００４９】
一方、平衡状態にあるバッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行っても、その放電電流値に達すると、その放電電流値に応じた大きさの放電側分極が発生した状態となる。
【００５０】
したがって、バッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、その定負荷放電の開始前にバッテリが平衡状態にあったか、それとも、前回の放電において発生した放電側や充電側の分極状態が完全には解消しきれていない状態にあったかに拘わらず、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値から放電電流が減少している間のバッテリの端子電圧と放電電流とから求めた電圧−電流特性を表わす式により推定されるバッテリの推定電圧は、同じ値となる。
【００５１】
そして、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電の開始前にバッテリが平衡状態にあったか否かに拘わらず、その定負荷放電をバッテリが開始した後に推定される推定電圧の値は、定負荷放電を開始する前のバッテリが平衡状態にあったと仮定した場合の、その平衡状態におけるバッテリの端子電圧に当たる開回路電圧に対して、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値によってバッテリが行った定負荷放電の終了時における残存分極の影響による残存電圧降下量として予め求められている残存電圧降下値の分だけ、低い値を示すことになる。
【００５２】
また、請求項２に記載した本発明のバッテリ容量演算方法によれば、請求項１に記載した本発明のバッテリ容量演算方法において、平衡状態のバッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、まず、定負荷放電の開始前にバッテリの端子電圧の値を測定することで開回路電圧の値が設定され、続いて、定負荷放電の放電電流値が、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値から減少すると、周期的に測定したバッテリの端子電圧と放電電流とから求めた電圧−電流特性を表わす式に仮想電流値を代入して推定電圧が推定されて、この推定電圧の値と、先に設定された開回路電圧の値との差分が、残存電圧降下値として求められて、以後、バッテリの現在の充電容量を演算するために行われる、バッテリが定負荷放電を行う毎に推定されるバッテリの現在の推定電圧への加算に供されることになる。
【００５３】
さらに、請求項３に記載した本発明のバッテリ容量演算方法によれば、請求項２に記載した本発明のバッテリ容量演算方法において、放電に伴う充電状態の変化に応じて変化するバッテリの開回路電圧が、バッテリが平衡状態となる度に、最新の端子電圧の値に更新設定されることになる。
【００５４】
また、請求項４に記載した本発明のバッテリ容量演算方法によれば、請求項１、２又は３に記載した本発明のバッテリ容量演算方法において、バッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、その度に、放電電流値が最大電流値から減少する間に周期的に測定したバッテリの端子電圧と放電電流とから求めた電圧−電流特性を表わす式に仮想電流値を代入して、バッテリの現在の推定電圧が推定され、この推定電圧の値と残存電圧降下値とから、バッテリの現在の充電状態が演算されることになる。
【００５５】
さらに、請求項５に記載した本発明のバッテリ容量演算方法によれば、請求項１、２、３又は４に記載した本発明のバッテリ容量演算方法において、車両のセルモータ始動時に必要とする所定の大電流値は、その車両の他の負荷に対してバッテリからの電力が仮に複数同時に供給されている場合であっても、その場合の電流値を上回ることから、このセルモータ始動時に必要とする所定の大電流値を、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値とすることで、放電電流が所定の大電流値に達した際に、前回の放電によって発生した放電側分極による電圧降下を上回る電圧降下がバッテリの端子電圧に発生した状態に至る。
【００５６】
一方、バッテリの放電電流値が所定の大電流値から減少して、セルモータ以外の車両の負荷が駆動されている際における最大放電電流値以上の目標電流値に低下すると、その状態でバッテリの端子電圧に残存している放電側分極による電圧降下には、セルモータ以外の車両の負荷に電力を供給することで発生した放電側分極による電圧降下成分は表面上現れず、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下の、放電電流が目標電流値に低下したことにより解消した分を除く残存成分のみが、表面上現れた状態となる。
【００５７】
したがって、所定の大電流値による定負荷放電を行ったバッテリの放電電流値が、所定の大電流値から減少して目標電流値に低下するまでの間に、周期的に測定した端子電圧と放電電流とから、バッテリの電圧−電流特性を表わす式を求めると、この電圧−電流特性を表わす式に仮想電流値を代入して推定した推定電圧は、セルモータ以外の車両の負荷が今なお駆動されているとしても、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下の、放電電流が目標電流値に低下したことにより解消した分を除く残存成分のみを、純粋に反映したものになることになる。
【００５８】
また、請求項６に記載した本発明のバッテリ容量演算方法によれば、請求項１、２、３、４又は５に記載した本発明のバッテリ容量演算方法において、バッテリの周辺温度が変化すると、バッテリの容量が変化してバッテリの端子に現れる端子電圧も変化するので、平衡状態のバッテリの開回路電圧を求めた時点と、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時におけるバッテリの推定電圧の推定時点とで、バッテリの周辺温度が異なると、バッテリの周辺温度に応じて開回路電圧に反映されている端子電圧成分と、バッテリの周辺温度に応じて推定電圧に反映されている端子電圧成分とが、各々相違することになる。
【００５９】
しかし、平衡状態のバッテリの開回路電圧を求めた時点におけるバッテリの周辺温度と、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時におけるバッテリの推定電圧の推定時点におけるバッテリの周辺温度とに応じて補正した、補正後の残存電圧降下値を用いて、バッテリの現在の充電容量を演算すると、バッテリの周辺温度に応じた端子電圧成分が同じ条件で反映された開回路電圧と推定電圧とを用いて、バッテリの周辺温度の相違による端子電圧の変動成分が排除された状態で、バッテリの現在の充電状態が演算されることになる。
【００６０】
さらに、請求項７に記載した本発明のバッテリ容量演算装置によれば、図１に示すように、バッテリ１３が行う定負荷放電の放電電流が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値に達すると、前回の放電において発生した放電側や充電側の分極による電圧降下や電圧上昇が仮に放電開始前に残存していても、その残存する電圧降下を上回る、放電電流値に応じた大きさの放電側分極が発生した状態となり、或は、その残存する電圧上昇が解消した上で、放電電流値に応じた大きさの放電側分極が新たに発生した状態となる。
【００６１】
一方、平衡状態にあるバッテリ１３が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行っても、その放電電流値に達すると、その放電電流値に応じた大きさの放電側分極が発生した状態となる。
【００６２】
したがって、バッテリ１３が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、その定負荷放電の開始前にバッテリ１３が平衡状態にあったか、それとも、前回の放電において発生した放電側や充電側の分極状態が完全には解消しきれていない状態にあったかに拘わらず、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値から放電電流が減少している間のバッテリ１３の端子電圧と放電電流とから求めた電圧−電流特性を表わす式により推定されるバッテリ１３の推定電圧は、同じ値となる。
【００６３】
そして、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電の開始前にバッテリ１３が平衡状態にあったか否かに拘わらず、その定負荷放電をバッテリ１３が開始した後に推定される推定電圧の値は、定負荷放電を開始する前のバッテリ１３が平衡状態にあったと仮定した場合の、その平衡状態におけるバッテリ１３の端子電圧に当たる開回路電圧に対して、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値によってバッテリ１３が行った定負荷放電の終了時における残存分極の影響による残存電圧降下量として予め求められて、残存電圧降下値記憶手段２７に記憶されている、残存電圧降下値の分だけ、低い値を示すことになる。
【００６４】
また、請求項８に記載した本発明のバッテリ容量演算装置によれば、請求項７に記載した本発明のバッテリ容量演算装置において、バッテリ１３が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、バッテリ１３の放電電流が最大電流値から減少し始めたことを放電電流減少開始検出手段Ａが検出する度に、放電電流値が最大電流値から減少する間に周期的に測定したバッテリ１３の端子電圧と放電電流とから電圧−電流特性を表わす式が特性割出手段２３Ａにより求められ、この特性割出手段２３Ａにより求められた電圧−電流特性を表わす式に仮想電流値を代入して、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電時におけるバッテリ１３の推定電圧が推定電圧推定手段２３Ｂにより推定され、この推定電圧推定手段２３Ｂにより推定された推定電圧の値と、残存電圧降下値記憶手段２７に記憶されている残存電圧降下値とから、バッテリ１３の現在の充電状態が演算されることになる。
【００６５】
さらに、請求項９に記載した本発明のバッテリ容量演算装置によれば、請求項８に記載した本発明のバッテリ容量演算装置において、平衡状態判別手段２３Ｃにより平衡状態にあると判別されたバッテリ１３が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行うと、残存電圧降下値割出手段２３Ｄによって、バッテリ１３の放電電流が最大電流値から減少し始めたことが放電電流減少開始検出手段Ａにより検出された後に推定電圧推定手段２３Ｂにより推定された推定電圧の値が、開回路電圧値記憶手段２５に記憶された開回路電圧の値から差し引かれて、残存電圧降下値が求められ、この求められた残存電圧降下値が残存電圧降下値記憶手段２７に記憶されることになる。
【００６６】
また、請求項１０に記載した本発明のバッテリ容量演算装置によれば、請求項９に記載した本発明のバッテリ容量演算装置において、放電に伴う充電状態の変化に応じてバッテリ１３の開回路電圧が変化しても、バッテリ１３が平衡状態にあると平衡状態判別手段２３Ｃにより判別される毎に、開回路電圧値記憶手段２５に記憶された開回路電圧の値が、平衡状態端子電圧測定手段Ｂにより測定された平衡状態のバッテリ１３の端子電圧の最新値に更新されることになる。
【００６７】
さらに、請求項１１に記載した本発明のバッテリ容量演算装置によれば、請求項１０に記載した本発明のバッテリ容量演算装置において、バッテリ１３の周辺温度が変化すると、バッテリ１３の容量が変化してバッテリ１３の端子に現れる端子電圧も変化するので、開回路電圧値記憶手段２５に記憶させた開回路電圧を求めた時点と、平衡状態判別手段２３Ｃにより平衡状態にあると判別されたバッテリ１３の放電電流が所定の大電流値から減少し始めたことを放電電流減少開始検出手段Ａが検出した後に、バッテリ１３の推定電圧を推定電圧推定手段２３Ｂが推定した時点とで、温度検出手段１９により検出されたバッテリ１３の周辺温度が異なると、バッテリ１３の周辺温度に応じて開回路電圧に反映されている端子電圧成分と、バッテリ１３の周辺温度に応じて推定電圧に反映されている端子電圧成分とが、各々相違することになる。
【００６８】
しかし、開回路電圧値記憶手段２５に記憶させた開回路電圧を求めた時点で温度検出手段１９により検出されたバッテリ１３の周辺温度と、平衡状態判別手段２３Ｃにより平衡状態にあると判別されたバッテリ１３の放電電流が、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値から減少し始めたことを放電電流減少開始検出手段Ａが検出した後に、バッテリ１３の推定電圧を推定電圧推定手段２３Ｂが推定した時点で、温度検出手段１９により検出されたバッテリ１３の周辺温度とが、互いに異なっていても、残存電圧降下値記憶手段２７に記憶された残存電圧降下値を両周辺温度に応じて補正手段２３Ｆにより補正して、この補正手段２３Ｆにより補正された後の残存電圧降下値を用いてバッテリ１３の現在の充電容量を演算することで、バッテリ１３の周辺温度に応じた端子電圧成分が同じ条件で反映された開回路電圧と推定電圧とを用いて、バッテリ１３の周辺温度の相違による端子電圧の変動成分が排除された状態で、バッテリ１３の現在の充電状態が演算されることになる。
【００６９】
また、請求項１２に記載した本発明のバッテリ容量演算装置によれば、請求項８、９、１０又は１１に記載した本発明のバッテリ容量演算装置において、車両のセルモータ５始動時に必要とする所定の大電流値は、その車両の他の負荷に対してバッテリ１３からの電力が仮に複数同時に供給されている場合であっても、その場合の電流値を上回ることから、このセルモータ５始動時に必要とする所定の大電流値を、少なくとも放電直前にバッテリ１３に発生していた充電側分極をするのに十分な電流値とすることで、バッテリ１３による定負荷放電の放電電流が最大電流値から減少し始めたことを放電電流減少開始検出手段Ａが検出した時点では、それ以前に放電電流が所定の大電流値に一旦達して、前回の放電によって発生した放電側分極による電圧降下を上回る電圧降下がバッテリ１３の端子電圧に発生した状態に至っていることになる。
【００７０】
そして、バッテリ１３の放電電流値が所定の大電流値から減少して、セルモータ５以外の車両の負荷が駆動されている際における最大放電電流値以上の目標電流値に低下したことを放電電流低下検出手段Ｃが検出した時点では、その状態でバッテリ１３の端子電圧に残存している放電側分極による電圧降下には、セルモータ５以外の車両の負荷に電力を供給することで発生した放電側分極による電圧降下成分は表面上現れず、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下の、放電電流が目標電流値に低下したことにより解消した分を除く残存成分のみが、表面上現れた状態に至っていることになる。
【００７１】
したがって、バッテリ１３の放電電流が所定の大電流値から減少し始めたことを放電電流減少開始検出手段Ａが検出した後、目標電流値に低下したことを放電電流低下検出手段Ｃが検出するまでの間に、周期的に測定した端子電圧と放電電流とから特性割出手段２３Ａがバッテリ１３の電圧−電流特性を表わす式を求めると、この電圧−電流特性を表わす式に仮想電流値を代入して推定電圧推定手段２３Ｂが推定した推定電圧は、セルモータ５以外の車両の負荷が今なお駆動されているとしても、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下の、放電電流が目標電流値に低下したことにより解消した分を除く残存成分のみを、純粋に反映したものになることになる。
【００７２】
【発明の実施の形態】
以下、本発明によるバッテリ容量演算方法を、本発明によるバッテリ容量演算装置と共に、図面を参照して説明する。
【００７３】
図２は本発明のバッテリ容量演算方法を適用した本発明の一実施形態に係るバッテリ容量演算装置の概略構成を一部ブロックにて示す説明図であり、図２中引用符号１で示す本実施形態のバッテリ容量演算装置は、エンジン３に加えてモータジェネレータ５を有するハイブリッド車両に搭載されている。
【００７４】
そして、このハイブリッド車両は、通常時はエンジン３の出力のみをドライブシャフト７からディファレンシャルケース９を介して車輪１１に伝達して走行させ、高負荷時には、バッテリ１３からの電力によりモータジェネレータ５をモータとして機能させて、エンジン３の出力に加えてモータジェネレータ５の出力をドライブシャフト７から車輪１１に伝達し、アシスト走行を行わせるように構成されている。
【００７５】
また、このハイブリッド車両は、減速時や制動時にモータジェネレータ５をジェネレータ（発電機）として機能させ、運動エネルギを電気エネルギに変換してバッテリ１３を充電させるように構成されている。
【００７６】
尚、モータジェネレータ５はさらに、不図示のスタータスイッチのオンに伴うエンジン３の始動時に、エンジン３のフライホイールを強制的に回転させるセルモータとして用いられるが、その場合にモータジェネレータ５は、このハイブリッド車両に搭載された他の電動負荷が同時に複数動作している状態よりも多くの電力を単独で消費する。
【００７７】
ちなみに、本実施形態のハイブリッド車両においては、スタータスイッチはオフであるものの、不図示のアクセサリスイッチやイグニッションスイッチとか、モータジェネレータ５以外の電装品（負荷）のスイッチ（図示せず。）がオンであるために、エアコン、オーディオ機器、パワーウィンド、ヘッドライト、並びに、ルームランプ（いずれも図示せず。）等が作動している場合、バッテリ１３から流れる放電電流は、それらの電装品が同時に複数作動していても３５Ａ（アンペア）に満たない。
【００７８】
逆に、アクセサリスイッチがオンされ、その上でスタータスイッチがオンされて、エンジン３を始動させるためにモータジェネレータ５をセルモータとして作動させる際には、例え他の電装品が何も作動していなくても、およそ２５０Ａ（アンペア）に達する放電電流がバッテリ９から瞬時的に流れる。
【００７９】
したがって、本実施形態のバッテリ容量演算装置１においては、バッテリ１３の放電電流が目標電流値＝３５Ａ（下限）から最大電流値＝２５０Ａ（上限）までの間にあるかどうかが、モータジェネレータ５をセルモータとして作動させるための定負荷放電が行われていることを見分けるための目安となる。
【００８０】
尚、スタータスイッチのオンによりモータジェネレータ５によってエンジン３が始動されると、イグニッションキー（図示せず。）の操作解除に伴って、スタータスイッチがオフになってイグニッションスイッチやアクセサリスイッチのオン状態に移行する。
【００８１】
話を構成の説明に戻して、本実施形態のバッテリ容量演算装置１は、上述したバッテリ１３の充電状態を演算するもので、アシスト走行用のモータやセルモータとして機能するモータジェネレータ５等、電装品に対するバッテリ１３の放電電流Ｉや、ジェネレータとして機能するモータジェネレータ５からのバッテリ１３に対する充電電流を検出する電流センサ１５と、バッテリ１３に並列接続した無限大抵抗を有し、バッテリ１３の端子電圧Ｖを検出する電圧センサ１７と、エンジン３が配置されたエンジンルーム（図示せず）の温度ｈを検出する温度センサ１９（温度検出手段に相当）とを備えている。
【００８２】
また、本実施形態のバッテリ容量演算装置１は、上述した電流センサ１５、電圧センサ１７、及び、温度センサ１９の出力がインタフェース回路（以下、「Ｉ／Ｆ」と略記する。）２１におけるＡ／Ｄ変換後に取り込まれるマイクロコンピュータ（以下、「マイコン」と略記する。）２３と、このマイコン２３に接続された不揮発性メモリ（以下、「ＮＶＭ」と略記する。）２５，２７とをさらに備えている。
【００８３】
そして、前記マイコン２３は、ＣＰＵ２３ａ、ＲＡＭ２３ｂ、及び、ＲＯＭ２３ｃを有しており、このうち、ＣＰＵ２３ａには、ＲＡＭ２３ｂ及びＲＯＭ２３ｃの他、前記Ｉ／Ｆ２１及びＮＶＭ２５，２７が各々接続されており、また、上述した不図示のスタータスイッチ、イグニッションスイッチやアクセサリスイッチ、モータジェネレータ５以外の電装品（負荷）のスイッチ等が、さらに接続されている。
【００８４】
前記ＲＡＭ２３ｂは、各種データ記憶用のデータエリア及び各種処理作業に用いるワークエリアを有しており、前記ＲＯＭ２３ｃには、ＣＰＵ２３ａに各種処理動作を行わせるための制御プログラムと、前記ＮＶＭ２５にバッテリ１３の開回路電圧ＯＣＶが格納、記憶された時点のバッテリ１３自体又は周辺の温度ｈ₁ と、後述する処理によって推定される、定負荷放電状態における推定上の端子電圧Ｖである推定電圧Ｖｎの推定時点におけるバッテリ１３自体又は周辺の温度ｈ₂ とに応じて、前記ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀ を補正するための補正データとが格納されている。
【００８５】
尚、ＲＯＭ２３ｃに格納されている残存電圧降下値ｅ₀ の補正データは、図３に示すグラフのように、温度０゜Ｃの時の補正係数を「１」とした場合の、温度０゜Ｃ〜温度５５゜Ｃの各温度における補正係数を表した、いわば、温度対補正係数のテーブルのようなものである。
【００８６】
前記ＮＶＭ２５（開回路電圧値記憶手段に相当）には、充電容量の変化に応じて変化する前記バッテリ１３の平衡状態、即ち、充放電時の分極による電圧上昇や電圧降下が完全に解消して残っていない状態における端子電圧Ｖが、バッテリ１３の開回路電圧ＯＣＶとして格納、記憶されると共に、その開回路電圧ＯＣＶが格納、記憶された時点で温度センサ１９が検出したエンジンルームの温度が、バッテリ１３自体又は周辺の温度ｈ₁ として格納、記憶される。
【００８７】
尚、ハイブリッド車両が製造された当初の時点では、実装時に別途計測されたバッテリ１３の端子電圧Ｖが、開回路電圧ＯＣＶとしてＮＶＭ２５に予め格納、記憶されていると共に、その開回路電圧ＯＣＶが格納、記憶された時点のバッテリ１３自体又は周辺の温度が、バッテリ１３自体又は周辺の温度ｈ₁ としてＮＶＭ２５に予め格納、記憶されている。
【００８８】
前記ＮＶＭ２７（残存電圧降下値記憶手段に相当）には、不図示のイグニッションスイッチのオンに伴って、モータジェネレータ５によりエンジン３を始動させるためにバッテリ１３が瞬時的に定負荷放電を行った際に、その定負荷放電中に電流センサ１５や電圧センサ１７により検出されたバッテリ１３の端子電圧Ｖと放電電流Ｉとの相関を基にして、後述する処理によって推定される、定負荷放電状態における推定上の端子電圧Ｖである推定電圧Ｖｎを、ＮＶＭ２５に格納、記憶されているバッテリ１３の開回路電圧ＯＣＶから差し引いた、バッテリ１３の放電終了時における残存分極の影響による残存電圧降下量である残存電圧降下値ｅ₀ が、格納、記憶される。
【００８９】
尚、上述した電流センサ１５、電圧センサ１７、及び、温度センサ１９の出力は、Ｉ／Ｆ２１を介して常時マイコン２３のＣＰＵ２３ａに取り込まれる。
【００９０】
次に、前記ＲＯＭ２３ｃに格納された制御プログラムに従いＣＰＵ２３ａが行う処理を、図４乃至図７のフローチャートを参照して説明する。
【００９１】
バッテリ１３からの給電を受けてマイコン２３が起動しプログラムがスタートすると、ＣＰＵ２３ａは、まず、図４にメインルーチンのフローチャートで示すように、初期設定を実行する（ステップＳ１）。
【００９２】
このステップＳ１における初期設定では、ＲＡＭ２３ｂのワークエリアに設けられたフラグエリアのフラグのリセットやタイマエリアのゼロリセット及びタイムカウントの開始等を行う。
【００９３】
ステップＳ１の初期設定が済んだならば、次に、開回路電圧更新処理（ステップＳ３）と充電状態演算処理（ステップＳ５）とを続けて行った後、バッテリ１３からの給電が断たれたか否かを確認し（ステップＳ７）、断たれていない場合は（ステップＳ７でＮ）、ステップＳ３にリターンし、断たれた場合は（ステップＳ７でＹ）、終了処理を行った後（ステップＳ９）、一連の処理を終了する。
【００９４】
そして、ステップＳ３の開回路電圧更新処理においては、図５にサブルーチンのフローチャートで示すように、ＲＡＭ２３ｂのタイマエリアにおけるタイマ値Ｔが、最大分極発生状態からの分極解消に必要な所定時間Ｔｈを超えているか否かを確認し（ステップＳ３ａ）、所定時間Ｔｈを超えていない場合は（ステップＳ３ａでＮ）、開回路電圧更新処理を終了して図４のメインルーチンにリターンし、超えた場合は（ステップＳ３ａでＹ）、電圧センサ１７の検出したバッテリ１３の端子電圧ＶのＡ／Ｄ変換値をＩ／Ｆ２１から取得すると共に（ステップＳ３ｂ）、温度センサ１９の検出した不図示のエンジンルームの温度ｈのＡ／Ｄ変換値をＩ／Ｆ２１から取得する（ステップＳ３ｃ）。
【００９５】
続いて、ＮＶＭ２５に格納、記憶されているバッテリ１３の開回路電圧ＯＣＶと、その開回路電圧ＯＣＶが格納、記憶された時点のバッテリ１３自体又は周辺の温度ｈ₁ を、ステップＳ３ｂ及びステップＳ３ｃで取得したバッテリ１３の端子電圧Ｖやエンジンルームの温度ｈのＡ／Ｄ変換値に更新し（ステップＳ３ｄ）、ＲＡＭ２３ｂの平衡状態フラグエリアのフラグＦを「１」に設定した後（ステップＳ３ｅ）、開回路電圧更新処理を終了して図４のメインルーチンにリターンする。
【００９６】
また、ステップＳ５の充電状態演算処理では、図６にサブルーチンのフローチャートで示すように、スタータスイッチ以外のスイッチの状態がオフからオンに移行したか否かを確認し（ステップＳ５ａ）、移行していない場合は（ステップＳ５ａでＮ）、後述するステップＳ５ｆに進み、移行した場合は（ステップＳ５ａでＹ）、Ｉ／Ｆ２１からＡ／Ｄ変換値として取得される電流センサ１５の検出したバッテリ１３の放電電流Ｉが０Ａ（アンペア）であるか否かを確認する（ステップＳ５ｂ）。
【００９７】
バッテリ１３の放電電流Ｉが０Ａ（アンペア）でない場合は（ステップＳ５ｂでＮ）、ＲＡＭ２３ｂのタイマエリアにおけるタイムカウントを終了させると共にタイマ値Ｔをゼロリセットし（ステップＳ５ｃ）、平衡状態フラグエリアのフラグＦを「０」に設定した後（ステップＳ５ｄ）、充電状態演算処理を終了して図４のメインルーチンにリターンし、バッテリ１３の放電電流Ｉが０Ａ（アンペア）である場合は（ステップＳ５ｂでＹ）、スタータスイッチがオンされたか否かを確認する（ステップＳ５ｅ）。
【００９８】
スタータスイッチがオンされていない場合は（ステップＳ５ｅでＮ）、充電状態演算処理を終了して図４のメインルーチンにリターンし、オンされた場合は（ステップＳ５ｅでＹ）、後述するステップＳ５ｊに進む。
【００９９】
一方、ステップＳ５ａにおいてスタータスイッチ以外のスイッチの状態がオフからオンに移行していない場合（Ｎ）に進むステップＳ５ｆでは、スタータスイッチ以外のスイッチの状態がオンからオフに移行したか否かを確認し、移行していない場合は（ステップＳ５ｆでＮ）、後述するステップＳ５ｈに進み、移行した場合は（ステップＳ５ｆでＹ）、ＲＡＭ２３ｂのタイマエリアにおけるタイムカウントを開始させた後（ステップＳ５ｇ）、充電状態演算処理を終了して図４のメインルーチンにリターンする。
【０１００】
また、ステップＳ５ｆにおいてスタータスイッチ以外のスイッチの状態がオンからオフに移行していない場合（Ｎ）に進むステップＳ５ｈでは、スタータスイッチがオンされたか否かを確認し（ステップＳ５ｈ）、オンされていない場合は（ステップＳ５ｈでＮ）、充電状態演算処理を終了して図４のメインルーチンにリターンし、オンされた場合は（ステップＳ５ｈでＹ）、ステップＳ５ｊに進む。
【０１０１】
ステップＳ５ｅ及びステップＳ５ｈにおいてスタータスイッチがオンされた場合（Ｙ）に各々進むステップＳ５ｊでは、図７のフローチャートに示すように、Ｉ／Ｆ２１からＡ／Ｄ変換値として取得される電流センサ１５の検出したバッテリ１３の放電電流Ｉが２５０Ａ（アンペア）に達した後に２５０Ａ（アンペア）から減少し始めたか否かを確認する。
【０１０２】
バッテリ１３の放電電流Ｉが２５０Ａ（アンペア）に達した後に２５０Ａ（アンペア）から減少し始めていない場合は（ステップＳ５ｊでＮ）、そのようになるまでステップＳ５ｊをリピートし、２５０Ａ（アンペア）に達した後に２５０Ａ（アンペア）から減少し始めた場合は（ステップＳ５ｊでＹ）、電流センサ１５の検出したバッテリ１３の放電電流ＩのＡ／Ｄ変換値と、電圧センサ１７の検出したバッテリ１３の端子電圧ＶのＡ／Ｄ変換値とを、対にしてＩ／Ｆ２１から取得し（ステップＳ５ｋ）、その取得した、電流センサ１５の検出したバッテリ１３の放電電流Ｉが３５Ａ（アンペア）まで低下した否かを確認する（ステップＳ５ｍ）。
【０１０３】
バッテリ１３の放電電流Ｉが３５Ａ（アンペア）まで低下していない場合は（ステップＳ５ｍでＮ）、ステップＳ５ｋにリターンし、低下した場合は（ステップＳ５ｍでＹ）、それまでの間にステップＳ５ｋにおいて対にして取得された、複数組のバッテリ１３の端子電圧Ｖと放電電流ＩとのＡ／Ｄ変換値を利用し、そのデータの相関性を確認するための相関係数ｒを算出してその値が−０．９≧ｒ≧−１．０の許容範囲内にあるか否かを確認する（ステップＳ５ｎ）。
【０１０４】
相関係数ｒが許容範囲内にあって相関がＯＫである場合は（ステップＳ５ｎでＹ）、後述するステップＳ５ｔに進み、相関係数ｒが許容範囲内になく相関がＯＫでない場合は（ステップＳ５ｎでＮ）、ステップＳ５ｋで取得した、電流センサ１５の検出したバッテリ１３の放電電流Ｉと電圧センサ１７の検出したバッテリ１３の端子電圧ＶとのＡ／Ｄ変換値の対を破棄した後（ステップＳ５ｐ）、平衡状態フラグエリアのフラグＦが「０」であるか否かを確認する（ステップＳ５ｒ）。
【０１０５】
フラグＦが「０」である場合は（ステップＳ５ｒでＹ）、充電状態演算処理を終了して図４のメインルーチンにリターンし、「０」でない場合は（ステップＳ５ｒでＮ）、フラグＦを「０」に設定した後（ステップＳ５ｓ）、充電状態演算処理を終了して図４のメインルーチンにリターンする。
【０１０６】
また、ステップＳ５ｎにおいて相関係数ｒが許容範囲内にあって相関がＯＫである場合（Ｙ）に進むステップＳ５ｔでは、ステップＳ５ｋで取得した、電流センサ１５の検出したバッテリ１３の放電電流Ｉと電圧センサ１７の検出したバッテリ１３の端子電圧ＶとのＡ／Ｄ変換値の対に、最小二乗法を適用して、直線的な電圧−電流特性式Ｖ＝ａＩ＋ｂを割り出し、次に、定電流放電における推定電圧Ｖｎがバッテリ１３の容量に対して直線的な特性を示すようになる仮想電流値Ｉｓ＝−１０Ａ（アンペア）を、ステップＳ５ｔで割り出した電圧−電流特性式Ｖ＝ａＩ＋ｂに代入して、推定電圧Ｖｎを推定する（ステップＳ５ｖ）。
【０１０７】
これと共に、温度センサ１９の検出した不図示のエンジンルームの温度ｈのＡ／Ｄ変換値を、推定電圧Ｖｎの推定時点におけるバッテリ１３自体又は周辺の温度ｈ₂ としてＩ／Ｆ２１から取得した後（ステップＳ５ｗ）、平衡状態フラグエリアのフラグＦが「０」であるか否かを確認する（ステップＳ５ｘ）。
【０１０８】
フラグＦが「０」である場合は（ステップＳ５ｘでＹ）、後述するステップＳ５Ｂに進み、「０」でない場合は（ステップＳ５ｘでＮ）、ＮＶＭ２５に格納、記憶されている開回路電圧ＯＣＶからステップＳ５ｖで推定した推定電圧Ｖｎを差し引いて残存電圧降下値ｅ₀ を求め（ステップＳ５ｙ）、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀ をステップＳ５ｙで求めた残存電圧降下値ｅ₀ に更新し（ステップＳ５ｚ）、更新されたＮＶＭ２７の残存電圧降下値ｅ₀ に、ステップＳ５ｖで推定した推定電圧Ｖｎを加算して、補正後推定電圧Ｖｎ´を求めた後（ステップＳ５Ａ）、後述するステップＳ５Ｄに進む。
【０１０９】
また、ステップＳ５ｘにおいて平衡状態フラグエリアのフラグＦが「０」である場合（Ｙ）に進むステップＳ５Ｂでは、ステップＳ５ｖで取得した推定電圧Ｖｎの推定時点におけるバッテリ１３自体又は周辺の温度ｈ₂ と、ＮＶＭ２５に格納、記憶されている、バッテリ１３の開回路電圧ＯＣＶがＮＶＭ２５に格納、記憶された時点のバッテリ１３自体又は周辺の温度ｈ₁ とに基づいて、ＲＯＭ２３ｃに格納されている補正データの係数によって、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀ を補正して補正後残存電圧降下値ｅ₀ ´を求め、続いて、この補正後残存電圧降下値ｅ₀ ´をステップＳ５ｖで取得した推定電圧Ｖｎに加算して補正後推定電圧Ｖｎ´を求めた後（ステップＳ５Ｃ）、ステップＳ５Ｄに進む。
【０１１０】
ステップＳ５ＡやステップＳ５Ｃにおいて補正後推定電圧Ｖｎ´を求めた後に各々進むステップＳ５Ｄでは、ステップＳ５ＡやステップＳ５Ｃにおいて求めた補正後推定電圧Ｖｎ´を、電圧比による算出式、
ＳＯＣ＝｛（Ｖｎ´−Ｖｅ）／（Ｖｓ−Ｖｅ）｝×１００（％）
又は、電力比による算出式、

（但し、Ｖｓは満充電時の開回路電圧、Ｖｅは放電終止時の開回路電圧）
のいずれかの式に代入して、バッテリ１３の充電状態ＳＯＣを求める。
【０１１１】
続いて、平衡状態フラグエリアのフラグＦが「０」であるか否かを確認し（ステップＳ５Ｅ）、「０」である場合は（ステップＳ５ＥでＹ）、充電状態演算処理を終了して図４のメインルーチンにリターンし、「０」でない場合は（ステップＳ５ＥでＮ）、平衡状態フラグＦを「０」に設定した後（ステップＳ５Ｆ）、充電状態演算処理を終了して図４のメインルーチンにリターンする。
【０１１２】
以上の説明からも明らかなように、本実施形態のバッテリ容量演算装置１では、図７のフローチャートにおけるステップＳ５ｔが、請求項中の特性割出手段２３Ａに対応する処理となっており、図７中のステップＳ５ｖが、請求項中の推定電圧推定手段２３Ｂに対応する処理となっていると共に、図７中のステップＳ５ｊが、請求項中の残存電圧降下値割出手段２３Ｄに対応する処理となっている。
【０１１３】
また、本実施形態のバッテリ容量演算装置１では、図５のフローチャートにおけるステップＳ３ａが、請求項中の平衡状態判別手段２３Ｃに対応する処理となっており、図５中のステップＳ３ｄが、請求項中の開回路電圧更新手段２３Ｅに対応する処理となっていると共に、図７中のステップＳ５Ｂが、請求項中の補正手段２３Ｆに対応する処理となっている。
【０１１４】
さらに、本実施形態のバッテリ容量演算装置１では、電流センサ１５と、図７中のステップＳ５ｊとにより、請求項中の放電電流減少開始検出手段Ａが構成されており、電流センサ１５と、図７中のステップＳ５ｍとにより、請求項中の放電電流低下検出手段Ｃが構成されていると共に、電圧センサ１７と、図５中のステップＳ３ｂとにより、請求項中の平衡状態端子電圧測定手段Ｂが構成されている。
【０１１５】
また、本実施形態のバッテリ容量演算装置１では、バッテリ１３の放電電流Ｉに関して、２５０Ａ（アンペア）が請求項中の所定の大電流値に相当しており、３５Ａ（アンペア）が請求項中の目標電流値に相当している。
【０１１６】
次に、上述のように構成された本実施形態のバッテリ容量演算装置１の動作（作用）について説明する。
【０１１７】
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て、それに伴いバッテリ１３が放電を行っている状態、或は、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て、それに伴いバッテリ１３が充電を行っている状態では、ＮＶＭ２５に格納、記憶されている開回路電圧ＯＣＶと、その開回路電圧ＯＣＶがＮＶＭ２５に格納、記憶された時点のバッテリ１３自体又は周辺の温度ｈ₁ の更新や、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀ の更新は、いずれも行われず、また、推定電圧Ｖｎの推定とこれを用いた充電状態ＳＯＣの演算、更新も行われない。
【０１１８】
次に、スタータスイッチのオンに伴って、ハイブリッド車両のモータジェネレータ５がセルモータとして機能するように作動し、これに伴いバッテリ１３が２５０Ａ（アンペア）を超える所定の大電流値による定負荷放電を行うと、その放電におけるバッテリ１３の放電電流Ｉが３５Ａ（アンペア）という目標電流値に低下するまでの間、電流センサ１５及び電圧センサ１７により検出されたバッテリ１３の放電電流Ｉ及び端子電圧Ｖが、対となって周期的に収集され、一定の相関関係を満たすものであった場合には、これらに最小二乗法を適用して、バッテリ１３の直線的な電圧−電流特性式Ｖ＝ａＩ＋ｂが割り出され、定電流放電における推定電圧Ｖｎがバッテリ１３の容量に対して直線的な特性を示すようになる仮想電流値Ｉｓ＝−１０Ａ（アンペア）を、この電圧−電流特性式Ｖ＝ａＩ＋ｂに代入することで、推定電圧Ｖｎが推定される。
【０１１９】
そして、推定電圧Ｖｎの推定時点におけるバッテリ１３自体又は周辺の温度ｈ₂ と、ＮＶＭ２５に格納、記憶されている、バッテリ１３の開回路電圧ＯＣＶがＮＶＭ２５に格納、記憶された時点のバッテリ１３自体又は周辺の温度ｈ₁ とに差があれば、その差に応じて、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀ が温度補償のために補正され、この補正された補正後残存電圧降下値ｅ₀ ´を、先に推定された推定電圧Ｖｎに加算することで、補正後推定電圧Ｖｎ´が求められ、この補正後推定電圧Ｖｎ´を、電圧比又は電力比のいずれかの算出式に代入することで、バッテリ１３の充電状態ＳＯＣが演算されて、その結果が、表示や容量管理のデータとして提供される。
【０１２０】
この場合、推定電圧Ｖｎを推定するのに用いるバッテリ１３の電圧−電流特性式Ｖ＝ａＩ＋ｂを求めるために、対となって周期的に収集される、バッテリ１３の放電電流Ｉ及び端子電圧Ｖが、２５０Ａ（アンペア）という、ハイブリッド車両における最大の負荷であるセルモータとして機能させるモータジェネレータ５に対する放電の際に収集されたものであり、しかも、他の負荷に複数同時にバッテリ１３の電力が供給されていても到達しない３５Ａ（アンペア）を超える放電電流Ｉが流れている状態で収集されたものである。
【０１２１】
このため、モータジェネレータ５以外の負荷にバッテリ１３の電力が同時に供給されていて、それによる放電側分極による電圧降下が生じていても、モータジェネレータ５に対する放電の終了時における残存分極の影響による残存電圧降下量として求められた残存電圧降下値ｅ₀ を、推定した推定電圧Ｖｎに加算することで、バッテリ１３の実際の充電状態ＳＯＣを正確に演算することができる。
【０１２２】
また、本実施形態のバッテリ容量演算装置１では、スタータスイッチのオンに伴って、バッテリ１３が２５０Ａ（アンペア）を超える定負荷放電を行った場合、その放電開始前の段階で、最大分極発生状態からの分極解消に必要な所定時間Ｔｈを超えて、バッテリ１３が充放電を行っていないと、前回にバッテリ１３が充放電を行った際に発生した分極による電圧変動（電圧上昇又は電圧降下）が完全に解消して平衡状態となっているものとして、ＮＶＭ２５に格納、記憶されているバッテリ１３の開回路電圧ＯＣＶが、この時点で検出されたバッテリ１３の端子電圧Ｖに更新される。
【０１２３】
このため、バッテリ１３の容量変化によって開回路電圧ＯＣＶが変動しても、バッテリ１３が平衡状態となる毎に、ＮＶＭ２５に格納、記憶される開回路電圧ＯＣＶを最新の値に更新して、バッテリ１３の充電状態ＳＯＣの演算精度を高く維持することができる。
【０１２４】
同様に、本実施形態のバッテリ容量演算装置１では、セルモータとして機能させるモータジェネレータ５に対するバッテリ１３の放電が、バッテリ１３が平衡状態にある状況から行われると、ＮＶＭ２７に格納、記憶されているバッテリ１３の残存電圧降下値ｅ₀ が、放電開始前に更新されたＮＶＭ２５の開回路電圧ＯＣＶから、放電後に推定された推定電圧Ｖｎを差し引いた、最新の残存電圧降下値ｅ₀ に更新される。
【０１２５】
このため、バッテリ１３の状態変化に伴って残存電圧降下値ｅ₀ が変動しても、バッテリ１３が平衡状態となる毎に、ＮＶＭ２７に格納、記憶される残存電圧降下値ｅ₀ を最新の値に更新して、バッテリ１３の充電状態ＳＯＣの演算精度を高く維持することができる。
【０１２６】
さらに、本実施形態のバッテリ容量演算装置１では、ＮＶＭ２５に開回路電圧ＯＣＶを格納、記憶した時点におけるバッテリ１３自体又は周辺の温度ｈ₁ と、推定電圧Ｖｎの推定時点におけるバッテリ１３自体又は周辺の温度ｈ₂ とが異なる場合に、その相違に応じた温度補償のための補正が残存電圧降下値ｅ₀ に対して行われ、推定電圧Ｖｎに加算してバッテリ１３の充電状態ＳＯＣを演算するのに用いられるのが、補正後残存電圧降下値ｅ₀ ´となることから、残存電圧降下値ｅ₀ を求めた時点と、この残存電圧降下値ｅ₀ を推定電圧Ｖｎに加算してバッテリ１３の充電状態ＳＯＣを演算する時点とで、開回路電圧ＯＣＶの値に変化を及ぼすバッテリ１３自体又は周辺の温度ｈの変化が生じていても、それを考慮に入れてバッテリ１３の充電状態ＳＯＣを精度良く演算することができる。
【０１２７】
ちなみに、本実施形態で採用した上述の、残存電圧降下値ｅ₀ の温度補償のための構成や、開回路電圧ＯＣＶ及び（又は）残存電圧降下値ｅ₀ の更新のための構成の一部又は全部は、必要とされる精度との関係において支障がない限り、省略しても良い。
【０１２８】
また、推定電圧Ｖｎを推定するのに用いるバッテリ１３の電圧−電流特性式Ｖ＝ａＩ＋ｂを求めるために、バッテリ１３の放電電流Ｉ及び端子電圧Ｖを対にして周期的に収集する期間は、本実施形態のバッテリ容量演算装置１のように、バッテリ１３が２５０Ａ（アンペア）を超える定負荷放電を行った場合、その放電電流Ｉが２５０Ａ（アンペア）から３５Ａ（アンペア）に減少する間に限らなくても良い。
【０１２９】
しかし、一般にバッテリ１３の放電時における電圧−電流特性は、図８のグラフに示すように、放電電流Ｉの増加時と減少時とで異なり、実際にバッテリ１３が２５０Ａ（アンペア）を超える定負荷放電を行った場合の放電電流Ｉと端子電圧Ｖとを測定してみると、図９のグラフに示すように、放電によりバッテリ１３に発生した分極による電圧降下が放電電流Ｉの減少に伴って解消するペースが、放電電流Ｉの増加に伴う発生のペースに対して遅れることから、放電電流Ｉの増加時よりも減少時の方が放電電流Ｉに対して端子電圧Ｖが低くなる。
【０１３０】
しかも、前回の充放電による電圧上昇や電圧降下が残った状態でバッテリ１３の放電が開始されると、図１０のグラフに一般的な傾向を示すように、放電電流Ｉの増加中における電圧−電流特性が、先に図８のグラフを参照して説明した、平衡状態から放電を開始した場合の放電電流Ｉの増加中における電圧−電流特性とは異なってしまう。
【０１３１】
したがって、放電電流Ｉの増加中と減少中とでバッテリ１３の電圧−電流特性が同じ特性とならず、しかも、放電電流Ｉの増加中における電圧−電流特性については、放電の開始前のバッテリ１３が平衡状態にあったか否かによっても異なることを考慮すると、その特性差がよほど僅かな誤差程度の影響しか及ぼさないという状況が確保されていない限り、少なくとも、本実施形態のバッテリ容量演算装置１のように、放電電流Ｉが減少している間に限って周期的に収集したバッテリ１３の放電電流Ｉ及び端子電圧Ｖのみを用いて、バッテリ１３の電圧−電流特性式Ｖ＝ａＩ＋ｂを求める方が、好ましいと言える。
【０１３２】
そして、本実施形態のバッテリ容量演算装置１では、ＮＶＭ２５に格納、記憶されているバッテリ１３の開回路電圧ＯＣＶが、図８中の放電電流Ｉの増加中における電圧−電流特性線の、放電電流Ｉ＝０Ａ（アンペア）上の点を示すことになり、放電電流Ｉが２５０Ａ（アンペア）から３５Ａ（アンペア）に減少する間に収集したバッテリ１３の放電電流Ｉ及び端子電圧Ｖのみを用いて求めた、バッテリ１３の電圧−電流特性を表わす式から推定される推定電圧Ｖｎが、図８中の放電電流Ｉの減少中における電圧−電流特性線の、仮想電流値Ｉｓ＝−１０Ａ（アンペア）上の点を示すことになる。
【０１３３】
また、本実施形態では、定負荷放電時におけるバッテリ１３の電圧−電流特性を、１次の電圧−電流特性式Ｖ＝ａＩ＋ｂに近似させているが、分極抵抗成分の非直線形の特性の影響も考慮して、１次の電圧−電流特性式Ｖ＝ａＩ＋ｂに代えて、図１１に示すように、定負荷放電時におけるバッテリ１３の放電電流Ｉ及び端子電圧Ｖの対から最小二乗法によって得られる、Ｖ＝ａＩ² ＋ｂＩ＋ｃなる２次の曲線式に近似させるようにしてもよい。
【０１３４】
そして、そのようにした場合は、この近似曲線式Ｖ＝ａＩ² ＋ｂＩ＋ｃに仮想電流値Ｉｓ＝−１０Ａ（アンペア）を代入することで、推定電圧Ｖｎを推定し、推定した推定電圧Ｖｎを用いて最新の残存電圧降下値ｅ₀ を求めて更新設定したり、推定した推定電圧Ｖｎに残存電圧降下値ｅ₀ を加算してバッテリ１３の開回路電圧ＯＣＶを演算することになる。
【０１３５】
このように、バッテリ１３の電圧−電流特性を２次の近似曲線式とすれば、放電による分極に起因してバッテリ１３に生じる端子電圧Ｖの電圧降下量の増減のペースに対する、放電電流Ｉの増減のペースの鈍さが、１次の電圧−電流特性式Ｖ＝ａＩ＋ｂよりも一層正確に反映されて、この近似曲線式Ｖ＝ａＩ² ＋ｂＩ＋ｃを用いて推定される推定電圧Ｖｎの精度や、この推定電圧Ｖｎを用いて演算される開回路電圧ＯＣＶの精度を、より高めることができるので、有利である。
【０１３６】
さらに、本実施形態では、単独で最も多くの電力を消費するモータジェネレータ５の作動時における、２５０Ａ（アンペア）を超える定負荷放電時のバッテリ１３の放電電流Ｉ及び端子電圧Ｖを用いて、分極の影響を含んだ電圧−電流特性式Ｖ＝ａＩ＋ｂの割り出しを行ったが、少なくとも放電直前にバッテリ１３に発生していた充電側分極を解消するのに十分な電流値であれば、放電電流の最大値が２５０Ａ（アンペア）に遠く及ばないような、モータジェネレータ５以外の負荷の動作に伴うバッテリ１３の放電電流Ｉ及び端子電圧Ｖを用いて、分極の影響を含んだ電圧−電流特性式Ｖ＝ａＩ＋ｂや、上述したＶ−Ｉ特性の２つの近似曲線式Ｍ１及びＭ２の割り出しを行ってもよい。
【０１３７】
【発明の効果】
以上に説明したように請求項１に記載した本発明のバッテリ容量演算方法によれば、車両の負荷に電力を供給するバッテリの端子電圧と放電電流とを周期的に測定してこれら端子電圧と放電電流との相関を示す電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式を用いて前記バッテリの定負荷放電状態における推定上の端子電圧である推定電圧を推定し、この推定電圧を用いて前記バッテリの充電容量を演算するに当たり、
各種の充電容量におけるバッテリの電圧―電流特性を表わす式に基づいて、前記充電容量の変化に対応して直線的に変化する電圧を与える電流の値を仮想電流値として、あらかじめ、求めておき、平衡状態の前記バッテリによる定負荷放電の放電電流が、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値から減少している間の、前記電圧−電流特性を表わす式に仮想電流値を代入して推定した、前記所定の大電流値による定負荷放電時における前記バッテリの推定電圧の値と、該推定電圧の値を推定するのに用いた前記定負荷放電の開始前における平衡状態の前記バッテリの端子電圧である開回路電圧の値との差値を、前記バッテリの放電終了時における残存分極の影響による残存電圧降下量である残存電圧降下値として予め求めておき、以後、前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行う毎に、該定負荷放電中に周期的に測定した前記バッテリの端子電圧と放電電流とから前記電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に前記仮想電流値を代入して前記バッテリの現在の推定電圧を推定し、前記推定した前記バッテリの現在の推定電圧の値に、前記残存電圧降下値を加算することで、前記バッテリの現在の充電容量を演算するようにした。
【０１３８】
このため、放電電流と共に定負荷放電中に周期的に測定したバッテリの端子電圧が、放電による電圧降下を含んでいて、この端子電圧を用いて求めたバッテリの電圧−電流特性を表わす式や、この電圧−電流特性を表わす式から推定したバッテリの現在の推定電圧が、放電による電圧降下を反映したものとなったとしても、推定電圧に反映されている電圧降下成分と同等の、車両の負荷への最大供給電力値に相当する所定の大電流値によってバッテリが行った定負荷放電の終了時における残存分極の影響による残存電圧降下量である残存電圧降下値を、バッテリの現在の推定電圧の値に加算することで、推定電圧に反映されている電圧降下成分を残存電圧降下値により相殺し、バッテリの充電状態を正確に演算することができる。
【０１３９】
また、請求項２に記載した本発明のバッテリ容量演算方法によれば、請求項１に記載した本発明のバッテリ容量演算方法において、平衡状態の前記バッテリの端子電圧の値を予め測定して該測定値を前記開回路電圧の値に設定しておき、該開回路電圧の設定に続いて、平衡状態の前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行った際、該定負荷放電の放電電流が最大電流値から減少する間に周期的に測定した、前記バッテリの端子電圧と放電電流とから、電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に前記仮想電流値を代入して、平衡状態からの、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧を推定し、該推定した、平衡状態からの、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における、前記バッテリの推定電圧の値を、前記設定した前記開回路電圧の値から差し引くことで、前記残存電圧降下値を予め求めておくようにした。
【０１４０】
このため、請求項１に記載した本発明のバッテリ容量演算方法において、平衡状態のバッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行った際に、開回路電圧の値が取得されて設定されると共に、この取得された開回路電圧から、後に推定される推定電圧を差し引くことで残存電圧降下値が取得されるので、予め開回路電圧や残存電圧降下値を認識しておいてこれを自ら設定しておく必要をなくすことができる。
【０１４１】
さらに、請求項３に記載した本発明のバッテリ容量演算方法によれば、請求項２に記載した本発明のバッテリ容量演算方法において、前記バッテリが平衡状態となる毎に、前記開回路電圧の値を、当該平衡状態において測定した前記バッテリの端子電圧の値に更新設定するようにした。
【０１４２】
このため、請求項２に記載した本発明のバッテリ容量演算方法において、バッテリが平衡状態となる毎に開回路電圧の値を最新のものに更新設定させて、残存電圧降下値についても、開回路電圧の値が最新のものに更新設定される毎に、最新のものを予め求めておくことができるようにして、バッテリの現在の推定電圧に残存電圧降下値を加算して演算されるバッテリの充電状態を、バッテリの充電状態等の変化による開回路電圧の変動に対応して常に正確に演算することができる。
【０１４３】
また、請求項４に記載した本発明のバッテリ容量演算方法によれば、請求項１、２又は３に記載した本発明のバッテリ容量演算方法において、前記バッテリが、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行う毎に、該定負荷放電時の放電電流が最大電流値から減少する間に周期的に測定した、前記バッテリの端子電圧と放電電流とから、前記電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式に仮想電流値を代入して、前記バッテリの現在の推定電圧の推定を行うようにした。
【０１４４】
このため、請求項１、２又は３に記載した本発明のバッテリ容量演算方法において、定負荷放電における放電電流の増加や減少に対して、放電側分極による電圧降下の増加や減少が遅れて生じるために、放電電流の増加中と減少中とでバッテリの電圧−電流特性が相違し、しかも、前回の充放電によって発生した分極によるバッテリの端子電圧の電圧上昇や電圧降下が残存した状態で、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値によるバッテリの定負荷放電が行われる場合であっても、それらの影響を受けず常に同じ特性として現れる電圧−電流特性部分を用いてバッテリの現在の推定電圧が推定されるようにして、バッテリの充電状態の演算を、前回の充放電によって発生した分極による電圧変動の影響を受けずに精度良く行うことができる。
【０１４５】
さらに、請求項５に記載した本発明のバッテリ容量演算方法によれば、請求項１、２、３又は４に記載した本発明のバッテリ容量演算方法において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値を、前記車両のセルモータ始動時に必要とする所定の大電流値とし、前記バッテリの放電電流値が、前記所定の大電流値から減少し始めてから、該所定の大電流値よりも低く、かつ、前記セルモータ以外の前記車両の負荷が駆動されている際における最大放電電流値以上の、目標電流値に低下するまでの間に、周期的に測定した前記バッテリの端子電圧と放電電流とから、前記所定の大電流値による定負荷放電時における前記バッテリの推定電圧を推定するのに用いる前記電圧−電流特性を表わす式を求めるようにした。
【０１４６】
このため、請求項１、２、３又は４に記載した本発明のバッテリ容量演算方法において、セルモータ以外の車両の負荷が今なお駆動されているとしても、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下の、放電電流が目標電流値に低下したことにより解消した分を除く残存成分のみを、純粋に反映したバッテリの端子電圧と放電電流とから、セルモータ以外の車両の負荷に対する電力供給による影響を排除した電圧−電流特性と推定電圧とを取得して、バッテリの充電状態を精度良く演算することができる。
【０１４７】
また、請求項６に記載した本発明のバッテリ容量演算方法によれば、請求項１、２、３、４又は５に記載した本発明のバッテリ容量演算方法において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧を推定する毎に、該推定時点における前記バッテリの周辺温度と、前記開回路電圧を求めた時点における前記バッテリの周辺温度との差の有無を確認し、差がある場合は、その温度差に応じて、前記残存電圧降下値を補正し、該補正した残存電圧降下値を用いて前記バッテリの現在の充電容量を演算するようにした。
【０１４８】
このため、請求項１、２、３、４又は５に記載した本発明のバッテリ容量演算方法において、バッテリの周辺温度が変化してバッテリの容量が変化し、その容量に応じてバッテリの開回路電圧が、残存電圧降下値を予め求める際に用いた開回路電圧に対して変化しても、残存電圧降下値を補正することで温度補償して、現在のバッテリ周辺温度に応じたバッテリの現在の充電容量を精度良く演算することができる。
【０１４９】
さらに、請求項７に記載した本発明のバッテリ容量演算装置によれば、車両の負荷に電力を供給するバッテリの、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時に、この定負荷放電時におけるバッテリの端子電圧と放電電流とを周期的に測定してこれら端子電圧と放電電流との相関を示す電圧−電流特性を表わす式を求め、この電圧−電流特性を表わす式を用いて前記バッテリの定負荷放電状態における推定上の端子電圧である推定電圧を推定し、この推定電圧を用いて前記バッテリの充電容量を演算するバッテリ容量演算装置において、平衡状態の前記バッテリによる定負荷放電の放電電流が、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値から減少している間の、前記電圧−電流特性を表わす式において各種の充電容量におけるバッテリ１３の電圧―電流特性を表わす式に基づいてあらかじめ求めらておいた、前記充電容量の変化に対応して直線的に変化する電圧である推定電圧を与える電流を仮想電流値として代入して、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧の値と、該推定電圧の値を推定するのに用いた前記定負荷放電の開始前における平衡状態の前記バッテリの端子電圧である開回路電圧の値との差値を、前記バッテリの放電終了時における残存分極の影響による残存電圧降下量である残存電圧降下値として記憶する残存電圧降下値記憶手段を備えており、前記残存電圧降下値記憶手段に記憶された前記残存電圧降下値を、前記推定した前記バッテリの推定電圧の値に加算することで、前記バッテリの現在の充電容量を演算する構成とした。
【０１５０】
このため、放電電流と共に定負荷放電中に周期的に測定したバッテリの端子電圧が、放電による電圧降下を含んでいて、この端子電圧を用いて求めたバッテリの電圧−電流特性を表わす式や、この電圧−電流特性を表わす式から推定したバッテリの現在の推定電圧が、放電による電圧降下を反映したものとなったとしても、推定電圧に反映されている電圧降下成分と同等の、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値によってバッテリが行った定負荷放電の終了時における残存分極の影響による残存電圧降下量である、残存電圧降下値記憶手段に記憶された残存電圧降下値を、バッテリの現在の推定電圧の値に加算することで、推定電圧に反映されている電圧降下成分を残存電圧降下値により相殺し、バッテリの充電状態を正確に演算すること
ができる。
【０１５１】
また、請求項８に記載した本発明のバッテリ容量演算装置によれば、請求項７に記載した本発明のバッテリ容量演算装置において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値による前記バッテリの定負荷放電において、該バッテリの放電電流が最大電流値から減少し始めたことを検出する放電電流減少開始検出手段と、前記バッテリの放電電流が最大電流値から減少し始めたことを前記放電電流減少開始検出手段が検出した後に、周期的に測定される前記バッテリの端子電圧と放電電流とから前記電圧−電流特性を表わす式を求める特性割出手段と、該特性割出手段が求めた前記電圧−電流特性を表わす式に仮想電流値を代入して、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時における前記バッテリの推定電圧を推定する推定電圧推定手段とをさらに備えており、該推定電圧推定手段が推定した前記バッテリの推定電圧の値に、前記残存電圧降下値記憶手段に記憶された前記残存電圧降下値を加算することで、前記バッテリの現在の充電容量を演算する構成とした。
【０１５２】
このため、請求項７に記載した本発明のバッテリ容量演算装置において、定負荷放電における放電電流の増加や減少に対して、放電側分極による電圧降下の増加や減少が遅れて生じるために、放電電流の増加中と減少中とでバッテリの電圧−電流特性が相違し、しかも、前回の充放電によって発生した分極によるバッテリの端子電圧の電圧上昇や電圧降下が残存した状態で、所定の大電流値によるバッテリの定負荷放電が行われる場合であっても、それらの影響を受けず常に同じ特性として現れる電圧−電流特性を表わす式を特性割出手段により求め、この特性割出手段が求めた電圧−電流特性を表わす式に仮想電流値を代入して得た推定電圧推定手段が推定したバッテリの現在の推定電圧を用いて、バッテリの充電状態を演算するようにして、バッテリの充電状態の演算を、前回の充放電によって発生した分極による電圧変動の影響を受けずに精度良く行うことができる。
【０１５３】
さらに、請求項９に記載した本発明のバッテリ容量演算装置によれば、請求項８に記載した本発明のバッテリ容量演算装置において、前記開回路電圧の値を記憶する開回路電圧値記憶手段と、前記バッテリが平衡状態にあるか否かを判別する平衡状態判別手段と、該平衡状態判別手段により平衡状態にあると判別された前記バッテリからの、少なくとも放電直前に該バッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電時に、前記推定電圧推定手段が推定した前記バッテリの推定電圧の値を、前記開回路電圧値記憶手段に記憶された前記開回路電圧の値から差し引いて前記残存電圧降下値を求める残存電圧降下値割出手段とをさらに備えており、前記残存電圧降下値記憶手段が、前記残存電圧降下値割出手段が求めた前記残存電圧降下値を記憶する構成とした。
【０１５４】
このため、請求項８に記載した本発明のバッテリ容量演算装置において、平衡状態判別手段により平衡状態にあると判別されたバッテリが、少なくとも放電直前にバッテリに発生していた充電側分極を解消するのに十分な電流値による定負荷放電を行った際に、推定電圧推定手段が推定した推定電圧の値を用いて、残存電圧降下値記憶手段に記憶させる残存電圧降下値が残存電圧降下値割出手段により求められるようにして、予め残存電圧降下値を認識しておいてこれを自ら設定しておく必要をなくすことができる。
【０１５５】
また、請求項１０に記載した本発明のバッテリ容量演算装置によれば、請求項９に記載した本発明のバッテリ容量演算装置において、前記平衡状態判別手段により平衡状態にあると判別された状態において前記バッテリの端子電圧を測定する平衡状態端子電圧測定手段と、前記開回路電圧値記憶手段に記憶された前記開回路電圧の値を、前記平衡状態端子電圧測定手段が測定した前記バッテリの端子電圧の値に更新する開回路電圧更新手段とをさらに備えている構成とした。
【０１５６】
このため、請求項９に記載した本発明のバッテリ容量演算装置において、平衡状態判別手段によりバッテリが平衡状態にあると判別される毎に、開回路電圧値記憶手段に記憶された開回路電圧の値が、平衡状態端子電圧測定手段により測定されるバッテリの端子電圧の値に、開回路電圧更新手段によって更新されるようにして、開回路電圧値記憶手段に記憶される開回路電圧の値を常に最新のものに更新させて、バッテリの現在の推定電圧に残存電圧降下値を加算して演算されるバッテリの充電状態を、バッテリの充電状態等の変化による開回路電圧の変動に対応して常に正確に演算することができる。
【０１５７】
さらに、請求項１１に記載した本発明のバッテリ容量演算装置によれば、請求項１０に記載した本発明のバッテリ容量演算装置において、前記バッテリの周辺温度を検出する温度検出手段と、前記バッテリの推定電圧を前記推定電圧推定手段が推定した時点において、前記温度検出手段が検出した前記バッテリの周辺温度と、前記バッテリの端子電圧を前記平衡状態端子電圧測定手段が測定した時点において、前記温度検出手段が検出した前記バッテリの周辺温度との差の有無を確認し、差がある場合は、その温度差に応じて、前記残存電圧降下値記憶手段に記憶された前記残存電圧降下値を補正する補正手段とをさらに備えており、該補正手段により前記残存電圧降下値が補正された場合は、補正後の前記残存電圧降下値を、前記推定電圧推定手段が推定した前記バッテリの推定電圧の値に加算することで、前記バッテリの現在の充電容量を演算する構成とした。
【０１５８】
このため、請求項１０に記載した本発明のバッテリ容量演算装置において、温度検出手段が検出したバッテリの周辺温度が変化してバッテリの容量が変化し、その容量に応じてバッテリの開回路電圧が、残存電圧降下値割出手段によって残存電圧降下値を求める際に用いる、開回路電圧値記憶手段に記憶されている開回路電圧に対して変化しても、補正手段により残存電圧降下値を補正することで温度補償して、現在のバッテリ周辺温度に応じたバッテリの現在の充電容量を精度良く演算することができる。
【０１５９】
また、請求項１２に記載した本発明のバッテリ容量演算装置によれば、請求項８、９、１０又は１１に記載した本発明のバッテリ容量演算装置において、少なくとも放電直前に前記バッテリに発生していた充電側分極を解消するのに十分な電流値が、前記車両のセルモータ始動時に必要とする所定の大電流値であり、前記放電電流減少開始検出手段は、前記バッテリの定負荷放電において、該バッテリの放電電流が前記所定の大電流値から減少し始めたことを検出するように構成されており、該所定の大電流値から減少し始めたことを前記放電電流減少開始検出手段が検出した前記バッテリの放電電流が、前記セルモータ以外の前記車両の負荷が駆動されている際における最大放電電流値以上の、目標電流値に低下したことを検出する放電電流低下検出手段をさらに備えており、前記特性割出手段が、前記バッテリの放電電流が前記所定の大電流値から減少し始めたことを前記放電電流減少開始検出手段が検出した後、前記目標電流値に低下したことを前記放電電流低下検出手段が検出するまでの間、前記周期的に測定される前記バッテリの端子電圧と放電電流とから前記電圧−電流特性を表わす式を求める構成とした。
【０１６０】
このため、請求項８、９、１０又は１１に記載した本発明のバッテリ容量演算装置において、セルモータ以外の車両の負荷が今なお駆動されているとしても、所定の大電流値による放電を行ったことによって発生した放電側分極による電圧降下のうち、バッテリの放電電流が所定の大電流値から減少し始めたことを放電電流減少開始検出手段が検出してから、放電電流が目標電流値に低下したことを放電電流低下検出手段が検出するまでの間に、その放電電流の低下によって解消した電圧降下分を除く残存成分のみを、純粋に反映したバッテリの端子電圧と放電電流とから、セルモータ以外の車両の負荷に対する電力供給による影響を排除した電圧−電流特性を表わす式と推定電圧とを、特性割出手段と推定電圧推定手段とにより求めて、バッテリの充電状態を精度良く演算することができる。
【図面の簡単な説明】
【図１】本発明のバッテリ容量演算装置の基本構成図である。
【図２】本発明のバッテリ容量演算方法を適用した本発明の一実施形態に係るバッテリ容量演算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】図２のマイクロコンピュータのＲＯＭに格納されている残存電圧降下値の補正データの一例を示すグラフである。
【図４】図２のマイクロコンピュータのＲＯＭに格納された制御プログラムに従いＣＰＵが行う処理のメインルーチンを示すフローチャートである。
【図５】図４の開回路電圧更新処理を示すサブルーチンのフローチャートである。
【図６】図４の充電状態演算処理を示すサブルーチンのフローチャートである。
【図７】図４の充電状態演算処理を示すサブルーチンのフローチャートである。
【図８】平衡状態のバッテリが行う定負荷放電における放電電流の増加時と減少時との一般的な電圧−電流特性差を示すグラフである。
【図９】図２のバッテリが平衡状態から行った２５０Ａの定負荷放電における放電電流の増加時と減少時との電圧−電流特性差を示すグラフである。
【図１０】平衡状態でないバッテリが行う定負荷放電における放電電流の増加時と減少時との一般的な電圧−電流特性差を示すグラフである。
【図１１】バッテリの定電流放電中にサンプリングした所定数の端子電圧及び放電電流の組に最小二乗法を適用して得られる、２次近似式で表したバッテリの電圧−電流特性の一例を示すグラフである。
【図１２】バッテリの定電流放電における端子電圧と放電時間との相関を示すグラフである。
【図１３】バッテリの定電流放電中にサンプリングした所定数の端子電圧及び放電電流の組と、これらに最小二乗法を適用して得られる直線的な電圧−電流特性式との関係を模式的に示すグラフである。
【図１４】図１３に示す電圧−電流特性から推定した推定電圧により得られる複数の定電流放電特性を示すグラフである。
【図１５】図１３に示す電圧−電流特性から推定した推定電圧により得られる複数の仮想上の定電流放電特性を示すグラフである。
【図１６】各容量に応じたバッテリの電圧−電流特性を同一平面上に展開したグラフである。
【図１７】図１５のグラフにおいて直線的特性を示す仮想上の放電電流値におけるバッテリの容量と図１３に示す電圧−電流特性から推定した推定電圧との関係を示すグラフである。
【図１８】バッテリの放電中に発生する電圧降下の内容を示すグラフである。
【符号の説明】
５ セルモータ
１３ バッテリ
１９ 温度検出手段
２３ マイクロコンピュータ
２３ａ ＣＰＵ
２３ｂ ＲＡＭ
２３ｃ ＲＯＭ
２３Ａ 特性割出手段
２３Ｂ 推定電圧推定手段
２３Ｃ 平衡状態判別手段
２３Ｄ 残存電圧降下値割出手段
２３Ｅ 開回路電圧更新手段
２３Ｆ 補正手段
２５ 開回路電圧値記憶手段
２７ 残存電圧降下値記憶手段
Ａ 放電電流減少開始検出手段
Ｂ 平衡状態端子電圧測定手段
Ｃ 放電電流低下検出手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for calculating a charging capacity of a battery that supplies power to a vehicle load, and more particularly, a voltage-current characteristic obtained from a battery terminal voltage and a discharge current measured periodically. The present invention relates to a method and apparatus for estimating an estimated voltage, which is an estimated terminal voltage in a constant load discharge state of a battery, and calculating a charge capacity of the battery using this estimated voltage.
[0002]
[Prior art]
Engines that use gasoline or light oil as the fuel are the mainstream propulsion drive sources in conventional vehicles, but in recent years, electric motors that do not directly discharge combustion gas have been used as the sole or auxiliary propulsion drive source. In vehicles equipped with such an electric motor, it is important to know the charge capacity of the battery that supplies power to the electric motor in order to determine the travelable distance, etc. .
[0003]
Therefore, the current integration method and the power integration method for obtaining the current charge capacity by subtracting the integrated power consumption calculated by using the integrated value of the discharge current from the full charge capacity of the battery are conventionally used. In the method, the original full charge capacity changes depending on the individual difference of the battery, the degree of progress of deterioration, and the like, and thus the current charge capacity of the battery cannot be accurately determined.
[0004]
In addition, since there is a certain linear correlation between the electrolyte specific gravity and the state of charge of the battery, it should be possible to grasp the state of charge of the battery by measuring the electrolyte specific gravity. In a battery that is being charged / discharged or just after the end of charge / discharge, the specific gravity of the electrolyte becomes uneven due to the chemical reaction that occurs between the electrolyte and the electrode. The state of charge of the battery cannot be accurately grasped.
[0005]
In addition, it is conceivable to measure the battery terminal voltage to determine the battery charge capacity, but the terminal voltage will not be stable unless the discharge current is stabilized. It cannot be expected from measurement.
[0006]
Moreover, as shown in the characteristic diagram of FIG. 12, when the battery is discharged at a constant current of 10 to 80 (A) in increments of 10 A, the discharge time (horizontal axis) and the terminal voltage of the battery (V: vertical axis) Is different from the point that the discharge time is longer as the discharge current is smaller, but is common in that the terminal voltage of the battery rapidly decreases as the discharge time elapses.
[0007]
Here, the horizontal axis of the characteristic diagram of FIG. 12 is time, but considering that it is constant current discharge and that the battery capacity is expressed in terms of electricity (Ah), this horizontal axis represents the battery capacity. You can think that it is good to see.
[0008]
Therefore, when the characteristic diagram of FIG. 12 is viewed as a correlation between the battery capacity on the horizontal axis and the terminal voltage on the vertical axis during constant current discharge, the smaller the discharge current, the larger power can be taken out, and the vertical axis side It can be seen that the capacity drop is slow in the vicinity of the fully charged state of the battery close to, and the capacity drops sharply as it moves away from the vertical axis to the right side in FIG.
[0009]
From the above, even if the discharge current can be stabilized, the charge capacity cannot be obtained from the battery terminal voltage because there is no linear correlation between the battery charge capacity and the terminal voltage. I understand that.
[0010]
Therefore, attention is paid to the relationship between the electrolyte specific gravity of the battery having a substantially linear correlation and the open circuit voltage (terminal voltage in the open circuit state of the battery in an equilibrium state), and the battery having the same linear correlation. This is a capacity calculation method that uses the relationship between the state of charge of the battery and the open circuit voltage, where a linear correlation should be established from the relationship between the electrolyte specific gravity and the state of charge.
[0011]
However, the only weakness of this capacity calculation method is that the open circuit voltage of the battery can be measured only during non-discharge when there is no change in charge state except for natural discharge, in other words, it changes to charge state. It is impossible to measure the open circuit voltage of the battery at the time of discharging.
[0012]
Therefore, the most important point in using the capacity calculation method using the relationship between the state of charge of the battery and the open circuit voltage is how to find the open circuit voltage when the battery is discharged.
[0013]
By the way, what can be measured at the time of battery discharge is the battery terminal voltage and discharge current. From the characteristic diagram of FIG. 12, the battery terminal voltage decreases if the discharge current increases even if the battery charge state does not change. Therefore, there is a voltage-current characteristic (IV characteristic) showing a negative correlation between the terminal voltage and the discharge current, and the voltage-current characteristic showing the negative correlation is It turns out that it changes when the state of charge changes.
[0014]
Therefore, in order to obtain a plurality of voltage-current characteristics of the battery according to the state of charge of the battery, the following measurement is performed.
[0015]
First, a certain current I _a And this current I _a Lower current I _b The battery is continuously discharged by a pulsed current that alternately appears periodically, and a set of battery terminal voltage and discharge current (I _a , V ₁ ), (I _b , V ₂ ), (I _a , V _Three ), (I _b , V _Four ,... Are sampled in a predetermined number (for example, 100 samples) continuously in synchronization with the pulse period (for example, 1 ms) of the discharge current.
[0016]
Then, a set of battery terminal voltage and discharge current (I _a , V ₀₁ ), (I _b , V ₀₂ ), (I _a , V ₀₃ ), (I _b , V ₀₄ ),... By the least square method, V = a ₁ I + b ₁ The coefficient a in the linear voltage-current characteristic equation of the battery ₁ , B ₁ To obtain this equation V = a ₁ I + b ₁ Is defined as the voltage-current characteristic of the battery corresponding to the capacity during the above sampling.
[0017]
Next, a pulse current I _a , I _a The battery terminal voltage and the discharge current (I) appearing in the opposite phase to the discharge current at that time. _a , V ₁₁ ), (I _b , V ₁₂ ), (I _a , V ₁₃ ), (I _b , V ₁₄ ),... Are continuously sampled, and from these, V = a by the least square method. ₂ I + b ₂ The coefficient a in the linear voltage-current characteristic equation of the battery ₂ , B ₂ To obtain this equation V = a ₂ I + b ₂ Is defined as the voltage-current characteristic of the battery corresponding to the capacity during the above sampling.
[0018]
Thereafter, in the same manner, V = a _n I + b _n The coefficient a in the linear voltage-current characteristic equation of the battery _n , B _n To obtain this equation V = a _n I + b _n Is defined as a voltage-current characteristic corresponding to different capacities of the battery that gradually decrease, thereby obtaining a voltage-current characteristic of the battery corresponding to each capacity from 100% to 0%.
[0019]
It should be noted that each predetermined number of samples of battery terminal voltage and discharge current (I _a , V _n1 ), (I _b , V _n2 ), (I _a , V _n3 ), (I _b , V _n4 ),..., And a linear voltage-current characteristic equation V = a obtained by applying the least square method thereto _n I + b _n The relationship between and is schematically shown in FIG.
[0020]
Here, the virtual current value Is, which is a virtual constant current value, is substituted into the voltage-current characteristic equation of the battery corresponding to each capacity obtained as described above, and V obtained thereby is determined as the constant load of the battery. When defined as an estimated voltage Vn that is an estimated terminal voltage in a discharged state, a constant current discharge characteristic as shown in the graph of FIG. 14 is obtained.
[0021]
Even if any positive value is substituted as the virtual current value Is, the constant current discharge characteristic by the virtual current value Is is estimated voltage as the capacity taken on the horizontal axis advances to the right side in FIG. It can be seen that the constant current discharge characteristic shows the same characteristic even in the case of the virtual current value Is = 0A which should theoretically indicate an open circuit voltage, in which Vn decreases rapidly.
[0022]
However, according to the graph of FIG. 14, the smaller the virtual current value Is, the smaller the degree that the estimated voltage Vn decreases as the capacity approaches 0. When a negative value is substituted as the virtual current value Is in the voltage-current characteristic equation of the battery corresponding to each capacity obtained in this way, and the constant current discharge characteristic by the negative virtual current value Is is shown in the graph. As shown in FIG. 15, in this case, the characteristic change of the estimated voltage Vn in the region close to the capacity 0 is changed with the virtual current value Is = −10 A as a boundary.
[0023]
Therefore, theoretically, assuming that the virtual current value Is is −10 A, the estimated voltage Vn in constant current discharge shows a linear characteristic with respect to the battery capacity.
[0024]
Therefore, in the graph of FIG. 16, the voltage-current characteristics of the battery corresponding to each capacity obtained as described above are developed on the same plane with the discharge current I on the vertical axis and the terminal voltage V on the horizontal axis. Let us verify that the estimated voltage Vn in constant current discharge exhibits a linear characteristic with respect to the capacity of the battery.
[0025]
First, a coefficient a representing the slope of each voltage-current characteristic equation ₁ , A ₂ , ..., a _n Are different from each other, and the coefficient b representing the intercept of each voltage-current characteristic equation ₁ , B ₂ , ..., b _n Therefore, in the positive discharge current region that actually exists in FIG. 16, there is no discharge current value I in which the terminal voltage V changes linearly with respect to the change in battery capacity.
[0026]
However, in the negative discharge current region, which is an imaginary region in FIG. 16, the terminal voltage V changes linearly with respect to the battery capacity when the discharge current value is I = −10 A. Thus, the terminal voltage V of the battery corresponding to each capacity at the discharge current value I = −10 A is the estimated voltage Vn.
[0027]
Therefore, when the relationship between the battery capacity at the virtual current value Is = −10 A and the estimated voltage Vn having a linear correlation with the virtual current value Is = −10 A is shown in a graph, as shown in FIG. The estimated voltage Vn exists between the open circuit voltage Vs of the battery and the open circuit voltage Ve at the end of discharge, and the value on the capacity on the horizontal axis corresponding to the estimated voltage Vn is the remaining capacity of the battery, that is, That is, the state of charge (SOC).
[0028]
Therefore, it can be said that the estimated voltage Vn is an alternative to the open circuit voltage of the battery, and even during a discharge when the open circuit voltage cannot be measured, the discharge is a constant load discharge in which the load supplying power does not change during the discharge. If so, by measuring the battery terminal voltage and discharge current that fluctuate slightly during the discharge, find the voltage-current characteristics that are the correlation between the battery terminal voltage and the discharge current in the constant load discharge. Then, by substituting the virtual current value Is = −10 A into the characteristic equation (V = aI + b) to obtain the estimated voltage Vn, the state of charge SOC of the battery can be obtained from the estimated voltage Vn.
[0029]
Then, when converted to the ratio of the estimated voltage Vn on the vertical axis of FIG. 17 to the open circuit voltage Vs at the time of full charge, the current state of charge SOC with respect to the full charge capacity is obtained.
SOC = {(Vn−Ve) / (Vs−Ve)} × 100 (%)
It becomes.
[0030]
However, for the sake of accuracy, when converting the ratio of power (V × Ah) to obtain the current state of charge SOC for the full charge capacity,

It becomes.
[0031]
[Problems to be solved by the invention]
By the way, during battery discharge, as shown in FIG. 18, a voltage drop due to the effect of pure resistance (battery ohmic resistance), that is, an IR drop obtained by multiplying the pure resistance by the discharge current, or a voltage drop due to discharge side polarization. Conversely, while the battery is being charged, a voltage increase due to the effect of these pure resistances and a voltage increase due to charge side polarization occur.
[0032]
In particular, as shown in FIG. 18, the activation polarization for advancing the redox reaction on the surface of the electrode included in the discharge-side polarization that occurs during battery discharge, and the electrode surface and the solution bulk as a result of mass transfer. The concentration polarization due to the difference in concentration of reactants and products generated during the reaction does not show a linear correlation proportional to the value of the discharge current because it reacts with a slight delay with respect to the increase or decrease of the discharge current.
[0033]
Therefore, as described above, when the estimated voltage Vn is obtained instead of the open circuit voltage of the battery that cannot be measured at the time of discharge in order to obtain the state of charge SOC of the battery, the terminal voltage and the discharge current are being discharged as the preceding stage. When the voltage-current characteristics of the battery are determined by measuring the voltage, the terminal voltage includes a voltage drop due to polarization at the time of discharge. Therefore, the estimated voltage-current characteristics of the battery and the estimation estimated from the voltage-current characteristics The voltage Vn reflects not only the state of charge SOC of the battery but also a voltage drop due to polarization. Therefore, if the estimated voltage Vn is used as it is, the state of charge SOC of the battery cannot be accurately obtained. .
[0034]
The present invention has been made in view of the above circumstances, and an object of the present invention is an estimated terminal voltage in a constant load discharge state of a battery, which is obtained from a correlation between a battery terminal voltage and a discharge current that can be measured during discharging. When the estimated voltage is used to determine the state of charge of the battery, the terminal voltage of the battery being discharged used to determine the estimated voltage is not completely eliminated from the voltage rise or voltage drop due to the previous charge or discharge Even in such a case, it is an object of the present invention to provide a battery capacity calculation method capable of accurately calculating the state of charge of the battery and a battery capacity calculation device suitable for use in carrying out this method.
[0035]
[Means for Solving the Problems]
The present invention according to claims 1 to 6 that achieves the above object relates to a battery capacity calculation method, and the present invention according to claims 7 to 12 relates to a battery capacity calculation device.
[0036]
The battery capacity calculation method according to the first aspect of the present invention periodically measures the terminal voltage and the discharge current of the battery that supplies power to the vehicle load, and shows the correlation between the terminal voltage and the discharge current. A voltage-current characteristic is obtained, an estimated voltage that is an estimated terminal voltage in a constant load discharge state of the battery is estimated using the voltage-current characteristic, and a charge capacity of the battery is calculated using the estimated voltage. Hitting Based on an expression representing the voltage-current characteristics of the battery in various charge capacities, a current value giving a voltage that linearly changes in response to the change in the charge capacity is obtained in advance as a virtual current value, A voltage-current characteristic is obtained while the discharge current of the constant load discharge by the battery in the equilibrium state is decreased from a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge. Expression In The current that gives the estimated voltage, which is a voltage that changes linearly in response to the change in the charge capacity, obtained in advance based on the expression representing the voltage-current characteristics of the battery at various charge capacities, is used as the virtual current value. Substitute The estimated value of the estimated voltage of the battery at the time of constant load discharge with the predetermined large current value, and the state of the battery in the equilibrium state before the start of the constant load discharge used to estimate the value of the estimated voltage A difference value from the value of the open circuit voltage, which is a terminal voltage, is obtained in advance as a residual voltage drop value that is a residual voltage drop amount due to the influence of residual polarization at the end of discharge of the battery. The battery terminal voltage and discharge current measured periodically during the constant load discharge every time constant load discharge is performed with a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge. Voltage-current characteristics from Represents the expression Find this voltage-current characteristic Substituting the virtual current value into the expression for The current estimated voltage of the battery is estimated, and the current charge capacity of the battery is calculated by adding the remaining voltage drop value to the estimated current voltage value of the battery. It is characterized by that.
[0037]
The battery capacity calculation method of the present invention described in claim 2 is the battery capacity calculation method of the present invention described in claim 1, wherein the value of the terminal voltage of the battery in an equilibrium state is measured in advance and the measured value is measured. Is set to the value of the open circuit voltage, and following the setting of the open circuit voltage, the battery in an equilibrium state is sufficient to eliminate at least the charge side polarization generated in the battery immediately before discharging. When performing constant load discharge to a current value, periodically measured while the discharge current of the constant load discharge decreases from the maximum current value, from the terminal voltage and discharge current of the battery, An expression representing the voltage-current characteristic is obtained, and the virtual current value is substituted into the expression representing the voltage-current characteristic. Estimating the estimated voltage of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery at least immediately before the discharge from the equilibrium state, and the estimated battery The residual voltage drop value is obtained in advance by subtracting the estimated voltage value from the set open circuit voltage value.
[0038]
Furthermore, the battery capacity calculation method of the present invention described in claim 3 is the battery capacity calculation method of the present invention described in claim 2, wherein the value of the open circuit voltage is calculated each time the battery is in an equilibrium state. The battery terminal voltage value measured in the equilibrium state is updated and set.
[0039]
The battery capacity calculation method of the present invention described in claim 4 is the battery capacity calculation method of the present invention described in claim 1, 2, or 3, wherein the battery is generated in the battery at least immediately before discharging. Every time constant load discharge is performed with a current value sufficient to eliminate the charged side polarization, the terminal voltage of the battery is periodically measured while the discharge current of the constant load discharge decreases from the maximum current value. From the discharge current, the voltage-current characteristics Represents the expression The voltage-current characteristics Substituting the virtual current value into the expression The current estimated voltage of the battery is estimated.
[0040]
Furthermore, the battery capacity calculation method of the present invention described in claim 5 is the battery capacity calculation method of the present invention described in claim 1, 2, 3 or 4, wherein the charge generated in the battery at least immediately before the discharge is performed. A current value sufficient to eliminate side polarization is set to a predetermined large current value required when starting the cell motor of the vehicle, and the battery discharge current value starts to decrease from the predetermined large current value. Measured periodically during a period lower than a predetermined large current value and lower than a maximum discharge current value when the load of the vehicle other than the cell motor is being driven, to a target current value. A voltage-current characteristic used to estimate an estimated voltage of the battery at a constant load discharge with the predetermined large current value from a terminal voltage of the battery and a discharge current. Represents the expression I asked for it.
[0041]
Further, the battery capacity calculation method of the present invention described in claim 6 is the battery capacity calculation method of the present invention described in claim 1, 2, 3, 4 or 5, and is generated in the battery 13 at least immediately before discharging. Each time the estimated voltage of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization that has been present is estimated, the ambient temperature of the battery at the estimated time and the open circuit voltage are obtained The difference between the temperature of the battery and the ambient temperature of the battery is confirmed, and if there is a difference, the residual voltage drop value is corrected according to the temperature difference, and the battery voltage is corrected using the corrected residual voltage drop value. The current charge capacity was calculated.
[0042]
Further, the battery capacity calculation device according to the present invention described in claim 7 is generated in the battery 13 at least immediately before discharging, as shown in the basic configuration diagram of FIG. At the time of constant load discharge with a current value sufficient to eliminate the charge-side polarization, the terminal voltage and discharge current of the battery 13 at the time of constant load discharge are periodically measured, and the terminal voltage and discharge current are Voltage-current characteristics showing correlation Represents the expression The voltage-current characteristics Represents the expression An estimated voltage that is an estimated terminal voltage in the constant load discharge state of the battery 13 using the estimated voltage, and a battery 13 capacity calculation device that calculates the charge capacity of the battery 13 using the estimated voltage. The voltage-current characteristics while the discharge current of the constant load discharge by the battery 13 is decreasing from a current value sufficient to eliminate the charge side polarization generated in the battery 13 at least immediately before the discharge. Expression In A current that gives an estimated voltage, which is a voltage that changes linearly with respect to the change in the charge capacity, obtained in advance based on an expression representing the voltage-current characteristics of the battery 13 in various charge capacities, is a virtual current. Substituting as a value Estimate the estimated voltage value of the battery 13 and the estimated voltage value at the time of constant load discharge with a current value sufficient to eliminate the charge-side polarization generated in the battery 13 at least immediately before the discharge. The difference value from the value of the open circuit voltage, which is the terminal voltage of the battery 13 in an equilibrium state before the start of the constant load discharge used to perform the residual voltage due to the influence of the residual polarization at the end of the discharge of the battery 13 A residual voltage drop value storage means 27 for storing a residual voltage drop value as a drop amount is provided, and the estimated voltage of the battery 13 estimated from the residual voltage drop value stored in the residual voltage drop value storage means is provided. The current charging capacity of the battery 13 is calculated by adding to the above value.
[0043]
Further, the battery capacity calculation device of the present invention described in claim 8 is the battery capacity calculation device of the present invention described in claim 7, which eliminates the charge-side polarization occurring in the battery 13 at least immediately before discharging. Discharge current decrease start detecting means A for detecting that the discharge current of the battery 13 starts to decrease from the maximum current value in the constant load discharge of the battery 13 with a current value sufficient for the discharge current, and the discharge current of the battery 13 After the discharge current decrease start detecting means A detects that the current starts to decrease from the maximum current value, the voltage-current characteristic is obtained from the terminal voltage and the discharge current of the battery 13 measured periodically. Represents the expression The characteristic indexing means 23A to be obtained and the voltage-current characteristics obtained by the characteristic indexing means 23A Represents the expression And an estimated voltage estimating means 23B for estimating an estimated voltage of the battery 13 at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization occurring in the battery 13 at least immediately before the discharge. And adding the residual voltage drop value stored in the residual voltage drop value storage means 27 to the estimated voltage value of the battery 13 estimated by the estimated voltage estimation means 23B. The current charge capacity was calculated.
[0044]
Furthermore, the battery capacity calculation device of the present invention described in claim 9 is the battery capacity calculation device of the present invention described in claim 8, wherein the open circuit voltage value storage means 25 stores the value of the open circuit voltage; An equilibrium state determination unit 23C that determines whether or not the battery 13 is in an equilibrium state, and the battery 13 that has been determined to be in an equilibrium state by the equilibrium state determination unit 23C at least immediately before the battery 13 is discharged. The estimated voltage value of the battery 13 estimated by the estimated voltage estimation means 23B is stored in the open circuit voltage value storage means 25 at the time of constant load discharge with a current value sufficient to eliminate the generated charge side polarization. A residual voltage drop value calculating means 23D for subtracting the stored open circuit voltage value to obtain the residual voltage drop value;憶 means 27 was assumed to the residual voltage drop value indexing means 23D stores the remaining voltage drop values determined.
[0045]
Further, the battery capacity calculation device of the present invention described in claim 10 is the battery capacity calculation device of the present invention described in claim 9, wherein the balance state determination means 23C determines that the battery is in an equilibrium state. The balanced state terminal voltage measuring means B for measuring the terminal voltage of the battery 13 and the battery in which the balanced state terminal voltage measuring means B measures the value of the open circuit voltage stored in the open circuit voltage value storage means 25. It is assumed that the apparatus further includes open circuit voltage updating means 23E for updating to the value of 13 terminal voltages.
[0046]
Furthermore, the battery capacity calculation device of the present invention described in claim 11 is the battery capacity calculation device of the present invention described in claim 10, wherein the temperature detection means 19 for detecting the ambient temperature of the battery 13 and the battery 13 When the estimated voltage estimation means 23B estimates the estimated voltage of the battery 13, the equilibrium terminal voltage measurement means B measures the ambient temperature of the battery 13 detected by the temperature detection means 19 and the terminal voltage of the battery 13. At the time, whether there is a difference with the ambient temperature of the battery 13 detected by the temperature detection means 19 is checked, and if there is a difference, it is stored in the residual voltage drop value storage means 27 according to the temperature difference. Correction means 23F for correcting the residual voltage drop value, and the residual voltage drop value is corrected by the correction means 23F. In this case, the current charge capacity of the battery 13 is calculated by adding the corrected residual voltage drop value to the estimated voltage value of the battery 13 estimated by the estimated voltage estimation means 23B. .
[0047]
A battery capacity calculation apparatus according to a twelfth aspect of the present invention is the battery capacity calculation apparatus according to the eighth, ninth, tenth or eleventh aspect of the present invention. The current value sufficient to eliminate the side polarization is a predetermined large current value required at the time of starting the cell motor of the vehicle, and the discharge current decrease start detecting means detects the battery in constant load discharge of the battery. The battery is configured to detect that the discharge current starts to decrease from the predetermined large current value, and the battery in which the discharge current decrease start detecting means detects that the discharge current starts to decrease from the predetermined large current value. Discharge current reduction that detects that the discharge current of the vehicle has decreased to a target current value that is greater than or equal to the maximum discharge current value when the vehicle load other than the cell motor is being driven And a target current value after the discharge current decrease start detecting means detects that the discharge current of the battery has started to decrease from the predetermined large current value. The voltage-current characteristic is calculated from the terminal voltage and discharge current of the battery measured periodically until the discharge current drop detecting means detects Represents the expression Wanted
[0048]
According to the battery capacity calculation method of the present invention described in claim 1, the discharge current of the constant load discharge performed by the battery is a current value sufficient to eliminate at least the charge-side polarization generated in the battery immediately before the discharge. If the voltage drop or voltage rise due to the polarization on the discharge side or the charge side that occurred in the previous discharge remains before the start of discharge, it exceeds the remaining voltage drop and is large according to the discharge current value. The discharge side polarization is generated, or the remaining voltage rise is eliminated, and the discharge side polarization having a magnitude corresponding to the discharge current value is newly generated.
[0049]
On the other hand, even if a battery in an equilibrium state performs constant load discharge with a current value sufficient to eliminate the charge-side polarization that occurred in the battery at least immediately before the discharge, The discharge side polarization having a magnitude corresponding to the current value is generated.
[0050]
Therefore, if the battery performs a constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery immediately before the discharge, whether the battery was in an equilibrium state before the start of the constant load discharge, Or at least to eliminate the charge-side polarization that occurred in the battery just before the discharge, regardless of whether the discharge-side or charge-side polarization state that occurred in the previous discharge was not completely eliminated. The voltage-current characteristics obtained from the battery terminal voltage and discharge current while the discharge current is decreasing from a sufficient current value Expression The estimated voltage of the battery estimated by is the same value.
[0051]
Regardless of whether or not the battery is in an equilibrium state before the start of constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery at least immediately before the discharge, the constant load discharge is discharged to the battery. The estimated voltage value estimated after the start of is at least relative to the open circuit voltage corresponding to the terminal voltage of the battery in the equilibrium state, assuming that the battery before starting the constant load discharge was in an equilibrium state. Residual voltage determined in advance as the amount of residual voltage drop due to the effect of residual polarization at the end of constant-load discharge performed by the battery with a current value sufficient to eliminate the charge-side polarization that occurred in the battery immediately before discharge The lower value is shown by the amount of the drop value.
[0052]
Further, according to the battery capacity calculation method of the present invention described in claim 2, in the battery capacity calculation method of the present invention described in claim 1, the battery in the equilibrium state is generated in the battery at least immediately before the discharge. When a constant load discharge with a current value sufficient to eliminate charge side polarization is performed, the open circuit voltage value is set by first measuring the value of the battery terminal voltage before the start of the constant load discharge. If the discharge current value of constant load discharge decreases from the current value sufficient to eliminate the charge side polarization that occurred in the battery immediately before discharge, the battery terminal voltage and discharge current measured periodically Voltage-current characteristics obtained from Substituting a virtual current value into the expression for The estimated voltage is estimated, and the difference between this estimated voltage value and the previously set open circuit voltage value is obtained as the residual voltage drop value. Thereafter, the current charge capacity of the battery is calculated. To be added to the current estimated voltage of the battery, which is estimated every time the battery performs constant load discharge.
[0053]
Furthermore, according to the battery capacity calculation method of the present invention as set forth in claim 3, in the battery capacity calculation method of the present invention as set forth in claim 2, the open circuit of the battery that changes in accordance with the change in the state of charge accompanying discharge The voltage is updated to the latest terminal voltage value every time the battery is in an equilibrium state.
[0054]
According to the battery capacity calculation method of the present invention described in claim 4, in the battery capacity calculation method of the present invention described in claim 1, 2, or 3, the battery is generated in the battery at least immediately before discharging. Each time a constant load discharge is performed with a current value sufficient to eliminate the charged side polarization, the battery terminal voltage and discharge current measured periodically while the discharge current value decreases from the maximum current value Voltage-current characteristics obtained from Substituting the virtual current value into the expression for Thus, the current estimated voltage of the battery is estimated, and the current state of charge of the battery is calculated from the estimated voltage value and the remaining voltage drop value.
[0055]
Furthermore, according to the battery capacity calculation method of the present invention described in claim 5, in the battery capacity calculation method of the present invention described in claim 1, 2, 3 or 4, a predetermined amount required when starting the cell motor of the vehicle. The large current value exceeds the current value in that case even if a plurality of electric powers from the battery are simultaneously supplied to other loads of the vehicle. Is set to a current value sufficient to eliminate the charge-side polarization that occurred in the battery immediately before discharge, so that when the discharge current reaches a predetermined large current value, the previous discharge This leads to a state where a voltage drop exceeding the voltage drop due to the discharge-side polarization generated by is generated in the battery terminal voltage.
[0056]
On the other hand, if the discharge current value of the battery decreases from a predetermined large current value and falls to a target current value that is equal to or greater than the maximum discharge current value when a vehicle load other than the cell motor is being driven, the battery terminal in that state In the voltage drop due to the discharge side polarization remaining in the voltage, the voltage drop component due to the discharge side polarization generated by supplying electric power to the vehicle load other than the cell motor does not appear on the surface, and the discharge due to a predetermined large current value Only the remaining components of the voltage drop caused by the discharge-side polarization generated by performing the above steps except for the amount eliminated by the discharge current being reduced to the target current value will appear on the surface.
[0057]
Therefore, the terminal voltage and discharge measured periodically until the discharge current value of the battery that has been subjected to constant load discharge with a predetermined large current value decreases from the predetermined large current value to the target current value. Battery voltage-current characteristics Represents the expression To obtain this voltage-current characteristic. Substituting the virtual current value into the expression The estimated voltage is the target current value of the voltage drop due to the discharge-side polarization generated by discharging with a predetermined large current value, even if the vehicle load other than the cell motor is still driven. Therefore, only the remaining components excluding the portion eliminated by the decrease in the amount of pure water are reflected purely.
[0058]
Moreover, according to the battery capacity calculation method of the present invention described in claim 6, in the battery capacity calculation method of the present invention described in claim 1, 2, 3, 4 or 5, when the ambient temperature of the battery changes, Since the battery voltage changes and the terminal voltage that appears at the battery terminal also changes, it eliminates the charge-side polarization that occurred in the battery at the time when the open circuit voltage of the battery in the equilibrium state was obtained and at least immediately before the discharge. If the battery ambient temperature differs at the estimated time of the estimated battery voltage during constant load discharge with a sufficient current value, the terminal voltage component reflected in the open circuit voltage according to the battery ambient temperature, and the battery The terminal voltage component reflected in the estimated voltage differs depending on the ambient temperature.
[0059]
However, the battery at the time of constant load discharge with the battery ambient temperature at the time of obtaining the open circuit voltage of the battery in an equilibrium state and at least a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge When the current charge capacity of the battery is calculated using the corrected remaining voltage drop value corrected according to the ambient temperature of the battery at the estimated time of the estimated voltage, the terminal voltage component corresponding to the ambient temperature of the battery is calculated. Using the open circuit voltage and the estimated voltage reflected under the same conditions, the current charge state of the battery is calculated in a state in which the fluctuation component of the terminal voltage due to the difference in the ambient temperature of the battery is eliminated.
[0060]
Furthermore, according to the battery capacity calculation apparatus of the present invention as set forth in claim 7, as shown in FIG. 1, the charge current generated by the battery 13 at the constant load discharge is charged at least immediately before the battery 13 is discharged. When a current value sufficient to eliminate the side polarization is reached, even if a voltage drop or voltage increase due to polarization on the discharge side or charge side that occurred in the previous discharge remains before the start of the discharge, the remaining voltage The discharge side polarization with the magnitude corresponding to the discharge current value exceeding the drop is generated, or after the remaining voltage rise is resolved, the discharge side polarization with the magnitude corresponding to the discharge current value is newly added. Will occur.
[0061]
On the other hand, even if the battery 13 in an equilibrium state performs a constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery 13 at least immediately before the discharge, when the discharge current value is reached, The discharge side polarization having a magnitude corresponding to the discharge current value is generated.
[0062]
Therefore, when the battery 13 performs a constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery 13 at least immediately before the discharge, the battery 13 is in an equilibrium state before the start of the constant load discharge. Or at least the charge side polarization generated in the battery 13 immediately before the discharge, regardless of whether the polarization state on the discharge side or the charge side generated in the previous discharge was not completely eliminated. Voltage-current characteristics obtained from the terminal voltage of the battery 13 and the discharge current while the discharge current is decreasing from the current value sufficient to eliminate Expression The estimated voltage of the battery 13 estimated by the above is the same value.
[0063]
The constant load discharge is performed regardless of whether or not the battery 13 is in an equilibrium state before the start of the constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery 13 at least immediately before the discharge. The estimated voltage value estimated after the battery 13 is started is the open circuit voltage corresponding to the terminal voltage of the battery 13 in the equilibrium state when the battery 13 before starting the constant load discharge is assumed to be in the equilibrium state. On the other hand, as a residual voltage drop due to the influence of the residual polarization at the end of the constant load discharge performed by the battery 13 with a current value sufficient to eliminate the charge side polarization generated in the battery 13 at least immediately before the discharge The lower value is obtained by the amount of the remaining voltage drop value obtained in advance and stored in the remaining voltage drop value storage means 27.
[0064]
According to the battery capacity calculation device of the present invention described in claim 8, in the battery capacity calculation device of the present invention described in claim 7, the battery 13 is charged at least immediately before discharging. When a constant load discharge is performed with a current value sufficient to eliminate the side polarization, the discharge current decrease start detecting means A detects that the discharge current of the battery 13 starts to decrease from the maximum current value. A voltage-current characteristic is obtained from the terminal voltage and discharge current of the battery 13 measured periodically while the value decreases from the maximum current value. Expression Is obtained by the characteristic indexing means 23A, and the voltage-current characteristic obtained by the characteristic indexing means 23A is obtained. Substituting the virtual current value into the expression The estimated voltage estimation means 23B estimates the estimated voltage of the battery 13 at the time of constant load discharge with a current value sufficient to eliminate the charging side polarization occurring in the battery 13 at least immediately before the discharge, and this estimated voltage estimation means The current charging state of the battery 13 is calculated from the estimated voltage value estimated by 23B and the remaining voltage drop value stored in the remaining voltage drop value storage means 27.
[0065]
Further, according to the battery capacity calculation device of the present invention as set forth in claim 9, in the battery capacity calculation device of the present invention as set forth in claim 8, the battery 13 determined as being in an equilibrium state by the equilibrium state determination means 23C. However, if a constant load discharge is performed at a current value sufficient to eliminate the charge-side polarization that has occurred in the battery 13 at least immediately before the discharge, the discharge voltage of the battery 13 is maximized by the residual voltage drop value indexing means 23D. The open circuit voltage stored in the open circuit voltage value storage unit 25 is the estimated voltage value estimated by the estimated voltage estimation unit 23B after the discharge current decrease start detection unit A detects that the current starts to decrease. The residual voltage drop value is obtained by subtracting from this value, and the obtained residual voltage drop value is stored in the residual voltage drop value storage means 27.
[0066]
According to the battery capacity calculation device of the present invention described in claim 10, in the battery capacity calculation device of the present invention described in claim 9, the open circuit voltage of the battery 13 according to the change in the state of charge accompanying discharge. When the battery 13 is in an equilibrium state even if the battery voltage is changed, the value of the open circuit voltage stored in the open circuit voltage value storage means 25 is determined as the equilibrium state terminal voltage measurement means every time it is determined by the equilibrium state determination means 23C. The terminal voltage of the battery 13 in the equilibrium state measured by B is updated to the latest value.
[0067]
Furthermore, according to the battery capacity calculation device of the present invention described in claim 11, in the battery capacity calculation device of the present invention described in claim 10, when the ambient temperature of the battery 13 changes, the capacity of the battery 13 changes. Since the terminal voltage appearing at the terminal of the battery 13 also changes, the battery 13 determined to be in an equilibrium state by the time when the open circuit voltage stored in the open circuit voltage value storage means 25 is obtained and the equilibrium state determination means 23C. After the discharge current decrease start detection means A detects that the discharge current of the battery has started to decrease from a predetermined large current value, the temperature detection means 19 starts when the estimated voltage estimation means 23B estimates the estimated voltage of the battery 13. When the ambient temperature detected by the battery 13 is different, the terminal voltage component reflected in the open circuit voltage according to the ambient temperature of the battery 13 and the battery 13 and the terminal voltage component reflected in the estimated voltage according to the ambient temperature of, will differ each.
[0068]
However, when the open circuit voltage stored in the open circuit voltage value storage means 25 is obtained, the ambient temperature of the battery 13 detected by the temperature detection means 19 and the equilibrium state determination means 23C are determined to be in an equilibrium state. After the discharge current decrease start detecting means A detects that the discharge current of the battery 13 has started to decrease from a current value sufficient to eliminate the charge side polarization generated in the battery 13 at least immediately before discharging, the battery Even if the ambient temperature of the battery 13 detected by the temperature detection means 19 is different from each other when the estimated voltage estimation means 23B estimates the estimated voltage 13, the remaining voltage stored in the residual voltage drop value storage means 27. The voltage drop value is corrected by the correcting means 23F according to both ambient temperatures, and the battery voltage is calculated using the remaining voltage drop value after being corrected by the correcting means 23F. 13 by calculating the current charging capacity of the battery 13 by using the open circuit voltage and the estimated voltage in which the terminal voltage component corresponding to the ambient temperature of the battery 13 is reflected under the same condition, The current charging state of the battery 13 is calculated in a state where the voltage fluctuation component is eliminated.
[0069]
According to the battery capacity calculation device of the present invention described in claim 12, in the battery capacity calculation device of the present invention described in claim 8, 9, 10 or 11, the predetermined required at the start of the vehicle cell motor 5 The large current value exceeds the current value even when a plurality of electric powers from the battery 13 are simultaneously supplied to other loads of the vehicle. Is set to a current value sufficient for polarization on the charge side generated in the battery 13 immediately before discharging, so that the discharge current of the constant load discharge by the battery 13 is increased from the maximum current value. When the discharge current decrease start detecting means A detects that the discharge has started to decrease, the discharge current once reached a predetermined large current value before that, and the discharge side polarization generated by the previous discharge Voltage drop exceeding the voltage drop due is to have reached the state of being generated on the terminal voltage of the battery 13.
[0070]
Then, the discharge current value is reduced when the discharge current value of the battery 13 is decreased from a predetermined large current value and the target current value is not less than the maximum discharge current value when the vehicle load other than the cell motor 5 is being driven. When the detection means C detects, the voltage drop due to the discharge side polarization remaining in the terminal voltage of the battery 13 in that state causes the discharge side polarization generated by supplying power to the vehicle load other than the cell motor 5. The voltage drop component due to the discharge does not appear on the surface, and the remaining component excluding the portion of the voltage drop caused by the discharge-side polarization generated by performing the discharge with a predetermined large current value, which is eliminated by the discharge current decreasing to the target current value Only the state of appearance on the surface is reached.
[0071]
Accordingly, after the discharge current decrease start detecting means A detects that the discharge current of the battery 13 has started to decrease from a predetermined large current value, until the discharge current decrease detecting means C detects that the discharge current has decreased to the target current value. The characteristic indexing means 23A determines the voltage-current characteristics of the battery 13 from the terminal voltage and the discharge current measured periodically. Represents the expression Finding this voltage-current characteristic Substituting the virtual current value into the expression The estimated voltage estimated by the estimated voltage estimating means 23B is a voltage drop caused by the discharge-side polarization generated by discharging with a predetermined large current value even if the vehicle load other than the cell motor 5 is still driven. Thus, only the remaining components excluding the amount eliminated by the reduction of the discharge current to the target current value are reflected purely.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a battery capacity calculation method according to the present invention will be described together with a battery capacity calculation apparatus according to the present invention with reference to the drawings.
[0073]
FIG. 2 is an explanatory diagram showing, in partial block form, a schematic configuration of a battery capacity calculation apparatus according to an embodiment of the present invention to which the battery capacity calculation method of the present invention is applied. This embodiment indicated by reference numeral 1 in FIG. The battery capacity calculation device according to the embodiment is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3.
[0074]
In this hybrid vehicle, normally, only the output of the engine 3 is transmitted from the drive shaft 7 to the wheels 11 through the differential case 9 and travels. When the load is high, the motor generator 5 is driven by the electric power from the battery 13. In addition to the output of the engine 3, the output of the motor generator 5 is transmitted from the drive shaft 7 to the wheels 11 to perform assist traveling.
[0075]
In addition, this hybrid vehicle is configured to cause the motor generator 5 to function as a generator (generator) during deceleration or braking and to convert the kinetic energy into electric energy to charge the battery 13.
[0076]
The motor generator 5 is further used as a cell motor that forcibly rotates the flywheel of the engine 3 when the engine 3 is started when a starter switch (not shown) is turned on. More electric power is consumed independently than when a plurality of other electric loads mounted on the vehicle are operating simultaneously.
[0077]
Incidentally, in the hybrid vehicle of this embodiment, although the starter switch is off, an accessory switch (not shown), an ignition switch, or a switch (not shown) for electrical components (loads) other than the motor generator 5 is on. For this reason, when an air conditioner, an audio device, a power window, a headlight, a room lamp (not shown), etc. are operating, the discharge current flowing from the battery 13 has a plurality of electrical components at the same time. Even if it is operating, it is less than 35A (ampere).
[0078]
Conversely, when the accessory switch is turned on and then the starter switch is turned on to operate the motor generator 5 as a cell motor in order to start the engine 3, no other electrical components are operating. However, a discharge current that reaches approximately 250 A (amperes) instantaneously flows from the battery 9.
[0079]
Therefore, in the battery capacity calculation device 1 of the present embodiment, whether or not the discharge current of the battery 13 is between the target current value = 35 A (lower limit) and the maximum current value = 250 A (upper limit) It becomes a standard for recognizing that constant load discharge for operating as a cell motor is performed.
[0080]
When the engine 3 is started by the motor generator 5 by turning on the starter switch, the starter switch is turned off and the ignition switch and the accessory switch are turned on with the release of the operation of the ignition key (not shown). Transition.
[0081]
Returning to the description of the configuration, the battery capacity calculation device 1 of the present embodiment calculates the state of charge of the battery 13 described above, and the electrical components such as a motor generator 5 that functions as a motor for assist travel and a cell motor. The battery 13 has a discharge current I of the battery 13 and a current sensor 15 for detecting a charging current for the battery 13 from the motor generator 5 functioning as a generator, and an infinite resistance connected in parallel to the battery 13, and the terminal voltage V of the battery 13 And a temperature sensor 19 (corresponding to temperature detecting means) for detecting a temperature h of an engine room (not shown) in which the engine 3 is arranged.
[0082]
Further, in the battery capacity calculation device 1 of the present embodiment, the outputs of the current sensor 15, the voltage sensor 17, and the temperature sensor 19 described above are A / in the interface circuit (hereinafter abbreviated as “I / F”) 21. A microcomputer (hereinafter abbreviated as “microcomputer”) 23 to be taken in after D conversion, and nonvolatile memories (hereinafter abbreviated as “NVM”) 25 and 27 connected to the microcomputer 23 are further provided. Yes.
[0083]
The microcomputer 23 includes a CPU 23a, a RAM 23b, and a ROM 23c. Among these, the CPU 23a is connected to the I / F 21 and the NVMs 25 and 27 in addition to the RAM 23b and the ROM 23c. The above-described starter switch (not shown), ignition switch, accessory switch, switches for electrical components (loads) other than the motor generator 5 and the like are further connected.
[0084]
The RAM 23b has a data area for storing various data and a work area used for various processing operations. The ROM 23c has a control program for causing the CPU 23a to perform various processing operations, and the NVM 25 stores the battery 13. Battery 13 itself or ambient temperature h at which open circuit voltage OCV is stored and stored ₁ And the temperature h of the battery 13 itself or the surroundings at the estimated time of the estimated voltage Vn, which is the estimated terminal voltage V in the constant load discharge state, estimated by the processing described later. ₂ In accordance with the residual voltage drop value e stored and stored in the NVM 27. ₀ And correction data for correcting.
[0085]
The residual voltage drop value e stored in the ROM 23c ₀ As shown in the graph of FIG. 3, the correction data represents a correction coefficient at each temperature from 0 ° C. to 55 ° C. when the correction coefficient at a temperature of 0 ° C. is “1”. In other words, it is like a table of temperature vs. correction coefficient.
[0086]
In the NVM 25 (corresponding to the open circuit voltage value storage means), the equilibrium state of the battery 13 that changes in accordance with the change of the charge capacity, that is, the voltage rise and voltage drop due to the polarization at the time of charge / discharge are completely eliminated. The terminal voltage V in the state where it does not remain is stored and stored as the open circuit voltage OCV of the battery 13, and the temperature of the engine room detected by the temperature sensor 19 at the time when the open circuit voltage OCV is stored and stored is Battery 13 itself or ambient temperature h ₁ Stored and stored as
[0087]
Note that, at the initial time when the hybrid vehicle was manufactured, the terminal voltage V of the battery 13 separately measured at the time of mounting is stored and stored in advance in the NVM 25 as the open circuit voltage OCV, and the open circuit voltage OCV is stored. The temperature of the battery 13 itself or the ambient temperature at the time of storage is the temperature of the battery 13 itself or the ambient temperature h. ₁ As stored in advance in the NVM 25.
[0088]
In the NVM 27 (corresponding to the residual voltage drop value storage means), when the battery 13 instantaneously performs a constant load discharge in order to start the engine 3 by the motor generator 5 when an ignition switch (not shown) is turned on. Further, in the constant load discharge state, which is estimated by the processing described later, based on the correlation between the terminal voltage V of the battery 13 and the discharge current I detected by the current sensor 15 or the voltage sensor 17 during the constant load discharge. The estimated voltage Vn, which is the estimated terminal voltage V, is the residual voltage drop due to the effect of the residual polarization at the end of the discharge of the battery 13, subtracted from the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 Residual voltage drop value e ₀ Is stored and stored.
[0089]
Note that the outputs of the current sensor 15, voltage sensor 17, and temperature sensor 19 described above are always taken into the CPU 23 a of the microcomputer 23 via the I / F 21.
[0090]
Next, processing performed by the CPU 23a according to the control program stored in the ROM 23c will be described with reference to the flowcharts of FIGS.
[0091]
When the microcomputer 23 is activated by the power supply from the battery 13 and the program is started, the CPU 23a first performs initialization as shown in the flowchart of the main routine in FIG. 4 (step S1).
[0092]
In the initial setting in step S1, a flag in the flag area provided in the work area of the RAM 23b is reset, a timer area is reset to zero, and a time count is started.
[0093]
If the initial setting in step S1 has been completed, then, after continuously performing the open circuit voltage update process (step S3) and the charge state calculation process (step S5), whether or not the power supply from the battery 13 has been cut off (Step S7), if not cut (N in step S7), return to step S3, if cut (Y in step S7), after performing the end process (step S9) Then, a series of processing is completed.
[0094]
In the open circuit voltage update process of step S3, as shown in the flowchart of the subroutine in FIG. 5, the timer value T in the timer area of the RAM 23b exceeds the predetermined time Th necessary for eliminating the polarization from the maximum polarization occurrence state. (Step S3a), if the predetermined time Th has not been exceeded (N in Step S3a), the open circuit voltage update process is terminated and the process returns to the main routine of FIG. (Y in step S3a), the A / D conversion value of the terminal voltage V of the battery 13 detected by the voltage sensor 17 is acquired from the I / F 21 (step S3b), and the engine room (not shown) detected by the temperature sensor 19 An A / D conversion value of the temperature h is acquired from the I / F 21 (step S3c).
[0095]
Subsequently, the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 and the battery 13 itself or the ambient temperature h at the time when the open circuit voltage OCV is stored and stored. ₁ Is updated to the A / D conversion value of the terminal voltage V of the battery 13 and the temperature h of the engine room acquired in steps S3b and S3c (step S3d), and the flag F in the equilibrium state flag area of the RAM 23b is set to “1”. After the setting (step S3e), the open circuit voltage update process is terminated and the process returns to the main routine of FIG.
[0096]
Further, in the charging state calculation process in step S5, as shown in the flowchart of the subroutine in FIG. 6, it is confirmed whether or not the state of the switches other than the starter switch has shifted from OFF to ON (step S5a). If not (N in Step S5a), the process proceeds to Step S5f to be described later. If the process is shifted (Y in Step S5a), the battery 13 detected by the current sensor 15 obtained as an A / D conversion value from the I / F 21 is detected. It is confirmed whether or not the discharge current I is 0 A (ampere) (step S5b).
[0097]
When the discharge current I of the battery 13 is not 0 A (ampere) (N in step S5b), the time count in the timer area of the RAM 23b is terminated and the timer value T is reset to zero (step S5c), and the flag in the equilibrium state flag area After F is set to “0” (step S5d), the charging state calculation process is terminated and the process returns to the main routine of FIG. 4. When the discharge current I of the battery 13 is 0 A (ampere) (in step S5b) Y) It is confirmed whether or not the starter switch is turned on (step S5e).
[0098]
If the starter switch is not turned on (N in step S5e), the charging state calculation process is terminated and the process returns to the main routine of FIG. 4. If turned on (Y in step S5e), the process proceeds to step S5j described later. move on.
[0099]
On the other hand, if the state of the switches other than the starter switch is not shifted from OFF to ON in step S5a, the process proceeds to (N). In step S5f, it is confirmed whether the state of the switches other than the starter switch has shifted from ON to OFF. If not shifted (N in Step S5f), the process proceeds to Step S5h to be described later. If shifted (Y in Step S5f), time counting in the timer area of the RAM 23b is started (Step S5g). The charging state calculation process is terminated and the process returns to the main routine of FIG.
[0100]
Further, in step S5h, the process proceeds to (N) when the state of the switches other than the starter switch is not shifted from on to off in step S5f. In step S5h, whether or not the starter switch is turned on is checked (step S5h). If not (N in step S5h), the charging state calculation process is terminated and the process returns to the main routine of FIG. 4. If turned on (Y in step S5h), the process proceeds to step S5j.
[0101]
In step S5j that proceeds when the starter switch is turned on in step S5e and step S5h (Y), detection of the current sensor 15 acquired as an A / D conversion value from the I / F 21 as shown in the flowchart of FIG. It is confirmed whether or not the discharge current I of the battery 13 has started to decrease from 250 A (ampere) after reaching 250 A (ampere).
[0102]
If the discharge current I of the battery 13 has not started to decrease from 250A (ampere) after reaching 250A (ampere) (N in step S5j), step S5j is repeated until it reaches 250A (ampere). If the current starts to decrease from 250 A (Ampere) (Y in Step S5j), the A / D conversion value of the discharge current I of the battery 13 detected by the current sensor 15 and the terminal of the battery 13 detected by the voltage sensor 17 The A / D conversion value of the voltage V is acquired as a pair from the I / F 21 (step S5k), and the acquired discharge current I of the battery 13 detected by the current sensor 15 is reduced to 35A (ampere). (Step S5m).
[0103]
If the discharge current I of the battery 13 has not decreased to 35 A (Ampere) (N in Step S5m), the process returns to Step S5k, and if it has decreased (Y in Step S5m), until then in Step S5k Using the A / D conversion values of the terminal voltages V and the discharge currents I of the plurality of sets of batteries 13 obtained in pairs, a correlation coefficient r for confirming the correlation of the data is calculated and It is confirmed whether or not the value is within an allowable range of −0.9 ≧ r ≧ −1.0 (step S5n).
[0104]
If the correlation coefficient r is within the allowable range and the correlation is OK (Y in step S5n), the process proceeds to step S5t described later, and if the correlation coefficient r is not within the allowable range and the correlation is not OK (step After discarding the A / D conversion value pair of the discharge current I of the battery 13 detected by the current sensor 15 and the terminal voltage V of the battery 13 detected by the voltage sensor 17 obtained in step S5k (N in S5n) In step S5p, it is confirmed whether or not the flag F in the equilibrium flag area is “0” (step S5r).
[0105]
If the flag F is “0” (Y in step S5r), the charging state calculation process is terminated and the process returns to the main routine of FIG. 4. If not “0” (N in step S5r), the flag F is set. After setting to “0” (step S5s), the charging state calculation process is terminated and the process returns to the main routine of FIG.
[0106]
Further, in step S5t, the process proceeds to (Y) when the correlation coefficient r is within the allowable range and the correlation is OK in step S5n, and the discharge current I of the battery 13 detected by the current sensor 15 acquired in step S5k. The least square method is applied to a pair of A / D conversion values with the terminal voltage V of the battery 13 detected by the voltage sensor 17 to determine a linear voltage-current characteristic expression V = aI + b, and then a constant current The virtual current value Is = −10 A (ampere) at which the estimated voltage Vn in the discharge shows a linear characteristic with respect to the capacity of the battery 13 is substituted into the voltage-current characteristic equation V = aI + b calculated in step S5t. Thus, the estimated voltage Vn is estimated (step S5v).
[0107]
At the same time, the A / D conversion value of the temperature h of the engine room (not shown) detected by the temperature sensor 19 is used as the temperature h of the battery 13 itself or the surroundings at the estimated time of the estimated voltage Vn. ₂ After acquiring from the I / F 21 (step S5w), it is checked whether or not the flag F in the equilibrium flag area is “0” (step S5x).
[0108]
When the flag F is “0” (Y in step S5x), the process proceeds to step S5B described later, and when it is not “0” (N in step S5x), the open circuit voltage OCV stored and stored in the NVM 25 is used. Subtract the estimated voltage Vn estimated in step S5v to obtain a residual voltage drop value e ₀ (Step S5y) and the remaining voltage drop value e stored and stored in the NVM 27 ₀ Is the residual voltage drop value e obtained in step S5y. ₀ (Step S5z), and the updated residual voltage drop value e of the NVM 27 ₀ In addition, the estimated voltage Vn estimated in step S5v is added to obtain a corrected estimated voltage Vn ′ (step S5A), and then the process proceeds to step S5D described later.
[0109]
In step S5B, which proceeds to (Y) when the flag F in the equilibrium flag area is “0” in step S5x, the battery 13 itself or the surrounding temperature h at the estimated time of the estimated voltage Vn acquired in step S5v. ₂ And the battery 13 itself or the ambient temperature h when the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 is stored and stored in the NVM 25. ₁ Based on the above, the residual voltage drop value e stored and stored in the NVM 27 by the coefficient of the correction data stored in the ROM 23c. ₀ To correct residual voltage drop value e after correction ₀ ′, And then, this corrected residual voltage drop value e ₀ ′ Is added to the estimated voltage Vn acquired in step S5v to obtain a corrected estimated voltage Vn ′ (step S5C), and then the process proceeds to step S5D.
[0110]
In step S5D, which proceeds after obtaining the corrected estimated voltage Vn ′ in step S5A or step S5C, the corrected estimated voltage Vn ′ obtained in step S5A or step S5C is calculated using a voltage ratio calculation formula,
SOC = {(Vn′−Ve) / (Vs−Ve)} × 100 (%)
Or a calculation formula by power ratio,

(Where Vs is the open circuit voltage at full charge, Ve is the open circuit voltage at the end of discharge)
By substituting into any of the equations, the state of charge SOC of the battery 13 is obtained.
[0111]
Subsequently, it is confirmed whether or not the flag F in the equilibrium state flag area is “0” (step S5E). If the flag F is “0” (Y in step S5E), the charge state calculation process is terminated and FIG. 4 is returned to the main routine, and if it is not “0” (N in step S5E), after setting the equilibrium state flag F to “0” (step S5F), the charging state calculation process is terminated and the main routine of FIG. Return to routine.
[0112]
As is clear from the above description, in the battery capacity calculation device 1 of the present embodiment, step S5t in the flowchart of FIG. 7 is processing corresponding to the characteristic indexing means 23A in the claims. Step S5v is a process corresponding to the estimated voltage estimation means 23B in the claims, and step S5j in FIG. 7 is a process corresponding to the residual voltage drop value indexing means 23D in the claims. It has become.
[0113]
Further, in the battery capacity calculation device 1 of the present embodiment, step S3a in the flowchart of FIG. 5 is processing corresponding to the equilibrium state determination means 23C in the claims, and step S3d in FIG. The process corresponds to the open circuit voltage update means 23E in the middle, and step S5B in FIG. 7 is the process corresponding to the correction means 23F in the claims.
[0114]
Furthermore, in the battery capacity calculation device 1 of the present embodiment, the current sensor 15 and step S5j in FIG. 7 constitute the discharge current decrease start detecting means A in the claims, and the current sensor 15 and FIG. The step S5m in FIG. 7 constitutes the discharge current drop detecting means C in the claims, and the voltage sensor 17 and the step S3b in FIG. Is configured.
[0115]
Further, in the battery capacity calculation device 1 of the present embodiment, regarding the discharge current I of the battery 13, 250 A (ampere) corresponds to the predetermined large current value in the claims, and 35 A (ampere) in the claims. This corresponds to the target current value.
[0116]
Next, the operation (action) of the battery capacity calculation device 1 of the present embodiment configured as described above will be described.
[0117]
First, an electrical component (load) other than the motor generator 5 of the hybrid vehicle is operated, the motor generator 5 is operating so as to function as a motor, and the battery 13 is discharged accordingly, or When the motor generator 5 operates to function as a generator and the battery 13 is charging accordingly, the open circuit voltage OCV stored and stored in the NVM 25 and the open circuit voltage OCV are stored in the NVM 25. Battery 13 itself or ambient temperature h when stored and stored ₁ And the remaining voltage drop value e stored and stored in the NVM 27 ₀ No update is performed, and the estimated voltage Vn is not estimated, and the state of charge SOC using the estimated voltage Vn is not calculated or updated.
[0118]
Next, when the starter switch is turned on, the motor generator 5 of the hybrid vehicle is operated so as to function as a cell motor, and the battery 13 performs constant load discharge with a predetermined large current value exceeding 250 A (ampere). And the discharge current I of the battery 13 and the terminal voltage V detected by the current sensor 15 and the voltage sensor 17 until the discharge current I of the battery 13 in the discharge decreases to a target current value of 35 A (ampere). When pairs are periodically collected and satisfy a certain correlation, the least square method is applied to them, and the linear voltage-current characteristic equation V = aI + b of the battery 13 is divided. The virtual current value Is = −1 that is output and the estimated voltage Vn in the constant current discharge exhibits a linear characteristic with respect to the capacity of the battery 13 A (amperes), the voltage - by substituting the current characteristic equation V = aI + b, the estimated voltage Vn is estimated.
[0119]
The battery 13 itself or the surrounding temperature h at the estimated time of the estimated voltage Vn ₂ And the battery 13 itself or the ambient temperature h when the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 is stored and stored in the NVM 25. ₁ And the residual voltage drop value e stored and stored in the NVM 27 according to the difference. ₀ Is corrected for temperature compensation, and the corrected residual voltage drop value e is corrected. ₀ 'Is added to the previously estimated voltage Vn to obtain the corrected estimated voltage Vn', and this corrected estimated voltage Vn 'is substituted into either the voltage ratio or power ratio calculation formula. Thus, the state of charge SOC of the battery 13 is calculated, and the result is provided as display and capacity management data.
[0120]
In this case, in order to obtain the voltage-current characteristic equation V = aI + b of the battery 13 used to estimate the estimated voltage Vn, the discharge current I and the terminal voltage V of the battery 13 collected periodically as a pair are , 250 A (ampere), collected at the time of discharging to the motor generator 5 that functions as a cell motor that is the maximum load in the hybrid vehicle, and the power of the battery 13 is supplied to other loads simultaneously. However, it was collected in a state where a discharge current I exceeding 35 A (ampere) which does not reach even though it flows.
[0121]
For this reason, even if the power of the battery 13 is supplied to a load other than the motor generator 5 at the same time and a voltage drop due to the discharge side polarization is caused thereby, the remaining due to the influence of the residual polarization at the end of the discharge to the motor generator 5 Residual voltage drop value e obtained as voltage drop amount ₀ Is added to the estimated voltage Vn thus estimated, the actual state of charge SOC of the battery 13 can be accurately calculated.
[0122]
Further, in the battery capacity calculation device 1 of the present embodiment, when the battery 13 performs a constant load discharge exceeding 250 A (ampere) with the starter switch being turned on, the maximum polarization occurrence state is in a stage before the start of the discharge. If the battery 13 has not been charged / discharged for a predetermined time Th required for eliminating polarization from the battery, voltage fluctuation (voltage rise or voltage drop) due to polarization that occurred when the battery 13 was previously charged / discharged Is completely eliminated and the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 is updated to the terminal voltage V of the battery 13 detected at this time.
[0123]
For this reason, even if the open circuit voltage OCV fluctuates due to the change in capacity of the battery 13, the open circuit voltage OCV stored and stored in the NVM 25 is updated to the latest value every time the battery 13 is in an equilibrium state. The calculation accuracy of the thirteen state of charge SOC can be maintained high.
[0124]
Similarly, in the battery capacity calculation device 1 of the present embodiment, when the battery 13 is discharged from the motor generator 5 that functions as a cell motor from a state in which the battery 13 is in an equilibrium state, the battery stored and stored in the NVM 27 is stored. 13 residual voltage drop value e ₀ Is the latest remaining voltage drop value e obtained by subtracting the estimated voltage Vn estimated after the discharge from the open circuit voltage OCV of the NVM 25 updated before the start of the discharge. ₀ Updated to
[0125]
For this reason, the remaining voltage drop value e as the state of the battery 13 changes. ₀ The remaining voltage drop value e stored and stored in the NVM 27 every time the battery 13 is in an equilibrium state ₀ Can be updated to the latest value, and the calculation accuracy of the state of charge SOC of the battery 13 can be maintained high.
[0126]
Further, in the battery capacity calculation device 1 of the present embodiment, the battery 13 itself or the ambient temperature h at the time when the open circuit voltage OCV is stored and stored in the NVM 25. ₁ And the temperature h of the battery 13 itself or the surroundings at the estimated time of the estimated voltage Vn ₂ Is different from the residual voltage drop value e in accordance with the difference. ₀ Is used to calculate the state of charge SOC of the battery 13 by adding it to the estimated voltage Vn. ₀ Therefore, the residual voltage drop value e ₀ And the residual voltage drop value e ₀ Is added to the estimated voltage Vn to calculate the state of charge SOC of the battery 13, even if there is a change in the battery 13 itself or the surrounding temperature h that changes the value of the open circuit voltage OCV. The charge state SOC of the battery 13 can be calculated with high accuracy.
[0127]
Incidentally, the above-described residual voltage drop value e employed in the present embodiment. ₀ For temperature compensation, open circuit voltage OCV and / or residual voltage drop value e ₀ A part or all of the configuration for updating may be omitted as long as there is no problem in relation to the required accuracy.
[0128]
In addition, in order to obtain the voltage-current characteristic equation V = aI + b of the battery 13 used for estimating the estimated voltage Vn, the period in which the discharge current I and the terminal voltage V of the battery 13 are periodically collected is When the battery 13 performs a constant load discharge exceeding 250 A (ampere) as in the battery capacity calculation device 1 of the embodiment, not only while the discharge current I decreases from 250 A (ampere) to 35 A (ampere). May be.
[0129]
However, generally, the voltage-current characteristics during discharge of the battery 13 are different between when the discharge current I increases and when the discharge current I increases, and the battery 13 actually has a constant load exceeding 250 A (ampere). When the discharge current I and the terminal voltage V are measured when the discharge is performed, the voltage drop due to the polarization generated in the battery 13 due to the discharge decreases with the decrease of the discharge current I as shown in the graph of FIG. Since the pace of elimination is delayed with respect to the pace of occurrence accompanying the increase in the discharge current I, the terminal voltage V becomes lower with respect to the discharge current I when the discharge current I is decreasing than when the discharge current I is increasing.
[0130]
Moreover, when the discharge of the battery 13 is started in a state where the voltage increase or voltage drop due to the previous charge / discharge remains, the voltage − during the increase of the discharge current I as shown in the graph of FIG. The current characteristic is different from the voltage-current characteristic during the increase of the discharge current I when the discharge is started from the equilibrium state described above with reference to the graph of FIG.
[0131]
Therefore, the voltage-current characteristics of the battery 13 are not the same when the discharge current I is increasing and decreasing, and the voltage-current characteristics when the discharge current I is increasing are the same as those of the battery 13 before the start of discharge. Is considered to be different depending on whether or not the battery is in an equilibrium state, at least the battery capacity calculation device 1 of the present embodiment is not used unless a situation in which the characteristic difference has an influence of a slight error is ensured. Thus, it is preferable to obtain the voltage-current characteristic formula V = aI + b of the battery 13 using only the discharge current I and the terminal voltage V of the battery 13 collected periodically only while the discharge current I is decreasing. It can be said that it is preferable.
[0132]
In the battery capacity calculation device 1 of the present embodiment, the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 is the discharge current of the voltage-current characteristic line during the increase of the discharge current I in FIG. It represents a point on I = 0 A (ampere), and is obtained using only the discharge current I and the terminal voltage V of the battery 13 collected while the discharge current I is reduced from 250 A (ampere) to 35 A (ampere). The voltage-current characteristics of the battery 13 are Expression 8 indicates a point on the virtual current value Is = −10 A (ampere) of the voltage-current characteristic line during the decrease of the discharge current I in FIG. 8.
[0133]
In this embodiment, the voltage-current characteristic of the battery 13 at the time of constant load discharge is approximated to the primary voltage-current characteristic equation V = aI + b, but the influence of the nonlinear characteristic of the polarization resistance component As shown in FIG. 11, instead of the primary voltage-current characteristic equation V = aI + b, the least square method is used to obtain the discharge current I and the terminal voltage V of the battery 13 during constant load discharge. V = aI ² You may make it approximate to the quadratic curve formula of + bI + c.
[0134]
In such a case, this approximate curve formula V = aI ² The estimated voltage Vn is estimated by substituting the virtual current value Is = −10 A (ampere) into + bI + c, and the latest remaining voltage drop value e is estimated using the estimated voltage Vn. ₀ To update or set the estimated voltage Vn to the estimated voltage drop value e. ₀ Is added to calculate the open circuit voltage OCV of the battery 13.
[0135]
Thus, if the voltage-current characteristic of the battery 13 is a quadratic approximate curve equation, the discharge current I with respect to the pace of increase / decrease in the voltage drop amount of the terminal voltage V generated in the battery 13 due to polarization due to discharge. The slowness in the pace of increase / decrease is reflected more accurately than the first-order voltage-current characteristic equation V = aI + b, and this approximate curve equation V = aI ² This is advantageous because the accuracy of the estimated voltage Vn estimated using + bI + c and the accuracy of the open circuit voltage OCV calculated using the estimated voltage Vn can be further increased.
[0136]
Further, in the present embodiment, polarization is performed using the discharge current I and the terminal voltage V of the battery 13 at the time of constant load discharge exceeding 250 A (ampere) when the motor generator 5 that consumes the most power alone is operated. The voltage-current characteristic equation V = aI + b including the influence of the above is calculated, but at least if the current value is sufficient to eliminate the charge side polarization occurring in the battery 13 immediately before discharging, the discharge current Using the discharge current I and the terminal voltage V of the battery 13 that accompanies the operation of the load other than the motor generator 5 so that the maximum value is not far from 250 A (ampere), the voltage-current characteristic formula V including the influence of polarization is used. = AI + b or the two approximate curve equations M1 and M2 having the above-described VI characteristic may be calculated.
[0137]
【The invention's effect】
As described above, according to the battery capacity calculation method of the present invention described in claim 1, the terminal voltage and the discharge current of the battery that supplies power to the load of the vehicle are periodically measured, and these terminal voltages are calculated. Voltage-current characteristics showing correlation with discharge current Represents the expression The voltage-current characteristics Represents the expression Estimating an estimated voltage that is an estimated terminal voltage in a constant load discharge state of the battery, and using the estimated voltage to calculate the charge capacity of the battery,
Based on an expression representing the voltage-current characteristics of the battery in various charge capacities, a current value giving a voltage that linearly changes in response to the change in the charge capacity is obtained in advance as a virtual current value, The voltage-current characteristic while the discharge current of the constant load discharge by the battery in the equilibrium state is decreasing from a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge. Substituting the virtual current value into the expression The estimated value of the estimated voltage of the battery at the time of constant load discharge with the predetermined large current value, and the state of the battery in the equilibrium state before the start of the constant load discharge used to estimate the value of the estimated voltage A difference value from the value of the open circuit voltage, which is a terminal voltage, is obtained in advance as a residual voltage drop value that is a residual voltage drop amount due to the influence of residual polarization at the end of discharge of the battery. The battery terminal voltage and discharge current measured periodically during the constant load discharge every time constant load discharge is performed with a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge. And the voltage-current characteristics Represents the expression The voltage-current characteristics Substituting the virtual current value into the expression The current estimated voltage of the battery is estimated, and the current charge capacity of the battery is calculated by adding the remaining voltage drop value to the estimated current estimated voltage value of the battery.
[0138]
Therefore, the battery terminal voltage measured periodically during the constant load discharge together with the discharge current includes a voltage drop due to the discharge, and the voltage-current characteristic of the battery obtained using this terminal voltage is obtained. Expression And this voltage-current characteristic Expression Even if the current estimated voltage of the battery estimated from the above reflects the voltage drop due to discharge, it corresponds to the maximum power supply value to the vehicle load equivalent to the voltage drop component reflected in the estimated voltage Estimated by adding the residual voltage drop value, which is the amount of residual voltage drop due to the effect of residual polarization at the end of the constant load discharge performed by the battery at a predetermined large current value, to the current estimated voltage value of the battery The voltage drop component reflected in the voltage is canceled by the remaining voltage drop value, and the state of charge of the battery can be accurately calculated.
[0139]
According to the battery capacity calculation method of the present invention described in claim 2, in the battery capacity calculation method of the present invention described in claim 1, the value of the terminal voltage of the battery in the equilibrium state is measured in advance, The measured value is set to the value of the open circuit voltage, and following the setting of the open circuit voltage, the battery in the equilibrium state cancels the charge side polarization that has occurred in the battery at least immediately before the discharge. When a constant load discharge with a sufficient current value is performed, a voltage-current is obtained from the battery terminal voltage and the discharge current measured periodically while the discharge current of the constant load discharge decreases from the maximum current value. Characteristics Represents the expression The voltage-current characteristics Substituting the virtual current value into the expression Estimating the estimated voltage of the battery during constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery at least immediately before the discharge from the equilibrium state, and the estimated equilibrium state The estimated voltage value of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge is calculated from the set open circuit voltage. The residual voltage drop value is obtained in advance by subtracting from the value.
[0140]
Therefore, in the battery capacity calculation method according to the first aspect of the present invention, the constant-load discharge is performed with a current value sufficient for the battery in an equilibrium state to eliminate the charge-side polarization that has occurred in the battery immediately before the discharge. Since the value of the open circuit voltage is acquired and set, and the residual voltage drop value is acquired by subtracting the estimated voltage estimated later from the acquired open circuit voltage, It is possible to eliminate the need to recognize the open circuit voltage and the residual voltage drop value and set them by themselves.
[0141]
Furthermore, according to the battery capacity calculation method of the present invention described in claim 3, in the battery capacity calculation method of the present invention described in claim 2, the value of the open circuit voltage every time the battery is in an equilibrium state. Is updated to the value of the terminal voltage of the battery measured in the equilibrium state.
[0142]
For this reason, in the battery capacity calculation method of the present invention described in claim 2, the open circuit voltage value is updated to the latest one every time the battery is in an equilibrium state, and the remaining voltage drop value is also set to the open circuit. Each time the voltage value is updated to the latest value, the latest value can be obtained in advance, and the battery voltage calculated by adding the remaining voltage drop value to the current estimated voltage of the battery is calculated. The state of charge can always be accurately calculated in response to fluctuations in the open circuit voltage due to changes in the state of charge of the battery.
[0143]
According to the battery capacity calculation method of the present invention described in claim 4, in the battery capacity calculation method of the present invention described in claim 1, 2, or 3, the battery is generated in the battery at least immediately before discharging. Every time constant load discharge is performed with a current value sufficient to cancel the charge side polarization, the battery of the battery was periodically measured while the discharge current during the constant load discharge decreased from the maximum current value. From the terminal voltage and discharge current, the voltage-current characteristics are Represents the expression The voltage-current characteristics Substituting the virtual current value into the expression The current estimated voltage of the battery is estimated.
[0144]
For this reason, in the battery capacity calculation method according to the first, second, or third aspect of the present invention, an increase or decrease in voltage drop due to discharge-side polarization is delayed with respect to an increase or decrease in discharge current in constant load discharge. Therefore, the voltage-current characteristics of the battery are different between the increase and decrease of the discharge current, and the battery terminal voltage rise and voltage drop due to the polarization generated by the previous charge and discharge remain, Even if the battery is subjected to constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery just before the discharge, the voltage that always appears as the same characteristics without being affected by it- The current estimated voltage of the battery is estimated using the current characteristic part, and the battery charge state is calculated by the voltage change due to the polarization generated by the previous charge / discharge. It can be performed with high accuracy without being of influence.
[0145]
Further, according to the battery capacity calculation method of the present invention described in claim 5, in the battery capacity calculation method of the present invention described in claim 1, 2, 3 or 4, the battery capacity calculation method of the present invention described above is generated in the battery at least immediately before discharging. The current value sufficient to eliminate the charge-side polarization is set to a predetermined large current value required when starting the cell motor of the vehicle, and the discharge current value of the battery starts to decrease from the predetermined large current value. , Periodically measured until the current value drops to a target current value that is lower than the predetermined large current value and is equal to or greater than the maximum discharge current value when the vehicle load other than the cell motor is being driven. The voltage-current characteristics used to estimate the estimated voltage of the battery during constant load discharge with the predetermined large current value from the terminal voltage and discharge current of the battery Represents the expression I asked for it.
[0146]
For this reason, in the battery capacity calculation method of the present invention described in claim 1, discharge is performed with a predetermined large current value even if the load of the vehicle other than the cell motor is still driven. Only the remaining components of the voltage drop due to the discharge-side polarization, which is eliminated by the reduction of the discharge current to the target current value, are purely reflected from the battery terminal voltage and the discharge current. It is possible to obtain a voltage-current characteristic and an estimated voltage that exclude the influence of power supply on the vehicle load, and to accurately calculate the state of charge of the battery.
[0147]
According to the battery capacity calculation method of the present invention described in claim 6, in the battery capacity calculation method of the present invention described in claim 1, 2, 3, 4 or 5, the battery capacity is calculated at least immediately before discharging. Every time the estimated voltage of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge-side polarization that has been performed, the ambient temperature of the battery and the open circuit voltage at the estimated time were obtained. Check if there is a difference from the ambient temperature of the battery at the time, and if there is a difference, correct the remaining voltage drop value according to the temperature difference, and use the corrected remaining voltage drop value to The current charging capacity of was calculated.
[0148]
Therefore, in the battery capacity calculation method according to the first, second, third, fourth, or fifth aspect of the present invention, the battery ambient temperature changes to change the battery capacity, and the battery open circuit is changed according to the capacity. Even if the voltage changes with respect to the open circuit voltage used to obtain the remaining voltage drop value in advance, temperature compensation is performed by correcting the remaining voltage drop value, so that the current battery Can be calculated with high accuracy.
[0149]
Furthermore, according to the battery capacity calculation device of the present invention as set forth in claim 7, the battery for supplying power to the load of the vehicle is sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge. During constant load discharge at a constant current value, the terminal voltage and discharge current of the battery during this constant load discharge are measured periodically to obtain a voltage-current characteristic indicating the correlation between these terminal voltage and discharge current. Represents the expression The voltage-current characteristics Represents the expression An estimated voltage, which is an estimated terminal voltage in a constant load discharge state of the battery, is used to calculate a charge capacity of the battery using the estimated voltage; The voltage-current characteristic while the discharge current of the load discharge is decreasing from a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge. Expression In A current that gives an estimated voltage, which is a voltage that changes linearly in response to the change in the charge capacity, obtained in advance based on an expression representing the voltage-current characteristics of the battery 13 in various charge capacities, is a virtual current. Substituting as a value Used to estimate the estimated voltage value of the battery and the estimated voltage value at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization occurring in the battery at least immediately before the discharge The difference between the value of the open circuit voltage that is the terminal voltage of the battery in an equilibrium state before the start of the constant load discharge is the residual voltage drop that is the residual voltage drop due to the influence of the residual polarization at the end of the battery discharge. A residual voltage drop value storage means for storing the value as a value, and adding the residual voltage drop value stored in the residual voltage drop value storage means to the estimated voltage value of the battery, The current charging capacity of the battery is calculated.
[0150]
Therefore, the battery terminal voltage measured periodically during the constant load discharge together with the discharge current includes a voltage drop due to the discharge, and the voltage-current characteristic of the battery obtained using this terminal voltage is obtained. Expression And this voltage-current characteristic Expression Even if the current estimated voltage of the battery estimated from the above reflects the voltage drop due to the discharge, it is equivalent to the voltage drop component reflected in the estimated voltage, at least the charge that occurred in the battery immediately before the discharge The residual voltage drop value stored in the residual voltage drop value storage means, which is the residual voltage drop amount due to the influence of the residual polarization at the end of the constant load discharge performed by the battery with a current value sufficient to eliminate the side polarization, By adding to the current estimated voltage value of the battery, the voltage drop component reflected in the estimated voltage is offset by the remaining voltage drop value, and the battery charge state is accurately calculated
Can do.
[0151]
According to the battery capacity calculation apparatus of the present invention described in claim 8, in the battery capacity calculation apparatus of the present invention described in claim 7, at least the charge side polarization generated in the battery immediately before discharging is eliminated. Discharge current decrease start detecting means for detecting that the discharge current of the battery starts to decrease from the maximum current value in the constant load discharge of the battery at a current value sufficient to perform, and the discharge current of the battery is the maximum current After the discharge current decrease start detecting means detects that the current starts to decrease from the value, the voltage-current characteristic is obtained from the terminal voltage and discharge current of the battery measured periodically. Represents the expression The characteristic indexing means to be obtained and the voltage-current characteristic obtained by the characteristic indexing means Substituting the virtual current value into the expression An estimated voltage estimating means for estimating an estimated voltage of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before discharging, A configuration for calculating a current charge capacity of the battery by adding the remaining voltage drop value stored in the remaining voltage drop value storage means to the estimated voltage value of the battery estimated by the estimated voltage estimation means; did.
[0152]
For this reason, in the battery capacity calculation device of the present invention described in claim 7, since the increase or decrease of the voltage drop due to the discharge side polarization is delayed with respect to the increase or decrease of the discharge current in the constant load discharge, The battery's voltage-current characteristics are different between increasing and decreasing current, and the battery terminal voltage rise or drop due to the polarization caused by the previous charge / discharge remains, and the specified large current Even when the battery is subjected to constant load discharge by value, the voltage-current characteristics that always appear as the same characteristics without being affected by them Represents the expression The voltage-current characteristic obtained by the characteristic indexing means Obtained by substituting the virtual current value into the expression Using the current estimated voltage of the battery estimated by the estimated voltage estimation means, the battery charge state is calculated, and the battery charge state calculation is performed to account for the effects of voltage fluctuations due to polarization generated by the previous charge / discharge. It can be performed accurately without receiving.
[0153]
Furthermore, according to the battery capacity calculation device of the present invention described in claim 9, in the battery capacity calculation device of the present invention described in claim 8, an open circuit voltage value storage means for storing the value of the open circuit voltage; The battery is generated in the battery at least immediately before the discharge from the battery that is determined to be in the equilibrium state by the equilibrium state determination means and the battery that is determined to be in the equilibrium state by the equilibrium state determination means. The open circuit voltage stored in the open circuit voltage value storage means is the estimated voltage value of the battery estimated by the estimated voltage estimation means during a constant load discharge with a current value sufficient to eliminate charge side polarization. A residual voltage drop value calculating means for subtracting the remaining voltage drop value from the value of the remaining voltage drop value, wherein the residual voltage drop value storing means is obtained by the residual voltage drop value calculating means. It was was configured for storing the residual voltage drop value.
[0154]
For this reason, in the battery capacity calculation device according to the present invention as set forth in claim 8, the battery determined to be in the equilibrium state by the equilibrium state determination means eliminates the charge side polarization generated in the battery immediately before discharging. The residual voltage drop value stored in the residual voltage drop value storage means is calculated by using the estimated voltage value estimated by the estimated voltage estimation means when the constant load discharge is performed with a current value sufficient for the residual voltage drop value assignment. As required by the output means, it is possible to eliminate the need to recognize the residual voltage drop value in advance and set it.
[0155]
According to the battery capacity calculation device of the present invention as set forth in claim 10, in the battery capacity calculation device of the present invention as set forth in claim 9, in the state determined by the equilibrium state determination means as being in an equilibrium state. The balanced terminal voltage measuring means for measuring the terminal voltage of the battery, and the terminal voltage of the battery measured by the balanced terminal voltage measuring means for the value of the open circuit voltage stored in the open circuit voltage value storage means. And an open circuit voltage updating means for updating to the above value.
[0156]
For this reason, in the battery capacity calculation device according to the ninth aspect of the present invention, the open circuit voltage stored in the open circuit voltage value storage means is determined each time the battery is determined to be in an equilibrium state by the equilibrium state determination means. The value of the open circuit voltage stored in the open circuit voltage value storage means is set such that the value is updated by the open circuit voltage update means to the value of the battery terminal voltage measured by the equilibrium terminal voltage measurement means. The battery charge state calculated by always updating to the latest voltage and adding the remaining voltage drop value to the current estimated voltage of the battery corresponds to fluctuations in the open circuit voltage due to changes in the battery charge state, etc. It can always be calculated accurately.
[0157]
Furthermore, according to the battery capacity calculation device of the present invention described in claim 11, in the battery capacity calculation device of the present invention described in claim 10, temperature detection means for detecting the ambient temperature of the battery, When the estimated voltage is estimated by the estimated voltage estimating means, the ambient temperature of the battery detected by the temperature detecting means and when the balanced terminal voltage measuring means measures the terminal voltage of the battery, the temperature detection If there is a difference, the residual voltage drop value stored in the residual voltage drop value storage means is corrected according to the temperature difference. And when the residual voltage drop value is corrected by the correcting means, the corrected residual voltage drop value is used as the estimated voltage. By adding to the value of the estimated voltage of the battery constant means it is estimated, and a configuration for calculating a present charging capacity of the battery.
[0158]
For this reason, in the battery capacity calculation device of the present invention described in claim 10, the battery ambient temperature detected by the temperature detecting means changes to change the battery capacity, and the open circuit voltage of the battery varies according to the capacity. The residual voltage drop value is corrected by the correction means even if the open circuit voltage stored in the open circuit voltage value storage means is used when the residual voltage drop value is calculated by the residual voltage drop value calculating means. Thus, temperature compensation can be performed, and the current charge capacity of the battery according to the current battery ambient temperature can be accurately calculated.
[0159]
According to the battery capacity calculation device of the present invention described in claim 12, the battery capacity calculation device of the present invention described in claim 8, 9, 10 or 11 is generated in the battery at least immediately before discharging. The current value sufficient to eliminate the charging-side polarization is a predetermined large current value required when starting the cell motor of the vehicle, and the discharge current decrease start detecting means It is configured to detect that the discharge current of the battery starts to decrease from the predetermined large current value, and the discharge current decrease start detecting means detects that the battery starts to decrease from the predetermined large current value. A discharge current that detects that the discharge current of the battery has decreased to a target current value that is equal to or greater than the maximum discharge current value when the vehicle load other than the cell motor is being driven. Further comprising a decrease detection means, wherein the characteristic index means detects the target current after the discharge current decrease start detection means detects that the discharge current of the battery has started to decrease from the predetermined large current value. Until the discharge current drop detecting means detects that the voltage has dropped to a value, the voltage-current characteristic is calculated from the terminal voltage and discharge current of the battery measured periodically. Represents the expression The required configuration was adopted.
[0160]
For this reason, in the battery capacity calculation device according to the present invention as set forth in claim 8, 9, 10 or 11, even if the load of the vehicle other than the cell motor is still driven, the discharge was performed with a predetermined large current value. The discharge current decreases to the target current value after the discharge current decrease start detecting means detects that the battery discharge current has started to decrease from a predetermined large current value. Until the discharge current drop detection means detects that, the remaining components excluding the voltage drop that has been eliminated by the drop in the discharge current are purely reflected from the battery terminal voltage and discharge current, except for the cell motor. Voltage-current characteristics that eliminate the influence of power supply on the vehicle load Expression And the estimated voltage can be obtained by the characteristic indexing means and the estimated voltage estimating means, and the state of charge of the battery can be accurately calculated.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a battery capacity calculation device of the present invention.
FIG. 2 is an explanatory diagram partially showing a schematic configuration of a battery capacity calculation apparatus according to an embodiment of the present invention to which the battery capacity calculation method of the present invention is applied.
3 is a graph showing an example of correction data for a residual voltage drop value stored in a ROM of the microcomputer of FIG. 2;
4 is a flowchart showing a main routine of processing performed by a CPU in accordance with a control program stored in a ROM of the microcomputer of FIG. 2. FIG.
5 is a flowchart of a subroutine showing an open circuit voltage update process of FIG. 4. FIG.
6 is a flowchart of a subroutine showing charge state calculation processing of FIG. 4;
7 is a flowchart of a subroutine showing charge state calculation processing of FIG. 4;
FIG. 8 is a graph showing a general voltage-current characteristic difference between an increase and a decrease in discharge current in constant load discharge performed by a battery in an equilibrium state.
9 is a graph showing a voltage-current characteristic difference between when the discharge current is increased and when the discharge current is increased in a 250 A constant load discharge performed from the equilibrium state of the battery of FIG. 2;
FIG. 10 is a graph showing a general voltage-current characteristic difference between an increase and a decrease in discharge current in a constant load discharge performed by a battery that is not in an equilibrium state.
FIG. 11 shows an example of a voltage-current characteristic of a battery expressed by a quadratic approximation obtained by applying the least square method to a set of a predetermined number of terminal voltages and discharge currents sampled during constant current discharge of the battery. It is a graph to show.
FIG. 12 is a graph showing a correlation between terminal voltage and discharge time in constant current discharge of a battery.
FIG. 13 is a schematic diagram showing a relationship between a set of a predetermined number of terminal voltages and discharge currents sampled during constant current discharge of a battery and a linear voltage-current characteristic equation obtained by applying the least square method thereto. It is a graph shown in.
14 is a graph showing a plurality of constant current discharge characteristics obtained from an estimated voltage estimated from the voltage-current characteristics shown in FIG.
15 is a graph showing a plurality of hypothetical constant current discharge characteristics obtained from an estimated voltage estimated from the voltage-current characteristics shown in FIG.
FIG. 16 is a graph in which voltage-current characteristics of a battery corresponding to each capacity are developed on the same plane.
17 is a graph showing the relationship between the capacity of the battery at the virtual discharge current value showing the linear characteristic in the graph of FIG. 15 and the estimated voltage estimated from the voltage-current characteristic shown in FIG.
FIG. 18 is a graph showing the content of a voltage drop that occurs during battery discharge.
[Explanation of symbols]
5 Cell motor
13 battery
19 Temperature detection means
23 Microcomputer
23a CPU
23b RAM
23c ROM
23A Characteristic indexing means
23B Estimated voltage estimation means
23C Equilibrium state determination means
23D Residual voltage drop value indexing means
23E open circuit voltage update means
23F Correction means
25 Open circuit voltage value storage means
27 Residual voltage drop value storage means
A Discharge current decrease start detection means
B Balanced terminal voltage measurement means
C Discharge current drop detection means

Claims (12)

A terminal voltage and a discharge current of a battery that supplies power to a vehicle load are periodically measured to obtain a voltage-current characteristic indicating a correlation between the terminal voltage and the discharge current, and the voltage-current characteristic is used to determine the voltage-current characteristic. In estimating the estimated voltage which is the terminal voltage on the assumption in the constant load discharge state of the battery, in calculating the charge capacity of the battery using this estimated voltage,
Based on an expression representing the voltage-current characteristics of the battery in various charge capacities, a current value giving a voltage that linearly changes in response to the change in the charge capacity is obtained in advance as a virtual current value,
A voltage-current characteristic is obtained while the discharge current of the constant load discharge by the battery in the equilibrium state is decreased from a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge. In the expression
The current that gives the estimated voltage, which is a voltage that changes linearly in response to the change in the charge capacity, obtained in advance based on the expression representing the voltage-current characteristics of the battery at various charge capacities, is used as the virtual current value. Substituted and estimated value of the estimated voltage of the battery at the time of constant load discharge with the predetermined large current value, and the equilibrium state before the start of the constant load discharge used to estimate the value of the estimated voltage A difference value from the value of the open circuit voltage that is the terminal voltage of the battery is determined in advance as a residual voltage drop value that is a residual voltage drop amount due to the effect of residual polarization at the end of discharge of the battery,
Thereafter, each time the battery performs constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery at least immediately before the discharge, the battery was periodically measured during the constant load discharge. An expression representing voltage-current characteristics is obtained from the terminal voltage and discharge current of the battery, and the current estimated voltage of the battery is estimated by substituting the virtual current value into the expression representing the voltage-current characteristics .
A battery capacity calculation method, wherein the current charge capacity of the battery is calculated by adding the remaining voltage drop value to the estimated current voltage value of the battery. Preliminarily measure the terminal voltage value of the battery in an equilibrium state and set the measured value to the open circuit voltage value;
Following the setting of the open circuit voltage, when the battery in an equilibrium state performs a constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge, the discharge current of the constant load discharge was periodically measured during the decrease from the maximum current value, the terminal voltage of the battery and the discharge current, voltage - determine the equation representative of the current characteristics,
By substituting the virtual current value into this voltage-current characteristic expression, constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge from the equilibrium state Estimate the estimated voltage of the battery at the time,
The battery capacity calculation method according to claim 1, wherein the remaining voltage drop value is obtained in advance by subtracting the estimated value of the estimated voltage of the battery from the set value of the open circuit voltage.   3. The battery capacity calculation method according to claim 2, wherein each time the battery is in an equilibrium state, the value of the open circuit voltage is updated and set to the value of the terminal voltage of the battery measured in the equilibrium state. The discharge current of the constant load discharge decreases from the maximum current value every time the battery performs a constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge. An expression representing a voltage-current characteristic is obtained from the terminal voltage and discharge current of the battery measured periodically, and the current estimated voltage of the battery is estimated using the expression representing the voltage-current characteristic. battery capacity calculation method according to one wherein either claims 1, 2 or 3 and to perform. At least a current value sufficient to eliminate the charge-side polarization occurring in the battery immediately before discharging is a predetermined large current value required when starting the cell motor of the vehicle, and the discharging current value of the battery is After starting to decrease from a predetermined large current value, the target current value decreases to a target current value that is lower than the predetermined large current value and equal to or greater than the maximum discharge current value when the vehicle load other than the cell motor is being driven. Voltage-current characteristics used to estimate the estimated voltage of the battery during constant load discharge with the predetermined large current value from the terminal voltage and discharge current of the battery measured periodically. The battery capacity calculation method according to any one of claims 1, 2, 3, and 4, wherein an expression to be expressed is obtained. Every time the estimated voltage of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery at least immediately before the discharge is estimated, the ambient temperature of the battery at the estimated time point Confirming whether there is a difference from the ambient temperature of the battery at the time of obtaining the open circuit voltage, and if there is a difference, correct the residual voltage drop value according to the temperature difference, and correct the residual battery capacity calculation method according to claim 1, 2, 3, 4 or 5 Izure or claim which is adapted for calculating a present charging capacity of the battery by using the voltage drop value. The terminal voltage of the battery at the time of constant load discharge of the battery that supplies power to the vehicle load at the time of constant load discharge at a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge And a discharge current are periodically measured to obtain an expression representing a voltage-current characteristic indicating a correlation between the terminal voltage and the discharge current, and the constant load discharge state of the battery is calculated using the expression representing the voltage-current characteristic. In a battery capacity calculation device that estimates an estimated voltage that is an estimated terminal voltage in and calculates the charge capacity of the battery using the estimated voltage,
The voltage-current characteristic while the discharge current of the constant load discharge by the battery in the equilibrium state is decreasing from a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge. In the expression
The current that gives the estimated voltage, which is a voltage that changes linearly in response to the change in the charge capacity, obtained in advance based on the expression representing the voltage-current characteristics of the battery at various charge capacities, is used as the virtual current value. Substituting and estimating the estimated voltage value of the battery at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization that occurred in the battery immediately before discharging, and the estimated voltage value The difference value from the value of the open circuit voltage that is the terminal voltage of the battery in the equilibrium state before the start of the constant load discharge used to estimate the residual voltage due to the influence of the residual polarization at the end of the discharge of the battery A residual voltage drop value storage means for storing the residual voltage drop value as a drop amount;
The current charge capacity of the battery is calculated by adding the remaining voltage drop value stored in the remaining voltage drop value storage means to the estimated value of the estimated voltage of the battery. Battery capacity calculation device. Detects that the discharge current of the battery starts to decrease from the maximum current value in the constant load discharge of the battery at a current value sufficient to eliminate the charge-side polarization occurring in the battery at least immediately before the discharge. Discharge current decrease start detecting means;
After the discharge current decrease start detecting means detects that the discharge current of the battery starts to decrease from the maximum current value, a voltage-current characteristic is expressed from the terminal voltage and discharge current of the battery measured periodically. A characteristic indexing means for obtaining an expression ;
Using the formula representing the voltage-current characteristics obtained by the characteristic indexing means, the constant load discharge at the time of constant load discharge with a current value sufficient to eliminate the charge side polarization generated in the battery immediately before the discharge is performed. An estimated voltage estimating means for estimating an estimated voltage of the battery;
And further adding the remaining voltage drop value stored in the remaining voltage drop value storage means to the estimated voltage value of the battery estimated by the estimated voltage estimation means, The battery capacity calculating device according to claim 7, wherein the battery capacity is calculated. Open circuit voltage value storage means for storing the value of the open circuit voltage;
Equilibrium state determining means for determining whether or not the battery is in an equilibrium state;
At the time of constant load discharge from the battery determined to be in an equilibrium state by the equilibrium state determination means at a current value sufficient to eliminate the charge side polarization generated in the battery at least immediately before the discharge, the estimation A residual voltage drop value calculating means for subtracting the estimated voltage value of the battery estimated by the voltage estimating means from the open circuit voltage value stored in the open circuit voltage value storage means to obtain the residual voltage drop value; ,
The battery capacity calculation device according to claim 8, further comprising: the remaining voltage drop value storing unit that stores the remaining voltage drop value obtained by the remaining voltage drop value calculating unit. Balanced state terminal voltage measuring means for measuring the terminal voltage of the battery in a state determined to be in an equilibrium state by the equilibrium state determining means;
An open circuit voltage update means for updating the value of the open circuit voltage stored in the open circuit voltage value storage means to the value of the terminal voltage of the battery measured by the balanced terminal voltage measurement means;
The battery capacity calculating device according to claim 9, further comprising: Temperature detecting means for detecting the ambient temperature of the battery;
At the time when the estimated voltage estimating means estimates the estimated voltage of the battery, the ambient temperature of the battery detected by the temperature detecting means, and the time when the balanced terminal voltage measuring means measures the terminal voltage of the battery, The presence or absence of a difference with the ambient temperature of the battery detected by the temperature detection means is confirmed, and if there is a difference, the residual voltage drop value stored in the residual voltage drop value storage means according to the temperature difference Correction means for correcting
And when the residual voltage drop value is corrected by the correcting means, the corrected residual voltage drop value is added to the estimated voltage value of the battery estimated by the estimated voltage estimating means. The battery capacity calculating device according to claim 10, wherein the current charging capacity of the battery is calculated. The current value sufficient to eliminate the charge side polarization generated in the battery immediately before discharging is a predetermined large current value required when starting the cell motor of the vehicle, and the discharge current decrease start detecting means is In the constant load discharge of the battery, it is configured to detect that the discharge current of the battery starts to decrease from the predetermined large current value, and that the discharge current of the battery starts to decrease from the predetermined large current value. Discharge for detecting that the discharge current of the battery detected by the discharge current decrease start detecting means has decreased to a target current value that is equal to or greater than the maximum discharge current value when the vehicle load other than the cell motor is being driven. And further comprising a current drop detecting means, wherein the characteristic indexing means starts the reduction of the discharge current when the discharge current of the battery starts to decrease from the predetermined large current value. The voltage-current is detected from the terminal voltage and the discharge current of the battery that are periodically measured until the discharge current drop detecting means detects that the current value has decreased to the target current value after the detecting means detects. battery capacity calculation device according to one wherein either claims 8, 9, 10 or 11 obtains the equation representing the characteristic.

Images