JP3869666B2

JP3869666B2 - Vehicle battery charge state measuring method and apparatus

Info

Publication number: JP3869666B2
Application number: JP2001042053A
Authority: JP
Inventors: 正志長尾; 英明蒲原; 洋一荒井
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2001-02-19
Filing date: 2001-02-19
Publication date: 2007-01-17
Anticipated expiration: 2021-02-19
Also published as: JP2002240657A

Description

【０００１】
【発明の属する技術分野】
本発明は、ガソリンや軽油等を燃料とするエンジンを動力源として走行する車両に搭載され、エンジンを始動するためのセルモータに対し、エンジン始動時に電力供給するバッテリの充電状態を測定する車両用バッテリ充電状態測定方法及び装置に関するものである。
【従来の技術】
【０００２】
エンジンを動力源として走行する車両においては、エンジンの回転中、その動力を受けて交流発電するオルターネータが備えられているので、エンジンの回転中は、負荷に供給される電力はオルターネータの発電する交流を整流したものが主に使用され、バッテリから電力供給されることが少ない。むしろ、負荷に供給される電力量がオルターネータの発電量よりも小さく、余剰の電力があるときには、満充電状態にないバッテリが充電される。したがって、バッテリは通常満充電状態に近い状態に保持されるようになっている。
【０００３】
しかし、エンジンを回転しない状態での負荷への電力供給が続いた場合には、負荷への電力供給が専らバッテリから行われるので、バッテリの放電可能容量が減少するようになる。このような状況は、例えば、一定時間を超える停車毎にエンジンを停止してエンジンを再始動するためにセルモータを頻繁に回転させることを必要とするアイドリングストップ車において、エンジンを回転している時間の割に、すなわち、走行距離の割にセルモータによりエンジン起動する頻度が高い場合に起こりうる。
【０００４】
また、オルターネータの発電量を上回る電力供給が続いた場合にも、足りない分をバッテリからの放電によりまかなうので、バッテリの放電可能容量が減少するようになる。このような状況は、例えば、渋滞時のようにエンジン回転数が上がらず、発電量も少ない状態で大きな負荷への電力供給が長時間続いた場合に起こりうる。
【０００５】
セルモータは比較的大きな負荷であってその動作開始時に大電流を供給する必要があるので、バッテリの放電可能容量が減少し、バッテリの端子電圧が低下して最大放電電流も低下してしまうと、一度停車した後に、セルモータを回転させて、エンジンを再始動できなくなることが起こる。したがって、アイドリングストップ車に限らず、エンジンを動力源とする車両においては、エンジンを始動できるかどうかを判断することが重要であり、この判断を行うためにはバッテリから取り出せる電気量、すなわち、放電可能容量を知る必要がある。
【０００６】
バッテリの充電状態を知るための方法には、バッテリの端子電圧を測定する電圧測定方式、バッテリ電解液の比重を測定する電解液比重測定方式、バッテリの充放電電流を積算する電流積算（電力積算）方式などがある。
【０００７】
【発明が解決しようとする課題】
しかしながら、電圧測定方式においては、電流の大きさによって電圧が変化し、放電電流を安定させない限り端子電圧も安定しないので、現実には、バッテリの充電状態と相関のある端子電圧を測定により得ることは期待できない。電解液比重測定方式においては、バッテリの電解液比重と充電状態との間には一定の直線的な相関があるので、電解液比重を測定すればバッテリの充電状態を把握することができるはずであるが、実際には、充放電中や充放電の終了直後のバッテリにおいては、電解液と電極との間で発生した化学反応により電解液の比重が不均一となってしまうので、正確な電解液比重を測定してバッテリの充電状態を正確に把握することができない。
【０００８】
この点、電流積算（電力積算）方式は、上述した電圧測定方式や電解液比重測定方式のような問題がなく、バッテリの充放電される電気量を積算するものであるので、電気量（Ａｈ）で表されるバッテリの容量を求めるのに都合がよいとの理由から、充放電を伴うバッテリ使用中の充電状態を求める場合の主流となっている。
【０００９】
すなわち、電流積算方式では、車載バッテリがその種類に応じた満充電状態でのＡｈ値Ｘが予め分かっており、また、Ａｈ値が予め定めた値Ｙ以下になったときそれ以上の放電をすべきでないことも分かっているので、Ｘを充電状態１００％、Ｙを充電状態０％とし、１％当たりのＡｈ値Ｚを（Ｘ−Ｙ）／１００を予め求めておくとともに、充電電流Ｉｊと放電電流Ｉｄを一定時間間隔で測定し、各測定値に一定時間ｔを乗じたＡｈ値を加算したり減算して求めた積算値が±Ａｈ値Ｚ以上となる毎に％で表された現在の充電状態ｘに±１することによってバッテリ使用中の充電状態を求めるようにしたものである。
【００１０】
しかしながら、この方式の場合、積算すべきバッテリの充放電電流を正確に測定できていないとき、僅かの誤差であっても、長期間にわたって連続的に積算することによって誤差が累積し、求めたバッテリの充電状態が現状と大きくかけ離れてしまい、結果的に、バッテリの充電状態を正確に把握することができなくなってしまう問題がある。
【００１１】
そこで、バッテリが例えば少なくとも１日以上使用されておらず平衡状態にあるとき、その状態での開回路端子電圧を測定し、この測定した開回路端子電圧を利用して充電状態が求められたときには、積算方式によって求めた充電状態を開回路端子電圧により求めた充電状態によって更新し、積算方式により求めた充電状態を表す値に累積した誤差をキャンセルすることが行われる。
【００１２】
しかし、バッテリの個体差や劣化の進行度合い等によってバッテリの開回路端子電圧が変化してしまい、この開回路端子電圧を利用して求めた充電状態自体が信頼できないものとなってしまう。また、長い期間にわたって平衡状態になることがないとき、すなわち、充放電が行われないバッテリ未使用状態になっても、その期間が短い場合には、累積した誤差をキャンセルする頻度が極めて少なくなり、大きな累積誤差を含んだままの充電状態しか知り得ない状態に置かれることになり、バッテリの現在の充電状態が正確なものでなくなるという問題もある。
【００１３】
よって本発明は、上述した現状に鑑み、バッテリの個体差や劣化の進行度合い等によって変化する充電状態を正確に割り出し積算すべき元々のバッテリの充電状態をより正確に測定できるようにして、バッテリの充電状態をより正確に測定できるようにした車両用バッテリ充電状態測定方法と、この方法を実施する際に用いて好適な車両用バッテリ充電状態測定装置とを提供することを課題としている。
【００１４】
よって本発明は、上述した現状に鑑み、充放電電流を長期間にわたって連続的に積算することによる大きな累積誤差の発生を生じ難くして、バッテリの充電状態をより正確に測定できるようにした車載用バッテリ充電状態測定方法と、この方法を実施する際に用いて好適な車両用バッテリ充電状態測定装置とを提供することを課題としている。
【００１５】
【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５記載の本発明は、車両用バッテリ充電状態測定方法に関するものであり、請求項６乃至請求項１０記載の本発明は、車両用バッテリ充電状態測定装置に関するものである。
【００１６】
そして、請求項１に記載した本発明は、エンジンを動力源として走行する車両に搭載されて使用されるバッテリの充電電流及び放電電流をそれぞれ周期的に測定し、該周期的に測定した前記充電電流の前記バッテリの現在の充電状態に対する加算及び前記周期的に測定した前記放電電流の前記バッテリの現在の充電状態からの減算をそれぞれ行ってバッテリの充電状態を測定する車両用バッテリ充電状態測定方法において、各種の容量におけるバッテリの電圧−電流特性を表す式に基づいて、容量に対して電圧が直線的に変化する電流の値を仮想電流として予め求めておき、平衡状態の前記バッテリの端子電圧を開回路電圧として測定し、該測定した開回路電圧に基づいて前記バッテリの残存容量を演算し、該演算により求めた前記残存容量を用いて前記現在の充電状態を更新して設定し、平衡状態の前記バッテリによる定負荷への放電時に、その初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、前記バッテリの端子電圧と放電電流を周期的に測定し、該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の相関を示す電圧−電流特性を表す式に前記仮想電流を代入して求めた前記定負荷の放電時における前記バッテリの推定電圧の値と前記開回路電圧の値との差値を、前記バッテリによる定負荷への放電時の初期段階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の差である残存電圧降下差値として予め求めておき、非平衡状態の前記バッテリによる前記定負荷への放電毎に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間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−電流特性を表す式を求め、該求めた電圧−電流特性を表す式に前記仮想電流を代入して求めた前記バッテリの現在の推定電圧の値に前記予め求めた残存電圧降下差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算した前記バッテリの残存容量を用いて前記現在の充電状態を更新して設定するようにしたことを特徴とする車両用バッテリ充電状態測定方法に存する。
【００１７】
請求項１に記載した本発明によれば、エンジンを動力源として走行する車両に搭載されて使用されるバッテリの充電電流及び放電電流をそれぞれ周期的に測定し、この周期的に測定した充電電流のバッテリの現在の充電状態に対する加算及び周期的に測定した放電電流のバッテリの現在の充電状態からの減算をそれぞれ行って電流積算方式によってバッテリの充電状態を測定するものであって、車両の走行中のように充放電電流の変化する中で、測定した充放電電流を加算及び減算することでバッテリの充電状態を測定できる。
【００１８】
そして、平衡状態のバッテリによる定負荷への放電時に、この放電の開始前のバッテリの端子電圧である開回路電圧を測定し、この測定した開回路電圧に基づいてバッテリの残存容量を演算し、この演算により求めた残存容量を用いて現在の充電状態を更新して設定するので、平衡状態のバッテリによる定負荷への放電時毎に、電流積算方式によって求めた充電状態に累積する誤差を解消できる。
【００１９】
また、平衡状態のバッテリによる定負荷への放電時に、その初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、バッテリの端子電圧と放電電流を周期的に測定して、この周期的に測定したバッテリの端子電圧と放電電流との相関を示す電圧−電流特性を表す式に仮想電流を代入して求めた定負荷の放電時における前記バッテリの推定電圧の値と開回路電圧の値との差値を、前記バッテリによる定負荷への放電時の初期段階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の差である残存電圧降下差値として予め求めておく。この残存電圧降下差値は、推定電圧が放電開始直前の開回路電圧にほぼ等しくなるべきなのが、種々の要因によって、等しくならない場合のその差の大きさを表すもので、推定電圧から開回路電圧を推定するにはこの差値分で推定電圧を修正することで開回路電圧が推定できることになる。
【００２０】
そして、非平衡状態のバッテリによる定負荷への放電毎に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間中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電圧−電流特性を表す式を求め、この電圧−電流特性を表す式に仮想電流を代入してバッテリの現在の推定電圧を推定する。
【００２１】
非平衡状態からの放電であっても、その初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する放電である場合、この放電によって生じる分極成分による電圧降下値は、平衡状態のバッテリによる定負荷への放電時に生じる上記残存電圧降下値と等しくなるので、上記推定したバッテリの現在の推定電圧の値に予め求めた残存電圧降下差値を加算することによって推定の開回路電圧が求まり、この推定開回路電圧に基づいてバッテリの残存容量を演算し、この演算により求めた残存容量を用いて現在の充電状態を更新して設定する。
【００２２】
したがって、非平衡状態であっても放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する放電毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００２３】
また、請求項２に記載した本発明は、請求項１記載の車両用バッテリ充電状態測定方法において、前記定負荷が前記車両のエンジンを始動させるためのセルモータであることを特徴とする車両用バッテリ充電状態測定方法に存する。
【００２４】
請求項２に記載した本発明によれば、定負荷が車両のエンジンを始動させるためのセルモータであるので、請求項１記載の発明の作用に加え、エンジンの始動時毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００２５】
また、請求項３に記載した本発明は、請求項１又は２記載の車両用バッテリ充電状態測定方法において、非平衡状態の前記バッテリによる前記定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷への放電毎に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間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−電流特性を表す式を求め、該求めた電圧−電流特性を表す式に前記仮想電流値を代入して求めた前記バッテリの現在の推定電圧の値に前記予め求めた残存電圧降下差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算した前記バッテリの残存容量を用いて前記現在の充電状態を更新して設定するようにしたことを特徴とする車両用バッテリ充電状態測定方法に存する。
【００２６】
請求項３に記載した本発明によれば、非平衡状態からの放電が定負荷以外の他の負荷への放電であっても、他の負荷が定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少するものである場合には、この放電によって生じる分極成分による電圧降下値は、平衡状態のバッテリによる定負荷への放電時に生じる上記残存電圧降下値と等しくなるので、請求項１又は２記載の発明の作用に加え、上記推定したバッテリの現在の推定電圧の値に予め求めた残存電圧降下差値を加算することによって推定の開回路電圧が求まり、この推定開回路電圧に基づいてバッテリの残存容量を演算し、この演算により求めた残存容量を用いて現在の充電状態を更新して設定する。
【００２７】
したがって、非平衡状態であって、しかも、定負荷に対する放電でなくても、定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷に対する放電毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００２８】
また、請求項４に記載した本発明は、請求項３記載の車両用バッテリ充電状態測定方法において、前記他の負荷が、点灯時にラッシュ電流の流れるヘッドランプ、走行用動力源としてのエンジンを補助するため前記車両が補助駆動源として有する、駆動時にラッシュ電流の流れる駆動モータの少なくとも１つであることを特徴とする車両用バッテリ充電状態測定方法に存する。
【００２９】
請求項４に記載した本発明によれば、他の負荷が点灯時にラッシュ電流の流れるヘッドランプ、走行用動力源としてのエンジンを補助するため前記車両が補助駆動源として有する、駆動時にラッシュ電流の流れる駆動モータの少なくとも１つであるので、請求項３記載の発明の作用に加え、少なくともヘッドランプの点灯又は駆動モータの駆動時毎にも、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００３０】
また、請求項５に記載した本発明は、請求項１〜４のいずれかに記載の車両用バッテリ充電状態測方法において、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を最新の所定時間分収集して格納、記憶しておき、該記憶しておいた最新の所定時間分の前記バッテリの端子電圧と放電電流とを用いて、放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中の前記電圧−電流特性を表す式を求めることを特徴とする車両用バッテリ充電状態測定方法に存する。
【００３１】
請求項５に記載した本発明によれば、周期的に測定したバッテリの端子電圧と放電電流とを最新の所定時間分収集して格納、記憶しておき、この記憶しておいた最新の所定時間分のバッテリの端子電圧と放電電流とを用いて、所定値から減少している間の電圧−電流特性を表す式を求ているので、請求項１〜４のいずれかに記載の発明の作用に加え、電圧−電流特性を表す式を求めるための処理を任意時点で行えるようになる。
【００３２】
また、請求項６に記載した本発明は、図１の基本構成図に示すように、エンジンを動力源として走行する車両に搭載されて使用されるバッテリ１３の充電電流及び放電電流をそれぞれ周期的に測定する電流測定手段２３ａ−１と、該電流測定手段によって周期的に測定した前記充電電流の前記バッテリの現在の充電状態に対する加算及び前記電流測定手段により周期的に測定した前記放電電流の前記バッテリの現在の充電状態からの減算をそれぞれ行ってバッテリの充電状態を測定する積算式充電状態測定手段２３ａ−２とを備える車両用バッテリ充電状態測定装置において、前記バッテリの端子電圧を測定する電圧測定手段２３ａ−３と、前記電圧測定手段及び前記電流測定手段によってそれぞれ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これらの端子電圧と放電電流との相関を示す電圧−電流特性を表す式を決定する電圧−電流特性決定手段２３ａ−４と、前記電圧測定手段により平衡状態の前記バッテリの端子電圧を開回路電圧として測定し、該測定した開回路電圧に基づいて前記バッテリの残存容量を演算し、該演算により求めた前記残存容量を用いて前記現在の充電状態を更新して設定する第１の充電状態更新設定手段２３ａ−５と、平衡状態の前記バッテリによる定負荷５への放電時に、その初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、前記電圧測定手段及び前記電流測定手段によってそれぞれ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これらの端子電圧と放電電流との相関を示す電圧−電流特性を表す式を前記電圧−電流特性決定手段に決定させ、前記電圧−電流特性決定手段が決定した電圧−電流特性を表す式に、各種の容量におけるバッテリの電圧−電流特性を表す式に基づいて仮想電流として予め求めてた容量に対して電圧が直線的に変化する電流の値を代入して前記定負荷の放電時における前記バッテリの推定電圧の値と前記開回路電圧の値との差値を、前記バッテリによる定負荷への放電時の初期段階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の差である残存電圧降下差値として記憶する残存電圧降下差値記憶手段２３ａ−６と、非平衡状態の前記バッテリによる前記定負荷への放電毎に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、前記電圧測定手段及び前記電流測定手段によってそれぞれ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−電流特性を表す式を前記電圧−電流特性決定手段に決定させ、前記電圧−電流特性決定手段が決定した電圧−電流特性を表す式に前記仮想電流を代入して求め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差値記憶手段に予め記憶した残存電圧降下差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算した前記バッテリの残存容量を用いて前記現在の充電状態を更新して設定する第２の充電状態更新設定手段２３ａ−７とを備えることを特徴とする車両用バッテリ充電状態測定装置に存する。
【００３３】
請求項６に記載した本発明によれば、車両用バッテリ充電状態測定装置は、電流測定手段２３ａ−１がエンジンを動力源として走行する車両に搭載されて使用されるバッテリ１３の充電電流及び放電電流をそれぞれ周期的に測定し、積算式充電状態測定手段２３ａ−２が電流測定手段によって周期的に測定した充電電流のバッテリの現在の充電状態に対する加算及び周期的に測定した放電電流のバッテリの現在の充電状態からの減算をそれぞれ行ってバッテリの充電状態を測定するものであって、車両の走行中のように充放電電流の変化する中で、測定した充放電電流を加算及び減算することでバッテリの充電状態を測定できる。
【００３４】
そして、第１の充電状態更新設定手段２３ａ−５が、電圧測定手段２３ａ−３により平衡状態のバッテリの端子電圧を開回路電圧として測定し、この測定した開回路電圧に基づいてバッテリの残存容量を演算し、この演算により求めた残存容量を用いて現在の充電状態を更新して設定するので、平衡状態のバッテリによる定負荷への放電毎に、積算式充電状態測定手段により電流積算方式によって求めた充電状態に累積する誤差を解消できる。
【００３５】
また、残存電圧降下値記憶手段２３ａ−６が、平衡状態のバッテリによる定負荷への放電時に、その初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、電圧測定手段２３ａ−３及び電流測定手段２３ａ−１によってそれぞれ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電圧−電流特性決定手段２３ａ−４が決定するこれらの端子電圧と放電電流との相関を示す電圧−電流特性を表す式に、各種の容量におけるバッテリの電圧−電流特性を表す式に基づいて仮想電流として予め求めてた容量に対して電圧が直線的に変化する電流の値を代入して所定の大電流値による定負荷の放電時におけるバッテリの推定電圧の値と開回路電圧の値との差値を、バッテリによる定負荷への放電時の初期段階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の差である残存電圧降下差値として記憶しているが、この残存電圧降下差値は、推定電圧が放電開始直前の開回路電圧にほぼ等しくなるべきなのが、種々の要因によって、等しくならない場合のその大きさの差を表すもので、推定電圧から開回路電圧を推定する際にこの差値で推定電圧を修正することで開回路電圧を正しく推定できることになる。
【００３６】
そして、第２の充電状態更新設定手段２３ａ−７が、非平衡状態のバッテリによる定負荷への放電時に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、電圧測定手段及び電流測定手段によってそれぞれ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電圧−電流特性を表す式を電圧−電流特性決定手段２３ａ−４に決定させ、電圧−電流特性決定手段２３ａ−４が決定した電圧−電流特性を表す式に仮想電流を代入して求めたバッテリの現在の推定電圧の値に差値記憶手段２３ａ−６に予め記憶した差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算したバッテリの残存容量を用いて現在の充電状態を更新して設定する。
【００３７】
したがって、非平衡状態であってもバッテリによる定負荷への放電毎に、第２の充電状態更新設定手段２３ａ−５によって、種々の要因によって発生する推定電圧と開回路電圧との間の差を補正した推定開回路電圧に基づいて、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００３８】
また、請求項７に記載した本発明は、請求項６記載の車両用バッテリ充電状態測定装置において、前記定負荷が前記車両のセルモータであることを特徴とする車両用バッテリ充電状態測定装置に存する。
【００３９】
請求項７に記載した本発明によれば、定負荷が前車両のセルモータ５であるので、請求項６記載の発明の作用に加え、エンジンの始動時毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００４０】
また、請求項８に記載した本発明は、請求項６記載の車両用バッテリ充電状態測装置において、前記第２の充電状態更新設定手段は、非平衡状態の前記バッテリによる前記定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷への放電毎に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、前記電圧測定手段及び前記電流測定手段によってそれぞれ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−電流特性を表す式を前記電圧−電流特性決定手段に決定させ、前記電圧−電流特性決定手段が決定した電圧−電流特性を表す式に前記仮想電流値を代入して求め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差値記憶手段に予め記憶した残存電圧降下差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算した前記バッテリの残存容量を用いて前記現在の充電状態を更新して設定することを特徴とする車両用バッテリ充電状態測定装置に存する。
【００４１】
請求項８に記載した本発明によれば、第２の充電状態更新設定手段２３ａ−７が、非平衡状態のバッテリによる定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷への放電時に、放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、電圧測定手段及び電流測定手段によってそれぞれ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電圧−電流特性を表す式を電圧−電流特性決定手段２３ａ−４に決定させ、電圧−電流特性決定手段２３ａ−４が決定した電圧−電流特性を表す式に仮想電流値を代入して求めたバッテリの現在の推定電圧の値に残存電圧降下差値記憶手段２３ａ−６に予め記憶した残存電圧降下差値を加算して推定開回路電圧を求め、該求めた推定開回路電圧に基づいて演算したバッテリの残存容量を用いて現在の充電状態を更新して設定する。
【００４２】
したがって、非平衡状態であって、しかも、定負荷に対する放電でなくても、定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷への放電毎に、第２の充電状態更新設定手段２３ａ−５によって、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００４３】
また、請求項９に記載した本発明は、請求項８記載の車両用バッテリ充電状態測定装置において、前記他の負荷が、点灯時にラッシュ電流の流れるヘッドランプ、走行用動力源としてのエンジンを補助するため前記車両が補助駆動源として有する、駆動時にラッシュ電流の流れる駆動モータの少なくとも１つであることを特徴とする車両用バッテリ充電状態測定装置に存する。
【００４４】
請求項９に記載した本発明によれば、定負荷が点灯時にラッシュ電流の流れるヘッドランプ、走行用動力源としてのエンジンを補助するため前記車両が補助駆動源として有する、駆動時にラッシュ電流の流れる駆動モータの少なくとも１つであるので、請求項８記載の発明の作用に加え、少なくともヘッドランプの点灯又は駆動モータの駆動時毎にも、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる。
【００４５】
また、請求項１０に記載した本発明は、請求項６〜９のいずれかに記載の車両用バッテリ充電状態測装置において、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を最新の所定時間分収集して格納、記憶する測定電圧・電流記憶手段２３ｂを備え、前記電圧−電流特性決定手段が、前記測定電圧・電流記憶手段に記憶しておいた最新の所定時間分の前記バッテリの端子電圧と放電電流とを用いて前記電圧−電流特性を表す式を求めることを特徴とする車両用バッテリ充電状態測定装置に存する。
【００４６】
請求項１０に記載した本発明によれば、測定電圧・電流記憶手段２３ｂが、周期的に測定したバッテリの端子電圧と放電電流とを最新の所定時間分収集して格納、記憶し、電圧−電流特性決定手段２３ａ−４が、測定電圧・電流記憶手段に記憶しておいた最新の所定時間分のバッテリの端子電圧と放電電流とを用いて電圧−電流特性を表す式を求めているので、請求項６〜９記載の発明の作用に加え、放電電流が所定値から減少している間の電圧−電流特性を表す式を電圧−電流特性決定手段が求めるための処理を任意時点で行えるようになる。
【００４７】
【発明の実施の形態】
以下、本発明による車両用バッテリ充電状態測定方法を、本発明による車両用バッテリ充電状態測定装置と共に、図２を参照して説明するが、その前に、バッテリそのものの特性について検討する。
【００４８】
まず、バッテリの端子電圧はそのバッテリの様々な条件を含んだバッテリの状態を表していることに着目し、バッテリの個体差や劣化の進行度合い等によって変化する充電容量を正確に割り出して、積算すべき元々のバッテリの充電状態をより正確に測定できるようにするために、車両走行中に激しく変化するバッテリの端子電圧から安定した電圧を推定できるようにする方法について、その詳細を以下説明する。
【００４９】
ところで、図３の特性図に示すように、バッテリを１０Ａ刻みで１０〜８０（Ａ）の各定電流にて放電させると、放電時間（横軸）とバッテリの端子電圧（Ｖ：縦軸）との相関は、放電電流が小さいほど放電時間が長い点において相互に異なっているが、放電時間が経過するにつれてバッテリの端子電圧が急激に降下する点において共通している。
【００５０】
図３の特性図において、横軸は時間であるが、定電流放電であることと、バッテリ容量が電気量（Ａｈ）で表されることとを考慮すると、この横軸はバッテリ容量と見ることができる。
【００５１】
そこで、図３の特性図を、定電流放電時における横軸のバッテリ容量と縦軸の端子電圧との相関として見ると、放電電流が小さいほど大きな電力を取り出すことができ、かつ、縦軸側に近いバッテリの満充電状態の付近では容量降下が遅く、縦軸から図３中右側に離れて放電終止電圧に近づくほど急激に容量が降下してしまうことが判る。
【００５２】
以上のことから、仮に放電電流を安定させることができたとしても、バッテリの充電容量と端子電圧との間には直線的な相関がないので、バッテリの端子電圧から充電容量を求めることはできないことが判る。
【００５３】
そこで注目されるのは、ほぼ直線的な相関があるバッテリの電解液比重と開回路電圧との関係と、同じく直線的な相関があるバッテリの電解液比重と充電状態との関係から、直線的な相関が成り立つはずの、バッテリの充電状態と開回路電圧との関係を利用する容量演算方式である。
【００５４】
ただし、この容量演算方式の唯一の弱点は、バッテリの開回路電圧を測定できるのが、自然放電を除くと充電状態に変化のない非放電時に限られることであり、換言すると、充電状態に変化の生じる放電時、すなわち、バッテリ使用時にはバッテリの開回路電圧を測定することができないことである。
【００５５】
したがって、バッテリの充電状態と開回路電圧との関係を利用する容量演算方式を用いる上での最大のポイントは、バッテリの放電時に如何にして開回路電圧を見つけるか、ということになる。
【００５６】
ところで、バッテリの放電時に測定できるのは、バッテリの端子電圧と放電電流であるが、図４の特性図から、バッテリの充電状態が変わらなくても放電電流が上がればバッテリの端子電圧が下がるのは明らかであるから、端子電圧と放電電流との間には、負の相関を示す電圧−電流特性（Ｉ−Ｖ特性）があり、また、この電圧−電流特性は、バッテリの充電状態が変わると変化することが判る。
【００５７】
そこで、バッテリの電圧−電流特性をバッテリの充電状態に応じて複数求めるために、次のような測定を行う。
【００５８】
まず、或る電流Ｉ_aとこの電流Ｉ_aよりも低い電流Ｉ_bとが周期的に交互に現れるパルス状の電流によるバッテリの放電を連続して行い、そのときに放電電流とは逆位相で現れるバッテリの端子電圧と放電電流との組（Ｉ_a，Ｖ₁）、（Ｉ_b，Ｖ₂）、（Ｉ_a，Ｖ₃）、（Ｉ_b，Ｖ₄），…を、放電電流のパルス周期（例えば１ｍｓ）に同期し連続して所定数（例えば１００サンプル）サンプリングする。
【００５９】
そして、所定数サンプリングしたバッテリの端子電圧と放電電流との組（Ｉ_a，Ｖ₀₁）、（Ｉ_b，Ｖ₀₂）、（Ｉ_a，Ｖ₀₃）、（Ｉ_b，Ｖ₀₄），…から、最小二乗法により、Ｖ＝ａ₁Ｉ＋ｂ₁なるバッテリの直線的な電圧−電流特性式における係数ａ₁，ｂ₁を得て、この式Ｖ＝ａ₁Ｉ＋ｂ₁を、上記したサンプリングの間における容量に対応したバッテリの電圧−電流特性として位置づける。
【００６０】
次に、上記と同様の放電によって、パルス状の電流Ｉ_a，Ｉ_aによるバッテリの放電を連続して行い、そのときに放電電流とは逆位相で現れるバッテリの端子電圧と放電電流との組（Ｉ_a，Ｖ₁₁）、（Ｉ_b，Ｖ₁₂）、（Ｉ_a，Ｖ₁₃）、（Ｉ_b，Ｖ₁₄），…を連続して所定数サンプリングし、これらから、最小二乗法により、Ｖ＝ａ₂Ｉ＋ｂ₂なるバッテリの直線的な電圧−電流特性式における係数ａ₂，ｂ₂を得て、この式Ｖ＝ａ₂Ｉ＋ｂ₂を、上記したサンプリングの間における容量に対応したバッテリの電圧−電流特性として位置づける。
【００６１】
以後、同様にして、Ｖ＝ａ_nＩ＋ｂ_nなるバッテリの直線的な電圧−電流特性式における係数ａ_n，ｂ_nを得て、この式Ｖ＝ａ_nＩ＋ｂ_nを、バッテリの徐々に減少する互いに異なる容量に対応した電圧−電流特性として位置づけることで、１００％から０％までの各容量に対応したバッテリの電圧−電流特性を得る。
【００６２】
なお、各所定数サンプリングしたバッテリの端子電圧と放電電流との組（Ｉ_a，Ｖ_n1）、（Ｉ_b，Ｖ_n2）、（Ｉ_a，Ｖ_n3）、（Ｉ_b，Ｖ_n4），…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Ｖ＝ａ_nＩ＋ｂ_nとの関係を、図４に模式的に示した。
【００６３】
ここで、上述のようにして得た各容量に応じたバッテリの電圧−電流特性式に、仮想の定電流値である仮想電流値Ｉｓを各々代入し、それによって求まるＶを、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Ｖｎと定義すると、図５のグラフに示すような定電流放電特性が得られる。
【００６４】
そして、仮想電流値Ｉｓとして正のいずれの値を代入しても、その仮想電流値Ｉｓによる定電流放電特性は、横軸に取った容量が図５中右側に進んで０に近づくにつれて推定電圧Ｖｎが急激に低下する非直線的な特性となり、理論上開回路電圧を示すはずの仮想電流値Ｉｓ＝０Ａの場合においても、定電流放電特性は同様の特性を示すことが判る。
【００６５】
ただし、図５のグラフによれば、仮想電流値Ｉｓが小さければ小さいほど、容量が０に近づくにつれて推定電圧Ｖｎが低下する度合いが小さくなっているため、あくまで仮想の領域であるが、上述のようにして得た各容量に応じたバッテリの電圧−電流特性式に仮想電流値Ｉｓとして負の値を代入して、その負の値の仮想電流値Ｉｓによる定電流放電特性をグラフに示すと、図６に示すように、図示のグラフの場合においては、仮想電流値Ｉｓ＝−１０Ａを境に、容量０に近い領域の推定電圧Ｖｎの特性変化が変曲する。当然のことながら、図示の特性と異なる特性を有するバッテリでは、仮想電流値Ｉｓの値は−１０Ａ以外の値になる。
【００６６】
したがって、理論上では、仮想電流値Ｉｓを−１０Ａとすると、定電流放電における推定電圧Ｖｎがバッテリの容量に対して直線的な特性を示すことになる。
【００６７】
そこで、上述のようにして得た各容量に応じたバッテリの電圧−電流特性を、縦軸を放電電流Ｉとし横軸を端子電圧Ｖとした図７のグラフ上において、定電流放電における推定電圧Ｖｎがバッテリの容量に対して直線的な特性を示すことを検証してみる。
【００６８】
まず、各電圧−電流特性式の傾きを表す係数ａ₁，ａ₂，…，ａ_nが各々異なり、かつ、各電圧−電流特性式の切片を表す係数ｂ₁，ｂ₂，…，ｂ_nも各々異なることから、図７中の現実に存在する正の放電電流領域においては、バッテリ容量の変化に対して端子電圧Ｖが直線的に変化する放電電流値Ｉは存在しない。
【００６９】
しかし、図７中の想像上の領域である負の放電電流領域においては、放電電流値Ｉ＝−１０Ａの時に、バッテリの容量に対して端子電圧Ｖが直線的に変化する特性を示すことになり、この放電電流値Ｉ＝−１０Ａにおける各容量に対応するバッテリの端子電圧Ｖが、推定電圧Ｖｎであるということになる。
【００７０】
そこで、この仮想電流値Ｉｓ＝−１０Ａにおけるバッテリの容量とこれに対して直線的な相関を有する推定電圧Ｖｎとの関係をグラフに表すと、図８に示すように、縦軸の満充電時の開回路電圧Ｖｓと放電終止時の開回路電圧Ｖｅとの間に推定電圧Ｖｎが存在することになり、この推定電圧Ｖｎに対応する横軸の容量上の値が、バッテリの残存容量、つまり、充電状態ＳＯＣ（State of charge ）ということになる。
【００７１】
したがって、推定電圧Ｖｎはバッテリの開回路電圧に代わるものであるということができ、開回路電圧が測定できない放電時においても、その放電が、電力を供給する負荷が放電中に変化しない定負荷放電であれば、その放電中に微妙に変動するバッテリの端子電圧と放電電流とを測定することで、その定負荷放電におけるバッテリの端子電圧と放電電流との相関である電圧−電流特性を求めて、その特性式（Ｖ＝ａＩ＋ｂ）に予め求めておいた仮想電流値Ｉｓ＝−１０Ａを代入して推定電圧Ｖｎを求めることで、この推定電圧Ｖｎからバッテリの充電状態ＳＯＣを求めることができる。
【００７２】
そして、図８の縦軸上における推定電圧Ｖｎと満充電時の開回路電圧Ｖｓとの比に換算して、満充電容量に対する現在の充電状態ＳＯＣを求めると、
ＳＯＣ＝｛（Ｖｎ−Ｖｅ）／（Ｖｓ−Ｖｅ）｝×１００（％）
となる。
【００７３】
しかし、正確を期して、電力（Ｖ×Ａｈ）の比に換算して満充電容量に対する現在の充電状態ＳＯＣを求めると、

となる。
【００７４】
ところで、バッテリの放電中には、図９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。
【００７５】
特に、図９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。
【００７６】
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予め定めた仮想電流を用いて推定電圧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の大きさ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。
【００７７】
なお、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。このとき、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、分極による電圧降下の大きさの差による影響を排除した推定電圧を求めることで、バッテリの充電状態を正確に測定することができれば、この時点で、測定したバッテリの充電状態を、それまで積算方式によって求めたバッテリの充電状態に代えて利用することによって、長期間にわたって連続的に積算して大きな誤差が累積しないようにできるとともに、バッテリの個体差や劣化の進行度合い等によって変化する充電容量を正確に割り出して、バッテリの充電状態をより正確に測定できるようになる。したがって、このようなことを可能にした車両用バッテリ充電状態測定方法及び装置の具体的な実施の形態を、図２に戻って以下説明する。
【００７８】
図２は本発明の車両用バッテリ充電状態測定方法を適用した本発明の一実施形態に係る車両用バッテリ充電状態測定装置の概略構成を一部ブロックにて示す説明図であり、図中符号１で示す本実施形態の車両用バッテリ充電状態測定装置は、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。
【００７９】
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。
【００８０】
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。
【００８１】
なお、モータジェネレータ５はさらに、図示しない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には、短時間に大きな電流が流される。この電流はラッシュ電流と呼ばれるもので、このときモータジェネレータ５は、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定常状態よりも多くの電力を単独で消費する。
【００８２】
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、図示しない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。）等が定常作動している場合、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例えば３５Ａ（アンペア）に満たない。
【００８３】
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、例えば２５０Ａ（アンペア）に達するラッシュ電流がバッテリ９から瞬時的に流れる。同様のことは、パワーウインドスイッチやライティングスイッチのオン操作によって、比較的大きな負荷であるパワーウインドやヘッドライトの起動時やオン時にも、セルモータとして用いられるモータジェネレータ５と同じとはならないが、モータジェネレータ５に流れるものに近い大きなラッシュ電流が瞬時的に流れる。
【００８４】
したがって、本実施形態の車両用バッテリ充電状態測定装置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、及び、この定負荷放電に類似した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。
【００８５】
なお、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。また、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おいて、パワーウインドスイッチやライティングスイッチのオンによりパワーウインドやヘッドライトが起動されたりオンされると、これに伴ってモータジェネレータ５に流れるものに近い大きなラッシュ電流がパワーウインドやヘッドライトに瞬時的に流れた後、バッテリ１３から流れる放電電流は、例えば３５Ａ（アンペア）に満たない定常電流に移行する。
【００８６】
話を構成の説明に戻すと、本実施形態の車両用バッテリ充電状態測定装置１は、上述したバッテリ１３の充電状態を測定するもので、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測定する電流センサ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を測定する電圧センサ１７とを備えている。
【００８７】
また、本実施形態の車両用バッテリ充電状態測定装置１は、上述した電流センサ１５及び電圧センサ１７の出力を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変換後に取り込む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。
【００８８】
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が各々接続されており、また、上述した図示しないスタータスイッチ、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、例えばパワーウインドスイッチやライティングスイッチ等が、さらに接続されている。
【００８９】
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が格納されている。
【００９０】
前記ＮＶＭ２５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。
【００９１】
なお、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。
【００９２】
前記ＮＶＭ２７（残存電圧降下差値記憶手段に相当）には、図示しない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により測定されたバッテリ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差値ｅ0 が、格納、記憶される。
【００９３】
なお、上述した電流センサ１５及び電圧センサ１７の出力である電流値及び電圧値は、短い周期で高速にサンプリングされてＩ／Ｆ２１を介して常時マイコン２３のＣＰＵ２３ａに取り込まれ、取り込まれた電流値及び電圧値は前記ＲＡＭ２３ｂのデータエリア（測定電圧・電流記憶手段に相当）に所定期間前のものから最新のものまでの分、格納、記憶される。この記憶されたデータは、電流積算を行ったり、充電状態に応じたバッテリの電圧−電流特性を求めるために利用される。
【００９４】
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１０〜図１２のフローチャートを参照して説明する。
【００９５】
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、初期設定を実行する（ステップＳ１）。
【００９６】
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等を行う。
【００９７】
ステップＳ１の初期設定が済んだならば、次に、ＣＰＵ２３ａは、電流センサ１５の測定したバッテリ１３の放電電流Ｉと電圧センサ１７の測定したバッテリ１３の端子電圧ＶとのＡ／Ｄ変換値を対にしてＩ／Ｆ２１を介して読み込み、読み込んだ実データの最新のものを、所定時間分、ＲＡＭ２３ｂのデータエリアに格納、記憶して収集する実データ収集処理を実行する（ステップＳ２）。このステップＳ２における実データ収集処理は常に継続的に行う。
【００９８】
その後、ステップＳ３及びステップＳ４において後述するフラグＦ１及びＦ２がそれぞれ「１」であるか否かを判定する。フラグＦ１及びＦ２がともに「１」でないとき（ステップＳ３のＮ、ステップＳ４のＮ）には、続いて何れかのスイッチがオフからオンになっているかを判断する（ステップＳ５）。何れかのスイッチがオフからオンしたとき（ステップＳ５のＹ）には、そのスイッチが定負荷であるセルモータに対する放電を開始させるスタータスイッチ（ＳＴＳＷ）であるかどうかを判断する（ステップＳ６）。オフからオンされたスイッチがＳＴＳＷでないとき（ステップＳ６のＮ）には、次に、定負荷であるセルモータと近似した大きなラッシュ電流を流す他の負荷であるパワーウインドモータやヘッドライトに対する放電を開始させるパワーウインドスイッチやライティングスイッチ等の大電流スイッチ（ＬＩＳＷ）がオンされたかどうかを判断する（ステップＳ７）。
【００９９】
オフからオンされたスイッチがＳＴＳＷ及びＬＩＳＷの何れでもないとき（ステップＳ６のＮ、ステップＳ７のＮ）には、これらのスイッチ以外のスイッチがオンされたとして、上述したステップＳ２で収集したバッテリの充電電流及び放電電流を用いて電流積算処理を行う（ステップＳ８）。すなわち、ステップＳ８の電流積算処理では、測定した充電電流のバッテリの現在の充電状態に対する加算と、放電電流のバッテリの現在の充電状態からの減算とをそれぞれ行ってバッテリの充電状態を測定する積算式の充電状態測定を実行する。
【０１００】
ステップＳ８において積算式の充電状態測定を行った後はイグニッションスイッチ（ＩＧＳＷ）及びアクセサリスイッチ（ＡＣＣＳＷ）がオフになっているかどうかを判断し（ステップＳ９）、ＩＧＳＷ及びＡＣＣＳＷがオフになっていなければ（ステップＳ９のＮ）、そのままステップＳ２の実データ収集処理を継続的に行う。これに対し、ＩＧＳＷ及びＡＣＣＳＷがオフになっていれば（ステップＳ９のＹ）、タイマＴをクリアして（ステップＳ１０）からステップＳ２の実データ収集処理を継続的に行う。タイマＴは、後述するように、ＩＧＳＷ及びＡＣＣＳＷがオフしてからの時間を計時するためのもので、充放電によって発生した最大の分極が例えば２４時間の所定時間Ｔｈを経過することによって解消することに着目し、このタイマＴの計時時間ＴがＴｈ以上であるかどうかによって分極の解消を判断するために利用される。
【０１０１】
ＳＴＳＷがオフからオンすると（ステップＳ６のＹ）、次にタイマＴの計時した時間が所定時間Ｔｈ以上であるかどうかを判断し（ステップＳ１１）、タイマＴの計時した時間が所定時間Ｔｈを経過しているとき（ステップＳ１１のＹ）には、ステップＳ２で収集してある実データからＳＴＳＷがオフからオンになる直前のバッテリ端子電圧である開回路電圧ＯＣＶを抽出し、これをＮＶＭ２５に格納、記憶し、この記憶したＯＣＶに基づいて残存容量を演算し、この演算した残存容量を用いて現在の充電状態を更新して設定する充電状態更新設定処理を行う（ステップＳ１２）。すなわち、ステップＳ１２の充電状態更新設定処理では、平衡状態のバッテリによる定負荷であるセルモータへの放電時に、測定した放電の開始前のバッテリの端子電圧である開回路電圧に基づいてバッテリの残存容量を演算して、この演算により求めた残存容量を用いて現在の充電状態を更新して設定する。
【０１０２】
バッテリの残存容量の演算は、具体的には、ステップＳ１２で記憶したＯＣＶを、
ＳＯＣ＝｛（ＯＣＶ−Ｖｅ）／（Ｖｓ−Ｖｅ）｝×１００（％）
又は、

（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。
【０１０３】
その後、平衡状態のバッテリによる定負荷への放電時に、放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少している期間中に、それぞれ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これらの端子電圧と放電電流との相関を示す、放電電流が減少している期間の電圧−電流（Ｖ−Ｉ）特性を表す式を同定するＶ−Ｉ特性決定処理を後述するステップＳ１５において行うために必要な実データが収集されているかどうかを判断し（ステップＳ１３）、必要なデータが収集されていないとき（ステップＳ１３のＮ）には、フラグＦ１を「１」にしてから（ステップＳ１４）、ステップＳ９或いはステップＳ１０を経て上述のステップＳ２に戻る。ステップＳ１４においてフラグＦ１を「１」にした後は、ステップＳ３の判定がＹＥＳになるので、ステップＳ４〜ステップＳ１２の処理を飛ばしてステップＳ１３に進み、ステップＳ１３の判定がＹＥＳになるまで、すなわち、必要な実データが収集されるまで、ステップＳ２、ステップＳ３、ステップＳ１３、ステップＳ１４、ステップＳ９或いはステップＳ１０が繰り返される。
【０１０４】
Ｖ−Ｉ特性を表す式を同定するために必要な実データが収集されているとき（ステップＳ１３のＹ）には、収集されている実データを用いてＶ−Ｉ特性を示す近似式を同定するＶ−Ｉ特性決定処理を行う（ステップＳ１５）。このステップＳ１５のＶ−Ｉ特性決定処理では、具体的には、以下のような処理を行う。
【０１０５】
すなわち、バッテリの放電電流Ｉが３５Ａ（アンペア）まで低下した場合は、それまでの間に収集したバッテリの端子電圧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し、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、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Ｖ−Ｉ特性式Ｖ＝ａＩ＋ｂを割り出す。
【０１０６】
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、上記割り出した電圧−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Ｓ１６）。続いて、ステップＳ１２においてＮＶＭ２５に格納、記憶されているＯＣＶからステップＳ１６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Ｓ１７）、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀をステップＳ１７で求めた残存電圧降下値ｅ₀に更新する（ステップＳ１８）。残存電圧降下値ｅ₀の更新後は、上記ステップＳ１４において「１」にしたフラグＦ１を「０」にし（ステップＳ１９）てから上記ステップＳ９或いはステップＳ１０を経てステップＳ２に戻り、実データの収集を継続する。
【０１０７】
上記ステップＳ７の判定がＹＥＳのとき、すなわち、定負荷であるセルモータと近似したラッシュ電流を流す他の負荷であるパワーウインドモータやヘッドライトに対する放電を開始させるパワーウインドスイッチやライティングスイッチ等のＬＩＳＷがオフからオンされたとき、或いは、ステップＳ１１の判定がＮＯのとき、すなわち、タイマＴの計時した時間が所定時間Ｔｈ以上でなく分極が解消していないときには、ステップＳ２０に進んで、放電電流が減少しているときのＶ−Ｉ特性決定処理を後述するステップＳ２２において行うために必要な実データが収集されているかどうかを判断し（ステップＳ２０）、必要なデータが収集されていないとき（ステップＳ２０のＮ）には、フラグＦ２を「１」にしてから（ステップＳ２１）、上記ステップＳ９或いはステップＳ１０を経てステップＳ２に戻り、実データの収集を継続する。
【０１０８】
ステップＳ２０の判定がＹＥＳのとき、すなわち、ステップＳ２２においてＶ−Ｉ特性決定処理を行うために必要な実データが収集されているときには、放電電流が減少している期間の電圧−電流（Ｖ−Ｉ）特性を表す式を同定するＶ−Ｉ特性決定処理を行う（ステップＳ２２）。上述したステップＳ１６と同様にして、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、上記ステップＳ２２で割り出したＶ−Ｉ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Ｓ２３）。次に、上記ステップＳ２３で取得した推定電圧ＶｎにＮＶＭ２７に格納、記憶されている残存電圧降下差値ｅ0 を加算して推定開回路電圧ＯＣＶ´を求め（ステップＳ２４）、この推定開回路電圧ＯＣＶ′に基づいてバッテリの残存容量を演算して、この演算により求めた残存容量を用いて現在の充電状態を更新して設定する（ステップＳ２５）。
【０１０９】
バッテリの残存容量の演算は、具体的には、ステップＳ２４で求めた推定開回路電圧ＯＣＶ´を、電圧比による算出式、
ＳＯＣ＝｛（ＯＣＶ´−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。
【０１１０】
そして、現在の残存容量の更新後は、上記ステップＳ２１において「１」にしたフラグＦ２を「０」にし（ステップＳ２６）てから上記ステップＳ９或いはステップＳ１０を経てステップＳ２に戻り、実データの収集を継続するとともに、上述した処理を繰り返す。なお、、バッテリ１３からの給電が断たれた場合は、図示しない終了処理を行った後一連の処理を停止する。
【０１１１】
以上の説明からも明らかなように、本実施形態の車両用バッテリ充電状態測定装置１では、電流センサ１５及び電圧センサ１７と図１０中のフローチャートにおけるステップＳ２の処理とが、請求項中の電流測定手段２３ａ−１及び電圧測定手段２３ａ−３を構成し、図１０中のステップＳ８が、請求項中の積算式充電状態測定手段２３ａ−２に対応する処理となっていると共に、図１１中のステップＳ１５及びＳ２２の各々が、請求項中の電圧−電流特性決定手段２３ａ−４に対応する処理となっている。
【０１１２】
また、本実施形態の車両用バッテリ充電状態測定装置１では、図１０中のフローチャートにおけるステップＳ１２が、請求項中の第１の充電状態更新設定手段２３ａ−５に対応する処理となっており、図１２中のステップＳ２５が、請求項中の第２の充電状態更新設定手段２３ａ−７に対応する処理となっている。
【０１１３】
さらに、本実施形態の車両用バッテリ充電状態測定装置１では、ＮＶＭ２７と、図１１中のステップＳ１８とにより、請求項中の残存電圧降下値記憶手段２３ａ−６が構成されている。
【０１１４】
また、本実施形態の車両用バッテリ充電状態測定装置１では、バッテリ１３の放電電流Ｉに関して、２５０Ａ（アンペア）が請求項中の所定値に相当している。
【０１１５】
次に、上述のように構成された本実施形態の車両用バッテリ充電状態測定装置１の動作（作用）について説明する。
【０１１６】
まず、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、平衡状態のバッテリの端子電圧である開回路電圧は測定できないので、ＮＶＭ２５に格納、記憶されている開回路電圧ＯＣＶの更新は勿論のこと、ＮＶＭ２７に格納、記憶されている残存電圧降下値ｅ₀の更新も行われず、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。
【０１１７】
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が所定値例えば２５０Ａ（アンペア）を超え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が通常使用される定常電流値例えば３５Ａ（アンペア）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、充電状態にのみ依存する平衡状態の開回路電圧に相当する推定電圧Ｖｎが推定される。
【０１１８】
そして、ＮＶＭ２７に格納、記憶されている残存電圧降下差値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、現在の充電状態を正確な値に更新して設定し直すために利用される。
【０１１９】
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。
【０１２０】
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。
【０１２１】
なお、セルモータとして機能させるモータジェネレータ５からなる定負荷以外の、放電の開始時に２５０Ａ（アンペア）という所定値を越えて増大した後所定値以下に急激に減少するラッシュ電流が流れる他の負荷、例えば、点灯時にラッシュ電流の流れるヘッドランプであっても、定負荷についての上述の考え方が適用できる。走行用動力源としてのエンジンを補助するためモータジェネレータ５を車両が補助駆動源として使用したとき、駆動時に流れるラッシュ電流が所定値を越えて増大した後所定値以下に急激に減少する場合には、定負荷についての上述の考え方が適用できる。したがって、少なくともヘッドランプの点灯又は駆動モータの駆動時毎にも、現在の充電状態が正確な値に更新されて設定し直されるようになる。
【０１２２】
また、本実施形態の車両用バッテリ充電状態測定装置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開始する前の段階で、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、本実施形態の車両用バッテリ充電状態測定装置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の残存電圧降下差値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差値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差値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】
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、本実施形態の車両用バッテリ充電状態測定装置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。
【０１２７】
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１３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１４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。
【０１２８】
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１５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１３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。
【０１２９】
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、本実施形態の車両用バッテリ充電状態測定装置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を求めるようにしている。
【０１３０】
そして、本実施形態の車両用バッテリ充電状態測定装置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１３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−電流特性から推定される推定電圧Ｖｎが、図１３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。
【０１３１】
なお、本実施形態の車両用バッテリ充電状態測定装置１では、平衡状態又は非平衡状態のバッテリからの定負荷又は他の負荷への放電時に、これに伴いバッテリ１３が所定値例えば２５０Ａ（アンペア）を超えた後通常使用される定常電流値例えば３５Ａ（アンペア）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を、対にして周期的に収集し、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を割り出し、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、充電状態にのみ依存する平衡状態の開回路電圧に相当する推定電圧Ｖｎを推定しているが、バッテリ１３の電圧−電流特性を一次式でなく二次式に近似して割り出した方が、より精度の高い推定電圧を求めることができるようになる。
【０１３２】
【発明の効果】
以上説明したように、請求項１又は６記載の発明によれば、電流積算方式によってバッテリの充電状態を測定するものであって、車両の走行中のように充放電電流の変化する中で、測定した充放電電流を加算及び減算することでバッテリの充電状態を測定でき、しかも、平衡状態のバッテリによる定負荷への放電時毎に、電流積算方式によって求めた充電状態に累積する誤差を解消でき、また、平衡状態のバッテリによる定負荷への放電時に、放電時の初期段階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差値として予め求めておき、この残存電圧降下差値を、非平衡状態のバッテリによる定負荷への放電毎に、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−電流特性を表す式に予め定められた仮想電流値を代入して求めたバッテリの現在の推定電圧に加算して推定の開回路電圧を求め、この推定開回路電圧に基づいてバッテリの残存容量を演算し、この演算により求めた残存容量を用いて現在の充電状態を更新して設定することにより、非平衡状態であっても現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できるので、バッテリの個体差や劣化の進行度合い等によって変化する充電状態を正確に割り出し積算すべき元々のバッテリの充電状態をより正確に測定できるようにして、バッテリの充電状態をより正確に測定できるようにした車両用バッテリ充電状態測定方法及び装置を提供することができる。
【０１３３】
上述した請求項２又は７記載の構成によれば、エンジンの始動時毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる車両用バッテリ充電状態測定方法及び装置を提供することができる。
【０１３４】
上述した請求項３又は８記載の構成によれば、非平衡状態であって、しかも、定負荷に対する放電でなくても、定負荷と同様に放電の初期の段階で放電電流が所定値を越えて増大した後該所定値以下に減少する他の負荷に対する放電毎に、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できるので、充放電電流を長期間にわたって連続的に積算することによる大きな累積誤差の発生を生じ難くして、バッテリの充電状態をより正確に測定できるようにした車両用バッテリ充電状態測定方法及び装置を提供することができる。
【０１３５】
上述した請求項４又は９記載の構成によれば、少なくともヘッドランプの点灯又は駆動モータの駆動時毎にも、現在の充電状態が正確な値に更新されて設定されるようになり、それ以前に電流積算方式によって求めた充電状態に累積していた誤差を解消できる車両用バッテリ充電状態測定方法及び装置を提供することができる。
【０１３６】
上述した請求項５又は１０記載の構成によれば、周期的に測定したバッテリの端子電圧と放電電流とを最新の所定時間分収集して格納、記憶して用い、所定値から減少している間の電圧−電流特性を求ているので、電圧−電流特性を求めるための処理を任意時点で行え、処理速度を上げなくても実施可能な車両用バッテリ充電状態測定方法及び装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の車両用バッテリ充電状態測定装置の基本構成図である。
【図２】本発明の車両用バッテリ充電状態測定方法を適用した本発明の一実施形態に係る車両用バッテリ充電状態測定装置の概略構成を一部ブロックにて示す説明図である。
【図３】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４】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５】図４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６】図４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７】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８】図６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４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９】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。
【図１０】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が行う処理の一部を示すフローチャートである。
【図１１】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が行う処理の他の一部を示すフローチャートである。
【図１２】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が行う処理のさらに他の一部を示すフローチャートである。
【図１３】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１４】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１５】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。
【符号の説明】
５定負荷（セルモータ）
１３バッテリ
２３ａ−１電流測定手段
２３ａ−２積算式充電状態測定手段
２３ａ−３電圧測定手段
２３ａ−４電圧−電流特性決定手段
２３ａ−５第１の充電状態更新設定手段
２３ａ−６残存電圧降下値記憶手段
２３ａ−７第２の充電状態更新設定手段
２３ｂ測定電圧・電流記憶手段（ＲＡＭ）[0001]
BACKGROUND OF THE INVENTION
The present invention is a vehicle battery that is mounted on a vehicle that travels using an engine that uses gasoline, light oil, or the like as a power source, and that measures the state of charge of a battery that supplies power when starting the engine to a cell motor for starting the engine. The present invention relates to a charging state measurement method and apparatus.
[Prior art]
[0002]
A vehicle that runs using an engine as a power source is equipped with an alternator that receives AC power during rotation of the engine, so that the power supplied to the load is generated by the alternator during engine rotation. The one that rectifies the alternating current is mainly used, and is rarely supplied with power from the battery. Rather, when the amount of power supplied to the load is smaller than the amount of power generated by the alternator and there is surplus power, a battery that is not fully charged is charged. Therefore, the battery is normally held in a state close to a fully charged state.
[0003]
However, when the power supply to the load continues without rotating the engine, the power supply to the load is exclusively performed from the battery, so that the dischargeable capacity of the battery is reduced. Such a situation is, for example, the time during which the engine is rotating in an idling stop vehicle that requires frequent rotation of the cell motor in order to stop the engine and restart the engine every stop over a certain time. This can occur when the frequency of starting the engine by the cell motor is high relative to the travel distance.
[0004]
In addition, even when the power supply exceeding the power generation amount of the alternator continues, the shortage is covered by the discharge from the battery, so that the dischargeable capacity of the battery is reduced. Such a situation can occur, for example, when the engine speed does not increase and the power supply to a large load continues for a long time in a state where the amount of power generation is small as in a traffic jam.
[0005]
Since the cell motor is a relatively large load and needs to supply a large current at the start of its operation, the dischargeable capacity of the battery decreases, the terminal voltage of the battery decreases and the maximum discharge current also decreases. After stopping once, the cell motor is rotated and the engine cannot be restarted. Therefore, it is important to determine whether or not the engine can be started not only in the idling stop vehicle but also in a vehicle using an engine as a power source. You need to know the possible capacity.
[0006]
Methods for knowing the state of charge of the battery include a voltage measurement method that measures the battery terminal voltage, an electrolyte specific gravity measurement method that measures the specific gravity of the battery electrolyte, and a current integration that integrates the charge / discharge current of the battery (power integration) ) Method.
[0007]
[Problems to be solved by the invention]
However, in the voltage measurement method, the voltage varies depending on the magnitude of the current, and the terminal voltage is not stable unless the discharge current is stabilized. Therefore, in practice, the terminal voltage correlated with the state of charge of the battery can be obtained by measurement. Cannot be expected. In the electrolyte specific gravity measurement method, there is a certain linear correlation between the electrolyte specific gravity of the battery and the state of charge. Therefore, if the electrolyte specific gravity is measured, it should be possible to grasp the state of charge of the battery. However, in practice, in batteries that are being charged or discharged or just after charging and discharging, the specific gravity of the electrolyte becomes non-uniform due to the chemical reaction that occurs between the electrolyte and the electrode. The liquid specific gravity cannot be measured to accurately grasp the state of charge of the battery.
[0008]
In this respect, the current integration (power integration) method has no problems like the voltage measurement method and the electrolyte specific gravity measurement method described above, and integrates the amount of electricity charged and discharged by the battery. This is the mainstream for determining the state of charge during use of the battery with charge / discharge because it is convenient to determine the capacity of the battery represented by
[0009]
That is, in the current integration method, the in-vehicle battery has an Ah value X in a fully charged state corresponding to the type of the battery, and when the Ah value falls below a predetermined value Y, the battery is further discharged. Since it is known that X should not be charged, X is 100% charged state, Y is 0% charged state, Ah value Z per 1% is obtained in advance as (XY) / 100, and charging current Ij The discharge current Id is measured at a constant time interval, and the current value expressed in% each time the integrated value obtained by adding or subtracting the Ah value obtained by multiplying each measured value by the fixed time t becomes ± Ah value Z or more. The charging state during use of the battery is obtained by setting the charging state x to ± 1.
[0010]
However, in the case of this method, when the charge / discharge current of the battery to be integrated cannot be measured accurately, even if there is a slight error, the error accumulates by continuously integrating over a long period of time, and the obtained battery There is a problem that the state of charge of the battery is far from the current state, and as a result, the state of charge of the battery cannot be accurately grasped.
[0011]
Therefore, for example, when the battery has not been used for at least one day and is in an equilibrium state, the open circuit terminal voltage in that state is measured, and when the state of charge is determined using this measured open circuit terminal voltage The charging state obtained by the integration method is updated with the charging state obtained by the open circuit terminal voltage, and the error accumulated in the value representing the charging state obtained by the integration method is canceled.
[0012]
However, the open circuit terminal voltage of the battery changes depending on the individual difference of the battery, the degree of progress of deterioration, and the like, and the charging state itself obtained using this open circuit terminal voltage becomes unreliable. In addition, when the battery is not in an equilibrium state for a long period of time, i.e., when the battery is not used without charging / discharging, if the period is short, the frequency of canceling the accumulated error is extremely low. Therefore, the battery is placed in a state where only the state of charge including a large cumulative error can be known, and there is also a problem that the current state of charge of the battery is not accurate.
[0013]
Therefore, in view of the above-described present situation, the present invention can accurately determine the charge state of the original battery that should be accurately calculated and integrated with the state of charge that changes depending on the individual difference of the battery, the degree of progress of deterioration, etc. It is an object of the present invention to provide a vehicle battery charge state measurement method capable of more accurately measuring the state of charge of the vehicle, and a vehicle battery charge state measurement device suitable for use in carrying out this method.
[0014]
Therefore, in view of the above-described present situation, the present invention makes it difficult to generate a large cumulative error due to continuous accumulation of charge / discharge current over a long period of time, and allows the battery charge state to be measured more accurately. An object of the present invention is to provide a battery charge state measuring method for a vehicle and a vehicle battery charge state measuring device suitable for use in carrying out this method.
[0015]
[Means for Solving the Problems]
The present invention according to claims 1 to 5, which achieves the above object, relates to a vehicle battery charge state measurement method, and the present invention according to claims 6 to 10 relates to a vehicle battery charge state measurement apparatus. It is about.
[0016]
  The present invention described in claim 1 periodically measures a charging current and a discharging current of a battery that is mounted on and used in a vehicle that runs using an engine as a power source, and the charging that is periodically measured. A vehicle battery charge state measurement method for measuring a battery charge state by adding a current to a current charge state of the battery and subtracting the periodically measured discharge current from the current charge state of the battery. InBased on an expression representing the voltage-current characteristics of the battery in various capacities, a value of a current in which the voltage linearly changes with respect to the capacity is obtained in advance as a virtual current,The terminal voltage of the battery in an equilibrium state is measured as an open circuit voltage, the remaining capacity of the battery is calculated based on the measured open circuit voltage, and the current charge state is calculated using the remaining capacity obtained by the calculation In the period when the discharge current increases beyond a predetermined value and then decreases below the predetermined value at the initial stage when discharging to a constant load by the battery in an equilibrium state, A battery terminal voltage and a discharge current are measured periodically, and a voltage-current characteristic indicating a correlation between the battery terminal voltage and the discharge current measured periodically.Obtained by substituting the virtual current into the expressionThe difference between the value of the estimated voltage of the battery and the value of the open circuit voltage at the time of discharging the constant load is determined by the residual polarization due to the effect of residual polarization at the end of the initial discharge when discharging to the constant load by the battery Voltage dropDifferenceResidual voltage dropDifference valueAs a pre-determined, each time the battery in a non-equilibrium state is discharged to the constant load, it is periodically measured during a period in which the discharge current increases beyond a predetermined value and then decreases below the predetermined value. The voltage-current characteristic is calculated from the terminal voltage and discharge current of the battery.Represents the expressionThe obtained voltage-current characteristics.Obtained by substituting the virtual current into the expressionThe previously determined residual voltage drop to the current estimated voltage value of the batteryDifference valueIs added to obtain an estimated open circuit voltage, and the current state of charge is updated and set using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage. The present invention resides in a vehicle battery charge state measurement method.
[0017]
  According to the invention as defined in claim 1, DThe charging current and discharging current of a battery mounted on a vehicle running with a vehicle as a power source are periodically measured, and the periodically measured charging current is added to the current charging state of the battery and periodically Subtracting the measured discharge current from the current charge state of the battery to measure the charge state of the battery by a current integration method, and the charge / discharge current changes as the vehicle travels. The charge state of the battery can be measured by adding and subtracting the measured charge / discharge current.
[0018]
  And, at the time of discharging to a constant load by the battery in an equilibrium state, the open circuit voltage that is the terminal voltage of the battery before the start of this discharge is measured, the remaining capacity of the battery is calculated based on the measured open circuit voltage, Since the current state of charge is updated and set using the remaining capacity obtained by this calculation, the error accumulated in the state of charge obtained by the current integration method is eliminated each time the battery in the equilibrium state is discharged to a constant load. it can.
[0019]
  Further, when discharging to a constant load by a battery in an equilibrium state, the terminal voltage and discharge current of the battery during the period in which the discharge current increases in excess of a predetermined value and decreases to the predetermined value or less in the initial stage. The voltage-current characteristics indicating the correlation between the battery terminal voltage and the discharge current measured periodically are measured.Calculated by substituting virtual current into the expressionThe difference between the estimated voltage value of the battery and the open circuit voltage value when the battery is discharged at a constant load is expressed as the residual voltage drop due to the effect of the residual polarization at the end of the initial discharge when the battery discharges to the constant load. amountDifferenceResidual voltage dropDifference valueAs previously obtained. This residual voltage dropThe difference value represents the magnitude of the difference when the estimated voltage should be approximately equal to the open circuit voltage just before the start of discharge due to various factors, and the open circuit voltage is estimated from the estimated voltage. In this case, the open circuit voltage can be estimated by correcting the estimated voltage by this difference value.
[0020]
  In addition, for each discharge to a constant load by a battery in an unbalanced state, the battery terminal voltage and discharge measured periodically during a period when the discharge current increases beyond a predetermined value and then decreases below the predetermined value. Voltage-current characteristics from currentRepresents the expressionThe voltage-current characteristicsSubstituting virtual current into the expressionEstimate the current estimated voltage of the battery.
[0021]
  Even if the discharge is from a non-equilibrium state, if the discharge current increases beyond the predetermined value and then decreases below the predetermined value at the initial stage, the voltage drop value due to the polarization component caused by this discharge is Since it becomes equal to the residual voltage drop value generated when discharging to a constant load by the battery in an equilibrium state, the residual voltage drop obtained in advance to the estimated current battery voltage value.Difference valueTo calculate the estimated open circuit voltage, calculate the remaining capacity of the battery based on the estimated open circuit voltage, and update and set the current state of charge using the calculated remaining capacity.
[0022]
Therefore, even in the non-equilibrium state, the current charge state is updated to an accurate value and set every time the discharge current increases beyond a predetermined value at the initial stage of discharge and then decreases below the predetermined value. The error accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0023]
According to a second aspect of the present invention, there is provided the vehicle battery charge state measuring method according to the first aspect, wherein the constant load is a cell motor for starting the engine of the vehicle. It exists in the charge state measuring method.
[0024]
According to the second aspect of the present invention, since the constant load is a cell motor for starting the engine of the vehicle, in addition to the operation of the first aspect of the invention, the current charge state is determined every time the engine is started. Is updated and set to an accurate value, and errors accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0025]
  According to a third aspect of the present invention, in the vehicle battery charge state measuring method according to the first or second aspect, a discharge current is generated at an early stage of discharge in the same manner as the constant load by the battery in an unbalanced state. For each discharge to another load that increases beyond a predetermined value and then decreases below the predetermined value, periodically during a period when the discharge current increases beyond the predetermined value and then decreases below the predetermined value The voltage-current characteristics are determined from the measured terminal voltage and discharge current of the battery.Represents the expressionThe obtained voltage-current characteristics.Obtained by substituting the virtual current value into the expressionThe previously determined residual voltage drop to the current estimated voltage value of the batteryDifference valueIs added to obtain an estimated open circuit voltage, and the current state of charge is updated and set using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage. The present invention resides in a vehicle battery charge state measurement method.
[0026]
  According to the third aspect of the present invention, even when the discharge from the non-equilibrium state is a discharge to a load other than the constant load, the other load is discharged at the initial stage of the discharge in the same manner as the constant load. In the case where the current increases beyond a predetermined value and then decreases below the predetermined value, the voltage drop value due to the polarization component generated by this discharge is the above-mentioned remaining value generated when discharging to a constant load by an equilibrium battery. Since it becomes equal to the voltage drop value, in addition to the operation of the invention according to

claim

1 or 2, the remaining voltage drop obtained in advance to the estimated current battery voltage value.Difference valueTo calculate the estimated open circuit voltage, calculate the remaining capacity of the battery based on the estimated open circuit voltage, and update and set the current state of charge using the calculated remaining capacity.
[0027]
Therefore, even in a non-equilibrium state, and even if the discharge is not to a constant load, the discharge current increases beyond a predetermined value at the initial stage of discharge in the same way as a constant load and then decreases to the predetermined value or less. The current charge state is updated and set to an accurate value every time the load is discharged, and the error accumulated in the charge state obtained by the current integration method before that can be eliminated.
[0028]
According to a fourth aspect of the present invention, there is provided the vehicle battery charge state measuring method according to the third aspect, wherein the other load assists an engine as a headlamp through which a rush current flows when lit and a power source for traveling. Therefore, the vehicle battery charge state measuring method is characterized in that the vehicle has at least one of a drive motor that has a rush current when driven as an auxiliary drive source.
[0029]
According to the present invention as set forth in claim 4, the vehicle has an auxiliary drive source for assisting an engine as a headlamp through which a rush current flows when another load is lit, and a driving power source. Since it is at least one of the flowing drive motors, the current state of charge is updated and set to an accurate value at least every time the headlamp is turned on or the drive motor is driven. The error accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0030]
  According to a fifth aspect of the present invention, in the vehicle battery charge state measuring method according to any one of the first to fourth aspects, the terminal voltage and discharge current of the battery measured periodically are updated to the latest predetermined value. The amount of time collected, stored and stored, and using the battery terminal voltage and discharge current for the latest predetermined time stored, the discharge current exceeds a predetermined value at the initial stage of discharge. The voltage-current characteristics during the period when the voltage increases and then decreases below the predetermined valueRepresents the expressionThe present invention resides in a method for measuring a state of charge of a vehicle battery.
[0031]
  According to the present invention as set forth in claim 5, the terminal voltage and discharge current of the battery measured periodically are collected and stored for the latest predetermined time, and the stored latest predetermined voltage is stored. Using the terminal voltage and discharge current of the battery for the time, the voltage-current characteristics while decreasing from the predetermined valueRepresents the expressionIn addition to the action of the invention according to any one of claims 1 to 4, the voltage-current characteristic isRepresents the expressionProcessing to obtain can be performed at an arbitrary time.
[0032]
  In addition, as shown in the basic configuration diagram of FIG. 1, the present invention described in claim 6 periodically changes the charging current and discharging current of the battery 13 mounted on and used in a vehicle that runs using the engine as a power source. Current measuring means 23a-1 for measuring the current, addition of the charging current periodically measured by the current measuring means to the current charging state of the battery, and the discharge current periodically measured by the current measuring means A voltage for measuring a terminal voltage of the battery in a vehicle battery charge state measuring device including an integrated charge state measurement unit 23a-2 that measures the state of charge of the battery by performing subtraction from the current state of charge of the battery. Terminal voltage of the battery measured periodically by the measuring means 23a-3, the voltage measuring means and the current measuring means, respectively. Voltage showing the correlation between the discharge current these terminal voltage and a discharge current - current characteristicsRepresents the expressionThe terminal voltage of the battery in an equilibrium state is measured as an open circuit voltage by the voltage-current characteristic determining means 23a-4 to be determined and the voltage measuring means, and the remaining capacity of the battery is calculated based on the measured open circuit voltage The first charge state update setting means 23a-5 that updates and sets the current charge state using the remaining capacity obtained by the calculation, and when the battery in the equilibrium state is discharged to the constant load 5 The battery terminals measured periodically by the voltage measuring means and the current measuring means during a period in which the discharge current increases in excess of a predetermined value and then decreases below the predetermined value in the initial stage. The voltage-current characteristics indicating the correlation between the terminal voltage and the discharge current from the voltage and the discharge currentRepresents the expressionThe voltage-current characteristic determining means determines the voltage-current characteristic determined by the voltage-current characteristic determining means.Substituting the value of the current in which the voltage linearly changes with respect to the capacity obtained in advance as a virtual current based on the expression representing the voltage-current characteristics of the battery at various capacities in the expressionThe difference between the value of the estimated voltage of the battery and the value of the open circuit voltage at the time of discharging the constant load is determined by the residual polarization due to the effect of residual polarization at the end of the initial discharge when discharging to the constant load by the battery. Voltage dropDifferenceResidual voltage dropDifference valueRemaining voltage drop to remember asDifference valueFor each discharge to the constant load by the storage means 23a-6 and the battery in an unbalanced state, the voltage measurement is performed during a period in which the discharge current increases beyond a predetermined value and then decreases below the predetermined value. Voltage-current characteristics from the terminal voltage and discharge current of the battery measured periodically by the current measuring means and the current measuring means, respectively.Represents the expressionThe voltage-current characteristic determining means determines the voltage-current characteristic determined by the voltage-current characteristic determining means.Obtained by substituting the virtual current into the expressionThe remaining voltage drop to the current estimated voltage value of the batteryDifference valueResidual voltage drop pre-stored in storage meansDifference valueTo obtain an estimated open circuit voltage, and update and set the current charge state using the remaining battery capacity calculated based on the obtained estimated open circuit voltage. 23a-7, the vehicle battery charge state measuring device.
[0033]
According to the sixth aspect of the present invention, in the vehicle battery charge state measurement device, the current measurement means 23a-1 is mounted on a vehicle that runs using the engine as a power source and the charge current and discharge of the battery 13 used. Each of the currents is periodically measured, and the charging current measuring unit 23a-2 adds the charging current periodically measured by the current measuring unit to the current charging state of the battery and periodically measures the discharging current of the battery. Subtract from the current state of charge to measure the state of charge of the battery, adding and subtracting the measured charge / discharge current while the charge / discharge current changes as the vehicle is running Can measure the state of charge of the battery.
[0034]
Then, the first charge state update setting unit 23a-5 measures the terminal voltage of the battery in an equilibrium state as an open circuit voltage by the voltage measurement unit 23a-3, and based on the measured open circuit voltage, the remaining capacity of the battery Since the current state of charge is updated and set using the remaining capacity obtained by this calculation, every time when the battery in an equilibrium state is discharged to a constant load, the integration type charging state measuring means uses the current integration method. Errors accumulated in the obtained charge state can be eliminated.
[0035]
  Further, when the residual voltage drop value storage means 23a-6 discharges to a constant load by the battery in an equilibrium state, the discharge current increases beyond a predetermined value at the initial stage and then decreases below the predetermined value. These terminal voltages determined by the voltage-current characteristic determining means 23a-4 from the terminal voltage and discharge current of the battery periodically measured by the voltage measuring means 23a-3 and the current measuring means 23a-1 during the period Voltage-current characteristics showing correlation with discharge currentSubstituting the value of the current in which the voltage linearly changes with respect to the capacity obtained in advance as a virtual current based on the expression representing the voltage-current characteristics of the battery at various capacities in the expressionThe difference between the estimated voltage of the battery and the open circuit voltage when the battery is discharged at a constant load with a predetermined large current value is calculated as the effect of residual polarization at the end of the initial discharge when the battery discharges to a constant load. Residual voltage drop due toDifferenceResidual voltage dropDifference valueI remember asThis residual voltage drop difference value represents the difference in magnitude when the estimated voltage should be approximately equal to the open circuit voltage immediately before the start of discharge due to various factors. When the voltage is estimated, the open circuit voltage can be correctly estimated by correcting the estimated voltage with this difference value.
[0036]
  During the period when the second charge state update setting means 23a-7 discharges to a constant load by the battery in the non-equilibrium state, the discharge current increases beyond a predetermined value and then decreases below the predetermined value. The voltage-current characteristics are determined from the battery terminal voltage and the discharge current measured periodically by the voltage measuring means and the current measuring means, respectively.Represents the expressionThe voltage-current characteristic determining unit 23a-4 determines the voltage-current characteristic determined by the voltage-current characteristic determining unit 23a-4.Calculated by substituting virtual current into the expressionTo the current estimated voltage value of the batteryDifference valuePre-stored in storage means 23a-6Difference valueAre added to obtain an estimated open circuit voltage, and the current state of charge is updated and set using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage.
[0037]
  Therefore, every time the battery is discharged to a constant load even in the non-equilibrium state, the second charge state update setting means 23a-5Based on the estimated open circuit voltage corrected for the difference between the estimated voltage and the open circuit voltage caused by various factors,The current state of charge is updated and set to an accurate value, and errors accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0038]
The present invention described in claim 7 resides in the vehicle battery charge state measurement device according to claim 6, wherein the constant load is a cell motor of the vehicle. .
[0039]
According to the present invention described in claim 7, since the constant load is the cell motor 5 of the preceding vehicle, in addition to the operation of the invention according to claim 6, the current state of charge is an accurate value every time the engine is started. The error accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0040]
  Further, the present invention described in claim 8 is the vehicle battery charge state measuring device according to claim 6, wherein the second charge state update setting means is similar to the constant load by the battery in an unbalanced state. At each initial stage of discharge, the discharge current increases beyond a predetermined value and then decreases to the predetermined value or less. For each discharge to another load, the discharge current increases beyond the predetermined value and then decreases to the predetermined value or less. The voltage-current characteristics are obtained from the terminal voltage and discharge current of the battery periodically measured by the voltage measuring means and the current measuring means duringRepresents the expressionThe voltage-current characteristic determining means determines the voltage-current characteristic determined by the voltage-current characteristic determining means.Obtained by substituting the virtual current value into the expressionThe remaining voltage drop to the current estimated voltage value of the batteryDifference valueResidual voltage drop pre-stored in storage meansDifference valueTo obtain an estimated open circuit voltage, and update and set the current state of charge using the remaining battery capacity calculated based on the obtained estimated open circuit voltage. It exists in a state-of-charge measuring device.
[0041]
  According to the present invention as set forth in claim 8, the second charge state update setting means 23a-7 allows the discharge current to exceed a predetermined value at the initial stage of discharge as in the case of the constant load by the battery in the non-equilibrium state. During discharge to another load that increases and decreases to the predetermined value or less, during a period in which the discharge current increases beyond the predetermined value and then decreases to the predetermined value or less, the voltage measuring unit and the current measuring unit Voltage-current characteristics are determined from the battery terminal voltage and discharge current measured periodically.Represents the expressionThe voltage-current characteristic determining unit 23a-4 determines the voltage-current characteristic determined by the voltage-current characteristic determining unit 23a-4.Calculated by substituting the virtual current value into the expressionThe remaining voltage drop to the current estimated voltage value of the batteryDifference valueResidual voltage drop prestored in storage means 23a-6Difference valueAre added to obtain an estimated open circuit voltage, and the current state of charge is updated and set using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage.
[0042]
Therefore, even in a non-equilibrium state, and even if the discharge is not to a constant load, the discharge current increases beyond a predetermined value at the initial stage of discharge in the same way as a constant load and then decreases to the predetermined value or less. Each time the battery is discharged to the load, the second charge state update setting unit 23a-5 updates and sets the current charge state to an accurate value, and the charge previously obtained by the current integration method is set. The error accumulated in the state can be eliminated.
[0043]
According to a ninth aspect of the present invention, in the vehicular battery charge state measuring device according to the eighth aspect, the other load assists an engine as a headlamp through which a rush current flows when the lamp is lit, and a driving power source. Therefore, the vehicle battery charge state measuring device is characterized in that it is at least one of a drive motor that the vehicle has as an auxiliary drive source and through which a rush current flows.
[0044]
According to the present invention as set forth in claim 9, the vehicle has an auxiliary drive source for assisting an engine as a headlamp through which a rush current flows when a constant load is lit, and a driving power source. Since it is at least one of the drive motors, the current state of charge is updated and set to an accurate value at least every time the headlamp is turned on or the drive motor is driven. The error accumulated in the state of charge obtained by the current integration method before that can be eliminated.
[0045]
  According to a tenth aspect of the present invention, in the vehicle battery charge state measuring device according to any one of the sixth to ninth aspects, the terminal voltage and the discharge current of the battery measured periodically are the latest predetermined. A measurement voltage / current storage unit 23b that collects, stores, and stores data for a time is provided, and the voltage-current characteristic determination unit stores the battery for the latest predetermined time stored in the measurement voltage / current storage unit. Using the terminal voltage and discharge current, the voltage-current characteristics areRepresents the expressionIt exists in the vehicle battery charge condition measuring apparatus characterized by calculating | requiring.
[0046]
  According to the present invention as set forth in claim 10, the measured voltage / current storage means 23b collects, stores and stores the terminal voltage and discharge current of the battery measured periodically for the latest predetermined time. The current characteristic determining means 23a-4 calculates the voltage-current characteristic using the battery terminal voltage and discharge current for the latest predetermined time stored in the measured voltage / current storage means.Represents the expressionTherefore, in addition to the effects of the inventions of claims 6 to 9, the voltage-current characteristics while the discharge current is decreasing from the predetermined value are obtained.Represents the expressionProcessing for obtaining the voltage-current characteristic determining means can be performed at an arbitrary time.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the vehicle battery charge state measurement method according to the present invention will be described with reference to FIG. 2 together with the vehicle battery charge state measurement apparatus according to the present invention. Before that, the characteristics of the battery itself will be examined.
[0048]
First, focusing on the fact that the battery terminal voltage represents the state of the battery including various conditions of the battery, the charging capacity that changes depending on the individual difference of the battery, the degree of progress of deterioration, etc. is accurately calculated and integrated. In order to be able to measure the state of charge of the original battery to be more accurately, a method for enabling a stable voltage to be estimated from the terminal voltage of the battery that changes drastically while the vehicle is running will be described in detail below. .
[0049]
By the way, as shown in the characteristic diagram of FIG. 3, when the battery is discharged at a constant current of 10 to 80 (A) every 10 A, the discharge time (horizontal axis) and the battery terminal voltage (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.
[0050]
In the characteristic diagram of FIG. 3, the horizontal axis 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 should be regarded as the battery capacity. Can do.
[0051]
Therefore, when the characteristic diagram of FIG. 3 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, a larger electric power can be taken out as the discharge current is smaller, 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.
[0052]
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.
[0053]
Therefore, attention is paid to the relationship between the electrolyte specific gravity and open circuit voltage of the battery having a substantially linear correlation, and the relationship between the electrolyte specific gravity and the state of charge of 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, which should have a good correlation.
[0054]
However, the only weakness of this capacity calculation method is that the open circuit voltage of the battery can be measured only when there is no change in the charge state except for the spontaneous discharge, in other words, it changes to the charge state. When the battery is discharged, that is, when the battery is used, the open circuit voltage of the battery cannot be measured.
[0055]
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.
[0056]
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. 4, even if the charge state of the battery does not change, the battery terminal voltage decreases if the discharge current increases. Therefore, there is a voltage-current characteristic (IV characteristic) showing a negative correlation between the terminal voltage and the discharge current, and this voltage-current characteristic changes the state of charge of the battery. It turns out that it changes.
[0057]
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.
[0058]
First, a certain current I_aAnd this current I_aLower current I_bThe battery is continuously discharged by a pulsed current that alternately appears periodically, and a set of battery terminal voltage and discharge current (I_a, V₁), (I_b, V₂), (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.
[0059]
Then, a set of battery terminal voltage and discharge current (I_a, V₀₁), (I_b, V₀₂), (I_a, V₀₃), (I_b, V₀₄),... By the least square method, V = a₁I + b₁The coefficient a in the linear voltage-current characteristic equation of the battery₁, B₁To obtain this equation V = a₁I + b₁Is defined as the voltage-current characteristic of the battery corresponding to the capacity during the above sampling.
[0060]
Next, a pulsed current I is generated by the same discharge as described above._a, I_aThe battery terminal voltage and the discharge current (I) appearing in the opposite phase to the discharge current at that time._a, V₁₁), (I_b, V₁₂), (I_a, V₁₃), (I_b, V₁₄),... Are continuously sampled, and from these, V = a by the least square method.₂I + b₂The coefficient a in the linear voltage-current characteristic equation of the battery₂, B₂To obtain this equation V = a₂I + b₂Is defined as the voltage-current characteristic of the battery corresponding to the capacity during the above sampling.
[0061]
Thereafter, in the same manner, V = a_nI + b_nCoefficient a in the linear voltage-current characteristic equation of the battery_n, B_nTo obtain this equation V = a_nI + b_nIs 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%.
[0062]
It should be noted that a predetermined set of battery terminal voltages and discharge currents (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 to these_nI + b_nThe relationship between and is schematically shown in FIG.
[0063]
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. 5 is obtained.
[0064]
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, since Vn becomes a non-linear characteristic in which the voltage sharply decreases.
[0065]
However, according to the graph of FIG. 5, 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. 6, in the case of the illustrated graph, the characteristic change of the estimated voltage Vn in the region near the capacitance 0 is inflected at the virtual current value Is = −10A. As a matter of course, in a battery having characteristics different from the illustrated characteristics, the value of the virtual current value Is is a value other than −10 A.
[0066]
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.
[0067]
Therefore, the voltage-current characteristics of the battery corresponding to each capacity obtained as described above are shown in the graph of FIG. 7 where the vertical axis is the discharge current I and the horizontal axis is the terminal voltage V. Let us verify that Vn exhibits a linear characteristic with respect to the battery capacity.
[0068]
First, a coefficient a representing the slope of each voltage-current characteristic equation₁, A₂, ..., a_nAre different from each other, and the coefficient b representing the intercept of each voltage-current characteristic equation₁, B₂, ..., b_nTherefore, in the positive discharge current region that actually exists in FIG. 7, there is no discharge current value I in which the terminal voltage V changes linearly with respect to the change in battery capacity.
[0069]
However, in the negative discharge current region, which is an imaginary region in FIG. 7, when the discharge current value I = −10 A, the terminal voltage V exhibits a characteristic that changes linearly with respect to the battery capacity. 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.
[0070]
Therefore, when the relationship between the capacity of the battery at the virtual current value Is = −10 A and the estimated voltage Vn having a linear correlation with this 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).
[0071]
  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. And its characteristic formula (V = aI + b)Sought in advanceBy substituting the virtual current value Is = −10 A and obtaining the estimated voltage Vn, the state of charge SOC of the battery can be obtained from the estimated voltage Vn.
[0072]
Then, by converting the ratio of the estimated voltage Vn on the vertical axis of FIG. 8 to the open circuit voltage Vs at the time of full charge, and obtaining the current state of charge SOC for the full charge capacity,
SOC = {(Vn−Ve) / (Vs−Ve)} × 100 (%)
It becomes.
[0073]
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.
[0074]
By the way, during the battery discharge, as shown in FIG. 9, a voltage drop due to the influence of the pure resistance (battery ohmic resistance), that is, an IR drop obtained by multiplying the pure resistance by the discharge current, or a voltage drop caused by the 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.
[0075]
In particular, as shown in FIG. 9, the activation polarization for advancing the oxidation-reduction 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.
[0076]
  Therefore, as described above, in order to determine the state of charge SOC of the battery, instead of the open circuit voltage of the battery that cannot be measured during dischargeUsing a predetermined virtual currentWhen the estimated voltage Vn is obtained, when the terminal voltage and the discharge current are measured during discharging to obtain the voltage-current characteristics of the battery, the terminal voltage includes a voltage drop due to polarization during discharge. Therefore, the obtained voltage-current characteristic of the battery and the estimated voltage Vn estimated from the voltage-current characteristic are not only the battery charge state SOC but also the voltage drop due to polarization.Size ofTherefore, if the estimated voltage Vn is used as it is, the state of charge SOC of the battery cannot be obtained accurately.
[0077]
  In addition,The state of charge of the battery is determined using an estimated voltage, which is an estimated terminal voltage in a constant load discharge state of the battery, obtained from the correlation between the terminal voltage of the battery and the discharge current that can be measured at the time of discharging. At this time, even when the terminal voltage of the battery being discharged used to obtain the estimated voltage is not completely eliminated by the voltage increase or voltage drop due to the previous charge or discharge,By obtaining an estimated voltage that eliminates the effect of the difference in voltage drop due to polarization,If the state of charge of the battery can be accurately measured, at this point, the measured state of charge of the battery is used instead of the state of charge of the battery that has been obtained by the integration method so far. Accumulation can be performed so that large errors do not accumulate, and the charge capacity that changes depending on the individual difference of the battery, the degree of progress of deterioration, and the like can be accurately determined, so that the state of charge of the battery can be measured more accurately. Therefore, a specific embodiment of a vehicle battery charge state measuring method and apparatus that enables such a case will be described below with reference to FIG.
[0078]
FIG. 2 is an explanatory diagram partially showing in block form a schematic configuration of a vehicle battery charge state measuring apparatus according to an embodiment of the present invention to which the vehicle battery charge state measuring method of the present invention is applied. The vehicle battery state-of-charge measuring device of this embodiment shown by is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3.
[0079]
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.
[0080]
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.
[0081]
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. A large current is passed through. This current is called a rush current. At this time, the motor generator 5 consumes more power alone than in the steady state in which a plurality of other electric loads mounted on the hybrid vehicle are operating simultaneously.
[0082]
Incidentally, in the hybrid vehicle of the present embodiment, although the starter switch is off, an accessory switch and an ignition switch (not shown), and switches (not shown) for electrical components (loads) other than the motor generator 5 are on. Therefore, when an air conditioner, an audio device, a power window, a headlight, a room lamp (none of which are shown), etc. are operating steadily, the discharge current flowing from the battery 13 has a plurality of electric components at the same time. Even if it is operating, for example, it is less than 35 A (ampere).
[0083]
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 to start the engine 3, no other electrical components are operating. However, for example, a rush current reaching 250 A (ampere) flows instantaneously from the battery 9. The same thing is not the same as the motor generator 5 used as a cell motor even when the power window or headlight, which is a relatively large load, is activated or turned on by turning on the power window switch or lighting switch. A large rush current close to that flowing in the generator 5 flows instantaneously.
[0084]
Therefore, in the vehicle battery charge state measuring apparatus 1 of the present embodiment, whether 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) is determined by the motor. This is a guideline for distinguishing that constant load discharge for operating the generator 5 as a cell motor is being performed and that load discharge similar to this constant load discharge is being performed.
[0085]
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 an ignition key (not shown). Transition. In addition, when the ignition switch or the accessory switch is on, if the power window or the headlight is activated or turned on by turning on the power window switch or the lighting switch, a large rush current close to that flowing to the motor generator 5 is associated with this. Is instantaneously flowing to the power window or the headlight, the discharge current flowing from the battery 13 shifts to a steady current that is less than 35 A (ampere), for example.
[0086]
Returning to the description of the configuration, the vehicle battery state-of-charge measuring device 1 of the present embodiment measures the state of charge of the battery 13 described above. The motor generator 5 functions as a motor for assist travel, a cell motor, and the like. , A current sensor 15 for measuring the discharge current I of the battery 13 with respect to the electrical components, 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 a voltage sensor 17 for measuring the terminal voltage V.
[0087]
Further, in the vehicle battery charge state measuring apparatus 1 of the present embodiment, the outputs of the current sensor 15 and the voltage sensor 17 described above are A / D converted in an interface circuit (hereinafter abbreviated as “I / F”) 21. A microcomputer (hereinafter abbreviated as “microcomputer”) 23 to be taken in, and nonvolatile memories (hereinafter abbreviated as “NVM”) 25 and 27 connected to the microcomputer 23 are further provided.
[0088]
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 NVM 25 in addition to the RAM 23b and the ROM 23c. An unillustrated starter switch, ignition switch, accessory switch, and switches of electrical components (loads) other than the motor generator 5 such as a power window switch and a lighting switch are further connected.
[0089]
The RAM 23b has a data area for storing various data and a work area used for various processing operations, and the ROM 23c stores a control program for causing the CPU 23a to perform various processing operations.
[0090]
The NVM 25 has a terminal voltage V in an equilibrium state of the battery 13 that changes in accordance with a change in charge capacity, that is, a state in which voltage rise or voltage drop due to polarization during charge / discharge is completely eliminated and remains. Stored and stored as an open circuit voltage OCV of the battery 13.
[0091]
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.
[0092]
  NVM27 (residual voltage dropDifference value(Corresponding to the storage means), when an unillustrated ignition switch is turned on, when the battery 13 instantaneously performs a constant load discharge in order to start the engine 3 by the motor generator 5, Based on the correlation between the terminal voltage V of the battery 13 measured by the current sensor 15 and the voltage sensor 17 and the discharge current I, this is an estimated terminal voltage V in a constant load discharge state, which is estimated by a process described later. The estimated voltage Vn is subtracted from the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25, and the residual voltage drop that is the residual voltage drop due to the effect of the residual polarization at the end of the discharge of the battery 13.Difference valuee0 is stored and stored.
[0093]
The current values and voltage values that are the outputs of the current sensor 15 and the voltage sensor 17 described above are sampled at a high speed in a short cycle, and are always taken into the CPU 23a of the microcomputer 23 via the I / F 21. The voltage value is stored and stored in the data area (corresponding to the measured voltage / current storage means) of the RAM 23b from the previous one to the latest one. This stored data is used to perform current integration or to obtain a voltage-current characteristic of the battery according to the state of charge.
[0094]
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.
[0095]
When the microcomputer 23 is activated to receive power from the battery 13 and the program is started, the CPU 23a first performs initial setting (step S1).
[0096]
In the initial setting in step S1, the flag in the flag area provided in the work area of the RAM 23b is reset, the timer area is reset to zero, and the like.
[0097]
When the initial setting in step S1 is completed, the CPU 23a then calculates an A / D conversion value between the discharge current I of the battery 13 measured by the current sensor 15 and the terminal voltage V of the battery 13 measured by the voltage sensor 17. A real data collection process is executed in which the latest actual data read is stored in the data area of the RAM 23b for a predetermined time, and is stored and collected via the I / F 21 (step S2). The actual data collection process in step S2 is always performed continuously.
[0098]
Thereafter, in steps S3 and S4, it is determined whether flags F1 and F2, which will be described later, are “1”, respectively. When both the flags F1 and F2 are not “1” (N in step S3, N in step S4), it is subsequently determined whether any of the switches is turned on from off (step S5). When any of the switches is turned on from OFF (Y in Step S5), it is determined whether or not the switch is a starter switch (STSW) that starts discharge to the cell motor that is a constant load (Step S6). When the switch turned off to STSW is not STSW (N in step S6), next, the discharge to the power window motor and headlights, which are other loads that flow a large rush current approximating that of the constant load cell motor, is started. It is determined whether a large current switch (LISW) such as a power window switch or a lighting switch to be turned on is turned on (step S7).
[0099]
When the switch turned on from OFF is neither STSW nor LISW (N in Step S6, N in Step S7), it is assumed that switches other than these switches are turned on, and the battery collected in Step S2 described above is Current integration processing is performed using the charging current and discharging current (step S8). That is, in the current integration process in step S8, the integration in which the charge state of the battery is measured by adding the measured charge current to the current charge state of the battery and subtracting the discharge current from the current charge state of the battery, respectively. Perform the state of charge measurement of the expression.
[0100]
After performing the integrated charging state measurement in step S8, it is determined whether the ignition switch (IGSW) and the accessory switch (ACCSW) are turned off (step S9), and if IGSW and ACCSW are not turned off. (N in step S9), the actual data collection process in step S2 is continuously performed as it is. On the other hand, if IGSW and ACCSW are off (Y in step S9), the timer T is cleared (step S10) and the actual data collection process in step S2 is continuously performed. As will be described later, the timer T is for measuring the time after the IGSW and ACCSW are turned off, and the maximum polarization generated by charging / discharging is eliminated when a predetermined time Th of 24 hours elapses, for example. Paying attention to this, it is used to determine whether or not the polarization is eliminated depending on whether the time T of the timer T is equal to or greater than Th.
[0101]
When the STSW is turned on from OFF (Y in step S6), it is then determined whether or not the time measured by the timer T is equal to or longer than the predetermined time Th (step S11), and the time measured by the timer T has passed the predetermined time Th. When the operation is being performed (Y in step S11), the open circuit voltage OCV, which is the battery terminal voltage immediately before the STSW is turned on from the off-state, is extracted from the actual data collected in step S2 and stored in the NVM 25. Then, a remaining capacity is calculated based on the stored OCV, and a charging state update setting process is performed to update and set the current charging state using the calculated remaining capacity (step S12). That is, in the charge state update setting process in step S12, the remaining capacity of the battery is determined based on the measured open circuit voltage, which is the terminal voltage of the battery before the start of discharge, when discharging to the cell motor that is a constant load by the battery in the equilibrium state. And the current state of charge is updated and set using the remaining capacity obtained by this calculation.
[0102]
Specifically, the calculation of the remaining capacity of the battery is performed by using the OCV stored in step S12.
SOC = {(OCV−Ve) / (Vs−Ve)} × 100 (%)
Or

(However, 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.
[0103]
  Thereafter, during discharge to a constant load by the battery in an equilibrium state, the discharge current was periodically measured during the period when the discharge current increased beyond a predetermined value and decreased below the predetermined value at the initial stage of discharge. The voltage-current (V-I) characteristics during the period when the discharge current is decreasing, showing the correlation between the terminal voltage and discharge current of the battery and the correlation between these terminal voltage and discharge current.Represents the expressionIt is determined whether or not actual data necessary for performing the VI characteristic determination process to be identified in step S15 described later is collected (step S13), and when necessary data is not collected (N in step S13). First, after setting the flag F1 to “1” (step S14), the process returns to the above-described step S2 through step S9 or step S10. After the flag F1 is set to “1” in step S14, the determination in step S3 is YES. Therefore, the processing in steps S4 to S12 is skipped and the process proceeds to step S13, that is, until the determination in step S13 is YES, that is, Until the necessary actual data is collected, step S2, step S3, step S13, step S14, step S9 or step S10 is repeated.
[0104]
  VI characteristicsRepresents the expressionWhen actual data necessary for identification is collected (Y in step S13), a VI characteristic determination process for identifying an approximate expression indicating the VI characteristic using the collected actual data is performed. This is performed (step S15). Specifically, in the VI characteristic determination process in step S15, the following process is performed.
[0105]
That is, when the discharge current I of the battery drops to 35 A (ampere), the A / D conversion value between the battery terminal voltage V and the discharge current I collected so far is used to correlate the data. The correlation coefficient r is calculated to check whether the value is within the allowable range of −0.9 ≧ r ≧ −1.0, and the correlation coefficient r is within the allowable range. If the correlation is OK, the least square method is applied to the pair of A / D conversion values 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. Then, the linear VI characteristic equation V = aI + b is determined.
[0106]
Next, a virtual current value Is = −10 A (ampere) at which the estimated voltage Vn in the constant current discharge shows a linear characteristic with respect to the capacity of the battery 13 is calculated as the voltage-current characteristic equation V = aI + b. And the estimated voltage Vn is estimated (step S16). Subsequently, in step S12, the estimated voltage Vn estimated in step S16 is subtracted from the OCV stored and stored in the NVM 25 to obtain a residual voltage drop value e.₀(Step S17) and the remaining voltage drop value e stored and stored in the NVM 27₀Is the residual voltage drop value e obtained in step S17.₀(Step S18). Residual voltage drop value e₀After the update, the flag F1 that was set to “1” in step S14 is set to “0” (step S19), and then the process returns to step S2 through step S9 or step S10 to continue collecting actual data.
[0107]
When the determination in step S7 is YES, that is, a LISW such as a power window switch or a lighting switch that starts discharge to a power window motor or headlight that is another load that passes a rush current approximate to a cell motor that is a constant load. When turned on from OFF or when the determination in step S11 is NO, that is, when the time counted by the timer T is not equal to or longer than the predetermined time Th and the polarization is not eliminated, the process proceeds to step S20, and the discharge current is increased. It is determined whether or not actual data necessary for performing the VI characteristic determination processing when it is decreasing is performed in step S22 described later (step S20), and when necessary data is not collected (step S20). After N in S20, the flag F2 is set to “1” (step S21). Returning to step S2 through the step S9 or step S10, and continues the collection of actual data.
[0108]
  When the determination in step S20 is YES, that is, when actual data necessary for performing the VI characteristic determination process is collected in step S22, the voltage-current (V- I) CharacteristicRepresents the expressionThe VI characteristic determination process to identify is performed (step S22). Similar to step S16 described above, the virtual current value Is = −10 A (ampere) at which the estimated voltage Vn in constant current discharge shows a linear characteristic with respect to the capacity of the battery 13 is determined in step S22. The estimated voltage Vn is estimated by substituting it into the VI characteristic equation V = aI + b (step S23). Next, the remaining voltage drop stored and stored in the NVM 27 in the estimated voltage Vn acquired in step S23.Difference valueThe estimated open circuit voltage OCV 'is obtained by adding e0 (step S24), the remaining capacity of the battery is calculated based on the estimated open circuit voltage OCV', and the current charge is calculated using the remaining capacity obtained by this calculation. The state is updated and set (step S25).
[0109]
Specifically, the calculation of the remaining capacity of the battery is performed by calculating the estimated open circuit voltage OCV ′ obtained in step S24 using a voltage ratio,
SOC = {(OCV′−Ve) / (Vs−Ve)} × 100 (%)
Or a calculation formula by power ratio,

(However, 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.
[0110]
After the current remaining capacity is updated, the flag F2 that was set to “1” in step S21 is set to “0” (step S26), and then the process returns to step S2 through step S9 or step S10. And the above-described processing is repeated. In addition, when the power supply from the battery 13 is cut off, a series of processes is stopped after an unillustrated end process is performed.
[0111]
  As is clear from the above description, in the vehicle battery charge state measuring apparatus 1 of the present embodiment, the current sensor 15 and the voltage sensor 17 are shown in FIG.No fuThe process of step S2 in the chart constitutes the current measuring means 23a-1 and voltage measuring means 23a-3 in the claims, and step S8 in FIG. 10 is the integrated charge state measuring means 23a in the claims. −2 and each of steps S15 and S22 in FIG. 11 corresponds to the voltage-current characteristic determining means 23a-4 in the claims.
[0112]
Further, in the vehicle battery charge state measuring apparatus 1 of the present embodiment, step S12 in the flowchart in FIG. 10 is a process corresponding to the first charge state update setting means 23a-5 in the claims, Step S25 in FIG. 12 is processing corresponding to the second charging state update setting means 23a-7 in the claims.
[0113]
Furthermore, in the vehicle battery state-of-charge measuring device 1 of the present embodiment, the remaining voltage drop value storage means 23a-6 in the claims is configured by the NVM 27 and step S18 in FIG.
[0114]
In the vehicle battery charge state measuring apparatus 1 of the present embodiment, 250 A (ampere) corresponds to the predetermined value in the claims with respect to the discharge current I of the battery 13.
[0115]
Next, the operation (action) of the vehicle battery charge state measuring apparatus 1 of the present embodiment configured as described above will be described.
[0116]
First, in a state where the motor generator 5 operates so as to function as a generator and the battery 13 is being charged accordingly, the open circuit voltage, which is the terminal voltage of the battery in the equilibrium state, cannot be measured, and is stored in the NVM 25. In addition to updating the stored open circuit voltage OCV, the remaining voltage drop value e stored and stored in the NVM 27₀Also, the estimated voltage Vn is not estimated and the state of charge SOC is calculated and updated using the estimated voltage Vn.
[0117]
Next, when the starter switch is turned on, the motor generator 5 of the hybrid vehicle operates so as to function as a cell motor, and when the battery 13 discharges at a constant load exceeding a predetermined value, for example, 250 A (ampere), The discharge current I and the terminal voltage V of the battery 13 detected by the current sensor 15 and the voltage sensor 17 until the discharge current I of the battery 13 in the discharge is reduced to a normally used steady current value, for example, 35 A (ampere). If the data are periodically collected as a pair 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 obtained. The virtual current value Is that is determined and the estimated voltage Vn in the constant current discharge exhibits a linear characteristic with respect to the capacity of the battery 13. -10A and (amperes), the voltage - by substituting the current characteristic equation V = aI + b, the estimated voltage Vn which corresponds to the open circuit voltage of the equilibrium state that depends only on the state of charge is estimated.
[0118]
  And the remaining voltage drop stored and stored in the NVM 27Difference valueBy adding e0 to the previously estimated voltage Vn, a corrected estimated voltage Vn ′ is obtained, 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 used to update and set the current state of charge to an accurate value.
[0119]
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.
[0120]
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 amount₀Is added to the estimated voltage Vn thus estimated, the actual state of charge SOC of the battery 13 can be accurately calculated.
[0121]
In addition to a constant load consisting of a motor generator 5 that functions as a cell motor, other loads in which a rush current that increases after exceeding a predetermined value of 250 A (ampere) at the start of discharge and rapidly decreases to a predetermined value or less flows. Even in a headlamp in which a rush current flows when the lamp is lit, the above-described concept of constant load can be applied. When the motor generator 5 is used as an auxiliary drive source for assisting the engine as a driving power source, the rush current that flows during driving increases beyond a predetermined value and then rapidly decreases below a predetermined value. The above-described concept of constant load can be applied. Therefore, at least every time the headlamp is turned on or the drive motor is driven, the current state of charge is updated to an accurate value and set again.
[0122]
Further, in the vehicle battery state-of-charge measuring device 1 according to the present embodiment, the battery 13 starts from the maximum polarization occurrence state at the stage before the battery 13 starts constant load discharge exceeding 250 A (ampere) with the starter switch being turned on. If the battery 13 has not been charged / discharged for a predetermined time Th necessary for eliminating the polarization, the voltage fluctuation (voltage rise or voltage drop) due to the polarization generated when the battery 13 was previously charged / discharged is completely completed. Therefore, 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 vehicle battery charge state measuring apparatus 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 where the battery 13 is in an equilibrium state, it is stored and stored in the NVM 27. Battery 13 remaining voltage dropDifference valuee0 is the latest residual voltage drop 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.Difference valueUpdated to e0.
[0125]
  For this reason, even if the remaining voltage drop value e0 fluctuates as the state of the battery 13 changes, the remaining voltage drop stored and stored in the NVM 27 each time the battery 13 is in an equilibrium state.Difference valueThe calculation accuracy of the state of charge SOC of the battery 13 can be maintained high by updating e0 to the latest value.
[0126]
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 vehicle battery charge state measuring apparatus 1 of the embodiment, the discharge current I decreases from 250 A (ampere) to 35 A (ampere). It may not be limited to.
[0127]
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 is accompanied by a decrease in 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 decreases than when the discharge current I increases.
[0128]
In addition, 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.
[0129]
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. In consideration of the difference depending on whether or not the battery is in an equilibrium state, as in the vehicle battery charge state measuring device 1 of the present embodiment, the battery 13 collected periodically only while the discharge current I is decreasing. The voltage-current characteristic formula V = aI + b of the battery 13 is obtained using only the discharge current I and the terminal voltage V.
[0130]
In the vehicle battery charge state measuring apparatus 1 of the present embodiment, the open circuit voltage OCV of the battery 13 stored and stored in the NVM 25 is the voltage-current characteristic line during the increase of the discharge current I in FIG. , A point on the discharge current I = 0 A (ampere) is indicated, and 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) are shown. The estimated voltage Vn estimated from the voltage-current characteristic of the battery 13 obtained by using the voltage-current characteristic line during the decrease of the discharge current I in FIG. 13 is on the virtual current value Is = −10 A (ampere). Will be shown.
[0131]
In the vehicle battery charge state measuring apparatus 1 of the present embodiment, when discharging from a balanced or non-equilibrium battery to a constant load or another load, the battery 13 has a predetermined value, for example, 250 A (ampere). The discharge current I of the battery 13 and the terminal voltage V detected by the current sensor 15 and the voltage sensor 17 are paired with a period of time until the steady current value, for example, 35 A (ampere) drops after being exceeded. If the data are collected and satisfy a certain correlation, the least square method is applied to them to determine the linear voltage-current characteristic equation V = aI + b of the battery 13 and the estimated voltage in discharge A virtual current value Is = −10 A (ampere) in which Vn shows a linear characteristic with respect to the capacity of the battery 13 is replaced with this voltage-current characteristic expression V = aI + b. Thus, the estimated voltage Vn corresponding to the open circuit voltage in an equilibrium state that depends only on the state of charge is estimated. However, the voltage-current characteristics of the battery 13 are approximated to a secondary expression instead of a primary expression. This makes it possible to obtain a more accurate estimated voltage.
[0132]
【The invention's effect】
  As described above, according to the first or sixth aspect of the invention, the state of charge of the battery is measured by the current integration method, and the charge / discharge current changes as the vehicle travels. By adding and subtracting the measured charge / discharge current, the state of charge of the battery can be measured, and errors accumulated in the state of charge determined by the current integration method are eliminated each time the battery in equilibrium is discharged to a constant load. In addition, when a battery in an equilibrium state is discharged to a constant load, a residual voltage drop that is a residual voltage drop due to the effect of residual polarization at the end of the initial stage of dischargeDifference valueThis residual voltage drop is determined in advance asDifference valueFor each discharge of a non-equilibrium battery to a constant load, the voltage-current characteristics obtained from the measured battery terminal voltage and discharge current areCalculated by substituting a predetermined virtual current value into the expressionAdd the current estimated voltage of the battery to obtain the estimated open circuit voltage, calculate the remaining battery capacity based on this estimated open circuit voltage, and update the current state of charge using the calculated remaining capacity The current charge state is updated and set to an accurate value even in a non-equilibrium state, and the error accumulated in the charge state obtained by the current integration method before that is set. Therefore, it is possible to accurately determine the state of charge of the original battery to be accurately determined and integrated, and to accurately measure the state of charge of the battery. It is possible to provide a vehicle battery state-of-charge measurement method and apparatus that can be measured easily.
[0133]
According to the configuration described in

claim

2 or 7, the current charge state is updated and set to an accurate value every time the engine is started, and the charge previously obtained by the current integration method is set. It is possible to provide a vehicle battery charge state measurement method and apparatus that can eliminate errors accumulated in the state.
[0134]
According to the configuration described in

claim

3 or 8, the discharge current exceeds the predetermined value at the initial stage of discharge as in the case of the constant load, even if it is in a non-equilibrium state and is not discharged to the constant load. The current charge state is updated and set to an accurate value for each discharge to other loads that decrease to the predetermined value or less after that, and the charge state previously obtained by the current integration method is set. Accumulated errors can be eliminated, making it difficult for large accumulated errors to occur due to continuous accumulation of charge / discharge current over a long period of time, and for vehicles that can measure the state of charge of batteries more accurately A battery charge state measuring method and apparatus can be provided.
[0135]
According to the configuration of claim 4 or 9, the current state of charge is updated and set to an accurate value at least every time the headlamp is turned on or the drive motor is driven. In addition, it is possible to provide a vehicle battery state-of-charge measurement method and apparatus that can eliminate the error accumulated in the state of charge obtained by the current integration method.
[0136]
According to the configuration of

claim

5 or 10 described above, the battery terminal voltage and discharge current measured periodically are collected, stored, stored, used for the latest predetermined time, and decreased from the predetermined value. The present invention provides a vehicle battery charge state measuring method and apparatus capable of performing processing for obtaining voltage-current characteristics at an arbitrary point in time and capable of being performed without increasing the processing speed. Can do.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of a vehicle battery charge state measuring apparatus according to the present invention.
FIG. 2 is an explanatory diagram partially showing a schematic configuration of a vehicle battery charge state measuring apparatus according to an embodiment of the present invention to which the vehicle battery charge state measuring method of the present invention is applied.
FIG. 3 is a graph showing a correlation between terminal voltage and discharge time in constant current discharge of a battery.
FIG. 4 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.
5 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.
6 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. 4. FIG.
FIG. 7 is a graph in which voltage-current characteristics of a battery corresponding to each capacity are developed on the same plane.
8 is a graph showing the relationship between the battery capacity at the virtual discharge current value showing the linear characteristic in the graph of FIG. 6 and the estimated voltage estimated from the voltage-current characteristic shown in FIG.
FIG. 9 is a graph showing the content of a voltage drop that occurs during battery discharge.
10 is a flowchart showing a part of processing performed by a CPU in accordance with a control program stored in a ROM of the microcomputer of FIG. 2. FIG.
11 is a flowchart showing another part of processing performed by the CPU in accordance with a control program stored in the ROM of the microcomputer of FIG. 2;
12 is a flowchart showing still another part of the processing performed by the CPU in accordance with the control program stored in the ROM of the microcomputer of FIG. 2. FIG.
FIG. 13 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.
14 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. 15 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 that is not in an equilibrium state.
[Explanation of symbols]
5 Constant load (cell motor)
13 battery
23a-1 Current measurement means
23a-2 Accumulated charge state measuring means
23a-3 Voltage measuring means
23a-4 Voltage-current characteristic determining means
23a-5 first charge state update setting means
23a-6 Residual voltage drop value storage means
23a-7 second charge state update setting means
23b Measurement voltage / current storage means (RAM)

Claims

The charging current and discharging current of a battery mounted on and used in a vehicle running with the engine as a power source are periodically measured, and the charging current measured periodically is added to the current charging state of the battery, and In the vehicle battery charge state measurement method for measuring the charge state of the battery by performing subtraction from the current charge state of the battery of the discharge current measured periodically,
Based on an expression representing the voltage-current characteristics of the battery in various capacities, a value of a current in which the voltage linearly changes with respect to the capacity is obtained in advance as a virtual current,
The terminal voltage of the battery in an equilibrium state is measured as an open circuit voltage, the remaining capacity of the battery is calculated based on the measured open circuit voltage, and the current charge state is calculated using the remaining capacity obtained by the calculation Update and set
When discharging to a constant load by the battery in an equilibrium state, the terminal voltage and the discharge current of the battery during the period in which the discharge current increases in excess of a predetermined value and then decreases to the predetermined value or less in the initial stage. At the time of discharge of the constant load obtained by substituting the virtual current into an expression representing the voltage-current characteristic indicating the correlation between the terminal voltage of the battery and the discharge current measured periodically. the difference value between the value of the value and the open circuit voltage estimated voltage of the battery is the difference between the residual voltage drop due to the influence of the residual polarization at the end of discharge in the initial stage of discharge to the constant load by the battery Obtain in advance as the residual voltage drop difference value ,
For each discharge to the constant load by the battery in an unbalanced state, the terminal voltage of the battery measured periodically during a period in which the discharge current increases beyond a predetermined value and then decreases below the predetermined value; Obtaining an expression representing the voltage-current characteristic from the discharge current , substituting the virtual current into the obtained expression representing the voltage-current characteristic, and obtaining the remaining voltage obtained in advance from the current estimated voltage value of the battery. An estimated open circuit voltage is obtained by adding a drop difference value , and the current state of charge is updated and set using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage. A vehicle battery state-of-charge measuring method characterized by the above.

The vehicle battery charge state measuring method according to claim 1, wherein the constant load is a cell motor for starting the engine of the vehicle.

Similar to the constant load by the battery in the non-equilibrium state, the discharge current is predetermined for each discharge to another load that decreases below the predetermined value after the discharge current increases beyond the predetermined value in the initial stage of discharge. An equation representing the voltage-current characteristic is obtained from the terminal voltage and discharge current of the battery periodically measured during a period of increasing beyond the value and decreasing below the predetermined value, and the obtained voltage − An estimated open circuit voltage is obtained by adding the previously obtained residual voltage drop difference value to the current estimated voltage value of the battery obtained by substituting the virtual current value into an expression representing current characteristics, and obtaining the estimated The vehicle battery charge state measurement method according to claim 1 or 2, wherein the current charge state is updated and set using a remaining capacity of the battery calculated based on an open circuit voltage.

The other load is at least one of a headlamp through which a rush current flows when lit, and a drive motor through which the rush current flows when the vehicle has an auxiliary drive source for assisting an engine as a driving power source. The vehicle battery charge state measuring method according to claim 3.

The battery terminal voltage and discharge current measured periodically are collected and stored for the latest predetermined time, and stored.
Using the battery terminal voltage and discharge current for the latest predetermined time stored, the discharge current increases beyond a predetermined value at the initial stage of discharge and then decreases below the predetermined value. The vehicle battery charge state measuring method according to any one of claims 1 to 4, wherein an expression representing the voltage-current characteristic during a certain period is obtained.

Current measuring means for periodically measuring a charging current and a discharging current of a battery mounted on and used in a vehicle running with an engine as a power source, and the battery having the charging current periodically measured by the current measuring means An integration type charging state measuring means for measuring the charging state of the battery by respectively adding to the current charging state and subtracting the discharge current periodically measured by the current measuring means from the current charging state of the battery; In a vehicle battery charge state measuring device comprising:
Voltage measuring means for periodically measuring the terminal voltage of the battery;
Voltage for determining an expression representing a voltage-current characteristic indicating a correlation between the terminal voltage and the discharge current from the terminal voltage and the discharge current of the battery periodically measured by the voltage measurement unit and the current measurement unit, respectively. Current characteristic determining means;
The voltage measuring means measures the terminal voltage of the battery in an equilibrium state as an open circuit voltage, calculates the remaining capacity of the battery based on the measured open circuit voltage, and uses the remaining capacity obtained by the calculation First charging state update setting means for updating and setting the current charging state;
During discharge to a constant load by the battery in an equilibrium state, the voltage measuring means and the current measurement are performed during a period in which the discharge current increases in excess of a predetermined value and then decreases to a predetermined value or less after the initial stage. The voltage-current characteristic determining means determines an expression representing a voltage-current characteristic indicating a correlation between the terminal voltage and the discharge current from the battery terminal voltage and the discharge current measured periodically by the means, The voltage is expressed linearly with respect to the capacity obtained in advance as a virtual current based on the expression representing the voltage-current characteristics of the battery in various capacities, based on the formula representing the voltage-current characteristics determined by the voltage-current characteristics determining means. the difference value between the value of the value and the open circuit voltage estimated voltage of the battery by substituting the value of the varying current during the discharge of the constant load, the initial time of discharge to the constant load by the battery A residual voltage drop difference value storage means for storing as a residual voltage drop difference value which is the difference between the residual voltage drop due to the influence of the residual polarization at the time of floor discharge end,
During each discharge of the unbalanced battery to the constant load by the voltage measuring means and the current measuring means during a period in which the discharge current increases beyond a predetermined value and then decreases below the predetermined value. The voltage-current characteristic determining unit determines an expression representing the voltage-current characteristic from the terminal voltage and discharge current of the battery measured periodically, and the voltage-current characteristic determining unit determines the voltage-current characteristic determining unit. by substituting the virtual current expression for the search of the current value to the residual voltage drop difference value previously stored by adding to the estimated open-circuit voltage residual voltage drop difference value in the storage means of the estimated voltage of the battery determined And second charge state update setting means for updating and setting the current charge state using the remaining capacity of the battery calculated based on the obtained estimated open circuit voltage. Vehicle battery charge state measuring device.

The vehicle battery charge state measuring device according to claim 6, wherein the constant load is a cell motor for starting an engine of the vehicle.

The second charge state update setting means is similar to the constant load by the battery in the non-equilibrium state, and the discharge current increases beyond a predetermined value at the initial stage of discharge and then decreases below the predetermined value. For each discharge to the load, during the period in which the discharge current increases beyond a predetermined value and then decreases below the predetermined value, the voltage of the battery measured periodically by the voltage measuring means and the current measuring means respectively. The voltage-current characteristic determining unit is caused to determine an expression representing the voltage-current characteristic from the terminal voltage and the discharge current, and the virtual current value is converted into an expression representing the voltage-current characteristic determined by the voltage-current characteristic determining unit. substituted by seeking current estimated voltage value to the residual voltage drop difference value storage means previously stored residual voltage drop difference value estimating an open circuit voltage by adding of the battery obtained, the obtained estimated open circuit voltage On the basis of the Calculated by said current vehicle battery charge state measuring device according to claim 6, wherein the updates and sets the charge state with the remaining capacity of the battery.

The other load is at least one of a headlamp through which a rush current flows when lit, and a drive motor through which the rush current flows when the vehicle has an auxiliary drive source for assisting an engine as a driving power source. The vehicle battery state-of-charge measuring device according to claim 8.

A measurement voltage / current storage means for collecting, storing and storing the terminal voltage and discharge current of the battery measured periodically for the latest predetermined time,
The voltage-current characteristic determining means obtains an expression representing the voltage-current characteristic using the terminal voltage and discharge current of the battery for the latest predetermined time stored in the measured voltage / current storage means. The vehicle battery state-of-charge measuring device according to any one of claims 6 to 9.