JP4017936B2 - Battery pure resistance measuring method and apparatus - Google Patents

Description

【００５７】
この行列をａ，ｂ，ｃについて解いて得られる近似式の各係数を求める式は以下のようになる。そして、サンプリングによって放電電流Ｉと端子電圧Ｖを周期的に測定する毎に計算して求めたΣＩ，ΣＩ² ，ΣＩ³ ，ΣＩ⁴ ，ΣＶ，ΣＶ²，ΣＶＩ，ΣＶＩ² を利用し、この式に基づいて計算を行えば近似式の各係数が求められる。
【００５８】
【数２】

【００５９】
【数３】

【００６０】
【数４】

【００６１】
【数５】

【００６２】
図４中おいて、電流増加方向の近似曲線の切片と電流減少方向の近似曲線の切片の電圧差は、電流が流れていない０（Ａ）の時の電圧差であるため、純抵抗と活性化分極による電圧降下を含まない、放電によって新たに発生した濃度分極成分のみによる電圧降下と考えられる。従って、この電圧差を電流０（Ａ）点の濃度分極をＶpolc0 とすると、この濃度分極Ｖpolc0 は、突入電流の大きさに電流の流れた時間を乗じて積算したもの、すなわちＡｈ（短時間なので、以下Ａsec で表す）に比例する項として求められる。
【００６３】
次に、この電流０（Ａ）点の濃度分極Ｖpolc0 を利用して電流ピーク値の濃度分極を算出する方法を説明する。今、電流ピーク値の濃度分極をＶpolcp とすると、Ｖpolcp は次式のように表される。
Ｖpolcp ＝［（電流増加時のＡsec ）／（放電全体のＡsec ）］×Ｖpolc0 ……（３）
なお、放電全体のＡsec は次式で表される。
放電全体のＡsec ＝（電流増加時のＡsec ＋電流減少時のＡsec ）
【００６４】
上述のようにして求めたピーク値における濃度分極Ｖpolcp を式（１）のピーク値における電圧に加算して、図５に示すように、ピーク値における濃度分極成分を削除する。なお、ピーク値における濃度分極成分を削除した後の電圧をＶ１とすると、Ｖ１は次式で表される。
Ｖ１＝a1Ｉp²＋b1Ｉp ＋c1＋Ｖpolcp
Ｉp はピーク値における電流値である。
【００６５】
次に、上述のようにして求めたＶ１を利用して次式で表される、図５に示すような純抵抗と活性化分極だけの電圧降下曲線を求める。
Ｖ＝a3Ｉ² ＋b3Ｉ＋c3 ……（４）
【００６６】
式（１）および（４）で表される特性の初期状態、すなわち、電流が０（Ａ）の点に注目すると、初期状態での分極は等しいので、c3＝c1である。また、電流増加の初期状態から電流は急激に増加するが、濃度分極の反応は遅く、反応がほとんど進行していないとすると、式（１）および（４）の電流が０（Ａ）の点の微分値は等しくなるので、b3＝b1である。従って,c3＝c1 、b3＝b1 を代入することで、式（４）は
Ｖ＝a3Ｉ² ＋b1Ｉ＋c1 ……（５）
と書き直され、未知数はa3のみとなる。
【００６７】
そこで、式（５）に電流増加のピーク値の座標（Ｉp 、Ｖ１）を代入してa3について整理すると、次式が求められる。
a3＝（Ｖ１−b1Ｉp −c1）／Ｉp²
従って、純抵抗と活性化分極成分だけの電圧降下曲線の式（４）が式（５）によって決定される。
【００６８】
一般に、純抵抗は化学反応にて生じるものでないので、バッテリの充電状態（ＳＯＣ）、温度などが変わらなければ一定であるので、１回のスタータモータ作動の間は一定であるといえる。これに対し、活性化分極抵抗は、イオン、電子の受渡しの際の化学反応に伴って生じる抵抗であるので、濃度分極と相互に影響し合うこともあって、活性化分極の電流増加曲線と電流減少曲線は完全に一致しないことから、式（５）は濃度分極成分を除いた純抵抗と活性化分極の電流増加方向の曲線であるということができる。
【００６９】
続いて、電流減少曲線からの濃度分極成分の削除の仕方を、以下説明する。純抵抗と活性化分極の電流減少方向の関係式は、電流ピーク値における濃度分極の削除と同様の方法で可能である。ピーク値以外の２点をＡ点およびＢ点とし、各点における濃度分極ＶpolcA 、ＶpolcB を次式のようにして求める。
ＶpolcA ＝［（電流増加時開始からＡ点までのＡsec ）／（放電全体のＡsec ）］×Ｖpolc0 ……（６）
ＶpolcB ＝［（電流増加時開始からＢ点までのＡsec ）／（放電全体のＡsec ）］×Ｖpolc0 ……（７）
【００７０】
上式（６）および（７）によって、ピーク値以外に濃度分極成分を削除した２点が求まったら、この２点とピーク値との３点の座標を利用して次式で表される、図６に示すような、純抵抗と活性化分極の電流減少方向曲線が求められる。
Ｖ＝a4Ｉ² ＋b4Ｉ＋c4 ……（８）
なお、式（８）の係数a4、b4、c4は、２点Ａ及びＢとピーク点の電流値と電圧値とを、式（８）にそれぞれ代入して立てた３点の連立方程式を解くことによって決定できる。
【００７１】
次に、純抵抗の算出の仕方を説明する。上式（５）で表される濃度分極成分を削除した純抵抗と活性化分極の電流増加方向の曲線と、式（８）で表される同じく濃度分極成分を削除した純抵抗と活性化分極の電流減少方向の曲線との相違は、活性化分極成分の違いによるものであるので、活性化分極成分を除けば純抵抗が求められる。
【００７２】
ところで、活性化分極が互いに等しい値となる両曲線のピーク値に着目し、ピーク値での電流増加の微分値Ｒ１と電流減少の微分値Ｒ２とを次式によって求める。
Ｒ１＝２×a3×Ｉp ×b3 ……（10）
Ｒ２＝２×a4×Ｉp ×b4 ……（11）
上式によって求められる微分値Ｒ１およびＲ２の差は、一方が活性化分極の増加方向でのピーク値であるのに対し、他方が減少方向でのピーク値であることに基因する。そして、突入電流に相当する模擬的な放電として、０（Ａ）から２００Ａまで０．２５秒かけて増加し、同じ時間をかけてピーク値から０（Ａ）まで減少する放電を電子負荷を使用してバッテリに行わせた場合には、ピーク値近傍での両者の変化率が等しく、両者の中間に純抵抗による電流−電圧特性が存在すると理解できるので、両微分値を加算して２で割ることによって、純抵抗Ｒを次式によって求めることができる。
Ｒ＝（Ｒ１＋Ｒ２）／２ ……（12）
【００７３】
以上は、突入電流に相当する模擬的な放電を電子負荷を使用してバッテリに行わせた場合について説明したが、実車両の場合には、上述したようにスタータモータとして直流モータを使用しているとき、界磁コイルに突入電流が流れる以前に放電電流が流れていることがあり、また突入電流が流れている間に電流はピークに達し、クランキングはピークに達した後ピーク電流の半分以下に低下し、突入電流が終了した後には定常電流で作動しており、模擬的な放電の場合と異なり、突入電流は必ずしも０（Ａ）から始まり、０（Ａ）では終わっていない。このように実車では、突入電流以外の要素の放電電流が流れているので、これらを上述した近似式を求めるために使用すると、突入電流のみの近似式とは異なった式が得られて純抵抗を正確に求めることを難しくするので、突入電流による放電電流の測定データのみを使用して近似式を求めることが必要になる。
【００７４】
そこで、放電電流が予め定めた第１の所定値ＩA を越えて増大した後、ピーク値Ｉp に達するまでの測定データを使用して電流増加期間の近似式を求め、ピーク値から予め定めた第２の所定値ＩB に低下するまでの測定データを使用して電流減少期間の近似式を求めるようにする。なお、第１の所定値ＩA としては通常の負荷では電流増加方向では流れない下限値が、第２の所定値ＩB としては通常負荷で流れる上限値がそれぞれ定められる。すなわち、突入電流が流れ始める前とクランキング期間については、突入電流の流れている期間とは異質の現象が生じているので、この期間のバッテリの放電電流と端子電圧については、電流増加方向及び電流減少方向の電流−電圧特性を決定するためのデータとしては使用しないようにする。
【００７５】
また、界磁コイルを有する直流モータの場合、電流増加方向は３ミリ秒（ｍｓｅｃ）という短時間で終了してしまい、電流増加ピーク値ではほとんど濃度分極が発生しない早い電流の変化であるが、電流減少方向は電流増加方向に比べて例えば１５０ｍｓｅｃという長い時間電流が流れるので、減少方向とはいえ、大きな濃度分極が発生する。
【００７６】
このような状況で、界磁コイルを有する直流モータでの実車両では、図７に示すように、電流増加方向は電流増加開始点とピーク値の２点間を結ぶ直線にて近似することができ、しかもこのピーク値５００（Ａ）での濃度分極の発生は０（Ａ）と近似することも可能である。この場合には、電流増加方向については、ピーク値の微分値としては、電流増加方向の近似直線の傾きを使用することになる。
【００７７】
ただし、このような場合には、電流増加方向の近似直線の傾きと、電流減少方向の二次の近似式のピーク点における接線の傾きとを単純に加算平均することはできない。何故ならば、このような状況では、ピーク点までとそれ以降で、活性化分極の発生度合いが全く異なり、ピーク値近傍での両者の変化率が等しくなるという前提が成立しなくなるからである。
【００７８】
このような場合には、純抵抗を求めるに当たって、濃度分極による電圧降下を除いた第１及び第２の近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値、すなわち、傾きに、突入電流が流れている総時間に占める単調増加期間及び単調減少期間の時間の割合をそれぞれ乗じた上で加算すればよい。すなわち、総時間を単調増加及び単調減少にそれぞれ要した時間で比例按分した按分率を各傾きに乗じた上で加算することになる。このようにすることによって、活性化分極と濃度分極とが相互に影響し合うことを考慮して純抵抗を求めることができる。
【００７９】
しかし、上述した実車の場合には、突入電流は０（Ａ）から始まらないし、０（Ａ）で終わらないので、近似式は第１の所定値からピーク値に達するまでの測定データと、ピーク値から第２の所定値までの測定データを使用して求めざるを得ない。従って、突入電流が流れている総時間に占める単調増加期間及び単調減少期間の時間の割合は単純には求められない。そこで、第１の所定値ＩA からピーク値Ｉp に達するまでの測定データと、ピーク値Ｉp から第２の所定値ＩB までの測定データに基づいて、突入電流が流れている総時間と、単調増加期間及び単調減少期間の時間の求め方を、突出電流−時間特性を三角形に近似させて示した図８を参照して以下説明する。
【００８０】
図８に示すように、第１の所定値ＩA と、ピーク値Ｉp と、第２の所定値ＩB と、第１の所定値ＩA からピーク値Ｉp までとピーク値Ｉp から第２の所定値ＩB までの各サンプリング回数にサンプリング間隔を乗じて求めた時間Ｔa 及びＴb とに基づいて、点線で示すような測定データに基づく電流−時間特性が描けるが、この点線で示す特性を電流０（Ａ）の点まで延長して三角形に近似した電流−時間特性を得る。そして、電流０（Ａ）の点からピーク値までの時間Ｔa′と、ピーク値から電流０（Ａ）の点までの時間Ｔb′を単調増加期間及び単調減少期間の時間として、次式によって求めることができ、両者を合算した時間を総時間として求めることができる。
Ｔa′＝Ｉp ・Ｔa ／（Ｉp −ＩA ）
Ｔb′＝Ｉp ・Ｔb ／（Ｉp −ＩB ）
【００８１】
要するに、活性化分極は原則電流値に応じた大きさのものが生じるが、その時々の濃度分極量に左右され、原則通りには生じることにならず、濃度分極が小さければ活性化分極も小さくなり、大きければ大きくなる。何れにしても、濃度分極成分による電圧降下を除いた２つの近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値の中間の値をバッテリの純抵抗の値として測定することができる。
【００８２】
なお、最近の車両では、モータとしては、マグネットモータなどのＤＣブラッシレスなどの三相入力を必要とする交流モータが使用されることが増えてきている。このようなモータの場合、突入電流はそれ程早く短時間にピーク値に達することがなく、１００ｍｓｅｃほどの時間を要し、電流増加方向においても濃度分極の発生が起こるので、上述した模擬的な放電の場合と同様に、電流増加方向の電流変化曲線は二次近似することが必要になる。
【００８３】
また、活性化分極の電流減少方向の近似をする場合、ピーク値とそれ以外の２点を定める際、図９に示すように、Ｂ点として電流０（Ａ）の点を使用すると、近似式を求める際の計算を簡略化することができる。
【００８４】
さらに、例えば、ピーク電流の１／２程度の電流値に対応する点に濃度分極の削除した点を定めた場合、図１０に示すように、この点とピーク値の２点を結ぶ直線に一次近似してもよい。この場合、電流減少方向については、ピーク値の微分値としては、電流減少方向の近似直線の傾きを使用することになるが、二次曲線を使用したものと変わらない、精度のよい純抵抗が求められる。
【００８５】
以上要するに、濃度分極成分による電圧降下を除いた２つの近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値の中間の値をバッテリの純抵抗の値として測定することができる。
【００８６】
そこで、バッテリの純抵抗測定方法を、負荷として、増加する放電電流及び減少する放電電流のいずれにおいても濃度分極の発生を伴う突入電流が流れるような例えばスタータモータが使用されている場合について具体的に説明する。
【００８７】
スタータモータが始動されると、バッテリからは第１の所定値を越えて単調増加しピーク値から第２の所定値に単調減少する突入電流が放電電流として流れる。従って、バッテリの放電電流と端子電圧とを、例えば１００マイクロ秒（μｓｅｃ）の周期にてサンプリングしていることによってバッテリの放電電流を監視し、放電電流が第１の所定値を越えた後の放電電流と端子電圧とを周期的に測定し、バッテリの放電電流と端子電圧との組を順次得ることができ、このサンプリングによって得た放電電流の測定値によってピーク値を求めことができる。そして、ピーク値から減少する放電電流が第２の所定値以下になる時点までバッテリの放電電流と端子電圧との組を順次得ることができる。
【００８８】
このようにしてバッテリの放電電流と端子電圧との組が得られる毎に、放電電流の増加時については上式（１）の近似式Ｖ＝a1Ｉ² ＋b1Ｉ＋c1、減少時については上式（２）の近似式Ｖ＝a2Ｉ² ＋b2Ｉ＋c2の各係数を決定して近似式を求めるため、ΣＩ，ΣＩ² ，ΣＩ³ ，ΣＩ⁴ ，ΣＶ，ΣＶ² ，ΣＶＩ，ΣＶＩ² の計算を逐次行っていき、放電電流の単調増加期間及び単調減少期間の測定データに基づいて計算したΣＩ，ΣＩ² ，ΣＩ³ ，ΣＩ⁴ ，ΣＶ，ΣＶ² ，ΣＶＩ，ΣＶＩ² を用いて各係数についての計算を行うことで、最小二乗法により、端子電圧と放電電流との相関を示す増加する放電電流及び減少する放電電流に対する電流−電圧特性について式（１）及び（２）に示すような２つの二次近似式が求められる。次に、この２つの近似式から濃度分極成分による電圧降下を削除し、濃度分極成分を含まない修正した二次近似式が求められる。
【００８９】
このために、まず、上述のようにして求めた式（１）及び（２）の近似式の電流が流れていない０（Ａ）の時の電圧差を、純抵抗と活性化分極による電圧降下はなく、濃度分極によるものであるとして求める。また、この電圧差を利用して、増加する放電電流についての電流−電圧特性の近似式（１）上の電流ピーク値での濃度分極成分による電圧降下を求める。このために、濃度分極は、電流の大きさに電流の流れた時間を乗じた電流時間積によって変化していることを利用する。なお、この電流時間積を求めるための時間としては、求め方を上述したＴa′及びＴb′を用いる。
【００９０】
増加する放電電流についての電流−電圧特性の近似式上の電流ピーク値での濃度分極成分による電圧降下が求まったら次に、濃度分極成分の含まない近似式と含む近似式のいずれも定数及び一次係数が等しいとして、含まない近似式の二次係数を定め、増加する放電電流についての電流−電圧特性の近似式について修正した二次近似式（５）を求める。
【００９１】
次に、減少する放電電流に対する電流−電圧特性について近似式（２）から濃度分極成分の含まない近似式を求める。このために、ピーク値以外に濃度分極成分を削除した２点を求める。この際に、濃度分極は、電流の大きさに電流の流れた時間を乗じた電流時間積によって変化していることを利用する。そして、ピーク値以外に濃度分極成分を削除した２点が求まったら、この２点とピーク値との３点の座標を利用して、減少する放電電流についての電流−電圧特性の近似式（２）について修正した二次近似式（８）を求める。
【００９２】
上式（５）で表される濃度分極成分を削除した純抵抗と活性化分極の電流増加方向の修正二次近似式と、式（８）で表される濃度分極成分を削除した純抵抗と活性化分極の電流減少方向の修正二次近似式は、活性化分極成分の相違によるものであるので、活性化分極成分を除けば純抵抗が求められる。このために、両近似式のピーク値に着目し、ピーク値での電流増加の微分値と電流減少の微分値との差は、一方が活性化分極の増加方向であるのに対し、他方が減少方向であることに基因するものであるが、ピーク値近傍での両者の変化率の中間に純抵抗による電流−電圧特性が存在するとし、両微分値に突入電流が流れている総時間（Ｔa′＋Ｔb′）に占める単調増加期間及び前記単調減少期間の時間Ｔa′、Ｔb′の割合をそれぞれ乗じた上で加算することによって、純抵抗を求める。
【００９３】
例えば、電流増加時間が３ｍｓｅｃ、電流減少時間が１００ｍｓｅｃとし、ピーク値での電流増加の微分値をＲpolk1 、電流減少の微分値をＲpolk2 とすると、以下のようにして純抵抗Ｒを算出することができる。
Ｒ＝Ｒpolk1 ×１００／１０３＋Ｒpolk2 ×３／１０３
【００９４】
上述したようなことを可能にして本発明のバッテリの純抵抗測定方法を実施する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。
【００９５】
図２は本発明のバッテリの純抵抗測定方法を適用した本発明の一実施形態に係る車載バッテリの純抵抗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載バッテリの純抵抗測定装置は、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。
【００９６】
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。
【００９７】
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。
【００９８】
なお、車両の場合、イグニッションスイッチ又はアクセサリ（ＡＣＣ）スイッチがオンされることによって、そのときオン状態にある負荷への電源供給に伴い、バッテリの放電電流が流れる。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スタータ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、短時間に大きな突入電流が流される。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のオン状態に移行し、これに伴ってバッテリ１３から流れる放電電流は、負荷に応じた定常電流に移行する。
【００９９】
話を構成の説明に戻すと、本実施形態の車載バッテリの純抵抗測定装置１は、アシスト走行用のモータやスタータモータとして機能するモータジェネレータ５等、電装品に対するバッテリ１３の放電電流Ｉや、ジェネレータとして機能するモータジェネレータ５からのバッテリ１３に対する充電電流を検出する電流センサ１５と、バッテリ１３に並列接続した１Ｍオーム程度の抵抗値を有し、バッテリ１３の端子電圧Ｖを検出する電圧センサ１７とを備えている。
【０１００】
また、本実施形態の車載バッテリの純抵抗測定装置１は、上述した電流センサ１５及び電圧センサ１７の出力がインタフェース回路（以下、「Ｉ／Ｆ」と略記する。）２１におけるＡ／Ｄ変換後に取り込まれるマイクロコンピュータ（以下、「マイコン」と略記する。）２３をさらに備えている。
【０１０１】
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が接続されており、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）のスイッチ等が、さらに接続されている。
【０１０２】
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。
【０１０３】
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、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、各種の処理のために使用される。
【０１０４】
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１１のフローチャートを参照して説明する。
【０１０５】
イグニッション（ＩＧ）スイッチがオンされバッテリ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、１００μｓｅｃのサンプリング周期での放電電流及び端子電圧のサンプリングを開始し（ステップＳ１）、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変換値を対にしてＩ／Ｆ２１を介して測定データを読み込む処理を実行して放電電流が予め定めた第１の所定値ＩA を越えるのを監視する。放電電流が第１の所定値ＩA を越えたときには、突入電流が流れ始めたと判断して近似式を求めるための処理に入る。放電電流がピーク値に達しているかかどうかによって近似式を求めるための処理を切り替える（ステップＳ３）。なお、放電電流がピーク値に達したかどうかの判断は、突出電流が増加している期間の近似式を求めるための後述する処理の途中で行う。
【０１０６】
ピーク電流に達していないとき（ステップＳ３の判定がＮのとき）には、サンプリング値を前回のサンプリング値と比較し（ステップＳ４）、比較の結果、前回のサンプリング値よりも増加しているとき（ステップＳ４の判定がＹのとき）には、サンプリングした放電電流と端子電圧とに基づいて、電流増加時の近似式を求めるための各Σ項の演算を行う（ステップＳ５）。また、比較の結果、前回のサンプリング値よりも減少しているとき（ステップＳ４の判定がＮのとき）には、サンプリング値が連続してｎ回減少しているかどうかを監視し（ステップＳ６）、連続してｎ回減少しているとき（ステップＳ６の判定がＹのとき）には、放電電流がピーク値から減少に転じていると判断する（ステップＳ７）。連続してｎ回減少していないとき（ステップＳ６の判定がＮのとき）には、サンプリングした放電電流と端子電圧とに基づいて、電流減少時の近似式を求めるための各Σ項の演算を行う（ステップＳ８）。
【０１０７】
電流増加時の各Σ項の演算を行ったとき（ステップＳ５）には、そのときステップＳ８において演算した電流減少時の各Σ項の演算結果があるとき（ステップＳ９がＹのとき）には、その結果を電流増加時の各Σ項に加算する（ステップＳ１０）とともに電流減少時の各Σ項をクリアする（ステップＳ１１）。これは突入電流の電流増加期間において、一時的にサンプリング電流値が減少していてもピーク値に達していない場合には、測定データとして近似式に反映するようにするための処理である。また、ステップＳ８の演算は、サンプリング値が連続してｎ回減少したときのために、ピーク値が判断される以前の連続してｎ回減少していない期間のサンプリング値に基づいて、電流減少時の近似式を求めるための各Σ項の演算を先行して行っておくためのものである。
【０１０８】
ピーク電流の判断がされた後（ステップＳ３がＹのとき）には、サンプリングした放電電流と端子電圧とに基づいて、電流減少時の近似式を求めるための各Σ項の演算を行う（ステップＳ１２）。このとき、ステップＳ８において演算した電流減少時の各Σ項の演算結果が残っているので、ステップＳ８の演算結果に続けて演算を行うことになる。その後に、放電電流が予め定めた第２の所定値ＩB を越えて減少するかどうかを監視し（ステップＳ１３）、放電電流が第２の所定値ＩB を越えて減少するまで（ステップＳ１３がＹとなるまで）、ステップＳ１〜３並びにステップＳ１２及びＳ１３を繰り返し実行し、電流減少時の各Σ項の演算を繰り返す。放電電流が第２の所定値ＩB を越えて減少したとき（ステップＳ１３がＹのとき）には、突入電流が終了したと判断して近似式を求めるための処理を終了し、ステップＳ５で演算した電流増加時の各Σ項を用いて電流増加時の近似式を、ステップＳ１２で演算した電流減少時の各Σ項を用いて電流減少時の近似式をそれぞれ求める。
【０１０９】
なお、フローチャートには明記していないが、求めた近似式が有効なものであるかどうかの判定を行うことが当然に必要であり、この判定は、近似式の各係数を決定するための各Σ項の演算結果を利用して求めることができる電流増加時と電流減少時の相関係数と、ピーク電流の大きさとを予め定めた値と比較することによって行うことができる。
特に、第１及び第２の所定値を設けることによって、誤差要因を取り除くことができる。
【０１１０】
求まった二次近似式からバッテリの純抵抗を求めるための演算処理を実行する演算処理においては、二次式に濃度分極成分による電圧降下が含まれている場合、この電圧降下を除いた修正二次近似式を求める修正二次近似式算出処理を行い、この修正二次近似式を用いてバッテリの純抵抗を求めるための演算処理を実行することになり、この場合には、増加する放電電流及び減少する放電電流に対する電流−電圧特性の２つの修正二次近似式のピーク値での微分値を算出した上で、２つの微分値の中間の値をバッテリの純抵抗として求める演算を行う。そして、この求めたバッテリの純抵抗は種々の目的で使用するため、ＲＡＭ２３ｂのデータエリアに格納されて記憶される。
【０１１１】
この微分値の中間の値を求める方法としては、突入電流の流れ形によって２つの方法がある。
突入電流の増加方向の時間と減少方向の時間とがほぼ等しいときには、２つの微分値の加算平均値を純抵抗として求める演算を行う。
これに対して、突入電流の増加方向の時間と減少方向の時間とが大きく異なるときには、増加する放電電流に対する電流−電圧特性の修正二次近似式のピーク値での微分値に、放電電流の総時間に占める増加する放電電流の流れた時間の比率を乗じたものと、減少する放電電流に対する電流−電圧特性の２つの修正二次近似式のピーク値での微分値に、放電電流の総時間に占める減少する放電電流の流れた時間の比率を乗じたものとを加算した加算値を純抵抗として求める演算を行う。
いずれの方法で純抵抗を求めた場合にも、バッテリの純抵抗は２つの微分値の中間の値として求められる。
【０１１２】
また、図１１のフローチャートに示した例では、第１及び第２の近似式が共に二次近似式としているが、第１の近似式が一次近似式であるときには、修正近似式を求める処理は当然に不要になる。そして、この場合には、一次式の傾きを微分値に代えて利用することになる。
【０１１３】
また、本実施形態の車載バッテリの純抵抗測定装置１ではフローチャートにおけるステップＳ５が請求項中の電流・電圧測定手段に対する処理となっており、ステップＳ１２が請求項中の近似式算出手段に対応する処理となっており、ステップＳ１３が請求項中の演算手段に対応する処理となっている。
【０１１４】
次に、上述のように構成された本実施形態の車載バッテリの純抵抗測定装置１の動作（作用）について説明する。
【０１１５】
まず、スタータモータの駆動開始に伴いバッテリ１３が放電を行っている状態で、スタータモータに第１の所定値を越えて単調増加しピーク値から第２の所定値に単調減少する突入電流が流れたときのバッテリの端子電圧と放電電流とが周期的に測定される。
【０１１６】
また、本実施形態の車載バッテリの純抵抗測定装置１では、測定データが、最小二乗法を適用して、電流−電圧特性の２次の近似曲線式を求めるのに適当なものであるかどうかが判定され、適当でないと判定されたときには、処理を途中で止めるようになっている。
【０１１７】
なお、上述した実施の形態では、スタータモータが駆動開始されるときの放電電流に含まれる突入電流についてのみ注目して本発明を実施しているが、大きさこそ異なるもののスタータモータと同様に駆動開始時に突入電流の流れるスタータモータ以外の負荷にも等しく適用することができる。
【０１１８】
なお、上述した実施の形態では、第１及び第２の近似式の放電電流０（Ａ）である点におけるバッテリの端子電圧の差を突入電流が０からピーク値に増加しピーク値から０（Ａ）に減少した期間に生じた総濃度分極成分による電圧降下と見なし、この総濃度分極成分に占める突入電流が０（Ａ）からピーク値に達するまでに生じる濃度分極成分による電圧降下を、第１及び第２の近似式の放電電流０（Ａ）である点におけるバッテリの端子電圧の差に、突入電流が０からピーク値に増加しピーク値から０（Ａ）に減少したときの電流時間積に対する０（Ａ）からピーク値までの電流時間積の比を乗じて求めているが、これを他の方法で求めることも可能であり、以下その方法を説明する。
【０１１９】
そもそも第１の近似式と第２の近似式の相違点が、濃度分極成分の違いであるとすると、両式の差の式を取ることによって、濃度分極成分が等しくなるピーク電流から電流値０（Ａ）になるまでの濃度分極について両者の差を顕著化することができるとともに、この差の式に基づいて電流値０からピーク電流値に至るまでの濃度分極成分の変化を予測しうる。
【０１２０】
上記式（１）及び（２）の差を取り、
ΔＶ＝ Ｖ＝（a1−a2）Ｉ² ＋（b1−b2）Ｉ＋（c1−c2 ） ……（２１）
を求める。これをプロットすると、図１２に示すように、ピーク電流値の点で濃度分極成分が０となり、電流値０までの濃度分極成分のみの変化を示す曲線が描かれる。そして、この式（２１）によって描かれる曲線を点線で示すようにピーク電流値の２倍の値の点まで延長することによって、電流値０からピーク電流値までの濃度分極成分の変化の様子を予測する。すなわち、電流増加と電流減少の濃度分極の相対的な変化を差の式に基づいて予測する。
【０１２１】
差の式は、電流値０からピーク電流までの濃度分極と、ピーク電流から電流値０までの濃度分極との発生変化の様子を、電流値０からピーク電流の間に凝縮して表していることになるので、この式によって表される曲線を２倍の放電電流のまで延長することによって、電流が電流値０−ピーク値−電流値と流れたときの濃度分極の変化の様子を想定することができるようになる。したがって、電流時間積と濃度分極との比例関係が乱れて電流時間積を用いて任意の点の濃度分極を推定したとき精度が悪化するような場合にも有効に適用可能である。
【０１２２】
そこで、電流値０である点の電圧値Ｖ0 と２倍のピーク電流値である点の電圧値Ｖ2Pとの差（Ｖ2P−Ｖ0 ）に対するピーク電流値である点の電圧値ＶP とピーク電流値の２倍の電流値である点の電圧値との差（Ｖ2P−ＶP ）の比を求め、これを電流増加方向の近似曲線の切片と電流減少方向の近似曲線の切片の電圧差である電流０（Ａ）点の濃度分極Ｖpolc0 に乗じることによって、ピーク電流値である点の濃度分極成分を予測する。この予測したピーク電流値である点の濃度分極成分は、上述したＶpolcp と同等に扱って、純抵抗と活性化分極だけの電圧降下曲線を求めることができる。
【０１２３】
電流減少曲線からの濃度分極成分を削除する場合にも、電流ピーク値における濃度分極の削除と同様の方法で可能である。すなわち、ピーク値以外の２点の電圧値を式（２１）により求め、電流値０（Ａ）である点の電圧値Ｖ0 と２倍のピーク電流値である点の電圧値Ｖ2Pとの差に対するピーク値以外の２点の電圧値とピーク電流値の２倍の電流値である点の電圧値との差の比を求め、これを電流増加方向の近似曲線の切片と電流減少方向の近似曲線の切片の電圧差である電流０（Ａ）点の濃度分極Ｖpolc0 に乗じることによって、各点の濃度分極成分を予測する。この予測した２点の濃度分極成分をピーク電流値である点の濃度分極成分とともに利用することで、純抵抗と活性化分極だけの電圧上昇曲線を求めることができる。
【０１２４】
以上説明したようにして求めた電圧降下曲線と電圧上昇曲線の修正近似式を利用して純抵抗を求める方法は、電流時間積を利用して求めた修正近似式の場合と同様にして行うことができるので、詳細な説明は省略する。
【０１２５】
【発明の効果】
以上説明したように、請求項１及び１４の発明によれば、負荷への電力供給に伴って流れるバッテリの放電電流が予め定めた第１の所定値を越えて増大したとき、バッテリの放電電流と該放電電流に対応する端子電圧とを周期的に測定し、この測定した放電電流と端子電圧との相関を示す、第１の所定値を越えてピーク値まで単調増加する放電電流に対する電流−電圧特性の第１の近似式とピーク値から予め定めた第２の所定値まで単調減少する放電電流に対する電流−電圧特性の第２の近似式とを求めているので、負荷への電力供給開始時に負荷に流れる突入電流が流れたときのバッテリの放電電流と該放電電流に対応する端子電圧との関係を示す電流−電圧特性を測定しているので、求めた２つの近似式には、突入電流以外の放電電流の要素を含まず、より正確な突入電流が流れたときのバッテリの電流−電圧特性を測定することができ、求めた第１及び第２の近似式に濃度分極成分による電圧降下を除いた第１及び第２の近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値の中間の値を求め、この求めた中間の値をバッテリの純抵抗の値として測定しているので、バッテリを通常状態で使用している際、すなわち、車両使用中でも、精度良くバッテリの純抵抗を測定できるバッテリの純抵抗測定方法及び装置を提供することができる。るバッテリの電流−電圧特性測定方法を提供することができる。
【０１２７】
上述した請求項２記載の発明によれば、放電電流及び端子電圧を測定しつつリアルタイムに近似式の演算が行え、しかもピーク値が予め定めた第３の所定値を越えないときには、純抵抗を測定するのに有効な測定データでないとして、近似式の演算を途中で止めることができるので、予めデータを蓄積する必要がなく、データ記憶するための大きな容量を必要としない。
【０１２８】
上述した請求項３記載の発明によれば、バッテリの純抵抗の値として測定するため求める中間の値が、濃度分極成分による電圧降下を除いた第１及び第２の近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値を加算平均して求められるので、ピーク値に対応する点での活性化分極の変化が等しくなる場合のバッテリの純抵抗を正確に測定できるバッテリの純抵抗測定方法を提供することができる。
【０１２９】
上述した請求項４記載の発明によれば、バッテリの純抵抗の値として測定するため求める中間の値が、濃度分極成分による電圧降下を除いた第１及び第２の近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値に、単調減少する放電電流が０まで減少したと想定したときの想定放電電流が流れる総時間に占める想定した単調増加期間及び想定した単調減少期間の時間の割合をそれぞれ乗じた上で加算して求められるので、ピーク値に対応する点での活性化分極の変化が等しくならない場合のバッテリの純抵抗を正確に測定できるバッテリの純抵抗測定方法を提供することができる。
【０１３０】
上述した請求項５記載の発明によれば、修正近似式が一次式となるときにはその傾き、二次式となるときにはピーク値における微分値を利用して中間の値を求めれば、純抵抗を測定することができるので、簡単な演算によって測定することができるバッテリの純抵抗測定方法を提供することができる。
【０１３１】
上述した請求項６記載の発明によれば、中間の値を、濃度分極成分による電圧降下を除いた第１及び第２の近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値に、想定放電電流が流れている総時間に占める想定単調増加期間及び想定単調減少期間の時間の割合をそれぞれ乗じた上で加算して求めていることにより、活性化分極と濃度分極とが相互に影響し合うことを考慮した中間の値を求め、バッテリの純抵抗の値として測定することができ、かつ、第１及び第２の近似式が二次式である場合、中間の値を求めるに当たって、第１及び第２の近似式から濃度分極成分による電圧降下を除いた第１及び第２の修正近似式を求め、該第１及び第２の修正近似式のピーク値に対応する点における単位電流変化当たりの２つの端子電圧変化の値を求めていることにより、修正近似式が二次式となるときにはピーク値における微分値を利用して中間の値を求めれば、純抵抗を測定することができ、しかも、第１及び第２の近似式の放電電流０である点におけるバッテリの端子電圧の差を想定放電電流が０からピーク値に増加しピーク値から０に減少した期間に生じた総濃度分極成分による電圧降下と見なし、この総濃度分極成分に占める想定放電電流が０からピーク値に達するまでに生じる濃度分極成分による電圧降下を求め、この電圧降下を除いた電圧値を、第１の二次近似式と定数及び一次係数を等しくした式に代入して二次係数を決定した二次式を第１の修正近似式として求めているので、精度良く濃度分極成分を除いた修正近似式を得ることができ、純抵抗を精度良く測定することのできるバッテリの純抵抗測定方法を提供することができる。
【０１３２】
上述した請求項７記載の発明によれば、濃度分極成分による電圧降下を除いた第２の二次修正近似式を簡単に求めることができるので、面倒な処理なしに純抵抗を測定することのできるバッテリの純抵抗測定方法を提供することができる。
【０１３３】
上述した請求項８記載の発明によれば、第１及び第２の修正近似式が共に二次式であるとき、ピーク値での微分値の中間の値を求める単純な計算によって純抵抗を測定することができるバッテリの純抵抗測定方法を提供することができる。
【０１３４】
上述した請求項９記載の発明によれば、元々濃度分極成分を含まない０点を利用して二次式の第２の修正近似式を求めているので、濃度分極成分を除く近似式を求めるための処理が少なくて良いバッテリの純抵抗測定方法を提供することができる。
【０１３５】
上述した請求項１０記載の発明によれば、中間の値を求めるために第２の修正近似式の傾きを使用しているので、中間の値を求めるための処理が簡単になるバッテリの純抵抗測定方法を提供することができる。
【０１３６】
上述した請求項１１記載の発明によれば、想定放電電流が０からピーク値に達するまでに生じる濃度分極成分による電圧降下を知り、濃度分極成分による電圧降下を除いたピーク値に対応する電圧値を求めているので、精度良く濃度分極成分を除いた第１の修正近似式を得ることができ、純抵抗を精度良く測定することのできるバッテリの純抵抗測定方法を提供することができる。
【０１３７】
上述した請求項１２記載の発明によれば、請求項１１記載の発明同様に、総濃度分極成分に占める想定放電電流が０からピーク値に達するまでに生じる濃度分極成分による電圧降下を知り、濃度分極成分による電圧降下を除いたピーク値に対応する電圧値を求めているので、精度良く濃度分極成分を除いた第１の修正近似式を得ることができ、しかも、第１及び第２の近似式が分かるだけで電流時間積を求めなくてもよいので、その分電流時間積と濃度分極の発生の対応関係に影響されることなく、かつ、面倒な処理を必要とすることがなくなり、簡単にかつ精度良く純抵抗を測定することのできるバッテリの純抵抗測定方法を提供することができる。
【０１３８】
上述した請求項１３記載の発明によれば、濃度分極の発生を伴わない短時間にピーク値まで単調増加する放電電流が流れるものである場合、純抵抗を測定するための処理が簡単になるだけでなく、近似式も簡単に求めることができるバッテリの純抵抗測定方法を提供することができる。
【図面の簡単な説明】
【図１】本発明のバッテリの純抵抗測定装置の基本構成を示すブロック図である。
【図２】本発明のバッテリの電流−電圧特性測定方法を用いて純抵抗を測定するバッテリの純抵抗測定方法を適用した本発明の一実施形態に係るバッテリの純抵抗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】スタータモータ駆動開始時の突入電流を伴う放電電流の一例を示すグラフである。
【図４】二次近似式で表したＩ−Ｖ特性の一例を示すグラフである。
【図５】増加方向の近似式から濃度分極成分の除き方の一例を説明するためのグラフである。
【図６】減少方向の近似式から濃度分極成分の除き方の一例を説明するためのグラフである。
【図７】増加方向を一次近似式で表したＩ−Ｖ特性の一例を示すグラフである。
【図８】第１の所定値からピーク値に達するまでの測定データと、ピーク値から第２の所定値までの測定データを使用して近似式を求めた場合の、突入電流が流れている総時間と、単調増加期間及び単調減少期間の時間の求め方を説明するためのグラフである。
【図９】減少方向の近似式から濃度分極成分の除き方の他の例を説明するためのグラフである。
【図１０】減少方向の近似式から濃度分極成分の除き方の別の例を説明するためのグラフである。
【図１１】図２中のマイコンが純抵抗測定のため予め定めたプログラムに従って行う処理を示すフローチャートである。
【図１２】式（１）及び（２）の差を取ることによって得た差の式に基づいて、ピーク電流値である点、並びに、任意の点の濃度分極成分の求め方を説明するためのグラフである。
【図１３】放電に伴う端子電圧の電圧降下の内訳を一般的に示すＩ−Ｖ特性を示すグラフである。
【図１４】従来のバッテリの純抵抗の測定の仕方を説明するためのグラフである。
【符号の説明】
２３ａ−１ 電流・電圧測定手段（ＣＰＵ）
２３ａ−２ 近似式算出手段（ＣＰＵ）
２３ａ−３ 演算手段（ＣＰＵ）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery current-voltage characteristic measuring method for supplying power to a load, and a battery pure resistance measuring method and apparatus for measuring a battery pure resistance using the current-voltage characteristics measured by this method. In particular, when power is supplied to a large current load, the current of the battery that measures the current-voltage characteristic indicating the relationship between the discharge current of the battery when the inrush current flows through the load at the start and the corresponding terminal voltage The present invention relates to a voltage characteristic measuring method and a battery pure resistance measuring method and apparatus.
[0002]
[Prior art]
In general, a battery can be used repeatedly within the range of its charge capacity by performing charging that covers the discharge current, but of course, when an unexpected situation such as overdischarge or insufficient electrolyte occurs. Even if these situations do not occur, the dischargeable capacity, which is the amount of power that can be supplied to the load by discharge, rapidly decreases when used over a long period of time and changes over time. For this reason, if the battery is an on-board battery, for example, if the dischargeable capacity is reduced due to aging, the starter motor is started after the engine stops even if the discharge exceeding the charge occurs for a short period of time. This can lead to a situation where the engine cannot be restarted.
[0003]
Incidentally, it is known that when a new product is compared with a battery that has changed over time, the net resistance of the battery that has changed over time compared to a new product is increased. Therefore, it is considered to measure the pure resistance of the battery as a guide for battery replacement at the time of periodic inspection of the vehicle. This can be used to determine the degree of deterioration and to estimate the open circuit voltage of the battery by knowing the pure resistance and considering the ratio between the pure resistance and the polarization resistance component.
[0004]
Generally, when current is discharged from a battery, a drop occurs in the terminal voltage of the battery. The voltage drop is due to the internal impedance (synthetic resistance) of the battery, but IR loss (pure resistance, ie, voltage drop due to ohmic resistance) due to the structure of the battery and polarization resistance due to chemical reaction. It can be divided into voltage drops due to components (activation polarization, concentration polarization). When the current-voltage (IV) characteristics are obtained, as shown in FIG. 13, the voltage drop due to IR loss does not change if the battery state is the same, but the voltage drop due to the polarization resistance component is large in current. And the time of current discharge.
[0005]
It is considered that only the pure resistance obtained by separating the polarization resistance component from the IV characteristic including the polarization resistance component is measured to estimate various states of the battery.
[0006]
Conventionally, in a measuring instrument generally used for measuring the pure resistance of a battery, when the battery is in a static state, that is, there is no voltage rise or voltage drop such as polarization in the electrolyte due to charging and discharging. When in equilibrium, the battery's pure resistance is measured.
[0007]
As an example, a voltage and current that change within a certain period of time, for example, about 1 μs, in a state in which alternating current having a frequency of about 1 kHz to 100 kHz is applied to the battery to repeatedly charge and discharge, and neither polarization of charge nor discharge accumulates. There is a method for obtaining the pure resistance from the relationship.
[0008]
As shown in FIG. 14, after stopping the discharge, the phenomenon that the voltage suddenly recovers and then gradually recovers is captured, and the rapid voltage recovery within a certain time Δt is only the component due to the pure resistance R. The subsequent gradual change is considered to be caused by components (capacitance and inductance components) including other elements including polarization other than pure resistance, and within a short time of each application cycle of alternating current with a frequency of about 1 kHz to 100 kHz. It is intended to measure pure resistance by capturing changes in voltage and current.
[0009]
However, the above-described method cannot be applied to a battery in a situation that exists only when the static state is limited.
[0010]
Therefore, at the start of power supply to the large current load, the battery discharge current and the corresponding period are increased and decreased during the inrush current that monotonously increases to the peak value flowing through the load and monotonously decreases from the peak value to the predetermined value. Two approximate expressions for the current-voltage characteristic indicating the relationship with the terminal voltage are obtained, and various states of the battery are estimated using these two approximate expressions. It is considered to estimate the pure resistance of the battery.
[0011]
[Problems to be solved by the invention]
However, when the battery is mounted, for example, in a vehicle, it is actually the case that power is already supplied to some load before power is supplied to the large current load. It does not begin to flow from 0, and at the end of the inrush current, the discharge current does not become 0, but ends when it becomes a steady current that continues to supply power to the load.
[0012]
Therefore, experimentally, an inrush current that monotonously increases from 0 and reaches a peak value and decreases monotonically from the peak value to 0 can be generated by program processing. No current flows. Therefore, in the battery mounted as described above, it is difficult to obtain an approximate expression of the discharge current-terminal voltage characteristics of the battery only for the inrush current that flows at the start of power supply to the large current load. For this reason, unless some measures are taken, inaccurate characteristics including currents other than inrush currents may occur, which may affect what is obtained using an approximate expression of current-voltage characteristics, for example, the accuracy of pure resistance. .
[0013]
Therefore, in view of the above-described situation, the present invention provides a current − indicating the relationship between the discharge current of the battery and the corresponding terminal voltage when an inrush current flows through the load at the start of power supply to the large current load. It is an object of the present invention to provide a battery current-voltage characteristic measurement method capable of measuring voltage characteristics by more accurately reflecting inrush current and corresponding terminal voltage.
[0014]
The present invention also provides a battery using a current-voltage characteristic indicating a relationship between a discharge current of a battery and a corresponding terminal voltage when an inrush current flows through the load when power is supplied to the large current load. It is an object of the present invention to provide a battery pure resistance measuring method and apparatus capable of measuring the pure resistance of the battery with higher accuracy.
[0015]
[Means for Solving the Problems]
  Claims to achieve the objectItem 1InvoiceItem 13The present invention described herein is a method for measuring a pure resistance of a battery,Item 14The present invention described herein relates to a battery pure resistance measuring device.
[0016]
  In order to solve the above-mentioned problem, the invention according to claim 1 isBaMonitor the battery ’s discharge current,Inrush current flows to the load when power supply to the load is startedWhen the discharge current increases beyond a predetermined first predetermined value, periodically measure the discharge current of the battery and the terminal voltage corresponding to the discharge current,
  The correlation between the measured discharge current and the terminal voltage is determined in advance from the first approximate expression of the current-voltage characteristic with respect to the discharge current monotonically increasing from the first predetermined value to the peak value and the peak value. A second approximate expression of current-voltage characteristics for a discharge current that monotonously decreases to a second predetermined value is obtained.,
When the obtained first and second approximate expressions include a voltage drop due to a concentration polarization component, a unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop Find the middle value of the two terminal voltage changes per hit,
The obtained intermediate value is measured as the value of the pure resistance of the battery.
Method for measuring the pure resistance of a batteryExist.
[0017]
According to the above-described procedure of claim 1, when the discharge current of the battery flowing along with the power supply to the load increases beyond a first predetermined value, the battery discharge current and the discharge current are The corresponding terminal voltage is measured periodically, and the first of the current-voltage characteristics with respect to the discharge current monotonically increasing from the first predetermined value to the peak value, showing the correlation between the measured discharge current and the terminal voltage. And the second approximate expression of the current-voltage characteristic with respect to the discharge current that monotonously decreases from the peak value to the predetermined second predetermined value, the predetermined first predetermined value and the second approximate expression are obtained. By setting the predetermined value to be equal to or greater than the start value and end value of the inrush current that reaches a certain peak value, from the start point of the increase period of the inrush current that suddenly reaches the peak value and decreases rapidly Discharge power up to peak value The first approximate expression is based on the measurement data of the terminal voltage and the second approximate expression is based on the measurement data of the discharge current and the terminal voltage from the peak value to the end point of the decrease period without taking in the measurement data other than the inrush current. , Respectively.
[0019]
  AndWhen the first and second approximate expressions obtained without including measurement data other than the inrush current include a voltage drop due to the concentration polarization component, the voltage drop is excluded from the first and second approximate expressions. Points that correspond to the peak values of both approximate expressions excluding the voltage drop due to the concentration polarization component, focusing on the peak value that is common to the increasing direction and decreasing direction after making the approximate expression of resistance and activation polarization only An intermediate value of two terminal voltage changes per unit current change is obtained, and the obtained intermediate value is measured as the value of the pure resistance of the battery.
[0020]
Therefore, the battery's net resistance can be measured simply by measuring the battery's discharge current and terminal voltage when power is supplied to the load under normal vehicle conditions and processing the data obtained as a result of this measurement. Can do.
[0021]
  ClaimItem 2The claimed invention is claimed.Item 1In the method for measuring the pure resistance of the battery, the discharge current and the terminal voltage are measured each time the discharge current and the terminal voltage are measured during a period in which the discharge current monotonously increases to the peak value exceeding the first predetermined value. The calculation for obtaining the first approximate expression based on the voltage is sequentially performed, and the first approximate expression is obtained for the discharge current whose peak value has increased beyond a predetermined third predetermined value. In order to obtain the second approximate expression based on the discharge current and the terminal voltage every time the discharge current and the terminal voltage are measured during a period in which the discharge current monotonously decreases from the peak value to the second predetermined value. There is a battery pure resistance measuring method characterized by sequentially performing the above operations.
[0022]
  Claim mentioned aboveItem 2According to the described procedure, every time the discharge current and the terminal voltage are measured during the period in which the discharge current monotonously increases to the peak value exceeding the first predetermined value, the first value is determined based on the discharge current and the terminal voltage. The calculation for obtaining the approximate expression is sequentially performed, and after the first approximate expression is obtained for the discharge current whose peak value has increased beyond a predetermined third predetermined value, the discharge current is calculated from the peak value to the second predetermined value. Every time the discharge current and the terminal voltage are measured during the monotonically decreasing value, the calculation for obtaining the second approximate expression is sequentially performed based on the discharge current and the terminal voltage, so the discharge current and the terminal voltage are measured. However, when the approximate expression can be calculated in real time and the peak value does not exceed the predetermined third predetermined value, the approximate expression is stopped midway as it is not measurement data effective for measuring the pure resistance. be able to.
[0023]
  ClaimItem 3The claimed invention is claimed.Item 1In the method for measuring a pure resistance of a battery, the intermediate value is calculated as 2 per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. The present invention resides in a method for measuring a pure resistance of a battery, which is obtained by averaging the values of two terminal voltage changes.
[0024]
  Claim mentioned aboveItem 3According to the described procedure, the value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component is obtained as an intermediate value. Since it is obtained by averaging, if the change in activation polarization at the point corresponding to the peak value becomes equal, the differential value at the point corresponding to the peak value of the first and second approximate expressions is added. By dividing by 2, the pure resistance of the battery can be measured.
[0025]
  ClaimItem 4The claimed invention is claimed.Item 1In the method for measuring a pure resistance of a battery, the intermediate value is calculated as 2 per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Assuming that the monotonically increasing discharge current is increased from 0 and the monotonically decreasing discharge current is reduced to 0, the assumed monotonically increasing ratio of the total time during which the assumed discharge current flows is assumed to be one terminal voltage change value. The present invention resides in a method for measuring a pure resistance of a battery, which is obtained by multiplying a period and a time ratio of the assumed monotonic decrease period and multiplying them.
[0026]
  Claim mentioned aboveItem 4According to the procedure described, the intermediate value is changed to two terminal voltage change values per unit current change at a point corresponding to the peak values of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. The activation polarization and the concentration polarization affect each other because they are calculated by multiplying the ratio of the time of the assumed monotonically increasing period and the assumed monotonically decreasing period to the total time during which the assumed discharge current flows. It is possible to obtain an intermediate value in consideration of mutual contact and measure the value as the pure resistance of the battery.
[0027]
  ClaimItem 5The claimed invention is claimed.1-4In the battery pure resistance measurement method according to any one of the above, when the first and second approximate expressions are quadratic expressions, the concentration is calculated from the first and second approximate expressions when obtaining the intermediate value. First and second modified approximate expressions excluding a voltage drop due to polarization components are obtained, and two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second modified approximate expressions. The present invention resides in a method for measuring a pure resistance of a battery characterized in that a value is obtained.
[0028]
  Claim mentioned aboveItem 5According to the procedure described above, when the first and second approximate expressions are quadratic expressions, the first value obtained by removing the voltage drop due to the concentration polarization component from the first and second approximate expressions is used to obtain an intermediate value. And the second modified approximate expression are obtained, and the values of two terminal voltage changes per unit current change at the point corresponding to the peak value of the first and second modified approximate expressions are obtained. Pure resistance can be measured by obtaining an intermediate value using the slope when the equation becomes a linear equation and the differential value at the peak value when the equation becomes a quadratic equation.
[0029]
  The invention described in claim 6Item 1In the method for measuring the pure resistance of the battery,The intermediate value is changed to the value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Time of the assumed monotonically increasing period and the assumed monotonically decreasing period in the total time during which the assumed discharge current flows when it is assumed that the increasing discharge current increases from 0 and the monotonically decreasing discharge current has decreased to 0 When the first and second approximate expressions are quadratic expressions, the concentration polarization is calculated from the first and second approximate expressions when the intermediate value is determined. First and second modified approximate expressions excluding voltage drop due to components are obtained, and two terminal voltage change values per unit current change at a point corresponding to the peak value of the first and second modified approximate expressions SeekingA difference in terminal voltage of the battery at a point where the discharge current is zero in the first and second approximate expressions is obtained, and the difference is a period in which the assumed discharge current increases from 0 to a peak value and decreases from a peak value to 0 The voltage drop due to the concentration polarization component occurring until the assumed discharge current occupying the total concentration polarization component reaches a peak value from 0 is obtained, and the obtained voltage drop is A secondary expression in which a secondary coefficient is determined by substituting a value obtained by removing a voltage value corresponding to a peak value into an expression in which a constant and a primary coefficient are equal to the first secondary approximation is used as the first modified approximation. It exists in the pure resistance measuring method of the battery characterized by calculating | requiring as a type | formula.
[0030]
  According to the procedure of claim 6 described above,The assumed discharge current flows to the value of the two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. It is calculated by multiplying the ratio of the time of the assumed monotonic increase period and the assumed monotonic decrease period to the total time, and adding them, so that the intermediate considering the mutual influence of activation polarization and concentration polarization Can be measured as the value of the pure resistance of the battery. When the first and second approximate expressions are quadratic expressions, the first and second approximate expressions are used to determine the intermediate value. First and second modified approximate expressions excluding the voltage drop due to the concentration polarization component are obtained, and two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second modified approximate expressions. Since we are looking for a value, , The slope when the corrected approximation formula is a linear equation, by obtaining an intermediate value by using a differential value at the peak value when the a quadratic equation, can be measured pure resistance,The difference between the terminal voltages of the battery at the point where the discharge current is zero in the first and second approximate expressions is due to the total concentration polarization component generated during the period when the assumed discharge current increases from 0 to the peak value and decreases from the peak value to 0. It is regarded as a voltage drop, a voltage drop due to the concentration polarization component that occurs until the assumed discharge current reaches the peak value from 0 is calculated for the total concentration polarization component, and the voltage value excluding the obtained voltage drop is the first two Since the quadratic expression obtained by substituting the quadratic approximate expression and the constant and the primary coefficient into the same formula to determine the quadratic coefficient is obtained as the first corrective approximate expression, the corrected approximate expression excluding the concentration polarization component is accurately obtained. Obtainable.
[0031]
  ClaimItem 7The claimed invention is claimed.Item 6In the battery pure resistance measurement method described above, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, two voltage values excluding the voltage drop due to the concentration polarization component between the peak value and 0 are obtained. A battery pure resistance measurement method is characterized in that a quadratic expression obtained by determining and using the three voltage values is determined as the second modified approximate expression.
[0032]
  Claim mentioned aboveItem 7According to the described procedure, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, two voltage values excluding the voltage drop due to the concentration polarization component between the peak value and 0 are obtained. Since the quadratic expression in which the coefficient is determined using the voltage value is obtained as the second correction approximate expression, the second quadratic correction approximate expression excluding the voltage drop due to the concentration polarization component can be easily obtained. .
[0033]
  ClaimItem 8The claimed invention is claimed.Item 7In the method for measuring the pure resistance of a battery, the differential value at the peak value of the first and second modified approximate equations is used to obtain the intermediate value. Exist.
[0034]
  Claim mentioned aboveItem 8According to the described procedure, when both the first and second modified approximate expressions are quadratic expressions, it is only necessary to obtain an intermediate value of the differential value at the peak value, so that the pure resistance is measured by a simple calculation. can do.
[0035]
  ClaimItem 9The claimed invention is claimed.Item 6In the battery pure resistance measurement method described above, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the voltage drop due to the concentration polarization component at the zero point and an intermediate point between the peak value and 0 is excluded. In the battery pure resistance measurement method, two voltage values are obtained, and a quadratic expression in which a coefficient is determined using the three voltage values is obtained as the second modified approximate expression.
[0036]
  Claim mentioned aboveItem 9According to the procedure described above, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, two voltage values excluding the voltage drop due to the concentration polarization component at the zero point and between the peak value and zero The quadratic expression in which the coefficient is determined using three voltage values is obtained as the second modified approximate expression, and the zero point that originally does not include the concentration polarization component is used. It is possible to reduce processing for obtaining an approximate expression to be excluded.
[0037]
  ClaimItem 10The claimed invention is claimed.Item 6In the method for measuring a pure resistance of a battery, a voltage value excluding a voltage drop due to a concentration polarization component at an intermediate point between the peak value and 0 other than a voltage value excluding a voltage drop due to the concentration polarization component at the peak value And a linear expression determined by connecting the two points is obtained as the second modified approximate expression, and the slope of the second modified approximate expression is used to obtain the intermediate value. The pure resistance measurement method.
[0038]
  Claim mentioned aboveItem 10According to the procedure described above, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the voltage value excluding the voltage drop due to the concentration polarization component at the midpoint between the peak value and 0 is obtained. Since the linear expression determined by connecting the points is obtained as the second modified approximate expression and the slope of the second modified approximate expression is used to obtain the intermediate value, the process for obtaining the intermediate value is simple. become.
[0039]
  ClaimItem 11The claimed invention is claimed.6-10In the method for measuring a pure resistance of a battery according to any one of the above, a voltage drop due to a concentration polarization component that occurs until the inrush current occupying the total concentration polarization component reaches a peak value from 0 is calculated using the first and second approximations. The difference between the terminal voltages of the battery at the point where the discharge current is 0 in the equation, the current from 0 to the peak value with respect to the current time product when the assumed discharge current increases from 0 to the peak value and decreases from the peak value to 0 The present invention resides in a method for measuring a pure resistance of a battery, which is obtained by multiplying by a ratio of time products.
[0040]
  Claims mentioned above11According to the procedure described, the battery at the point where the voltage drop due to the concentration polarization component occurring until the inrush current occupying the total concentration polarization component reaches the peak value from 0 is the discharge current 0 of the first and second approximate expressions. Is obtained by multiplying the difference in terminal voltage by the ratio of the current time product from 0 to the peak value to the current time product when the assumed discharge current increases from 0 to the peak value and decreases from the peak value to 0. The voltage drop due to the concentration polarization component that occurs until the assumed discharge current reaches the peak value from 0 can be known, and the voltage value corresponding to the peak value excluding the voltage drop due to the concentration polarization component can be obtained.
[0041]
  ClaimItem 12The claimed invention is claimed.6-10In the method for measuring the pure resistance of a battery according to any one of the above, the difference between the two expressions is obtained from the first and second approximate expressions, and the assumed discharge current occupying the total concentration polarization component is changed from 0 to a peak value. The voltage drop due to the concentration polarization component that occurs until the current value reaches 0 is calculated based on the difference between the terminal voltages of the battery at the point where the discharge current is 0 in the first and second approximate expressions based on the difference equation. The voltage value at the point that is the peak current value and the current value that is twice the peak current value with respect to the difference between the voltage value at the point and the voltage value at the point that is twice the current value of the peak current value The present invention resides in a method for measuring a pure resistance of a battery, which is obtained by multiplying a ratio of a difference from a value.
[0042]
  Claim mentioned aboveItem 12According to the described procedure, the difference between the two is obtained from the first and second approximate expressions, and the voltage drop due to the concentration polarization component that occurs until the assumed discharge current in the total concentration polarization component reaches the peak value from 0 The difference between the terminal voltage of the battery at the point where the discharge current is 0 in the first and second approximate expressions is twice the voltage value and the peak current value at the point where the current value is 0 based on the difference expression Is obtained by multiplying the ratio of the difference between the voltage value at the point that is the peak current value and the voltage value at the point that is twice the peak current value with respect to the difference from the voltage value at the point that is the current value. Therefore, even if the first and second approximate expressions are known and the current-time product is not obtained, the voltage drop due to the concentration polarization component occurring until the assumed discharge current reaches the peak value from 0 is known, and the voltage due to the concentration polarization component is obtained. The voltage value corresponding to the peak value excluding the drop can be obtained. .
[0043]
  ClaimItem 13The claimed invention is claimed.1-4In the method for measuring the pure resistance of a battery according to any one of the above, when the load flows a discharge current that monotonously increases to a peak value in a short time without occurrence of concentration polarization, the first approximate expression is A method for measuring a pure resistance of a battery, which is a linear expression and uses the slope of the first approximate expression to obtain the intermediate value.
[0044]
  Claim mentioned aboveItem 14According to the procedure described, when the load is a flow of a discharge current that monotonously increases to the peak value in a short time without the occurrence of concentration polarization, the first approximate expression is a linear expression, and the intermediate value is Since the slope of the first approximate expression is used for the determination, not only the process for determining the intermediate value is simplified, but also the approximate expression can be easily determined.
[0045]
  Claims made to solve the above problemsItem 14As shown in the basic configuration diagram of FIG. 1, the disclosed invention is a battery pure resistance measuring device for measuring the pure resistance of a battery mounted on a vehicle to supply electric power to a vehicle load. Current / voltage measuring means 23a- that monitors and periodically measures the discharge current of the battery and the terminal voltage corresponding to the discharge current when the discharge current increases beyond a predetermined first value. 1 and a first approximation of a current-voltage characteristic for a discharge current monotonically increasing from the first predetermined value to a peak value, showing a correlation between the discharge current measured by the current / voltage measuring means and the terminal voltage. Approximate expression calculating means 23a-2 for obtaining an expression and a second approximate expression of current-voltage characteristics with respect to a discharge current that monotonously decreases from the peak value to a predetermined second predetermined value, and the first and second The approximate expression When a voltage drop due to a polarization component is included, an intermediate value between two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop The battery pure resistance measuring apparatus includes a calculating means 23a-3 for obtaining, and measuring an intermediate value obtained by the computing means as a value of the pure resistance of the battery.
[0046]
  Claim mentioned aboveItem 14According to the configuration described above, when the discharge current of the battery flowing along with the power supply to the vehicle load increases beyond a predetermined first predetermined value, the discharge current of the battery and the terminal corresponding to the discharge current Current / voltage measuring means 23a-1 periodically measures the voltage, and shows the correlation between the measured discharge current and the terminal voltage. The current with respect to the discharge current monotonously increasing from the first predetermined value to the peak value. The approximate expression calculating unit 23a-2 obtains the first approximate expression of the voltage characteristic and the second approximate expression of the current-voltage characteristic with respect to the discharge current that monotonously decreases from the peak value to the predetermined second predetermined value.
[0047]
Therefore, by setting the first predetermined value and the second predetermined value that are determined in advance to be equal to or greater than the start value and the end value of the inrush current that reaches a certain peak value, the peak value is rapidly reached. The first approximate expression is based on the measurement data of the discharge current and the terminal voltage from the start point to the peak value of the increase period of the inrush current that rapidly decreases, and the measurement of the discharge current and the terminal voltage from the peak value to the end point of the decrease period. Based on the data, the second approximate expression can be obtained without taking in measurement data other than the inrush current.
[0048]
Next, when a voltage drop due to a concentration polarization component is included in the first and second approximate expressions, 2 per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding this voltage drop. The arithmetic means 23a-3 obtains an intermediate value between the two terminal voltage changes, and measures the obtained intermediate value as the value of the pure resistance of the battery.
[0049]
Therefore, the battery's net resistance can be measured simply by measuring the battery's discharge current and terminal voltage when power is supplied to the load under normal vehicle conditions and processing the data obtained as a result of this measurement. Can do.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
Before describing a battery pure resistance measuring apparatus according to the present invention with reference to FIG. 2, a method for measuring current-voltage characteristics of a battery according to the present invention together with the principle of the present invention with reference to FIGS. In addition, a battery pure resistance measurement method using current-voltage characteristics measured by this method will be described.
[0051]
By the way, as a vehicle load that is mounted with a battery and operates by being supplied with electric power from the battery, a 12V car, a 42V car, an EV car, and an HEV car require a large current such as a starter motor, a motor generator, and a traveling motor. Load is installed. For example, when a starter motor or a large current load similar thereto is turned on, a rush current flows through the load at an initial stage of driving, and then a steady current corresponding to the magnitude of the load flows. Incidentally, the inrush current is sometimes called a rush current.
[0052]
When a DC motor is used as the starter motor, the inrush current flowing through the field coil is, as shown in FIG. 3, compared with a steady current from approximately 0 within a short time of, for example, 3 milliseconds immediately after the start of driving. After monotonically increasing to a peak value many times larger, for example, 500 (A), the flow is such that it monotonously decreases from this peak value to a steady value corresponding to the magnitude of the load within a relatively short time. However, as is apparent from FIG. 3, before the starter motor is turned on, a discharge current for supplying power to a load other than the starter motor flows from the battery, and along with the cranking operation during engine startup. When the steady current increases or decreases and the engine starts, the discharge current is switched to the charging current as the generator generates power.
[0053]
Therefore, when the ignition switch is turned on and an inrush current flows through the starter motor, the battery discharge current and the corresponding terminal voltage are measured only during the inrush current flow, and the other discharge currents and By discarding the corresponding terminal voltage, it is possible to measure the discharge current (I) -terminal voltage (V) characteristic of the battery, which shows the change in the terminal voltage with respect to a sudden current change in a relatively wide range.
[0054]
Next, the principle of the method for measuring the pure resistance of the battery according to the present invention will be described in the case of performing a simulated discharge corresponding to the inrush current that flows when the starter motor is turned on. As a simulated discharge, the battery is discharged using an electronic load, increasing from 0 (A) to approximately 200 A over 0.25 seconds and decreasing from the peak value to 0 (A) over the same time. Measure the battery discharge current and terminal voltage at that time in a short fixed period, and plot the measurement data pair obtained by matching the discharge current on the horizontal axis and the terminal voltage on the vertical axis. Thus, the graph shown in FIG. 4 is obtained. The current-voltage characteristics at the time of increase and decrease of the discharge current shown in the graph of FIG. 4 can be approximated by the following quadratic equation using the least square method.
V = a1I²+ B1I + c1 (1)
V = a2I²+ B2I + c2 (2)
In the drawing, a curve of a quadratic approximate expression is also drawn.
[0055]
By the way, how to obtain an approximate expression by the least square method will be briefly described below. The least squares method is
Σεi²= Σ (aI²+ BI + c-V)²
(Ε: error, i: 1, 2, ... n)
Σεi in²Is a method for determining each approximation coefficient (here, a, b, c) and determining an approximate expression. In order to obtain the approximate expression coefficients a, b, c,
Σ (aI²+ BI + c-V)²
What is necessary is just to perform partial differentiation with the coefficient (a, b, c) which calculates | requires. The result is expressed by the following determinant.
[0056]
[Expression 1]

[0057]
Expressions for obtaining the coefficients of the approximate expression obtained by solving this matrix with respect to a, b, and c are as follows. Then, ΣI, ΣI obtained by calculation every time the discharge current I and the terminal voltage V are periodically measured by sampling.², ΣI^Three, ΣI^Four, ΣV, ΣV², ΣVI, ΣVI² If the calculation is performed based on this equation, each coefficient of the approximate equation can be obtained.
[0058]
[Expression 2]

[0059]
[Equation 3]

[0060]
[Expression 4]

[0061]
[Equation 5]

[0062]
In FIG. 4, since the voltage difference between the intercept of the approximate curve in the current increasing direction and the intercept of the approximate curve in the current decreasing direction is the voltage difference at 0 (A) when no current flows, the pure resistance and the activity This is considered to be a voltage drop only due to the concentration polarization component newly generated by the discharge, which does not include a voltage drop due to the polarization. Accordingly, if this voltage difference is Vpolc0, the concentration polarization at the current 0 (A) point, the concentration polarization Vpolc0 is obtained by multiplying the magnitude of the inrush current by the time when the current flows, that is, Ah (because it is a short time). , Hereinafter expressed as Asec).
[0063]
Next, a method for calculating the concentration polarization of the current peak value using the concentration polarization Vpolc0 at the current 0 (A) point will be described. Now, assuming that the concentration polarization of the current peak value is Vpolcp, Vpolcp is expressed by the following equation.
Vpolcp = [(Asec when current increases) / (Asec of the entire discharge)] × Vpolc0 (3)
Note that Asec of the entire discharge is expressed by the following equation.
Asec of overall discharge = (Asec when current increases + Asec when current decreases)
[0064]
The concentration polarization component Vpolcp at the peak value obtained as described above is added to the voltage at the peak value of Equation (1), and the concentration polarization component at the peak value is deleted as shown in FIG. If the voltage after removing the concentration polarization component at the peak value is V1, V1 is expressed by the following equation.
V1 = a1Ip²+ B1Ip + c1 + Vpolcp
Ip is the current value at the peak value.
[0065]
Next, using V1 obtained as described above, a voltage drop curve of only pure resistance and activation polarization as shown in FIG.
V = a3I²+ B3I + c3 (4)
[0066]
When attention is paid to the initial state of the characteristics represented by the equations (1) and (4), that is, the point where the current is 0 (A), the polarization in the initial state is equal, so c3 = c1. In addition, although the current increases rapidly from the initial state of the current increase, if the reaction of concentration polarization is slow and the reaction hardly progresses, the currents of the formulas (1) and (4) are points of 0 (A). Since the differential values of are equal, b3 = b1. Therefore, by substituting c3 = c1 and b3 = b1, equation (4) becomes
V = a3I²+ B1I + c1 (5)
And the unknown is only a3.
[0067]
Therefore, when the coordinates (Ip, V1) of the peak value of current increase are substituted into equation (5) and arranged for a3, the following equation is obtained.
a3 = (V1-b1Ip-c1) / Ip²
Therefore, the equation (4) of the voltage drop curve with only the pure resistance and the activated polarization component is determined by the equation (5).
[0068]
In general, since pure resistance is not caused by a chemical reaction, it is constant unless the state of charge (SOC), temperature, etc. of the battery changes, so it can be said that it is constant during one starter motor operation. On the other hand, the activation polarization resistance is a resistance caused by a chemical reaction at the time of delivery of ions and electrons. Therefore, the activation polarization resistance may interact with the concentration polarization, and the current increase curve of the activation polarization Since the current decrease curves do not completely coincide, it can be said that the equation (5) is a curve in the current increasing direction of the pure resistance and activation polarization excluding the concentration polarization component.
[0069]
Next, how to delete the concentration polarization component from the current decrease curve will be described below. The relational expression between the pure resistance and the activation polarization current decreasing direction can be obtained by the same method as the deletion of the concentration polarization at the current peak value. Two points other than the peak value are designated as point A and point B, and concentration polarizations VpolcA and VpolcB at each point are obtained as follows.
VpolcA = [(Asec from start of current increase to point A) / (Asec of the entire discharge)] × Vpolc0 (6)
VpolcB = [(Asec from the start of current increase to point B) / (Asec of the entire discharge)] × Vpolc0 (7)
[0070]
When two points from which the concentration polarization component is deleted in addition to the peak value are obtained by the above formulas (6) and (7), it is expressed by the following formula using the coordinates of these two points and the peak value. As shown in FIG. 6, a current decreasing direction curve of pure resistance and activation polarization is obtained.
V = a4I²+ B4I + c4 (8)
Note that the coefficients a4, b4, and c4 in Equation (8) solve a three-point simultaneous equation obtained by substituting the current values and voltage values of the two points A and B and the peak point into Equation (8), respectively. Can be determined.
[0071]
Next, how to calculate the pure resistance will be described. A pure resistance and activation polarization curve in which the concentration polarization component represented by the above equation (5) is deleted, and a pure resistance and activation polarization in which the concentration polarization component is also deleted and represented by the equation (8). Since the difference from the curve of the current decrease direction is due to the difference in the activation polarization component, a pure resistance is required except for the activation polarization component.
[0072]
By the way, paying attention to the peak values of both curves where the activation polarizations are equal to each other, the differential value R1 of the current increase and the differential value R2 of the current decrease at the peak value are obtained by the following equations.
R1 = 2 × a3 × Ip × b3 (10)
R2 = 2 × a4 × Ip × b4 (11)
The difference between the differential values R1 and R2 obtained by the above equation is based on the fact that one is the peak value in the increasing direction of the activation polarization while the other is the peak value in the decreasing direction. Then, as a simulated discharge corresponding to the inrush current, an electronic load is used that increases from 0 (A) to 200 A over 0.25 seconds and decreases from the peak value to 0 (A) over the same time. When the battery is used, it can be understood that the rate of change of both in the vicinity of the peak value is equal, and that there is a current-voltage characteristic due to a pure resistance in the middle of both, so add both differential values to 2 By dividing, the pure resistance R can be obtained by the following equation.
R = (R1 + R2) / 2 (12)
[0073]
The above describes the case where the battery is subjected to a simulated discharge corresponding to the inrush current using an electronic load. However, in the case of an actual vehicle, a DC motor is used as the starter motor as described above. The discharge current may flow before the inrush current flows through the field coil, and the current reaches a peak while the inrush current flows, and the cranking reaches half the peak current after reaching the peak. After the inrush current is finished, it is operated with a steady current, and unlike the case of the simulated discharge, the inrush current always starts from 0 (A) and does not end at 0 (A). In this way, in the actual vehicle, discharge currents of elements other than the inrush current flow, so when these are used to obtain the above approximate expression, an expression different from the approximate expression of only the inrush current is obtained and the pure resistance Therefore, it is difficult to accurately obtain the current value, and it is necessary to obtain an approximate expression using only the measurement data of the discharge current due to the inrush current.
[0074]
Therefore, an approximate expression of the current increase period is obtained using the measurement data until the discharge current increases beyond the predetermined first predetermined value IA and reaches the peak value Ip, and the predetermined value is determined from the peak value. An approximate expression of the current decrease period is obtained using measurement data until the value decreases to a predetermined value IB of 2. The first predetermined value IA is defined as a lower limit value that does not flow in the direction of current increase in a normal load, and the second predetermined value IB is defined as an upper limit value that flows in a normal load. That is, before the inrush current begins to flow and the cranking period, a phenomenon different from the period in which the inrush current flows occurs, so the battery discharge current and terminal voltage during this period are It is not used as data for determining the current-voltage characteristics in the current decreasing direction.
[0075]
Further, in the case of a DC motor having a field coil, the current increase direction is completed in a short time of 3 milliseconds (msec), and the current increase peak value is a rapid current change in which almost no concentration polarization occurs. In the current decreasing direction, a current flows for a longer time, for example, 150 msec than the current increasing direction, so that a large concentration polarization occurs even though the current decreases.
[0076]
In such a situation, in an actual vehicle with a DC motor having a field coil, as shown in FIG. 7, the current increasing direction can be approximated by a straight line connecting the current increasing start point and the peak value. Moreover, the occurrence of concentration polarization at the peak value 500 (A) can be approximated to 0 (A). In this case, for the current increasing direction, the slope of the approximate straight line in the current increasing direction is used as the differential value of the peak value.
[0077]
However, in such a case, it is not possible to simply add and average the slope of the approximate straight line in the current increasing direction and the slope of the tangent at the peak point of the quadratic approximate expression in the current decreasing direction. This is because in such a situation, the degree of occurrence of activation polarization is completely different up to and after the peak point, and the assumption that the rate of change of both in the vicinity of the peak value is not satisfied.
[0078]
In such a case, in determining the pure resistance, two terminal voltage change values per unit current change at a point corresponding to the peak values of the first and second approximate expressions excluding the voltage drop due to concentration polarization, That is, the slope may be added after multiplying the ratio of the time of the monotonically increasing period and the monotonically decreasing period in the total time during which the inrush current flows. That is, the total time is added after proportionally dividing the respective proportions by the time required for the monotonous increase and the monotonous decrease. By doing in this way, a pure resistance can be calculated considering that activation polarization and concentration polarization influence each other.
[0079]
However, in the case of the above-described actual vehicle, the inrush current does not start from 0 (A) and does not end at 0 (A). Therefore, the approximate expression uses the measurement data from the first predetermined value to the peak value, the peak The measurement data from the value to the second predetermined value must be used. Therefore, the ratio of the time of the monotonically increasing period and the monotonically decreasing period in the total time during which the inrush current flows cannot be simply obtained. Therefore, based on the measurement data from the first predetermined value IA to the peak value Ip and the measurement data from the peak value Ip to the second predetermined value IB, the total time during which the inrush current flows and the monotonic increase A method for obtaining the period and the time of the monotonically decreasing period will be described below with reference to FIG. 8 in which the protruding current-time characteristic is approximated to a triangle.
[0080]
As shown in FIG. 8, the first predetermined value IA, the peak value Ip, the second predetermined value IB, the first predetermined value IA to the peak value Ip, and the peak value Ip to the second predetermined value IB. Based on the times Ta and Tb obtained by multiplying the number of times of sampling up to the sampling interval, a current-time characteristic based on measurement data as shown by a dotted line can be drawn. The characteristic indicated by the dotted line is represented by a current 0 (A). The current-time characteristic approximated to a triangle is obtained by extending to the point. Then, the time Ta ′ from the point of the current 0 (A) to the peak value and the time Tb ′ from the peak value to the point of the current 0 (A) are determined as the times of the monotonically increasing period and the monotonically decreasing period by the following equations. It is possible to calculate the total time as the total time.
Ta '= Ip.Ta / (Ip-IA)
Tb '= Ip.Tb / (Ip-IB)
[0081]
In short, the activation polarization has a magnitude corresponding to the current value in principle, but it depends on the amount of concentration polarization at that time and does not occur in principle. If the concentration polarization is small, the activation polarization is small. The bigger it is, the bigger it becomes. In any case, the value between the two terminal voltage changes per unit current change at the point corresponding to the peak values of the two approximate expressions excluding the voltage drop due to the concentration polarization component is the value of the pure resistance of the battery. Can be measured.
[0082]
In recent vehicles, an AC motor requiring a three-phase input such as a DC brushless such as a magnet motor is increasingly used as a motor. In the case of such a motor, the inrush current does not reach the peak value in such a short time, it takes about 100 msec, and concentration polarization occurs in the direction of increasing current. As in the case of, the current change curve in the direction of current increase needs to be quadratic approximated.
[0083]
In addition, when approximating the current decreasing direction of the activation polarization, when the peak value and the other two points are determined, as shown in FIG. Can be simplified.
[0084]
Further, for example, when a point where concentration polarization is deleted is determined at a point corresponding to a current value of about ½ of the peak current, as shown in FIG. You may approximate. In this case, for the current decrease direction, the slope of the approximate straight line in the current decrease direction is used as the differential value of the peak value. However, the accurate pure resistance is the same as that using the quadratic curve. Desired.
[0085]
In short, the intermediate value of the two terminal voltage changes per unit current change at the point corresponding to the peak values of the two approximate expressions excluding the voltage drop due to the concentration polarization component is measured as the value of the pure resistance of the battery. be able to.
[0086]
Therefore, the pure resistance measurement method for a battery is concretely used when, for example, a starter motor is used as a load, in which an inrush current accompanied by the occurrence of concentration polarization flows in both an increasing discharge current and a decreasing discharge current. Explained.
[0087]
When the starter motor is started, an inrush current that monotonously increases beyond the first predetermined value and monotonously decreases from the peak value to the second predetermined value flows from the battery as a discharge current. Accordingly, the battery discharge current and the terminal voltage are sampled at a period of, for example, 100 microseconds (μsec), thereby monitoring the battery discharge current, and after the discharge current exceeds the first predetermined value. The discharge current and the terminal voltage are periodically measured, and a set of the battery discharge current and the terminal voltage can be obtained sequentially, and the peak value can be obtained from the measured value of the discharge current obtained by this sampling. A set of battery discharge current and terminal voltage can be sequentially obtained until the discharge current decreasing from the peak value becomes equal to or less than the second predetermined value.
[0088]
Each time a set of the battery discharge current and the terminal voltage is obtained in this way, the approximate expression V = a1I of the above equation (1) is obtained when the discharge current increases.²+ B1I + c1, the approximate expression V = a2I of the above equation (2) when decreasing²In order to obtain approximate equations by determining each coefficient of + b2I + c2, ΣI, ΣI², ΣI^Three, ΣI^Four, ΣV, ΣV² , ΣVI, ΣVI² ΣI, ΣI calculated based on the measured data of the monotonically increasing period and the monotonically decreasing period of the discharge current², ΣI^Three, ΣI^Four, ΣV, ΣV² , ΣVI, ΣVI² Is used to calculate the coefficients, and the current-voltage characteristics with respect to the increasing discharge current and the decreasing discharge current indicating the correlation between the terminal voltage and the discharge current are calculated by the least square method. Two quadratic approximations as shown in FIG. Next, a voltage drop due to the concentration polarization component is deleted from the two approximate equations, and a modified quadratic approximate equation not including the concentration polarization component is obtained.
[0089]
For this purpose, first, the voltage difference at the time of 0 (A) in which the currents of the approximate expressions (1) and (2) obtained as described above do not flow is expressed as a voltage drop due to the pure resistance and the activation polarization. Rather, it is determined to be due to concentration polarization. Further, using this voltage difference, the voltage drop due to the concentration polarization component at the current peak value in the approximate expression (1) of the current-voltage characteristic for the increasing discharge current is obtained. For this purpose, the concentration polarization uses the fact that it changes by the current-time product obtained by multiplying the magnitude of the current by the time when the current flows. As the time for obtaining the current-time product, Ta ′ and Tb ′ described above are used.
[0090]
Once the voltage drop due to the concentration polarization component at the current peak value in the approximate expression of the current-voltage characteristic for the increasing discharge current is found, then both the approximate expression that does not include the concentration polarization component and the approximate expression that includes the concentration polarization component are constant and linear. Assuming that the coefficients are equal, a secondary coefficient of an approximate expression not included is determined, and a secondary approximate expression (5) obtained by correcting the approximate expression of the current-voltage characteristic for the increasing discharge current is obtained.
[0091]
Next, an approximate expression that does not include a concentration polarization component is obtained from the approximate expression (2) for the current-voltage characteristics with respect to the decreasing discharge current. For this purpose, two points are obtained by deleting the concentration polarization component other than the peak value. At this time, the concentration polarization uses the fact that it changes by the current-time product obtained by multiplying the current magnitude by the time when the current flows. When two points from which the concentration polarization component is deleted in addition to the peak value are obtained, an approximate expression (2) of the current-voltage characteristic for the decreasing discharge current is obtained using the coordinates of the three points of the two points and the peak value. The quadratic approximate expression (8) corrected for) is obtained.
[0092]
A pure resistance from which the concentration polarization component represented by the above equation (5) is deleted and a modified quadratic approximate expression in the direction of current increase in activation polarization, and a pure resistance from which the concentration polarization component represented by equation (8) is deleted Since the modified quadratic approximation formula for the current decrease direction of the activation polarization is due to the difference in the activation polarization component, the pure resistance is obtained except for the activation polarization component. For this reason, paying attention to the peak values of both approximate equations, the difference between the differential value of the current increase and the differential value of the current decrease at the peak value is that one is the increasing direction of activation polarization, while the other is Although it is based on the decreasing direction, it is assumed that there is a current-voltage characteristic due to a pure resistance in the middle of the rate of change between the two near the peak value, and the total time during which the inrush current flows in both differential values ( The net resistance is obtained by multiplying the respective times Ta ′ and Tb ′ of the monotonically increasing period and the monotonically decreasing period of Ta ′ + Tb ′) and multiplying them.
[0093]
For example, assuming that the current increase time is 3 msec, the current decrease time is 100 msec, the differential value of the current increase at the peak value is Rpolk1, and the differential value of the current decrease is Rpolk2, the pure resistance R can be calculated as follows. it can.
R = Rpolk1 × 100/103 + Rpolk2 × 3/103
[0094]
A specific embodiment of the apparatus that enables the above-described method for measuring the pure resistance of the battery according to the present invention will be described below with reference to FIG.
[0095]
FIG. 2 is an explanatory diagram partially showing a schematic configuration of an on-vehicle battery pure resistance measuring apparatus according to an embodiment of the present invention to which the battery pure resistance measuring method of the present invention is applied. The on-vehicle battery pure resistance measuring device of this embodiment shown is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3.
[0096]
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.
[0097]
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.
[0098]
In the case of a vehicle, when an ignition switch or an accessory (ACC) switch is turned on, a battery discharge current flows along with power supply to a load that is on at that time. Further, the motor generator 5 is used as a starter 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 inrush current flows. 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 is turned on with the release of the operation of the ignition key (not shown). Along with this, the discharge current flowing from the battery 13 shifts to a steady current according to the load.
[0099]
Returning to the description of the configuration, the on-vehicle battery pure resistance measuring device 1 of the present embodiment is configured such that the discharge current I of the battery 13 with respect to the electrical components such as the motor generator 5 functioning as a motor for assist travel and a starter motor, A current sensor 15 that detects a charging current for the battery 13 from the motor generator 5 that functions as a generator, and a voltage sensor 17 that has a resistance value of about 1 M ohm connected in parallel to the battery 13 and detects the terminal voltage V of the battery 13. And.
[0100]
Further, in the in-vehicle battery pure resistance measuring apparatus 1 according to this embodiment, the outputs of the current sensor 15 and the voltage sensor 17 described above are after A / D conversion in an interface circuit (hereinafter abbreviated as “I / F”) 21. A microcomputer (hereinafter abbreviated as “microcomputer”) 23 is further provided.
[0101]
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 in addition to the RAM 23b and the ROM 23c. A switch, an ignition switch, an accessory switch, a switch of an electrical component (load) other than the motor generator 5 are further connected.
[0102]
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.
[0103]
Note that 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 high speed in a short cycle, and are taken into the CPU 23a of the microcomputer 23 via the I / F 21. The voltage value is used for various processes.
[0104]
Next, processing performed by the CPU 23a according to the control program stored in the ROM 23c will be described with reference to the flowchart of FIG.
[0105]
When the ignition (IG) switch is turned on and the microcomputer 23 is activated by receiving power from the battery 13 and the program is started, the CPU 23a starts sampling the discharge current and the terminal voltage at a sampling period of 100 μsec (step S1). A process for reading the measurement data via the I / F 21 with the A / D conversion value 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 as a pair is executed. The discharge current is monitored to exceed a predetermined first value IA. When the discharge current exceeds the first predetermined value IA, it is determined that the inrush current has started to flow, and processing for obtaining an approximate expression is entered. Depending on whether or not the discharge current has reached the peak value, the process for obtaining the approximate expression is switched (step S3). Note that whether or not the discharge current has reached the peak value is determined during the later-described process for obtaining an approximate expression of the period during which the protruding current is increasing.
[0106]
When the peak current has not been reached (when the determination in step S3 is N), the sampling value is compared with the previous sampling value (step S4), and as a result of the comparison, the sampling value has increased from the previous sampling value When the determination in step S4 is Y, each Σ term is calculated based on the sampled discharge current and terminal voltage to obtain an approximate expression when the current increases (step S5). Further, when the result of comparison shows that the sampling value has decreased from the previous sampling value (when the determination in step S4 is N), it is monitored whether or not the sampling value has decreased continuously n times (step S6). When it has decreased continuously n times (when the determination in step S6 is Y), it is determined that the discharge current has started to decrease from the peak value (step S7). When not decreasing n times continuously (when the determination in step S6 is N), the calculation of each Σ term for obtaining an approximate expression at the time of current decrease based on the sampled discharge current and terminal voltage Is performed (step S8).
[0107]
When each Σ term is calculated when the current increases (step S5), when there is a calculation result for each Σ term when the current is calculated at step S8 (when step S9 is Y). The result is added to each Σ term when the current increases (step S10) and each Σ term when the current decreases is cleared (step S11). This is a process for reflecting in the approximate expression as measurement data when the sampling current value temporarily decreases during the current increase period of the inrush current but does not reach the peak value. In addition, since the calculation of step S8 is performed when the sampling value is continuously decreased n times, the current decrease is performed based on the sampling value during the period not continuously decreased n times before the peak value is determined. This is for performing the calculation of each Σ term in advance to obtain the approximate expression of time.
[0108]
After the peak current is determined (when step S3 is Y), each Σ term is calculated to obtain an approximate expression when the current decreases based on the sampled discharge current and terminal voltage (step S3). S12). At this time, since the calculation result of each Σ term at the time of the current decrease calculated in step S8 remains, the calculation is performed following the calculation result of step S8. Thereafter, it is monitored whether or not the discharge current decreases beyond a predetermined second predetermined value IB (step S13), and until the discharge current decreases beyond the second predetermined value IB (step S13 is Y Steps S1 to S3 and Steps S12 and S13 are repeatedly executed, and the calculation of each Σ term when the current decreases is repeated. When the discharge current decreases beyond the second predetermined value IB (when step S13 is Y), it is determined that the inrush current has ended, the processing for obtaining the approximate expression is ended, and the calculation is performed in step S5. The approximate expression at the time of current increase is obtained by using each Σ term at the time of current increase, and the approximate expression at the time of current decrease is obtained by using each Σ term at the time of current decrease calculated in step S12.
[0109]
Although not clearly shown in the flowchart, it is naturally necessary to determine whether or not the obtained approximate expression is valid, and this determination is performed for each coefficient for determining each coefficient of the approximate expression. This can be done by comparing the correlation coefficient between the current increase and the current decrease, which can be obtained using the calculation result of the Σ term, and the magnitude of the peak current with a predetermined value.
In particular, an error factor can be removed by providing the first and second predetermined values.
[0110]
In the calculation process for executing the calculation process for obtaining the pure resistance of the battery from the obtained quadratic approximate expression, when the voltage drop due to the concentration polarization component is included in the quadratic expression, the corrected second excluding this voltage drop is used. A modified quadratic approximate expression calculation process for obtaining the next approximate expression is performed, and an arithmetic process for determining the pure resistance of the battery is executed using the modified quadratic approximate expression. In this case, the increasing discharge current Then, after calculating the differential value at the peak value of the two modified quadratic approximate expressions of the current-voltage characteristics with respect to the decreasing discharge current, an operation for obtaining the intermediate value of the two differential values as the pure resistance of the battery is performed. The obtained pure resistance of the battery is stored and stored in the data area of the RAM 23b for use for various purposes.
[0111]
There are two methods for obtaining an intermediate value of the differential value depending on the flow shape of the inrush current.
When the time in the increase direction of the inrush current is substantially equal to the time in the decrease direction, a calculation is performed to obtain the addition average value of the two differential values as a pure resistance.
On the other hand, when the time in the increase direction and the time in the decrease direction of the inrush current are greatly different, the discharge current of the discharge current is changed to the differential value at the peak value of the modified second-order approximate expression of the current-voltage characteristic for the increasing discharge current Multiplying the ratio of the increasing discharge current flow time to the total time and the differential value at the peak value of the two modified quadratic approximations of the current-voltage characteristics for the decreasing discharge current, the total discharge current An operation is performed to obtain an added value obtained by adding the product of the ratio of the time during which the decreasing discharge current flows in the time as the pure resistance.
When the pure resistance is obtained by any method, the pure resistance of the battery is obtained as an intermediate value between the two differential values.
[0112]
In the example shown in the flowchart of FIG. 11, the first and second approximate expressions are both quadratic approximate expressions. However, when the first approximate expression is the primary approximate expression, the process for obtaining the corrected approximate expression is as follows. Naturally it becomes unnecessary. In this case, the slope of the linear expression is used instead of the differential value.
[0113]
Further, in the on-vehicle battery pure resistance measuring apparatus 1 of the present embodiment, step S5 in the flowchart is processing for the current / voltage measuring means in the claims, and step S12 corresponds to the approximate expression calculating means in the claims. Step S13 is processing corresponding to the calculation means in the claims.
[0114]
Next, the operation (action) of the in-vehicle battery pure resistance measuring apparatus 1 of the present embodiment configured as described above will be described.
[0115]
First, in a state where the battery 13 is discharging as the starter motor starts driving, an inrush current that monotonously increases beyond the first predetermined value and monotonously decreases from the peak value to the second predetermined value flows to the starter motor. The battery terminal voltage and the discharge current are measured periodically.
[0116]
Further, in the in-vehicle battery pure resistance measuring apparatus 1 according to the present embodiment, whether or not the measurement data is appropriate for obtaining a quadratic approximate curve equation of the current-voltage characteristic by applying the least square method. Is determined, and when it is determined that it is not appropriate, the processing is stopped halfway.
[0117]
In the above-described embodiment, the present invention is implemented by paying attention only to the inrush current included in the discharge current when the starter motor starts to be driven. However, the drive is performed in the same manner as the starter motor having a different size. The present invention can be equally applied to loads other than the starter motor through which an inrush current flows at the start.
[0118]
In the above-described embodiment, the difference between the terminal voltage of the battery at the point where the discharge current is 0 (A) in the first and second approximate expressions is increased from 0 to the peak value of the inrush current. A voltage drop due to the total concentration polarization component occurring during the period reduced in A) is regarded as a voltage drop due to the concentration polarization component that occurs until the inrush current in the total concentration polarization component reaches the peak value from 0 (A). The current time when the inrush current increases from 0 to the peak value and decreases from the peak value to 0 (A) due to the difference in the battery terminal voltage at the point where the discharge current is 0 (A) in the first and second approximate expressions. Although it is obtained by multiplying the ratio of the current time product from 0 (A) to the peak value with respect to the product, it can be obtained by other methods, and the method will be described below.
[0119]
In the first place, if the difference between the first approximate expression and the second approximate expression is the difference in the concentration polarization component, the current value 0 is obtained from the peak current at which the concentration polarization component becomes equal by taking the difference expression between the two expressions. The difference between the concentration polarizations up to (A) can be made significant, and a change in the concentration polarization component from the current value 0 to the peak current value can be predicted based on the difference formula.
[0120]
Taking the difference between the above formulas (1) and (2),
ΔV = V = (a1-a2) I²+ (B1-b2) I + (c1-c2) (21)
Ask for. When this is plotted, as shown in FIG. 12, the concentration polarization component becomes 0 at the point of the peak current value, and a curve showing the change of only the concentration polarization component up to the current value 0 is drawn. Then, by extending the curve drawn by the equation (21) to a point having a value twice the peak current value as indicated by a dotted line, the state of change in the concentration polarization component from the current value 0 to the peak current value is shown. Predict. That is, the relative change in the concentration polarization between current increase and current decrease is predicted based on the difference formula.
[0121]
The difference equation expresses the state of occurrence change between the concentration polarization from the current value 0 to the peak current and the concentration polarization from the peak current to the current value 0, condensed between the current value 0 and the peak current. Therefore, by extending the curve represented by this equation to twice the discharge current, it is assumed that the concentration polarization changes when the current flows as current value 0-peak value-current value. Will be able to. Therefore, the present invention can be effectively applied even when the proportional relationship between the current time product and the concentration polarization is disturbed and the accuracy is deteriorated when the concentration polarization at an arbitrary point is estimated using the current time product.
[0122]
Therefore, the voltage value VP and the peak current value at the point that is the peak current value with respect to the difference (V2P−V0) between the voltage value V0 at the point where the current value is 0 and the voltage value V2P at the point that is the double peak current value. The ratio of the difference (V2P-VP) from the voltage value at the point that is twice the current value is obtained, and this is the current difference that is the voltage difference between the intercept of the approximate curve in the current increasing direction and the intercept of the approximate curve in the current decreasing direction. (A) The concentration polarization component at the point that is the peak current value is predicted by multiplying the concentration polarization Vpolc0 at the point. The concentration polarization component at the point of the predicted peak current value can be handled in the same way as the above-described Vpolcp, and a voltage drop curve with only pure resistance and activation polarization can be obtained.
[0123]
When deleting the concentration polarization component from the current decrease curve, it is possible to delete the concentration polarization component at the current peak value by the same method. That is, the voltage value at two points other than the peak value is obtained by the equation (21), and the difference between the voltage value V0 at the point where the current value is 0 (A) and the voltage value V2P at the point where the peak current value is twice is obtained. The ratio of the difference between the voltage value at two points other than the peak value and the voltage value at the point that is twice the current value of the peak current value is obtained, and this is calculated as the intercept of the approximate curve in the current increasing direction and the approximate curve in the current decreasing direction. The concentration polarization component at each point is predicted by multiplying the concentration polarization Vpolc0 at the current 0 (A) point, which is the voltage difference between the intercepts. By using these two predicted concentration polarization components together with the concentration polarization component of the peak current value, it is possible to obtain a voltage rise curve with only pure resistance and activation polarization.
[0124]
The method for obtaining the pure resistance using the voltage drop curve obtained as described above and the modified approximate expression of the voltage rise curve should be performed in the same manner as the modified approximate expression obtained using the current-time product. Therefore, detailed description is omitted.
[0125]
【The invention's effect】
  As explained above, claim 1And 14According to the invention, when the discharge current of the battery flowing along with the power supply to the load increases beyond the first predetermined value, the battery discharge current and the terminal voltage corresponding to the discharge current are obtained. The first approximate expression and the peak value of the current-voltage characteristic with respect to the discharge current which is periodically measured and shows the correlation between the measured discharge current and the terminal voltage and monotonously increases from the first predetermined value to the peak value. Since the second approximate expression of the current-voltage characteristic with respect to the discharge current that monotonously decreases from the current to a predetermined second predetermined value is obtained, the inrush current flowing through the load at the start of power supply to the load flows. Since the current-voltage characteristic indicating the relationship between the discharge current of the battery and the terminal voltage corresponding to the discharge current is measured, the two approximate expressions obtained do not include elements of the discharge current other than the inrush current, More accurate inrush current Battery current when the - to measure the voltage characteristicThe values of two terminal voltage changes per unit current change at points corresponding to the peak values of the first and second approximate expressions obtained by removing the voltage drop due to the concentration polarization component in the obtained first and second approximate expressions. Since the measured intermediate value is measured as the value of the battery's pure resistance, the battery's pure resistance is accurately measured when the battery is used in a normal state, that is, even when the vehicle is in use. It is possible to provide a battery pure resistance measuring method and apparatus capable of measuring Battery current-voltage characteristics measurement methodCan be provided.
[0127]
  Claim mentioned aboveItem 2According to the invention described above, the approximate expression can be calculated in real time while measuring the discharge current and the terminal voltage, and when the peak value does not exceed the predetermined third predetermined value, it is effective for measuring the pure resistance. Since the calculation of the approximate expression can be stopped on the assumption that the measured data is not correct, it is not necessary to store data in advance, and a large capacity for storing data is not required.
[0128]
  Claim mentioned aboveItem 3According to the invention described above, the unit current at the point where the intermediate value to be measured as the value of the pure resistance of the battery corresponds to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Since the value of two terminal voltage changes per change is obtained by averaging, the battery's net resistance that can accurately measure the battery's net resistance when the activation polarization changes at the point corresponding to the peak value are equal A measurement method can be provided.
[0129]
  Claim mentioned aboveItem 4According to the invention described above, the unit current at the point where the intermediate value to be measured as the value of the pure resistance of the battery corresponds to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. The time of the assumed monotonically increasing period and the assumed monotonically decreasing period in the total time that the assumed discharge current flows when assuming that the monotonously decreasing discharge current has been reduced to 0 to the value of the two terminal voltage changes per change Provided is a battery pure resistance measurement method capable of accurately measuring the battery pure resistance when the change in activation polarization at the point corresponding to the peak value is not equal because the ratio is obtained by multiplying the respective ratios and adding. be able to.
[0130]
  Claim mentioned aboveItem 5According to the invention described above, the pure resistance can be measured if the intermediate value is obtained by using the slope when the modified approximate expression is a linear expression and the differential value at the peak value when it is a quadratic expression. It is possible to provide a method for measuring a pure resistance of a battery, which can be measured by a simple calculation.
[0131]
  According to the invention described in claim 6 described above,The assumed discharge current flows to the value of the two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Considering that activation polarization and concentration polarization interact with each other by multiplying the ratios of the times of the expected monotonic increase period and the assumed monotonic decrease period in the total time. When the intermediate value can be obtained and measured as the value of the pure resistance of the battery, and the first and second approximate expressions are quadratic expressions, the first and second values are obtained in obtaining the intermediate value. Two terminals per unit current change at points corresponding to the peak values of the first and second modified approximate expressions are obtained by obtaining first and second modified approximate expressions excluding the voltage drop due to the concentration polarization component from the approximate expression. Finding the value of voltage change By, by obtaining an intermediate value by using a differential value at the peak value when the corrected approximation formula is quadratic, it is possible to measure the pure resistance, moreover,The difference between the terminal voltages of the battery at the point where the discharge current is zero in the first and second approximate expressions is due to the total concentration polarization component generated during the period when the assumed discharge current increases from 0 to the peak value and decreases from the peak value to 0. It is regarded as a voltage drop, a voltage drop due to the concentration polarization component that occurs until the assumed discharge current in the total concentration polarization component reaches a peak value from 0 is obtained, and the voltage value excluding this voltage drop is obtained as a first quadratic approximation. Since the quadratic expression obtained by substituting the equation, the constant, and the first-order coefficient into the equal expression is obtained as the first corrected approximate expression, the corrected approximate expression excluding the concentration polarization component can be obtained with high accuracy. Therefore, it is possible to provide a method for measuring a pure resistance of a battery, which can accurately measure a pure resistance.
[0132]
  Claim mentioned aboveItem 7According to the described invention, since the second secondary correction approximate expression excluding the voltage drop due to the concentration polarization component can be easily obtained, the pure resistance of the battery capable of measuring the pure resistance without troublesome processing. A measurement method can be provided.
[0133]
  Claim mentioned aboveItem 8According to the invention described above, when both the first and second modified approximate expressions are quadratic expressions, the battery can measure the pure resistance by a simple calculation for obtaining an intermediate value of the differential value at the peak value. It is possible to provide a pure resistance measuring method.
[0134]
  Claim mentioned aboveItem 9According to the described invention, since the second modified approximate expression of the quadratic expression is obtained by using the zero point that originally does not include the concentration polarization component, there are few processes for obtaining the approximate expression excluding the concentration polarization component. It is possible to provide a method for measuring a pure resistance of a good battery.
[0135]
  Claim mentioned aboveItem 10According to the described invention, since the slope of the second modified approximate expression is used to obtain the intermediate value, a battery pure resistance measurement method that simplifies the process for obtaining the intermediate value is provided. be able to.
[0136]
  Claim mentioned aboveItem 11According to the disclosed invention, the voltage drop due to the concentration polarization component that occurs until the assumed discharge current reaches the peak value from 0 is known, and the voltage value corresponding to the peak value excluding the voltage drop due to the concentration polarization component is obtained. Thus, it is possible to provide a battery pure resistance measuring method capable of obtaining the first modified approximate expression excluding the concentration polarization component with high accuracy and measuring the pure resistance with high accuracy.
[0137]
  Claim mentioned aboveItem 12According to the invention described above, similarly to the invention of claim 11, the voltage drop due to the concentration polarization component occurring until the assumed discharge current occupying the total concentration polarization component reaches a peak value from 0, and the voltage drop due to the concentration polarization component is known. Since the voltage value corresponding to the peak value excluding is obtained, the first modified approximate expression excluding the concentration polarization component can be obtained with high accuracy, and only the first and second approximate expressions are known. Since there is no need to obtain the current-time product, it is not affected by the corresponding relationship between the current-time product and the occurrence of concentration polarization, and no complicated processing is required. It is possible to provide a method for measuring a pure resistance of a battery capable of measuring a resistance.
[0138]
  Claim mentioned aboveItem 13According to the invention described above, when a discharge current that monotonously increases to the peak value flows in a short time without occurrence of concentration polarization, not only the process for measuring the pure resistance is simplified, but also an approximate expression It is also possible to provide a battery pure resistance measuring method that can be easily obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of a battery pure resistance measuring apparatus according to the present invention.
FIG. 2 shows a schematic configuration of a battery pure resistance measuring apparatus according to an embodiment of the present invention to which a battery pure resistance measuring method for measuring a pure resistance using a battery current-voltage characteristic measuring method of the present invention is applied. It is explanatory drawing shown in a partial block.
FIG. 3 is a graph showing an example of a discharge current accompanied with an inrush current at the start of driving a starter motor.
FIG. 4 is a graph showing an example of an IV characteristic represented by a quadratic approximate expression.
FIG. 5 is a graph for explaining an example of how to remove a concentration polarization component from an approximate expression in an increasing direction.
FIG. 6 is a graph for explaining an example of how to remove a concentration polarization component from an approximate expression in a decreasing direction.
FIG. 7 is a graph showing an example of an IV characteristic in which an increasing direction is expressed by a first-order approximation formula.
FIG. 8 shows an inrush current when an approximate expression is obtained using measurement data from the first predetermined value to the peak value and measurement data from the peak value to the second predetermined value. It is a graph for demonstrating how to obtain | require the total time and the time of a monotone increase period and a monotone decrease period.
FIG. 9 is a graph for explaining another example of how to remove the concentration polarization component from the approximate expression in the decreasing direction.
FIG. 10 is a graph for explaining another example of how to remove the concentration polarization component from the approximate expression in the decreasing direction.
11 is a flowchart showing processing performed by the microcomputer in FIG. 2 according to a predetermined program for pure resistance measurement.
FIG. 12 is a diagram for explaining how to obtain the peak current value point and the concentration polarization component at an arbitrary point based on the difference equation obtained by taking the difference between the equations (1) and (2). It is a graph of.
FIG. 13 is a graph showing IV characteristics generally showing a breakdown of a voltage drop of a terminal voltage due to discharge.
FIG. 14 is a graph for explaining a method of measuring a pure resistance of a conventional battery.
[Explanation of symbols]
23a-1 Current / voltage measuring means (CPU)
23a-2 Approximate expression calculation means (CPU)
23a-3 Calculation means (CPU)

Claims (14)

Monitoring the discharge current of the battery-when the inrush current to the load at the start power supply to the load flows the discharge current is increased beyond a first predetermined value determined in advance, the discharge current and the discharge current of the battery Periodically measure the corresponding terminal voltage,
The correlation between the measured discharge current and the terminal voltage is determined in advance from the first approximate expression of the current-voltage characteristic with respect to the discharge current monotonically increasing from the first predetermined value to the peak value and the peak value. current for the second monotonically decreasing discharge current to a predetermined value - and a second approximation formula of the voltage characteristics determined Me,
When the obtained first and second approximate expressions include a voltage drop due to a concentration polarization component, a unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop Find the middle value of the two terminal voltage changes per hit,
The obtained intermediate value is measured as the value of the pure resistance of the battery.
A method for measuring a pure resistance of a battery . In the pure resistance measurement method according to claim 1 Symbol placement of the battery,
Each time the discharge current and the terminal voltage are measured during a period in which the discharge current exceeds the first predetermined value and monotonously increases to the peak value, the first approximate expression is calculated based on the discharge current and the terminal voltage. Perform the calculation to find
The discharge current monotonously decreases from the peak value to the second predetermined value after the first approximate expression has been obtained for the discharge current whose peak value has increased beyond a predetermined third predetermined value. A method for measuring a pure resistance of a battery, characterized in that a calculation for obtaining the second approximate expression is sequentially performed based on the discharge current and the terminal voltage each time the discharge current and the terminal voltage are measured. In the pure resistance measurement method according to claim 1 Symbol placement of the battery,
The intermediate value is averaged by adding two terminal voltage change values per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. A method for measuring a pure resistance of a battery, characterized by: In the pure resistance measurement method according to claim 1 Symbol placement of the battery,
The intermediate value is changed to the value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Time of the assumed monotonically increasing period and the assumed monotonically decreasing period in the total time during which the assumed discharge current flows when it is assumed that the increasing discharge current increases from 0 and the monotonically decreasing discharge current has decreased to 0 A method for measuring a pure resistance of a battery, which is obtained by multiplying each of the ratios and adding them. In the battery pure resistance measuring method according to any one of claims 1 to 4 ,
When the first and second approximate expressions are quadratic expressions, in obtaining the intermediate value, the first and second approximate expressions obtained by removing the voltage drop due to the concentration polarization component from the first and second approximate expressions. A method for measuring a pure resistance of a battery, comprising: obtaining a corrected approximate expression and determining two terminal voltage change values per unit current change at a point corresponding to the peak value of the first and second corrected approximate expressions . In the pure resistance measurement method according to claim 1 Symbol placement of the battery,
The intermediate value is changed to the value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Time of the assumed monotonically increasing period and the assumed monotonically decreasing period in the total time that the assumed discharge current flows when it is assumed that the increasing discharge current increases from 0 and the monotonically decreasing discharge current decreases to 0 Is calculated by multiplying the percentages of
When the first and second approximate expressions are quadratic expressions, in obtaining the intermediate value, the first and second approximate expressions obtained by removing the voltage drop due to the concentration polarization component from the first and second approximate expressions. Obtaining a modified approximate expression, obtaining values of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second modified approximate expressions;
A difference in terminal voltage of the battery at a point where the discharge current is zero in the first and second approximate expressions is obtained, and the difference is a period in which the assumed discharge current increases from 0 to a peak value and decreases from a peak value to 0 The voltage drop due to the concentration polarization component occurring until the assumed discharge current occupying the total concentration polarization component reaches a peak value from 0 is obtained, and the obtained voltage drop is A secondary expression in which a secondary coefficient is determined by substituting a value obtained by removing a voltage value corresponding to a peak value into an expression in which a constant and a primary coefficient are equal to the first secondary approximation is used as the first modified approximation. A method for measuring a pure resistance of a battery, characterized by: In the pure resistance measurement method according to claim 6 Symbol mounting of the battery,
In addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, two voltage values excluding the voltage drop due to the concentration polarization component between the peak value and 0 are obtained, and the three voltage values are used. A method for measuring a pure resistance of a battery, comprising: obtaining a quadratic expression having a coefficient determined as the second modified approximate expression. In the pure resistance measurement method according to claim 7 Symbol mounting of the battery,
In order to obtain the intermediate value, a differential value at a peak value of the first and second modified approximate expressions is used. In the pure resistance measurement method according to claim 6 Symbol mounting of the battery,
In addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, two voltage values excluding the voltage drop due to the concentration polarization component at the zero point and an intermediate point between the peak value and 0 are obtained, A method for measuring a pure resistance of a battery, comprising: obtaining a quadratic expression in which a coefficient is determined using two voltage values as the second modified approximate expression. In the pure resistance measurement method according to claim 6 Symbol mounting of the battery,
In addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, a voltage value excluding the voltage drop due to the concentration polarization component at an intermediate point between the peak value and 0 is obtained and determined by connecting the two points. And determining the linear expression as the second modified approximate expression,
A method for measuring a pure resistance of a battery, wherein the slope of the second modified approximate expression is used to obtain the intermediate value. In the pure resistance measuring method of the battery according to any one of claims 6 to 10 ,
The voltage drop due to the concentration polarization component that occurs until the assumed discharge current occupying the total concentration polarization component reaches a peak value from 0 is a terminal of the battery at a point where the discharge current is 0 in the first and second approximate expressions. It is obtained by multiplying the voltage difference by the ratio of the current time product from 0 to the peak value to the current time product when the assumed discharge current increases from 0 to the peak value and decreases from the peak value to 0. Battery pure resistance measurement method. In the pure resistance measuring method of the battery according to any one of claims 6 to 10 ,
The difference between the two equations is obtained from the first and second approximate equations, and the voltage drop due to the concentration polarization component generated until the assumed discharge current occupying the total concentration polarization component reaches a peak value from 0 is calculated. The difference between the terminal voltage of the battery at the point where the discharge current is 0 in the first and second approximate expressions is twice the voltage value and the peak current value at the point where the current value is 0 based on the difference formula. It is obtained by multiplying the difference between the voltage value at the point that is the peak current value and the voltage value at the point that is the current value twice the peak current value with respect to the difference from the voltage value at the point that is the current value. To measure the pure resistance of the battery. In the battery pure resistance measuring method according to any one of claims 1 to 4 ,
When the load is to flow a discharge current that monotonously increases to the peak value in a short time without the occurrence of concentration polarization, the first approximate expression is a linear expression,
A method for measuring a pure resistance of a battery, wherein the slope of the first approximate expression is used to obtain the intermediate value. In a battery pure resistance measuring device for measuring a pure resistance of a battery mounted on a vehicle in order to supply electric power to a vehicle load,
A current that monitors the discharge current of the battery and periodically measures the discharge current of the battery and the terminal voltage corresponding to the discharge current when the discharge current increases beyond a predetermined first predetermined value. Voltage measuring means,
A first approximate expression of current-voltage characteristics with respect to a discharge current that monotonically increases from the first predetermined value to a peak value, showing a correlation between the discharge current measured by the current / voltage measuring means and the terminal voltage; An approximate expression calculating means for obtaining a second approximate expression of current-voltage characteristics with respect to a discharge current monotonously decreasing from a peak value to a predetermined second predetermined value;
When the first and second approximate expressions include a voltage drop due to a concentration polarization component, 2 per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop. And an arithmetic means for obtaining an intermediate value between two terminal voltage changes,
An intermediate value obtained by the calculating means is measured as a value of the pure resistance of the battery.

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