JP4110639B2 - Battery remaining capacity calculation device - Google Patents
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/005—Testing of electric installations on transport means
- G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
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Description
【０００１】
【発明の属する技術分野】
本発明は、たとえば電気自動車に搭載する電池の残存容量または劣化度を演算する電池の残存容量演算装置に関する。
【０００２】
【従来の技術】
電気自動車に用いる二次電池は充放電を繰り返すことにより、劣化により放電可能な容量が徐々に低下していくので、電池劣化を加味した残存容量（本明細書では放電可能電力量（ワット）又は放電量（アンペアアワー）を言うものとする）を正確に知ることが要望されている。このため、放電電圧Ｖと残存容量との関係をマップに記憶しておき、検出した放電電圧Ｖをこのマップに代入して残存容量を求める手法が従来より採用されている。なお、この方式では、上記関係が電池のメモリ効果の影響により変動するので、メモリ効果発生時の放電電圧Ｖと残存容量との関係を学習するようにしている。
【０００３】
特開平７−５５９０３号公報は、電流積算によって求めた放電量Ａｈを、あらかじめ記憶する満充電容量（満充電状態から所定の放電終止条件までの放電で得られる放電量）から差し引いて、残存容量を求めることを提案している。
特開平８−２７８３５２号公報は、計測した放電電圧及び放電電流とから、所定基準電流値における放電電圧に対応する残存容量を算出するとともに、計測した放電電圧及び放電電流とからなるデータがいままで収集したデータに比較して特異的な場合には残存容量算出を中止することを提案している。
【０００４】
ところが、これら従来の残存容量演算方式では、放電特性の劣化が電池劣化により生じたのかメモリ効果により生じたのかを区別できないため、正確に残存容量を演算することが困難であり、誤差が大きいという問題があった。
そこで、本出願人の出願になる特開平１０−２４６７６０号は、放電電圧Ｖと放電量Ａｈとの関係を示す初期特性マップをメモリ効果及び電池劣化に基づいてそれぞれ別々に修正して現在の放電電圧Ｖと放電量Ａｈとの関係を示す放電特性を形成し、この放電特性により決定される放電領域の面積を積分して残存放電可能電力量を求め、この残存放電可能電力量を残存容量として推定する方式（残存放電可能電力量推定式残存容量演算方式）を提案した。
【０００５】
【発明が解決しようとする課題】
しかしながら、上述した残存放電可能電力量推定方式においても、充放電を繰り返すうちに放電特性の形状、特に放電電圧の変化が顕著となる放電終期における放電特性の形状が、初期放電特性の形状からずれた残存容量演算誤差が大きくなるという問題があった。
【０００６】
本発明は上記問題点に鑑み、残存容量を正確に演算可能な電池の残存容量演算装置を提供することをその目的としている。
【０００７】
【課題を解決するための手段】
上記課題の解決のためになされた各請求項記載の電池の残存容量演算装置によれば、電池の内部抵抗と放電量との過去の関係を示す内部抵抗特性、電池の開放電圧と放電量との過去の関係を示す開放電圧特性、内部抵抗の今回値及び開放電圧の今回値に基づいて残存容量を演算する。すなわち、本構成では、残存容量を内部抵抗と放電量との関係、及び、開放電圧と放電量との関係に基づいて推定する。
【０００８】
このようにすれば、次に詳細に説明する理由により、メモリ効果を有する電池の残存容量を従来より格段に正確に推定することができる。
各請求項記載の構成によれば更に、開放電圧の今回値を変数とする所定の関数で過去の開放電圧特性を変形して今回の前記開放電圧特性を形成し、内部抵抗の今回値を変数とする所定の関数で過去の内部抵抗特性を変形して今回の前記内部抵抗特性を形成し、これら両今回の特性に基づいて残存容量を演算する。このようにすれば、メモリ効果を有する電池の残存容量を従来より格段に正確に推定することができる。
【０００９】
すなわち、各請求項記載の残存容量演算方式の特徴は、内部抵抗特性（内部抵抗と放電量との関係）及び開放電圧特性（開放電圧と放電量との関係）を用いることにより、残存容量を演算する。このようにすれば、電池の容量減少に対する電池劣化の影響と、メモリ効果の影響を正確に分別することができるので、正確に残存容量を演算することができる。言い換えれば、本構成では、電池劣化に起因する容量低下を推定した内部抵抗特性に基づいて推定し、メモリ効果に起因する容量低下を推定した開放電圧特性に基づいて推定するので、両電池容量低下原因を明瞭に分別して正確に残存容量を推定することができる。
【００１０】
更に説明すれば、電池は、等価回路的に、内部抵抗がない所定の開放電圧をもつ理想電池と、その内部抵抗に等しい抵抗素子とを直列接続した等価回路で表すことができる。この等価回路において、メモリ効果は電池の開放電圧の低下をもたらし、電池劣化は電池の内部抵抗の増大をもたらす。このことは、本出願人により出願された特開平１０−２４６７６０号によって明らかである。
【００１１】
したがって、メモリ効果による電池特性変化を開放電圧の変化として抽出し、電池劣化によるそれを内部抵抗の変化として抽出し、これら二つの容量低下要因を区別することが容易であるので、正確に残存容量の演算を行うことができる。
なお、内部抵抗特性及び開放電圧特性に基づいて残存容量を演算するには、たとえば請求項１に記載するように、今回の内部抵抗特性及び今回の開放電圧特性に基づいて求めた放電電圧と放電量との関係を示す放電特性を求め、この放電特性を現在の放電量値から所定の放電終了放電量値まで積分して残存容量を演算することができる。
【００１２】
結局、今回すなわち現時点の内部抵抗特性及び開放電圧特性が各放電量の値ごとに正確に推定できれば、それらに基づいて放電電圧と放電量との関係を容易に求めることができ、その積分により残存容量を正確に推定することができる。ちなみに、開放電圧をＯＣＶ、内部抵抗をｒとすれば、放電電圧Ｖ＝ＯＣＶ＋Ａ・ｒである。
【００１３】
図２にこの状態を模式的に示す。Ｃ１は基準とする過去の放電特性、Ｃ２は更に劣化した電池の現在の放電特性である。所定放電量値ＡＨ０における両者の電圧差ΔＶは、メモリ効果による開放電圧の差ΔＶｏと、電池劣化により内部抵抗ｒがΔｒだけ増大したことに起因する電圧差ΔＶｒ＝Ａ・Δｒとの合計である。
ここで重要なことは、放電量変化に伴う開放電圧の変化（すなわち、両者の間の関数関係）が、放電量変化に伴う内部抵抗の変化（すなわち、両者の間の関数関係）とまったく異なることである。両者がまったく同じであれば、放電量変化に伴う開放電圧の変化と放電量変化に伴う内部抵抗の変化とを区別する必要は存在しない。
【００１４】
メモリ効果による開放電圧の変化（低下）は、同じメモリ効果が生じている放電量範囲では同じであり、したがって、過去の開放電圧特性が確定していれば、ある放電量値でこの過去の開放電圧特性上での開放電圧値と今回（実測）の開放電圧値が分かれば両者の差だけ、過去の開放電圧特性をスライド（レベルダウン）させることにより今回の開放電圧特性を正確に推定することができる。
【００１５】
すなわち、請求項２に記載するように、過去の開放電圧特性上で放電量の今回値に対応する仮想の開放電圧値と開放電圧の今回値との間の電圧差をメモリ効果の量が異なる放電量範囲ごとにそれぞれ記憶し、放電量範囲ごとにこの電圧差だけ過去の開放電圧特性をスライドして今回の開放電圧特性とすればよい。
なお、メモリ効果による開放電圧の低下は、充電開始点から充電終了点までの放電量範囲において、この充電によりほぼ解消されるとみなすことができる。したがって、満充電状態と完全放電状態との間にて、それぞれ充電開始点や充電終了点が異なる複数の部分放電を実施した後では、各放電量範囲で開放電圧がそれぞれ異なることがわかる。したがって、それぞれ充放電履歴が異なる放電量範囲ごとに等放電量値に対応する過去の基準とする開放電圧の値と今回の開放電圧の値との間の電圧差をそれぞれメモリし、このメモリ値により過去の基準とする開放電圧特性のスライド量を変更すればよいことがわかる。
【００１６】
その例を図３に模式的に示す。
この図では、Ｃ３は初期開放電圧特性であり、Ｃ４は、最初、放電量値Ａｈ１まで放電後、満充電がなされ、その後、放電量値Ａｈ２まで放電後、満充電がなされ、その後の放電における開放電圧を示す。ΔＶ１は放電量値Ａｈ１〜Ａｈ２の放電量範囲でのメモリ効果による開放電圧低下を示し、ΔＶ２は放電量値Ａｈ２以降の放電量範囲でのメモリ効果による開放電圧低下を示す。
【００１７】
これに対し、電池劣化による内部抵抗の変化（増加）は、放電が深くなるにつれて（放電量の増大につれて）増大する傾向をもつ。したがって、今回の内部抵抗特性を過去の内部抵抗特性から推定するには、このような傾向を良好に示す関数で上記過去の内部抵抗特性を処理して今回の内部抵抗特性とする必要がある。そこで、本明細書では、請求項５、６に記載するように、以下に説明する二つの方法で、過去の基準とする内部抵抗特性の変形を行っている。
【００１８】
まず、請求項３記載の方法では、過去の内部抵抗特性上で放電量の今回値に対応する仮想の内部抵抗値と、内部抵抗の今回値との間の抵抗比を求め、過去の内部抵抗特性の内部抵抗軸をこの抵抗比だけ伸長して今回の内部抵抗特性とする。
このようにすれば、放電が進行して過去の内部抵抗特性上の内部抵抗値が増大するに応じて今回の内部抵抗特性上の内部抵抗値も増大するので上記傾向に対応することができるため、今回の内部抵抗特性と今回の真の内部抵抗特性との間の誤差を良好に減らすことができることが明らかである。
【００１９】
次に、請求項４記載の方法では、過去の内部抵抗特性上で内部抵抗の今回値に対応する仮想の放電量値と、放電量の今回値との間の放電量比を求め、過去の内部抵抗特性の放電量軸をこの放電量比だけ圧縮して今回の内部抵抗特性とする。
このようにすれば、放電が進行して過去の内部抵抗特性上の内部抵抗値が増大するに応じて今回の内部抵抗特性上の内部抵抗値も増大するので上記傾向に対応することができるため、今回の内部抵抗特性と今回の真の内部抵抗特性との間の誤差を良好に減らすことができることが明らかである。
【００２０】
なお、電池は劣化が進行するほど深放電状態において放電量の増大に応じた内部抵抗が特異的に増大することがわかっている。放電終期において電池劣化進行にしたがって、放電量増大よる内部抵抗の増大の様子を図４に模式的に示す。Ｃ５は初期内部抵抗特性であり、Ｃ６は電池劣化が進んだ内部抵抗特性である。
したがって、この放電終期における電池劣化時の内部抵抗の特異的な増大に対応した内部抵抗算出用関数と、その他の放電量範囲における内部抵抗算出用関数（放電終期特異的内部抵抗増加表現関数という）とを切り替えて、今回の内部抵抗特性を過去の基準となる内部抵抗特性から演算することができる。
上述した請求項４記載の内部抵抗算出方式によれば、この放電終期における電池劣化時の内部抵抗の特異的な増大（他の放電量範囲よりも急激に内部抵抗が増大する現象）を良好に示すことができる。
【００２１】
特に、放電終期特異的内部抵抗増加表現関数は、内部抵抗特性が徐々に変化していくことに鑑み、過去の基準とする内部抵抗特性をできるだけ直前の内部抵抗特性、好ましくは前回放電時の内部抵抗特性とすることが好適である。
なお、上記請求項１〜４記載の発明において、残存容量演算に用いる今回の開放電圧特性及び今回の内部抵抗特性を演算するための過去の開放電圧特性及び過去の内部抵抗特性は、直前の充電前の前回の放電において演算した前回の開放電圧特性及び前回の内部抵抗特性とすることができ、これは内部抵抗が不可逆的に徐々に変化する内部抵抗特性演算に特に好適である。
【００２２】
また、上記過去の開放電圧特性及び過去の内部抵抗特性は、初期（電池供用初期）時の初期開放電圧特性及び初期内部抵抗特性とすることができ、これは開放電圧が充電により可逆的に回復する開放電圧特性演算に特に好適である。
更に、電池使用時に満充電または所定の放電量値から完全放電まで放電される場合があった場合、この時の開放電圧特性及び内部抵抗特性を記憶し、その後はこれを基準に今回の開放電圧特性及び内部抵抗特性を上記方法で演算することも、誤差を減らす好適な方法である。
【００２３】
【発明の実施の形態】
本発明の電池の残存容量演算装置の好適な実施形態を図面に沿って以下に説明する。
【００２４】
【実施例】
（装置構成）
図１は、本発明に係るハイブリッド車用の残存容量演算装置の一例を示すブロック図である。
１は電池、２はハイブリッド車の回転電機を含む動力伝達手段であって、エンジン及び車両駆動軸に連結されてそれらと電池との間で電力の形態でエネルギー授受を行う。３は、電池１に対して入出力する直流電力と、動力伝達手段２に対して入出力する交流電力との変換を行う双方向電力変換装置である。これら動力伝達手段２や双方向電力変換装置３の構成は周知であり、かつ、本発明の要旨でもないので更に詳しい説明は省略する。なお、この実施例の電池の残存容量演算手段は、ハイブリッド車ではなく、内燃機関を搭載せず電池のみで走行する形式の電気自動車にも適用できることはもちろんである。
【００２５】
電池１は、多数のＮｉーＭＨ電池を直列接続してなる組み電池からなり、電流センサ５はその充放電電流を検出し、温度センサ６はその温度を検出し、これら電流、温度は電池１の出力電圧とともに電池劣化度を算出して表示するマイコン構成のコントローラ４に入力される。
（残存容量算出ルーチン１）
以下、図５に示すフローチャートを参照して、この実施例の残存容量算出プロセスの一例を説明する。
【００２６】
まず、現在放電中かどうかを調べ（Ｓ１０）、放電中であればＳ１２へ進み、放電中でなければＳ２６へ進む。
Ｓ１２では、実測した放電電圧Ｖ、放電電流Ａの各今回値から実測内部抵抗（内部抵抗の今回値）Ｒｍ及び実測開放電圧（開放電圧の今回値）ＯＣＶｍを算出し、更に放電の最初から現在までの放電電流Ａを累算して放電量の今回値Ａｈｍを求める。
【００２７】
なお、実測内部抵抗Ｒｍは、最近検出した放電電圧Ｖと放電電流Ａとのペアで規定される点を多数、Ｖ−Ａ二次元平面にプロットしてその一次近似直線を決定し、その傾斜率（ΔＶ／ΔＡ）により求める。次に、検出した放電電流Ａと実測内部抵抗Ｒｍを掛けてその電圧降下を求め、この電圧降下を上記放電電圧Ｖの今回値に加算して実測開放電圧ＯＣＶｍを求める。
【００２８】
次に、今回放電における内部抵抗特性を示すＲａｍマップを作成する（Ｓ１６）。なお、この実施例では、このＲａｍマップは、直前の充電前の前回の放電時に作成した前回Ｒａｍマップを修正して作成するものとする。また、最初に作成するＲａｍマップはあらかじめ記憶する初期内部抵抗特性を示す初期Ｒａｍマップを修正して作成することはもちろんである。
【００２９】
まず、前回Ｒａｍマップに実測内部抵抗Ｒｍを代入して、この前回Ｒａｍマップ上で実測内部抵抗Ｒｍに対応する仮想的な放電量の値Ａｈｘを求める。
次に、放電量Ａｈの今回値Ａｈｍと仮想値Ａｈｘとの比を求め、この比で、前回Ｒａｍマップを示す二次元平面の放電量を示す軸（放電量軸という）を比例圧縮する操作（容量減少操作）を行って今回のＲａｍマップとする。
【００３０】
なお、今回のＲａｍマップをどのように作成するかには種々の方法が考えられるが、過去の所定放電回めのＲａｍマップの各内部抵抗値にそれぞれ所定の変換関数を示すマップの各変換係数値を掛けて求めることもできる。更に、この変換関数を示すマップを放電回数の累積ととともに書き換えることもできる。
次に、あらかじめ記憶する開放電圧マップＯＣＶａｍと上記Ｒａｍマップとから基準放電電力値での放電特性マップを作成する（Ｓ１８）。なお、ここでいう基準放電電力値での放電特性とは、所定の基準放電電力（ここでは２ｋＷ）を放電する場合の電池の出力電圧（放電電圧）Ｖと放電量Ａｈとの関係を示す特性である。
【００３１】
更に説明すると、任意の放電量Ａｈの値に対応する放電電圧Ｖは、この放電量Ａｈの値に対応して補正開放電圧特性から求めた開放電圧値ＯＣＶ’と、この放電量Ａｈの値に対応して補正内部抵抗特性から求めた内部抵抗値Ｒ’から次の二次関数式により算出される。ただし、Ｗは基準放電電力値、Ａはこの放電量Ａｈにおける放電電流値である。
【００３２】
Ｖ＝ＯＣＶ’−Ｒ’・Ａ＝ＯＣＶ’−Ｒ’・Ｗ／Ｖ
次に、Ｓ１８で求めた放電特性から残存容量の演算を行う（Ｓ２０）。
すなわち、上記放電特性を、放電量Ａｈの今回値Ａｈｍから電池がもはや所定の基準放電電力で放電できない放電量まで積分して、基準放電電力放電可能な残存容量を求める。
【００３３】
次に、放電が終了して充電開始したかどうかを調べ（Ｓ２２）、そうでない場合にはＳ２６へジャンプし、そうである場合にはこの充電開始直前の放電量値Ａｈｘを記憶する（Ｓ２４）。これは、メモリ効果による開放電圧低下が、次回の放電においてこの放電量値Ａｈｘから始まるからである。
次に、放電が直前の充電動作開始時点の放電量値Ａｈｘにまで達したかどうかを調べる（Ｓ２６）。達していなければＳ２８における開放電圧マップＯＣＶａｍの書き換えは行わずにメインルーチンにリターンし、達していれば、記憶する開放電圧マップＯＣＶａｍ上でのこの時点の放電量Ａｈの今回値Ａｈｘに対応する前回の開放電圧値ＯＣＶｘと、放電量Ａｈの今回値Ａｈｘに対応する今回の実測開放電圧ＯＣＶｍとの差ΔＶを求め、記憶する開放電圧マップＯＣＶａｍのこの放電量Ａｈの今回値Ａｈｍより大きい放電量範囲において、開放電圧をΔＶだけ下方にスライドさせる（Ｓ２８）。これにより直前のメモリ効果による開放電圧低下を開放電圧マップＯＣＶａｍに書き込むことができる。もちろん、最初の充電の後での開放電圧マップＯＣＶａｍの修正は、あらかじめ記憶する初期開放電圧特性を示す初期Ｒａｍマップを用いて行う。
【００３４】
次に、Ｓ１０にて、放電中でなければ、充電が終了したかどうかを調べ（Ｓ３０）、そうでないならメインルーチンにリターンし、充電が終了したら、記憶する開放電圧マップＯＣＶａｍ中のこの充電動作がなされた充電量範囲の開放電圧の値をあらかじめ記憶する初期開放電圧特性（すなわち初期開放電圧ＯＣＶマップ）の値に回復させる。これにより、メモリ効果による開放電圧低下分の充電動作による回復作用を開放電圧マップＯＣＶａｍに反映させることができる。
（残存容量算出ルーチン２）
以下、図６〜図７に示すフローチャートを参照して、この実施例の残存容量算出プロセスを説明する。
【００３５】
・実測パラメータ算出（ステップＳ１００）、
まず、実測した放電電圧Ｖ、放電電流Ａの各今回値から実測内部抵抗Ｒｍ及び実測開放電圧ＯＣＶｍを算出し、更に放電の最初から現在までの放電電流Ａを累算して放電量の今回値Ａｈｍを求める。
なお、実測内部抵抗Ｒｍは、最近検出した放電電圧Ｖと放電電流Ａとのペアで規定される点を多数、Ｖ−Ａ二次元平面にプロットしてその一次近似直線を決定し、その傾斜率（ΔＶ／ΔＡ）により求める。次に、検出した放電電流Ａと実測内部抵抗Ｒｍを掛けてその電圧降下を求め、この電圧降下を上記放電電圧Ｖの今回値に加算して実測開放電圧ＯＣＶｍを求める。
【００３６】
・関連する初期パラメータ算出（ステップＳ１０２）
次に、電池の運用初期時における初期内部抵抗Ｒｉｎｉと放電量との関係を示す初期内部抵抗特性（あらかじめ初期内部抵抗マップとして記憶）に上記した放電量の今回値Ａｈｍの値を代入して、放電量の今回値Ａｈｍに対応する初期内部抵抗特性上の初期内部抵抗Ｒｉｎｉの今回値を求め、更に、この初期内部抵抗Ｒｉｎｉの今回値と、検出した放電電圧Ｖの今回値及び放電電流Ａの今回値とから上記初期内部抵抗Ｒｉｎｉの今回値に対応する初期開放電圧ＯＣＶｉｎｉの今回値（＝Ｒｉｎｉ・Ａ＋Ｖ）を算出する。
【００３７】
・放電終期判断（ステップＳ１０６）
次に、放電終期における内部抵抗の補正のために、現在、放電終期（又は放電後半期）かどうかの判断材料として現時点における初期特性上の残存容量の今回値Ｑｒｉｎｉを算出する。この初期特性上の残存容量の今回値Ｑｒｉｎｉは、あらかじめ記憶する初期時満充電容量Ｑｒｆｕｌｌ（Ａｈ）から上記した放電量の今回値Ａｈｍ（Ａｈ）を差し引いた値である。
【００３８】
次に、初期特性上の残存容量の今回値Ｑｒｉｎｉが初期時満充電容量Ｑｉｎｉｆｕｌｌに所定の定数ｘを掛けて求めた所定のしきい値未満かどうかを調べる。そして、未満であれば、放電終期又は放電後半期であって電池の内部抵抗の特異的な増大が生じる可能性があると判断して次のＳ１１０へ進み、以上であれば上記放電終期における特異的な内部抵抗の増大現象が生じる可能性はなく、Ｓ１１４で行うその補正は不必要としてＳ１２２へジャンプする。つまり、この判断ステップは、上記放電終期における特異的な内部抵抗Ｒの増大現象が生じるはずがない浅い放電量領域において、Ｓ１１４で行う内部抵抗補正操作を誤って実施することがないようにするためのものである。たとえば、定数ｘは１未満の定数であり、たとえば０．５に設定される。
【００３９】
なお、Ｓ１０６では、初期特性上の残存容量の今回値Ｑｒｉｎｉと初期時満充電容量Ｑｉｎｉｆｕｌｌとの比較により、放電終期または放電後半期かどうかを判定したが、前回求めた満充電容量Ａｈと現在の放電量Ａｈとの同様の比較によりそれを求めてもよく、初期時における所定放電電力での放電による満充電容量と、今までの上記所定放電電力での放電による放電容量との同様の比較によりそれを求めてもよい。
【００４０】
・放電終期における内部抵抗増大判定（ステップＳ１１０）
次に、前回求めた補正内部抵抗特性（補正内部抵抗Ｒａｍｅｎｄと放電量Ａｈとの関係を示す特性、前回Ｒａｍマップともいう）に上記した放電量Ａｈの今回値Ａｈｍの値を代入して、この放電量Ａｈの今回値Ａｈｍに対応する前回Ｒａｍマップ上における補正内部抵抗Ｒａｍｅｎｄの値（前回値という）Ｒａｍｂｅｆｏｒｅを求める。
【００４１】
次に、実測内部抵抗Ｒｍが、このＲａｍｂｅｆｏｒｅに所定の定数ｙを掛けて求めた所定のしきい値を超えるかどうかを調べ、超えれば上記放電終期における特異的な内部抵抗の増大現象が生じているものと判断してＳ１１２へ進み、以下であれば上記増大現象は生じておらず、それを補償するＳ１１４における補正は不要であると判断してＳ１１６へ進む。たとえば定数ｙは１を超える定数である。
【００４２】
なお、Ｓ１１０では、上記した放電量Ａｈの今回値Ａｈｍに対応する前回Ｒａｍマップ上の内部抵抗値Ｒａｍｂｅｆｏｒｅと実測内部抵抗Ｒｍとの比較により放電終期における内部抵抗急増現象の発生の有無を判定したが、放電量Ａｈの今回値Ａｈｍに対応する初期内部抵抗特性上の補正内部抵抗Ｒｉｎｉの前回値Ｒｉｎｉｂｅｆｏｒｅと実測内部抵抗Ｒｍとの比較により放電終期における内部抵抗急増現象の発生の有無を判定してもよい。
【００４３】
・放電終期の内部抵抗急増現象の補正１（ステップＳ１１２）
次に、直前の充電前の前回放電時に求めた補正内部抵抗特性（前回Ｒａｍマップ）に実測内部抵抗Ｒｍを代入して、この前回Ｒａｍマップ上で実測内部抵抗Ｒｍに対応する放電量の値Ａｈｘを求める。
なお、Ｓ１１２では、直前の充電前の前回放電時に求めた補正内部抵抗特性（前回Ｒａｍマップ）に実測内部抵抗Ｒｍを代入して、この前回Ｒａｍマップ上で実測内部抵抗Ｒｍに対応する放電量の値Ａｈｘを求めたが、初期内部抵抗特性（初期Ｒａｍマップ）に実測内部抵抗Ｒｍを代入して、この初期Ｒａｍマップ上で実測内部抵抗Ｒｍに対応する放電量の値Ａｈｘを求めてもよい。
【００４４】
・放電終期の内部抵抗急増現象の補正２（ステップＳ１１４）
次に、放電量Ａｈの今回値Ａｈｍと上記前回Ｒａｍマップ上の放電量の値Ａｈｘとの比を求め、この比で、前回Ｒａｍマップを示す二次元平面の放電量を示す軸線（放電量軸という）を比例圧縮する操作（容量減少操作）を行って今回の補正内部抵抗特性（今回Ｒａｍマップ）を求める。
【００４５】
なお、Ｓ１１４では、放電量Ａｈの今回値Ａｈｍと上記前回Ｒａｍマップ上の放電量の値Ａｈｘとの比で前回Ｒａｍマップの放電量軸を比例圧縮したが、その代わりに、放電量Ａｈの今回値Ａｈｍと初期Ｒａｍマップ上の放電量の値Ａｈｘｉｎｉとの比で初期Ｒａｍマップの放電量軸を比例圧縮してもよい。
なお、この放電終期の内部抵抗急増現象は、放電終期に出現する現象であるので、上記放電量軸の圧縮操作による前回内部抵抗特性（前回Ｒａｍマップ）の修正は、Ｓ１１０で内部抵抗急増を検出した時点の放電量値より大きい放電量の範囲でのみ実施され、この時点以前の放電量範囲ではこの放電量軸の圧縮操作は実施しない。
【００４６】
これにより、放電終期における内部抵抗急増現象を補正内部抵抗Ｒａｍｅｎｄと放電量Ａｈとの関係を示す前回補正内部抵抗特性（前回Ｒａｍマップ）に反映させて、今回補正内部抵抗特性（今回Ｒａｍマップ）を求めることができる。
・電池劣化による内部抵抗増大に対する補正１（ステップＳ１１６）
次に、Ｓ１０６、Ｓ１１０の判定で、放電が浅い放電量範囲であると判定した場合、若しくは、内部抵抗急増が生じていないと判定した場合には、前回Ｒａｍマップ上において放電量Ａｈの今回値Ａｈｍに対応する補正内部抵抗Ｒａｍｅｎｄの値（前回値という）Ｒａｍｂｅｆｏｒｅと、実測内部抵抗Ｒｍとを比較し、実測内部抵抗Ｒｍが、この前回Ｒａｍマップ上の等価的な内部抵抗の値Ｒａｍｂｅｆｏｒｅｘに所定の定数ｚを掛けたしきい値より大きいかどうかを調べ、大きい場合には、電池劣化による内部抵抗増加が前回の補正内部抵抗特性（前回Ｒａｍマップ）の修正を必要となほど進行したと判定して次のＳ１２０へ進み、以下であれば電池劣化による内部抵抗増加が前回の補正内部抵抗特性（前回Ｒａｍマップ）の修正を必要とするほど進行していないと判定してＳ１２２へジャンプする。
・電池劣化による内部抵抗増大に対する補正２（ステップＳ１２０）
次に、前回Ｒａｍマップが表示される二次元平面の内部抵抗を示す軸（内部抵抗軸）を、実測内部抵抗Ｒｍと、放電量Ａｈの今回値Ａｈｍに対応する前回Ｒａｍマップ上の内部抵抗の値Ｒａｍｂｅｆｏｒｅとの比率で伸長（抵抗値増大）して今回の補正内部抵抗特性（今回Ｒａｍマップ）とする。すなわち、ある放電量の値Ａｈ０に対する今回Ｒａｍマップ上の補正内部抵抗値Ｒａｍ０は、この放電量の値Ａｈ０にそれぞれ対する実測内部抵抗値Ｒｍ０と前回内部抵抗値Ｒａｍｂｅｆｏｒｅ０との比（Ｒｍ０／Ｒａｍｂｅｆｏｒｅ０）と、この放電量値Ａｈ０に対する前回Ｒａｍマップ上の補正内部抵抗値Ｒａｍ０とを掛けたものとなる。
【００４７】
これにより、電池の劣化に起因する内部抵抗の増大を加味した今回の補正内部抵抗特性（Ｒａｍマップ）を得ることができる。
この結果、通常の電池劣化による内部抵抗の増加はＳ１２０の内部抵抗軸の伸長で求め、放電終期における特異的な内部抵抗の増大はＳ１１４における放電量軸の圧縮で求めることができる。
【００４８】
・メモリ効果による開放電圧低下の補正１（ステップＳ１２２、Ｓ１２４）
次のＳ１２２では、放電が直前の充電動作開始時点の放電量値Ａｈｘにまで達したかどうかを調べ、達していなければＳ１２６へ進み、達していれば、現在の放電量Ａｈの今回値Ａｈｘにおける開放電圧ＯＣＶの値（放電終了時点の開放電圧ＯＣＶｍ）と初期開放電圧特性上の現在の放電量Ａｈの今回値Ａｈｘに対応する値との電圧差ΔＶを、現在の放電量Ａｈの今回値Ａｈｘとペアで記憶し（Ｓ１２４）、Ｓ１２６へ進む。これは、次回の放電時に、この放電量Ａｈｘ以降の放電に対してメモリ効果による開放電圧ＯＣＶがΔＶだけ低下することを記憶するためである。
【００４９】
・メモリ効果による開放電圧低下の補正２（ステップＳ１２６）
このステップでは、開放電圧特性の補正を行う。
この開放電圧の補正は次のように行う。
まず、直前の充電動作で充電がなされた放電量範囲においては、メモリ効果による開放電圧ＯＣＶの低下が解消されたと考えて、初期開放電圧特性を今回の開放電圧特性とするとともに、この放電量範囲において、いままでのＳ１２４で記憶した１乃至複数の上記ペアを消す。
【００５０】
次に、直前の充電動作で充電がなされなかった放電量範囲においては、メモリ効果による開放電圧ＯＣＶの低下が残留していると考えて、この放電量範囲においていままでのＳ１２４で記憶した放電終了時点の放電量値と電圧差ΔＶとの１乃至複数のペアに基づいて、初期開放電圧特性（ＯＣＶｉｎｉマップ）上の開放電圧ＯＣＶを示す軸線（開放電圧軸）を電圧減少方向に上記電圧差ΔＶだけスライドさせて、補正開放電圧特性とする操作を行う。これにより、メモリ効果による起電圧の劣化を補正開放電圧特性に表すことができる。
【００５１】
なお、上記スライド操作は複数回実施されることが有り得る。たとえば、最初に満充電から放電量値１００Ａｈまで放電し、その後、満充電してから放電量値７０Ａｈまで放電し、次に満充電してから放電量値５０Ａｈまで放電した時点を考える。この時点では、放電量０Ａｈから７０Ａｈまではほぼ開放電圧ＯＣＶは初期開放電圧に回復しているが、放電量値７０Ａｈで電圧差ΔＶ１だけ初期開放電圧からの開放電圧ＯＣＶの低下が生じており、放電量値１００Ａｈで電圧差ΔＶ２だけ初期開放電圧からの開放電圧ＯＣＶの低下が生じている。
【００５２】
したがって、この放電量値７０Ａｈで電圧差ΔＶ１だけ初期開放電圧をレベルシフトさせ、更に放電量値１００Ａｈで電圧差ΔＶ２だけ初期開放電圧をレベルシフトさせることにより今回の開放電圧特性を決定することができる。
・基準放電電力値での放電特性の演算（Ｓ１２８）
次に、Ｓ１１４又はＳ１２０で求めた今回の補正内部抵抗特性及びＳ１２６で求めた今回の補正開放電圧特性を用いて基準放電電力値での放電特性の演算を行う。なお、ここでいう基準放電電力値での放電特性とは、所定の基準放電電力（ここでは２ｋＷ）を放電する場合の電池の出力電圧（放電電圧）Ｖと放電量Ａｈとの関係を示す特性である。
【００５３】
更に説明すると、任意の放電量Ａｈの値に対応する放電電圧Ｖは、この放電量Ａｈの値に対応して補正開放電圧特性から求めた開放電圧値ＯＣＶ’と、この放電量Ａｈの値に対応して補正内部抵抗特性から求めた内部抵抗値Ｒ’から次の二次関数式により算出される。ただし、Ｗは基準放電電力値、Ａはこの放電量Ａｈにおける放電電流値である。
【００５４】
Ｖ＝ＯＣＶ’−Ｒ’・Ａ＝ＯＣＶ’−Ｒ’・Ｗ／Ｖ
・残存容量の演算（Ｓ１３０）
このステップでは、Ｓ１２８で求めた所定の基準放電電力（ここでは２ｋＷ）での放電特性を、放電量Ａｈの今回値Ａｈｍから電池がもはや所定の基準放電電力で放電できない放電量まで積分して、基準放電電力放電可能な残存容量を求め、メインルーチンにリターンする。
（実施例の効果）
上記説明したこの実施例では、内部抵抗特性と開放電圧特性とに基づいて求めた放電特性から残存容量を求めるので、従来より正確に残存容量を算出することができる。
【００５５】
すなわち、メモリ効果を有する電池では、メモリ効果による残存容量の減少は内部抵抗の増大ではなく開放電圧の低下で表現でき、電池劣化による残存容量の減少は開放電圧の低下ではなく内部抵抗の増大で表現できることが、前述した本出願人出願の従来技術で示されている。
ここで重要なことは、内部抵抗が放電量又は残存容量に応じて、更に正確に言えば、満充電量に対する放電量又は残存容量に応じてある関数で変化する値であり、この関数変化を補償するには、この関数によって放電電圧−放電容量を示す放電特性の放電量軸の圧縮を行うことが要求される。一方、メモリ効果による開放電圧の低下は各放電量の値に対して一定であり、この一定の開放電圧低下を補償するには、この放電電圧に占める開放電圧低下量だけ、放電電圧−放電容量を示す放電特性の放電量軸のレベルダウンを行う必要がある。
【００５６】
しかし、前述した本出願人出願の従来技術では、ある放電量で生じた直前の充電前の放電における放電電圧と、同一の放電量で生じた今回計測した放電電圧との電圧差のうち、メモリ効果に起因する成分（レベルシフトすべき電圧成分）と、電池劣化に起因する成分（放電量軸圧縮で補償するべき電圧成分）との割合が不明であり、正確に上記レベルシフト補償と、容量軸圧縮補償とを実施できず、それが残存容量演算誤差となることである。
【００５７】
これに対し、この実施例では、内部抵抗特性と開放電圧ＯＣＶ特性とを用いることにより、電池劣化による内部抵抗増大を、放電量軸の圧縮又は内部抵抗軸の伸長で正確に対応し、かつ、メモリ効果による開放電圧低下を、開放電圧軸のスライドで正確に対応するので、現時点以降の残存容量を、初期開放電圧特性と初期内部抵抗特性のペア、又は、前回開放電圧特性と前回内部抵抗特性のペアと、実測した開放電圧値及び内部抵抗値に基づいて、正確に求めることができる。
【００５８】
更に、電池の劣化が進行すると、電池の放電終期において内部抵抗が急激に増大する現象に対してはそれを判別して対処しているので、一層正確に残存容量を演算することができる。
【図面の簡単な説明】
【図１】本発明の電池の残存容量演算装置の一実施例を示すブロック図である。
【図２】放電量Ａｈと放電電圧Ｖとの関係を示す模式特性図である。
【図３】放電量Ａｈと内部抵抗ｒとの関係を示す模式特性図である。
【図４】放電量Ａｈと開放電圧マップＯＣＶとの関係を示す模式特性図である。
【図５】残存容量演算処理１を示すフローチャートである。
【図６】残存容量演算処理２を示すフローチャートである。
【図７】残存容量演算処理２を示すフローチャートである。
【符号の説明】
１は電池、４はコントローラ、５は電流センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery remaining capacity computing device that computes the remaining capacity or the degree of deterioration of a battery mounted on, for example, an electric vehicle.
[0002]
[Prior art]
The secondary battery used in the electric vehicle is repeatedly charged and discharged, so that the capacity that can be discharged gradually decreases due to deterioration. Therefore, the remaining capacity that takes into account battery deterioration (in this specification, dischargeable electric energy (watts) or It is desired to know the amount of discharge (ampere hour) accurately. For this reason, a method of storing the relationship between the discharge voltage V and the remaining capacity in a map and substituting the detected discharge voltage V into the map to obtain the remaining capacity has been conventionally employed. In this method, since the above relationship varies due to the influence of the memory effect of the battery, the relationship between the discharge voltage V and the remaining capacity when the memory effect occurs is learned.
[0003]
Japanese Patent Laid-Open No. 7-55903 discloses a method of subtracting the discharge amount Ah obtained by current integration from a pre-stored full charge capacity (a discharge amount obtained by discharge from a full charge state to a predetermined discharge termination condition) to obtain a remaining capacity. Propose to seek.
In Japanese Patent Laid-Open No. 8-278352, while calculating the remaining capacity corresponding to the discharge voltage at a predetermined reference current value from the measured discharge voltage and discharge current, data consisting of the measured discharge voltage and discharge current has so far been obtained. It proposes to cancel the remaining capacity calculation when it is specific compared to the collected data.
[0004]
However, in these conventional remaining capacity calculation methods, it is difficult to accurately calculate the remaining capacity because the discharge characteristics are deteriorated due to the battery deterioration or the memory effect, and the error is large. There was a problem.
Therefore, Japanese Patent Application Laid-Open No. 10-246760 filed by the applicant of the present application corrected the initial characteristic map indicating the relationship between the discharge voltage V and the discharge amount Ah separately based on the memory effect and the battery deterioration, respectively. A discharge characteristic indicating the relationship between the voltage V and the discharge amount Ah is formed, and the remaining dischargeable electric energy is obtained by integrating the area of the discharge region determined by the discharge characteristic, and the remaining dischargeable electric energy is defined as the remaining capacity. An estimation method (estimated residual electric energy estimation formula remaining capacity calculation method) was proposed.
[0005]
[Problems to be solved by the invention]
However, even in the above-described method for estimating the remaining dischargeable electric energy, the shape of the discharge characteristics, particularly the shape of the discharge characteristics at the end of discharge where the change in the discharge voltage becomes noticeable as charging and discharging are repeated, deviates from the shape of the initial discharge characteristics. There is a problem that the residual capacity calculation error becomes large.
[0006]
In view of the above problems, an object of the present invention is to provide a battery remaining capacity calculation device capable of accurately calculating a remaining capacity.
[0007]
[Means for Solving the Problems]
Made to solve the above issueseachAccording to the battery remaining capacity calculation device according to the claim, the internal resistance characteristic indicating the past relationship between the internal resistance of the battery and the discharge amount, the open circuit voltage characteristic indicating the past relationship between the open voltage of the battery and the discharge amount, The remaining capacity is calculated based on the current value of the internal resistance and the current value of the open circuit voltage. That is, in this configuration, the remaining capacity is estimated based on the relationship between the internal resistance and the discharge amount, and the relationship between the open circuit voltage and the discharge amount.
[0008]
In this way, the remaining capacity of the battery having the memory effect can be estimated much more accurately than before for the reason described in detail below.
According to the structure described in each claim,The past open-circuit voltage characteristics are transformed by a predetermined function having the current value of the open-circuit voltage as a variable to form the current open-circuit voltage characteristic, and the past internal resistance is determined by a predetermined function having the current value of the internal resistance as a variable. The characteristic is modified to form the current internal resistance characteristic, and the remaining capacity is calculated based on both the current characteristics. In this way, the remaining capacity of the battery having a memory effect can be estimated much more accurately than before.
[0009]
That is,In each claimThe remaining capacity calculation method is characterized in that the remaining capacity is calculated by using internal resistance characteristics (relationship between internal resistance and discharge amount) and open-circuit voltage characteristics (relationship between open-circuit voltage and discharge amount). In this way, the influence of the battery deterioration on the battery capacity reduction and the influence of the memory effect can be accurately distinguished, so that the remaining capacity can be calculated accurately. In other words, in this configuration, since the estimation is based on the internal resistance characteristic that estimates the capacity decrease due to the battery deterioration and the estimation based on the open-circuit voltage characteristic that estimates the capacity decrease due to the memory effect, both battery capacity decreases The remaining capacity can be accurately estimated by clearly separating the cause.
[0010]
More specifically, the battery can be represented by an equivalent circuit in which an ideal battery having a predetermined open-circuit voltage having no internal resistance and a resistance element equal to the internal resistance are connected in series as an equivalent circuit. In this equivalent circuit, the memory effect causes a decrease in the open circuit voltage of the battery, and the battery deterioration causes an increase in the internal resistance of the battery. This is apparent from Japanese Patent Laid-Open No. 10-246760 filed by the present applicant.
[0011]
Therefore, it is easy to extract the battery characteristics change due to the memory effect as a change in open circuit voltage, extract it as a change in internal resistance due to battery deterioration, and distinguish these two capacity reduction factors, so the remaining capacity can be accurately Can be performed.
In order to calculate the remaining capacity based on the internal resistance characteristics and the open-circuit voltage characteristics, for example, claims1As shown in Fig. 4, discharge characteristics indicating the relationship between the discharge voltage and the discharge amount obtained based on the current internal resistance characteristic and the current open-circuit voltage characteristic are obtained, and the discharge characteristic is determined from the current discharge amount value to a predetermined discharge amount. The remaining capacity can be calculated by integrating up to the end discharge amount value.
[0012]
After all, if the current internal resistance characteristics and the open circuit voltage characteristics can be accurately estimated for each discharge amount value, the relationship between the discharge voltage and the discharge amount can be easily obtained based on these values, and the residual can be obtained by integration. The capacity can be estimated accurately. Incidentally, if the open circuit voltage is OCV and the internal resistance is r, the discharge voltage V = OCV + A · r.
[0013]
FIG. 2 schematically shows this state. C1 is a past discharge characteristic as a reference, and C2 is a current discharge characteristic of a further deteriorated battery. The voltage difference ΔV between the two at the predetermined discharge amount value AH0 is the sum of the difference ΔVo of the open circuit voltage due to the memory effect and the voltage difference ΔVr = A · Δr resulting from the increase of the internal resistance r by Δr due to battery deterioration. .
What is important here is that the change in open-circuit voltage accompanying the change in discharge amount (ie, the functional relationship between the two) is completely different from the change in internal resistance accompanying the change in discharge amount (ie, the functional relationship between the two). That is. If they are exactly the same, there is no need to distinguish between a change in open circuit voltage due to a change in discharge amount and a change in internal resistance due to a change in discharge amount.
[0014]
The change (decrease) in the open-circuit voltage due to the memory effect is the same in the discharge amount range where the same memory effect occurs. Therefore, if the past open-circuit voltage characteristics have been established, this past open-circuit value at a certain discharge amount value. If the open-circuit voltage value on the voltage characteristic and the open-circuit voltage value of this time (actual measurement) are known, the open-circuit voltage characteristic of this time is accurately estimated by sliding the previous open-circuit voltage characteristic (level down) by the difference between the two. Can do.
[0015]
That is, the claim2The voltage difference between the virtual open-circuit voltage value corresponding to the current value of the discharge amount in the past open-circuit voltage characteristics and the current value of the open-circuit voltage is calculated for each discharge amount range with different amounts of memory effect. Each of them is stored, and the past open-circuit voltage characteristics may be slid by this voltage difference for each discharge amount range to obtain the current open-circuit voltage characteristics.
Note that the decrease in the open-circuit voltage due to the memory effect can be considered to be substantially eliminated by this charging in the discharge amount range from the charging start point to the charging end point. Therefore, it can be seen that the open circuit voltage is different in each discharge amount range after a plurality of partial discharges having different charge start points and charge end points between the fully charged state and the fully discharged state. Therefore, the memory stores the voltage difference between the open-circuit voltage value as the past reference corresponding to the equal discharge amount value and the current open-circuit voltage value for each discharge amount range with different charge / discharge histories. Thus, it can be understood that the slide amount of the open circuit voltage characteristic as a past reference may be changed.
[0016]
An example is schematically shown in FIG.
In this figure, C3 is an initial open-circuit voltage characteristic, and C4 is first fully charged after discharging to a discharge amount value Ah1, and then fully charged after discharging to a discharge amount value Ah2. Indicates the open circuit voltage. ΔV1 indicates the open circuit voltage drop due to the memory effect in the discharge amount range of the discharge amount values Ah1 to Ah2, and ΔV2 indicates the open circuit voltage drop due to the memory effect in the discharge amount range after the discharge amount value Ah2.
[0017]
On the other hand, the change (increase) in internal resistance due to battery deterioration tends to increase as the discharge becomes deeper (as the discharge amount increases). Therefore, in order to estimate the current internal resistance characteristic from the past internal resistance characteristic, it is necessary to process the past internal resistance characteristic with a function that shows such a tendency well to obtain the current internal resistance characteristic. Therefore, in the present specification, as described in
[0018]
First, claims3In the described method, the resistance ratio between the virtual internal resistance value corresponding to the current value of the discharge amount on the past internal resistance characteristics and the current value of the internal resistance is obtained, and the internal resistance axis of the past internal resistance characteristics is obtained. Is increased by this resistance ratio to obtain the current internal resistance characteristics.
In this way, as the internal resistance value in the past internal resistance characteristic increases as the discharge progresses, the current internal resistance value in the current internal resistance characteristic also increases, so the above tendency can be accommodated. It is clear that the error between the current internal resistance characteristic and the current true internal resistance characteristic can be reduced satisfactorily.
[0019]
Next, the claim4In the described method, the discharge amount ratio between the virtual discharge amount value corresponding to the current value of the internal resistance on the past internal resistance characteristic and the current value of the discharge amount is obtained, and the discharge amount of the past internal resistance characteristic is obtained. The shaft is compressed by this discharge amount ratio to obtain the current internal resistance characteristic.
In this way, as the internal resistance value in the past internal resistance characteristic increases as the discharge progresses, the current internal resistance value in the current internal resistance characteristic also increases, so the above tendency can be accommodated. It is clear that the error between the current internal resistance characteristic and the current true internal resistance characteristic can be reduced satisfactorily.
[0020]
It is known that the internal resistance corresponding to the increase in the discharge amount increases specifically in the deep discharge state as the deterioration progresses. FIG. 4 schematically shows how the internal resistance increases due to the increased discharge amount as the battery deterioration progresses at the end of discharge. C5 is an initial internal resistance characteristic, and C6 is an internal resistance characteristic in which battery deterioration has progressed.
Therefore, a function for calculating internal resistance corresponding to a specific increase in internal resistance at the time of battery deterioration at the end of discharge and a function for calculating internal resistance in other discharge amount ranges (referred to as an expression function for increasing internal resistance specific to discharge end) The internal resistance characteristics of this time can be calculated from the internal resistance characteristics serving as a past reference.
Claims mentioned above4Internal resistance calculation method describedAccording toThus, a specific increase in internal resistance at the time of battery deterioration at the end of discharge (a phenomenon in which the internal resistance increases more rapidly than in other discharge amount ranges) can be satisfactorily shown.
[0021]
In particular, the expression function for increasing internal resistance specific to the end of discharge is that the internal resistance characteristics gradually change in view of the fact that the internal resistance characteristics gradually change. It is preferable to have resistance characteristics.
In addition, the
[0022]
In addition, the above-mentioned past open circuit voltage characteristics and past internal resistance characteristics can be the initial open circuit voltage characteristics and initial internal resistance characteristics at the initial stage (battery initial stage), which is reversibly restored by charging. It is particularly suitable for open circuit voltage characteristic calculation.
In addition, when the battery is fully charged or when it is discharged from a predetermined discharge amount value to a complete discharge, the open-circuit voltage characteristics and internal resistance characteristics at this time are stored, and then the current open-circuit voltage is based on this. The calculation of the characteristics and the internal resistance characteristics by the above method is also a suitable method for reducing errors.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a battery remaining capacity computing device of the present invention will be described below with reference to the drawings.
[0024]
【Example】
(Device configuration)
FIG. 1 is a block diagram showing an example of a remaining capacity calculation device for a hybrid vehicle according to the present invention.
1 is a battery, 2 is a power transmission means including a rotating electric machine of a hybrid vehicle, and is connected to an engine and a vehicle drive shaft to transfer energy between them and the battery in the form of electric power.
[0025]
The
(Remaining capacity calculation routine 1)
Hereinafter, an example of the remaining capacity calculation process of this embodiment will be described with reference to the flowchart shown in FIG.
[0026]
First, it is checked whether or not discharging is in progress (S10). If discharging is in progress, the process proceeds to S12. If not discharging, the process proceeds to S26.
In S12, the measured internal resistance (current value of the internal resistance) Rm and the measured open circuit voltage (current value of the open circuit voltage) OCVm are calculated from the current values of the measured discharge voltage V and discharge current A, and from the beginning of the discharge to the present. The discharge current A is accumulated until the current value Ahm of the discharge amount is obtained.
[0027]
The measured internal resistance Rm is determined by plotting a number of points defined by the recently detected pair of discharge voltage V and discharge current A on the VA two-dimensional plane to determine a linear approximation line, It is determined by (ΔV / ΔA). Next, the voltage drop is obtained by multiplying the detected discharge current A and the measured internal resistance Rm, and this voltage drop is added to the current value of the discharge voltage V to obtain the measured open circuit voltage OCVm.
[0028]
Next, a Ram map showing the internal resistance characteristics in the current discharge is created (S16). In this embodiment, this Ram map is created by correcting the previous Ram map created at the previous discharge before the previous charging. Of course, the first Ram map is created by modifying the initial Ram map indicating the initial internal resistance characteristics stored in advance.
[0029]
First, the actually measured internal resistance Rm is substituted into the previous Ram map, and a virtual discharge amount value Ahx corresponding to the actually measured internal resistance Rm is obtained on the previous Ram map.
Next, the ratio between the current value Ahm and the virtual value Ahx of the discharge amount Ah is obtained, and an operation for proportionally compressing the axis indicating the discharge amount on the two-dimensional plane showing the previous Ram map (referred to as the discharge amount axis) with this ratio ( (Capacity reduction operation) is performed to obtain the current Ram map.
[0030]
Various methods can be considered as how to create the current Ram map, but each conversion factor of the map showing a predetermined conversion function for each internal resistance value of the Ram map of the past predetermined discharge turn. You can also multiply by a number. Furthermore, the map indicating this conversion function can be rewritten together with the cumulative number of discharges.
Next, a discharge characteristic map at a reference discharge power value is created from the open-circuit voltage map OCVam stored in advance and the Ram map (S18). Here, the discharge characteristic at the reference discharge power value is a characteristic indicating the relationship between the output voltage (discharge voltage) V of the battery and the discharge amount Ah when discharging a predetermined reference discharge power (here 2 kW). It is.
[0031]
More specifically, the discharge voltage V corresponding to the value of the arbitrary discharge amount Ah corresponds to the open-circuit voltage value OCV ′ obtained from the corrected open-circuit voltage characteristic corresponding to the value of the discharge amount Ah and the value of the discharge amount Ah. Correspondingly, it is calculated by the following quadratic function formula from the internal resistance value R ′ obtained from the corrected internal resistance characteristic. Here, W is a reference discharge power value, and A is a discharge current value at this discharge amount Ah.
[0032]
V = OCV′−R ′ · A = OCV′−R ′ · W / V
Next, the remaining capacity is calculated from the discharge characteristics obtained in S18 (S20).
That is, the discharge characteristics are integrated from the current value Ahm of the discharge amount Ah to the discharge amount at which the battery can no longer be discharged with the predetermined reference discharge power, and the remaining capacity capable of discharging the reference discharge power is obtained.
[0033]
Next, it is checked whether or not the discharge is completed and the charging is started (S22). If not, the process jumps to S26, and if so, the discharge amount value Ahx immediately before the start of charging is stored (S24). . This is because the open circuit voltage drop due to the memory effect starts from this discharge amount value Ahx in the next discharge.
Next, it is checked whether or not the discharge has reached the discharge amount value Ahx at the time when the immediately preceding charging operation is started (S26). If not reached, the main circuit returns to the main routine without rewriting the open voltage map OCVam in S28, and if reached, the previous time corresponding to the current value Ahx of the discharge amount Ah at this time on the stored open voltage map OCVam. The difference ΔV between the open-circuit voltage value OCVx of the current and the current actual open-circuit voltage OCVm corresponding to the current value Ahx of the discharge amount Ah is obtained, and the discharge amount range larger than the current value Ahm of the discharge amount Ah of the open-circuit voltage map OCVam stored. The open voltage is slid downward by ΔV (S28). Thereby, the open circuit voltage drop due to the immediately preceding memory effect can be written in the open circuit voltage map OCVam. Of course, the open-circuit voltage map OCVam after the first charge is corrected using the initial Ram map indicating the initial open-circuit voltage characteristics stored in advance.
[0034]
Next, in S10, if not discharging, it is checked whether or not charging is completed (S30). If not, the process returns to the main routine. If charging is completed, this charging operation in the open voltage map OCVam to be stored is performed. Is restored to the value of the initial open-circuit voltage characteristic (that is, the initial open-circuit voltage OCV map) stored in advance. Thereby, the recovery action by the charging operation corresponding to the open circuit voltage drop due to the memory effect can be reflected in the open circuit voltage map OCVam.
(Remaining capacity calculation routine 2)
The remaining capacity calculation process of this embodiment will be described below with reference to the flowcharts shown in FIGS.
[0035]
・ Measurement parameter calculation (step S100),
First, the measured internal resistance Rm and the measured open circuit voltage OCVm are calculated from the current values of the measured discharge voltage V and discharge current A, and the discharge current A from the beginning of the discharge to the present is accumulated to calculate the current value of the discharge amount. Find Ahm.
The measured internal resistance Rm is determined by plotting a number of points defined by the recently detected pair of discharge voltage V and discharge current A on the VA two-dimensional plane to determine a linear approximation line, It is determined by (ΔV / ΔA). Next, the voltage drop is obtained by multiplying the detected discharge current A and the measured internal resistance Rm, and this voltage drop is added to the current value of the discharge voltage V to obtain the measured open circuit voltage OCVm.
[0036]
-Related initial parameter calculation (step S102)
Next, the value of the current value Ahm of the discharge amount described above is substituted into the initial internal resistance characteristic (previously stored as an initial internal resistance map) indicating the relationship between the initial internal resistance Rini and the discharge amount at the initial operation of the battery, The current value of the initial internal resistance Rini on the initial internal resistance characteristic corresponding to the current value Ahm of the discharge amount is obtained, and the current value of the initial internal resistance Rini, the current value of the detected discharge voltage V, and the discharge current A The current value (= Rini · A + V) of the initial open circuit voltage OCVini corresponding to the current value of the initial internal resistance Rini is calculated from the current value.
[0037]
-End of discharge determination (step S106)
Next, in order to correct the internal resistance at the end of the discharge, the current value Qrini of the remaining capacity on the initial characteristics at the present time is calculated as a material for determining whether the discharge is at the end of the discharge (or the latter half of the discharge). The current value Qrini of the remaining capacity on the initial characteristics is a value obtained by subtracting the current value Ahm (Ah) of the discharge amount from the initial full charge capacity Qrfull (Ah) stored in advance.
[0038]
Next, it is checked whether or not the current value Qrini of the remaining capacity on the initial characteristics is less than a predetermined threshold obtained by multiplying the initial full charge capacity Qinifull by a predetermined constant x. If it is less, it is determined that there is a possibility that a specific increase in the internal resistance of the battery may occur at the end of discharge or the second half of discharge, and the process proceeds to the next S110. Therefore, there is no possibility that the internal phenomenon of internal resistance increases, and the correction performed in S114 is unnecessary, and the process jumps to S122. That is, this determination step prevents the internal resistance correction operation performed in S114 from being erroneously performed in a shallow discharge amount region where the specific increase in internal resistance R should not occur at the end of discharge. belongs to. For example, the constant x is a constant less than 1, and is set to 0.5, for example.
[0039]
In S106, it is determined whether or not it is the end of discharge or the latter half of the discharge by comparing the current value Qrini of the remaining capacity on the initial characteristics and the initial full charge capacity Qinifull, but the full charge capacity Ah obtained last time and the current It may be obtained by a similar comparison with the discharge amount Ah, and by a similar comparison between the full charge capacity due to the discharge with the predetermined discharge power at the initial stage and the discharge capacity due to the discharge with the predetermined discharge power so far. You may ask for it.
[0040]
-Determination of increase in internal resistance at the end of discharge (step S110)
Next, the value of the current value Ahm of the discharge amount Ah described above is substituted into the previously determined corrected internal resistance characteristic (characteristic indicating the relationship between the corrected internal resistance Ramend and the discharge amount Ah, also referred to as the previous Ram map). A value of the corrected internal resistance Ramend (referred to as the previous value) Ramfore on the previous Ram map corresponding to the current value Ahm of the discharge amount Ah is obtained.
[0041]
Next, it is examined whether or not the actually measured internal resistance Rm exceeds a predetermined threshold value obtained by multiplying the Rambefore by a predetermined constant y. If it exceeds, a specific phenomenon of increase in internal resistance at the end of discharge occurs. The process proceeds to S112, and if it is below, the increase phenomenon has not occurred, and it is determined that the correction in S114 for compensating for this is not necessary, and the process proceeds to S116. For example, the constant y is a constant exceeding 1.
[0042]
In S110, whether or not the internal resistance sudden increase phenomenon occurs at the end of the discharge is determined by comparing the internal resistance value Rambefore on the previous Ram map corresponding to the current value Ahm of the discharge amount Ah and the measured internal resistance Rm. Even if it is determined whether or not an internal resistance sudden increase phenomenon occurs at the end of discharge by comparing the previous value Rinibefore of the corrected internal resistance Rini on the initial internal resistance characteristic corresponding to the current value Ahm of the discharge amount Ah and the measured internal resistance Rm. Good.
[0043]
-Correction of internal resistance sudden increase phenomenon at the end of discharge 1 (step S112)
Next, the measured internal resistance Rm is substituted into the corrected internal resistance characteristic (previous Ram map) obtained at the previous discharge before the previous charge, and the discharge amount value Ahx corresponding to the measured internal resistance Rm on the previous Ram map. Ask for.
In S112, the measured internal resistance Rm is substituted into the corrected internal resistance characteristic (previous Ram map) obtained at the previous discharge before the previous charge, and the discharge amount corresponding to the measured internal resistance Rm on the previous Ram map is calculated. Although the value Ahx is obtained, the measured internal resistance Rm may be substituted into the initial internal resistance characteristic (initial Ram map), and the discharge amount value Ahx corresponding to the measured internal resistance Rm may be obtained on the initial Ram map.
[0044]
Next, a ratio between the current value Ahm of the discharge amount Ah and the discharge amount value Ahx on the previous Ram map is obtained, and an axis indicating the discharge amount on the two-dimensional plane showing the previous Ram map (discharge amount axis) The current corrected internal resistance characteristic (current Ram map) is obtained by performing an operation of proportionally compressing (capacity decreasing operation).
[0045]
In S114, the discharge amount axis of the previous Ram map is proportionally compressed by the ratio of the current value Ahm of the discharge amount Ah and the discharge amount value Ahx on the previous Ram map. The discharge amount axis of the initial Ram map may be proportionally compressed by the ratio of the value Ahm and the discharge amount value Ahxini on the initial Ram map.
Since the internal resistance sudden increase phenomenon at the end of discharge appears at the end of discharge, the correction of the previous internal resistance characteristic (previous Ram map) by the compression operation of the discharge amount axis detects the internal resistance rapid increase at S110. The discharge amount is larger than the discharge amount value at that time, and the discharge amount axis is not compressed in the discharge amount range before this point.
[0046]
As a result, the sudden increase in internal resistance at the end of discharge is reflected in the previous corrected internal resistance characteristic (previous Ram map) indicating the relationship between the corrected internal resistance Ramend and the discharge amount Ah, and the current corrected internal resistance characteristic (current Ram map) is reflected. Can be sought.
Next, when it is determined in S106 and S110 that the discharge is in a shallow discharge amount range, or when it is determined that no rapid increase in internal resistance has occurred, the current value of the discharge amount Ah on the previous Ram map. The value of the corrected internal resistance Ramend corresponding to Ahm (referred to as the previous value) Rambefor is compared with the actually measured internal resistance Rm, and the actually measured internal resistance Rm is set to a value Rambeforex equivalent to the equivalent internal resistance on the previous Ram map. It is determined whether or not it is larger than the threshold multiplied by the constant z. If it is larger, it is determined that the increase in internal resistance due to battery deterioration has progressed to the extent necessary to correct the previous corrected internal resistance characteristics (previous Ram map). Then, the process proceeds to the next S120, and if it is the following, an increase in internal resistance due to battery deterioration requires correction of the previous corrected internal resistance characteristic (previous Ram map). It is determined that Ruhodo not progressed to jump to S122 in.
Next, the axis (internal resistance axis) indicating the internal resistance of the two-dimensional plane on which the previous Ram map is displayed is the measured internal resistance Rm and the internal resistance on the previous Ram map corresponding to the current value Ahm of the discharge amount Ah. Expansion (resistance value increase) is performed at a ratio to the value Rambefore to obtain the current corrected internal resistance characteristic (current Ram map). That is, the corrected internal resistance value Ram0 on the current Ram map for a certain discharge amount value Ah0 is a ratio of the actually measured internal resistance value Rm0 and the previous internal resistance value Rambefore0 to the discharge amount value Ah0 (Rm0 / Rambefore0). The discharge amount value Ah0 is multiplied by the corrected internal resistance value Ram0 on the previous Ram map.
[0047]
This makes it possible to obtain the current corrected internal resistance characteristic (Ram map) that takes into account the increase in internal resistance due to the deterioration of the battery.
As a result, the increase in internal resistance due to normal battery deterioration can be obtained by extending the internal resistance axis in S120, and the specific increase in internal resistance at the end of discharge can be obtained by compressing the discharge amount axis in S114.
[0048]
In next S122, it is checked whether or not the discharge has reached the discharge amount value Ahx at the start of the immediately preceding charging operation. If not, the process proceeds to S126, and if it has reached, the current discharge amount Ah at the current value Ahx. The voltage difference ΔV between the value of the open circuit voltage OCV (open circuit voltage OCVm at the end of discharge) and the current value Ahx of the current discharge amount Ah on the initial open circuit voltage characteristic is determined as the current value Ahx of the current discharge amount Ah. Are stored in pairs (S124), and the process proceeds to S126. This is for memorizing that the open circuit voltage OCV due to the memory effect decreases by ΔV with respect to the discharge after the discharge amount Ahx at the next discharge.
[0049]
In this step, the open circuit voltage characteristic is corrected.
The open circuit voltage is corrected as follows.
First, in the discharge amount range charged in the immediately preceding charging operation, it is considered that the decrease in the open-circuit voltage OCV due to the memory effect has been eliminated, and the initial open-circuit voltage characteristic is made the current open-circuit voltage characteristic, and this discharge amount range The one or more pairs stored in S124 so far are deleted.
[0050]
Next, in the discharge amount range in which charging was not performed in the immediately preceding charging operation, it is considered that the decrease in the open circuit voltage OCV due to the memory effect remains, and the discharge end stored in S124 so far in this discharge amount range. Based on one or a plurality of pairs of the discharge amount value and the voltage difference ΔV at the time, the voltage difference ΔV in the voltage decreasing direction is indicated by the axis (open voltage axis) indicating the open circuit voltage OCV on the initial open circuit voltage characteristic (OCVini map). Only the sliding operation is performed to obtain the corrected open-circuit voltage characteristics. Thereby, deterioration of the electromotive voltage due to the memory effect can be expressed in the corrected open-circuit voltage characteristic.
[0051]
Note that the slide operation may be performed a plurality of times. For example, consider the point of time when the battery is first discharged from full charge to a discharge amount value of 100 Ah, then fully charged and then discharged to a discharge amount value of 70 Ah, and then fully charged and discharged to a discharge amount value of 50 Ah. At this time, the open circuit voltage OCV is almost restored to the initial open circuit voltage from the discharge amount 0Ah to 70Ah, but the open circuit voltage OCV is decreased from the initial open circuit voltage by the voltage difference ΔV1 at the discharge amount value 70Ah. When the discharge amount value is 100 Ah, the open circuit voltage OCV is reduced from the initial open circuit voltage by the voltage difference ΔV2.
[0052]
Therefore, the current open-circuit voltage characteristic can be determined by level-shifting the initial open-circuit voltage by the voltage difference ΔV1 at the discharge amount value 70Ah and further level-shifting the initial open-circuit voltage by the voltage difference ΔV2 at the discharge amount value 100Ah. .
・ Calculation of discharge characteristics with reference discharge power value (S128)
Next, the discharge characteristic at the reference discharge power value is calculated using the current corrected internal resistance characteristic obtained in S114 or S120 and the current corrected open circuit voltage characteristic obtained in S126. Here, the discharge characteristic at the reference discharge power value is a characteristic indicating the relationship between the output voltage (discharge voltage) V of the battery and the discharge amount Ah when discharging a predetermined reference discharge power (here 2 kW). It is.
[0053]
More specifically, the discharge voltage V corresponding to the value of the arbitrary discharge amount Ah corresponds to the open-circuit voltage value OCV ′ obtained from the corrected open-circuit voltage characteristic corresponding to the value of the discharge amount Ah and the value of the discharge amount Ah. Correspondingly, it is calculated by the following quadratic function formula from the internal resistance value R ′ obtained from the corrected internal resistance characteristic. Here, W is a reference discharge power value, and A is a discharge current value at this discharge amount Ah.
[0054]
V = OCV′−R ′ · A = OCV′−R ′ · W / V
・ Calculation of remaining capacity (S130)
In this step, the discharge characteristic at the predetermined reference discharge power (here 2 kW) obtained in S128 is integrated from the current value Ahm of the discharge amount Ah to the discharge amount at which the battery can no longer be discharged with the predetermined reference discharge power. The remaining capacity capable of discharging the reference discharge power is obtained, and the process returns to the main routine.
(Effect of Example)
In this embodiment described above, since the remaining capacity is obtained from the discharge characteristics obtained based on the internal resistance characteristics and the open circuit voltage characteristics, the remaining capacity can be calculated more accurately than in the past.
[0055]
In other words, in a battery having a memory effect, a decrease in remaining capacity due to the memory effect can be expressed not as an increase in internal resistance but as a decrease in open-circuit voltage, and a decrease in remaining capacity due to battery deterioration is due to an increase in internal resistance rather than a decrease in open-circuit voltage. It can be expressed in the prior art of the applicant's application mentioned above.
What is important here is that the internal resistance varies depending on the discharge amount or the remaining capacity, more precisely, a value that changes in a function depending on the discharge amount or the remaining capacity with respect to the full charge amount. In order to compensate, it is required to compress the discharge amount axis of the discharge characteristic indicating the discharge voltage-discharge capacity by this function. On the other hand, the decrease in the open circuit voltage due to the memory effect is constant with respect to the value of each discharge amount. To compensate for this constant decrease in the open circuit voltage, the discharge voltage minus the discharge capacity is equal to the open circuit voltage decrease in the discharge voltage. It is necessary to perform a level down of the discharge amount axis of the discharge characteristic showing.
[0056]
However, in the above-described prior art of the present applicant's application, the memory of the voltage difference between the discharge voltage before the charge just before the occurrence of a certain discharge amount and the discharge voltage measured this time caused by the same discharge amount is the memory. The ratio between the component due to the effect (voltage component to be level shifted) and the component due to battery deterioration (voltage component to be compensated by discharge amount axial compression) is unknown. Axial compression compensation cannot be performed, which results in a residual capacity calculation error.
[0057]
On the other hand, in this embodiment, by using the internal resistance characteristics and the open circuit voltage OCV characteristics, the internal resistance increase due to the battery deterioration can be accurately handled by the compression of the discharge amount axis or the extension of the internal resistance axis, and Since the open voltage drop due to the memory effect is accurately handled by sliding the open voltage axis, the remaining capacity after the current time is a pair of initial open voltage characteristics and initial internal resistance characteristics, or the previous open voltage characteristics and previous internal resistance characteristics. And the measured open circuit voltage value and internal resistance value can be obtained accurately.
[0058]
Further, when the deterioration of the battery progresses, the phenomenon that the internal resistance rapidly increases at the end of discharge of the battery is determined and dealt with, so that the remaining capacity can be calculated more accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a battery remaining capacity computing device according to the present invention.
FIG. 2 is a schematic characteristic diagram showing a relationship between a discharge amount Ah and a discharge voltage V. FIG.
FIG. 3 is a schematic characteristic diagram showing a relationship between a discharge amount Ah and an internal resistance r.
FIG. 4 is a schematic characteristic diagram showing a relationship between a discharge amount Ah and an open circuit voltage map OCV.
FIG. 5 is a flowchart showing remaining
FIG. 6 is a flowchart showing remaining
FIG. 7 is a flowchart showing remaining
[Explanation of symbols]
1 is battery, 4 is controller, 5 is current sensor
Claims (4)
前記放電電流Ａに基づいて放電量の今回値を算出する放電量算出手段、
前記放電電圧及び放電電流に基づいて電池の内部抵抗の今回値及び開放電圧の今回値を算出する開放電圧算出手段、
前記電池の内部抵抗と放電量との過去の関係を示す内部抵抗特性、及び、前記電池の開放電圧と放電量との過去の関係を示す開放電圧特性を記憶する放電特性記憶手段、
前記内部抵抗の今回値及び開放電圧の今回値並びに前記内部抵抗特性及び開放電圧特性に基づいて残存容量を演算する残存容量演算手段、
を備え、
前記残存容量演算手段は、
前記開放電圧の今回値を変数とする所定の関数で過去の前記開放電圧特性を変形して前記残存容量演算用の今回の前記開放電圧特性を形成し、
前記内部抵抗の今回値を変数とする所定の関数で過去の前記内部抵抗特性を変形して前記残存容量演算用の今回の前記内部抵抗特性を形成し、
前記今回の内部抵抗特性及び前記今回の開放電圧特性に基づいて残存容量を演算し、
前記残存容量演算手段は、
前記今回の内部抵抗特性及び前記今回の開放電圧特性に基づいて求めた前記放電電圧と前記放電量との関係を示す放電特性を、現在の放電量値から所定の放電終了放電量値まで積分して残存容量を演算することを特徴とする電池の残存容量演算装置。 Detecting means for detecting a discharge voltage and a discharge current of a chargeable / dischargeable battery;
A discharge amount calculating means for calculating a current value of the discharge amount based on the discharge current A;
An open-circuit voltage calculating means for calculating a current value of the internal resistance of the battery and a current value of the open-circuit voltage based on the discharge voltage and the discharge current;
A discharge characteristic storage means for storing an internal resistance characteristic indicating a past relationship between the internal resistance of the battery and a discharge amount, and an open circuit voltage characteristic indicating a past relationship between the open circuit voltage and the discharge amount of the battery;
A remaining capacity calculating means for calculating a remaining capacity based on the current value of the internal resistance and the current value of the open circuit voltage and the internal resistance characteristics and the open circuit voltage characteristics;
With
The remaining capacity calculating means includes
The previous open-circuit voltage characteristic is transformed by a predetermined function having the current value of the open-circuit voltage as a variable to form the current open-circuit voltage characteristic for the remaining capacity calculation,
The previous internal resistance characteristic is transformed by a predetermined function having the current value of the internal resistance as a variable to form the current internal resistance characteristic for the remaining capacity calculation,
Calculate the remaining capacity based on the current internal resistance characteristics and the current open circuit voltage characteristics,
The remaining capacity calculating means includes
The discharge characteristic indicating the relationship between the discharge voltage and the discharge amount obtained based on the current internal resistance characteristic and the current open circuit voltage characteristic is integrated from the current discharge amount value to a predetermined discharge end discharge amount value. And calculating a remaining capacity of the battery.
前記放電電流Ａに基づいて放電量の今回値を算出する放電量算出手段、
前記放電電圧及び放電電流に基づいて電池の内部抵抗の今回値及び開放電圧の今回値を算出する開放電圧算出手段、
前記電池の内部抵抗と放電量との過去の関係を示す内部抵抗特性、及び、前記電池の開放電圧と放電量との過去の関係を示す開放電圧特性を記憶する放電特性記憶手段、
前記内部抵抗の今回値及び開放電圧の今回値並びに前記内部抵抗特性及び開放電圧特性に基づいて残存容量を演算する残存容量演算手段、
を備え、
前記残存容量演算手段は、
前記開放電圧の今回値を変数とする所定の関数で過去の前記開放電圧特性を変形して前記残存容量演算用の今回の前記開放電圧特性を形成し、
前記内部抵抗の今回値を変数とする所定の関数で過去の前記内部抵抗特性を変形して前記残存容量演算用の今回の前記内部抵抗特性を形成し、
前記今回の内部抵抗特性及び前記今回の開放電圧特性に基づいて残存容量を演算し、
前記残存容量演算手段は、
前記過去の開放電圧特性上で前記放電量の今回値に対応する仮想の開放電圧値と前記開放電圧の今回値との間の電圧差を、メモリ効果の量が異なる放電量範囲ごとにそれぞれ記憶し、
前記放電量範囲ごとに前記電圧差だけ前記過去の開放電圧特性をスライドして前記今回の開放電圧特性を形成することを特徴とする電池の残存容量演算装置。 Detecting means for detecting a discharge voltage and a discharge current of a chargeable / dischargeable battery;
A discharge amount calculating means for calculating a current value of the discharge amount based on the discharge current A;
An open-circuit voltage calculating means for calculating a current value of the internal resistance of the battery and a current value of the open-circuit voltage based on the discharge voltage and the discharge current;
A discharge characteristic storage means for storing an internal resistance characteristic indicating a past relationship between the internal resistance of the battery and a discharge amount, and an open circuit voltage characteristic indicating a past relationship between the open circuit voltage and the discharge amount of the battery;
A remaining capacity calculating means for calculating a remaining capacity based on the current value of the internal resistance and the current value of the open circuit voltage and the internal resistance characteristics and the open circuit voltage characteristics;
With
The remaining capacity calculating means includes
The previous open-circuit voltage characteristic is transformed by a predetermined function having the current value of the open-circuit voltage as a variable to form the current open-circuit voltage characteristic for the remaining capacity calculation,
The previous internal resistance characteristic is transformed by a predetermined function having the current value of the internal resistance as a variable to form the current internal resistance characteristic for the remaining capacity calculation,
Calculate the remaining capacity based on the current internal resistance characteristics and the current open circuit voltage characteristics,
The remaining capacity calculating means includes
The voltage difference between the current value of the virtual open circuit voltage value and the open-circuit voltage corresponding to the current value of the discharge amount on the open-circuit voltage characteristics of the past, respectively for each different amounts discharge weight range of memory effect Remember,
A battery remaining capacity calculation device characterized in that the current open circuit voltage characteristic is formed by sliding the past open circuit voltage characteristic by the voltage difference for each discharge amount range.
前記残存容量演算手段は、
前記過去の内部抵抗特性上で前記放電量の今回値に対応する仮想の内部抵抗値と前記内部抵抗の今回値との間の抵抗比を求め、前記過去の内部抵抗特性を前記抵抗比だけ伸長して前記今回の内部抵抗特性を形成することを特徴とする電池の残存容量演算装置。 In the battery remaining capacity calculation device according to claim 1 ,
The remaining capacity calculating means includes
A resistance ratio between a virtual internal resistance value corresponding to the current value of the discharge amount on the past internal resistance characteristic and the current value of the internal resistance is obtained, and the past internal resistance characteristic is extended by the resistance ratio. Then, the remaining capacity calculation device for a battery is characterized in that the internal resistance characteristic of this time is formed .
前記放電電流Ａに基づいて放電量の今回値を算出する放電量算出手段、
前記放電電圧及び放電電流に基づいて電池の内部抵抗の今回値及び開放電圧の今回値を算出する開放電圧算出手段、
前記電池の内部抵抗と放電量との過去の関係を示す内部抵抗特性、及び、前記電池の開放電圧と放電量との過去の関係を示す開放電圧特性を記憶する放電特性記憶手段、
前記内部抵抗の今回値及び開放電圧の今回値並びに前記内部抵抗特性及び開放電圧特性に基づいて残存容量を演算する残存容量演算手段、
を備え、
前記残存容量演算手段は、
前記開放電圧の今回値を変数とする所定の関数で過去の前記開放電圧特性を変形して前記残存容量演算用の今回の前記開放電圧特性を形成し、
前記内部抵抗の今回値を変数とする所定の関数で過去の前記内部抵抗特性を変形して前記残存容量演算用の今回の前記内部抵抗特性を形成し、
前記今回の内部抵抗特性及び前記今回の開放電圧特性に基づいて残存容量を演算し、
前記残存容量演算手段は、
前記過去の内部抵抗特性上で前記内部抵抗の今回値に対応する仮想の放電量値と前記放電量の今回値との間の放電量比を求め、前記過去の内部抵抗特性を前記放電量比だけ圧縮して前記今回の内部抵抗特性を形成し、
前記残存容量演算手段は、
前記放電が深く、かつ、前記内部抵抗の今回値が所定値より大きい場合に、前記放電量比に基づく前記圧縮により前記今回の内部抵抗特性を求めることを特徴とする電池の残存容量演算装置。 Detecting means for detecting a discharge voltage and a discharge current of a chargeable / dischargeable battery;
A discharge amount calculating means for calculating a current value of the discharge amount based on the discharge current A;
An open-circuit voltage calculating means for calculating a current value of the internal resistance of the battery and a current value of the open-circuit voltage based on the discharge voltage and the discharge current;
A discharge characteristic storage means for storing an internal resistance characteristic indicating a past relationship between the internal resistance of the battery and a discharge amount, and an open circuit voltage characteristic indicating a past relationship between the open circuit voltage and the discharge amount of the battery;
A remaining capacity calculating means for calculating a remaining capacity based on the current value of the internal resistance and the current value of the open circuit voltage and the internal resistance characteristics and the open circuit voltage characteristics;
With
The remaining capacity calculating means includes
The previous open-circuit voltage characteristic is transformed by a predetermined function having the current value of the open-circuit voltage as a variable to form the current open-circuit voltage characteristic for the remaining capacity calculation,
The previous internal resistance characteristic is transformed by a predetermined function having the current value of the internal resistance as a variable to form the current internal resistance characteristic for the remaining capacity calculation,
Calculate the remaining capacity based on the current internal resistance characteristics and the current open circuit voltage characteristics,
The remaining capacity calculating means includes
On the past internal resistance characteristic, a discharge amount ratio between a virtual discharge amount value corresponding to the current value of the internal resistance and the current value of the discharge amount is obtained, and the past internal resistance characteristic is calculated as the discharge amount ratio. Only to compress the internal resistance characteristics of this time,
The remaining capacity calculating means includes
The battery remaining capacity calculation device characterized in that the current internal resistance characteristic is obtained by the compression based on the discharge amount ratio when the discharge is deep and the current value of the internal resistance is larger than a predetermined value.
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1998
- 1998-11-04 JP JP31364498A patent/JP4110639B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020002012A1 (en) * | 2018-06-26 | 2020-01-02 | Johnson Controls Autobatterie Gmbh & Co. Kgaa | Method for estimating a state of an electrical energy-storage system, and system for determining a remaining capacitance of an electrical energy-storage system |
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