JP3551084B2

JP3551084B2 - Secondary battery state management method and battery pack using this method

Info

Publication number: JP3551084B2
Application number: JP17049099A
Authority: JP
Inventors: 隆永岡
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-06-17
Filing date: 1999-06-17
Publication date: 2004-08-04
Anticipated expiration: 2019-06-17
Also published as: JP2001008375A

Description

【０００１】
【発明の属する技術分野】
本発明は、二次電池、特にニッケル−水素電池等の正極にニッケルを用いた二次電池に対して、放充電容量及び二次電池が接続された充放電経路に印加される電流の変化から充放電の繰り返し回数からリフレッシュ充放電の制御を行う二次電池の状態管理方法及びこれを用いた電池パックに関する。
【０００２】
【従来の技術】
近年、ノートパソコンやカムコーダー等の携帯機器、モーターによる動力を補助として使用するパワーアシスト機構を備えた車両の電源として、充放電可能な電池を収容した電池パックが使用されている。電池パックには、電池の充放電状態の制御、異常時に電池の保護を行う制御手段が設けられている。
【０００３】
前記の電池として、ニッケル−カドニウム電池や、ニッケル−水素電池等の正極にニッケルを用いた二次電池（以下、二次電池とする）を使用する場合には、放電深度の浅い充放電を繰り返した際に放電容量が低下する現象、所謂メモリー効果が生ずる。このメモリー効果の発生を抑制するために、所定回数の充放電が繰り返された後、放電深度の深い放電を行う方法が、前記二次電池を用いた機器に用いられている。この様な機器においては、制御手段にて充放電回数の計数を行い、この回数が予め定められた値に達した場合に、リフレッシュ充放電がなされる構成が知られている（例えば、特開平６−１０５４７５号公報に記載）。
【０００４】
充放電回数の計数は、充電が完了した状態にある二次電池から予め定めた容量値を下回るまで放電がなされた後、満充電状態に達するまで充電がなされた時に、１サイクルの充放電が終了したとして、電池パックに記憶している使用開始時からの計数値に１カウントを加える。このような計数機能を有する装置の回路の一例を、図３に示す。
【０００５】
図３において、電池パック１は、複数個の二次電池セルを接続した電池ブロック３、充放電回数の計測を行う制御部７を有している。電池パック１が本体装置２に装着された際に、二次電池３に供給される充電電気量、及び電池ブロック３から本体装置２に供給する放電電気量は、電流検出抵抗８によって検出される。制御部７は、電池ブロック３が接続された充放電経路に印加される充電、放電電流によって電流検出抵抗８の両端に生ずる電位差を変換することで算出する。さらに、この電位差の正負を判断することによって、充放電検出回路１１が電池ブロック３に印加される電流が、充電電流であるか、放電電流であるかを検出する。例えば二次電池３が放電状態にあれば、放電電流を計測し、放電電流積算回路３０にて放電電流値を積算することで放電電気量の算出を行う。得られた放電電気量は、放電容量比較回路３２にて、放電容量設定回路３１に予め設定された放電容量値と比較される。放電電気量が設定放電容量を上回り、且つ二次電池３が放電状態から充電状態へと切り換えられた際に、充放電回数カウンタ１４に記憶された計数値に１カウントを増加させると共に、放電電流積算回路３０に積算された放電電気量の値をリセットする。充電状態が継続し、二次電池３が満充電状態となった後、再度放電を開始すると、上記過程を繰り返すことで、充放電回数の計数が行われるものである。
【０００６】
前記のリフレッシュ充放電は、通信回路１７から送出された充放電回数を受けて、装置本体制御部６にて制御される。この充放電を行う際、制御部６は本体負荷５に対して並列に配置されたリフレッシュ放電負荷２８側にスイッチ６１及び６２を切り換えて電池ブロック３に残存する放電容量の放電を行う。放電の容量は、電池の初期状態における放電容量、及び深度の深い放電を行った際における放電電圧の変化から求めた放電容量をもとにして決定される。放電が終了すると、再度スイッチを切り換え、電池ブロック３の充電を実施する。
【０００７】
【発明が解決しようとする課題】
最近では、二次電池に対する充放電制御の傾向として、無停電電源のバックアップ用電源では、電池の自己放電分のみを間欠充電する制御方法や、ノート型ＰＣ等のＡＣアダプタを常時接続して使用する構成では、電池の容量減少分を暫時充電により補う制御方法が主流となっており、完全放電を行う前に充電がなされてしまう。また、車両の動力補助に使用される場合では、電池の寿命を延ばす為、さらに電池の発熱による劣化の加速を抑制する為に、浅い充放電制御の方が好ましいとされている。このような背景のため、放電深度の浅い充放電を繰り返す充電制御方法によってメモリー効果の発生が助長されている。このような背景を有するにもかかわらず、リフレッシュ充電が施される回数は、機器の使用様態に対応するために少なくなってしまう。
【０００８】
一方、二次電池の放電容量は、電池の劣化により次第に減少する。劣化の進行程度は、充放電回数に加え、使用される環境の温度条件にも大きく影響される。例えば、図４に示すように２０℃の温度環境において使用される二次電池に比べ、４０℃の高温環境下で使用される電池の寿命は短くなってしまう。従って、高温環境下で使用される二次電池は、劣化の進行が加速される。特に前記のような二次電池は、無停電電源のバックアップ用電源、ノート型ＰＣの電源、車両用の電源を主たる用途としており、これらの用途では機器内部での発熱量の増加、屋外での使用に伴う過大な温度変化等により、使用される環境の温度による影響が大きい。
【０００９】
リフレッシュ充放電における放電の深度は電池の放電容量から設定される。二次電池の放電容量は劣化の進行によって減少しており、深度の深い放電を行うことで初期の容量に対する補正を実施し、放電容量の精度を確保している。然しながら、前記のような充放電制御が設定されている機器においては、深度の浅い放電のみが繰り返されており、メモリ効果を生じやすい使用条件にある。而して、これらの機器に対してリフレッシュ充電を定期的に実施し、放電容量の補正を行うのは、使用様態を考慮すると非常に困難である。そこで、放電容量の補正がなされず、初期状態での放電容量に基づきリフレッシュ充放電時の放電深度を設定した場合には、二次電池の放電可能な容量を越える容量を放電し、過放電状態に陥る可能性があるという問題点を有している。
【００１０】
前記のような問題点に対して、充放電の繰り返し回数から二次電池の劣化程度を推定し、初期の容量に対する補正を行うことで、リフレッシュ充電時における過放電の発生を抑制する構成が考えられる。前記の機器は、使用される環境の温度変化が激しく、且つ高温環境下において劣化が加速されており、放電容量の正確な推定は非常に困難である。このため、充放電の繰り返し回数のみから放電容量を算出し、リフレッシュ放電を実施する構成を採用した場合であっても、前記と同様の問題点が生じてしまう。
【００１１】
本発明は、前記の各問題点に鑑み、二次電池のリフレッシュ充放電を行う際の放電深度を、電池の劣化程度に応じて的確に設定することが可能となる二次電池の状態管理装置及びこれを用いた電池パックを提供することを目的とする。
【００１２】
【課題を解決するための手段】
上記目的を達成するために本発明の二次電池の状態管理方法及びこの方法を用いた電池パックは、充放電可能な二次電池に対し、所定の放電容量以下になるまでの放電と、満充電状態あるいは予め定められた容量に達するまでの充電を１サイクルとし、この１サイクル中における電池温度の変化状況に応じて設定された係数を乗じた値を、充放電の繰り返し回数に加えることで充放電の繰り返し回数の累積を行い、累積値からリフレッシュ充放電の実施時期、及びこの累積値に対応する二次電池の放電容量の推定を行っており、さらに二次電池への充放電電流量から残存容量を算出し、これらを併せてリフレッシュ充放電の条件設定を行うものである。
【００１３】
本発明の構成によれば、電池の周辺温度に対応して充放電回数の計数値が増加することとなり、通常の温度条件から外れた環境下、すなわち高温や低温の環境下において使用され、劣化の進行が加速される二次電池であっても、劣化状態を考慮してリフレッシュ充放電の条件設定がなされるために、二次電池が過充電、過放電等の不適切な状態に陥ることがない。
【００１４】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００１５】
本願の請求項１に記載の発明は、充放電可能な二次電池への充電電流、及び二次電池からの放電電流を測定し、二次電池の充放電回数を計数し、累積された回数が所定値に達した場合にリフレッシュ充放電を行う二次電池の状態管理方法に関するものである。
【００１６】
この二次電池の状態管理方法は、充放電経路に印加される電流の方向から充電電流と放電電流との判別を行い、これと同時に充放電の各電流量を測定することで、二次電池へ充電電流及び放電電流の両方が印加された際に、好ましくは二次電池の残存容量が第一の容量以下に達するまで放電された後、第二の容量に達するまで充電が施された際に１サイクルの充放電がなされたとして、このサイクル終了後における二次電池の残存容量の検出を行う。
【００１７】
同時に前記の状態管理方法は、二次電池の周囲温度を測定し、充放電サイクル期間中において周囲温度を平均化し、この温度に対応する予め設定された充放電回数の補正係数を選択し、この補正係数を乗じた温度補正済みのサイクル数を、充放電回数の累積値に加算して新たな充放電回数の累積回数を求め、二次電池の周囲温度の条件が反映された充放電回数の累積値を算出する。
【００１８】
更に前記の状態管理方法は、充放電回数の累積値が予め定められた設定値に達した際に、リフレッシュ充放電を実施する。この充放電における充電及び放電の各条件は、温度条件が反映された充放電回数の累積値を参照して、二次電池の充放電回数に対応する放電容量が示された関係式から前記の累積値における二次電池の放電容量を演算し、リフレッシュ充放電における放電量及び充電量の条件設定を行う。すなわち、電池の充放電回数から得られた放電容量と、残存容量からリフレッシュ充放電時の放電量を設定し、この放電量と放電容量からリフレッシュ充放電時の充電量を設定する。
【００１９】
このように本発明の二次電池の状態管理方法によれば、リフレッシュ充放電時における電池の劣化状態を反映した電池の放電容量の推定を行い、これを参照して二次電池に供給される充電電流量、放電電流の積算値を求めることで残存容量を算出することでリフレッシュ充放電における放電、充電の各条件設定がなされることから、二次電池へ悪影響を与えることのないリフレッシュ充放電を実施することが可能となる。特に、放電時においては、二次電池の残存容量と、劣化状態を反映した電池の放電容量から放電量を算出するために、二次電池が過充電状態に陥ることがない。また、充電時においても、前記の放電条件を基準として、充電条件を設定するために過充電状態となることもない。
【００２０】
また、リフレッシュ充放電時を実施する段階において、前記の条件に従って二次電池の充放電状態を管理することに併せて、二次電池の放電電圧値及び充電電圧値による充放電状態の管理を行うことで、二次電池の充放電電圧のみから制御を行う周知のリフレッシュ充放電方法に比べて充放電制御の正確性が大幅に向上する。
【００２１】
前記の請求項１に係る二次電池の状態管理方法に加えて、二次電池の周囲温度と、これに対応する自己放電量の関係式から、１サイクル中の自己放電量を演算することで二次電池の自己放電量を算出し、充放電電流を積算した残存容量からこの自己放電量を減算した残存容量を求め、この残存容量を用いてリフレッシュ充放電時における放電、充電の各条件設定を行うようにしてもよい。この条件設定にすれば、自己放電量の大きい温度環境下にて使用される場合、また充放電のサイクルが長期間にわたり、自己放電による容量減少が顕著になる使用様態であっても、二次電池がおかれる環境温度の変動による自己放電量の相違も考慮した正確なリフレッシュ充放電の条件設定が行える。
【００２２】
一方、本願の請求項３に記載の発明は、充放電可能な二次電池に対し、充放電経路を介して接続されたリフレッシュ充放電手段、及び充電電源に接続され、所定回数の充放電が繰り返された際にリフレッシュ充放電を実施する電池パックに関する。
【００２３】
この電池パックは、二次電池と、充放電経路に印加される電流の方向から充放電回数を検出すると共に、印加される充電電流量、及び放電電流量から二次電池の放電可能な残存容量を検出する制御手段と、二次電池の表面に接触もしくは臨んだ状態に配され、二次電池の周囲温度を検出する温度検出手段と、二次電池の充放電回数に対応する放電容量が記憶された記憶手段と、充放電回数が所定回数に達した際にリフレッシュ放電手段へリフレッシュ充放電を要求するリフレッシュ充放電要求手段とを備える。
【００２４】
ここにおいて制御手段は、充放電経路に介装された電流検出抵抗から二次電池に印加される充電電流量、放電電流量を測定する充放電検出回路、温度検出手段の検出値から１サイクル中における二次電池の平均化された周囲温度の算出を行い、この温度に対応する予め設定された充放電回数の補正係数を選択する温度補正回路、前回までの充放電回数の累積値に、補正係数を乗じた回数増加値を加算することで新たな充放電回数の累積値を算出する充放電繰り返し回数計測回路、１サイクル中の充電電流量、及び放電電流量から二次電池の残存容量を算出する電流積算回路から構成されている。
【００２５】
さらに、前記の電池パックは、充放電回数がリフレッシュ充放電要求手段に設定された値に達した際に、記憶手段は、温度補正された充放電回数と放電容量との関係を示す関係式を参照し、充放電回数に対応する二次電池の放電容量を演算する。
【００２６】
本発明に係る電池パックは、リフレッシュ充放電手段へ前記の各手段によって検出及び演算された充放電回数、残存容量及び放電容量を伝達し、リフレッシュ放電時の放電量を放電容量と残存容量から設定し、且つ充電量を前記の放電量と放電容量から設定することを特徴とする。
【００２７】
請求項３に記載の構成によれば、電池の充放電回数及び電池の周囲温度を測定することで、電池の置かれる環境温度の影響を反映した電池の劣化状態を推定する。そして、リフレッシュ充放電の充放電条件が、前記の劣化状態を考慮し、さらに二次電池への充放電電流から算出された二次電池の残存容量を参照して設定される。このため電池電圧のみから電池のリフレッシュ充放電を制御する周知のリフレッシュ充放電回路に比較して、リフレッシュ放電時における過放電状態、充電時における過充電状態に陥ることがなく、二次電池の寿命に悪影響を与えることがない。
【００２８】
さらに、充放電回数のみからリフレッシュ充放電の実施時期を制御する図３に示す周知の構成を有するリフレッシュ充放電回路に比して、本発明に係るリフレッシュ充放電回路は、電池の環境温度を考慮している。例えば、温度が高い場合にはメモリー効果の発生確率が高いとして、１サイクルの充放電に対してその累積値を少なくとも２サイクル増加させており、実際の充放電の繰り返し回数に比べて累積値は高くなる。このため、高温環境下で使用される二次電池では、リフレッシュ充放電を実施する時期が通常の温度環境下にて使用される電池に比べて、早期にリフレッシュ充放電がなされる。
【００２９】
一方、本発明の電池パックの回路は、電池周囲温度を測定する温度検出手段を設け、周囲温度に応じて１サイクル当たりの回数増加値に反映する構成としており、さらに繰り返し回数と電池の放電容量との関係を記憶する記憶手段を追加するのみであり、周知の充放電の繰り返し回数のみからリフレッシュ充放電を実施する周知のリフレッシュ充放電回路に比べて構成の複雑化を招かない。
【００３０】
さらにまた本願の請求項５に記載の発明は、充放電可能な二次電池に対し、充放電経路を介して接続されたリフレッシュ充放電手段、及び充電電源に接続され、二次電池の残存容量及び充電回数からリフレッシュ充放電の実施時期を判断する電池パックに関する。
【００３１】
この電池パックは、二次電池と、充放電経路に印加される電流の方向から充放電回数を検出すると共に、二次電池に印加される充電、放電の各電流量及び二次電池の自己放電量から残存容量を検出する制御手段と、二次電池の残存容量が予め定められた容量値を下回った際に、充電器電源に充電を要求し、この充電の回数を累積する残存容量比較手段と、二次電池の表面に接触もしくは臨んだ状態に配され、二次電池の周囲温度を検出する温度検出手段と、二次電池に対する充電の実施回数と放電容量との関係が記憶された記憶手段と、リフレッシュ放電手段へリフレッシュ充放電を要求するリフレッシュ充放電要求手段とを備える。
【００３２】
さらに前記の制御手段の詳細な構成としては、充放電経路に介装された電流検出抵抗から二次電池への充電電流量、放電電流量を測定する充放電検出回路、温度検出手段の検出値から二次電池の周囲温度の平均化を行い、平均の周囲温度に対応する予め設定された充放電回数の補正係数を選択する温度補正回路、前回までの充放電回数の累積値、及び該補正係数から新たな累積値を演算することで充放電回数を算出する充放電繰り返し回数計測回路、充電電流量及び放電電流量を積算する電流積算回路、二次電池の周囲温度に対応する自己放電量が設定されており、二次電池の平均の周囲温度に対応する自己放電量を選択し、電流積算回路にて算出した残存容量から自己放電量を減算して残存容量を求める自己放電演算回路とされている。
【００３３】
そして、前記の構成を有する請求項５に係る電池パックは、充電回数がリフレッシュ充放電要求手段に設定された値に達した際に、記憶手段は温度補正された充電回数に対応する該二次電池の放電容量を演算し、リフレッシュ充放電手段に、この放電容量と、自己放電に対する補正が施された残存容量からリフレッシュ充放電時の放電量を設定し、且つこの放電量と記憶手段に設定された放電容量からリフレッシュ充放電時の充電量を設定することを特徴とする。
【００３４】
この構成によれば、自己放電量に相当する電流量の補充電のみが繰り返される電池パックであっても、充電回数及び自己放電量を推定することで、リフレッシュ充放電の実施時期及びその条件が設定される。さらに、放電深度の深い充放電が繰り返される使用様態とする電池パックであっても、充電の繰り返し回数及び電池の周囲温度に加え、電池の自己放電量を考慮したリフレッシュ充放電の実施条件が設定され、メモリー効果の発生が抑制される。
【００３５】
【実施例】
以下、本発明の実施例について、図面を参照しながら説明する。尚、本実施例は、本発明の構成の一例を示すものであり、その範囲を限定するものではない。また、従来例と同一の機能を果たす構成要素については、同一の番号を付し、詳細な説明は省略する。
【００３６】
（実施例１）
図１は、本発明の第１の実施例における充放電のリフレッシュ充放電機能を有する電池パック及び本体装置の構成を示すブロック図である。図１において、電池パック１は、複数の二次電池セルが直列接続された電池ブロック３、制御部７を内蔵しており、負荷５を具備した本体装置２に接続される。電池パック１と本体装置との電気的接続は、端子４１から端子４６でなされる。
【００３７】
電池パック１の内部にて、電池ブロック３と端子４２及び端子４３とを接続する充放電経路中には、電流検出抵抗８が介装されている。電流検出抵抗８は、電池ブロック３に供給される充電電流、電池ブロック３から本体負荷５、及びリフレッシュ充放電時にリフレッシュ放電負荷２８へと供給する放電電流の測定を行い、各電流の値は検出抵抗６の両端の電位差として表わされる。制御部７は、アナログ値にて測定された値をデジタル値に変換するＡＤ変換回路１０１〜１０３をはじめとする各回路から構成される。
【００３８】
本体装置２は、端子４４及び端子４５を介して電池パック１側の充放電経路に接続され、充放電の各電流の需給を行う。さらに、本体装置２側の充放電経路には、スイッチ６１及びスイッチ６２が介装されており、これらのスイッチを切り換えることで、電池ブロック３から本体負荷５への電力供給、充電電源９による充電、そしてリフレッシュ放電負荷２８によるリフレッシュ放電がなされる。また、充電経路に付加される電圧は、電圧検出回路２６によって検出される。装置本体制御回路６は、前記の電圧値に加え、電池パック１から送出される各種データをもとにして、スイッチ６１、６２を切り換え、電池ブロック３の充電、本体負荷５への電力供給及びリフレッシュ充放電の実施を制御する。
【００３９】
次に制御回路７を含む電池パック１の詳細な構成について説明する。充放電検出回路１１は、電流検出抵抗の両端に生ずる電位差から充電、放電の判別、及び電池ブロック３に印加される充放電の各電流値を測定しており、充放電状態の変化は、回数計測回路１２へと出力され、充放電の回数が計数される。温度センサー１３は電池ブロック３に隣接して配置されており、電池ブロック３の周囲温度を測定している。測定された電池温度は、温度補正テーブル回路１４へ出力される。温度補正テーブル回路１４は、電池の充放電期間中の温度変化を記憶し、これをもとにして温度による電池の劣化度合いを補正する。数値補正回路１５は、温度補正テーブル回路１４及び回数計測回路１２の出力結果をもとに、充放電の回数に対する補正を行っており、充放電繰り返し回数カウンタ１６に記憶される。この記憶された充放電の繰り返し回数は、通信回路１７を介して本体装置２へ伝達されると共に、数値設定回路１９及び数値比較回路２０からなるリフレッシュ充放電要求手段１８に出力される。
【００４０】
数値設定回路１９は、リフレッシュ充放電を実施する充放電の繰り返し回数を設定しており、この回数の設定は、電池パック１が接続される本体装置２の使用様態に応じて設定される。数値比較回路２０は、設定された値に電池ブロック３の充放電の回数が達した際に、リフレッシュ充放電を要求する信号を出力する。
【００４１】
充放電検出回路１１から出力される充放電の各電流値は、電流積算回路２１において積算される。また、温度センサー１３によって測定された電池ブロック３における温度は、自己放電量演算回路２２へ出力され、回路１１において温度条件による自己放電量を演算する。自己放電補正回路２２は、充放電の繰り返しによる放電容量の変動に加え、温度変化による自己放電量を加味して、電池ブロック３における残存容量を算出する。
【００４２】
記憶装置２９には、電池ブロック３を構成する二次電池の電池特性、少なくとも通常の温度環境下における充放電の繰り返しに伴う放電容量の推移が記憶されている。この放電容量の推移は、例えば図４に示したような充放電の繰り返し回数と、放電容量とを記憶している。これにより、充放電の繰り返しによる電池の劣化に起因する放電容量の変化に対し、充放電の回数から通常の温度環境下における電池の放電容量を推定できる。
【００４３】
次に、本実施例における回路の動作を説明する。
【００４４】
電流検出抵抗６の両端に生ずる電位差は、ＡＤ変換回路１０１によりデジタルデータに変換されており、このデジタルデータから放電状態にあるか、充電状態にあるかを充放電検出回路１１で検出する。回数計測回路１２は、放電から充電に切り替わった時に１回の回数を計測する。
【００４５】
温度センサー１３にて検出された温度データは、温度補正テーブル回路１４において平均値化を行い、補正値変換がなされる。この補正値の変換は、電池の温度による充放電の繰り返し回数の補正を行うためになされる。例えば、平均温度が高い場合には電池の劣化が加速されており、１回の充放電がなされた際に、温度による劣化加速を考慮した充放電の回数を増加させる補正値を出力する。温度補正テーブル回路１４から出力される補正値と、回数計測回路１２における計数値とに基づいて、数値補正回路１５は、充放電の繰り返し回数を演算する。この時、回数計測回路１２で出力された回数の増加値は、補正値を加算、乗算することで演算される。さらに、温度補正された回数の増加値は、充放電繰り返し回数カウンタ１６に入力され、回数の増加値にしたがったカウントアップがなされ、ここにおいて充放電繰り返し回数が記憶される。これにより、例えば高温環境下におかれる電池であっても、温度による劣化加速が反映された充放電の繰り返し回数値が算出され、この繰り返し回数のみから電池の劣化程度を判断することが可能となる。
【００４６】
前記カウンタ１６に記憶された充放電の繰り返し回数は、リフレッシュ充放電要求手段１８に入力される。カウンタ１６より出力される充放電回数は、数値比較回路２０に入力され、数値設定回路に設定されている数値と比較される。前記したように数値設定回路１９は、リフレッシュ充放電を行なうべき充放電の累積回数を記憶しており、数値比較回路２０は、温度補正された充放電の繰り返し回数が予め設定した累積回数に達した時に、リフレッシュ充放電要求信号を出力する。
【００４７】
前記の充放電検出回路１１は、充放電の切り替えの検出に加えて、充放電経路に印加される充電、及び放電の各電流量も測定を行っている。充放電電流検出回路１１から出力される充放電電流データは、電流積算回路２１に入力され、電池ブロック３の残存容量を算出すべく積算演算が行なわれる。この演算は、電流積算回路２１に設定された初期状態における放電容量に対して、放電時には放電に伴う電流量を前記の放電容量から減算し、放電から充電に転じた後には充電に伴って電池ブロック３に供給された電流量を前記の減算された放電容量に加算する。
【００４８】
さらに、前記の放電容量に対して、自己放電による容量減少の相当分を、前記の過程にて演算された放電容量に反映する。自己放電は、電池パック１がおかれる環境温度によって変動することから、自己放電量演算回路２３は、温度センサー１３によって検出された温度を取り込み、得られた温度のデータに基づいて、自己放電量を演算する。尚、本実施例では自己放電量の補正は、電池温度から算出する構成としているが、電池温度に加え、電池ブロック３に対して充放電電流の需給が行われていない放置期間も考慮して、自己放電量を演算することで、電池ブロック３の放電容量の検出精度は一層向上する。自己放電補正回路２２は、電流積算データから自己放電量を減算補正し、自己放電減算補正された電流積算データを出力する。
【００４９】
充放電繰り返し回数カウンタ１６から出力された充放電の繰り返し回数、リフレッシュ充放電要求手段から出力される要求信号、及び自己放電補正回路から出力された電池ブロック３の放電容量、さらに記憶回路に設定された電池の劣化による放電容量の状況に関する各データは、通信回路１７にてシリアル変換され、本体装置２へ送出される。
【００５０】
本体装置２では、電池パック１から送出されたリフレッシュ充放電の要求信号によりリフレッシュ充放電を行う。本体装置制御回路６は、通信回路１７から受け取ったデータをもとにして、リフレッシュ充放電の充電、放電の各条件を設定し、この充放電を実施する。一連のリフレッシュ充放電の動作は、本体制御回路６はリフレッシュ充放電要求手段からの要求信号により開始される。
【００５１】
次に、充放電の繰り返し回数、及び記憶手段に記憶されている充放電回数から電池ブロック３を構成する各二次電池の劣化状態を推定し、この劣化の程度に対応した電池の放電容量に関するデータを得る。前記のように充放電の繰り返し回数は、環境温度による電池の劣化の加速状態を反映した値となっており、記憶回路に設定された充放電の繰り返し回数に対応する放電容量をもとめることで、劣化に伴う放電容量の減少を加味した放電容量が得られる。
【００５２】
引き続いて、本体装置制御回路６は、自己放電補正回路２２から得られた電流積算データから、電池ブロック３における放電容量の状態を判定する。電流積算データは、充放電の繰り返しに伴う電池ブロック３における充電及び放電電流の需給状態、さらに自己放電に伴う放電容量の減少のみを反映したデータであり、電池の劣化状況を考慮していない。
【００５３】
本体装置制御回路６は、リフレッシュ充放電を行う段階における劣化状況を反映した二次電池の放電容量と、この段階での二次電池に残存する残存容量とから、リフレッシュ充放電における放電量と、充電量をそれぞれ演算する。
【００５４】
演算された結果を用いて、スイッチ６１及びスイッチ６２に切り換えることで、電池ブロック３とリフレッシュ放電負荷２８とを接続して放電を行う。この時、放電される電気量は、電流検出抵抗８により検出されており、制御部７によって放電量の検出がなされる。さらに、放電が終了すると制御装置６は、スイッチ６２を切り換え電池ブロック３の充電を開始する。この時も前記と同様に電池ブロック３に供給される電流は、電流検出抵抗８により検出されており、記憶回路２９に記憶された放電容量に相当する電流量の充電がなされると、一連のリフレッシュ充放電が終了する。
【００５５】
（実施例２）
図２は、本発明の第２の実施例における充放電のリフレッシュ充放電機能を有する電池パック及び本体装置の構成を示すブロック図である。本実施例における電池パック１は、電池ブロック３の残存容量に基づいて本体装置２による充電制御する構成を有している。
【００５６】
尚、この実施例２では、前記の実施例１と同一の構成、機能を有する部位に関する説明を省略し、構成、機能上の相違点から本実施例における特徴を明らかにする。
【００５７】
図２において、容量比較回路２５は、電池ブロック３における放電容量と予め設定された容量との比較を行うものであり、この容量は放電容量設定回路２４に記憶されている。また、比較回路２５には記憶回路３１も接続されており、この回路３１において放電深度の浅い充放電を繰り返した場合における電池の劣化状態を示す放電容量の変化が記憶される。
【００５８】
まず、図２における通常時の充電制御について説明する。自己放電補正回路２２は、充放電経路の印加される充電電流及び放電電流、及び電池の自己放電量から算出された電池ブロック３の放電容量を出力する。容量比較回路２５は、出力された放電容量と、容量設定回路２４に設定された値との比較を行う。本体負荷５への電力供給によって電池ブロック３の残存容量が設定値を下回れば、充電が必要と判断する。この時、容量比較回路２４が充電要求信号を装置本体制御回路７へ出力することで、充電電源から電力供給がなされる。このように本実施例における電池パック１は、充電要求信号を出力し、間欠充電等の開始を制御する。本体装置２は、電池パック側による制御に応じてスイッチを切り替え、充電電源９から電力供給を行うことで、電池パック１の充電を行う。
【００５９】
電池ブロック３への充放電が頻繁になされる使用用途においては、自己放電による影響は少ない。しかしながら、電池パック３の使用が長期間に亘ってなされない場合、前記の充電要求信号は、電池ブロック３での自己放電に起因する残存容量の低下相当分を補充電するために、充電要求信号を前記制御回路７に出力される。この補充電が複数回に行われた場合には、電池ブロック３を構成する二次電池は、巨視的に見ると浅い充放電が複数回繰り返されていることになる。しかしながら、電池ブロック３における残存容量の低下は、自己放電に伴う放電容量の減少、及び本体負荷等における微小な電流消費によるものであり、電流検出抵抗８にて検出されない。一方、補充電を行う際には、電流検出抵抗８において電池ブロック３への充電電流が検出される。このような一連の補充電を実施する過程において、充放電検出回路１１は充電電流のみを検出しており、充電電流と放電電流の切り替えがなされないために、充放電回数の計数値は増加しない。
【００６０】
容量比較回路１１は、充電要求信号を本体装置２へ出力した回数の累積を記憶している。さらに、この回路１１が累積値が所定の値に達した際に、リフレッシュ充放電を実施する信号を出力し、リフレッシュ充放電を行うことで、自己放電に伴う浅い放電に起因するメモリー効果の発生が抑制される。また、このリフレッシュ放電時における放電条件は、記憶回路３１に記憶された補充電を行った回数と電池の劣化程度の関係から設定されており、この放電条件に従ってリフレッシュ充放電がなされる。
【００６１】
上記各実施例においては、電池パック１が装着される本体装置内に、充電機能、リフレッシュ充放電機能を有する場合について説明したが、本体装置と充電器が別個独立の構成としても良く、また電池パック及び本体装置が同一筐体内に収容される構成にあっても、本実施例と同様の効果が得られるものである。
【００６２】
【発明の効果】
以上のように本発明の電池パックは、充放電の繰り返し回数に基づいてリフレッシュ充放電要求信号を出力する機能を加えて、リフレッシュ充放電を実施する条件を二次電池の劣化状態及び残存容量から設定する。このため、リフレッシュ充放電時の容量に対する演算精度の向上を図ることが可能となり、二次電池の劣化防止への効果は大きい。
【図面の簡単な説明】
【図１】実施例１における電池パック及び本体装置の構成を示すブロック図
【図２】実施例２における電池パック及び本体装置の構成を示すブロック図
【図３】従来例における電池パックの構成を示すブロック図
【図４】充放電の繰り返し回数と放電容量との関係を示す図
【符号の説明】
１電池パック
２本体装置
３電池ブロック
５本体負荷
６装置本体制御回路
７制御部
８電流検出抵抗
９充電電源
１１充放電検出回路
１２回数計測回路
１３温度センサー
１４温度補正テーブル回路
１５数値補正回路
１６充放電繰り返し回数カウンタ
１７通信回路
１８リフレッシュ充放電要求手段
１９数値設定回路
２０数値比較回路
２１電流積算回路
２２自己放電補正回路
２３自己放電量演算回路
２４容量設定回路
２５容量比較回路
２６電圧検出回路
２９記憶回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary battery, in particular, a secondary battery using nickel for a positive electrode such as a nickel-metal hydride battery, and a discharge capacity and a change in current applied to a charge / discharge path connected to the secondary battery. The present invention relates to a state management method for a secondary battery that controls refresh charge / discharge based on the number of charge / discharge repetitions, and a battery pack using the same.
[0002]
[Prior art]
In recent years, a battery pack containing a chargeable / dischargeable battery has been used as a power source for a portable device such as a notebook computer or a camcorder, or a vehicle equipped with a power assist mechanism that uses power from a motor as an assist. The battery pack is provided with control means for controlling the charge / discharge state of the battery and protecting the battery in the event of an abnormality.
[0003]
In the case where a secondary battery using nickel as a positive electrode such as a nickel-cadmium battery or a nickel-hydrogen battery (hereinafter referred to as a secondary battery) is used as the battery, charge / discharge having a shallow depth of discharge is repeated. When this occurs, a phenomenon in which the discharge capacity decreases, a so-called memory effect occurs. In order to suppress the occurrence of the memory effect, a method of performing a discharge with a deep discharge depth after a predetermined number of charge / discharge cycles has been used in a device using the secondary battery. In such a device, there is known a configuration in which the control means counts the number of times of charge / discharge, and when the number of times reaches a predetermined value, refresh charge / discharge is performed (for example, Japanese Patent Laid-Open Publication No. No. 6-105475).
[0004]
The charge / discharge count is calculated as follows: one cycle of charging / discharging is performed after the battery has been discharged from a charged secondary battery until the capacity falls below a predetermined capacity value and then charged until the battery reaches a fully charged state. Assuming that the count is completed, one count is added to the count value from the start of use stored in the battery pack. FIG. 3 shows an example of a circuit of a device having such a counting function.
[0005]
In FIG. 3, the battery pack 1 has a battery block 3 to which a plurality of secondary battery cells are connected, and a control unit 7 for measuring the number of times of charging and discharging. When the battery pack 1 is mounted on the main body device 2, the amount of charging electricity supplied to the secondary battery 3 and the amount of discharging electricity supplied from the battery block 3 to the main body device 2 are detected by the current detection resistor 8. . The control unit 7 calculates by converting a potential difference generated at both ends of the current detection resistor 8 by a charging / discharging current applied to a charging / discharging path to which the battery block 3 is connected. Further, by determining whether the potential difference is positive or negative, the charge / discharge detection circuit 11 detects whether the current applied to the battery block 3 is a charging current or a discharging current. For example, if the secondary battery 3 is in a discharging state, the discharge current is measured, and the discharge current value is calculated by integrating the discharge current value in the discharge current integrating circuit 30. The obtained discharge electricity amount is compared by a discharge capacity comparison circuit 32 with a discharge capacity value preset in the discharge capacity setting circuit 31. When the amount of discharged electricity exceeds the set discharge capacity and the secondary battery 3 is switched from the discharged state to the charged state, the count value stored in the charge / discharge number counter 14 is increased by one and the discharge current is increased. The value of the amount of discharged electricity accumulated in the accumulation circuit 30 is reset. When the charging state continues and the secondary battery 3 starts to be discharged again after being fully charged, the above process is repeated to count the number of times of charging and discharging.
[0006]
The refresh charging / discharging is controlled by the apparatus main body control unit 6 in response to the number of charging / discharging transmitted from the communication circuit 17. When performing this charge / discharge, the control unit 6 switches the switches 61 and 62 to the refresh discharge load 28 arranged in parallel with the main body load 5 to discharge the discharge capacity remaining in the battery block 3. The discharge capacity is determined based on the discharge capacity in the initial state of the battery and the discharge capacity obtained from a change in the discharge voltage when deep discharge is performed. When the discharging is completed, the switch is switched again to charge the battery block 3.
[0007]
[Problems to be solved by the invention]
Recently, as a trend of charge / discharge control for secondary batteries, a backup power supply of an uninterruptible power supply has a control method of intermittently charging only the self-discharged part of the battery, and a constant use of an AC adapter such as a notebook PC. In such a configuration, the control method of compensating for the decrease in the capacity of the battery by temporary charging is mainly used, and charging is performed before complete discharging. In addition, when the battery is used to assist the power of a vehicle, shallow charge / discharge control is more preferable in order to extend the life of the battery and to suppress acceleration of deterioration due to heat generation of the battery. Against this background, the generation of the memory effect is promoted by a charge control method in which charge and discharge are performed repeatedly at a shallow depth of discharge. Despite having such a background, the number of times that refresh charging is performed is reduced in order to cope with the usage state of the device.
[0008]
On the other hand, the discharge capacity of the secondary battery gradually decreases due to the deterioration of the battery. The degree of deterioration is greatly affected not only by the number of times of charge / discharge but also by the temperature condition of the environment in which the battery is used. For example, as shown in FIG. 4, the life of a battery used in a high temperature environment of 40 ° C. is shorter than that of a secondary battery used in a temperature environment of 20 ° C. Therefore, the deterioration of the secondary battery used in a high-temperature environment is accelerated. In particular, such secondary batteries are mainly used as a backup power supply for an uninterruptible power supply, a notebook PC power supply, and a power supply for a vehicle. The temperature of the environment in which it is used is greatly affected by an excessive temperature change due to use.
[0009]
The depth of discharge in refresh charge / discharge is set from the discharge capacity of the battery. The discharge capacity of the secondary battery is decreasing due to the progress of deterioration, and a deeper discharge is performed to correct the initial capacity, thereby ensuring the accuracy of the discharge capacity. However, in a device in which the charge / discharge control is set as described above, only a discharge having a shallow depth is repeated, which is a use condition in which a memory effect easily occurs. Therefore, it is very difficult to periodically perform refresh charging on these devices and correct the discharge capacity in consideration of usage. Therefore, if the discharge capacity is not corrected and the depth of discharge during refresh charge / discharge is set based on the discharge capacity in the initial state, a capacity exceeding the dischargeable capacity of the secondary battery is discharged, and There is a problem that it may fall into.
[0010]
With respect to the above problems, a configuration is conceivable in which the degree of deterioration of the secondary battery is estimated from the number of repetitions of charge and discharge, and the initial capacity is corrected to suppress occurrence of overdischarge during refresh charge. Can be In the above devices, the temperature of the environment in which the devices are used changes drastically, and the deterioration of the devices is accelerated in a high-temperature environment. Therefore, it is very difficult to accurately estimate the discharge capacity. For this reason, even when the discharge capacity is calculated only from the number of repetitions of charge / discharge and the refresh discharge is performed, the same problem as described above occurs.
[0011]
The present invention has been made in view of the above-described problems, and a state management device for a secondary battery that allows a depth of discharge when performing refresh charge / discharge of a secondary battery to be accurately set according to a degree of battery deterioration. And a battery pack using the same.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a method for managing the state of a secondary battery of the present invention and a battery pack using this method provide a secondary battery capable of charging / discharging until the battery reaches a predetermined discharge capacity or less. Charging until reaching a charged state or a predetermined capacity is defined as one cycle, and a value obtained by multiplying by a coefficient set according to a change state of the battery temperature during this one cycle is added to the number of repetitions of charging and discharging. The charge / discharge repetition count is accumulated, and the timing of the refresh charge / discharge and the discharge capacity of the secondary battery corresponding to the accumulated value are estimated from the accumulated value. The remaining capacity is calculated from the above, and the conditions for refresh charge / discharge are set together.
[0013]
According to the configuration of the present invention, the count value of the number of times of charging and discharging increases in accordance with the ambient temperature of the battery, and is used in an environment deviating from a normal temperature condition, that is, used in a high or low temperature environment, and deteriorates. Even if the secondary battery accelerates its progress, the condition of refresh charge / discharge is set in consideration of the deterioration state, so the secondary battery may fall into an inappropriate state such as overcharge or overdischarge There is no.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0015]
The invention according to claim 1 of the present application measures a charging current to a chargeable / dischargeable secondary battery and a discharge current from the secondary battery, counts the number of times of charging / discharging the secondary battery, and accumulates the number of times. The present invention relates to a method for managing the state of a secondary battery that performs refresh charge / discharge when the value reaches a predetermined value.
[0016]
This state management method of the secondary battery determines the charge current and the discharge current from the direction of the current applied to the charge / discharge path, and at the same time, measures the amount of each current of the charge / discharge. When both the charging current and the discharging current are applied, preferably after the secondary battery is discharged until the remaining capacity reaches the first capacity or less, and when the secondary battery is charged until the remaining capacity reaches the second capacity. Assuming that one cycle of charging and discharging has been performed, the remaining capacity of the secondary battery after this cycle is detected.
[0017]
At the same time, the state management method measures the ambient temperature of the secondary battery, averages the ambient temperature during a charge / discharge cycle, selects a preset correction coefficient of the number of charge / discharge corresponding to this temperature, The number of temperature-corrected cycles multiplied by the correction coefficient is added to the cumulative value of the number of charge / discharge times to obtain the new number of charge / discharge times, and the number of charge / discharge times reflecting the ambient temperature condition of the secondary battery is calculated. Calculate the cumulative value.
[0018]
Further, in the state management method described above, the refresh charge / discharge is performed when the cumulative value of the number of charge / discharge reaches a predetermined set value. Each condition of charge and discharge in this charge and discharge is referred to from the relational expression indicating the discharge capacity corresponding to the number of times of charge and discharge of the secondary battery with reference to the cumulative value of the number of times of charge and discharge reflecting the temperature condition. The discharge capacity of the secondary battery at the accumulated value is calculated, and conditions for the amount of discharge and the amount of charge in the refresh charge / discharge are set. That is, the discharge amount at the time of refresh charge / discharge is set from the discharge capacity obtained from the number of times of charge / discharge of the battery and the remaining capacity, and the charge amount at the time of refresh charge / discharge is set from the discharge amount and the discharge capacity.
[0019]
As described above, according to the state management method of the secondary battery of the present invention, the discharge capacity of the battery reflecting the deterioration state of the battery at the time of refresh charge / discharge is estimated, and supplied to the secondary battery with reference to this. By calculating the remaining capacity by calculating the integrated value of the charge current amount and the discharge current, the discharge and charge conditions in refresh charge and discharge are set, so that the refresh charge and discharge do not adversely affect the secondary battery Can be implemented. In particular, at the time of discharging, since the amount of discharge is calculated from the remaining capacity of the secondary battery and the discharge capacity of the battery reflecting the deteriorated state, the secondary battery does not fall into an overcharged state. In addition, even during charging, an overcharge state does not occur because the charging condition is set based on the discharging condition.
[0020]
Further, in the step of performing the time of refresh charge / discharge, in addition to managing the charge / discharge state of the secondary battery according to the above conditions, the charge / discharge state of the secondary battery is managed by the discharge voltage value and the charge voltage value. This greatly improves the accuracy of the charge / discharge control as compared with a known refresh charge / discharge method in which control is performed only from the charge / discharge voltage of the secondary battery.
[0021]
In addition to the secondary battery state management method according to claim 1, the self-discharge amount in one cycle is calculated from the relational expression between the ambient temperature of the secondary battery and the corresponding self-discharge amount. Calculate the amount of self-discharge of the secondary battery, find the remaining capacity by subtracting this amount of self-discharge from the remaining capacity obtained by integrating the charge / discharge current, and use this remaining capacity to set the discharge and charge conditions during refresh charge / discharge. May be performed. According to this condition setting, even when the battery is used in a temperature environment where the amount of self-discharge is large, or even when the charge-discharge cycle is for a long period and the capacity decrease due to the self-discharge is remarkable, the secondary Accurate refresh charging / discharging conditions can be set in consideration of the difference in the amount of self-discharge due to fluctuations in the environmental temperature in which the battery is placed.
[0022]
On the other hand, the invention according to claim 3 of the present application is configured such that a chargeable / dischargeable secondary battery is connected to a refresh charge / discharge unit connected via a charge / discharge path and a charging power supply, and a predetermined number of times of charge / discharge is performed. The present invention relates to a battery pack that performs refresh charge / discharge when repeated.
[0023]
This battery pack detects the number of times of charging and discharging from the secondary battery and the direction of the current applied to the charging / discharging path, and discharges the remaining capacity of the secondary battery from the applied charging current amount and the discharging current amount. Control means for detecting the temperature of the secondary battery, temperature detection means for detecting the ambient temperature of the secondary battery, and discharge capacity corresponding to the number of times of charging and discharging of the secondary battery are stored. And a refresh charge / discharge requesting means for requesting the refresh discharge means to perform refresh charge / discharge when the number of charge / discharge times reaches a predetermined number.
[0024]
Here, the control means includes a charge / discharge detection circuit for measuring the amount of charge current and the amount of discharge current applied to the secondary battery from the current detection resistor interposed in the charge / discharge path; A temperature correction circuit that calculates the averaged ambient temperature of the secondary battery in the above and selects a preset correction coefficient of the number of times of charging and discharging corresponding to this temperature, and corrects the accumulated value of the number of times of charging and discharging up to the previous time. A charge / discharge repetition number measurement circuit that calculates a cumulative value of a new number of charge / discharge times by adding an increment value multiplied by a coefficient, and calculates the remaining capacity of the secondary battery from the charge current amount during one cycle and the discharge current amount. It is composed of a current integrating circuit for calculating.
[0025]
Further, in the battery pack, when the number of times of charge / discharge reaches the value set in the refresh charge / discharge requesting means, the storage means stores the relational expression indicating the relationship between the number of times of temperature-corrected charge / discharge and the discharge capacity. With reference to the figure, the discharge capacity of the secondary battery corresponding to the number of times of charge / discharge is calculated.
[0026]
The battery pack according to the present invention transmits the number of times of charge / discharge, the remaining capacity, and the discharge capacity detected and calculated by the respective means to the refresh charge / discharge means, and sets the discharge amount during refresh discharge from the discharge capacity and the remaining capacity. And the charge amount is set from the discharge amount and the discharge capacity.
[0027]
According to the configuration of the third aspect, the deterioration state of the battery reflecting the influence of the environmental temperature in which the battery is placed is estimated by measuring the number of times of charging and discharging of the battery and the ambient temperature of the battery. Then, the charging / discharging condition of the refresh charging / discharging is set in consideration of the above-mentioned deterioration state and further with reference to the remaining capacity of the secondary battery calculated from the charging / discharging current to the secondary battery. Therefore, compared to a known refresh charge / discharge circuit that controls the refresh charge / discharge of the battery only from the battery voltage, the battery does not fall into the overdischarge state during the refresh discharge and the overcharge state during the charge, and the life of the secondary battery is reduced. Does not adversely affect
[0028]
Further, in comparison with the refresh charge / discharge circuit having a known configuration shown in FIG. 3, which controls the execution timing of the refresh charge / discharge only from the number of times of charge / discharge, the refresh charge / discharge circuit according to the present invention takes account of the environmental temperature of the battery. are doing. For example, when the temperature is high, the probability of occurrence of the memory effect is assumed to be high, and the cumulative value is increased by at least two cycles for one cycle of charge / discharge, and the cumulative value is larger than the actual number of charge / discharge repetitions. Get higher. Therefore, in a secondary battery used in a high-temperature environment, refresh charging / discharging is performed earlier at a time when refresh charging / discharging is performed than in a battery used in a normal temperature environment.
[0029]
On the other hand, the circuit of the battery pack of the present invention is provided with temperature detecting means for measuring the battery ambient temperature, and is configured to reflect the increase in the number of times per cycle in accordance with the ambient temperature. It merely adds a storage means for storing the relationship with the known circuit, and does not complicate the configuration as compared with the known refresh charge / discharge circuit that performs refresh charge / discharge only from the known number of charge / discharge repetitions.
[0030]
Still further, the invention according to claim 5 of the present application is directed to a refresh charge / discharge means connected to a chargeable / dischargeable secondary battery via a charge / discharge path, and a charge power supply, and a remaining capacity of the secondary battery. The present invention also relates to a battery pack that determines the execution time of refresh charge / discharge from the number of times of charging.
[0031]
This battery pack detects the number of times of charging / discharging from the direction of the current applied to the secondary battery and the charging / discharging path, as well as the amount of current for charging and discharging applied to the secondary battery and the self-discharge of the secondary battery. Control means for detecting the remaining capacity from the amount, and remaining capacity comparing means for requesting charging of the charger power supply when the remaining capacity of the secondary battery falls below a predetermined capacity value and accumulating the number of times of charging. And a temperature detecting means arranged in contact with or facing the surface of the secondary battery to detect an ambient temperature of the secondary battery, and a storage storing a relationship between the number of times of charging the secondary battery and the discharge capacity. Means, and a refresh charge / discharge requesting means for requesting refresh charge / discharge to the refresh discharge means.
[0032]
Further, the detailed configuration of the control means includes a charge / discharge detection circuit for measuring a charge current amount and a discharge current amount from the current detection resistor interposed in the charge / discharge path to the secondary battery, and a detection value of the temperature detection means. A temperature correction circuit for averaging the ambient temperature of the secondary battery and selecting a preset correction coefficient of the number of charge / discharge times corresponding to the average ambient temperature, the cumulative value of the number of charge / discharge times up to the previous time, and the correction A charge / discharge repetition number measurement circuit that calculates the number of charge / discharge operations by calculating a new cumulative value from the coefficient, a current integration circuit that integrates the charge current amount and the discharge current amount, and a self-discharge amount corresponding to the ambient temperature of the secondary battery A self-discharge operation circuit for selecting a self-discharge amount corresponding to the average ambient temperature of the secondary battery and subtracting the self-discharge amount from the remaining capacity calculated by the current integrating circuit to obtain a remaining capacity is provided. Have been.
[0033]
The battery pack according to claim 5, wherein when the number of charges reaches the value set in the refresh charge / discharge requesting means, the storage means stores the secondary battery corresponding to the temperature-corrected number of charges. Calculate the discharge capacity of the battery, and set the discharge amount at the time of refresh charge / discharge in the refresh charge / discharge means from this discharge capacity and the remaining capacity corrected for self-discharge, and set this discharge amount and the storage means The amount of charge at the time of refresh charge / discharge is set from the discharged discharge capacity.
[0034]
According to this configuration, even in a battery pack in which only the supplementary charge of the current amount corresponding to the self-discharge amount is repeated, the time and conditions for performing the refresh charge / discharge can be reduced by estimating the number of charges and the self-discharge amount. Is set. Furthermore, even in a battery pack that is used in such a manner that charging and discharging with a deep depth of discharge are repeated, the execution condition of refresh charging and discharging is set in consideration of the self-discharge amount of the battery in addition to the number of times of charging and the ambient temperature of the battery. And the occurrence of the memory effect is suppressed.
[0035]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present embodiment shows an example of the configuration of the present invention, and does not limit the scope thereof. Components that perform the same functions as those of the conventional example are denoted by the same reference numerals, and detailed description is omitted.
[0036]
(Example 1)
FIG. 1 is a block diagram showing a configuration of a battery pack and a main unit having a charge / discharge refresh charge / discharge function according to a first embodiment of the present invention. In FIG. 1, a battery pack 1 has a built-in battery block 3 in which a plurality of secondary battery cells are connected in series and a control unit 7, and is connected to a main device 2 having a load 5. The electrical connection between the battery pack 1 and the main unit is made from the terminals 41 to 46.
[0037]
Inside the battery pack 1, a current detection resistor 8 is interposed in a charge / discharge path connecting the battery block 3 with the terminals 42 and 43. The current detection resistor 8 measures the charging current supplied to the battery block 3, the discharge current supplied from the battery block 3 to the main body load 5, and the refresh discharge load 28 during refresh charge / discharge, and the value of each current is detected. It is expressed as a potential difference between both ends of the resistor 6. The control unit 7 is configured by various circuits including AD conversion circuits 101 to 103 for converting a value measured by an analog value into a digital value.
[0038]
The main body device 2 is connected to the charge / discharge path on the battery pack 1 side via the terminals 44 and 45, and supplies and supplies each current of charge / discharge. Further, a switch 61 and a switch 62 are interposed in the charge / discharge path on the main body device 2 side, and by switching these switches, power is supplied from the battery block 3 to the main body load 5 and charging by the charging power supply 9 is performed. And a refresh discharge by the refresh discharge load 28 is performed. The voltage applied to the charging path is detected by the voltage detection circuit 26. The device main body control circuit 6 switches the switches 61 and 62 based on various data sent from the battery pack 1 in addition to the above-described voltage value, to charge the battery block 3, supply power to the main body load 5, Controls the execution of refresh charge / discharge.
[0039]
Next, a detailed configuration of the battery pack 1 including the control circuit 7 will be described. The charge / discharge detection circuit 11 determines charging and discharging from the potential difference generated between both ends of the current detection resistor, and measures each current value of charging / discharging applied to the battery block 3. It is output to the measurement circuit 12 and the number of times of charging and discharging is counted. The temperature sensor 13 is arranged adjacent to the battery block 3 and measures an ambient temperature of the battery block 3. The measured battery temperature is output to the temperature correction table circuit 14. The temperature correction table circuit 14 stores a temperature change during the charge / discharge period of the battery and corrects the degree of deterioration of the battery due to the temperature based on the stored temperature change. The numerical value correction circuit 15 corrects the number of times of charge / discharge based on the output results of the temperature correction table circuit 14 and the number-of-times measurement circuit 12, and is stored in the charge / discharge repetition number counter 16. The stored number of charge / discharge repetitions is transmitted to the main unit 2 via the communication circuit 17 and output to the refresh charge / discharge request means 18 including the numerical value setting circuit 19 and the numerical value comparison circuit 20.
[0040]
The numerical value setting circuit 19 sets the number of repetitions of the charge / discharge for performing the refresh charge / discharge, and the setting of the number is set according to the use mode of the main unit 2 to which the battery pack 1 is connected. When the number of times of charging / discharging of the battery block 3 reaches the set value, the numerical comparing circuit 20 outputs a signal requesting refresh charging / discharging.
[0041]
Each current value of charge / discharge output from the charge / discharge detection circuit 11 is integrated in the current integration circuit 21. Further, the temperature in the battery block 3 measured by the temperature sensor 13 is output to the self-discharge amount calculation circuit 22, and the circuit 11 calculates the self-discharge amount based on the temperature condition. The self-discharge correction circuit 22 calculates the remaining capacity in the battery block 3 in consideration of the amount of self-discharge due to a change in temperature in addition to the change in discharge capacity due to repeated charging and discharging.
[0042]
The storage device 29 stores the battery characteristics of the secondary batteries constituting the battery block 3, and at least the transition of the discharge capacity accompanying the repetition of charge and discharge under a normal temperature environment. The transition of the discharge capacity stores, for example, the number of repetitions of charge / discharge and the discharge capacity as shown in FIG. This makes it possible to estimate the discharge capacity of the battery under a normal temperature environment from the number of times of charge / discharge with respect to the change in the discharge capacity due to the deterioration of the battery due to repeated charge / discharge.
[0043]
Next, the operation of the circuit in this embodiment will be described.
[0044]
The potential difference generated at both ends of the current detection resistor 6 is converted into digital data by the AD conversion circuit 101, and the charge / discharge detection circuit 11 detects whether the digital data is in a discharged state or a charged state. The number-of-times measuring circuit 12 measures the number of times of one time when switching from discharging to charging.
[0045]
The temperature data detected by the temperature sensor 13 is averaged in a temperature correction table circuit 14 and converted into a correction value. This conversion of the correction value is performed to correct the number of repetitions of charging and discharging depending on the battery temperature. For example, when the average temperature is high, the deterioration of the battery is accelerated, and when one charge / discharge is performed, a correction value for increasing the number of times of charge / discharge in consideration of the accelerated deterioration due to the temperature is output. On the basis of the correction value output from the temperature correction table circuit 14 and the count value in the number-of-times measurement circuit 12, the numerical value correction circuit 15 calculates the number of repetitions of charging and discharging. At this time, the increment value of the number output by the number measurement circuit 12 is calculated by adding and multiplying the correction value. Further, the increase value of the number of times the temperature has been corrected is input to the charge / discharge repetition number counter 16, and the count is performed in accordance with the increase value of the number of times, where the number of charge / discharge repetitions is stored. Thus, for example, even for a battery placed in a high-temperature environment, the number of charge / discharge repetitions reflecting the acceleration of deterioration due to temperature is calculated, and it is possible to determine the degree of deterioration of the battery only from this number of repetitions. Become.
[0046]
The number of charge / discharge repetitions stored in the counter 16 is input to the refresh charge / discharge request unit 18. The number of times of charging / discharging output from the counter 16 is input to the numerical value comparing circuit 20 and compared with the numerical value set in the numerical value setting circuit. As described above, the numerical value setting circuit 19 stores the cumulative number of charging / discharging to be performed for the refresh charging / discharging, and the numerical comparing circuit 20 determines that the number of repetitions of the temperature-corrected charging / discharging reaches the preset cumulative number. Then, a refresh charge / discharge request signal is output.
[0047]
The charge / discharge detection circuit 11 also measures the amounts of charge and discharge currents applied to the charge / discharge path in addition to the detection of charge / discharge switching. The charge / discharge current data output from the charge / discharge current detection circuit 11 is input to a current integration circuit 21, where an integration operation is performed to calculate the remaining capacity of the battery block 3. This calculation is performed by subtracting the amount of current accompanying the discharge from the discharge capacity at the time of discharging from the discharge capacity in the initial state set in the current integrating circuit 21 and changing from discharging to charging. The amount of current supplied to the block 3 is added to the above-mentioned subtracted discharge capacity.
[0048]
Further, the discharge capacity calculated in the above process reflects a considerable amount of the capacity decrease due to self-discharge with respect to the discharge capacity. Since the self-discharge varies depending on the environmental temperature at which the battery pack 1 is placed, the self-discharge amount calculation circuit 23 captures the temperature detected by the temperature sensor 13 and calculates the self-discharge amount based on the obtained temperature data. Is calculated. In this embodiment, the self-discharge amount is calculated from the battery temperature. However, in addition to the battery temperature, the self-discharge amount is also considered in consideration of the idle period during which the supply / discharge current of the battery block 3 is not supplied. By calculating the self-discharge amount, the detection accuracy of the discharge capacity of the battery block 3 is further improved. The self-discharge correction circuit 22 subtracts and corrects the self-discharge amount from the current integrated data, and outputs the self-discharge subtracted corrected current integrated data.
[0049]
The number of charge / discharge repetitions output from the charge / discharge repetition counter 16, the request signal output from the refresh charge / discharge requesting means, the discharge capacity of the battery block 3 output from the self-discharge correction circuit, and further set in the storage circuit Each data relating to the state of the discharge capacity due to the deterioration of the battery is serially converted by the communication circuit 17 and transmitted to the main unit 2.
[0050]
The main unit 2 performs the refresh charge / discharge according to the refresh charge / discharge request signal sent from the battery pack 1. The main unit control circuit 6 sets the charging and discharging conditions for the refresh charging and discharging based on the data received from the communication circuit 17, and performs the charging and discharging. The main body control circuit 6 starts a series of refresh charge / discharge operations in response to a request signal from refresh charge / discharge requesting means.
[0051]
Next, the state of deterioration of each of the secondary batteries constituting the battery block 3 is estimated from the number of charge / discharge repetitions and the number of charge / discharges stored in the storage means, and the discharge capacity of the battery corresponding to the degree of the deterioration is estimated. Get data. As described above, the number of charge / discharge repetitions is a value reflecting the accelerated state of battery deterioration due to environmental temperature, and by obtaining a discharge capacity corresponding to the number of charge / discharge repetitions set in the storage circuit, It is possible to obtain a discharge capacity that takes into account a decrease in the discharge capacity due to deterioration.
[0052]
Subsequently, the main unit control circuit 6 determines the state of the discharge capacity in the battery block 3 from the current integrated data obtained from the self-discharge correction circuit 22. The current integration data reflects only the supply and demand state of the charge and discharge currents in the battery block 3 due to the repetition of charge and discharge, and further reflects the reduction in the discharge capacity due to self-discharge, and does not take into account the state of deterioration of the battery.
[0053]
The main unit control circuit 6 calculates the amount of discharge in the refresh charge / discharge from the discharge capacity of the secondary battery reflecting the deterioration state at the stage of performing the refresh charge / discharge and the remaining capacity remaining in the secondary battery at this stage. The charge amount is calculated respectively.
[0054]
The battery block 3 and the refresh discharge load 28 are connected and discharged by switching to the switch 61 and the switch 62 using the calculated result. At this time, the amount of electricity discharged is detected by the current detection resistor 8, and the control unit 7 detects the amount of discharge. Further, when the discharging is completed, the control device 6 switches the switch 62 to start charging the battery block 3. At this time as well, the current supplied to the battery block 3 is detected by the current detection resistor 8 in the same manner as described above, and when the current amount corresponding to the discharge capacity stored in the storage circuit 29 is charged, a series of operations is performed. The refresh charge / discharge ends.
[0055]
(Example 2)
FIG. 2 is a block diagram showing the configuration of a battery pack having a charge / discharge refresh charge / discharge function and a main unit according to a second embodiment of the present invention. The battery pack 1 according to the present embodiment has a configuration in which charging is controlled by the main device 2 based on the remaining capacity of the battery block 3.
[0056]
In the second embodiment, the description of the parts having the same configuration and function as those of the first embodiment is omitted, and the features of the second embodiment will be clarified from the difference in the configuration and function.
[0057]
In FIG. 2, a capacity comparison circuit 25 compares the discharge capacity in the battery block 3 with a preset capacity, and this capacity is stored in the discharge capacity setting circuit 24. Further, a storage circuit 31 is also connected to the comparison circuit 25. In this circuit 31, a change in the discharge capacity indicating the state of deterioration of the battery when charging / discharging having a small depth of discharge is repeated is stored.
[0058]
First, the normal charge control in FIG. 2 will be described. The self-discharge correction circuit 22 outputs a charge capacity and a discharge current applied to the charge / discharge path and a discharge capacity of the battery block 3 calculated from a self-discharge amount of the battery. The capacity comparison circuit 25 compares the output discharge capacity with the value set in the capacity setting circuit 24. If the remaining capacity of the battery block 3 falls below the set value due to power supply to the main body load 5, it is determined that charging is necessary. At this time, the capacity comparison circuit 24 outputs a charge request signal to the apparatus main body control circuit 7, whereby power is supplied from the charge power supply. As described above, the battery pack 1 in the present embodiment outputs the charge request signal and controls the start of the intermittent charge and the like. The main body device 2 switches the switch according to the control by the battery pack side and supplies power from the charging power supply 9 to charge the battery pack 1.
[0059]
In use applications where the battery block 3 is frequently charged and discharged, the influence of self-discharge is small. However, when the use of the battery pack 3 is not performed for a long period of time, the charge request signal is a charge request signal for supplementing the amount corresponding to the decrease in the remaining capacity due to the self-discharge in the battery block 3. Is output to the control circuit 7. When the supplementary charging is performed a plurality of times, the secondary battery constituting the battery block 3 is macroscopically subjected to shallow charging / discharging a plurality of times. However, the decrease in the remaining capacity in the battery block 3 is due to the decrease in the discharge capacity due to the self-discharge and the minute current consumption in the main body load and the like, and is not detected by the current detection resistor 8. On the other hand, when performing supplementary charging, the current detection resistor 8 detects the charging current to the battery block 3. In the process of performing such a series of supplementary charging, the charging / discharging detection circuit 11 detects only the charging current, and the switching between the charging current and the discharging current is not performed, so the count value of the number of charging / discharging does not increase. .
[0060]
The capacity comparison circuit 11 stores the accumulation of the number of times that the charge request signal has been output to the main device 2. Further, when the accumulated value reaches a predetermined value, the circuit 11 outputs a signal for performing a refresh charge / discharge and performs the refresh charge / discharge, thereby generating a memory effect caused by a shallow discharge accompanying the self-discharge. Is suppressed. The discharge condition at the time of the refresh discharge is set based on the relationship between the number of times of the supplementary charge stored in the storage circuit 31 and the degree of deterioration of the battery, and the refresh charge / discharge is performed according to the discharge condition.
[0061]
In each of the above embodiments, the case where the main body device to which the battery pack 1 is mounted has the charging function and the refresh charge / discharge function has been described. However, the main body device and the charger may be configured separately and independently. Even when the pack and the main unit are housed in the same housing, the same effects as in the present embodiment can be obtained.
[0062]
【The invention's effect】
As described above, the battery pack of the present invention has a function of outputting a refresh charge / discharge request signal based on the number of repetitions of charge / discharge, and the condition for performing the refresh charge / discharge is determined from the deterioration state and the remaining capacity of the secondary battery. Set. For this reason, it is possible to improve the calculation accuracy for the capacity at the time of refresh charge / discharge, and the effect of preventing the deterioration of the secondary battery is great.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a battery pack and a main body device according to a first embodiment.
FIG. 2 is a block diagram illustrating a configuration of a battery pack and a main body device according to a second embodiment.
FIG. 3 is a block diagram showing a configuration of a conventional battery pack.
FIG. 4 is a diagram showing the relationship between the number of charge / discharge repetitions and the discharge capacity.
[Explanation of symbols]
1 Battery pack
2 Main unit
3 Battery block
5 Body load
6. Device control circuit
7 control section
8 Current detection resistor
9 Charging power supply
11 Charge / discharge detection circuit
12. Counting circuit
13 Temperature sensor
14. Temperature compensation table circuit
15 Numerical correction circuit
16 charge / discharge repetition counter
17 Communication circuit
18 Refresh charge / discharge request means
19 Numerical value setting circuit
20 Numerical comparison circuit
21 Current integration circuit
22 Self-discharge correction circuit
23 Self-discharge amount calculation circuit
24 Capacity setting circuit
25 Capacity comparison circuit
26 Voltage detection circuit
29 Memory circuit

Claims

The charge current to the chargeable / dischargeable secondary battery and the discharge current from the secondary battery are measured, the number of charge / discharge of the secondary battery is counted, and when the accumulated number of times reaches a predetermined value, the refresh charge is performed. A state management method for a secondary battery that performs discharging,
The charge current and the discharge current applied to the charge / discharge path are determined, and the respective charge / discharge current amounts of the secondary battery are measured. When the charge current and the discharge current are applied to the secondary battery, one cycle is performed. Assuming that charging / discharging has been performed, detection of a dischargeable remaining capacity remaining in the secondary battery after completion of this cycle is performed,
Measure the ambient temperature of the secondary battery, calculate the averaged ambient temperature of the secondary battery during one cycle, select a preset correction coefficient of the number of times of charge and discharge corresponding to this temperature, The number of temperature-corrected cycles multiplied by this correction coefficient is added to the cumulative value of the number of times of charging and discharging to obtain the cumulative number of times of the new number of charging and discharging,
When the number of times of charge / discharge reaches a predetermined value and refresh charge / discharge is performed, the discharge capacity of the secondary battery at a predetermined value is calculated from a relational expression indicating the discharge capacity corresponding to the number of times of charge / discharge of the secondary battery,
It is assumed that the discharge capacity and the remaining capacity calculated from the charge current amount and the discharge current amount are used to set the discharge amount at the time of refresh charge and discharge, and that the discharge amount and the discharge capacity are used to set the charge amount at the time of refresh charge and discharge. A method for managing the state of a secondary battery.

A predetermined amount of ambient temperature of the secondary battery during one cycle and a self-discharge amount during one cycle are selected from a relational expression of the self-discharge amount corresponding thereto,
A method of calculating a remaining capacity by subtracting the self-discharge amount from a remaining capacity calculated from a charge current amount and a discharge current amount during the cycle, and calculating a discharge amount and a charge amount during refresh charge / discharge using the remaining capacity. 2. The method for managing the state of a secondary battery according to claim 1.

Refresh charge / discharge means connected to a chargeable / dischargeable secondary battery via a charge / discharge path, and a battery pack connected to a charging power supply and performing refresh charge / discharge when charge / discharge is repeated a predetermined number of times And
The battery pack detects the number of times of charging and discharging from the secondary battery and the direction of the current applied to the charging / discharging path, and discharges the remaining rechargeable battery of the secondary battery from the applied charging current amount and the discharging current amount. Control means for detecting the capacity, temperature detecting means arranged in contact with or facing the surface of the secondary battery to detect the ambient temperature of the secondary battery, and corresponding to the number of times of charging and discharging of the secondary battery. A storage unit in which the discharge capacity is stored, and a refresh charging / discharging requesting unit that requests refresh charging / discharging to the refresh discharging unit when the number of charging / discharging reaches a predetermined number,
The control means includes a charge / discharge detection circuit for measuring the amount of charge current and the amount of discharge current applied to the secondary battery from a current detection resistor interposed in the charge / discharge path, and one cycle from the detected value of the temperature detection means. A temperature correction circuit that calculates an averaged ambient temperature of the secondary battery during the temperature and selects a preset correction coefficient of the number of times of charging and discharging corresponding to this temperature, a cumulative value of the number of times of charging and discharging up to the previous time, A charge / discharge repetition number measuring circuit for calculating a cumulative value of a new number of charge / discharge times by calculating an increase value of the number of charge / discharge times from the correction coefficient; It consists of a current integration circuit that calculates the remaining capacity of the battery,
When the number of times of charge / discharge reaches the value set in the refresh charge / discharge requesting means, the storage means calculates the discharge capacity of the secondary battery corresponding to the number of times of temperature-corrected charge / discharge,
In the refresh charge / discharge means, the discharge capacity and the discharge capacity at the time of refresh charge / discharge are set from the remaining capacity calculated from the charge current amount and the discharge current quantity, and the discharge capacity and the discharge capacity set in the storage means are set. A battery pack using a state management method of a secondary battery, wherein a charge amount at the time of refresh charge / discharge is set from the following.

The control means sets a relational expression of the self-discharge amount corresponding to the ambient temperature of the secondary battery, and corresponds to the averaged ambient temperature of the secondary battery when at least one cycle of charging and discharging is completed. A self-discharge operation circuit for determining the remaining capacity by subtracting the self-discharge amount from the remaining capacity calculated from the charge current amount and the discharge current amount during this cycle,
4. The battery pack according to claim 3, wherein the refresh charge / discharge means calculates a discharge amount and a charge amount during refresh charge / discharge by applying the remaining capacity calculated by the arithmetic circuit. .

Refresh charge / discharge means connected to a chargeable / dischargeable secondary battery via a charge / discharge path, and a battery pack connected to a charging power supply and performing refresh charge / discharge when charge / discharge is repeated a predetermined number of times And
This battery pack detects the number of times of charging and discharging from the secondary battery and the direction of the current applied to the charging and discharging path, and determines the number of charging and discharging currents applied and the amount of self-discharge of the secondary battery. Control means for detecting a dischargeable remaining capacity of the secondary battery, and when the remaining capacity of the secondary battery falls below a predetermined capacity value, requesting charging of the charger power supply, And a temperature detecting means arranged in contact with or facing the surface of the secondary battery to detect the ambient temperature of the secondary battery, and a charge capacity corresponding to the number of times of charging the secondary battery. A storage unit having a discharge capacity stored therein, and a refresh charge / discharge requesting unit for requesting a refresh charge / discharge to the refresh discharge unit,
The control means includes: a charge / discharge detection circuit for measuring the amount of charge current and the amount of discharge current applied to the secondary battery from a current detection resistor interposed in the charge / discharge path; A temperature correction circuit for calculating an averaged ambient temperature of the next battery and selecting a preset correction coefficient of the number of times of charge / discharge corresponding to this temperature, a cumulative value of the number of times of charge / discharge up to the previous time, and the correction coefficient A charge / discharge repetition number measurement circuit that calculates a new cumulative value by calculating the increase value of the charge / discharge frequency from the current, a current integration circuit that integrates the charge current amount and the discharge current amount, and a self-discharge corresponding to the ambient temperature of the secondary battery. The amount is set, the self-discharge amount corresponding to the averaged ambient temperature of the secondary battery is selected, and the self-discharge amount is subtracted from the remaining capacity calculated by the current integration circuit to obtain the remaining capacity. It consists of the required self-discharge arithmetic circuit Cage,
When the number of charges reaches the value set in the refresh charge / discharge requesting means, the storage means calculates the discharge capacity of the secondary battery corresponding to the number of times of temperature-corrected charging,
The refresh charge / discharge means sets a discharge amount at the time of refresh charge / discharge from the discharge capacity and the remaining capacity corrected for self-discharge, and a refresh charge / discharge based on the discharge amount and the discharge capacity set in the storage means. A battery pack using a state management method for a secondary battery, wherein a charge amount at the time of discharging is set.