JP2004039434A

JP2004039434A - Charge control method of lead-acid battery

Info

Publication number: JP2004039434A
Application number: JP2002194601A
Authority: JP
Inventors: Masaaki Shiomi; 塩見　　正昭
Original assignee: Japan Storage Battery Co Ltd
Current assignee: Japan Storage Battery Co Ltd
Priority date: 2002-07-03
Filing date: 2002-07-03
Publication date: 2004-02-05

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge control method capable of constantly executing a certain amount of charge without being influenced by dispersion or a use environment/condition of a lead-acid battery, and of restraining overcharge and thereby providing a long-life lead-acid battery by adjusting a charge condition as needed based on information obtained by detecting the state of charge (SOC) of the lead-acid battery. <P>SOLUTION: This charge control method is characterized by that a charge amount is reduced to 99-102% with respect to a conventional charge amount of 110-115% in order to minimize overcharge of the lead-acid battery; and when equalizing charge is put in at the point the SOC drops to a certain amount by detecting the drop of the SOC caused by it, the charge condition of the lead-acid battery is so adjusted that the SOC drops to a predetermined value in a certain cycle range. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、鉛蓄電池の充電制御方法に関する。
【０００２】
【従来の技術】
鉛蓄電池は自動車、据置、電動車輌、太陽光発電等の多方面に使用されている。近年、このような蓄電池は高信頼性、長寿命化の要求が強くなってきている。
【０００３】
鉛蓄電池の劣化の主要因は正極格子の腐食である。すなわち、正極格子は、開回路の状態でも電位の高い正極活物質と常時接しているため、常に腐食される環境にある。充電時には充電過電圧が加わるため、腐食はさらに加速される。格子は、集電体としての機能と活物質を保持する機能を持っているが、腐食が進めばこれらの機能が低下して蓄電池の容量を低下させることになる。
【０００４】
また、特に、正極格子に実質上Ｓｂを含まない鉛合金を用いた蓄電池では、放電量が少なく、過充電される使用状態では上記の腐食の問題以外に、正極格子の酸化が進みすぎるため、放電時にその部分が優先的に放電し、正極格子と活物質との界面に硫酸鉛の絶縁層が形成され容量が低下するといった問題が生じることがある。特に、太陽光発電のように外部の負荷を平準化するために蓄電池の放電頻度が高い場合にはその影響が大きい。
【０００５】
上記問題の対策としては、過充電を抑えることが重要であるが、放電量に対して充電量が１００％に近づくにつれて副反応である水の電気分解（Ｈ_２Ｏ＝１／２Ｏ_２＋Ｈ_２）反応が並行しておこり、充電時の電気エネルギーがこの反応に使用されるために放電量に対して１００％の充電では充電不足の状態が発生する。したがって通常、放電量に対して１１０％〜１１５％程度の過充電を実施せざるを得ず、この過充電が鉛蓄電池の劣化の要因になっていることは明らかで、この過充電を抑制する充電方法がいくつか提案されている。例えば、二段定電圧充電を実施し、一段目の充電電圧に対して、充電量が１００％に近づいた時点で二段目の充電電圧を低くし、充電電流をできるだけ小さくして過充電を避ける方式がある。この方式でもそれなりの効果はあるが、鉛蓄電池を多数個接続して使用する場合、二段目の充電電圧を低くしても、充電電圧は蓄電池全個数に対してかけるために、蓄電池間でのばらつきがあるとトータルの充電電圧が低くても、個々の蓄電池にとっては高い電圧がかかっているケースも発生し、二段目の電圧を低くして過充電を抑制する効果が十分とは言えない場合がある。また、使用環境温度によっては充電電圧を低くしても、過充電状態が避けられない場合も発生する。
【０００６】
発明者はこのような問題に対して、充電において充電電圧のみを制御するのでなく、蓄電池の充電状態（Ｓｔａｔｅ　ｏｆ　Ｃｈａｒｇｅ　以降、ＳＯＣという）を検知し、その情報により蓄電池の充電条件を随時変更すれば、上記のような問題が回避され、過充電を極力抑えることができ、鉛蓄電池の寿命改善に大きく寄与することを見出した。本発明はそれによって得た知見に基づくものである。
【０００７】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、鉛蓄電池のＳＯＣを検知して得た情報をもとに随時充電条件を調整することによって、蓄電池のばらつきや使用環境温度・条件に影響されず、絶えず一定量の充電を行い、過充電を抑制し、サイクル使用における長寿命の鉛蓄電池が得られる充電制御方法を提供するものである。
【０００８】
【課題を解決するための手段】
課題を解決するための手段は、鉛蓄電池の過充電を極力抑制するために、従来の充電量、１１０〜１１５％に対して９９〜１０２％と充電量を少なくし、そのことによるＳＯＣの低下を検知し、一定量低下した時点で均等充電を挿入するに際し、一定のサイクル範囲内に所定のＳＯＣまで低下するよう蓄電池の充電条件を調整する方式を骨子とするもので、請求項１によれば、放電時の蓄電池温度、放電電流、放電電圧とＳＯＣとの関係、もしくは放電時の蓄電池温度と放電量とＳＯＣとの関係を示す基準データを得る第１ステップと、
蓄電池を放電する第２ステップと、
前記第２ステップでの放電時の蓄電池温度と放電電流と放電電圧とサイクル数、もしくは放電時の蓄電池温度と放電量とサイクル数とを測定する第３ステップと、
第３ステップでの測定データと第１ステップで得た基準データとの比較からＳＯＣを検知する第４ステップとを備え、
前記ＳＯＣの低下量があらかじめ定められたａ％未満で、かつ、サイクル数があらかじめ定められた値ｄ未満である時は、普通充電を行い、第２ステップに戻り、
前記ＳＯＣの低下量があらかじめ定められたａ％未満で、かつ、サイクル数があらかじめ定められた値ｄであるときは、充電条件変更、サイクル数のリセット、普通充電を行った後、第２ステップへ戻り、
前記ＳＯＣの低下量があらかじめ定められたａ％以上で、かつ、サイクル数があらかじめ定められた値ｃ未満である時は、均等充電を行い、次いで放電、充電条件の変更、サイクル数のリセット、普通充電を行った後、第２ステップへ戻り、
前記ＳＯＣの低下量があらかじめ定められたａ％以上で、かつ、サイクル数があらかじめ定められたｃ以上かつｄ未満の時は、均等充電、サイクル数のリセットを行い、第２ステップに戻ることを特徴とするものである。
【０００９】
上述したように、鉛蓄電池を長寿命化するためには、いかに過充電を抑えるかが重要な要素であり、従来のように充電電圧を制御するだけではその効果が十分に得られない。そこで発明者は、放電時の蓄電池温度、電流および電圧（組電池の電圧、単電池（セル）の電圧、組電池での一定単位個数の蓄電池（ブロック）の電圧）とＳＯＣとの関係もしくは、蓄電池温度と放電電気量（Ａｈ）とＳＯＣとの関係を求め、基準データとしてあらかじめ制御システムに導入し、そのデータと蓄電池を放電した際のデータと比較することによりサイクル毎の蓄電池のＳＯＣを検知すると共に、あらかじめ設定したＳＯＣ、１００％以下の充電不足状態から所定値ａ％までの低下量、例えば設定値から１０％低下した時点で均等充電を挿入するのであるが、本発明では、ＳＯＣが低下する時期を、使用期間あるいはサイクル数であらかじめ設定し、ＳＯＣが所定量に低下するのに要する期間あるいはサイクル数がその範囲を超えた場合、異常と判断し、上記所定の使用期間あるいはサイクル数内でＳＯＣが低下するよう充電条件を調整する。すなわち、ＳＯＣが１０％低下する期間を例えば５〜２０サイクルと設定し、これより早期にＳＯＣが１０％以下に低下することは、充電不足が予想以上に進んでいることを意味し、設定されている充電Ａｈ量をふやす等の措置が行う。また、２０サイクル経過した時点でＳＯＣが１０％以下に低下しないことは、過充電状態で使用されていることが予想されるため、設定されている充電Ａｈ量を少なくする等の措置を行う。このような方式であれば、例え、機器や蓄電池にばらつきや固有の誤差を含んでいても、使用中の履歴を学習して、上記のように相対的なデータから充電条件の適正化をはかることができ、蓄電池の長寿命化に非常に有効に作用する。
【００１０】
上述したように、ＳＯＣ１００％以下の低い状態で蓄電池を使用し、このＳＯＣが例えば１０％低下した時点で、もとのＳＯＣに定期的に戻すための充電を均等充電（リフレッシュ充電あるいは回復充電等とも呼ぶ）と定義している。
【００１１】
請求項２によれば、均等充電を行った際に取得した放電データをもとに基準データを修正することを特徴とするものである。
【００１２】
蓄電池は使用経過と共に経時変化するのでいつも最初に設定した基準データと比較してＳＯＣを算出し、充電条件を調整しておれば、正しい判断ができないことがあるので均等充電毎に放電データを取り、その電圧から算出されるＳＯＣと最初の基準データから算出されるＳＯＣとに違いが生じた場合には、均等充電から得たデータをもとに基準データを変更すると共に、均等充電毎に基準データを更新していくのが好ましい。
【００１３】
請求項３によれば、均等充電したにもかかわらず、第４ステップで検知したＳＯＣの低下量があらかじめ定められた値ａ％以上であって、かつ、サイクル数があらかじめ定められた値ｃ未満であることが連続して３回発生した時は、均等充電条件および基準データを変更することを特徴とするものである。
【００１４】
均等充電したにもかかわらず、あらかじめ設定したＳＯＣの低下量、例えば１０％以上に、あらかじめ設定したサイクル数、例えば５サイクル未満で到達し、均等充電条件を変更しても、このような状態が連続して３回発生した場合には、蓄電池の性能劣化が進んでしまったことを意味するので、あらかじめ入力している基準データを修正し、例えば、残存容量は新品の時よりも１０％低下しているが、充電状態は１００％であるという情報を入力してＳＯＣの調整を行う。このような劣化状態に合せた充電を行うことにより、必要以上の過充電を防止するだけでなく、上記情報からは残存容量や劣化の程度に関するデータも得られる。
【００１５】
【発明の実施の形態】
本発明は、鉛蓄電池を電動車輌や機器に組み込んで使用した場合、該蓄電池の劣化の主要因である正極格子の腐食を抑制し、寿命性能を改善しようとするもので、その実施の形態は、鉛蓄電池の過充電を極力抑制するために、従来の充電量、１１０〜１１５％に対して９９〜１０２％と充電量を少なくし、そのことによるＳＯＣの低下を検知し、一定量低下した時点で均等充電を挿入するに際し、一定のサイクル範囲内にあらかじめ定めたＳＯＣまで低下するよう、蓄電池の充電条件を調整する方式を骨子とするもので本発明が実際に運用される場合のブロック図を図１に示す。
【００１６】
図１によれば、放電時の蓄電池温度、放電電流、放電電圧とＳＯＣとの関係、もしくは放電時の蓄電池温度と放電量とＳＯＣとの関係を示す基準データを得る第１ステップと蓄電池を放電する第２ステップ、前記第２ステップでの放電時の蓄電池温度と放電電流と放電電圧とサイクル数、もしくは放電時の蓄電池温度と放電量とサイクル数とを測定する第３ステップと、第３ステップでの測定データと第１ステップで得た基準データとの比較によりＳＯＣを検知する第４ステップとからなり、ここでは、５〜２０サイクルの間にＳＯＣの低下量が１０％以下になれば均等充電を実施する例について説明する。
【００１７】
まず、２０サイクル未満で、ＳＯＣが１０％低下しない場合には、普通充電を行い、第２ステップへ戻る。２０サイクル経過した時点でＳＯＣが１０％以下に低下しない場合は、過充電傾向にあることが予想されるので、充電条件を変更し、サイクル数のリセット、普通充電を行った後、第２ステップへ戻る。次に、５サイクル未満でＳＯＣが１０％以下に低下した場合、充電不足が予想されるので、均等充電を行い、放電を行った後、充電条件を変更し、サイクル数のリセット、普通充電を行い、第２ステップへ戻る。第４番目のケースは、５サイクル以上かつ２０サイクル未満でＳＯＣが１０％低下した場合で、これは充電条件が適切であることを意味し、均等充電を行った後、充電条件は変更せず、サイクル数のリセットを行い第２ステップへ戻る。
【００１８】
以上の措置をとることによって、蓄電池にばらつきがあったり、使用環境温度・条件が異なったりしても、いつも蓄電池に適した充電がされるので過充電が抑制され寿命改善に非常に有効である。
【００１９】
【実施例】
本発明の効果を明らかにするために実施例にもとづく試験により詳細に説明する。
［試験内容および結果］
本発明の効果を明確にするための試験を行うにあたって、下記の試験用蓄電池を製作した。
【００２０】
正・負極板にＰｂ−０．０７質量％Ｃａ−１．３質量％Ｓｎ合金からなるエキスパンド格子をそれぞれ用い、通常の活物質を塗布した正極板５枚、負極板６枚を微細ガラス繊維セパレータを介して交互に積層し、電槽に挿入する。該蓄電池に所定量の希硫酸を注液して化成し、通常の安全弁を装着したいわゆるリテーナ式制御弁式鉛蓄電池を製作した。公称電圧および定格容量は、２Ｖ−２００Ａｈでこれらの蓄電池を２４セル直列に接続した。
【００２１】
まずこの組電池を種々の温度および電流で放電し、放電時の電圧とＳＯＣとの関係を示すデータテーブルを作成した。
【００２２】
この組電池を４０Ａで１．７Ｖまで放電した後、４０Ａ／５８．８Ｖの定電流・定電圧充電を行い、寿命性能を評価した。均等充電は、普通充電の時間をさらに６ｈ延長して行った。従来の蓄電池の場合はこの均等充電を１０サイクル毎に行い、本発明品は、従来品のように無理やり１０サイクル毎に行う、あるいは充電量が少ないのに１０サイクル経過するまで均等充電を待つというやり方ではなく、ＳＯＣの低下量１０％を一定のサイクル範囲内に到達するよう充電条件を随時変更する方式を実施した。
【００２３】
また、均等充電を３回連続したにもかかわらずＳＯＣが回復しない場合には、既に回復し得ない劣化が発生していると考えられるので、現時点の容量が１００％の容量であるとし、あらかじめ入力しているＳＯＣデータを修正した。修正によって、無理やり均等充電による過充電が頻繁に入ることを抑制した。
【００２４】
試験内容を表１に示す。また、蓄電池のＳＯＣは、本試験では、毎回の放電開始初期の放電電圧をあらかじめ測定しているＳＯＣ基準（ＳＯＣと放電電圧との関係データ）と比較することにより算出した。
【００２５】
【表１】

【００２６】
上記蓄電池において、Ｂ−１〜Ｄまでは、所定のサイクル数でＳＯＣが１０％以上低下しなかった場合は、充電時間を低減し、所定のサイクル数よりも早期に１０％以上もＳＯＣが低下した場合には充電時間を延長した。
【００２７】
図２は従来品、図４は本発明品の試験初期のＳＯＣ推移をそれぞれ示し、図３は従来品、図５は本発明品の充電量（放電電気量比）をそれぞれ示す。また、図６は従来品、図７は本発明品の寿命末期までの１００サイクル毎（均等充電後）の放電持続時間の推移をそれぞれ示す。
【００２８】
図２、図３および図６に示すように、単純に当初から設定したとおりの充電時間・均等充電を行っただけの従来蓄電池では、環境温度によって充電時間の変更を行ったが、その効果はあまりなく、５０℃では過充電傾向にあり、０℃では充電不足の傾向を示した。したがって、５０℃で試験した蓄電池（Ａ−３）は、減液量が多くなり、ドライアウトで寿命になったものと思われる。０℃の蓄電池（Ａ−２）は、毎回の充電量が不足し、活物質中に充電できない硫酸鉛が蓄積するいわゆるサルフェーションによる劣化が発生したものと予想でされる。３０℃で試験した蓄電池（Ａ−１）でも、サイクルと共にやや過充電量が多くなり、ドライアウトの傾向があった。これが寿命原因と思われる。均等充電を全くしない蓄電池（Ａ−１−１）では、やや充電量が不足している傾向が見られ、おそらく、サルフェーションが発生していると予想される。
【００２９】
一方、図４、図５および図７に示すように本発明の蓄電池（Ｂ−１〜Ｄ）ではＳＯＣが１０％低下した時点で均等充電を行うにあたって、所定のサイクル数範囲内で均等充電が行われるように随時充電時間を変更した。３０℃で試験した（Ｂ−１）の場合は、２１サイクル目から充電時間を２時間減らして調整を行った。また、０℃の（Ｂ−２）は当初から予定している充電時間で行えば、おおよそ２０サイクル以内に均等充電が入った。また、５０℃の（Ｂ−３）は、２０サイクル経過後も全くＳＯＣが低下しないため、充電時間を３時間減らした。その結果、上記の固定充電時間・固定均等充電を行った蓄電池（Ａ−１〜Ａ−３）に比べて、環境温度の影響が少なく蓄電池の状況に応じた制御がなされていることが理解できる。寿命性能も過充電が抑制された結果、大幅に改善されその効果が明らかになった。特に、環境温度５０℃の蓄電池は最初の２０サイクルでＳＯＣが１０％まで低下しなかったので、充電条件を変更し、２０サイクル以内にＳＯＣが１０％以下に低下するよう充電条件を変更することにより、５０℃にもかかわらず従来品に比べて大幅に寿命性能が改善された。
【００３０】
また、本試験では、５サイクルでＳＯＣが１０％以下になるもの（Ｃ）および２０サイクルまでＳＯＣが１０％以下にならないもの（Ｄ）も試験した。（Ｃ）は５サイクルで１％程度しかＳＯＣが低下しなかったので、６サイクル目からは充電時間を３時間少なくした。また、（Ｄ）は４０サイクル後もＳＯＣが４％しか低下しなかったので、さらに充電時間を３時間減らして調整した。
【００３１】
これら（Ｃ）および（Ｄ）の蓄電池は従来品に比べると寿命は良かったが、改善効果はそれほ大きくなく、５〜２０サイクルの範囲内でＳＯＣが１０％まで低下し、均等充電が入るように調整した蓄電池が最も長寿命であることがわかった。
【００３２】
鉛蓄電池の特性はサイクルと共に変化するので、固定された条件で充電を長期間行うと適切な充電が行えなくなり、過充電あるいは過放電をすることになり鉛蓄電池の劣化を早めることになる。本発明の充電制御方法のように、各蓄電池の特性を把握して（学習して）それを毎回の充電条件にフィードバックさせることにより過充電や過放電を避けて長寿命を達成できることが本試験で明らかになった。
【００３３】
なお、本実施例では、蓄電池のＳＯＣは、放電時の電圧データをあらかじめ制御システムに記録している基準データと比較して算出したが、電動車輌のように負荷が変動する用途では、種々の電流で放電した際の電圧値から、電流がゼロでの電圧、つまり開放電圧（無負荷電圧）を求め、蓄電池のＳＯＣを算出する方法も可能である。この場合は、機器あるいはシステム側にＳＯＣと開放電圧（無負荷電圧）との相関を示す基準データテーブルを準備しておく必要がある。また、放電時のＡｈ量あるいは走行距離（電動車輌の場合）と放電電圧や無負荷電圧とを比較し、両者の差や比率を均等充電直後を基準として、サイクルと共に発生する変化を追跡してＳＯＣの変化を測定することも可能である。
【００３４】
さらに、本発明ではあらかじめ基準データを入力し、基準データとの比較によりＳＯＣを判定したが、実際には、機器に搭載された状態で基準データを作成する方が精度が高い。よって、蓄電池が搭載された初期の一定期間に入力された放電データを用いてＳＯＣと放電電圧あるいは無負荷電圧との相関データテーブルを作成することがより実態に相応しており好ましい。
【００３５】
また均等充電直後のデータを常に基準データにし、均等充電毎にそれを更新していけば、蓄電池の経時変化をより正確に把握でき好ましい。
【００３６】
本実施例では、所定の温度の気相中で試験をおこなったが、実際には、組電池の所定場所のセルに温度センサーを装着する等して蓄電池の温度を測定しながらＳＯＣ判定を行うのが好ましい。
【００３７】
また、本発明では組電池全体の電圧・電流・温度の測定を行ってＳＯＣ判定をしたが、単セル、全セル、組電池での一定単位個数の蓄電池（ブロック）の電圧のデータを用いてＳＯＣを判定したり、それらのデータを組み合わせたり比較することによってより精度を高めることができる。
【００３８】
なお、本実施例では放電初期の電圧を用いてＳＯＣ判定を行ったが、ＳＯＣ判定はこの方法だけに限定されるものではなく、放電途中あるいは終期の電圧を用いてもよいし、放電電圧と電流との関係から算定した開放電圧（無負荷電圧）あるいは実測した開放電圧を用いてもよい。
【００３９】
【発明の効果】
本発明は、鉛蓄電池の寿命性能を改善するために、劣化の主要因である正極格子の腐食を抑制するにあたり、充電量を従来より少な目（９９〜１０２％目標）に設定し充電不足状態で使用し、それによるＳＯＣの低下量が１０％に到達した時点で均等充電を挿入するにあたって、例えば５〜２０サイクルの範囲内でＳＯＣが１０％低下するように充電条件を随時調整する方式を採用すると共に、上記ＳＯＣは放電時のデータとあらかじめ設定した基準データとの比較により求め、さらに前記均等充電後の放電データと基準データとを比較し、基準データを更新していくことによって蓄電池の履歴を学習しながら蓄電池の状態が制御できるので過充電が極力抑制でき、鉛蓄電池の寿命性能の向上・安定化に非常に有効でありその工業的効果は大である。
【図面の簡単な説明】
【図１】本発明の充電制御方法の実施例を示すブロック図
【図２】従来品の試験中のＳＯＣの推移を示す特性図
【図３】従来品の試験中の充電量の推移を示す特性図
【図４】本発明品の実施例の試験中のＳＯＣの推移を示す特性図
【図５】本発明品の実施例の試験中の充電量の推移を示す特性図
【図６】従来品の寿命特性（放電容量推移）を示す図
【図７】本発品の実施例の寿命特性（放電容量推移）を示す図[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a charge control method for a lead storage battery.
[0002]
[Prior art]
Lead storage batteries are used in various fields such as automobiles, stationary, electric vehicles, and solar power generation. In recent years, demand for high reliability and long life of such storage batteries has been increasing.
[0003]
The main cause of the deterioration of the lead-acid battery is corrosion of the positive electrode grid. That is, since the positive electrode grid is always in contact with the positive electrode active material having a high potential even in an open circuit state, it is in an environment where it is always corroded. Corrosion is further accelerated by charging overvoltage during charging. The grid has a function as a current collector and a function to retain an active material. However, if the corrosion progresses, these functions are reduced, and the capacity of the storage battery is reduced.
[0004]
Further, in particular, in a storage battery using a lead alloy substantially containing no Sb in the positive electrode grid, the amount of discharge is small, and in addition to the above-described corrosion problem in an overcharged use state, oxidation of the positive electrode grid proceeds too much, At the time of discharge, the portion is preferentially discharged, and a problem may occur that an insulating layer of lead sulfate is formed at the interface between the positive electrode grid and the active material and the capacity is reduced. In particular, when the frequency of discharge of the storage battery is high in order to level the external load as in the case of photovoltaic power generation, the effect is large.
[0005]
As a countermeasure against the above problem, it is important to suppress overcharging, but as the charged amount approaches 100% with respect to the discharged amount, electrolysis of water (H ₂ O =＝ O ₂ + H ₂₎ which is a side reaction. 2) The reactions occur in parallel, and the electric energy at the time of charging is used for this reaction, so that charging at 100% of the discharge amount causes a state of insufficient charging. Therefore, usually, overcharging of about 110% to 115% with respect to the discharge amount has to be performed, and it is clear that this overcharging is a cause of deterioration of the lead storage battery, and this overcharging is suppressed. Several charging methods have been proposed. For example, a two-stage constant-voltage charge is performed, and when the charge amount approaches 100% with respect to the first-stage charge voltage, the second-stage charge voltage is lowered, the charge current is reduced as much as possible, and the overcharge is performed. There are methods to avoid. Although this method has a certain effect, if a large number of lead-acid batteries are connected and used, the charging voltage is applied to all the storage batteries even if the charging voltage in the second stage is lowered. Even if the total charge voltage is low, there may be cases where high voltages are applied to individual storage batteries, and the effect of suppressing the overcharge by lowering the voltage in the second stage may be sufficient. May not be. Further, depending on the use environment temperature, even if the charging voltage is lowered, an overcharged state may not be avoided.
[0006]
In order to solve such a problem, the inventor does not control only the charging voltage in charging, but detects the state of charge (State of Charge, hereinafter referred to as SOC) of the storage battery, and changes the charging condition of the storage battery as needed based on the information. For example, it has been found that the above problems can be avoided, overcharging can be suppressed as much as possible, and this greatly contributes to improving the life of the lead storage battery. The present invention is based on the findings obtained thereby.
[0007]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to adjust the charging condition as needed based on information obtained by detecting the SOC of the lead storage battery, so that it is not affected by the variation of the storage battery and the temperature and conditions of the use environment, and is constantly constant. An object of the present invention is to provide a charge control method for charging an amount, suppressing overcharge, and obtaining a long-life lead-acid battery in cycle use.
[0008]
[Means for Solving the Problems]
Means for solving the problem is to reduce the amount of charge to 99 to 102% of the conventional amount of charge of 110 to 115% in order to minimize overcharging of the lead storage battery, thereby lowering the SOC. Claim 1 is based on a method of adjusting the charging condition of the storage battery so as to reduce the SOC to a predetermined SOC within a certain cycle when inserting the uniform charging at a time when the certain amount is lowered. For example, a first step of obtaining reference data indicating the relationship between the storage battery temperature, the discharge current, the discharge voltage and the SOC at the time of discharge, or the relationship between the storage battery temperature, the amount of discharge, and the SOC at the time of discharge;
A second step of discharging the storage battery;
A third step of measuring the storage battery temperature, the discharge current, the discharge voltage, and the number of cycles at the time of discharging in the second step, or the storage battery temperature, the amount of discharge, and the number of cycles at the time of discharging;
A fourth step of detecting the SOC based on a comparison between the measurement data in the third step and the reference data obtained in the first step,
When the amount of decrease in the SOC is less than a predetermined a% and the number of cycles is less than a predetermined value d, normal charging is performed, and the process returns to the second step.
When the amount of decrease in the SOC is less than a predetermined a% and the number of cycles is a predetermined value d, the second step is performed after changing the charging condition, resetting the number of cycles, and performing normal charging. Return to
When the amount of decrease in the SOC is equal to or more than a predetermined a% and the number of cycles is less than a predetermined value c, uniform charging is performed, and then discharging, changing charging conditions, resetting the number of cycles, After normal charging, return to the second step,
When the SOC decrease amount is equal to or more than a predetermined a% and the number of cycles is equal to or more than a predetermined c and less than d, equal charging and resetting of the number of cycles are performed, and the process returns to the second step. It is a feature.
[0009]
As described above, in order to prolong the life of a lead storage battery, how to suppress overcharging is an important factor, and the effect cannot be sufficiently obtained only by controlling the charging voltage as in the related art. Therefore, the inventor has determined the relationship between the storage battery temperature, current, and voltage (voltage of the assembled battery, voltage of the unit cell (cell), voltage of a fixed number of storage batteries (blocks) in the assembled battery) and the SOC, or The relationship between the storage battery temperature, the amount of discharged electricity (Ah), and the SOC is determined, and is introduced into the control system as reference data in advance, and the SOC of the storage battery in each cycle is detected by comparing the data with data obtained when the storage battery is discharged. At the same time, equalizing charge is inserted at the time when the SOC decreases from a state of insufficient charge of 100% or less to a predetermined value a%, for example, 10% from the set value. The period of the decrease is set in advance by the use period or the number of cycles, and the period or the number of cycles required for the SOC to decrease to the predetermined amount exceeds the range. If, it is determined that abnormal, adjusting the charging conditions so that SOC falls above a predetermined period of use or the number of cycles. In other words, the period during which the SOC decreases by 10% is set to, for example, 5 to 20 cycles, and if the SOC decreases to 10% or less earlier than this, it means that the insufficient charge is progressing more than expected, and is set. Take measures such as increasing the amount of charged Ah. If the SOC does not decrease to 10% or less after the elapse of 20 cycles, it is expected that the battery is used in an overcharged state. Therefore, measures such as reducing the set charge Ah amount are taken. With such a method, even if the device or the storage battery includes variations or inherent errors, the history during use is learned, and the charging condition is optimized from the relative data as described above. And it has a very effective effect on extending the life of the storage battery.
[0010]
As described above, when the storage battery is used in a low state where the SOC is 100% or less, when the SOC decreases by, for example, 10%, the charge for periodically returning to the original SOC is uniformly charged (refresh charge or recovery charge or the like). Also called).
[0011]
According to the second aspect, the reference data is corrected based on the discharge data acquired when the equal charging is performed.
[0012]
Since the storage battery changes over time with use, the SOC is always calculated by comparing it with the initially set reference data, and if the charging conditions are adjusted, correct judgment may not be made. If there is a difference between the SOC calculated from the voltage and the SOC calculated from the first reference data, the reference data is changed based on the data obtained from the uniform charging, and the reference is changed for each uniform charging. It is preferable to update the data.
[0013]
According to claim 3, the amount of decrease in the SOC detected in the fourth step is equal to or more than the predetermined value a% and the number of cycles is less than the predetermined value c despite the fact that the battery is evenly charged. When three times occur consecutively, the uniform charging condition and the reference data are changed.
[0014]
Despite the uniform charge, even if the equalized charge condition is changed after reaching the preset amount of decrease in SOC, for example, 10% or more, with the preset number of cycles, for example, less than 5 cycles, such a state occurs. If it occurs three times in a row, it means that the performance of the storage battery has deteriorated. Therefore, the previously input reference data is corrected. For example, the remaining capacity is 10% lower than that of a new battery. However, the SOC is adjusted by inputting information that the state of charge is 100%. By performing charging in accordance with such a deteriorated state, not only the overcharge than necessary is prevented, but also data on the remaining capacity and the degree of deterioration can be obtained from the above information.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is intended to suppress the corrosion of the positive electrode grid, which is a main cause of the deterioration of the storage battery, and to improve the life performance when the lead storage battery is used by being incorporated in an electric vehicle or equipment. In order to suppress overcharging of the lead storage battery as much as possible, the amount of charge was reduced to 99 to 102% as compared with the conventional amount of charge of 110 to 115%. A block diagram in a case where the present invention is actually operated, in which a method of adjusting a charging condition of a storage battery so as to decrease to a predetermined SOC within a certain cycle range when inserting uniform charging at a time point is used. Is shown in FIG.
[0016]
According to FIG. 1, the first step of obtaining reference data indicating the relationship between the storage battery temperature during discharging, the discharge current, the discharge voltage and the SOC, or the relationship between the storage battery temperature and the amount of discharge during discharging and the SOC, and discharging the storage battery A second step, a third step of measuring the storage battery temperature, discharge current, discharge voltage, and cycle number at the time of discharging in the second step, or a storage battery temperature, discharge amount, and cycle number at the time of discharging, and a third step And the fourth step of detecting the SOC by comparing the measurement data obtained in the first step with the reference data obtained in the first step. In this case, if the decrease in the SOC falls to 10% or less between 5 and 20 cycles, the SOC becomes equal. An example of performing charging will be described.
[0017]
First, if the SOC does not decrease by 10% in less than 20 cycles, normal charging is performed, and the process returns to the second step. If the SOC does not decrease to 10% or less after the elapse of 20 cycles, it is expected that the battery tends to be overcharged. Therefore, the charging conditions are changed, the number of cycles is reset, and normal charging is performed. Return to Next, when the SOC drops to 10% or less in less than 5 cycles, insufficient charging is expected. Therefore, after performing uniform charging and discharging, the charging conditions are changed, the number of cycles is reset, and normal charging is performed. Perform and return to the second step. The fourth case is a case where the SOC decreases by 10% in 5 cycles or more and less than 20 cycles, which means that the charging conditions are appropriate, and after performing the equal charging, the charging conditions are not changed. , The number of cycles is reset, and the process returns to the second step.
[0018]
By taking the above measures, even if the storage battery varies or the operating environment temperature and conditions are different, charging is always appropriate for the storage battery. .
[0019]
【Example】
In order to clarify the effect of the present invention, a detailed description will be given by a test based on an example.
[Test contents and results]
In conducting a test for clarifying the effect of the present invention, the following test storage batteries were manufactured.
[0020]
Each of the positive and negative plates is made of an expanded lattice made of a Pb-0.07 mass% Ca-1.3 mass% Sn alloy, and each of five positive plates and six negative plates coated with a normal active material is made of a fine glass fiber separator. Are alternately laminated through the container and inserted into a battery case. A predetermined amount of dilute sulfuric acid was injected into the storage battery to form a chemical, and a so-called retainer control valve type lead storage battery equipped with a normal safety valve was manufactured. Nominal voltage and rated capacity were 2 V-200 Ah, and these batteries were connected in series with 24 cells.
[0021]
First, the battery pack was discharged at various temperatures and currents, and a data table showing the relationship between the voltage at the time of discharging and the SOC was created.
[0022]
After discharging the assembled battery to 1.7 V at 40 A, the battery was charged at a constant current and a constant voltage of 40 A / 58.8 V, and the life performance was evaluated. The uniform charging was performed by extending the normal charging time by 6 hours. In the case of a conventional storage battery, this equal charging is performed every 10 cycles, and the product of the present invention is forcibly performed every 10 cycles like a conventional product, or waits for equal charging until 10 cycles elapse even though the charge amount is small. Instead of the method, a method of changing the charging condition as needed so that the SOC reduction amount reaches 10% within a certain cycle range was implemented.
[0023]
If the SOC does not recover even after three consecutive equalization charges, it is considered that deterioration that cannot be recovered has already occurred. Therefore, it is assumed that the current capacity is 100%, and The input SOC data was corrected. By the correction, it was suppressed that overcharging due to forcible uniform charging frequently entered.
[0024]
Table 1 shows the test contents. In this test, the SOC of the storage battery was calculated by comparing the discharge voltage at the beginning of each discharge with an SOC reference (data relating to the SOC and the discharge voltage) measured in advance.
[0025]
[Table 1]

[0026]
In the above storage battery, if the SOC does not decrease by 10% or more at the predetermined cycle number from B-1 to B-1, the charging time is reduced, and the SOC decreases by 10% or more earlier than the predetermined cycle number. If so, the charging time was extended.
[0027]
2 shows the SOC transition of the conventional product and FIG. 4 at the initial stage of the test of the product of the present invention. FIG. 3 shows the charge amount (discharge electricity ratio) of the conventional product and FIG. 5 respectively. FIG. 6 shows the transition of the discharge duration for every 100 cycles (after uniform charging) until the end of the life of the product of the present invention, and FIG.
[0028]
As shown in FIG. 2, FIG. 3, and FIG. 6, in the conventional storage battery in which the charging time and the uniform charging were simply performed as originally set, the charging time was changed depending on the environmental temperature. At 50 ° C., there was a tendency for overcharging, and at 0 ° C., there was a tendency for insufficient charging. Therefore, it is considered that the storage battery (A-3) tested at 50 ° C. had a large amount of liquid reduction and had a long life due to dryout. It is expected that the storage battery (A-2) at 0 ° C. has a shortage of charge every time and is deteriorated due to so-called sulfation, in which unrechargeable lead sulfate accumulates in the active material. Even in the storage battery (A-1) tested at 30 ° C., the overcharge amount slightly increased with the cycle, and there was a tendency for dryout. This seems to be the cause of the life. In the storage battery (A-1-1) that does not perform uniform charging at all, the charge amount tends to be slightly insufficient, and it is expected that sulfation has probably occurred.
[0029]
On the other hand, as shown in FIG. 4, FIG. 5, and FIG. 7, in the storage batteries (B-1 to D) of the present invention, when the SOC is reduced by 10%, the uniform charging is performed within a predetermined cycle number range. The charging time was changed as needed to be performed. In the case of (B-1) tested at 30 ° C., adjustment was performed by reducing the charging time by 2 hours from the 21st cycle. In addition, at (C-2) at 0 ° C., if the charging was performed for a predetermined charging time from the beginning, uniform charging was achieved within about 20 cycles. In the case of (B-3) at 50 ° C., the SOC did not decrease at all even after 20 cycles, so the charging time was reduced by 3 hours. As a result, it can be understood that compared to the storage batteries (A-1 to A-3) that have performed the fixed charging time and the fixed uniform charging, the influence of the environmental temperature is small and the control according to the state of the storage batteries is performed. . The life performance was also significantly improved as a result of suppressing overcharging, and the effect became clear. In particular, since the SOC did not decrease to 10% in the first 20 cycles of the storage battery at the environmental temperature of 50 ° C., change the charging conditions, and change the charging conditions so that the SOC decreases to 10% or less within 20 cycles. As a result, the life performance was significantly improved compared to the conventional product despite the fact that the temperature was 50 ° C.
[0030]
Further, in this test, those in which the SOC decreased to 10% or less in 5 cycles (C) and those in which the SOC did not decrease to 10% or less until 20 cycles (D) were also tested. In (C), the SOC decreased by only about 1% in 5 cycles, so the charging time was reduced by 3 hours from the 6th cycle. In (D), the SOC decreased by only 4% after 40 cycles, so the charging time was further reduced by 3 hours and adjusted.
[0031]
Although the storage batteries of (C) and (D) had a better life than the conventional products, the effect of improvement was not so great, and the SOC was reduced to 10% within the range of 5 to 20 cycles, and uniform charging was achieved. The storage battery adjusted in this way has the longest life.
[0032]
Since the characteristics of the lead storage battery change with the cycle, if the charging is performed under fixed conditions for a long period of time, appropriate charging cannot be performed, resulting in overcharging or overdischarging, leading to accelerated deterioration of the lead storage battery. As in the charge control method of the present invention, this test shows that the characteristics of each storage battery are grasped (learned) and fed back to each charging condition, thereby avoiding overcharging and overdischarging and achieving a long life. It became clear.
[0033]
In this embodiment, the SOC of the storage battery is calculated by comparing the voltage data at the time of discharging with reference data recorded in the control system in advance. It is also possible to calculate the SOC of the storage battery by calculating the voltage at which the current is zero, that is, the open-circuit voltage (no-load voltage) from the voltage value when the battery is discharged with the current. In this case, it is necessary to prepare a reference data table indicating the correlation between the SOC and the open circuit voltage (no-load voltage) on the device or system side. In addition, the amount of Ah at the time of discharge or the mileage (in the case of an electric vehicle) is compared with the discharge voltage or the no-load voltage, and the difference or ratio between the two is tracked based on the change immediately after the uniform charge to track the change that occurs with the cycle. It is also possible to measure changes in SOC.
[0034]
Further, in the present invention, the SOC is determined by inputting the reference data in advance and comparing the reference data with the reference data. However, in practice, the accuracy is higher when the reference data is created while being mounted on the device. Therefore, it is more preferable and more appropriate to create a correlation data table between the SOC and the discharge voltage or the no-load voltage using the discharge data input during the initial fixed period in which the storage battery is mounted.
[0035]
It is also preferable to always use the data immediately after the uniform charging as the reference data and to update the data every time the uniform charging is performed, so that the change with time of the storage battery can be more accurately grasped.
[0036]
In this embodiment, the test was performed in the gas phase at a predetermined temperature. However, actually, the SOC determination is performed while measuring the temperature of the storage battery by mounting a temperature sensor on a cell at a predetermined location of the assembled battery. Is preferred.
[0037]
Further, in the present invention, the SOC is determined by measuring the voltage, current, and temperature of the entire assembled battery. However, voltage data of a certain number of storage batteries (blocks) in single cells, all cells, and assembled batteries are used. The accuracy can be further improved by determining the SOC, combining or comparing those data.
[0038]
In the present embodiment, the SOC determination is performed using the voltage at the beginning of discharge. However, the SOC determination is not limited to this method, and the voltage during or at the end of discharge may be used. The open circuit voltage (no-load voltage) calculated from the relationship with the current or the actually measured open circuit voltage may be used.
[0039]
【The invention's effect】
According to the present invention, in order to improve the life performance of a lead storage battery, in suppressing the corrosion of the positive electrode grid, which is a main factor of deterioration, the charge amount is set to a smaller value (99 to 102% target) than in the prior art, and the state of charge is insufficient. When charging the battery with equal charge at the time when the SOC reduction amount reaches 10%, the charging condition is adjusted as needed so that the SOC decreases by 10% within the range of 5 to 20 cycles, for example. At the same time, the SOC is obtained by comparing the data at the time of discharging with reference data set in advance, and further compares the discharge data after the uniform charging with the reference data, and updates the reference data, thereby updating the history of the storage battery. The battery condition can be controlled while learning, so that overcharging can be suppressed as much as possible, which is very effective in improving and stabilizing the life performance of lead-acid batteries, and the industrial effect is great. A.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a charge control method of the present invention; FIG. 2 is a characteristic diagram showing transition of SOC during testing of a conventional product; FIG. 3 is a diagram showing transition of charging amount during testing of a conventional product; Characteristic diagram [FIG. 4] Characteristic diagram showing transition of SOC during test of an embodiment of the present invention [FIG. 5] Characteristic diagram showing transition of charge amount during test of an embodiment of the present invention [FIG. FIG. 7 is a diagram showing the life characteristics (discharge capacity transition) of a product. FIG. 7 is a diagram showing the life characteristics (discharge capacity transition) of an example of the present product.

Claims

A first step of obtaining reference data indicating a relationship between the storage battery temperature during discharging, a discharge current, a discharge voltage and SOC, or a relationship between storage battery temperature during discharging and a discharge amount and SOC;
A second step of discharging the storage battery;
A third step of measuring the storage battery temperature, the discharge current, the discharge voltage, and the number of cycles at the time of discharging in the second step, or the storage battery temperature, the amount of discharge, and the number of cycles at the time of discharging;
A fourth step of detecting an SOC based on a comparison between the measurement data in the third step and the reference data obtained in the first step,
When the amount of decrease in the SOC is less than a predetermined a% and the number of cycles is less than a predetermined value d, normal charging is performed, and the process returns to the second step.
When the amount of decrease in the SOC is less than a predetermined a% and the number of cycles is a predetermined value d, the second step is performed after changing the charging conditions, resetting the number of cycles, and performing normal charging. Return to
When the amount of decrease in the SOC is equal to or more than a predetermined a% and the number of cycles is less than a predetermined value c, equal charging is performed, and then discharging, changing charging conditions, resetting the number of cycles, After normal charging, return to the second step,
When the SOC decrease amount is equal to or more than a predetermined a% and the number of cycles is equal to or more than a predetermined c and less than d, equal charging and resetting of the number of cycles are performed, and the process returns to the second step. Features,
A method for controlling the charge of a lead storage battery.

2. The charge control method for a lead storage battery according to claim 1, wherein the reference data is corrected based on the discharge data obtained when the uniform charging is performed.

Despite the uniform charging, it is continuously determined that the amount of decrease in the SOC detected in the fourth step is equal to or more than a predetermined value a% and the number of cycles is less than a predetermined value c. The charge control method for a lead-acid battery according to claim 1 or 2, wherein when three times occur, the equal charge condition and the reference data are changed.