JP3702332B2

JP3702332B2 - Charge control method and charge control device for secondary battery

Info

Publication number: JP3702332B2
Application number: JP17241496A
Authority: JP
Inventors: 浩二山田
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1996-07-02
Filing date: 1996-07-02
Publication date: 2005-10-05
Anticipated expiration: 2016-07-02
Also published as: JPH1023684A

Description

【０００１】
【発明の属する技術分野】
本発明は二次電池の充電制御方法および充電制御装置に係り、さらに詳しくは定電流充電＋定電圧充電方式による充電制御方法および充電制御装置の改良に関する。
【０００２】
【従来の技術】
ニッケル−水素二次電池、ニッケル−カドミウムあるいはリチウムイオン二次電池などに代表される二次電池は、充電による電力の貯蔵、この貯蔵した電力を負荷の駆動源（放電）とする繰り返し動作が可能な電源として、たとえば携帯用電話機や携帯型撮像機など各種の機器システムに組み込まれたりして実用されている。
【０００３】
ところで、二次電池はいずれの場合も、前記したように、充電および放電が主要な機能であり、また効率および安全性の点から充電の終止電圧，放電の終止電圧をそれぞれ限界とし、この限界範囲内の電圧で充電や放電を行っている。そして、二次電池の充電制御方法として、定電流充電（定電流モード）および定電圧充電（定電圧モード）を組み合わせた方式が知られている。
【０００４】
この定電流充電＋定電圧充電方式では、図４に模式的に示すごとく、定電流モードでの充電を終了するための設定電池電圧値Ｖ_cvがあり、定電流モードで充電を進め、電池電圧が上昇して設定電池電圧値Ｖ_cvに到達した後は、定電圧で充電を行う定電圧モードに切り換え、所要の充電が行われる。ここで、設定電池電圧値Ｖ_cvは、充電初期の電池温度を検出し、予め設定されている電池温度および設定電池電圧値Ｖ_cvが定義付けられた表に従って設定される。そして、この定電流充電＋定電圧充電方式においては、電池の充電が満充電状態に近付くと充電電流値が低減化するので、充電電流値が所定の値以下になったときを充電終了時点としている。
【０００５】
なお、この充電制御方法の場合は、設定電池電圧値Ｖ_cvが高いと定電流モードでの充電が長時間継続して過充電状態となり易く、逆に、設定電池電圧値Ｖ_cvが低いと十分な充電容量が得られない（放電容量が低下）。こうした問題を踏まえて、通常定電流モードで90％程度までの充電を行い、残りの10％程度を定電圧モードで充電するように、設定電池電圧値Ｖ_cvを設定している。
【０００６】
【発明が解決しようとする課題】
しかし、従来の定電流充電＋定電圧充電方式では、実際上いろいろの問題がある。すなわち、被充電電池が新品であるか、あるいは中古品（寿命末期）であるかなどに拘らず、充電初期の電池温度を基準にして、定電流充電＋定電圧充電が行われる。図５は、一般的に、定電流充電＋定電圧充電に使用されている充電手段の回路構成を示すものである。
【０００７】
図５において、1a，1bは入力端子、２は定電流モードから定電圧モード充電に切り替える定電流・定電圧制御回路３によって制御されるスィッチ、４は充電電流検知回路部である。ここで、充電電流検知回路部４は、増幅器4aおよびＡ／Ｄコンバータ4bを備えた構成を成しており、検知した充電電流をマイコン５側に出力・表示する。また、６は被充電体としての二次電池で、充電端子7a，7bを介して充電手段（充電器）側に接続して行われている。
【０００８】
ところで、被充電電池が新品か中古品かによって、いわゆる内部インピーダンスに相違が生じ、充電初期時の電池温度や満充電電圧値が異なってくる。つまり、充電初期の電池温度を基準にして設定電池電圧値Ｖ_cvを設定し、定電流充電＋定電圧充電を行った場合、前記設定電池電圧値Ｖ_cvが適正であるときと、この設定電池電圧値Ｖ_cvでは充電不十分（未満充電）のときがある。たとえば、図６(a)に充電による電池電圧と充電時間との関係を、また、図６(b)にその充電時における充電電流と充電時間との関係をそれぞれ示すごとく、新品の場合（曲線Ａ，ａ）と中古品の場合（曲線Ｂ，ｂ）とは異なった態様を呈する。
【０００９】
すなわち、新品の場合は、充電電圧が設定電池電圧値Ｖ_cvに徐々に上昇する一方、この間一定の充電電流で充電が行われ、その後、充電電流が急激に低減して充電終了となる。これに対して、中古品の場合は、充電電圧が設定電池電圧値Ｖ_cvに急激に上昇し、この間一定の充電電流で充電が行われるが、その後、充電電流が徐々に低減して充電終了となる。ここで、中古品の場合、設定電池電圧値Ｖ_cvは、電池の内部インピーダンスを考慮していないため、前記設定電池電圧値Ｖ_cvに充電電圧が上昇した後の充電時間を比較的長く設定し、実質的に満充電の状態に充電される。
【００１０】
上記したように、従来の定電流充電＋定電圧充電方式の充電制御手段では、二次電池の使用経過によって、充電不十分な場合を生じたり、もしくは充電終了までに要する時間に大きな差が生じるという問題がある。こうした問題は、二次電池の効率的な使用（利用）を困難にするので、その改善・改良が望まれている。
【００１１】
本発明は上記事情に対処してなされたもので、被充電電池の使用経過などに関係なく、ほぼ一定の時間内に所要の充電を達成できる二次電池の充電制御方法およびその実施に適する充電制御装置の提供を目的とする。
【００１２】
【課題を解決するための手段】
請求項１の発明は、二次電池に設定電池電圧値Ｖcvまで定電流モードで充電した後、定電圧モードに移行して充電する二次電池の充電制御方法であって、充電開始から前記設定電池電圧値Ｖ cv に到達するまでの充電時間Ｔ_１を充電電圧が前記設定電池電圧値Ｖ cv に到達して充電電流が低下する際の充電電流の変化で検出し、前記充電時間Ｔ _１を、予め設定されている最適な設定電池電圧値Ｖcvに対応する充電時間Ｔ_Ａと比較し、前記充電時間Ｔ_１が充電時間Ｔ_Ａよりも短いときは、前記設定電池電圧値Ｖcvを上昇させ、定電流充電を行うことを特徴とする二次電池の充電制御方法である。
【００１３】
請求項２の発明は、設定電池電圧値Ｖcvで定電流モード充電から定電圧モード充電に移行する充電制御手段と、充電開始から前記設定電池電圧値Ｖ cv に到達するまでの充電時間Ｔ_１を、充電電圧が前記設定電池電圧値Ｖ cv に到達して充電電流が低下する際の充電電流の変化で検出する充電電流検知回路部と、前記検出した充電時間Ｔ_１が入力され、予めメモリーしている最適な設定電池電圧値Ｖcvに対応する充電時間Ｔ_Ａと比較する比較手段と、前記両充電時間の比較によって充電時間Ｔ_１が充電時間Ｔ_Ａよりも短いとき、前記設定電池電圧値Ｖcvを上昇させる設定電池電圧値変更手段とを有することを特徴とする二次電池の充電制御装置である。
【００１４】
すなわち、本発明の充電制御手段は、定電流充電＋定電圧充電方式において、充電の進行に伴う設定電池電圧値Ｖ_cvに到達した充電時間Ｔ₁と、前記設定電池電圧値Ｖ_cvに到達する最適な充電時間Ｔ_Aとを比較し、この比較に基づいて、要すれば前記設定電池電圧値Ｖ_cvを上げて、定電圧モードへの切り替え・変更時点を修正し、被充電電池の内部インピーダンス差に拘らず、常に、ほぼ一定の時間内での急速充電を可能にしたことを骨子としている。
【００１５】
請求項１の発明では、定電流充電開始時の電池温度を基準として設定した設定電池電圧値Ｖ_cvを、その後の定電流モード充電に伴う充電電圧が、前記設定電池電圧値Ｖ_cvに達するまでの時間によって、適正な設定電池電圧値Ｖ_cvに修正・変更される。すなわち、被充電電池は新品，中古品に拘らず最適な設定電池電圧値Ｖ_cvが設定されて、定電流モードの充電および定電圧モードの充電が行われ、適正な充電電圧の充電を、短い充電時間内に行うことができる。換言すると、いかなる二次電池の場合でも、充電時間が一定な急速充電器によって、所要の満充電を容易に実現できる。
【００１６】
請求項２の発明では、定電流モードの充電および定電圧モードの充電で、二次電池の経過に拘らず、適正な充電電圧の充電を短い充電時間内に行うことができる。
【００１７】
【発明の実施の形態】
以下、図１，図２および図３(a)， (b)を参照して実施の形態を説明する。
【００１８】
図１は、この発明に係る二次電池の充電制御装置の概略構成を示す回路図である。図１において、1a，1bは入力端子、２は定電流・定電圧制御回路３で制御されるスィッチ、４は充電電流検知回路部である。ここで、充電電流検知回路部４は、増幅器4aおよびＡ／Ｄコンバータ4bを備えた構成を成しており、検知した充電電流、充電の進行に伴う設定電池電圧値Ｖ_cvに到達するまでの充電時間Ｔ₁をマイクロコンピュータ５側に出力・表示する。なお、前記設定電池電圧値Ｖ cv に到達した段階で前記定電流モードの電流値を低下する際の充電電流が変化（低下）した時点で、定電流モードから定電圧モードに切り替えられる。
【００１９】
また、前記マイクロコンピュータ５は、被充電電池の種類ごとに定電流充電開始時の電池温度−設定電池電圧値Ｖ_cvの関係や、前記設定電池電圧値Ｖ_cvに達するまでの最適視される充電時間Ｔ_Aデータをメモリーするとともに、定電流充電開始から設定電池電圧値Ｖ_cvに到達するまでの充電時間Ｔ₁を読み込んで、充電時間Ｔ₁と充電時間Ｔ_Aとを比較し、この比較に基づいて、定電流・定電圧制御回路３の制御を行う。
【００２０】
すなわち、前記マイクロコンピュータ５と定電流・定電圧制御回路３とは、次のような並列な補正回路８で接続されている。ここで、補正回路８は、基準抵抗Ｒ_ref９に対して、補正抵抗Ｒ₁〜Ｒ_nおよびスイッチＳｗ₁〜Ｓｗ_nを直列に接続した並列回路を成している。そして、これら補正抵抗Ｒ₁〜Ｒ_nおよびスイッチＳｗ₁〜Ｓｗ_nの直列接続の選択組み合わせによって、定電流・定電圧制御回路３における制御は修正・変更される。
【００２１】
さらに詳述すると、補正回路８の使い分けによって、設定電池電圧値Ｖ_cvを１ステップごとに、たとえば約0.025Vの割合で上昇・変更できるようになっており、被充電電池の態様や充電条件に応じた設定電池電圧値Ｖ_cvにより、定電流モードから定電圧モードの充電に切り替えられる。
【００２２】
また、６は被充電体としての二次電池で、充電端子7a，7bを介して充電手段（充電器）側に接続される。
【００２３】
次に、上記充電制御装置によって、リチウム・イオン二次電池パックに、定電流モードおよび定電圧モードで充電制御する例を、図２のフローチャートおよび図３(a)の充電電圧特性曲線， (b)の充電電流特性曲線を参照して説明する。
【００２４】
先ず、定電流充電の開始に当たって、被充電電池６温度を測定して、対応する設定電池電圧値Ｖ_cvを設定し、定電流で充電を開始する。この定電流充電の進行に伴って、被充電電池６の電池電圧が順次上昇して、前記設定電池電圧値Ｖ_cvに到達する。設定電池電圧値Ｖ _cv に到達すると電圧上昇が止まり充電電流値は低下する。この電流値の低下による充電電流の変化は充電電流検知回路部４で検知される。ここで、充電電流が低下したと判断されると、この間の充電時間Ｔ₁がマイクロコンピュータ５に読み込まれ、マイクロコンピュータ５に予めメモリーしてある最適な充電時間Ｔ_Aと比較される。
【００２５】
すなわち、被充電電池６に対して最適視される充電時間Ｔ_Aに比べて、充電時間Ｔ₁が長い場合は、図３(a)， (b)で曲線Ｃおよび曲線ｃに示すように、設定電池電圧値Ｖ _cv での定電圧充電が続行する。
【００２６】
一方、前記比較において、充電時間Ｔ _A に比べて充電時間Ｔ ₁ が短い場合は、補正回路８の使い分けによって、設定電池電圧値Ｃ _cv が１ステップ上昇された形で、定電流・定電圧制御回路３の制御が行われる。すなわち、最適視される充電時間Ｔ_Aよりも充電時間Ｔ₁の方が短いときは、基準抵抗Ｒ_ref９に対して、並列、かつ複数の補正抵抗Ｒ₁〜Ｒ_nおよびスイッチＳｗ₁〜Ｓｗ_nの直列接続回路を、並列接続，オープンなど適宜選択し、前記設定電池電圧値Ｖ_cvを補正する。つまり、図３(a)， (b)で曲線Ｄおよび曲線ｄに示すように、定電流充電が定電圧充電に切り替えられる時点をズラし、再び定電流モードでの充電が続行され補正Ｖ _cv に到達してはじめて定電圧モードに移行し、補正Ｖ _cv での定電圧充電が行われる。その結果、定電圧モードの充電時間は大幅に短縮されることになる。
【００２７】
上記例示のごとく、対応する設定電池電圧値Ｖ_cvへの到達時点を定電流モード充電から定電圧モード充電に切り替え時点とする充電制御方式において、初めに設定した設定電池電圧値Ｖ_cvに定電流モード充電で到達する最適視される充電時間Ｔ_Aと実際の充電時間Ｔ₁とを比較して、これを目安（基準）として、設定電池電圧値Ｖ_cvを修正・変更して、効率的に定電流モードの充電および定電圧モードの充電が組み合わされるため、適正な充電を効率よく行うことができる。
【００２８】
また、定電流モード−定電圧モードの充電において、充電時の電池温度上昇も併せて測定し、電池の劣化状況に応じて設定電池電圧値Ｖ_cvを設定して、最適充電時間で充電終了するように制御できる。このとき、電池温度の上昇が新品電池の充電時温度の最大値の約２倍以上の場合は、電池自体の不良もしくは寿命末期と判断し、ユーザーに対し何らかの表示・警告を行うこともできる。つまり、電池寿命および以上判定の機能も実現できる。
【００２９】
なお、本発明は上記例示の場合に限定されるものでなく、発明の趣旨を逸脱しない範囲でいろいろの変形を採ることができる。たとえば、被充電電池は、リチウム・イオン二次電池パック以外のニッケル・水素二次電池パック，ニッケル・カドミウム二次電池パック、あるいはリチウム・イオン二次電池，ニッケル・水素二次電池，ニッケル・カドミウム二次電池など単一電池セルを対象とすることもできる。
【００３０】
【発明の効果】
以上説明から分かるように、請求項１および２の発明によれば、被充電用の二次電池に対する定電流モードの充電および低電圧モードの充電の実施において、被充電用二次電池の種別，しよう経過の如何に拘らず、効率よく満充電状態に近い充電を行うことができる。つまり、被充電電池が新品もしくは中古品であっても、適正な充電を確実に、また、定コストで行うことができるので、信頼性の高い携帯型電源の提供に大きく寄与することになる。
【図面の簡単な説明】
【図１】実施例の充電制御装置の概略構成を示す回路図。
【図２】実施例の充電制御法のフローチャート図。
【図３】実施例の充電制御法による充電時間と充電特性との関係を示し、 (a)電池電圧の変化図、 (b)は充電電流の変化図。
【図４】定電流モード充電−低電圧モード充電の一般的な実施態様を模式的に示す説明図。
【図５】従来の定電流モード充電−低電圧モード充電に用いる充電制御装置の概略構成を示す回路図。
【図６】従来充電制御法における被充電電池の新品，中古品と充電時間と充電特性との関係を示し、 (a)電池電圧の変化図、 (b)は充電電流の変化図。
【符号の説明】
1a，1b……電源端子
２……スイッチ
３……低電流・定電圧制御素子
４……充電電流検知回路部
4a……増幅器
4b…… A/Dコンバータ
５……マイクロコンピューター
６……電池パック
6a……電池セル
6b……温度検出素子
7a，7b……充電接続端子
８……補正回路
９……基準抵抗Ｒ_ref
Ｒ₁〜Ｒ_n……補正抵抗
Ｓｗ₁〜Ｓｗ_n……スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charge control method and a charge control device for a secondary battery, and more particularly to a charge control method using a constant current charge + constant voltage charge method and an improvement of the charge control device.
[0002]
[Prior art]
Secondary batteries represented by nickel-hydrogen secondary batteries, nickel-cadmium or lithium ion secondary batteries, etc., can store electric power by charging, and can be operated repeatedly using the stored electric power as a drive source (discharge) for the load. As a simple power source, for example, it has been put into practical use by being incorporated in various device systems such as a portable telephone and a portable imaging device.
[0003]
By the way, in any case, as described above, charging and discharging are the main functions of the secondary battery, and from the viewpoint of efficiency and safety, the end voltage of charging and the end voltage of discharging are the limits, respectively. Charging or discharging is performed at a voltage within the range. As a secondary battery charge control method, a method in which constant current charging (constant current mode) and constant voltage charging (constant voltage mode) are combined is known.
[0004]
In this constant current charging + constant voltage charging method, as schematically shown in FIG. 4, there is a set battery voltage value V _cv for ending charging in the constant current mode. Is increased to reach the set battery voltage value V _cv , switching to a constant voltage mode in which charging is performed at a constant voltage, and required charging is performed. Here, the set battery voltage value V _cv is set according to a table in which the battery temperature at the initial stage of charging is detected and the preset battery temperature and the set battery voltage value V _cv are defined. In this constant current charging + constant voltage charging method, the charging current value is reduced when the battery is almost fully charged. Therefore, when the charging current value becomes equal to or lower than a predetermined value, the charging end point is determined. Yes.
[0005]
In the case of this charge control method, if the set battery voltage value V _cv is high, charging in the constant current mode is likely to continue for an extended period of time, and conversely, if the set battery voltage value V _cv is low, it is sufficient. Charge capacity cannot be obtained (discharge capacity decreases). Based on these problems, the set battery voltage value V _cv is set so that charging up to about 90% is performed in the normal constant current mode, and the remaining 10% is charged in the constant voltage mode.
[0006]
[Problems to be solved by the invention]
However, the conventional constant current charging + constant voltage charging method has various problems in practice. That is, regardless of whether the battery to be charged is new or used (end of life), constant current charging + constant voltage charging is performed based on the battery temperature at the initial stage of charging. FIG. 5 shows a circuit configuration of charging means generally used for constant current charging + constant voltage charging.
[0007]
In FIG. 5, 1a and 1b are input terminals, 2 is a switch controlled by a constant current / constant voltage control circuit 3 for switching from constant current mode to constant voltage mode charging, and 4 is a charge current detection circuit section. Here, the charging current detection circuit unit 4 has a configuration including an amplifier 4a and an A / D converter 4b, and outputs and displays the detected charging current on the microcomputer 5 side. Reference numeral 6 denotes a secondary battery as an object to be charged, which is connected to the charging means (charger) side through charging terminals 7a and 7b.
[0008]
By the way, the so-called internal impedance varies depending on whether the battery to be charged is new or used, and the battery temperature and full charge voltage value at the initial stage of charging differ. That is, when the set battery voltage value V _cv is set based on the battery temperature at the initial stage of charging and constant current charging + constant voltage charging is performed, when the set battery voltage value V _cv is appropriate, the set battery voltage The voltage value V _cv may be insufficiently charged (less charged). For example, FIG. 6 (a) shows the relationship between battery voltage and charging time by charging, and FIG. 6 (b) shows the relationship between charging current and charging time at the time of charging. A, a) and second-hand goods (curves B, b) have different aspects.
[0009]
That is, in the case of a new product, the charging voltage gradually rises to the set battery voltage value _Vcv , while charging is performed with a constant charging current during this period, and thereafter, the charging current is rapidly reduced and charging ends. On the other hand, in the case of second-hand goods, the charging voltage suddenly rises to the set battery voltage value V _cv and charging is performed at a constant charging current during this time, but after that, the charging current gradually decreases and charging ends. It becomes. Here, in the case of a used product, the set battery voltage value V _cv does not consider the internal impedance of the battery, so the charging time after the charging voltage rises to the set battery voltage value V _cv is set to be relatively long. The battery is substantially fully charged.
[0010]
As described above, in the conventional constant current charge + constant voltage charge type charge control means, depending on the use of the secondary battery, there may be insufficient charge or there will be a large difference in the time required to complete the charge. There is a problem. Such a problem makes it difficult to efficiently use (use) the secondary battery. Therefore, improvement / improvement is desired.
[0011]
The present invention has been made in response to the above circumstances, and a secondary battery charge control method capable of achieving a required charge within a substantially constant time regardless of the usage of the battery to be charged and the charge suitable for the implementation thereof. The purpose is to provide a control device.
[0012]
[Means for Solving the Problems]
The invention according to claim 1, after charging at a constant current mode until set battery voltage Vcv the secondary battery, a charging control method for a secondary battery to charge shifts to the constant voltage mode, the setting of the charging start detecting a change in the charging current when the charging time T ₁ of the to reach the battery voltage value V cv charging voltage decreases to the charging current reaches the set battery voltage value V cv, the charging time T ₁ , compared to the charging time T _a corresponding to the optimum setting battery voltage Vcv which is set in advance, when the charging time T ₁ is shorter than the charging time T _a is increased the setting battery voltage Vcv, A charge control method for a secondary battery, wherein constant current charging is performed.
[0013]
A second aspect of the present invention, a charge control means to shift from the constant current mode charging by setting battery voltage Vcv constant voltage mode charging, charging time from start of charging until reaching the set battery voltage value V cv T ₁ is input with a charge current detection circuit unit that detects a change in charge current when the charge voltage reaches the set battery voltage value V cv and the charge current decreases, and the detected charge time T ₁ is input in advance. when comparing means for comparing the charging time T _a corresponding to the optimum setting battery voltage Vcv that memory is shorter than the charging time T ₁ by comparison of both the charging time charging time T _a, the setting battery voltage A charge control device for a secondary battery, comprising: a set battery voltage value changing means for increasing the value Vcv.
[0014]
That is, the charge control unit of the present invention, in the constant current charging + constant voltage charging method, the charging time T ₁ that has reached the set battery voltage value V _cv with the progress of charge, reaches the set battery voltage value V _cv comparing the optimal charging time T _a, based on this comparison, raise the setting battery voltage value V _cv optionally, modify the switching or change the time to the constant voltage mode, the internal impedance of the rechargeable battery Notwithstanding the differences, always has the gist that enables rapid charging substantially within a certain time.
[0015]
According to the first aspect of the present invention, the set battery voltage value V _cv set based on the battery temperature at the start of constant current charging is used until the charging voltage associated with the subsequent constant current mode charging reaches the set battery voltage value V _cv. The battery voltage value V _cv is corrected / changed to an appropriate setting depending on That is, regardless of whether the battery to be charged is new or used, an optimal set battery voltage value V _cv is set, charging in a constant current mode and charging in a constant voltage mode are performed, and charging with an appropriate charging voltage is short. It can be done within the charging time. In other words, for any secondary battery, the required full charge can be easily realized by a quick charger with a constant charging time.
[0016]
According to the second aspect of the present invention, it is possible to perform charging with an appropriate charging voltage within a short charging time regardless of the progress of the secondary battery by charging in the constant current mode and charging in the constant voltage mode.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment will be described below with reference to FIGS. 1, 2 and 3 (a), 3 (b).
[0018]
FIG. 1 is a circuit diagram showing a schematic configuration of a charge control device for a secondary battery according to the present invention. In FIG. 1, 1a and 1b are input terminals, 2 is a switch controlled by a constant current / constant voltage control circuit 3, and 4 is a charging current detection circuit section. Here, the charging current detection circuit unit 4 has a configuration including an amplifier 4a and an A / D converter 4b. The charging current detection circuit unit 4 reaches the set battery voltage value V _cv as the charging progresses. The charging time T ₁ is output and displayed on the microcomputer 5 side. It should be noted that the constant current mode is switched to the constant voltage mode when the charging current at the time of decreasing the current value in the constant current mode changes (decreases) when reaching the set battery voltage value Vcv .
[0019]
Further, the microcomputer 5, the battery temperature at the time of constant current charging started for each type of the rechargeable battery - Rechargeable being the optimum viewing up relationships and setting the battery voltage value V _cv, reaches the set battery voltage value V _cv as well as memory the time T _a data, reads the charging time T ₁ of the to reach the set battery voltage value V _cv from the constant current charging started, compared with the charging time T ₁ charge time T _a, the comparison Based on this, the constant current / constant voltage control circuit 3 is controlled.
[0020]
That is, the microcomputer 5 and the constant current / constant voltage control circuit 3 are connected by a parallel correction circuit 8 as follows. Here, the correction circuit 8 forms a parallel circuit in which correction resistors R _{1 to} R _n and switches Sw _{1 to} Sw _n are connected in series to the reference resistor R _ref 9. Then, depending on selection combination of the series connection of these correction resistor R ₁ to R _n and the switch Sw ₁ to SW _n, the control in the constant current and constant voltage control circuit 3 is modified or changed.
[0021]
More specifically, the set battery voltage value V _cv can be increased or changed at a rate of about 0.025 V, for example, at a rate of about 0.025 V by properly using the correction circuit 8. The charging is switched from the constant current mode to the constant voltage mode according to the corresponding set battery voltage value _Vcv .
[0022]
Reference numeral 6 denotes a secondary battery as an object to be charged, which is connected to the charging means (charger) side through charging terminals 7a and 7b.
[0023]
Next, an example in which the charge control device performs charge control on the lithium ion secondary battery pack in the constant current mode and the constant voltage mode will be described with reference to the flowchart of FIG. 2 and the charge voltage characteristic curve of FIG. This will be described with reference to a charging current characteristic curve of
[0024]
First, at the start of constant current charging, the temperature of the battery 6 to be charged is measured, a corresponding set battery voltage value V _cv is set, and charging is started at a constant current. As the constant current charging progresses, the battery voltage of the battery 6 to be charged sequentially increases and reaches the set battery voltage value _Vcv . When the set battery voltage value V _cv is reached, the voltage increase stops and the charging current value decreases. A change in the charging current due to the decrease in the current value is detected by the charging current detection circuit unit 4. Here, the charging current is judged to have lowered, the charging time T ₁ of the between this is read into the microcomputer 5, Ru is compared with the optimum charging time T _A that is previously memory in the microcomputer 5.
[0025]
That is, when the charging time T ₁ is longer than the charging time T _A that is optimal for the battery 6 to be charged, as shown in the curves C and c in FIGS. 3 (a) and 3 (b), Constant voltage charging at the set battery voltage value V _cv continues.
[0026]
On the other hand, in the comparison, when the charging time T ₁ is shorter than the charging time T _A , constant current / constant voltage control is performed in such a manner that the set battery voltage value C _cv is increased by one step by properly using the correction circuit 8. The circuit 3 is controlled. That is, when the charging time T ₁ is shorter than the optimal charging time T _A , a plurality of correction resistors R _{1 to} R _n and switches Sw _{1 to} Sw and parallel to the reference resistor R _ref 9 are provided. _{The n} series connection circuit is appropriately selected such as parallel connection or open, and the set battery voltage value V _cv is corrected. That is, as shown by curves D and d in FIGS. 3A and 3B, the time point at which constant current charging is switched to constant voltage charging is shifted, charging in constant current mode is continued again, and correction V _{cv is performed.} Only when the voltage reaches the constant voltage mode, the mode shifts to the constant voltage mode, and the constant voltage charging with the correction V _cv is performed. As a result, the charging time in the constant voltage mode is greatly shortened.
[0027]
As illustrated above, in the charge control method in which the time point when the corresponding set battery voltage value _Vcv is reached is switched from constant current mode charging to constant voltage mode charging, the constant current is set to the initially set battery voltage value _Vcv. Comparing the optimal charging time T _A reached by mode charging with the actual charging time T _1, and using this as a guideline (reference), the set battery voltage value V _cv is corrected / changed for efficient Since charging in the constant current mode and charging in the constant voltage mode are combined, appropriate charging can be performed efficiently.
[0028]
Moreover, in charging in the constant current mode-constant voltage mode, the battery temperature rise at the time of charging is also measured, the set battery voltage value V _cv is set according to the deterioration state of the battery, and the charging is completed in the optimum charging time. Can be controlled. At this time, if the rise in the battery temperature is about twice or more the maximum value of the charging temperature of the new battery, it is determined that the battery itself is defective or at the end of its life, and some display / warning can be given to the user. That is, the battery life and the determination function can be realized.
[0029]
In addition, this invention is not limited to the case of the said illustration, A various deformation | transformation can be taken in the range which does not deviate from the meaning of invention. For example, the rechargeable battery may be a nickel / hydrogen secondary battery pack other than a lithium / ion secondary battery pack, a nickel / cadmium secondary battery pack, or a lithium / ion secondary battery, a nickel / hydrogen secondary battery, or a nickel / cadmium battery. A single battery cell such as a secondary battery can also be targeted.
[0030]
【The invention's effect】
As can be seen from the above description, according to the inventions of claims 1 and 2, in the charging of the constant current mode and the charging of the low voltage mode for the secondary battery to be charged, the type of the secondary battery to be charged, Regardless of the progress, it is possible to efficiently perform charging close to a fully charged state. That is, even if the battery to be charged is new or used, proper charging can be performed reliably and at a constant cost, which greatly contributes to the provision of a highly reliable portable power source.
[Brief description of the drawings]
FIG. 1 is a circuit diagram illustrating a schematic configuration of a charge control device according to an embodiment.
FIG. 2 is a flowchart of a charge control method according to the embodiment.
FIGS. 3A and 3B show a relationship between a charging time and a charging characteristic according to the charging control method of the embodiment, wherein FIG. 3A is a change diagram of a battery voltage, and FIG.
FIG. 4 is an explanatory diagram schematically showing a general embodiment of constant current mode charging-low voltage mode charging.
FIG. 5 is a circuit diagram showing a schematic configuration of a conventional charge control device used for constant current mode charge-low voltage mode charge.
FIG. 6 shows the relationship between new and used batteries to be charged and charging time and charging characteristics in the conventional charging control method, (a) battery voltage change diagram, (b) charge current change diagram.
[Explanation of symbols]
1a, 1b …… Power supply terminal 2 …… Switch 3 …… Low current / constant voltage control element 4 …… Charging current detection circuit
4a …… Amplifier
4b ... A / D converter 5 ... Microcomputer 6 ... Battery pack
6a …… Battery cell
6b …… Temperature detection element
7a, 7b: Charging connection terminal 8: Correction circuit 9: Reference resistance R _ref
R _{1 to} R _n …… Correction resistance Sw _{1 to} Sw _n ...... Switch

Claims

A charge control method for a secondary battery in which a secondary battery is charged in a constant current mode up to a set battery voltage value Vcv and then transferred to a constant voltage mode and charged.
Detecting a change in the charging current when it reaches the charging time T ₁ to the charging voltage the set battery voltage value V cv charging current to reach the set battery voltage value V cv start of charging is lowered,
The charging time T _1, as compared to the charging time T _A corresponding to the optimum setting battery voltage Vcv which is set in advance,
When said charging time T ₁ is shorter than the charging time T _A, the raising of the set battery voltage Vcv, charging control method for a secondary battery and performing constant current charging.

A charging control means to shift from the setting battery voltage constant current mode charging by Vcv constant voltage mode charging,
The charging time T ₁ of the start of charging until reaching the set battery voltage value V cv, charge current the charging voltage reaches the set battery voltage value V cv detects a change of the charging current at the time of drop charging A current detection circuit section;
Comparison means for charging time T ₁ that the detection is inputted, compares the charging time T _A corresponding to the optimum setting battery voltage Vcv that advance memory,
When said charging time T ₁ by comparison of both the charging time is shorter than the charging time T _A, the charge control of a secondary battery characterized by having a set battery voltage value changing means for increasing said set battery voltage Vcv apparatus.