JP3829441B2

JP3829441B2 - Secondary battery control device, battery pack provided with secondary battery control device, and secondary battery control method

Info

Publication number: JP3829441B2
Application number: JP30185397A
Authority: JP
Inventors: 文哉佐藤
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1997-11-04
Filing date: 1997-11-04
Publication date: 2006-10-04
Anticipated expiration: 2017-11-04
Also published as: JPH11146570A

Description

【０００１】
【発明の属する技術分野】
本発明は、２次電池の制御装置、２次電池の制御装置を備えた電池パック及び２次電池の制御方法の改良、特に２次電池の充電容量及び放電容量を向上させる２次電池の制御装置、２次電池の制御装置を備えた電池パック及び２次電池の制御方法に関する。
【０００２】
【従来の技術】
携帯式パーソナルコンピュータ、携帯電話、ビデオカメラ等には、リチウムイオン電池やニッケルカドミウム電池、ニッケル水素電池等の充電式の電池（２次電池）が用いられている。２次電池とは、放電後に外部からエネルギーを供給することにより再生できる電池のことをいう。
２次電池は、ケースに収容されている場合があり、そのケースの中には複数個の２次電池が例えば直列に接続されている。このケースの外周面には外部端子が設けられており、外部端子に充電装置、あるいは携帯電話等の電子機器が接続することにより、２次電池は充電あるいは放電を行う。
【０００３】
図５は、従来の電池パック１０のシステム図を示している。図５の電池パック１は、２次電池２、保護部３、スイッチ手段４、抵抗器５、外部端子６等を有している。
２次電池２は例えば２個の２次電池セル２ａ、２ｂからなっており、２次電池セル２ａ、２ｂは直列に配置されている。２次電池セル２ａ、２ｂには外部端子６が接続されていて、２次電池セル２ａ、２ｂの間には抵抗器５を介して保護部３が接続されている。スイッチ手段４はスイッチ素子４ａ、４ｂからなっており、２次電池セル２ａ、２ｂにそれぞれ並列に接続されている。スイッチ手段８は、スイッチ素子８ａ、８ｂで構成されている。スイッチ手段８は外部端子６と２次電池セル２ａ、２ｂとの間に設けられており、保護部３によりスイッチング動作を制御されている。保護部３は、過充電保護部３ａと過放電保護部３ｂとからなっており、２次電池セル２ａ、２ｂが過剰の充電もしくは放電が行われないようにしている。
【０００４】
この電池パック１の充電は、外部端子６に対して充電電圧Ｖｃを印加し、２次電池セル２ａ、２ｂに対して充電電圧Ｖｃを供給することにより行われる。このとき、過充電保護部３ａは２次電池セル２ａ、２ｂのそれぞれの電池電圧Ｖ１、Ｖ２を測定している。そして、２次電池セル２ａ、２ｂの充電が終了したことを過充電保護部３ａが判断すると、過充電保護部３ａはスイッチ素子８ａを開いて、２次電池セル２ａ、２ｂに対して充電電圧Ｖｃの供給を停止する。
【０００５】
２次電池セル２ａ、２ｂに充電が終了したことの判断するために、過充電保護部３ａには２次電池セル２ａ、２ｂが基準電圧Ｖｒに達したとき充電を停止するように設定されている。２次電池セル２ａ、２ｂの電池容量に差異がある場合（２ａ＞２ｂ）、電池容量の小さい２次電池セル２ｂはより早く充電を終了する。このため、２次電池セル２ｂの電池電圧Ｖ２が過充電保護部３ａの基準電圧Ｔｒに到達したとき充電が終了し、２次電池セル２ａは完全に充電が行われない。従って、充電時に２次電池セルの電池電圧を放電して、各電池電圧の平準化を図る必要がある。
【０００６】
そこで、２次電池セル２ａが過充電保護部３ａの基準電圧Ｖｒを上回ったとき、過充電保護部３ａがスイッチ素子４ａを閉じる。これにより、２次電池セル２ｂの電池電圧が抵抗器５により基準電圧Ｖｒ以下まで放電され、２次電池セル２ａと２次電池セル２ｂの電池電圧Ｖ１、Ｖ２の平準化を行う。その後、スイッチ素子４ａが開かれて、充電が再開される。
【０００７】
【発明が解決しようとする課題】
しかし従来、過充電保護部３ａは電池電圧Ｖ１、Ｖ２が基準電圧Ｖｒまで達しないと、過充電保護機能が作動しなかった。すなわち、充電時に２次電池セル２ｂの電池電圧Ｖ２が過充電保護部３ａの基準電圧Ｖｒに到達したときに充電が終了してしまい、２次電池セル２ａには十分な充電ができず、２次電池セル２ａの電池容量が効率的に利用できないという問題がある。
【０００８】
また放電時において、２次電池セル２ａ、２ｂの電池容量に差異がある場合、電池容量の一番小さいセルの電池電圧が過放電保護部３ｂの基準電圧Ｖｒに到達したときに放電が終了していた。すなわち、従来において、充電時における２次電池セル２ａ、２ｂの平準化を行う機能を有するものはあったが、２次電池セルの放電時に２次電池セル２ａ、２ｂの平準化を行う機能を有するするものはなかった。これにより、電池容量の大きい２次電池セルに充電されている電池電圧が完全に使い切ることができず、放電効率が悪いという問題がある。
【０００９】
そこで本発明は上記課題を解消し、２次電池を効率よく充電あるいは放電させる２次電池の制御装置及びそれを用いた電池パックを提供することを目的としている。
【００１０】
【課題を達成するための手段】
上述の目的を達成するため、本発明は、直列に接続された複数の２次電池セルと、各２次電池セルに充電電圧を供給し、または各２次電池セルから放電電圧が供給される外部端子と、外部端子から供給される充電電圧及び外部端子に供給する放電電圧を制御する保護部とを有する２次電池の制御装置において、各２次電池セルにそれぞれ並列に接続されている複数のスイッチ素子からなるスイッチ手段と、各２次電池セルの電池電圧を測定し、その測定値に基づいてスイッチ手段のスイッチング動作を制御するバランス検出部と、スイッチ素子とスイッチ素子の間に設けられており、各スイッチ素子のスイッチング動作により、各２次電池セルと並列に接続される蓄電部とを有し、上記バランス検出部には、平準基準電圧値が設定されており、複数の２次電池セルの中で、電池電圧の最も高い２次電池セルと最も低い２次電池セルを検出し、電池電圧の最も高い２次電池セルと最も低い２次電池セルの電位差と平準基準電圧値を比較し、その電位差が平準基準電圧値より大きい場合、最も電池電圧の高い２次電池セルに蓄電部を接続して、蓄電部に充電を行い、
最も電池電圧の高い２次電池セルから最も電池電圧の低い２次電池セルに蓄電部の接続を切り替えて、蓄電部から最も電池電圧の低い２次電池セルに充電を行い、その電位差が平準基準電圧値より小さくなるまで、蓄電部の接続の切り替えを繰り返すようにしたものである。
【００１１】
本発明では、各２次電池の電池電圧をバランス検出部が測定し、各２次電池の電圧差を計算する。その電圧差の値に基づいてバランス検出手段がスイッチ手段のスイッチング動作を制御する。スイッチ手段の動作により、蓄電部が各２次電池セルと並列に接続されて、各２次電池セルは蓄電池に対して電池電圧の放電、もしくは充電を行う。これにより、それぞれの２次電池セルの電池電圧を平準化を行う。
これにより、２次電池が充電もしくは放電をするに際し、各２次電池セルの電池電圧をほぼ同じに保てるので、効率よく充電もしくは放電ができる。また、２次電池の平準化を効率よく行うことができる。
【００１２】
また、本発明は、直列に接続されている複数の２次電池セルに対して充電電圧を供給し、または各２次電池セルに蓄えられている電力を外部に放電する２次電池の制御方法において、複数の２次電池セルの中で、電池電圧の最も高い２次電池セルと最も低い２次電池セルを検出し、電池電圧の最も高い２次電池セルと最も低い２次電池セルの電位差と平準基準電圧値を比較し、その電位差が平準基準電圧値より大きい場合、最も電池電圧の高い２次電池セルに蓄電部を接続して、蓄電部に充電を行い、最も電池電圧の高い２次電池セルから最も電池電圧の低い２次電池セルに蓄電部の接続を切り替えて、蓄電部から最も電池電圧の低い２次電池セルに充電を行い、その電位差が平準基準電圧値より小さくなるまで、蓄電部の接続の切り替えを繰り返すようにしたものである。
【００１３】
本発明では、蓄電部を用いて最も電池電圧が高い２次電池セルから最も電池電圧が低い２次電池セルに対して充電を行う。これにより、２次電池が充電もしくは放電をするに際し、各２次電池セルの電池電圧をほぼ同じに保てるので、効率よく充電もしくは放電ができる。また、２次電池の平準化を効率よく行うことができる。
【００１４】
【発明の実施の形態】
以下、本発明の好適な実施の形態を添付図面に基づいて詳細に説明する。
なお、以下に述べる実施の形態は、本発明の好適な具体例であるから、技術的に好ましい種々の限定が付されているが、本発明の範囲は、以下の説明において特に本発明を限定する旨の記載がない限り、これらの形態に限られるものではない。
【００１５】
図１には本発明の２次電池の制御装置を備えた電池パックの実施形態の概念図を示しており、図１を参照して電池パック１０について詳しく説明する。図１の電池パック１０は、２次電池１１、外部端子１２、制御装置１３等を有している。
２次電池１１は例えば２個の２次電池セル１１ａ、１１ｂからなっており、２次電池セル１１ａ、１１ｂは直列に配置されている。２次電池セル１１ａ、１１ｂは、例えばリチウムイオン電池、ニッケルカドミウム電池、ニッケル水素電池等からなっており、２次電池１１は外部端子１２と接続されている。
外部端子１２に充電装置が接続されると、２次電池セル１１ａ、１１ｂに充電電圧Ｖｃが供給され、外部端子１２に電子機器等が接続されると、２次電池セル１１ａ、１１ｂが電子機器に対して放電電圧Ｖｄを供給する。
【００１６】
２次電池セル１１ａ、１１ｂと外部端子１２の間には制御装置１３が配置されている。制御装置１３は、保護部１４、バランス検出部１５、スイッチ手段１６、蓄電部であるコンデンサ１７等を有している。
保護部１４は過充電保護部１４ａと過放電保護部１４ｂとからなっている。過充電保護部１４ａはスイッチ素子１８ａに接続されており、そのスイッチング動作を制御している。また、過放電保護部１４ｂはスイッチ素子１８ｂに接続されており、そのスイッチング動作を制御している。過充電保護部１４ａには上限基準電圧Ｖｒ１が設定されており、過放電保護部１４ｂには下限基準電圧Ｖｒ２が設定されている。
過充電保護部１４ａは、電池電圧Ｖ１、Ｖ２が上限基準電圧Ｖｒ１より高くなると、充電を終了するために、スイッチ素子１８ａを開いて充電を停止する。また、過放電保護部１４ｂは電池電圧Ｖ１、Ｖ２が下限基準電圧Ｖｒ２より低くなると、スイッチ素子１８ｂを開いて放電を停止する。
【００１７】
次に、バランス検出部１５について詳しく説明する。
バランス検出部１５は、２次電池セル１１ａ、１１ｂの両端にそれぞれ接続されている。また、バランス検出部１５は後述するスイッチ手段１６と接続されており、そのスイッチング動作を制御している。また、バランス検出部１５には、平準基準電圧Ｖｒ３が設定されている。
バランス検出部１５は各２次電池セル１１ａ、１１ｂのそれぞれの電池電圧Ｖ１、Ｖ２を測定し、その電圧差ΔＶを検出する。そして、その電位差ΔＶと平準基準電圧Ｖｒ３とを比較し、その結果に応じてスイッチ手段１６のスイッチングを制御する。
【００１８】
バランス検出部１５の両端にはスイッチ手段１６が並列に接続されている。スイッチ手段１６は複数のスイッチ素子１６ａ、１６ｂで構成されており、例えば、電磁リレー、電解効果トランジスタ（ＦＥＴ）、フォトＭＯＳリレーからなっている。スイッチ素子１６ａ、１６ｂは２次電池セル１１ａ、１１ｂの両端にそれぞれ接続されている。スイッチ素子１６ａ、１６ｂの間にはコンデンサ１７が設けられている。コンデンサ１７は、セラミックコンデンサ、フィルムコンデンサ、電解コンデンサ、電気２重層コンデンサ等からなっている。また、コンデンサ１７の代わりに、２次電池を使用してもよい。
スイッチ素子１６ａ、１６ｂが端子ａに接続されると、コンデンサ１７は２次電池セル１１ａと並列に接続され、端子ｂに接続されると、コンデンサ１７は２次電池セル１１ｂと並列に接続される。
【００１９】
次に、図１乃至図４を参照して、２次電池セル１１ａ、１１ｂが充電される過程について詳しく説明する。
外部端子１２に充電電圧Ｖｃが外部から供給され、２次電池セル１１ａ、１１ｂに充電電圧Ｖｃが印加される。このとき、保護部１４はスイッチ手段１８を閉じた状態に保っている。そして、２次電池セル１１ａ、１１ｂの電池電圧Ｖ１、Ｖ２はバランス検出部１５により測定されている。そして、２次電池セル１１ａ、１１ｂの充電が終了すると、過充電保護部１４ａがスイッチ素子１８ａを開いて、充電を停止する。２次電池セル１１ａ、１１ｂに過剰の充電あるいは放電を防止し、２次電池セル１１ａ、１１ｂの劣化による放電容量の減少、内部ショートを防ぐことができる。
【００２０】
ここで、２次電池セル１１ａと１１ｂのそれぞれの電池容量Ｃ１、Ｃ２に差異がある場合（Ｃ１＜Ｃ２）、２次電池セル１１ａの電池電圧Ｖ１は２次電池セル１１ｂの電池電圧Ｖ２より高くなる。そして、バランス検出部１５はこの電池電圧Ｖ１、Ｖ２を比較して、その電圧差ΔＶを測定する。そして、バランス検出部１５は電圧差ΔＶと平準基準電圧Ｖｒ３を比較する。電圧差ΔＶが平準基準電圧Ｖｒ３より小さいとき（ΔＶ＜Ｖｒ３）、バランス検出部１５はスイッチ手段１６を作動させずに、端子ａ、ｂのいずれにも接続しない状態を保つ。これにより、２次電池セル１１ａ、１１ｂには通常の充電電圧Ｖｃが供給され、充電が行われる。
【００２１】
これに対し、電位差ΔＶが平準基準電圧Ｖｒ３より大きくなったとき（ΔＶ＞Ｖｒ３）、バランス検出部１５がスイッチ素子１６ａ、１６ｂを端子ａに接続させ、図２に示すように、コンデンサ１７を２次電池セル１１ａと並列に接続させる。すると、コンデンサ１７の電圧Ｖ３は、電池電圧Ｖ１と同じになり（Ｖ３＝Ｖ１）、コンデンサ１７には電荷Ｑが蓄えられる。このとき、２次電池２次電池セル１１ａはコンデンサ１７に対して放電している状態となる。これにより、２次電池セル１１ａの電池電圧Ｖ１を下げることができる。
【００２２】
次に、Ｖ３＝Ｖ１となったとき、バランス検出部１５はスイッチ素子１６ａ、１６ｂを端子ｂに接続させる。すると、図３に示すように、コンデンサ１７が２次電池セル１１ｂと並列に接続される状態となる。そして、コンデンサ１７の電圧Ｖ３は、電池電圧Ｖ２と同じになる（Ｖ３＝Ｖ２）。このとき、コンデンサ１７の電圧Ｖ３は電圧Ｖ１からＶ２に下がるため、２次電池セル１１ｂはコンデンサ１７によって充電されている状態となる。これにより、２次電池セル１１ｂの電池電圧Ｖ２を上げることができる。
【００２３】
そして、バランス検出部１５は、図４に示すように、端子ｂから端子ａに接続を切り替えるようにスイッチ手段１６を制御する。コンデンサ１７はＶ２からＶ１に電位が高くなることにより、２次電池セル１１ａから充電され、一方２次電池セル１１ａはコンデンサ１７に対して放電を行う。
バランス検出部１５がスイッチ素子１６ａ、１６ｂのスイッチング動作を繰り返すことにより、２次電池セル１１ａは放電され、電池電圧Ｖ１は低くなっていき、２次電池セル１１ｂは充電され、電池電圧Ｖ２は高くなっていく。電池電圧Ｖ１とＶ２の電圧差ΔＶが平準基準電圧Ｖｒ３より低くなるまで、スイッチング動作を続け、バランス検出部１５はスイッチング動作を停止する。
【００２４】
これにより、２次電池セル１１ａ、１１ｂの平準化を図ることができ、２次電池セル１１ａよりも電池容量の大きい２次電池セル１１ｂにも十分に充電がされ、電池容量を効率的に使用することができる。また、最も電池電圧の高い２次電池セルの電池電圧を下げながら、最も電池電圧の低い２次電池セルの電池電圧を上げることにより、各２次電池セルの電池電圧の平準化を効率よくさらに短時間で行うことができる。また、片方の電池セルのみ過電圧充電されることがなくなる。
【００２５】
次に、２次電池１１が外部に対して放電する過程について詳しく説明する。
外部端子１２に携帯型パソコン、携帯電話等の外部端子が接続されると、２次電池セル１１ａ、１１ｂは外部端子１２に対して放電電圧Ｖｄを供給する。このとき保護部１４は、スイッチ素子１８ａ、１８ｂを閉じた状態に保持させるとともに、各２次電池セル１１ａ、１１ｂの電池電圧Ｖ１、Ｖ２を測定する。また、バランス検出部１５も各２次電池セル１１ａ、１１ｂの電池電圧Ｖ１、Ｖ２を測定している。
【００２６】
２次電池セル１１ａ、１１ｂが放電している途中に、各２次電池セル１１ａ、１１ｂの電池容量の違いから電池電圧Ｖ１、Ｖ２に差異が生じた場合、バランス検出部１５がその電圧差ΔＶを測定する。電圧差ΔＶがバランス検出部１５に設定されている平準基準電圧Ｖｒ３より大きいとき、バランス検出部１５により、スイッチ手段１６のスイッチング動作が開始される。
【００２７】
ここで、放電しているときの電池電圧がＶ１＜Ｖ２の関係であるとする。このとき、バランス検出部１５はスイッチ素子１６ａ、１６ｂを端子ｂに接続させて、２次電池セル１１ｂとコンデンサ１７とを並列に接続する。これにより、コンデンサ１７には電池電圧Ｖ２と同じ電圧が印加され、コンデンサ１７には電荷が蓄えられる。このとき、２次電池セル１１ｂはコンデンサ１７に対して放電することになる。
【００２８】
次に、バランス検出部１５はスイッチ素子１６ａ、１６ｂを端子ａに接続させ、２次電池セル１１ａとコンデンサ１７とが並列に接続される。そして、２次電池セル１１ａとコンデンサ１７のそれぞれの電圧Ｖ１、Ｖ３は等しくなるが、コンデンサ１７には２次電池セル１１ａから放電された電荷が蓄えられている。このため、２次電池セル１１ａはコンデンサ１７から充電されることになる。
【００２９】
そして、バランス検出部１５は２次電池セル１１ａ、１１ｂの電池電圧の電圧差ΔＶが平準基準電圧Ｖｒ３より低くなるまで、スイッチング動作を続ける。そして、電池電圧Ｖ１とＶ２がほぼ等しくなったらバランス検出部１５はスイッチング動作を停止する。
過放電保護部１４ｂは、各２次電池セル１１ａ、１１ｂの電池電圧Ｖ１、Ｖ２を測定しており、電池電圧Ｖ１、Ｖ２が下限基準電圧Ｖｒ２より低くなったとき、スイッチ素子１８ｂを開いて放電を停止する。
【００３０】
従来、放電時において、電池電圧が低い２次電池セルの放電が終了してしまった場合、他の２次電池セルが放電可能な状態であっても、放電が停止されてしまったが、上記実施の形態によると、放電中に各２次電池セルの電池電圧が平準化されているので、各２次電池セルがほぼ同時に放電停止の状態となる。放電時においても各２次電池セルの平準化を行うことにより、効率よく２次電池セルに蓄えられた電力を放電することができる。
【００３１】
また、コンデンサ１７は電池電圧の高い２次電池セルから放電させ、電池電圧の低い２次電池セルに充電し電池電圧を上げることで、各２次電池セルの電池電圧の平準化の時間を短縮することができる。さらに、各２次電池セルの電池電圧を平準化する際に、各２次電池セルの充電動作を停止しないため、充電時間の短縮を図ることができる。
【００３２】
そして、制御装置１３が電池パック１０に組み込まれてさえいれば、通常の充電器で充電を行うことができるため、新たに充電器を買い換える必要がない。すなわち、上記実施の形態においては充電電圧自体の変更もしくは切り替え等の動作を行わずに各２次電池セルの平準化を行うことができるので、充電器側に充電電圧の変更等するための回路を組み込む必要がない。これに伴い、各２次電池セルの電圧を充電器側に送る必要がないため、電圧差測定用の外部端子を設ける必要がなくなる。
【００３３】
上記各実施の形態によれば、各２次電池セルの電池電圧の平準化が充電時または放電時のいずれの状態においても電池電圧のバランスが崩れればいつでも補正され、無駄のない充電、放電を行うことができる。従って、電池容量の異なる２次電池セルが複数直列接続されている構成であっても、その中の一番小さな電池容量が充電容量、放電容量を決定することがなく、各２次電池セルの持つ電池容量が平準化され電池パック全体の電池容量を向上させることができる。
また、充電時に各２次電池セル間の容量が異なっても、電池電圧のバランスが崩れて、過電圧充電されることがないため、２次電池セルを劣化させることがなくなる。
【００３４】
ところで、本発明は、上記実施の形態に限定されない。
上記各実施の形態において、２個の２次電池セルを有する電池パックを例にして説明しているが、３個以上の２次電池セルが直列に配置されている電池パックにおいても、２次電池の制御装置を用いることができる。
また、２次電池の制御装置１３は、電池パック１０に収容されているが、外部端子に接続される充電装置、もしくは電子機器に収容させてもよい。
【００３５】
【発明の効果】
以上説明したように、本発明によれば、２次電池を効率よく充電あるいは放電させる２次電池の制御装置及びそれを用いた電池パックを提供することを目的としている。
【図面の簡単な説明】
【図１】本発明の２次電池の制御装置を用いた電池パックの好ましい実施の形態を示す概略図。
【図２】図１のスイッチ手段１６が端子ａに接続された場合の回路図。
【図３】図１のスイッチ手段１６が端子ｂに接続された場合の回路図。
【図４】図１のスイッチ手段１６が端子ａに接続された場合の回路図。
【図５】従来の２次電池の制御装置を有する電池パックを示すシステム図。
【符号の説明】
１０・・・電池パック、１１ａ、１１ｂ・・・２次電池セル、１２・・・外部端子、１３・・・制御装置、１４・・・保護部、１５・・・バランス検出部、１６・・・スイッチ手段、１７・・・コンデンサ（蓄電部）、１８・・・スイッチ手段。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a secondary battery, a battery pack including the control device for the secondary battery, and an improvement of the control method for the secondary battery. The present invention relates to a battery pack provided with a control device for a secondary battery and a control method for a secondary battery.
[0002]
[Prior art]
Rechargeable batteries (secondary batteries) such as lithium ion batteries, nickel cadmium batteries, and nickel metal hydride batteries are used in portable personal computers, mobile phones, video cameras, and the like. A secondary battery refers to a battery that can be regenerated by supplying energy from the outside after discharging.
The secondary battery may be accommodated in a case, and a plurality of secondary batteries are connected in series in the case, for example. An external terminal is provided on the outer peripheral surface of the case, and the secondary battery is charged or discharged by connecting a charging device or an electronic device such as a mobile phone to the external terminal.
[0003]
FIG. 5 shows a system diagram of a conventional battery pack 10. The battery pack 1 of FIG. 5 includes a secondary battery 2, a protection unit 3, a switch means 4, a resistor 5, an external terminal 6, and the like.
The secondary battery 2 includes, for example, two secondary battery cells 2a and 2b, and the secondary battery cells 2a and 2b are arranged in series. An external terminal 6 is connected to the secondary battery cells 2a and 2b, and a protection unit 3 is connected between the secondary battery cells 2a and 2b via a resistor 5. The switch means 4 includes switch elements 4a and 4b, and is connected in parallel to the secondary battery cells 2a and 2b, respectively. The switch means 8 is composed of switch elements 8a and 8b. The switch means 8 is provided between the external terminal 6 and the secondary battery cells 2 a and 2 b, and the switching operation is controlled by the protection unit 3. The protection unit 3 includes an overcharge protection unit 3a and an overdischarge protection unit 3b, so that the secondary battery cells 2a and 2b are not excessively charged or discharged.
[0004]
The battery pack 1 is charged by applying a charging voltage Vc to the external terminal 6 and supplying the charging voltage Vc to the secondary battery cells 2a and 2b. At this time, the overcharge protection unit 3a measures the battery voltages V1 and V2 of the secondary battery cells 2a and 2b, respectively. When the overcharge protection unit 3a determines that the charging of the secondary battery cells 2a and 2b is completed, the overcharge protection unit 3a opens the switch element 8a to charge the secondary battery cells 2a and 2b with a charging voltage. Vc supply is stopped.
[0005]
In order to determine that charging of the secondary battery cells 2a, 2b has been completed, the overcharge protection unit 3a is set to stop charging when the secondary battery cells 2a, 2b reach the reference voltage Vr. Yes. When the battery capacities of the secondary battery cells 2a and 2b are different (2a> 2b), the secondary battery cell 2b having a small battery capacity finishes charging earlier. For this reason, when the battery voltage V2 of the secondary battery cell 2b reaches the reference voltage Tr of the overcharge protection unit 3a, the charging is terminated, and the secondary battery cell 2a is not fully charged. Therefore, it is necessary to discharge the battery voltage of the secondary battery cell at the time of charging and to equalize each battery voltage.
[0006]
Therefore, when the secondary battery cell 2a exceeds the reference voltage Vr of the overcharge protection unit 3a, the overcharge protection unit 3a closes the switch element 4a. Thereby, the battery voltage of the secondary battery cell 2b is discharged to the reference voltage Vr or less by the resistor 5, and the battery voltages V1 and V2 of the secondary battery cell 2a and the secondary battery cell 2b are leveled. Thereafter, the switch element 4a is opened and charging is resumed.
[0007]
[Problems to be solved by the invention]
However, conventionally, the overcharge protection unit 3a does not operate the overcharge protection function unless the battery voltages V1 and V2 reach the reference voltage Vr. That is, when the battery voltage V2 of the secondary battery cell 2b reaches the reference voltage Vr of the overcharge protection unit 3a during charging, the charging ends, and the secondary battery cell 2a cannot be charged sufficiently. There is a problem that the battery capacity of the secondary battery cell 2a cannot be used efficiently.
[0008]
In addition, when there is a difference in the battery capacity of the secondary battery cells 2a and 2b at the time of discharge, the discharge ends when the battery voltage of the cell having the smallest battery capacity reaches the reference voltage Vr of the overdischarge protection unit 3b. It was. That is, some of the conventional batteries have a function of leveling the secondary battery cells 2a and 2b at the time of charging, but the function of leveling the secondary battery cells 2a and 2b when the secondary battery cells are discharged. There was nothing to have. Accordingly, there is a problem that the battery voltage charged in the secondary battery cell having a large battery capacity cannot be completely used up and the discharge efficiency is poor.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems and provide a secondary battery control device that efficiently charges or discharges a secondary battery and a battery pack using the same.
[0010]
[Means for achieving the object]
In order to achieve the above-described object, the present invention supplies a plurality of secondary battery cells connected in series and a charge voltage to each secondary battery cell, or a discharge voltage is supplied from each secondary battery cell. In a secondary battery control device having an external terminal and a protection unit that controls a charge voltage supplied from the external terminal and a discharge voltage supplied to the external terminal, a plurality of secondary battery cells connected in parallel to each secondary battery cell Provided between the switch element and the switch means, the balance detection unit for measuring the battery voltage of each secondary battery cell and controlling the switching operation of the switch means based on the measured value. and, by the switching operation of each switch element, have a power storage unit that is connected in parallel with each secondary battery cell, the above-mentioned balance detection unit, leveling reference voltage value is set Among the plurality of secondary battery cells, the secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage are detected, and the potential difference and leveling between the secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage are detected. When the reference voltage value is compared and the potential difference is larger than the level reference voltage value, the power storage unit is connected to the secondary battery cell having the highest battery voltage, and the power storage unit is charged.
Switch the connection of the power storage unit from the secondary battery cell with the highest battery voltage to the secondary battery cell with the lowest battery voltage, and charge the secondary battery cell with the lowest battery voltage from the power storage unit. The connection of the power storage unit is repeatedly switched until it becomes smaller than the voltage value .
[0011]
In this invention, a balance detection part measures the battery voltage of each secondary battery, and calculates the voltage difference of each secondary battery. Based on the value of the voltage difference, the balance detection means controls the switching operation of the switch means. By the operation of the switch means, the power storage unit is connected in parallel with each secondary battery cell, and each secondary battery cell discharges or charges the battery voltage to the storage battery. Thereby, the battery voltage of each secondary battery cell is leveled.
As a result, when the secondary battery is charged or discharged, the battery voltage of each secondary battery cell can be kept substantially the same, so that charging or discharging can be performed efficiently. Further, the leveling of the secondary battery can be performed efficiently.
[0012]
In addition, the present invention provides a secondary battery control method for supplying a charging voltage to a plurality of secondary battery cells connected in series or discharging the electric power stored in each secondary battery cell to the outside. , The secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage among the plurality of secondary battery cells are detected, and the potential difference between the secondary battery cell having the highest battery voltage and the lowest secondary battery cell. If the potential difference is larger than the level reference voltage value, the power storage unit is connected to the secondary battery cell having the highest battery voltage, and the power storage unit is charged. Switch the connection of the power storage unit from the secondary battery cell to the secondary battery cell with the lowest battery voltage, and charge the secondary battery cell with the lowest battery voltage from the power storage unit until the potential difference becomes smaller than the level reference voltage value Switch the connection of the power storage unit It is that to return Ri.
[0013]
In this invention, it charges with respect to the secondary battery cell with the lowest battery voltage from the secondary battery cell with the highest battery voltage using an electrical storage part. As a result, when the secondary battery is charged or discharged, the battery voltage of each secondary battery cell can be kept substantially the same, so that charging or discharging can be performed efficiently. Further, the leveling of the secondary battery can be performed efficiently.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.
[0015]
FIG. 1 shows a conceptual diagram of an embodiment of a battery pack provided with a control device for a secondary battery of the present invention. The battery pack 10 will be described in detail with reference to FIG. The battery pack 10 in FIG. 1 includes a secondary battery 11, an external terminal 12, a control device 13, and the like.
The secondary battery 11 includes, for example, two secondary battery cells 11a and 11b, and the secondary battery cells 11a and 11b are arranged in series. The secondary battery cells 11 a and 11 b are made of, for example, a lithium ion battery, a nickel cadmium battery, a nickel hydrogen battery, or the like, and the secondary battery 11 is connected to the external terminal 12.
When a charging device is connected to the external terminal 12, the charging voltage Vc is supplied to the secondary battery cells 11a and 11b, and when an electronic device or the like is connected to the external terminal 12, the secondary battery cells 11a and 11b are electronic devices. Is supplied with a discharge voltage Vd.
[0016]
A control device 13 is disposed between the secondary battery cells 11 a and 11 b and the external terminal 12. The control device 13 includes a protection unit 14, a balance detection unit 15, a switch unit 16, a capacitor 17 that is a power storage unit, and the like.
The protection unit 14 includes an overcharge protection unit 14a and an overdischarge protection unit 14b. The overcharge protection unit 14a is connected to the switch element 18a and controls its switching operation. Moreover, the overdischarge protection part 14b is connected to the switch element 18b, and controls the switching operation. An upper limit reference voltage Vr1 is set for the overcharge protection unit 14a, and a lower limit reference voltage Vr2 is set for the overdischarge protection unit 14b.
When the battery voltages V1 and V2 become higher than the upper limit reference voltage Vr1, the overcharge protection unit 14a opens the switch element 18a and stops charging in order to end the charging. Further, when the battery voltages V1 and V2 become lower than the lower limit reference voltage Vr2, the overdischarge protection unit 14b opens the switch element 18b and stops discharging.
[0017]
Next, the balance detection unit 15 will be described in detail.
The balance detection unit 15 is connected to both ends of the secondary battery cells 11a and 11b. Moreover, the balance detection part 15 is connected with the switch means 16 mentioned later, and controls the switching operation | movement. Further, a level reference voltage Vr3 is set in the balance detection unit 15.
The balance detection unit 15 measures the battery voltages V1 and V2 of the secondary battery cells 11a and 11b, and detects the voltage difference ΔV. Then, the potential difference ΔV and the level reference voltage Vr3 are compared, and the switching of the switch means 16 is controlled according to the result.
[0018]
Switch means 16 is connected in parallel to both ends of the balance detector 15. The switch means 16 is composed of a plurality of switch elements 16a and 16b, and includes, for example, an electromagnetic relay, a field effect transistor (FET), and a photo MOS relay. The switch elements 16a and 16b are connected to both ends of the secondary battery cells 11a and 11b, respectively. A capacitor 17 is provided between the switch elements 16a and 16b. The capacitor 17 includes a ceramic capacitor, a film capacitor, an electrolytic capacitor, an electric double layer capacitor, and the like. Further, a secondary battery may be used instead of the capacitor 17.
When switch elements 16a and 16b are connected to terminal a, capacitor 17 is connected in parallel with secondary battery cell 11a, and when connected to terminal b, capacitor 17 is connected in parallel with secondary battery cell 11b. .
[0019]
Next, a process of charging the secondary battery cells 11a and 11b will be described in detail with reference to FIGS.
The charging voltage Vc is supplied from the outside to the external terminal 12, and the charging voltage Vc is applied to the secondary battery cells 11a and 11b. At this time, the protection unit 14 keeps the switch means 18 closed. The battery voltages V1 and V2 of the secondary battery cells 11a and 11b are measured by the balance detection unit 15. When charging of the secondary battery cells 11a and 11b is completed, the overcharge protection unit 14a opens the switch element 18a and stops charging. It is possible to prevent the secondary battery cells 11a and 11b from being excessively charged or discharged, and to prevent a decrease in discharge capacity and an internal short circuit due to deterioration of the secondary battery cells 11a and 11b.
[0020]
Here, when the battery capacities C1 and C2 of the secondary battery cells 11a and 11b are different (C1 <C2), the battery voltage V1 of the secondary battery cell 11a is higher than the battery voltage V2 of the secondary battery cell 11b. Become. And the balance detection part 15 compares this battery voltage V1, V2, and measures the voltage difference (DELTA) V. Then, the balance detector 15 compares the voltage difference ΔV with the level reference voltage Vr3. When the voltage difference ΔV is smaller than the level reference voltage Vr3 (ΔV <Vr3), the balance detection unit 15 does not operate the switch means 16 and maintains a state where it is not connected to any of the terminals a and b. Thereby, the normal charging voltage Vc is supplied to the secondary battery cells 11a and 11b, and charging is performed.
[0021]
On the other hand, when the potential difference ΔV becomes larger than the level reference voltage Vr3 (ΔV> Vr3), the balance detection unit 15 connects the switch elements 16a and 16b to the terminal a, and as shown in FIG. The secondary battery cell 11a is connected in parallel. Then, the voltage V3 of the capacitor 17 becomes the same as the battery voltage V1 (V3 = V1), and the charge Q is stored in the capacitor 17. At this time, the secondary battery secondary battery cell 11a is discharged to the capacitor 17. Thereby, the battery voltage V1 of the secondary battery cell 11a can be lowered.
[0022]
Next, when V3 = V1, the balance detection unit 15 connects the switch elements 16a and 16b to the terminal b. Then, as shown in FIG. 3, the capacitor 17 is connected to the secondary battery cell 11b in parallel. The voltage V3 of the capacitor 17 becomes the same as the battery voltage V2 (V3 = V2). At this time, since the voltage V3 of the capacitor 17 decreases from the voltage V1 to V2, the secondary battery cell 11b is charged by the capacitor 17. Thereby, the battery voltage V2 of the secondary battery cell 11b can be raised.
[0023]
And the balance detection part 15 controls the switch means 16 so that a connection may be switched from the terminal b to the terminal a, as shown in FIG. The capacitor 17 is charged from the secondary battery cell 11 a by increasing the potential from V 2 to V 1, while the secondary battery cell 11 a discharges the capacitor 17.
When the balance detection unit 15 repeats the switching operation of the switch elements 16a and 16b, the secondary battery cell 11a is discharged, the battery voltage V1 decreases, the secondary battery cell 11b is charged, and the battery voltage V2 increases. It will become. The switching operation is continued until the voltage difference ΔV between the battery voltages V1 and V2 becomes lower than the level reference voltage Vr3, and the balance detection unit 15 stops the switching operation.
[0024]
As a result, the secondary battery cells 11a and 11b can be leveled, and the secondary battery cell 11b having a larger battery capacity than the secondary battery cell 11a can be sufficiently charged to efficiently use the battery capacity. can do. In addition, by lowering the battery voltage of the secondary battery cell having the highest battery voltage while increasing the battery voltage of the secondary battery cell having the lowest battery voltage, the battery voltage of each secondary battery cell can be leveled more efficiently. It can be done in a short time. In addition, overvoltage charging is not performed on only one battery cell.
[0025]
Next, the process of discharging the secondary battery 11 to the outside will be described in detail.
When an external terminal such as a portable personal computer or a mobile phone is connected to the external terminal 12, the secondary battery cells 11 a and 11 b supply a discharge voltage Vd to the external terminal 12. At this time, the protection unit 14 keeps the switch elements 18a and 18b closed, and measures the battery voltages V1 and V2 of the secondary battery cells 11a and 11b. Further, the balance detection unit 15 also measures the battery voltages V1 and V2 of the secondary battery cells 11a and 11b.
[0026]
In the middle of discharging the secondary battery cells 11a and 11b, when a difference occurs in the battery voltages V1 and V2 due to the difference in battery capacity between the secondary battery cells 11a and 11b, the balance detection unit 15 detects the voltage difference ΔV. Measure. When the voltage difference ΔV is larger than the level reference voltage Vr3 set in the balance detector 15, the balance detector 15 starts the switching operation of the switch means 16.
[0027]
Here, it is assumed that the battery voltage when discharging is in a relationship of V1 <V2. At this time, the balance detection unit 15 connects the switch elements 16a and 16b to the terminal b, and connects the secondary battery cell 11b and the capacitor 17 in parallel. As a result, the same voltage as the battery voltage V <b> 2 is applied to the capacitor 17, and charges are stored in the capacitor 17. At this time, the secondary battery cell 11 b is discharged to the capacitor 17.
[0028]
Next, the balance detection unit 15 connects the switch elements 16a and 16b to the terminal a, and the secondary battery cell 11a and the capacitor 17 are connected in parallel. The voltages V1 and V3 of the secondary battery cell 11a and the capacitor 17 are equal, but the capacitor 17 stores the electric charge discharged from the secondary battery cell 11a. For this reason, the secondary battery cell 11 a is charged from the capacitor 17.
[0029]
Then, the balance detection unit 15 continues the switching operation until the voltage difference ΔV between the battery voltages of the secondary battery cells 11a and 11b becomes lower than the level reference voltage Vr3. And if battery voltage V1 and V2 become substantially equal, the balance detection part 15 will stop switching operation | movement.
The overdischarge protection unit 14b measures the battery voltages V1 and V2 of the respective secondary battery cells 11a and 11b. When the battery voltages V1 and V2 become lower than the lower limit reference voltage Vr2, the switch element 18b is opened to discharge. To stop.
[0030]
Conventionally, when the discharge of the secondary battery cell having a low battery voltage has been completed at the time of discharging, the discharge has been stopped even if the other secondary battery cell is in a dischargeable state. According to the embodiment, since the battery voltage of each secondary battery cell is leveled during discharge, each secondary battery cell is in a state of stopping discharge almost simultaneously. Even during discharging, the power stored in the secondary battery cells can be discharged efficiently by leveling each secondary battery cell.
[0031]
In addition, the capacitor 17 is discharged from a secondary battery cell having a high battery voltage, and charged to a secondary battery cell having a low battery voltage to increase the battery voltage, thereby shortening the time for equalizing the battery voltage of each secondary battery cell. can do. Furthermore, when the battery voltage of each secondary battery cell is leveled, the charging operation of each secondary battery cell is not stopped, so that the charging time can be shortened.
[0032]
As long as the control device 13 is incorporated in the battery pack 10, charging can be performed with a normal charger, so that it is not necessary to purchase a new charger. That is, in the above-described embodiment, since the secondary battery cells can be leveled without performing the operation of changing or switching the charging voltage itself, a circuit for changing the charging voltage on the charger side. Need not be included. Along with this, it is not necessary to send the voltage of each secondary battery cell to the charger side, so there is no need to provide an external terminal for voltage difference measurement.
[0033]
According to each of the above embodiments, the leveling of the battery voltage of each secondary battery cell is corrected whenever the battery voltage is unbalanced in any state during charging or discharging, and charging and discharging without waste It can be performed. Accordingly, even when a plurality of secondary battery cells having different battery capacities are connected in series, the smallest battery capacity among them does not determine the charge capacity and discharge capacity, and each secondary battery cell The battery capacity possessed is leveled, and the battery capacity of the entire battery pack can be improved.
Further, even if the capacity between the secondary battery cells is different during charging, the battery voltage is not balanced and overvoltage charging is not performed, so that the secondary battery cell is not deteriorated.
[0034]
By the way, the present invention is not limited to the above embodiment.
In each of the above embodiments, a battery pack having two secondary battery cells has been described as an example. However, even in a battery pack in which three or more secondary battery cells are arranged in series, A battery control device can be used.
Moreover, although the control apparatus 13 of the secondary battery is accommodated in the battery pack 10, you may make it accommodate in the charging device connected to an external terminal, or an electronic device.
[0035]
【The invention's effect】
As described above, it is an object of the present invention to provide a secondary battery control device that efficiently charges or discharges a secondary battery and a battery pack using the same.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a preferred embodiment of a battery pack using a control apparatus for a secondary battery of the present invention.
FIG. 2 is a circuit diagram when the switch means 16 of FIG. 1 is connected to a terminal a.
FIG. 3 is a circuit diagram when the switch means 16 of FIG. 1 is connected to a terminal b.
4 is a circuit diagram when the switch means 16 of FIG. 1 is connected to a terminal a.
FIG. 5 is a system diagram showing a battery pack having a conventional secondary battery control device;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Battery pack, 11a, 11b ... Secondary battery cell, 12 ... External terminal, 13 ... Control apparatus, 14 ... Protection part, 15 ... Balance detection part, 16 ... Switch means, 17 ... capacitor (power storage unit), 18 ... switch means.

Claims

A plurality of secondary battery cells connected in series, a charging voltage supplied to each secondary battery cell, or an external terminal to which a discharge voltage is supplied from each secondary battery cell, and a charging voltage supplied from the external terminal And a control device for a secondary battery having a protection unit for controlling a discharge voltage supplied to the external terminal,
Switch means comprising a plurality of switch elements connected in parallel to each secondary battery cell;
A balance detector that measures the battery voltage of each secondary battery cell and controls the switching operation of the switch means based on the measured value;
Is provided between the switching element and the switching element, the switching operation of each switching element, have a power storage unit that is connected in parallel with each secondary battery cell,
In the balance detection unit, a level reference voltage value is set. Among the plurality of secondary battery cells, the secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage are detected, and the battery voltage is detected. Compare the potential difference between the highest secondary battery cell and the lowest secondary battery cell with the level reference voltage value. If the potential difference is greater than the level reference voltage value, connect the battery unit to the secondary battery cell with the highest battery voltage. To charge the battery,
Switch the connection of the power storage unit from the secondary battery cell with the highest battery voltage to the secondary battery cell with the lowest battery voltage, and charge the secondary battery cell with the lowest battery voltage from the power storage unit. A control device for a secondary battery, wherein the switching of the connection of the power storage unit is repeated until the voltage value becomes smaller .

A plurality of secondary battery cells connected in series, a charging voltage supplied to each secondary battery cell, or an external terminal to which a discharge voltage is supplied from each secondary battery cell, and a charging voltage supplied from the external terminal And a battery pack comprising a secondary battery control device having a protection unit for controlling a discharge voltage supplied to the external terminal,
Switch means comprising a plurality of switch elements connected in parallel to each secondary battery cell;
Balance detecting unit for measuring a battery voltage of each secondary battery cell and controls the switching operation of the switching means,
A power storage unit provided between the switch elements and connected to each secondary battery cell in parallel by a switching operation of each switch element;
In the balance detection unit, a level reference voltage value is set. Among the plurality of secondary battery cells, the secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage are detected, and the battery voltage is detected. Compare the potential difference between the highest secondary battery cell and the lowest secondary battery cell with the level reference voltage value. If the potential difference is greater than the level reference voltage value, connect the battery unit to the secondary battery cell with the highest battery voltage. To discharge the power storage unit,
Switch the connection of the power storage unit from the secondary battery cell with the highest battery voltage to the secondary battery cell with the lowest battery voltage, and charge the secondary battery cell with the lowest battery voltage from the power storage unit. A battery pack provided with a control device for a secondary battery, wherein the connection of the power storage unit is repeatedly switched until the voltage value becomes smaller .

In a secondary battery control method for supplying a charging voltage to a plurality of secondary battery cells connected in series or discharging the power stored in each secondary battery cell to the outside,
Among the plurality of secondary battery cells, the secondary battery cell having the highest battery voltage and the secondary battery cell having the lowest battery voltage are detected,
Compare the potential difference between the secondary battery cell with the highest battery voltage and the secondary battery cell with the lowest battery voltage and the level reference voltage value,
When the potential difference is larger than the level reference voltage value, the power storage unit is connected to the secondary battery cell having the highest battery voltage, and the power storage unit is charged.
Switch the connection of the power storage unit from the secondary battery cell with the highest battery voltage to the secondary battery cell with the lowest battery voltage, and charge the secondary battery cell with the lowest battery voltage from the power storage unit,
A method for controlling a secondary battery, characterized by repeatedly switching the connection of power storage units until the potential difference becomes smaller than a level reference voltage value.