JP4108339B2 - Lithium ion secondary battery charging method and apparatus - Google Patents

Lithium ion secondary battery charging method and apparatus Download PDF

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JP4108339B2
JP4108339B2 JP2002014401A JP2002014401A JP4108339B2 JP 4108339 B2 JP4108339 B2 JP 4108339B2 JP 2002014401 A JP2002014401 A JP 2002014401A JP 2002014401 A JP2002014401 A JP 2002014401A JP 4108339 B2 JP4108339 B2 JP 4108339B2
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ion secondary
lithium ion
charging
secondary battery
battery
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JP2003217675A (en
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晋也 高木
敏雄 松島
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NTT Facilities Inc
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Description

【０００１】
【発明の属する技術分野】
本発明は、複数個のリチウムイオン二次電池が直列状態に接続された組電池において各単電池の充電をバランス良く実行させるリチウムイオン二次電池の充電方法及び装置に関する。
【０００２】
【従来の技術】
一般に携帯電話機やコードレス電話機などの移動無線通信機をはじめ、ビデオカメラやノート型パソコンなどでは、体積エネルギー密度および重量エネルギー密度が高いリチウムイオン二次電池が多く使われている。このリチウムイオン二次電池は、通常、単セル（単電池）を複数個、直列接続して上記の電子機器の電源として使用される。
【０００３】
従来、リチウムイオン二次電他の充電は、単セル当たり４．１Ｖまたは４．２Ｖという一定値に充電電圧を設定し、電池電圧がこれらの充電完了電圧に到達するまでは一定電流値で充電し、充電完了電圧に達した以後は、定電圧充電に移行する定電流・定電圧充電方式が採用されている。
一方、直列接続されたリチウムイオン二次電池の充電は、例えば単セル当たりの充電完了電圧を４．１Ｖとするとセルがｎ個、直列接続された組電池はｎ×４．１Ｖになるまで定電流充電をすることになる（図３参照）。
【０００４】
しかし、上述した定電流・定電圧充電方式では、各セルの端子電圧を個別に監視していないので、充電時に各セルの端子電圧にばらつきがあると、任意のセルが充電完了電圧に達しても他の電池が充電完了電圧に達していないために充電が継続して行われ、一番初めに充電完了電圧に到達したセルは過充電になってしまう。
【０００５】
【発明が解決しようとする課題】
直列接続された複数個のリチウムイオン二次電池をトリクル充電方式で使用する場合、全ての電池の容量あるいは内部抵抗が常に同じであればバランス良く充電できる。
しかしながら、実際には、電池の容量あるいは内部抵抗には若干のばらつきが存在する。更に、初期において同じ内部抵抗であったとしてもトリクル充電により、時間が経過していくと電池の内部特性が変化し、電池の容量および内部抵抗も変化する。その結果、各電池のバランスが崩れ、特定の電池が過充電状態になることもある。
【０００６】
一方、他の電池は満充電に達しない状態で充電が終わってしまうので、電池の保有している能力を十分に取り出すことができなくなる。このように従来の充電方式では、各電池を確実に満充電状態まで充電することができない場合がある。
本発明はこのような事情に鑑みてなされたものであり、直列接続された複数個のリチウムイオン二次電池についてトリクル充電方式で待機している組電池の充電を、安価かつ効率的に行うことを可能とするリチウムイオン二次電池の充電装置を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載の発明は、直流負荷に電力を供給する直流電源の出力に、前記直流負荷と並列に、複数のリチウムイオン二次電池が直列接続されてなる組電池が接続されて使用される前記各リチウムイオン二次電池の充電を行うリチウムイオン二次電池の充電方法であって、前記組電池を構成する各リチウムイオン二次電池を充電し、かつ前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出すると共に、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡して充電電流をバイパスし、前記組電池を構成する全てのリチウムイオン二次電池が充電完了電圧に達した後に前記組電池を構成する各リチウムイオン二次電池に対してトリクル充電を行うことを特徴とする。
【０００８】
請求項２に記載の発明は、直流負荷に電力を供給する直流電源の出力に、前記直流負荷と並列に、複数のリチウムイオン二次電池が直列接続されてなる組電池が接続されて使用される前記各リチウムイオン二次電池の充電を行うリチウムイオン二次電池の充電装置であって、前記組電池の端子間に接続され前記組電池を構成する各リチウムイオン二次電池を充電する充電手段と、前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出する電圧検出手段と、前記組電池を構成する各リチウムイオン二次電池の端子間に接続され、入力される制御信号に基づいて該接続されたリチウムイオン二次電池の端子間を短絡するバイパス手段と、前記電圧検出手段の検出出力を取り込み、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡するように前記バイパス手段を制御する制御手段と、前記組電池の正極性端子側と、直流負荷及び直流電源との間に、該直流負荷及び直流電源に対して前記組電池を構成する各リチウムイオン二次電池の放電を許容する極性となるように接続されるダイオードとを有することを特徴とする。
【０００９】
請求項３に記載の発明は、請求項１に記載のリチウムイオン二次電池の充電装置において、前記制御手段は、前記組電池を構成する全てのリチウムイオン二次電池が充電完了電圧に達した後に前記バイパス手段を非動作状態にすることを特徴とする。
【００１０】
【発明の実施の形態】
以下、本発明の実施形態を、図面を参照して詳細に説明する。本発明の実施形態に係るリチウムイオン二次電池の充電装置の構成を図１に示す。本実施形態に係るリチウムイオン二次電池の充電装置は、直流負荷に電力を供給する直流電源の出力に、前記直流負荷と並列に、複数のリチウムイオン二次電池が直列接続されてなる組電池が接続されて使用される前記各リチウムイオン二次電池の充電を行うリチウムイオン二次電池の充電方法であって、前記組電池を構成する各リチウムイオン二次電池を充電し、かつ前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出すると共に、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡して充電電流をバイパスし、前記組電池を構成する全てのリチウムイオン二次電池が充電完了電圧に達した後に前記組電池を構成する各リチウムイオン二次電池に対してトリクル充電を行うことを特徴とするリチウムイオン二次電池の充電方法を実施するための装置である。
【００１１】
図１において、本実施形態に係るリチウムイオン二次電池の充電装置は、直流負荷２に電力を供給する直流電源３の出力に、直流負荷２と並列に、複数のリチウムイオン二次電池（セル）１−１、１−２、１−３、…、１−ｎが直列接続されてなる組電池が接続されて使用される各リチウムイオン二次電池の充電を行うリチウムイオン二次電池の充電装置である。
【００１２】
本実施形態に係るリチウムイオン二次電池の充電装置は、上記組電池の端子間に接続され上記組電池を構成する各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎを充電するリチウムイオン二次電池専用充電器（以下、単に充電器と記す。）５と、各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎの端子間電圧を検出する電圧プローブ６−１、６−２、６−３、…、６−ｎと、各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎの端子間に接続され、入力される制御信号に基づいて該接続されたリチウムイオン二次電池の端子間を短絡するバイパス回路４−１、４−２、４−３、…、４−ｎと、電圧プローブ６−１、６−２、６−３、…、６−ｎの検出出力を取り込み、各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎのうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡するようにバイパス回路４−１、４−２、４−３、…、４−ｎを制御する制御部７と、上記組電池の正極性端子側と、直流負荷２及び直流電源３との間に、該直流負荷２及び直流電源３に対して上記組電池を構成する各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎの放電を許容する極性となるように接続されるダイオード１０とを有している。
【００１３】
また、各バイパス回路４−１、４−２、４−３、…、４−ｎは、各リチウムイオン二次電池の両端間に接続される第１のＩＧＢＴ（Insulated Gate Bipolar Transistor）と第２のＩＧＢＴとの直列回路と、第１のＩＧＢＴのエミッタ−コレクタ間に図１に示す極性で接続されるダイオードとから構成されている。例えば、バイパス回路４−１は、ＩＧＢＴ：Ｐ１とＩＧＢＴ：Ｑ１の直列回路と、ＩＧＢＴ：Ｐ１のエミッタ−コレクタ間に接続されるダイオードＤ１とからなる。
ここで、リチウムイオン二次電池１−１の正極にはＩＧＢＴ：Ｐ１のコレクタが接続され、ＩＧＢＴ：Ｐ１のエミッタはＩＧＢＴ：Ｑ１のコレクタに、ＩＧＢＴ：Ｑ１のエミッタはリチウムイオン二次電池１−１の負極に、それぞれ接続されている。
【００１４】
直流電源３は交流の商用電力（図では省略）を直流電力に変換して直流負荷２に供給している。
一方、停電時に無瞬断で直流負荷２に電力を供給できるように直列接続された複数個のリチウムイオン二次電池１−１、１−２、１−３、…、１−ｎからなる組電池が、バイパス回路４−１、４−２、４−３、…、４−ｎ、ダイオード１０を介して直流負荷２の両端間に接続されている。
【００１５】
また、各セル（リチウムイオン二次電池）の端子電圧を検出する電圧プローブ６−１、６−２、６−３、…、６−ｎが制御部７に接続されている。
さらに、制御部７はバイパス回路４−１、４−２、４−３、…、４−ｎに対して充電電流のバイパスの実行、または停止を指示する制御信号を供給するためのＩＧＢＴ制御線８−１、８−２、８−３、…、８−ｎを介してバイパス回路４−１、４−２、４−３、…、４−ｎに接続されており、制御部７は充電制御を行うための制御信号を出力する充電制御線９を介して充電器５に接続されている。
【００１６】
制御部７は、電圧プローブ６−１、６−２、６−３、…、６−ｎの検出出力を取り込み、各リチウムイオン二次電池のいずれかの電池電圧、すなわち端子間電圧が予め設定した状態を検出すると、該検出されたリチウムイオン二次電池に対応するＩＧＢＴ制御線８−１、８−２、８−３、…、８−ｎのいずれかを介して充電電流をバイパスさせるための制御信号を出力し、該当するバイパス回路４（４−１、４−２、４−３、…、４−ｎのいずれか）のＩＧＢＴを動作させ充電完了電圧に達したに対する充電電流をバイパスさせる機能を有している。
【００１７】
次に、上記構成からなる本発明の実施形態に係るリチウムイオン二次電池の充電装置の動作を図２及び図５を参照して説明する。
放電が終了した組電池の充電は、制御部７の制御下にバイパス回路４−１、４−２、４−３、…、４−ｎにおけるすべてのＩＧＢＴをＯＦＦした状態で充電器５により行われる。充電は、定電流−定電圧制御で行われ、単セル当たりの充電完了電圧を４．１Ｖとすると単セル（リチウムイオン二次電池）がｎ個直列接続された組電池の充電完了電圧はｎ×４．１Ｖであり、この電圧まで定電流で充電を行うことになる。
【００１８】
充電を行った際に、各リチウムイオン二次電池（セル）１−１、１−２、１−３、…、１−ｎの端子電圧が同じ充電時間で４．１Ｖになるのが理想だが、実際には、各電池の内部特性か容量にアンバランスが生じるため、例えば図４に示すように従来の充電方法ではセル１−ｎの充電電圧Ｖ1-nだけが時刻ｔ0において充電完了電圧の４．１Ｖになり、他のセルは充電完了電圧に到達しない。このように、セル１−ｎが充電完了電圧に達した後にも継続して充電すると、既に充電完了電圧に達したセル１−ｎが過充電となり危険である。
【００１９】
本発明では、制御部７は、電圧プローブ６−１、６−２、６−３、…、６−ｎの検出出力を取り込み、各リチウムイオン二次電池のいずれかの電池電圧、すなわち端子間電圧が予め設定した充電完了電圧に達した場合には、該端子間電圧が充電完了電圧に達したリチウムイオン二次電池に対応するＩＧＢＴ制御線８−１、８−２、８−３、…、８−ｎのいずれかを介して充電電流をバイパスさせるための制御信号を上記充電完了電圧に達したリチウムイオン二次電池に対応するバイパス回路に出力する。
【００２０】
例えば、制御部７により図２に示すような順番で各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎに付加したＩＧＢＴ：Ｐ１,Ｐ２,Ｐ３,…，Ｐｎ，Ｑ１，Ｑ２，Ｑ３，…，Ｑｎを制御して充電完了電圧に達したリチウムイオン二次電池の端子間に設けられたバイパス回路４（４−１、４−２、４−３、…、４−ｎのいずれか）に充電電流をバイパスさせることにより図５に示すように、既に充電完了電圧に達したリチウムイオン二次電池の過充電を防止し、各リチウムイオン二次電池の充電電圧を均一化することができる。
【００２１】
図５の例で説明すると時刻ｔ0で制御部７は、最初に充電完了電圧に到達したセル１−ｎの端子間に設けられたバイパス回路４−ｎにおけるＩＧＢＴ：ＱｎをＯＮにして充電電流をバイパスさせる。この動作を充電完了電圧に到達したセルから順番に行い、全セルについて完了するまで継続して行う。各セルが充電完了電圧に達した後は、バイパス回路４−１、４−２、４−３、…、４−ｎにおけるすべてのＩＧＢＴをＱＦＦにし、制御部７から充電制御線９を介して制御信号を受けた充電器５は、直ちに組電池トリクル充電に移行することにより、全セルを満充電状態で非常時の電池放電に備えることができる。
【００２２】
また、本発明の実施形態では、ダイオード１０がリチウムイオン二次電池１−１、１−２、１−３、…、１−ｎからなる組電池の正極性端子側と、直流負荷２及び直流電源３との間に直流負荷２及び直流電源３に対して各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎの放電を許容する極性となるように接続されているので、直流電源３からの充電を防止した上で、各リチウムイオン二次電池１−１、１−２、１−３、…、１−ｎに対して充電器５により充電を行うことができる。
なお、電池の充電中に、直流負荷２の消費電力に増加があった場合にはリチウムイオン二次電池１−１、１−２、１−３、…、１−ｎからなる組電池もしくは充電器５から直流負荷２に対して電力供給を行うこともできる。
【００２３】
本発明の実施形態に係るリチウムイオン二次電池の充電装置によれば、直列接続された複数個の各リチウムイオン二次電池（セル）の電池電圧を検出し、いずれか一つのセルが充電完了電圧に到達するまで充電し、いずれか一つのセルが充電完了電圧に到連した後は、充電完了したセルに対応して設けられたバイパス回路を構成するＩＧＢＴを制御して充電電流をバイパスし、その他のセルが充電完了電圧に到達するまで順番に一セルずつ充電していくことにより、セル間の端子電圧のアンバランスを容易に解消できる。
【００２４】
【発明の効果】
以上、説明したように、本発明によれば、前記組電池を構成する各リチウムイオン二次電池を充電し、かつ前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出すると共に、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡して充電電流をバイパスし、前記組電池を構成する全てのリチウムイオン二次電池が充電完了電圧に達した後に前記組電池を構成する各リチウムイオン二次電池に対してトリクル充電を行うようにしたので、直列接続された複数個のリチウムイオン二次電池についてトリクル充電方式で待機している組電池の充電を、安価かつ効率的に行うことを可能となる。
【図面の簡単な説明】
【図１】 本発明の実施形態に係るリチウムイオン二次電池の充電装置の構成を示すブロック図。
【図２】 図１に示した本発明の実施形態に係るリチウムイオン二次電池の充電装置におけるバイパス回路を構成するＩＧＢＴの開閉タイミングを示す説明図。
【図３】 従来のリチウムイオン二次電池の組電池充電時の電圧、電流特性を示す説明図。
【図４】 従来のリチウムイオン二次電池の単電池充電時の電圧、電流特性を示す説明図。
【図５】 本発明の実施形態に係るリチウムイオン二次電池の充電装置におけるリチウムイオン二次電池の単電池充電時の電圧、電流特性を示す説明図。
【符号の説明】
１−１、１−２、１−３、…、１−ｎ…リチウムイオン二次電池
２…直流負荷
３…直流電源
４−１、４−２、４−３、…、４−ｎ…バイパス回路
５…リチウムイオン二次電池専用充電器
６−１、６−２、６−３、…、６−ｎ…電圧プローブ
７…制御部
８−１、８−２、８−３、…、８−ｎ…ＩＧＢＴ制御線
９…充電制御線
１０…ダイオード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for charging a lithium ion secondary battery in which charging of each cell is performed in a balanced manner in an assembled battery in which a plurality of lithium ion secondary batteries are connected in series.
[0002]
[Prior art]
In general, lithium ion secondary batteries having a high volumetric energy density and a high weight energy density are used in mobile wireless communication devices such as mobile phones and cordless phones, as well as video cameras and laptop computers. This lithium ion secondary battery is usually used as a power source for the electronic device by connecting a plurality of single cells (single cells) in series.
[0003]
Conventionally, charging of lithium-ion secondary batteries and other batteries is performed by setting the charging voltage to a constant value of 4.1 V or 4.2 V per unit cell, and charging at a constant current value until the battery voltage reaches these charging completion voltages. Then, after reaching the charging completion voltage, a constant current / constant voltage charging method is adopted that shifts to constant voltage charging.
On the other hand, the charging of the lithium ion secondary batteries connected in series is fixed until, for example, the charging completion voltage per unit cell is 4.1 V, and the number of cells connected in series is n × 4.1 V. Current charging is performed (see FIG. 3).
[0004]
However, in the constant current / constant voltage charging method described above, since the terminal voltage of each cell is not individually monitored, if there is a variation in the terminal voltage of each cell during charging, any cell reaches the charge completion voltage. However, since the other batteries have not reached the charging completion voltage, charging is continued, and the cell that has reached the charging completion voltage first is overcharged.
[0005]
[Problems to be solved by the invention]
When a plurality of lithium ion secondary batteries connected in series are used in a trickle charging method, charging can be performed with a good balance if the capacity or internal resistance of all the batteries is always the same.
In practice, however, there is some variation in battery capacity or internal resistance. Furthermore, even if the internal resistance is the same at the initial stage, the internal characteristics of the battery change as time passes due to trickle charging, and the capacity and internal resistance of the battery also change. As a result, the balance of each battery is lost, and a specific battery may be overcharged.
[0006]
On the other hand, since the other batteries are charged in a state where they do not reach full charge, it is impossible to sufficiently take out the capacity of the batteries. Thus, in the conventional charging method, there are cases where each battery cannot be reliably charged to a fully charged state.
This invention is made | formed in view of such a situation, and charge of the assembled battery which is waiting by the trickle charge system about the some lithium ion secondary battery connected in series is performed cheaply and efficiently. An object of the present invention is to provide a charging device for a lithium ion secondary battery that enables the above.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a plurality of lithium ion secondary batteries are connected in series with an output of a DC power supply that supplies power to a DC load in parallel with the DC load. A method of charging a lithium ion secondary battery that charges each lithium ion secondary battery that is used by being connected to an assembled battery, wherein the lithium ion secondary battery that constitutes the assembled battery is charged, and A voltage between terminals of each lithium ion secondary battery constituting the assembled battery is detected, and among the lithium ion secondary batteries constituting the assembled battery, a lithium ion secondary battery that has reached a preset charge completion voltage In contrast, the both ends of the lithium ion secondary battery are short-circuited to bypass the charging current, and after all the lithium ion secondary batteries constituting the assembled battery have reached the charge completion voltage, And performing a trickle charge for each lithium-ion secondary batteries constituting the battery.
[0008]
The invention according to claim 2 is used by connecting a battery pack in which a plurality of lithium ion secondary batteries are connected in series to the output of a DC power supply for supplying power to the DC load in parallel with the DC load. A charging device for charging each lithium ion secondary battery that is connected between terminals of the assembled battery and that constitutes the assembled battery. A voltage detection means for detecting a voltage between terminals of each lithium ion secondary battery constituting the assembled battery; and a control signal connected between and input to terminals of each lithium ion secondary battery constituting the assembled battery The bypass means for short-circuiting the terminals of the connected lithium ion secondary battery based on the above, and the detection output of the voltage detection means is taken in, and each lithium ion secondary battery constituting the assembled battery A control means for controlling the bypass means so as to short-circuit both ends of the lithium ion secondary battery sequentially with respect to the lithium ion secondary battery that has reached a preset charge completion voltage; and a positive electrode of the assembled battery The diode is connected between the positive terminal side and the DC load and the DC power supply so as to have a polarity that allows the discharge of each lithium ion secondary battery constituting the assembled battery with respect to the DC load and the DC power supply. It is characterized by having.
[0009]
According to a third aspect of the present invention, in the charging device for a lithium ion secondary battery according to the first aspect, the control means is configured such that all the lithium ion secondary batteries constituting the assembled battery have reached a charging completion voltage. The bypass means is set in a non-operating state later.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration of a charging device for a lithium ion secondary battery according to an embodiment of the present invention. The lithium-ion secondary battery charging apparatus according to the present embodiment is an assembled battery in which a plurality of lithium-ion secondary batteries are connected in series to the output of a DC power supply that supplies power to a DC load in parallel with the DC load. A method of charging a lithium ion secondary battery that charges each of the lithium ion secondary batteries used by being connected to the battery, charging each lithium ion secondary battery constituting the assembled battery, and the assembled battery The lithium ion secondary battery that detects a voltage between terminals of each lithium ion secondary battery that constitutes the battery and reaches a preset charge completion voltage among the lithium ion secondary batteries that constitute the assembled battery Sequentially, the both ends of the lithium ion secondary battery are short-circuited to bypass the charging current, and before all the lithium ion secondary batteries constituting the assembled battery reach the charging completion voltage, A device for carrying out the method of charging a lithium ion secondary battery and performing a trickle charge for each lithium-ion secondary batteries constituting the battery pack.
[0011]
In FIG. 1, a charging device for a lithium ion secondary battery according to this embodiment includes a plurality of lithium ion secondary batteries (cells) connected in parallel to the DC load 2 at the output of a DC power supply 3 that supplies power to the DC load 2. ) Charging of a lithium ion secondary battery that charges each lithium ion secondary battery that is used by being connected to an assembled battery in which 1-1, 1-2, 1-3,..., 1-n are connected in series Device.
[0012]
The lithium ion secondary battery charging device according to the present embodiment is connected between the terminals of the assembled battery, and each of the lithium ion secondary batteries 1-1, 1-2, 1-3,. 1-n lithium ion secondary battery charger (hereinafter simply referred to as a charger) 5 and each lithium ion secondary battery 1-1, 1-2, 1-3,..., 1-n , 6-n and the lithium ion secondary batteries 1-1, 1-2, 1-3,..., 1-, and the voltage probes 6-1, 6-2, 6-3,. Bypass circuits 4-1, 4-2, 4-3,..., 4-n that are connected between n terminals and short-circuit between the terminals of the connected lithium ion secondary batteries based on an input control signal. , 6-n of the voltage probes 6-1, 6-2, 6-3,. 1, 1-2, 1-3,..., 1-n are sequentially short-circuited between both ends of the lithium ion secondary battery that has reached a preset charge completion voltage. Between the control circuit 7 for controlling the bypass circuits 4-1, 4-2, 4-3,..., 4-n, the positive terminal side of the assembled battery, the DC load 2 and the DC power source 3, The lithium ion secondary batteries 1-1, 1-2, 1-3,..., 1-n constituting the assembled battery with respect to the DC load 2 and the DC power supply 3 have a polarity that allows discharging. And a diode 10 to be connected.
[0013]
Each of the bypass circuits 4-1, 4-2, 4-3,..., 4-n includes a first IGBT (Insulated Gate Bipolar Transistor) and a second IGBT connected between both ends of each lithium ion secondary battery. 1 and a diode connected between the emitter and collector of the first IGBT with the polarity shown in FIG. For example, the bypass circuit 4-1 includes a series circuit of IGBT: P1 and IGBT: Q1, and a diode D1 connected between the emitter and collector of IGBT: P1.
Here, the collector of IGBT: P1 is connected to the positive electrode of the lithium ion secondary battery 1-1, the emitter of IGBT: P1 is connected to the collector of IGBT: Q1, and the emitter of IGBT: Q1 is the lithium ion secondary battery 1- 1 are respectively connected to the negative electrode.
[0014]
The DC power source 3 converts AC commercial power (not shown in the figure) into DC power and supplies it to the DC load 2.
On the other hand, a set of a plurality of lithium ion secondary batteries 1-1, 1-2, 1-3,..., 1-n connected in series so that power can be supplied to the DC load 2 without interruption in the event of a power failure. A battery is connected between both ends of the DC load 2 via bypass circuits 4-1, 4-2, 4-3,.
[0015]
Further, voltage probes 6-1, 6-2, 6-3,..., 6 -n that detect terminal voltages of the respective cells (lithium ion secondary batteries) are connected to the control unit 7.
Further, the control unit 7 supplies an IGBT control line for supplying a control signal instructing the bypass circuit 4-1, 4-2, 4-3,. , 8-2, 8-3,..., 8-n are connected to the bypass circuits 4-1, 4-2, 4-3,. It is connected to the charger 5 through a charge control line 9 that outputs a control signal for performing control.
[0016]
The control unit 7 takes in the detection outputs of the voltage probes 6-1, 6-2, 6-3,..., 6-n, and the battery voltage of each lithium ion secondary battery, that is, the voltage between terminals is set in advance. When the detected state is detected, the charging current is bypassed via any of the IGBT control lines 8-1, 8-2, 8-3,..., 8-n corresponding to the detected lithium ion secondary battery. The control signal is output, and the IGBT of the corresponding bypass circuit 4 (4-1, 4-2, 4-3,..., 4-n) is operated to bypass the charging current when the charging completion voltage is reached. It has a function to make it.
[0017]
Next, the operation of the charging apparatus for a lithium ion secondary battery according to the embodiment of the present invention having the above-described configuration will be described with reference to FIGS.
The battery pack that has been discharged is charged by the charger 5 under the control of the control unit 7 with all the IGBTs in the bypass circuits 4-1, 4-2, 4-3,. Is called. Charging is performed by constant current-constant voltage control. When the charging completion voltage per unit cell is 4.1 V, the charging completion voltage of an assembled battery in which n single cells (lithium ion secondary batteries) are connected in series is n. X4.1V, and charging is performed at a constant current up to this voltage.
[0018]
Ideally, when charging, the terminal voltage of each lithium ion secondary battery (cell) 1-1, 1-2, 1-3,..., 1-n is 4.1 V in the same charging time. Actually, since the internal characteristics or capacities of the batteries are imbalanced, for example, as shown in FIG. 4, in the conventional charging method, only the charging voltage V 1-n of the cell 1-n is the charging completion voltage at time t0. 4.1V, and other cells do not reach the charge completion voltage. As described above, if the cell 1-n continues to be charged after reaching the charge completion voltage, the cell 1-n that has already reached the charge completion voltage is overcharged, which is dangerous.
[0019]
In the present invention, the control unit 7 takes in the detection output of the voltage probes 6-1, 6-2, 6-3,..., 6-n, and the battery voltage of each lithium ion secondary battery, that is, between the terminals. When the voltage reaches a preset charging completion voltage, the IGBT control lines 8-1, 8-2, 8-3,... Corresponding to the lithium ion secondary battery whose inter-terminal voltage has reached the charging completion voltage. , 8-n, a control signal for bypassing the charging current is output to a bypass circuit corresponding to the lithium ion secondary battery that has reached the charging completion voltage.
[0020]
For example, IGBTs P1, P2, P3,..., Added to the lithium ion secondary batteries 1-1, 1-2, 1-3,. Bypass circuits 4 (4-1, 4-2, 4-3,...) Provided between terminals of the lithium ion secondary batteries that have reached the charge completion voltage by controlling Pn, Q1, Q2, Q3,. , 4-n), by bypassing the charging current, as shown in FIG. 5, the overcharging of the lithium ion secondary battery that has already reached the charging completion voltage is prevented, and the charging of each lithium ion secondary battery is performed. The voltage can be made uniform.
[0021]
Referring to the example of FIG. 5, at time t0, the control unit 7 turns on IGBT: Qn in the bypass circuit 4-n provided between the terminals of the cell 1-n that first reaches the charge completion voltage and turns on the charging current. Bypass. This operation is performed in order from the cell that has reached the charging completion voltage, and is continued until all cells are completed. After each cell reaches the charge completion voltage, all IGBTs in the bypass circuits 4-1, 4-2, 4-3,..., 4-n are set to QFF, and the control unit 7 passes the charge control line 9 Upon receiving the control signal, the charger 5 immediately shifts to the assembled battery trickle charging, so that all cells can be prepared for emergency battery discharge in a fully charged state.
[0022]
In the embodiment of the present invention, the diode 10 includes the positive terminal side of the assembled battery including the lithium ion secondary batteries 1-1, 1-2, 1-3,. Connected to the power source 3 so as to have a polarity allowing the discharge of the lithium ion secondary batteries 1-1, 1-2, 1-3,..., 1-n to the DC load 2 and the DC power source 3. Therefore, the lithium ion secondary batteries 1-1, 1-2, 1-3,..., 1-n are charged by the charger 5 while preventing charging from the DC power source 3. be able to.
In addition, when the power consumption of the DC load 2 is increased during the charging of the battery, the assembled battery or the charging including the lithium ion secondary batteries 1-1, 1-2, 1-3,. It is also possible to supply power to the DC load 2 from the device 5.
[0023]
According to the lithium ion secondary battery charging apparatus according to the embodiment of the present invention, the battery voltage of each of the plurality of lithium ion secondary batteries (cells) connected in series is detected, and any one cell is completely charged. The battery is charged until it reaches the voltage, and after any one cell reaches the charge completion voltage, the charge current is bypassed by controlling the IGBT that constitutes the bypass circuit provided for the charged cell. By charging one cell at a time until the other cells reach the charge completion voltage, the terminal voltage imbalance between the cells can be easily eliminated.
[0024]
【The invention's effect】
As described above, according to the present invention, each lithium ion secondary battery constituting the assembled battery is charged, and the terminal voltage of each lithium ion secondary battery constituting the assembled battery is detected. The lithium ion secondary battery that has reached a preset charge completion voltage among the lithium ion secondary batteries constituting the assembled battery is sequentially shorted between both ends of the lithium ion secondary battery to charge current. The trickle charging is performed on each lithium ion secondary battery constituting the assembled battery after all the lithium ion secondary batteries constituting the assembled battery reach the charging completion voltage. It becomes possible to charge the assembled battery that is waiting in the trickle charging method for a plurality of connected lithium ion secondary batteries at low cost and efficiently.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a charging device for a lithium ion secondary battery according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing opening / closing timings of IGBTs constituting a bypass circuit in the lithium ion secondary battery charging apparatus according to the embodiment of the present invention shown in FIG. 1;
FIG. 3 is an explanatory diagram showing voltage and current characteristics when charging a battery pack of a conventional lithium ion secondary battery.
FIG. 4 is an explanatory diagram showing voltage and current characteristics when charging a single lithium ion secondary battery.
FIG. 5 is an explanatory diagram showing voltage and current characteristics when charging a single cell of a lithium ion secondary battery in a lithium ion secondary battery charging apparatus according to an embodiment of the present invention.
[Explanation of symbols]
1-1, 1-2, 1-3,..., 1-n Lithium ion secondary battery 2 DC load 3 DC power sources 4-1, 4-2, 4-3,. Circuit 5 ... Lithium ion secondary battery chargers 6-1, 6-2, 6-3, ..., 6-n ... Voltage probe 7 ... Control units 8-1, 8-2, 8-3, ..., 8 -N ... IGBT control line 9 ... charge control line 10 ... diode

Claims (3)

直流負荷に電力を供給する直流電源の出力に、前記直流負荷と並列に、複数のリチウムイオン二次電池が直列接続されてなる組電池が接続されて使用される前記各リチウムイオン二次電池の充電を行うリチウムイオン二次電池の充電装置であって、
前記組電池の端子間に接続され、前記組電池を構成する各リチウムイオン二次電池に充電電流を流して充電を行う充電手段と、
該充電手段の前記直流電源の正極性端子側と、前記直流電源の正極性端子側との間に、該直流負荷及び直流電源に対して前記組電池及び前記充電手段からの放電を許容する極性となるように接続されるダイオードと、
前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出する電圧検出手段と、
前記組電池を構成する各リチウムイオン二次電池の端子間毎に接続され、入力される制御信号に基づいて該接続されたリチウムイオン二次電池の端子間を短絡するバイパス手段と、
前記電圧検出手段の検出出力を取り込み、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡するように前記バイパス手段を制御する制御手段と、
を有することを特徴とするリチウムイオン二次電池の充電装置。Each of the lithium ion secondary batteries used is connected to an output of a direct current power source that supplies power to the direct current load, and a plurality of lithium ion secondary batteries are connected in parallel with the direct current load. A charging device for a lithium ion secondary battery that performs charging,
The battery pack is connected between the terminals of a charging means for charging by supplying a charging current to each of the lithium ion secondary batteries constituting the battery pack,
Between the positive terminal side of the DC power source of the charging unit and the positive terminal side of the DC power source, the polarity allowing discharge from the assembled battery and the charging unit to the DC load and DC power source A diode connected to be
Voltage detecting means for detecting a voltage between terminals of each lithium ion secondary battery constituting the assembled battery;
And bypass means for short-circuiting between the battery pack is connected to each between terminals of the lithium ion secondary batteries constituting the, of the connected lithium ion secondary battery based on the control signal input terminal,
The detection output of the voltage detection means is captured, and the lithium ion secondary battery is sequentially applied to the lithium ion secondary batteries that have reached a preset charge completion voltage among the lithium ion secondary batteries constituting the assembled battery. Control means for controlling the bypass means so as to short-circuit both ends of
A charging device for a lithium ion secondary battery, comprising: 前記組電池を構成する各リチウムイオン二次電池を充電し、かつ前記組電池を構成する各リチウムイオン二次電池の端子間電圧を検出すると共に、前記組電池を構成する各リチウムイオン二次電池のうち予め設定された充電完了電圧に達したリチウムイオン二次電池に対して順次、該リチウムイオン二次電池の両端間を短絡して充電電流をバイパスし、前記組電池を構成する全てのリチウムイオン二次電池が充電完了電圧に達した後に前記組電池を構成する各リチウムイオン二次電池に対してトリクル充電を行うことを特徴とする請求項１に記載のリチウムイオン二次電池の充電装置。Recharge each lithium ion secondary battery constituting the assembled battery, and detect a voltage between terminals of each lithium ion secondary battery constituting the assembled battery, and each lithium ion secondary battery constituting the assembled battery Among the lithium-ion secondary batteries that have reached a preset charging completion voltage, by short-circuiting both ends of the lithium-ion secondary battery to bypass the charging current, and all the lithium constituting the assembled battery 2. The charging device for a lithium ion secondary battery according to claim 1, wherein trickle charging is performed on each lithium ion secondary battery constituting the assembled battery after the ion secondary battery reaches a charging completion voltage. . 前記バイパス手段は、
前記リチウムイオン二次電池に直列に接続され、ダイオードと第１のスイッチ素子とが並列接続された回路と、
該回路及び前記リチウムイオン二次電池の直列接続に対して並列に接続された第２のスイッチ素子と
から構成されていることを特徴とする請求項１または請求項２に記載のリチウムイオン二次電池の充電装置。The bypass means includes
A circuit connected in series to the lithium ion secondary battery, in which a diode and a first switch element are connected in parallel;
A second switch element connected in parallel to the series connection of the circuit and the lithium ion secondary battery;
The charging device for a lithium ion secondary battery according to claim 1 or 2, wherein
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KR102268682B1 (en) * 2017-06-13 2021-06-22 주식회사 엘지에너지솔루션 Apparatus and method for preventing over-voltage
GB2576182B (en) 2018-08-08 2022-04-06 Renewable Energy Dynamics Tech Ltd Flow battery
JP6970136B2 (en) * 2019-04-04 2021-11-24 矢崎総業株式会社 Battery control unit and battery system

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