JP2009033843A - Apparatus and method for charging - Google Patents

Apparatus and method for charging Download PDF

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JP2009033843A
JP2009033843A JP2007194219A JP2007194219A JP2009033843A JP 2009033843 A JP2009033843 A JP 2009033843A JP 2007194219 A JP2007194219 A JP 2007194219A JP 2007194219 A JP2007194219 A JP 2007194219A JP 2009033843 A JP2009033843 A JP 2009033843A
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charging
current
voltage
constant
constant current
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Masaaki Sakagami
正昭 阪上
Toshiharu Ohashi
敏治 大橋
Masatoshi Ito
正俊 伊藤
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Panasonic Electric Works Co Ltd
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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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for charging wherein the time of exposure to the maximum voltage in constant-voltage charging can be minimized to lengthen the life of a battery. <P>SOLUTION: The following charging method is carried out by a charge control unit 12. First constant-current charging is started. When the voltage of a secondary battery 21 reaches a first voltage value V0, the first constant-current charging is terminated. First constant-voltage charging in which current is gradually lowered from the first constant current I1 is started. When the charging current is lowered to a first threshold current Iend0, the first constant-voltage charging is terminated. Second constant-current charging is started with a second constant current larger than the first threshold current Iend0. When the voltage of the secondary battery 21 reaches a second voltage value V1 larger than the first voltage value V0, the second constant-current charging is terminated. Second constant-voltage charging in which current is gradually lowered from the second constant current is started. When the charging current is lowered to a second threshold current Iend1, the second constant-voltage charging is terminated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、例えばリチウムイオン電池等の二次電池を充電する充電装置および充電方法に係り、特に、定電圧充電における最大電圧に晒される時間を最小限に抑えて電池の寿命を延ばし得る充電装置および充電方法に関する。   The present invention relates to a charging device and a charging method for charging a secondary battery such as a lithium ion battery, and more particularly to a charging device capable of extending the life of a battery by minimizing the time exposed to the maximum voltage in constant voltage charging. And a charging method.

近年、電動工具や携帯機器などの電気機器の駆動電源として、リチウムイオン二次電池やニッケル水素二次電池などの種々の二次電池が汎用されている。このような二次電池では、過充電されると、電池パックが破損したり、電池寿命を縮めてしまうことになる。特にリチウムイオン二次電池において、過充電による悪影響が顕著である。二次電池の過充電を防止するためには、少ない充電電流でゆっくり充電し、二次電池の電圧が所定値に達したら充電を停止するようにすればよい。しかし、充電電流を少なくすると、充電時間が増大してしまう。   In recent years, various secondary batteries such as lithium ion secondary batteries and nickel metal hydride secondary batteries have been widely used as drive power sources for electric devices such as electric tools and portable devices. If such a secondary battery is overcharged, the battery pack may be damaged or the battery life may be shortened. Particularly in a lithium ion secondary battery, the adverse effects due to overcharging are significant. In order to prevent overcharging of the secondary battery, it is only necessary to slowly charge with a small charging current and stop charging when the voltage of the secondary battery reaches a predetermined value. However, if the charging current is reduced, the charging time increases.

そこで、図４に示すように、充電開始直後から、一定の電流Ｉ１で急速充電を行い、ある程度二次電池の電圧が上昇してから所定の定電圧Ｖ１を二次電池に印加する定電圧充電に切り替え、その後二次電池の充電が進むと共に充電電流を減少させて、充電電流が所定値Ｉｅｎｄを下回ったら充電を停止させ、二次電池の過充電を防止するようにした充電装置が知られている（例えば、特許文献１参照）。
特開平１０−６６２７７号公報 Therefore, as shown in FIG. 4, constant voltage charging is performed by performing rapid charging with a constant current I1 immediately after the start of charging, and applying a predetermined constant voltage V1 to the secondary battery after the voltage of the secondary battery rises to some extent. There is known a charging device that prevents the secondary battery from being overcharged by stopping the charging when the charging current falls below a predetermined value Iend as the charging of the secondary battery proceeds and then the charging current is decreased. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 10-66277

しかしながら、このような定電流充電から定電圧充電への切り換え充電方式で充電する電池には寿命があり、充放電を繰り返すと、充放電容量が低下してついには使えなくなるという事情があった。ここで、電池の寿命を長くするには定電圧充電において一定電圧（Ｖ１）に晒されている時間をできる限り短くすることが有効である。   However, a battery that is charged by such a charging method that switches from constant current charging to constant voltage charging has a life, and when charging and discharging are repeated, the charging / discharging capacity decreases and eventually becomes unusable. Here, in order to extend the life of the battery, it is effective to shorten the time during which the battery is exposed to the constant voltage (V1) in constant voltage charging as much as possible.

本発明は、上記従来の事情に鑑みてなされたものであって、定電圧充電における最大電圧に晒される時間を最小限に抑えて電池の寿命を延ばし得る充電装置および充電方法を提供することを目的としている。   The present invention has been made in view of the above-described conventional circumstances, and provides a charging device and a charging method that can extend the life of a battery by minimizing the time of exposure to the maximum voltage in constant voltage charging. It is aimed.

上記目的を達成するために、本発明に係る充電装置は、二次電池へ電力を供給する電源部と、前記二次電池の電圧を検出する電圧測定部と、前記二次電池へ供給される充電電流を検出する電流測定部と、前記電源部の動作を制御する充電制御部と、を備えた充電装置であって、前記充電制御部は、第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該第１の定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了し、次に、前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了し、次に、前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了することを第１の特徴とする。   In order to achieve the above object, a charging device according to the present invention is supplied to a power supply unit that supplies power to a secondary battery, a voltage measurement unit that detects a voltage of the secondary battery, and the secondary battery. A charging apparatus comprising: a current measuring unit that detects a charging current; and a charging control unit that controls the operation of the power supply unit, wherein the charging control unit includes a first constant current charging with a first constant current. The first constant current charging is completed when the voltage of the secondary battery reaches a first voltage value after starting the operation, and then the current is gradually decreased from the first constant current. When the first constant voltage charging with the first voltage value is started and the charging current decreases to the first threshold current, the first constant voltage charging is completed, and then, from the first threshold current Starting the second constant current charging with a large second constant current, the voltage of the secondary battery is equal to the first voltage value. The second constant current charging is completed when the second voltage value is larger than the second constant current, and then the current is gradually decreased from the second constant current. The first characteristic is that the second constant voltage charging is completed when the constant voltage charging is started and the charging current is reduced to the second threshold current.

また、本発明に係る充電装置は、前記充電制御部は、前記第１の定電圧充電および前記第２の定電圧充電において、充電電流を段階的に下げて行くことを第２の特徴とする。   In addition, the charging device according to the present invention has a second feature that the charging control unit gradually decreases a charging current in the first constant voltage charging and the second constant voltage charging. .

また、本発明に係る充電装置は、前記充電制御部により、第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該第１の定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了し、次に、前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了し、次に、前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了する第１の充電モードと、第１の定電流による定電流充電を開始して前記二次電池の電圧が前記第２の電圧値に達したときに該定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第２の電圧値による定電圧充電を開始して充電電流が前記第２の閾値電流まで低下したときに該定電圧充電を完了する第２の充電モードと、を切り換えるスイッチを備えることを第３の特徴とする。   In the charging device according to the present invention, when the charging control unit starts the first constant current charging with the first constant current and the voltage of the secondary battery reaches the first voltage value, The first constant current charging is completed, and then the first constant voltage charging is started with the first voltage value gradually decreasing the current from the first constant current. The first constant voltage charging is completed when the current falls to the threshold current, and then the second constant current charging is started by the second constant current larger than the first threshold current to The second constant current charging is completed when the voltage reaches a second voltage value larger than the first voltage value, and then the current is gradually decreased from the second constant current. When the second constant voltage charging by the second voltage value is started and the charging current is reduced to the second threshold current, the second constant voltage is A first charging mode for completing charging, and starting constant current charging by a first constant current, and completing the constant current charging when the voltage of the secondary battery reaches the second voltage value; Next, constant voltage charging with the second voltage value starting from the first constant current is gradually reduced, and when the charging current decreases to the second threshold current, the constant voltage charging is performed. A third feature is that a switch for switching between the second charging mode to be completed is provided.

さらに、本発明に係る充電方法は、二次電池へ電力を供給する電源部と、前記二次電池の電圧を検出する電圧測定部と、前記二次電池へ供給される充電電流を検出する電流測定部と、前記電源部の動作を制御する充電制御部と、を備えた充電装置の充電方法であって、第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該該第１の定電流充電を完了する第１の定電流充電ステップと、前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了する第１の定電圧充電ステップと、前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了する第２の定電流充電ステップと、前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了する第２の定電圧充電ステップと、を備えることを第４の特徴とする。   Furthermore, the charging method according to the present invention includes a power supply unit that supplies power to a secondary battery, a voltage measurement unit that detects a voltage of the secondary battery, and a current that detects a charging current supplied to the secondary battery. A charging method for a charging device comprising: a measuring unit; and a charging control unit that controls the operation of the power supply unit, wherein the first constant current charging by a first constant current is started and the secondary battery A first constant current charging step for completing the first constant current charging when the voltage reaches a first voltage value; and the first constant current gradually decreasing from the first constant current. A first constant voltage charging step of starting the first constant voltage charging by the voltage value and completing the first constant voltage charging when the charging current decreases to the first threshold current; and the first threshold value. A voltage of the secondary battery is started by starting a second constant current charging with a second constant current larger than the current. A second constant current charging step for completing the second constant current charging when a second voltage value larger than the first voltage value is reached, and gradually decreasing the current from the second constant current A second constant voltage charging step of starting the second constant voltage charging by the second voltage value and completing the second constant voltage charging when the charging current decreases to the second threshold current; The fourth feature is to provide

本発明に係る充電装置および充電方法では、定電圧充電における最大電圧に晒される時間を最小限に抑えて、電池の寿命を延ばし得る充電装置および充電方法を実現することができる。   With the charging device and the charging method according to the present invention, it is possible to realize a charging device and a charging method that can extend the life of the battery by minimizing the time of exposure to the maximum voltage in constant voltage charging.

以下、本発明の充電装置および充電方法の実施例について、〔実施例〕、〔変形例〕の順に図面を参照して詳細に説明する。   Hereinafter, embodiments of the charging device and the charging method of the present invention will be described in detail in the order of [Embodiment] and [Modification] with reference to the drawings.

〔実施例〕
図１は本発明の実施例に係る充電装置の構成図である。同図において、本実施例の充電装置は、充電器１および電池パック２を含む構成である。 〔Example〕
FIG. 1 is a configuration diagram of a charging apparatus according to an embodiment of the present invention. In the figure, the charging device of the present embodiment includes a charger 1 and a battery pack 2.

電池パック２は、電池セルＥ１〜Ｅｎが複数個直列に接続された二次電池２１と、各電池セルＥ１〜Ｅｎの電圧を、単段でまたは２〜３段纏めて測定する電圧判定回路２２と、充電器１の接続端子Ｔ１１〜Ｔ１３に対応する接続端子Ｔ２１〜Ｔ２３とを備えて構成される。電池セルＥ１〜Ｅｎは、リチウムイオン電池等から成り、複数の電池セルが並列に接続されて構成されてもよく、また単段構成の場合は、電圧判定回路２２の機能は充電器１側の電圧測定部１３で実現できるので、該電圧判定回路２２は省略されてもよい。なお、電圧判定回路２２は、各段の電池セルＥ１〜Ｅｎの電圧を測定し、何れかの電池セルが予め定める目標電圧Ｖ１に達すると過充電信号をアクティブのローレベルとし、達していないと該過充電信号を非アクティブのハイレベルとして、接続端子Ｔ２３，Ｔ１３を介して充電制御部１２へ出力する。   The battery pack 2 includes a secondary battery 21 in which a plurality of battery cells E1 to En are connected in series, and a voltage determination circuit 22 that measures the voltage of each battery cell E1 to En in a single stage or in two to three stages. And connection terminals T21 to T23 corresponding to the connection terminals T11 to T13 of the charger 1. The battery cells E1 to En are composed of lithium ion batteries or the like, and may be configured by connecting a plurality of battery cells in parallel. In the case of a single stage configuration, the function of the voltage determination circuit 22 is the function of the charger 1 side. Since it can be realized by the voltage measurement unit 13, the voltage determination circuit 22 may be omitted. The voltage determination circuit 22 measures the voltages of the battery cells E1 to En at each stage, and when any of the battery cells reaches a predetermined target voltage V1, the overcharge signal is set to an active low level. The overcharge signal is set to an inactive high level and is output to the charge control unit 12 via the connection terminals T23 and T13.

一方、充電器１は、電圧検知部１３と、電流測定部１４と、定電流回路１５及び定電圧回路１６を含む電源部１１と、充電制御部１２と、を備えた構成である。なお、スイッチＳＷ１については変形例において後述する。   On the other hand, the charger 1 includes a voltage detection unit 13, a current measurement unit 14, a power supply unit 11 including a constant current circuit 15 and a constant voltage circuit 16, and a charge control unit 12. The switch SW1 will be described later in a modification.

電源部１１は、例えばＡＣ−ＤＣコンバータとして構成された電源回路で、電源線を介して接続された商用電源３から供給された交流電圧を直流電圧に変換する。そして、電源部１１における正極側出力端子は、接続端子Ｔ１１，Ｔ２３を介して二次電池２１の正極端子に接続され、電源部１１における負極側出力端子は、電流測定部１４、接続端子Ｔ１２，Ｔ２２を介して二次電池２１の負極端子に接続されている。   The power supply unit 11 is a power supply circuit configured as an AC-DC converter, for example, and converts an AC voltage supplied from a commercial power supply 3 connected via a power supply line into a DC voltage. The positive output terminal in the power supply unit 11 is connected to the positive terminal of the secondary battery 21 via the connection terminals T11 and T23, and the negative output terminal in the power supply unit 11 is the current measurement unit 14, the connection terminal T12, It is connected to the negative terminal of the secondary battery 21 via T22.

定電流回路１５は、充電制御部１２からの制御信号に応じて電源部１１から電池パック２へ供給される二次電池２１の充電電流を調整する。また、定電圧回路１６は、充電制御部１２からの制御信号に応じて電源部１１から電池パック２へ供給される二次電池２１の充電電圧を調整する。   The constant current circuit 15 adjusts the charging current of the secondary battery 21 supplied from the power supply unit 11 to the battery pack 2 in accordance with a control signal from the charging control unit 12. The constant voltage circuit 16 adjusts the charging voltage of the secondary battery 21 supplied from the power supply unit 11 to the battery pack 2 in accordance with a control signal from the charging control unit 12.

また、電圧検知部１３は、接続端子Ｔ１１，Ｔ１２間の電圧、即ち二次電池２１における端子電圧を検出する回路部で、例えば抵抗体を用いて構成されており、その抵抗体の電圧降下により生じた電圧を、電圧検知信号として充電制御部１２へ出力する。   Moreover, the voltage detection part 13 is a circuit part which detects the voltage between the connection terminals T11 and T12, ie, the terminal voltage in the secondary battery 21, and is comprised using a resistor, for example, and the voltage drop of the resistor The generated voltage is output to the charge control unit 12 as a voltage detection signal.

また、電流測定部１４は、電源部１１から接続端子Ｔ１２，Ｔ２２を介して二次電池２３へ供給される充電電流を検出する回路部で、例えばホール素子を用いた電流センサや抵抗体によって充電電流を電圧に変換することにより得られた電流検知信号を充電制御部１２へ出力する。   The current measuring unit 14 is a circuit unit that detects a charging current supplied from the power supply unit 11 to the secondary battery 23 via the connection terminals T12 and T22. For example, the current measuring unit 14 is charged by a current sensor or a resistor using a Hall element. A current detection signal obtained by converting the current into a voltage is output to the charge control unit 12.

さらに、充電制御部１２は、例えば所定の演算処理を実行するＣＰＵ（Central Processing Unit）と、所定の制御プログラムが記録された不揮発性の記憶素子であるＲＯＭ（Read Only Memory）と、データを一時的に記録する揮発性の記憶素子であるＲＡＭ（Random Access Memory）と、電圧検知信号および電流検知信号をデジタル値に変換するＡＤコンバータとを備えて構成され、ＲＯＭに記憶された制御プログラムを実行することにより、電源部１１（定電流回路１５および定電圧回路１６）へ制御信号を出力して二次電池２１の充電動作を制御する。   Furthermore, the charging control unit 12 temporarily stores data such as a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that is a nonvolatile storage element in which a predetermined control program is recorded, and data. Random Access Memory (RAM), which is a volatile storage element that automatically records, and an AD converter that converts voltage detection signals and current detection signals into digital values, and executes a control program stored in ROM Thus, a control signal is output to the power supply unit 11 (constant current circuit 15 and constant voltage circuit 16) to control the charging operation of the secondary battery 21.

次に、以上のように構成された電池パック２および充電器１が結合されたときに、充電制御部１２の制御の下に行われる充電動作について、図２および図３（ａ）〜（ｃ）を参照して詳細に説明する。ここで、図２は実施例の充電動作を説明するフローチャートであり、図３は実施例の充電動作を説明する説明図であり、図３（ａ）は二次電池２１の電池電圧の時間的推移を、図３（ｂ）は充電電流の時間的推移を、図３（ｃ）は動作状態の時間的推移をそれぞれ示す。なお、図３（ｄ）は変形例における充電電流の時間的推移であり、これについては後述する。   Next, regarding the charging operation performed under the control of the charging control unit 12 when the battery pack 2 and the charger 1 configured as described above are combined, FIGS. 2 and 3A to 3C. ) Will be described in detail. Here, FIG. 2 is a flowchart for explaining the charging operation of the embodiment, FIG. 3 is an explanatory view for explaining the charging operation of the embodiment, and FIG. 3 (a) shows the time of the battery voltage of the secondary battery 21. FIG. 3 (b) shows the time transition of the charging current, and FIG. 3 (c) shows the time transition of the operating state. Note that FIG. 3D shows a temporal transition of the charging current in the modified example, which will be described later.

図２において、まず、電源投入用プラグを介して商用電源３から充電器１に通電され（ステップＳ１０１）、電池パック２が挿入されて電池パック２および充電器１が結合されると（ステップＳ１０２）、充電器１は電池パック２への充電を開始する。   In FIG. 2, first, the charger 1 is energized from the commercial power source 3 through the power-on plug (step S101), and when the battery pack 2 is inserted and the battery pack 2 and the charger 1 are coupled (step S102). ), The charger 1 starts charging the battery pack 2.

すなわち、第１の定電流Ｉ１による第１の定電流充電（ステップＳ１０４）を開始して、二次電池２１の電圧が第１の電圧値Ｖ０まで上昇するまでこの第１の定電流充電を行う（ステップＳ１０５）。   That is, the first constant current charging (step S104) by the first constant current I1 is started, and the first constant current charging is performed until the voltage of the secondary battery 21 rises to the first voltage value V0. (Step S105).

二次電池２１の電圧が第１の電圧値Ｖ０に達すると、第１の定電流充電（ステップＳ１０４）を完了し、次に、第１の電圧値Ｖ０による第１の定電圧充電を開始して、図３（ｂ）に示すように第１の定電流Ｉ１から徐々に連続的に電流を下げて行く（ステップＳ１０６）。この第１の定電圧充電（ステップＳ１０６）は、充電電流が第１の閾値電流Ｉｅｎｄ０まで低下したときに完了する（ステップＳ１０７）。   When the voltage of the secondary battery 21 reaches the first voltage value V0, the first constant current charging (step S104) is completed, and then the first constant voltage charging with the first voltage value V0 is started. Then, as shown in FIG. 3 (b), the current is gradually decreased continuously from the first constant current I1 (step S106). The first constant voltage charging (step S106) is completed when the charging current is reduced to the first threshold current Iend0 (step S107).

次に、第１の閾値電流Ｉｅｎｄ０より大きい第２の定電流による第２の定電流充電（ステップＳ１０８）を開始して、二次電池２１の電圧が第１の電圧値Ｖ０よりも大きい第２の電圧値Ｖ１まで上昇するまでこの第２の定電流充電を行う（ステップＳ１０９）。   Next, the second constant current charging (step S108) with the second constant current larger than the first threshold current Iend0 is started, and the voltage of the secondary battery 21 is larger than the first voltage value V0. The second constant current charging is performed until the voltage value V1 rises (step S109).

二次電池２１の電圧が第２の電圧値Ｖ１に達すると、第２の定電流充電（ステップＳ１０８）を完了し、次に、第２の電圧値Ｖ１による第２の定電圧充電を開始して、図３（ｂ）に示すように第２の定電流から徐々に連続的に電流を下げて行く（ステップＳ１１０）。この第２の定電圧充電（ステップＳ１１０）は、充電電流が第２の閾値電流Ｉｅｎｄ１まで低下したとき（ステップＳ１１１）に完了する（ステップＳ１１２）。   When the voltage of the secondary battery 21 reaches the second voltage value V1, the second constant current charging (step S108) is completed, and then the second constant voltage charging with the second voltage value V1 is started. Then, as shown in FIG. 3B, the current is gradually decreased continuously from the second constant current (step S110). The second constant voltage charging (step S110) is completed when the charging current is reduced to the second threshold current Iend1 (step S111) (step S112).

以上のような充電動作により、図３（ａ）に示す本実施例の二次電池２１の電池電圧の時間的推移と図４（ａ）に示す従来の二次電池の電池電圧の時間的推移とを対比して分かるように、本実施例では定電圧充電における最大電圧Ｖ１に晒される時間が第２の定電圧充電の期間のみとなり、定電圧充電における最大電圧Ｖ１に晒される時間を最小限に抑えることができ、その結果として二次電池２１の寿命を延ばすことができる。   With the above charging operation, the time transition of the battery voltage of the secondary battery 21 of the present embodiment shown in FIG. 3A and the time transition of the battery voltage of the conventional secondary battery shown in FIG. As can be seen from the above, in this embodiment, the time exposed to the maximum voltage V1 in constant voltage charging is only the second constant voltage charging period, and the time exposed to the maximum voltage V1 in constant voltage charging is minimized. As a result, the life of the secondary battery 21 can be extended.

以上説明したように、本実施例の充電装置および充電方法では、充電制御部１２により、第１の定電流Ｉ１による第１の定電流充電を開始して二次電池２１の電圧が第１の電圧値Ｖ０に達したときに該第１の定電流充電を完了し、次に、第１の定電流Ｉ１から徐々に電流を下げて行く第１の電圧値Ｖ０による第１の定電圧充電を開始して充電電流が第１の閾値電流Ｉｅｎｄ０まで低下したときに該第１の定電圧充電を完了し、次に、第１の閾値電流Ｉｅｎｄ０より大きい第２の定電流による第２の定電流充電を開始して二次電池２１の電圧が第１の電圧値Ｖ０よりも大きい第２の電圧値Ｖ１に達したときに該第２の定電流充電を完了し、次に、第２の定電流から徐々に電流を下げて行く第２の電圧値Ｖ１による第２の定電圧充電を開始して充電電流が第２の閾値電流Ｉｅｎｄ１まで低下したときに該第２の定電圧充電を完了する。   As described above, in the charging device and the charging method of the present embodiment, the charging control unit 12 starts the first constant current charging with the first constant current I1 and the voltage of the secondary battery 21 is the first voltage. When the voltage value V0 is reached, the first constant current charging is completed, and then the first constant voltage charging with the first voltage value V0 gradually decreasing from the first constant current I1 is performed. The first constant voltage charging is completed when the charging current starts to decrease to the first threshold current Iend0, and then the second constant current is generated by the second constant current larger than the first threshold current Iend0. Charging is started and the second constant current charging is completed when the voltage of the secondary battery 21 reaches the second voltage value V1 larger than the first voltage value V0. Next, the second constant current charging is completed. The second constant voltage charging with the second voltage value V1 that gradually decreases the current from the current is started and charged. Current completes the constant voltage charging the second when reduced to a second threshold current Iend1.

これにより、定電圧充電における最大電圧Ｖ１に晒される時間を最小限に抑えて、二次電池２１の寿命を延ばし得る充電装置および充電方法を実現することができる。   Accordingly, it is possible to realize a charging device and a charging method that can extend the life of the secondary battery 21 while minimizing the time of exposure to the maximum voltage V1 in constant voltage charging.

〔変形例〕
上述した実施例の充電装置および充電方法では、第１の定電圧充電（ステップＳ１０６）および第２の定電圧充電（ステップＳ１１０）において、充電電流を徐々に連続的に下げて行くようにしたが、図３（ｄ）に示すように、段階的に予め定める減分ΔＩずつ低下させるようにしても良い。 [Modification]
In the charging device and the charging method of the above-described embodiment, the charging current is gradually and continuously decreased in the first constant voltage charging (step S106) and the second constant voltage charging (step S110). As shown in FIG. 3 (d), it may be decreased step by step by a predetermined decrease ΔI.

また、図１に示すように、充電器１にスイッチＳＷ１を具備して、実施例１による充電動作（図３参照）と従来の充電動作（図４参照）とを切り換える構成としても良い。   Further, as shown in FIG. 1, the charger 1 may be provided with a switch SW1 to switch between the charging operation according to the first embodiment (see FIG. 3) and the conventional charging operation (see FIG. 4).

すなわち、スイッチＳＷ１は、第１の定電流Ｉ１による第１の定電流充電を開始して二次電池２１の電圧が第１の電圧値Ｖ０に達したときに該第１の定電流充電を完了し、次に、第１の定電流Ｉ１から徐々に電流を下げて行く第１の電圧値Ｖ０による第１の定電圧充電を開始して充電電流が第１の閾値電流Ｉｅｎｄ０まで低下したときに該第１の定電圧充電を完了し、次に、第１の閾値電流Ｉｅｎｄ０より大きい第２の定電流による第２の定電流充電を開始して二次電池２１の電圧が第１の電圧値Ｖ０よりも大きい第２の電圧値Ｖ１に達したときに該第２の定電流充電を完了し、次に、第２の定電流から徐々に電流を下げて行く第２の電圧値Ｖ１による第２の定電圧充電を開始して充電電流が第２の閾値電流Ｉｅｎｄ１まで低下したときに該第２の定電圧充電を完了する第１の充電モード（実施例の充電動作）と、第１の定電流Ｉ１による定電流充電を開始して二次電池２１の電圧が第２の電圧値Ｖ１に達したときに該定電流充電を完了し、次に、第１の定電流Ｉ１から徐々に電流を下げて行く第２の電圧値Ｖ１による定電圧充電を開始して充電電流が第２の閾値電流Ｉｅｎｄ１まで低下したときに該定電圧充電を完了する第２の充電モード（従来の充電動作）と、を切り換えるものである。   That is, the switch SW1 starts the first constant current charging with the first constant current I1, and completes the first constant current charging when the voltage of the secondary battery 21 reaches the first voltage value V0. Then, when the first constant voltage charging is started with the first voltage value V0 that gradually decreases the current from the first constant current I1, and the charging current decreases to the first threshold current Iend0. The first constant voltage charging is completed, and then the second constant current charging with the second constant current larger than the first threshold current Iend0 is started, and the voltage of the secondary battery 21 becomes the first voltage value. When the second voltage value V1 larger than V0 is reached, the second constant current charging is completed, and then the current is gradually decreased from the second constant current. 2 constant voltage charging is started and the charging current is reduced to the second threshold current Iend1 The first charging mode (the charging operation of the embodiment) for completing the constant voltage charging of 2 and the constant current charging by the first constant current I1 are started, and the voltage of the secondary battery 21 becomes the second voltage value V1. The constant current charging is completed when the current reaches, and then the constant voltage charging is started with the second voltage value V1 gradually decreasing from the first constant current I1, and the charging current reaches the second threshold value. The second charging mode (conventional charging operation) for completing the constant voltage charging when the current Iend1 is decreased is switched.

本発明の実施例に係る充電装置の構成図である。It is a block diagram of the charging device which concerns on the Example of this invention. 実施例の充電動作を説明するフローチャートである。It is a flowchart explaining the charging operation of an Example. 実施例および変形例の充電動作を説明する説明図であり、図３（ａ）は二次電池２１の電池電圧の時間的推移を、図３（ｂ）は充電電流の時間的推移を、図３（ｃ）は動作状態の時間的推移を、図３（ｄ）は変形例における充電電流の時間的推移をそれぞれ示す。FIGS. 3A and 3B are explanatory diagrams for explaining the charging operation of the embodiment and the modification, in which FIG. 3A shows the time transition of the battery voltage of the secondary battery 21, FIG. 3B shows the time transition of the charging current, and FIG. 3 (c) shows the temporal transition of the operating state, and FIG. 3 (d) shows the temporal transition of the charging current in the modified example. 従来の充電動作を説明する説明図である。It is explanatory drawing explaining the conventional charging operation.

符号の説明Explanation of symbols

１ 充電器
２ 電池パック
１１ 電源部
１２ 充電制御部
１３ 電圧測定部
１４ 電流測定部
１５ 定電流回路
１６ 定電圧回路
２１ 二次電池
２２ 電圧判定回路
Ｅ１〜Ｅｎ 電池セル
Ｔ１１〜Ｔ１３，Ｔ２１〜Ｔ２３ 接続端子
ＳＷ１ スイッチ DESCRIPTION OF SYMBOLS 1 Charger 2 Battery pack 11 Power supply part 12 Charge control part 13 Voltage measurement part 14 Current measurement part 15 Constant current circuit 16 Constant voltage circuit 21 Secondary battery 22 Voltage determination circuit E1-En Battery cell T11-T13, T21-T23 Connection Terminal SW1 switch

Claims (4)

二次電池へ電力を供給する電源部と、
前記二次電池の電圧を検出する電圧測定部と、
前記二次電池へ供給される充電電流を検出する電流測定部と、
前記電源部の動作を制御する充電制御部と、を備えた充電装置であって、
前記充電制御部は、第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該第１の定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了し、次に、前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了し、次に、前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了することを特徴とする充電装置。 A power supply for supplying power to the secondary battery;
A voltage measuring unit for detecting a voltage of the secondary battery;
A current measuring unit for detecting a charging current supplied to the secondary battery;
A charging control unit that controls the operation of the power supply unit,
The charging control unit starts the first constant current charging by the first constant current and completes the first constant current charging when the voltage of the secondary battery reaches the first voltage value, Next, when the first constant voltage charging with the first voltage value gradually decreasing from the first constant current is started and the charging current decreases to the first threshold current, the first constant current is decreased. The second constant current charging with a second constant current larger than the first threshold current is started, and the voltage of the secondary battery is higher than the first voltage value. The second constant current charging is completed when a large second voltage value is reached, and then the second constant current value is gradually decreased from the second constant current. The charging is characterized in that the second constant voltage charging is completed when the voltage charging is started and the charging current decreases to the second threshold current. Apparatus. 前記充電制御部は、前記第１の定電圧充電および前記第２の定電圧充電において、充電電流を段階的に下げて行くことを特徴とする請求項１に記載の充電装置。   2. The charging device according to claim 1, wherein the charging control unit gradually decreases a charging current in the first constant voltage charging and the second constant voltage charging. 前記充電制御部により、第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該第１の定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了し、次に、前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了し、次に、前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了する第１の充電モードと、第１の定電流による定電流充電を開始して前記二次電池の電圧が前記第２の電圧値に達したときに該定電流充電を完了し、次に、前記第１の定電流から徐々に電流を下げて行く前記第２の電圧値による定電圧充電を開始して充電電流が前記第２の閾値電流まで低下したときに該定電圧充電を完了する第２の充電モードと、を切り換えるスイッチを有することを特徴とする請求項１または請求項２の何れか１項に記載の充電装置。   The charging control unit starts first constant current charging with a first constant current and completes the first constant current charging when the voltage of the secondary battery reaches a first voltage value, Next, when the first constant voltage charging with the first voltage value gradually decreasing from the first constant current is started and the charging current decreases to the first threshold current, the first constant current is decreased. The second constant current charging with a second constant current larger than the first threshold current is started, and the voltage of the secondary battery is higher than the first voltage value. The second constant current charging is completed when a large second voltage value is reached, and then the second constant current value is gradually decreased from the second constant current. The first charging mode is completed to complete the second constant voltage charging when the voltage charging is started and the charging current is reduced to the second threshold current. And starting the constant current charging with the first constant current to complete the constant current charging when the voltage of the secondary battery reaches the second voltage value, and then the first constant current A second charging mode in which constant voltage charging is started with the second voltage value gradually decreasing from the second and the constant voltage charging is completed when the charging current decreases to the second threshold current; The charging device according to claim 1, further comprising a switch that switches between the two. 二次電池へ電力を供給する電源部と、前記二次電池の電圧を検出する電圧測定部と、前記二次電池へ供給される充電電流を検出する電流測定部と、前記電源部の動作を制御する充電制御部と、を備えた充電装置の充電方法であって、
第１の定電流による第１の定電流充電を開始して前記二次電池の電圧が第１の電圧値に達したときに該該第１の定電流充電を完了する第１の定電流充電ステップと、
前記第１の定電流から徐々に電流を下げて行く前記第１の電圧値による第１の定電圧充電を開始して充電電流が第１の閾値電流まで低下したときに該第１の定電圧充電を完了する第１の定電圧充電ステップと、
前記第１の閾値電流より大きい第２の定電流による第２の定電流充電を開始して前記二次電池の電圧が前記第１の電圧値よりも大きい第２の電圧値に達したときに該第２の定電流充電を完了する第２の定電流充電ステップと、
前記第２の定電流から徐々に電流を下げて行く前記第２の電圧値による第２の定電圧充電を開始して充電電流が第２の閾値電流まで低下したときに該第２の定電圧充電を完了する第２の定電圧充電ステップと、
を有することを特徴とする充電方法。 A power supply unit that supplies power to the secondary battery, a voltage measurement unit that detects a voltage of the secondary battery, a current measurement unit that detects a charging current supplied to the secondary battery, and an operation of the power supply unit A charging control unit for controlling, a charging method of a charging device comprising:
The first constant current charging is started by starting the first constant current charging with the first constant current and completing the first constant current charging when the voltage of the secondary battery reaches the first voltage value. Steps,
When the first constant voltage charging is started with the first voltage value that gradually decreases the current from the first constant current, and the charging current decreases to the first threshold current, the first constant voltage A first constant voltage charging step to complete charging;
When the second constant current charging by the second constant current larger than the first threshold current is started and the voltage of the secondary battery reaches a second voltage value larger than the first voltage value. A second constant current charging step for completing the second constant current charging;
When the second constant voltage charging with the second voltage value gradually decreasing from the second constant current is started and the charging current decreases to the second threshold current, the second constant voltage A second constant voltage charging step to complete charging;
A charging method characterized by comprising:
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