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JP2011062022A - Charging circuit and method - Google Patents

Charging circuit and method Download PDF

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JP2011062022A
JP2011062022A JP2009210685A JP2009210685A JP2011062022A JP 2011062022 A JP2011062022 A JP 2011062022A JP 2009210685 A JP2009210685 A JP 2009210685A JP 2009210685 A JP2009210685 A JP 2009210685A JP 2011062022 A JP2011062022 A JP 2011062022A
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power supply
supply line
charging
power
measured
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Daisuke Fujii
大輔 藤居
Takeshi Ohashi
剛 大橋
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Sony Interactive Entertainment Inc
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Sony Computer Entertainment Inc
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Priority to JP2009210685A priority Critical patent/JP2011062022A/en
Priority to PCT/JP2010/065006 priority patent/WO2011030713A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
    • H02J7/933—
    • 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

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  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

【課題】比較的エネルギー損失が少なく、かつ、実用上十分な精度で充電電流の大きさを測定できる充電回路を提供する。
【解決手段】電力供給源が出力する電力を蓄電装置に供給する電力供給線として、第１の回路要素を備える第１電力供給線１７と、第１の回路要素よりも大きな抵抗値を持つ第２の回路要素を備える第２電力供給線１８を備え、第１の回路要素の両端の電位差を測定することにより、第１電力供給線１７を流れる電流を測定し、第２の回路要素の両端の電位差を測定することにより、第２電力供給線１８を流れる電流を測定し、当該測定される電流に基づいて、蓄電装置への電力供給を制御し、第１電力供給線１７を流れる電流の測定値に応じて、蓄電装置への電力供給に用いる電力供給線を第１電力供給線１７から第２電力供給線１８に切り替える充電回路である。
【選択図】図１Provided is a charging circuit that can measure the magnitude of a charging current with a relatively small amount of energy loss and practically sufficient accuracy.
As a power supply line for supplying power output from a power supply source to a power storage device, a first power supply line having a first circuit element and a first resistance value larger than that of the first circuit element. A second power supply line 18 having two circuit elements, and by measuring a potential difference between both ends of the first circuit element, a current flowing through the first power supply line 17 is measured, and both ends of the second circuit element are measured. Is measured, the current flowing through the second power supply line 18 is measured, the power supply to the power storage device is controlled based on the measured current, and the current flowing through the first power supply line 17 is measured. The charging circuit switches the power supply line used for power supply to the power storage device from the first power supply line 17 to the second power supply line 18 in accordance with the measured value.
[Selection] Figure 1

Description

本発明は、蓄電装置を充電する充電回路及び充電方法に関する。   The present invention relates to a charging circuit and a charging method for charging a power storage device.

充電可能な二次電池等の蓄電装置を充電する際には、一般に、蓄電装置に入力される電流（充電電流）の値を監視し、充電電流が一定になるように保ったり、充電電流が予め定められた値になったタイミングで充電を終了したりする制御が行われる（例えば特許文献１参照）。そのため、蓄電装置を充電する充電回路においては、精度よく充電電流を測定することが求められる。充電電流を測定するためには、充電電流が流れる電力供給線上に配置されている回路要素（例えば電界効果トランジスタや抵抗器などの回路素子）の両端の電位差を測定する。この回路要素の抵抗値や電圧−電流特性が予め分かっていれば、測定された電圧値を用いて、回路要素を流れる電流（すなわち、充電電流）の大きさを測定することができる。   When charging a power storage device such as a rechargeable secondary battery, generally, the value of the current (charging current) input to the power storage device is monitored, and the charging current is kept constant, Control is performed such that charging is terminated at a timing when a predetermined value is reached (see, for example, Patent Document 1). Therefore, in a charging circuit that charges the power storage device, it is required to accurately measure the charging current. In order to measure the charging current, a potential difference between both ends of a circuit element (for example, a circuit element such as a field effect transistor or a resistor) arranged on the power supply line through which the charging current flows is measured. If the resistance value and voltage-current characteristics of this circuit element are known in advance, the magnitude of the current flowing through the circuit element (that is, the charging current) can be measured using the measured voltage value.

米国特許第５９０５３６２号明細書US Pat. No. 5,905,362

上述したように、充電回路では充電電流を精度よく測定する必要がある。そのためには、充電電流の測定に用いる回路要素の抵抗値をある程度大きくすることが要請される。抵抗値が小さいと、特に充電電流が小さい時には回路要素の両端の電位差が小さくなり、高い精度での測定が難しくなるためである。しかしながら、充電電流が流れる電力供給線上に配置される回路要素の抵抗値を大きくすることは、ジュール熱の発生によるエネルギーの損失につながる。すなわち、充電電流の測定精度向上と、充電回路中におけるエネルギー損失低減とは、両立させることが困難な関係にある。   As described above, it is necessary to accurately measure the charging current in the charging circuit. For this purpose, it is required to increase the resistance value of the circuit element used for measuring the charging current to some extent. This is because, when the resistance value is small, the potential difference between both ends of the circuit element is small, particularly when the charging current is small, and measurement with high accuracy becomes difficult. However, increasing the resistance value of the circuit element arranged on the power supply line through which the charging current flows leads to energy loss due to generation of Joule heat. That is, there is a difficult relationship between improving the measurement accuracy of the charging current and reducing the energy loss in the charging circuit.

本発明は上記実情を考慮してなされたものであって、その目的の一つは、比較的エネルギー損失が少なく、かつ、実用上十分な精度で充電電流の大きさを測定できる充電回路及び充電方法を提供することにある。   The present invention has been made in consideration of the above circumstances, and one of its purposes is a charging circuit and a charging circuit that can measure the magnitude of the charging current with relatively little energy loss and sufficient practical accuracy. It is to provide a method.

本発明に係る充電回路は、電力供給源が出力する電力を蓄電装置に供給する第１及び第２の電力供給線と、前記第１及び第２の電力供給線それぞれを流れる電流を測定する電流測定手段と、前記測定される電流に基づいて、前記蓄電装置への電力供給を制御する制御手段と、を含み、前記第１の電力供給線は、第１の回路要素を備え、前記第２の電力供給線は、前記第１の回路要素よりも大きな抵抗値を持つ第２の回路要素を備え、前記電流測定手段は、前記第１の回路要素の両端の電位差を測定することにより、前記第１の電力供給線を流れる電流を測定し、前記第２の回路要素の両端の電位差を測定することにより、前記第第２の電力供給線を流れる電流を測定し、前記制御手段は、前記測定される前記第１の電力供給線を流れる電流の値に応じて、前記蓄電装置への電力供給に用いる電力供給線を前記第１の電力供給線から前記第２の電力供給線に切り替えることを特徴とする。   The charging circuit according to the present invention includes first and second power supply lines that supply power output from a power supply source to a power storage device, and currents that measure currents flowing through the first and second power supply lines, respectively. Measuring means and control means for controlling power supply to the power storage device based on the measured current, the first power supply line comprising a first circuit element, and the second power supply line. The power supply line includes a second circuit element having a resistance value larger than that of the first circuit element, and the current measuring unit measures the potential difference between both ends of the first circuit element, thereby The current flowing through the first power supply line is measured, and the current flowing through the second power supply line is measured by measuring the potential difference between both ends of the second circuit element. Of the current flowing through the first power supply line to be measured Depending on, and switches on the second power supply line to power supply line used for power supply to the power storage device from the first power supply line.

また、本発明に係る充電方法は、電力供給源が出力する電力を蓄電装置に供給する電力供給線として、第１の回路要素を備える第１の電力供給線と、前記第１の回路要素よりも大きな抵抗値を持つ第２の回路要素を備える第２の電力供給線と、を含む充電回路を用いた充電方法であって、前記第１の回路要素の両端の電位差を測定することにより、前記第１の電力供給線を流れる電流を測定するステップと、前記測定される前記第１の電力供給線を流れる電流に基づいて、前記蓄電装置への電力供給を制御するステップと、前記測定される前記第１の電力供給線を流れる電流の値に応じて、前記蓄電装置への電力供給に用いる電力供給線を前記第１の電力供給線から前記第２の電力供給線に切り替えるステップと、前記第２の回路要素の両端の電位差を測定することにより、前記第２の電力供給線を流れる電流を測定するステップと、前記測定される前記第２の電力供給線を流れる電流に基づいて、前記蓄電装置への電力供給を制御するステップと、を含むことを特徴とする。   In addition, the charging method according to the present invention includes a first power supply line including a first circuit element as a power supply line for supplying power output from the power supply source to the power storage device, and the first circuit element. A charging method using a charging circuit including a second power supply line including a second circuit element having a large resistance value by measuring a potential difference between both ends of the first circuit element, Measuring the current flowing through the first power supply line; controlling the power supply to the power storage device based on the measured current flowing through the first power supply line; Switching the power supply line used for power supply to the power storage device from the first power supply line to the second power supply line according to the value of the current flowing through the first power supply line. Both ends of the second circuit element By measuring the potential difference, the step of measuring the current flowing through the second power supply line and controlling the power supply to the power storage device based on the measured current flowing through the second power supply line And a step of performing.

本発明の実施の形態に係る充電回路の概略の回路構成図である。1 is a schematic circuit configuration diagram of a charging circuit according to an embodiment of the present invention. 本発明の実施の形態に係る充電回路が実行する充電制御の流れの一例を示すフロー図である。It is a flowchart which shows an example of the flow of the charge control which the charging circuit which concerns on embodiment of this invention performs. 本発明の実施の形態に係る充電回路を用いた場合の充電電流、電圧、及び電力供給線上における単位時間あたりのエネルギー損失の時間変化の一例を示す図である。It is a figure which shows an example of the time change of the energy loss per unit time on the charging current, voltage, and electric power supply line at the time of using the charging circuit which concerns on embodiment of this invention.

以下、本発明の実施の形態について、図面に基づき詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

図１は、本発明の一実施形態に係る充電回路１を備える電子機器の、概略の回路構成を示す構成図である。本実施形態に係る充電回路１は、充電用ＩＣ１１と、インダクタ１２と、コンデンサ１３と、抵抗器１４と、を含んで構成される。さらに、充電用ＩＣ１１は、スイッチング素子として機能する電界効果トランジスタ（ＦＥＴ）１５ａ、１５ｂ、１５ｃ、及び１５ｄと、制御部１６と、を含んで構成されている。また、充電回路１には電源２、負荷３及び二次電池４が接続されている。   FIG. 1 is a configuration diagram showing a schematic circuit configuration of an electronic apparatus including a charging circuit 1 according to an embodiment of the present invention. The charging circuit 1 according to the present embodiment includes a charging IC 11, an inductor 12, a capacitor 13, and a resistor 14. Further, the charging IC 11 includes field effect transistors (FETs) 15 a, 15 b, 15 c, and 15 d that function as switching elements, and a control unit 16. A power source 2, a load 3 and a secondary battery 4 are connected to the charging circuit 1.

本実施形態に係る充電回路１は、電源２が出力する電力を負荷３及び二次電池４の一方又は両方に対して供給することによって、負荷３を駆動させたり、二次電池４を充電したりする。また、充電回路１は、必要に応じて、二次電池４に蓄積された電力を負荷３に供給してもよい。ここで、電源２は直流電力を供給する電力供給源であって、例えば商用の交流電源から供給される電力を直流電力に変換する電源回路であってもよいし、外部のＵＳＢホスト機器からＵＳＢケーブルを介して供給される直流電力を受け入れて出力するＵＳＢ電源回路であってもよい。また、負荷３は、例えば電子機器のシステム回路等、電力供給を必要とする各種のデバイスであってよい。二次電池４は、リチウムイオン二次電池等の繰り返し充放電が可能な電池であって、本実施形態において蓄電装置として機能する。   The charging circuit 1 according to this embodiment drives the load 3 or charges the secondary battery 4 by supplying the power output from the power source 2 to one or both of the load 3 and the secondary battery 4. Or Further, the charging circuit 1 may supply the power stored in the secondary battery 4 to the load 3 as necessary. Here, the power source 2 is a power supply source that supplies DC power, and may be, for example, a power supply circuit that converts power supplied from a commercial AC power source into DC power, or from an external USB host device to a USB. It may be a USB power supply circuit that receives and outputs DC power supplied via a cable. The load 3 may be various devices that require power supply, such as a system circuit of an electronic device. The secondary battery 4 is a battery that can be repeatedly charged and discharged, such as a lithium ion secondary battery, and functions as a power storage device in the present embodiment.

充電用ＩＣ１１は、外部との接続端子として、接続端子Ｔ１〜Ｔ８を備えている。そして、接続端子Ｔ１には電源２の出力が接続されている。充電用ＩＣ１１の内部において、接続端子Ｔ１と接続端子Ｔ２との間にはＦＥＴ１５ａが接続されており、ＦＥＴ１５ａの接続端子Ｔ２側の一端にはＦＥＴ１５ｂの一端が接続されている。また、ＦＥＴ１５ｂの他端は接地されている。一方、充電用ＩＣ１１の外部で、接続端子Ｔ２と接続端子Ｔ３との間にはインダクタ１２が接続されている。接続端子Ｔ３にはさらにコンデンサ１３の一端が接続されており、コンデンサ１３の他端は接地されている。   The charging IC 11 includes connection terminals T1 to T8 as connection terminals with the outside. The output of the power source 2 is connected to the connection terminal T1. In the charging IC 11, an FET 15a is connected between the connection terminal T1 and the connection terminal T2, and one end of the FET 15b is connected to one end of the FET 15a on the connection terminal T2 side. The other end of the FET 15b is grounded. On the other hand, outside the charging IC 11, an inductor 12 is connected between the connection terminal T2 and the connection terminal T3. One end of a capacitor 13 is further connected to the connection terminal T3, and the other end of the capacitor 13 is grounded.

ＦＥＴ１５ａ、ＦＥＴ１５ｂ、インダクタ１２、コンデンサ１３及び制御部１６は、全体としてＤＣ／ＤＣコンバータを構成している。すなわち、制御部１６がＦＥＴ１５ａ及び１５ｂのオン／オフを周期的に切り替える制御を実行し、インダクタ１２及びコンデンサ１３が充電用ＩＣ１１の接続端子Ｔ２から出力される電圧を平滑化することによって、電源２から入力される電圧が目標電圧に変換される。ここで、目標電圧はＤＣ／ＤＣコンバータの出力電圧の目標値であって、二次電池４の充電状態等に応じて制御部１６によって決定される。   The FET 15a, FET 15b, the inductor 12, the capacitor 13, and the control unit 16 constitute a DC / DC converter as a whole. That is, the control unit 16 performs control to periodically turn on / off the FETs 15a and 15b, and the inductor 12 and the capacitor 13 smooth the voltage output from the connection terminal T2 of the charging IC 11, thereby allowing the power source 2 Is input to a target voltage. Here, the target voltage is a target value of the output voltage of the DC / DC converter, and is determined by the control unit 16 according to the state of charge of the secondary battery 4 and the like.

充電用ＩＣ１１の内部で接続端子Ｔ３は接続端子Ｔ４と接続されており、充電用ＩＣ１１外部において接続端子Ｔ４には負荷３が接続されている。これにより、ＤＣ／ＤＣコンバータによって目標電圧に変換された電源電圧は、接続端子Ｔ３から再び充電用ＩＣ１１内に入力され、接続端子Ｔ４経由で負荷３に供給される。   The connection terminal T3 is connected to the connection terminal T4 inside the charging IC 11, and the load 3 is connected to the connection terminal T4 outside the charging IC 11. As a result, the power supply voltage converted into the target voltage by the DC / DC converter is input again from the connection terminal T3 into the charging IC 11 and supplied to the load 3 via the connection terminal T4.

さらに、充電用ＩＣ１１内において、接続端子Ｔ３及び接続端子Ｔ４には、第１電力供給線１７及び第２電力供給線１８それぞれの一端が接続されている。また、第１電力供給線１７及び第２電力供給線１８それぞれの他端は、二次電池４の一端に接続されている。すなわち、第１電力供給線１７と第２電力供給線１８とは、ＤＣ／ＤＣコンバータと二次電池４との間で互いに並列に接続されている。電源２が出力し、ＤＣ／ＤＣコンバータによって目標電圧に変換された電力は、接続端子Ｔ３から充電用ＩＣ１１内に再び入力され、第１電力供給線１７及び第２電力供給線１８のいずれかを経由して、二次電池４に供給される。   Further, in the charging IC 11, one end of each of the first power supply line 17 and the second power supply line 18 is connected to the connection terminal T3 and the connection terminal T4. The other ends of the first power supply line 17 and the second power supply line 18 are connected to one end of the secondary battery 4. That is, the first power supply line 17 and the second power supply line 18 are connected in parallel to each other between the DC / DC converter and the secondary battery 4. The power output from the power source 2 and converted into the target voltage by the DC / DC converter is input again into the charging IC 11 from the connection terminal T3, and either the first power supply line 17 or the second power supply line 18 is connected. It is supplied to the secondary battery 4 via.

具体的に、第１電力供給線１７は、ＦＥＴ１５ｃを含んで構成されている。充電用ＩＣ１１内においてＦＥＴ１５ｃの一端は接続端子Ｔ３及びＴ４に、他端は接続端子Ｔ８に、それぞれ接続されおり、接続端子Ｔ８には充電用ＩＣ１１の外部において二次電池４の一端が接続されている。また、二次電池４の他端は接地されている。本実施形態では、ＦＥＴ１５ｃが第１の回路要素として機能する。なお、以下ではＦＥＴ１５ｃの抵抗値をＲ１とする。このＲ１の値は、例えば約２０ｍΩであってよい。   Specifically, the first power supply line 17 includes an FET 15c. In the charging IC 11, one end of the FET 15 c is connected to the connection terminals T 3 and T 4, and the other end is connected to the connection terminal T 8. One end of the secondary battery 4 is connected to the connection terminal T 8 outside the charging IC 11. Yes. The other end of the secondary battery 4 is grounded. In the present embodiment, the FET 15c functions as a first circuit element. Hereinafter, the resistance value of the FET 15c is R1. The value of R1 may be about 20 mΩ, for example.

また、第２電力供給線１８は、互いに直列に接続されたＦＥＴ１５ｄ及び抵抗器１４を含んで構成されている。充電用ＩＣ１１内においてＦＥＴ１５ｄの一端が接続端子Ｔ３及びＴ４に、他端が接続端子Ｔ５に、それぞれ接続されている。また、充電用ＩＣ１１の外部において抵抗器１４の一端は接続端子Ｔ５及びＴ６に、抵抗器１４の他端は接続端子Ｔ７及びＴ８に、それぞれ接続されている。さらに、抵抗器１４の他端は、二次電池４の一端にも接続されている。本実施形態では、抵抗器１４が第２の回路要素として機能する。なお、以下ではＦＥＴ１５ｄの抵抗値をＲ２とし、抵抗器１４の抵抗値をＲ３とする。Ｒ２の値は、例えば約１００ｍΩであってよい。また、Ｒ３の値は、第１電力供給線１７上に配置されたＦＥＴ１５ｃの抵抗値Ｒ１よりも大きくなっており、例えば１００ｍΩ（±１％）であってよい。   The second power supply line 18 includes a FET 15d and a resistor 14 connected in series with each other. In the charging IC 11, one end of the FET 15d is connected to the connection terminals T3 and T4, and the other end is connected to the connection terminal T5. Further, outside the charging IC 11, one end of the resistor 14 is connected to the connection terminals T5 and T6, and the other end of the resistor 14 is connected to the connection terminals T7 and T8. Further, the other end of the resistor 14 is also connected to one end of the secondary battery 4. In the present embodiment, the resistor 14 functions as a second circuit element. In the following, the resistance value of the FET 15d is R2, and the resistance value of the resistor 14 is R3. The value of R2 may be about 100 mΩ, for example. The value of R3 is larger than the resistance value R1 of the FET 15c arranged on the first power supply line 17, and may be 100 mΩ (± 1%), for example.

制御部１６は、本実施形態に係る充電回路１全体の制御を行う。充電用ＩＣ１１内において、制御部１６は接続端子Ｔ２，Ｔ３，Ｔ６，及びＴ７のそれぞれと接続されており、これらの各端子における電圧（以下、それぞれＶｔ２，Ｖｔ３，Ｖｔ６及びＶｔ７と表記する）を測定可能になっている。また、制御部１６は、ＦＥＴ１５ｃの両端とも接続されており、ＦＥＴ１５ｃ両端それぞれの電圧（以下、Ｖｆ１及びＶｆ２と表記する）を測定可能になっている。なお、接続端子Ｔ７の電圧Ｖｔ７は、二次電池４の電圧Ｖｂに相当する。また、制御部１６はＦＥＴ１５ａ〜１５ｄのゲート電極と接続されており、各ＦＥＴのオン／オフを切り替え可能になっている。これにより、制御部１６は、測定した各端子の電圧に応じて各ＦＥＴの切り替え制御を行うことで、二次電池４への電力供給を制御する。   The control unit 16 controls the entire charging circuit 1 according to the present embodiment. In the charging IC 11, the control unit 16 is connected to each of the connection terminals T2, T3, T6, and T7, and voltages at these terminals (hereinafter referred to as Vt2, Vt3, Vt6, and Vt7, respectively). Measurement is possible. The control unit 16 is also connected to both ends of the FET 15c, and can measure the voltages at the both ends of the FET 15c (hereinafter referred to as Vf1 and Vf2). The voltage Vt7 at the connection terminal T7 corresponds to the voltage Vb of the secondary battery 4. The control unit 16 is connected to the gate electrodes of the FETs 15a to 15d, and can turn on / off each FET. Thereby, the control part 16 controls the electric power supply to the secondary battery 4 by performing switching control of each FET according to the measured voltage of each terminal.

具体的に制御部１６は、二次電池４の充電を行う際には、ＦＥＴ１５ｃ及び１５ｄのオン／オフを切り替えることによって、第１電力供給線１７及び第２電力供給線１８のいずれか一方を選択的に導通させ、他方を切断する。これにより、第１電力供給線１７及び第２電力供給線１８のいずれかを経由して、二次電池４の充電が行われる。さらに制御部１６は、第１電力供給線１７及び第２電力供給線１８のそれぞれを流れる電流を測定し、当該測定される電流の大きさに基づいてＤＣ／ＤＣコンバータの目標電圧を調整することにより、二次電池４への電力供給を制御する。一例として、本実施形態に係る充電回路１は、充電開始時には充電電流Ｉｂが予め定められた目標電流値Ｉｏに維持されるように定電流充電を実行し、二次電池４の電圧Ｖｂが予め定められた満充電電圧Ｖｍに到達した後は、充電電流Ｉｂの大きさが予め定められた終了判定値Ｉｍに低下するまでの間、定電圧充電を行う。   Specifically, when charging the secondary battery 4, the control unit 16 switches one of the first power supply line 17 and the second power supply line 18 by switching on and off the FETs 15 c and 15 d. Selectively conduct and disconnect the other. Thereby, the secondary battery 4 is charged via either the first power supply line 17 or the second power supply line 18. Further, the control unit 16 measures the current flowing through each of the first power supply line 17 and the second power supply line 18 and adjusts the target voltage of the DC / DC converter based on the magnitude of the measured current. Thus, power supply to the secondary battery 4 is controlled. As an example, the charging circuit 1 according to the present embodiment performs constant current charging so that the charging current Ib is maintained at a predetermined target current value Io at the start of charging, and the voltage Vb of the secondary battery 4 is set in advance. After reaching the predetermined full charge voltage Vm, constant voltage charging is performed until the magnitude of the charging current Ib decreases to a predetermined end determination value Im.

ここで、制御部１６が第１電力供給線１７及び第２電力供給線１８それぞれを流れる電流の大きさを測定する方法について、説明する。制御部１６は、第１電力供給線１７及び第２電力供給線１８のそれぞれが備える回路要素の両端の電位差を測定することによって、第１電力供給線１７及び第２電力供給線１８それぞれを流れる電流を測定する。   Here, a method in which the control unit 16 measures the magnitude of the current flowing through each of the first power supply line 17 and the second power supply line 18 will be described. The control unit 16 measures the potential difference between both ends of the circuit elements included in each of the first power supply line 17 and the second power supply line 18, thereby flowing through each of the first power supply line 17 and the second power supply line 18. Measure the current.

具体的に、制御部１６は、ＦＥＴ１５ｃ両端それぞれの電圧Ｖｆ１及びＶｆ２を測定することによって、第１の回路要素であるＦＥＴ１５ｃの両端の電位差（Ｖｆ１−Ｖｆ２）を算出する。ＦＥＴ１５ｃの両端の電位差（Ｖｆ１−Ｖｆ２）が分かれば、制御部１６は、予めその内部に格納されたＦＥＴ１５ｃの電圧−電流特性に関する情報を利用して、当該電位差を生じさせるような電流値を算出できる。この電流値が、第１電力供給線１７を流れて二次電池４に入力される充電電流Ｉｂ１の大きさとなる。   Specifically, the control unit 16 measures the voltages Vf1 and Vf2 at both ends of the FET 15c, thereby calculating a potential difference (Vf1-Vf2) at both ends of the FET 15c, which is the first circuit element. If the potential difference (Vf1-Vf2) between both ends of the FET 15c is known, the control unit 16 uses the information on the voltage-current characteristics of the FET 15c stored in advance to calculate a current value that causes the potential difference. it can. This current value becomes the magnitude of the charging current Ib1 that flows through the first power supply line 17 and is input to the secondary battery 4.

また、制御部１６は、接続端子Ｔ６及びＴ７それぞれの電圧Ｖｔ６及びＶｔ７を測定することによって、第２の回路要素である抵抗器１４の両端の電位差（Ｖｔ６−Ｖｔ７）を算出する。抵抗器１４の両端の電位差（Ｖｔ６−Ｖｔ７）が分かれば、制御部１６は、予めその内部に格納された抵抗器１４の抵抗値Ｒ３を用いて、オームの法則により当該電位差を生じさせる電流値を（Ｖｔ６−Ｖｔ７）／Ｒ３と算出できる。この電流値が、第２電力供給線１８を流れて二次電池４に入力される充電電流Ｉｂ２の大きさとなる。   In addition, the control unit 16 measures the voltages Vt6 and Vt7 of the connection terminals T6 and T7, thereby calculating the potential difference (Vt6−Vt7) across the resistor 14 which is the second circuit element. If the potential difference (Vt6−Vt7) between both ends of the resistor 14 is known, the control unit 16 uses the resistance value R3 of the resistor 14 stored therein in advance to generate a current value that causes the potential difference according to Ohm's law. Can be calculated as (Vt6-Vt7) / R3. This current value becomes the magnitude of the charging current Ib2 that flows through the second power supply line 18 and is input to the secondary battery 4.

以下、本実施形態において制御部１６が実行する充電制御の具体例について、図２のフロー図を用いて説明する。   Hereinafter, a specific example of the charging control executed by the control unit 16 in the present embodiment will be described with reference to the flowchart of FIG.

まず、充電開始時には、制御部１６はＦＥＴ１５ｃをオンにし、ＦＥＴ１５ｄをオフにすることによって、充電経路を第１電力供給線１７に切り替える（Ｓ１）。これにより、第１電力供給線１７経由で二次電池４の充電が開始される。この状態において、制御部１６は、第１電力供給線１７を流れる充電電流Ｉｂ１の測定を継続的に繰り返して、充電電流Ｉｂ１の監視を行う。さらに制御部１６は、当該測定される充電電流Ｉｂ１の値が予め定められた目標電流値Ｉｏに一致するようにＤＣ／ＤＣコンバータを制御して、定電流充電を行う（Ｓ２）。その後、二次電池４の電圧Ｖｂが満充電電圧Ｖｍに到達すると（Ｓ３）、制御部１６はＤＣ／ＤＣコンバータを制御して定電圧充電を行う（Ｓ４）。この段階では、二次電池４の充電が進行するにつれて、二次電池４に流れる充電電流Ｉｂ１は低下していくことになる。   First, at the start of charging, the controller 16 switches the charging path to the first power supply line 17 by turning on the FET 15c and turning off the FET 15d (S1). Thereby, charging of the secondary battery 4 is started via the first power supply line 17. In this state, the control unit 16 continuously repeats the measurement of the charging current Ib1 flowing through the first power supply line 17 to monitor the charging current Ib1. Furthermore, the control unit 16 performs constant current charging by controlling the DC / DC converter so that the measured value of the charging current Ib1 coincides with a predetermined target current value Io (S2). Thereafter, when the voltage Vb of the secondary battery 4 reaches the full charge voltage Vm (S3), the control unit 16 controls the DC / DC converter to perform constant voltage charging (S4). At this stage, as the charging of the secondary battery 4 proceeds, the charging current Ib1 flowing through the secondary battery 4 decreases.

その後、制御部１６は、測定される充電電流Ｉｂ１の値に応じて、二次電池４の充電に用いる電力供給線を第１電力供給線１７から第２電力供給線１８に切り替える。具体的に、測定される充電電流Ｉｂ１の値が予め定められた閾値Ｉｔｈ（例えば２００ｍＡ）を下回ると（Ｓ５）、制御部１６はＦＥＴ１５ｃをオフに、ＦＥＴ１５ｄをオンに、それぞれ切り替えることによって、第１電力供給線１７を切断し、第２電力供給線１８を導通させる。これにより、充電経路が第２電力供給線１８に切り替えられ（Ｓ６）、以降は第２電力供給線１８経由で二次電池４の定電圧充電が行われる（Ｓ７）。   Thereafter, the control unit 16 switches the power supply line used for charging the secondary battery 4 from the first power supply line 17 to the second power supply line 18 according to the measured value of the charging current Ib1. Specifically, when the value of the measured charging current Ib1 falls below a predetermined threshold value Ith (for example, 200 mA) (S5), the control unit 16 switches the FET 15c off and the FET 15d on, thereby switching the first The first power supply line 17 is disconnected and the second power supply line 18 is made conductive. As a result, the charging path is switched to the second power supply line 18 (S6), and thereafter, the secondary battery 4 is charged at a constant voltage via the second power supply line 18 (S7).

この状態で、制御部１６は第２電力供給線１８を流れる充電電流Ｉｂ２の測定を繰り返して、充電電流Ｉｂ２の監視を行う。そして、測定される充電電流Ｉｂ２の値が終了判定値Ｉｍに到達すると（Ｓ８）、制御部１６は二次電池４が満充電になったと判定する。二次電池４が満充電になったと判定されると、制御部１６は、ＦＥＴ１５ｃ及び１５ｄの両方をオフに切り替えて、二次電池４に対する電力の供給を停止する（Ｓ９）。これにより、二次電池４の充電は終了する。   In this state, the control unit 16 repeatedly measures the charging current Ib2 flowing through the second power supply line 18 and monitors the charging current Ib2. When the measured value of the charging current Ib2 reaches the end determination value Im (S8), the control unit 16 determines that the secondary battery 4 is fully charged. When it is determined that the secondary battery 4 is fully charged, the control unit 16 switches off both the FETs 15c and 15d and stops supplying power to the secondary battery 4 (S9). Thereby, charge of the secondary battery 4 is complete | finished.

このような制御によれば、充電電流Ｉｂの値が大きい間は、経路上の抵抗値が比較的小さな第１電力供給線１７を経由して充電が行われるため、抵抗値が大きな充電経路を経由して充電を行う場合と比較して、充電経路上でのエネルギー損失を低く抑えることができる。一方、充電電流Ｉｂの値が閾値Ｉｔｈを下回ると、経路上の抵抗値が比較的大きな第２電力供給線１８を経由して充電が行われることになるが、このときは既に充電電流Ｉｂの値が十分小さくなっているので、抵抗値が大きいにも関わらず、熱の発生によって生じるエネルギー損失は比較的大きくならない。   According to such control, while the value of the charging current Ib is large, charging is performed via the first power supply line 17 whose resistance value on the path is relatively small. Compared with the case where charging is performed via, energy loss on the charging path can be kept low. On the other hand, when the value of the charging current Ib falls below the threshold value Ith, charging is performed via the second power supply line 18 having a relatively large resistance value on the path. Since the value is sufficiently small, the energy loss caused by the generation of heat does not become relatively large despite the large resistance value.

さらに、本実施形態に係る充電回路１によれば、第２電力供給線１８経由で充電を行っている間は、ＦＥＴ１５ａと比較して抵抗値の大きな抵抗器１４の両端の電位差を測定することによって、充電電流Ｉｂ２の測定が行われる。一般に、充電電流Ｉｂの絶対値が大きい間は、抵抗値が比較的小さな回路要素であっても、その両端の電位差はある程度大きくなるので、十分な精度で充電電流Ｉｂを測定できる。ところが、充電電流Ｉｂの絶対値が小さくなると、抵抗値の小さな回路要素の両端の電位差は小さくなってしまうため、このような回路要素を用いて精度よく充電電流Ｉｂを測定することは困難になる。だが、本実施形態では、充電電流Ｉｂの絶対値が比較的小さくなったときには、抵抗値が比較的大きな回路要素（すなわち、抵抗器１４）を備えた第２電力供給線１８に充電経路を切り替え、抵抗器１４の両端の電位差を用いて充電電流Ｉｂを測定する。そのため、充電開始から終了までの全期間にわたって、実用上十分な精度で充電電流Ｉｂを測定することができる。   Furthermore, according to the charging circuit 1 according to the present embodiment, while charging is performed via the second power supply line 18, the potential difference between both ends of the resistor 14 having a large resistance value compared to the FET 15a is measured. Thus, the charging current Ib2 is measured. In general, while the absolute value of the charging current Ib is large, the potential difference between both ends of the circuit element having a relatively small resistance value increases to some extent, so that the charging current Ib can be measured with sufficient accuracy. However, if the absolute value of the charging current Ib is reduced, the potential difference between both ends of the circuit element having a small resistance value is reduced. Therefore, it is difficult to accurately measure the charging current Ib using such a circuit element. . However, in the present embodiment, when the absolute value of the charging current Ib becomes relatively small, the charging path is switched to the second power supply line 18 having a circuit element having a relatively large resistance value (that is, the resistor 14). Then, the charging current Ib is measured using the potential difference between both ends of the resistor 14. Therefore, the charging current Ib can be measured with sufficient practical accuracy over the entire period from the start to the end of charging.

なお、二次電池４が満充電になったか否かは、充電電流Ｉｂが終了判定値Ｉｍまで低下したか否かで判定される。そのため、特に終了判定値Ｉｍ付近では、精度よく充電電流Ｉｂを測定する必要がある。そこで本実施形態において、制御部１６は、必ず第２電力供給線１８への充電経路切り替えを行って、測定された充電電流Ｉｂ２の値が終了判定値Ｉｍになったと判定された場合に、充電を終了することとしてもよい。すなわち、仮に第１電力供給線１７経由で充電を行っている間に、急激に充電電流Ｉｂ１が低下して、その値が終了判定値Ｉｍまで下がったとしても、その時点で充電を終了するのではなく、第２電力供給線１８への充電経路切り替えを行って、抵抗器１４の両端の電位差を用いて充電電流Ｉｂ２の値を測定する。そして、測定された充電電流Ｉｂ２の値が終了判定値Ｉｍまで低下していることを確認してから、充電を終了する。こうすれば、高い精度で充電終了の判定を行うことができる。   Whether or not the secondary battery 4 is fully charged is determined by whether or not the charging current Ib has decreased to the end determination value Im. Therefore, it is necessary to measure the charging current Ib with high accuracy, particularly in the vicinity of the end determination value Im. Therefore, in the present embodiment, the control unit 16 always switches the charging path to the second power supply line 18, and when it is determined that the measured value of the charging current Ib <b> 2 has reached the end determination value Im, the charging is performed. May be terminated. That is, even if the charging current Ib1 suddenly decreases while the charging is being performed via the first power supply line 17, and the value drops to the termination determination value Im, the charging is terminated at that time. Instead, the charging path to the second power supply line 18 is switched, and the value of the charging current Ib2 is measured using the potential difference between both ends of the resistor 14. Then, after confirming that the measured value of the charging current Ib2 has decreased to the termination determination value Im, the charging is terminated. In this way, the end of charging can be determined with high accuracy.

図３は、以上説明したような充電制御が行われる場合の、二次電池４に流れる充電電流Ｉｂ、二次電池４の電圧Ｖｂ、及び充電経路上における単位時間あたりのエネルギー損失Ｐの時間変化を示すグラフである。なお、この図においては、実線が本実施形態に係る充電回路１における充電電流Ｉｂ（単位：Ａ）、二次電池４の電圧Ｖｂ（単位：Ｖ）及びエネルギー損失Ｐ１（単位：Ｗ）の時間変化をそれぞれ示している。また、グラフ中の破線は、比較例として、ＬＤＯ（Low Drop Out）レギュレータを用いた充電回路のエネルギー損失Ｐ２の時間変化を示している。この比較例の充電回路は、本実施形態に係る充電回路１に対して、第２電力供給線１８が存在せず、かつ、ＦＥＴ１５ｃと対応する位置にＬＤＯ（Low Drop Out）レギュレータとして用いられるＦＥＴを配置した充電回路である。また、図３のグラフにおいて時刻ｔ０は充電開始のタイミングを、時刻ｔ１は定電圧充電が開始されて充電電流Ｉｂが低下し始めるタイミングを、時刻ｔ２は充電電流Ｉｂが閾値Ｉｔｈまで低下して第１電力供給線１７から第２電力供給線１８への充電経路切り替えが実行されるタイミングを、時刻ｔ３は充電電流Ｉｂが終了判定値Ｉｍまで低下して充電が終了するタイミングを、それぞれ示している。この図に示されるように、本実施形態に係る充電回路１を用いた場合のエネルギー損失は、比較例に対して一貫して小さくなっている。   FIG. 3 shows the time change of the charging current Ib flowing through the secondary battery 4, the voltage Vb of the secondary battery 4, and the energy loss P per unit time on the charging path when the charging control as described above is performed. It is a graph which shows. In this figure, the solid lines indicate the charging current Ib (unit: A), the voltage Vb (unit: V) of the secondary battery 4 and the energy loss P1 (unit: W) in the charging circuit 1 according to this embodiment. Each change is shown. Moreover, the broken line in a graph has shown the time change of the energy loss P2 of the charging circuit using a LDO (Low Drop Out) regulator as a comparative example. The charging circuit of this comparative example is different from the charging circuit 1 according to the present embodiment in that the second power supply line 18 does not exist and an FET used as an LDO (Low Drop Out) regulator at a position corresponding to the FET 15c. Is a charging circuit. Further, in the graph of FIG. 3, time t0 indicates the timing of starting charging, time t1 indicates the timing when constant voltage charging starts and charging current Ib starts to decrease, and time t2 indicates that charging current Ib decreases to threshold value Ith. The timing at which the charging path switching from the first power supply line 17 to the second power supply line 18 is executed, and the time t3 indicates the timing at which the charging current Ib decreases to the end determination value Im and the charging ends. . As shown in this figure, the energy loss when the charging circuit 1 according to the present embodiment is used is consistently smaller than that of the comparative example.

具体例として、ＬＤＯレギュレータを用いた充電回路において、充電電流Ｉｂ＝１０００ｍＡ、入出力電位差ＶＬＤＯ＝２５０ｍＶの場合、エネルギー損失は
Ｐ＝Ｉｂ・ＶＬＤＯ＝１０００ｍＡ×２５０ｍＶ＝２５０ｍＷ
と算出される。一方、本実施形態に係る充電回路１において、充電電流Ｉｂ１＝１０００ｍＡで第１電力供給線１７経由の充電を行っている場合、ＦＥＴ１５ｃの抵抗値Ｒ１＝２０ｍΩとすると、エネルギー損失は
Ｐ＝Ｉ２・Ｒ１＝１０００ｍＡ×１０００ｍＡ×２０ｍΩ＝２０ｍＷ
と算出される。また、充電電流Ｉｂ１が閾値Ｉｔｈまで低下すると、第１電力供給線１７より抵抗値の大きな回路要素を含む第２電力供給線１８へ充電経路が切り替えられるが、このときのエネルギー損失もＬＤＯレギュレータを用いた充電回路におけるエネルギー損失よりも小さくなる。すなわち、ＦＥＴ１５ｄの抵抗値Ｒ２＝１００ｍΩ、抵抗器１４の抵抗値Ｒ３＝１００ｍΩとすると、第２電力供給線１８経由で充電を行う際のエネルギー損失は、充電電流Ｉｂ２＝２００ｍＡのときでも、
Ｐ＝Ｉｂ２２・（Ｒ２＋Ｒ３）＝２００ｍＡ×２００ｍＡ×２００ｍΩ＝８ｍＷ
となる。 As a specific example, in a charging circuit using an LDO regulator, when charging current Ib = 1000 mA and input / output potential difference V LDO = 250 mV, the energy loss is P = Ib · V LDO = 1000 mA × 250 mV = 250 mW.
Is calculated. On the other hand, in the charging circuit 1 according to the present embodiment, when charging is performed via the first power supply line 17 with the charging current Ib1 = 1000 mA, if the resistance value R1 of the FET 15c is 20 mΩ, the energy loss is P = I 2.・ R1 = 1000mA × 1000mA × 20mΩ = 20mW
Is calculated. Further, when the charging current Ib1 decreases to the threshold value Ith, the charging path is switched to the second power supply line 18 including a circuit element having a resistance value larger than that of the first power supply line 17, but the energy loss at this time is also caused by the LDO regulator. It becomes smaller than the energy loss in the used charging circuit. That is, assuming that the resistance value R2 of the FET 15d is 100 mΩ and the resistance value R3 of the resistor 14 is 100 mΩ, the energy loss when charging via the second power supply line 18 is even when the charging current Ib2 is 200 mA.
P = Ib2 2 (R2 + R3) = 200 mA × 200 mA × 200 mΩ = 8 mW
It becomes.

なお、図２のフロー図においては、充電開始時から充電終了時までの間に、一度だけ第１電力供給線１７から第２電力供給線１８への充電経路切り替えが実行されることとしたが、本実施形態における充電制御方法はこのようなものに限られない。例えば、第１電力供給線１７上での充電電流Ｉｂ１の測定精度が十分でなく、実際には充電電流Ｉｂが閾値Ｉｔｈを下回っていないにも関わらず、充電電流Ｉｂ１の測定値が閾値Ｉｔｈ以下と判定されてしまった場合を考える。このような場合、第２電力供給線１８への切り替えが行われた後に、充電電流Ｉｂ２を測定すると、その測定値が閾値Ｉｔｈを超えることがある。そこで、制御部１６は、充電電流Ｉｂ２の測定値が閾値Ｉｔｈを超えている場合には、第２電力供給線１８から第１電力供給線１７への充電経路切り替えを行ってもよい。また、このような充電経路切り替えが頻発することを避けるため、第２電力供給線１８から第１電力供給線１７への切り替えを行うと判断する基準となる充電電流Ｉｂ２の閾値Ｉｔｈ２は、第１電力供給線１７から第２電力供給線１８への切り替えを行うと判断する基準となる充電電流Ｉｂ１の閾値Ｉｔｈと同じ値ではなく、これより大きな値としてもよい。   In the flow chart of FIG. 2, the charging path switching from the first power supply line 17 to the second power supply line 18 is executed only once during the period from the start of charging to the end of charging. The charge control method in this embodiment is not limited to this. For example, the measurement value of the charging current Ib1 on the first power supply line 17 is not sufficient, and the measured value of the charging current Ib1 is less than or equal to the threshold Ith even though the charging current Ib is not actually below the threshold Ith. Consider the case where it has been determined. In such a case, when the charging current Ib2 is measured after switching to the second power supply line 18, the measured value may exceed the threshold value Ith. Therefore, when the measured value of the charging current Ib2 exceeds the threshold value Ith, the control unit 16 may switch the charging path from the second power supply line 18 to the first power supply line 17. Further, in order to avoid frequent switching of the charging path, the threshold Ith2 of the charging current Ib2 serving as a reference for determining that the switching from the second power supply line 18 to the first power supply line 17 is the first The threshold value Ith is not the same as the threshold value Ith of the charging current Ib1 used as a reference for determining that the power supply line 17 is switched to the second power supply line 18, and may be a value larger than this.

また、定電流充電を行う際における目標電流値Ｉｏが、閾値Ｉｔｈを下回る場合には、上述したような電力供給線の切り替え制御を行わずともよい。すなわち、充電対象となる二次電池４の種類等によっては、目標電流値Ｉｏが閾値Ｉｔｈを下回ることもある。このような場合には、充電開始時に、ＦＥＴ１５ｃをオフ、ＦＥＴ１５ｄをオンにして、最初から最後まで第２電力供給線１８経由で二次電池４の充電を行うこととしてもよい。   Further, when the target current value Io when performing constant current charging is lower than the threshold value Ith, the power supply line switching control as described above may not be performed. That is, the target current value Io may fall below the threshold value Ith depending on the type of the secondary battery 4 to be charged. In such a case, at the start of charging, the FET 15c may be turned off and the FET 15d may be turned on, and the secondary battery 4 may be charged via the second power supply line 18 from the beginning to the end.

また、本実施形態に係る充電回路１は、二次電池４から負荷３への電力供給を行ってもよい。具体的に、負荷３が要求する電流が電源２から供給される電流を上回ったときには、ＦＥＴ１５ｃをオンにすることで、第１電力供給線１７を導通させる。これにより、第２電力供給線１８と比較して経路上の抵抗値が小さい第１電力供給線１７を経由して、二次電池４から負荷３へ電流が流れる。このとき負荷３は、電源２及び二次電池４の双方から流れる電流により駆動することになる。   In addition, the charging circuit 1 according to the present embodiment may supply power from the secondary battery 4 to the load 3. Specifically, when the current required by the load 3 exceeds the current supplied from the power supply 2, the first power supply line 17 is made conductive by turning on the FET 15c. As a result, a current flows from the secondary battery 4 to the load 3 via the first power supply line 17 whose resistance value on the path is smaller than that of the second power supply line 18. At this time, the load 3 is driven by a current flowing from both the power source 2 and the secondary battery 4.

また、この状態において負荷３が要求する電流が電源２から供給される電流以下となった場合には、第１電力供給線１７上を流れる電流の向きが反転して、再び第１電力供給線１７を介して二次電池４の充電が行われる。この場合、二次電池４の充電状態や負荷３の動作状況によっては、第１電力供給線１７を経由して流れる充電電流Ｉｂ１の値が閾値Ｉｔｈより小さくなる場合も考えられる。このような場合には、制御部１６は、図２のフローにおけるＳ６の制御と同様にして、第２電力供給線１８への充電経路切り替えを行えばよい。なお、二次電池４の充電が再開された時点における充電電流Ｉｂ１の値が終了判定値Ｉｍより小さな場合であっても、既に述べたように、制御部１６は、直ちに二次電池４の充電を終了するのではなく、第２電力供給線１８への充電経路切り替えを行った上で、充電電流Ｉｂ２の値を測定して充電の終了判定を行うこととしてよい。   In this state, when the current required by the load 3 is equal to or less than the current supplied from the power source 2, the direction of the current flowing on the first power supply line 17 is reversed, and the first power supply line is again displayed. The secondary battery 4 is charged via 17. In this case, depending on the state of charge of the secondary battery 4 and the operating condition of the load 3, the value of the charging current Ib1 flowing through the first power supply line 17 may be smaller than the threshold value Ith. In such a case, the control unit 16 may switch the charging path to the second power supply line 18 in the same manner as the control of S6 in the flow of FIG. Even when the value of the charging current Ib1 at the time when the charging of the secondary battery 4 is resumed is smaller than the end determination value Im, the control unit 16 immediately charges the secondary battery 4 as described above. Instead of ending the charging, the charging path switching to the second power supply line 18 may be performed, and then the charging current Ib2 may be measured to determine the end of charging.

なお、本発明の実施の形態は、以上説明したものに限られない。例えば、以上の説明においては、第１の回路要素としてＦＥＴ１５ｃを、第２の回路要素として抵抗器１４を、それぞれ用いることとしたが、各電力供給線を流れる充電電流Ｉｂの大きさを測定するために用いる回路要素は、これ以外の各種の回路素子や、複数の回路素子を組み合わせてなる回路要素であってもよい。また、本発明の実施の形態に係る充電回路１は、第２の回路要素として、抵抗器１４に代えて、第２電力供給線１８の導通／切断を切り替えるためのＦＥＴ１５ｄそのものを用いてもよい。この場合、第２電力供給線１８上に抵抗器１４は存在せずともよく、制御部１６はＦＥＴ１５ｄの両端の電位差を測定することにより、第２電力供給線１８を流れる充電電流Ｉｂ２の大きさを測定する。ただし、抵抗器は、一般的に、抵抗値の定格値に対するばらつきがＦＥＴより小さい。そのため、第２の回路要素として抵抗器１４を用いることで、ＦＥＴ１５ｃを用いる場合と比較して、より精度よく充電電流Ｉｂ２を測定することができる。   The embodiment of the present invention is not limited to the above-described embodiment. For example, in the above description, the FET 15c is used as the first circuit element and the resistor 14 is used as the second circuit element, but the magnitude of the charging current Ib flowing through each power supply line is measured. The circuit element used for this purpose may be various other circuit elements or a circuit element formed by combining a plurality of circuit elements. Further, the charging circuit 1 according to the embodiment of the present invention may use the FET 15d itself for switching conduction / disconnection of the second power supply line 18 instead of the resistor 14 as the second circuit element. . In this case, the resistor 14 may not be present on the second power supply line 18, and the control unit 16 measures the potential difference between both ends of the FET 15d, whereby the magnitude of the charging current Ib2 flowing through the second power supply line 18 is measured. Measure. However, the resistor generally has a smaller variation of the resistance value with respect to the rated value than the FET. Therefore, by using the resistor 14 as the second circuit element, the charging current Ib2 can be measured with higher accuracy than when the FET 15c is used.

１ 充電回路、２ 電源、３ 負荷、４ 二次電池、１１ 充電用ＩＣ、１２ インダクタ、１３ コンデンサ、１４ 抵抗器、１５ａ〜１５ｄ ＦＥＴ、１６ 制御部、１７ 第１電力供給線、１８ 第２電力供給線。   DESCRIPTION OF SYMBOLS 1 Charging circuit, 2 Power supply, 3 Load, 4 Secondary battery, 11 Charging IC, 12 Inductor, 13 Capacitor, 14 Resistor, 15a-15d FET, 16 Control part, 17 1st power supply line, 18 2nd power Supply line.

Claims (6)

電力供給源が出力する電力を蓄電装置に供給する第１及び第２の電力供給線と、
前記第１及び第２の電力供給線それぞれを流れる電流を測定する電流測定手段と、
前記測定される電流に基づいて、前記蓄電装置への電力供給を制御する制御手段と、
を含み、
前記第１の電力供給線は、第１の回路要素を備え、
前記第２の電力供給線は、前記第１の回路要素よりも大きな抵抗値を持つ第２の回路要素を備え、
前記電流測定手段は、前記第１の回路要素の両端の電位差を測定することにより、前記第１の電力供給線を流れる電流を測定し、前記第２の回路要素の両端の電位差を測定することにより、前記第第２の電力供給線を流れる電流を測定し、
前記制御手段は、前記測定される前記第１の電力供給線を流れる電流の値に応じて、前記蓄電装置への電力供給に用いる電力供給線を前記第１の電力供給線から前記第２の電力供給線に切り替える
ことを特徴とする充電回路。 First and second power supply lines that supply power output from the power supply source to the power storage device;
Current measuring means for measuring a current flowing through each of the first and second power supply lines;
Control means for controlling power supply to the power storage device based on the measured current;
Including
The first power supply line includes a first circuit element;
The second power supply line includes a second circuit element having a larger resistance value than the first circuit element,
The current measuring means measures a current flowing through the first power supply line by measuring a potential difference between both ends of the first circuit element, and measures a potential difference between both ends of the second circuit element. To measure the current flowing through the second power supply line,
The control means determines a power supply line used for power supply to the power storage device from the first power supply line to the second power supply according to the measured value of the current flowing through the first power supply line. A charging circuit characterized by switching to a power supply line. 請求項１記載の充電回路において、
前記制御手段は、
前記第２の電力供給線を用いて前記蓄電装置に電力を供給している間に、前記測定される前記第２の電力供給線を流れる電流の値が予め定められた終了判定値を下回った場合には、前記蓄電装置への電力供給を停止し、
前記第１の電力供給線を用いて前記蓄電装置に電力を供給している間に、前記測定される前記第１の電力供給線を流れる電流の値が前記終了判定値を下回った場合には、前記第２の電力供給線への切り替えを行う
ことを特徴とする充電回路。 The charging circuit according to claim 1,
The control means includes
While supplying power to the power storage device using the second power supply line, the value of the current flowing through the second power supply line to be measured falls below a predetermined end determination value. In the case, the power supply to the power storage device is stopped,
When the measured value of the current flowing through the first power supply line falls below the end determination value while supplying power to the power storage device using the first power supply line The charging circuit is characterized by switching to the second power supply line. 請求項１又は２記載の充電回路において、
前記制御手段は、前記測定される前記第１の電力供給線を流れる電流の値が予め定められた閾値を下回る場合に、前記第１の電力供給線から前記第２の電力供給線への切り替えを行う
ことを特徴とする充電回路。 The charging circuit according to claim 1 or 2,
The control means switches from the first power supply line to the second power supply line when the value of the current flowing through the first power supply line to be measured is lower than a predetermined threshold value. The charging circuit characterized by performing. 請求項３記載の充電回路において、
前記制御手段は、前記測定される前記第２の電力供給線を流れる電流の値が、前記閾値より大きな第２の閾値を上回る場合に、前記蓄電装置への電力供給に用いる電力供給線を前記第２の電力供給線から前記第１の電力供給線に切り替える
ことを特徴とする充電回路。 The charging circuit according to claim 3, wherein
When the value of the current flowing through the second power supply line to be measured exceeds a second threshold value that is larger than the threshold value, the control means uses the power supply line used for power supply to the power storage device. A charging circuit, wherein the second power supply line is switched to the first power supply line. 請求項１から４のいずれか一項記載の充電回路において、
前記第２の回路要素は、抵抗器であって、
前記第２の電力供給線は、当該第２の電力供給線の導通及び切断を切り替えるためのスイッチング素子をさらに含む
ことを特徴とする充電回路。 The charging circuit according to any one of claims 1 to 4,
The second circuit element is a resistor,
The charging circuit, wherein the second power supply line further includes a switching element for switching between conduction and disconnection of the second power supply line. 電力供給源が出力する電力を蓄電装置に供給する電力供給線として、
第１の回路要素を備える第１の電力供給線と、
前記第１の回路要素よりも大きな抵抗値を持つ第２の回路要素を備える第２の電力供給線と、
を含む充電回路を用いた充電方法であって、
前記第１の回路要素の両端の電位差を測定することにより、前記第１の電力供給線を流れる電流を測定するステップと、
前記測定される前記第１の電力供給線を流れる電流に基づいて、前記蓄電装置への電力供給を制御するステップと、
前記測定される前記第１の電力供給線を流れる電流の値に応じて、前記蓄電装置への電力供給に用いる電力供給線を前記第１の電力供給線から前記第２の電力供給線に切り替えるステップと、
前記第２の回路要素の両端の電位差を測定することにより、前記第２の電力供給線を流れる電流を測定するステップと、
前記測定される前記第２の電力供給線を流れる電流に基づいて、前記蓄電装置への電力供給を制御するステップと、
を含むことを特徴とする充電方法。 As a power supply line that supplies power output from the power supply source to the power storage device,
A first power supply line comprising a first circuit element;
A second power supply line comprising a second circuit element having a greater resistance value than the first circuit element;
A charging method using a charging circuit including:
Measuring a current flowing through the first power supply line by measuring a potential difference across the first circuit element;
Controlling power supply to the power storage device based on the measured current flowing through the first power supply line;
A power supply line used for power supply to the power storage device is switched from the first power supply line to the second power supply line in accordance with the value of the current flowing through the first power supply line to be measured. Steps,
Measuring a current flowing through the second power supply line by measuring a potential difference across the second circuit element;
Controlling power supply to the power storage device based on the measured current flowing through the second power supply line;
The charging method characterized by including.
JP2009210685A 2009-09-11 2009-09-11 Charging circuit and method Pending JP2011062022A (en)

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* Cited by examiner, † Cited by third party
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JP2013247745A (en) * 2012-05-24 2013-12-09 Semiconductor Components Industries Llc Charge control circuit and charging circuit

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JP3767024B2 (en) * 1996-07-09 2006-04-19 ソニー株式会社 Charger
JPH10239358A (en) * 1997-02-27 1998-09-11 Sony Corp Current detecting device, current detecting method, and secondary battery device
JP4612174B2 (en) * 2000-11-10 2011-01-12 株式会社東芝 Battery current measurement circuit

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013247745A (en) * 2012-05-24 2013-12-09 Semiconductor Components Industries Llc Charge control circuit and charging circuit
US9035599B2 (en) 2012-05-24 2015-05-19 Semiconductor Components Industries, Llc Charge control circuit, charge circuit, and mobile electronic device

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