JP2006121797A - Charger - Google Patents

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Publication number
JP2006121797A
JP2006121797A JP2004305506A JP2004305506A JP2006121797A JP 2006121797 A JP2006121797 A JP 2006121797A JP 2004305506 A JP2004305506 A JP 2004305506A JP 2004305506 A JP2004305506 A JP 2004305506A JP 2006121797 A JP2006121797 A JP 2006121797A
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JP
Japan
Prior art keywords
charging
voltage
current
charge
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2004305506A
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Japanese (ja)
Inventor
Takuya Ishii
Koichi Mikami
Hiroshi Saito
Akira Watabe
孝一 三上
亮 渡部
卓也 石井
浩 齊藤
Original Assignee
Matsushita Electric Ind Co Ltd
松下電器産業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Matsushita Electric Ind Co Ltd, 松下電器産業株式会社 filed Critical Matsushita Electric Ind Co Ltd
Priority to JP2004305506A priority Critical patent/JP2006121797A/en
Publication of JP2006121797A publication Critical patent/JP2006121797A/en
Application status is Pending legal-status Critical

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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage
    • Y02E60/12Battery technologies with an indirect contribution to GHG emissions mitigation

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit which detects an accurate charge finish current by a boosting charge method for a charger to a lithium ion secondary cell. <P>SOLUTION: This charger is provided with a circuit, where the impedance varies according to the charge current flowing to a secondary cell, as an accurate current detecting circuit. When the charger operates in constant current charge, it varies impedance into low one thereby operating it in high effeiciency. When it operates, with the voltage generated across a detection resistor constant in a voltage detecting circuit, and a charge current drops gradually, the impedance of the accurate current detecting circuit is increased, whereby the voltage drop of a charge current detecting circuit is enlarged more than the voltage drop with only the charge current detecting resistor. The relative error by the voltage of error such as the dispersion of parts to the voltage drop of the charge current detecting circuit is smaller than the relative error by the voltage of error such as the dispersion, etc. of parts to the voltage drop with only the charge current detecting resistor, so this can detect an accurate charge finish current resistant to the dispersion, etc. of parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a charging method suitable for charging a secondary battery such as a lithium ion battery.

  In recent years, when a secondary battery such as a lithium ion battery is rapidly charged, a step-down converter using a switching power supply is frequently used as a means for converting an input power supply voltage from an adapter or the like into a desired voltage. The charger shown in FIG. 6 is a conventional charger (for example, Patent Document 1). Conventional chargers are characterized by easy detection of charging completion and high detection accuracy.

  The operation of the conventional charger will be described below with reference to FIG.

In FIG. 6, reference numeral 1 denotes an AC power source, and the AC input is supplied to the rectifying / smoothing circuit 3 through the input filter 2. After being rectified and smoothed by 3, it is supplied to the primary side of the transformer 4 and switched by the power MOSFET 5. The power MOSFET 5 is driven by being applied to its gate from a PWM (Pulse Wi-dth Modulation) control circuit 6 to perform a switching operation. Thereby, the secondary side output of the transformer 4 is controlled. The transformer 4 generates a predetermined output voltage on the secondary side by switching the primary side by the power MOSFET 5, and the secondary side output is supplied to the rectification / smoothing circuit 7, and is rectified and smoothed to direct current. After that, it is supplied to the secondary battery 9 via the switch unit 8. A charging current detection resistor 10 is inserted on the negative electrode side of the secondary battery 9, and the potential at this point is input to the output control circuit 11 as an output current signal. Further, the voltage (hereinafter referred to as A voltage) on the output side (that is, A in the figure) of the switch unit 8 is input to the output control circuit 11 and the battery voltage detection circuit 12 as an output voltage signal. The battery voltage detection circuit 12 detects the potential on the positive electrode side of the secondary battery 9, determines the end of charging, and controls the charging control circuit 13. The control of the state of charge by the charge control circuit 13 is displayed on the display unit 14. The output control circuit 11 is mainly composed of an error amplifier or the like, compares the rectified and smoothed secondary output voltage and output current with a reference value, and outputs the error output via the photocoupler circuit 15 to the PWM control circuit 6 Is output. As a result, the rectified and smoothed secondary output information is fed back to the primary side of the transformer 4 and PWM controlled, and the voltage generated across the charging current detection resistor 10 and the system in which the charger operates with constant current charging. A system that operates with a constant is obtained.
Japanese Patent No. 3430264

  However, when the charger detects the state of charge, the charging current detection resistor 10 inserted on the negative electrode side of the secondary battery 9 is for improving the efficiency when the charger is operating at constant current charging. In many cases, the charging current is detected using a low-resistance resistor. In this case, when the voltage generated at both ends of the charging current detection resistor 10 operates at a constant voltage, the current flowing through the charging current detection resistor 10 becomes small, and the detected voltage is affected by component variations and the like, and the accuracy is high. It becomes difficult to detect the current.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a suitable secondary battery charger by accurately detecting the charge end current with a simple detection circuit.

  The AC input from the AC power supply is supplied to the rectification / smoothing circuit via the input filter. After being rectified and smoothed, it is supplied to the primary side of the transformer and switched by the power MOSFET. The power MOSFET is driven by being applied to its gate from a PWM (Pulse Wi-dth Modulation) control circuit to perform a switching operation. Thereby, the secondary side output of the transformer 4 is controlled. The transformer generates a predetermined output voltage on the secondary side by switching the primary side with the power MOSFET, and the secondary side output is supplied to the rectification / smoothing circuit, rectified and smoothed to DC The secondary battery is supplied via the switch unit. A high-accuracy charging current detection circuit is inserted on the negative electrode side of the secondary battery, and the potential at this point is input to the output control circuit as an output current signal. The voltage on the output side of the switch unit is input to the output control circuit and the battery voltage detection circuit as an output voltage signal. The battery voltage detection circuit detects the potential on the positive electrode side of the secondary battery, determines the end of charging, and controls the charge control circuit. The control of the state of charge by the charge control circuit is displayed on the display unit. The output control circuit mainly consists of an error amplifier, etc., compares the rectified and smoothed secondary output voltage and output current with the reference value, and the error output is output to the PWM control circuit via the photocoupler circuit. The As a result, the rectified and smoothed secondary side output information is fed back to the primary side of the transformer 4 and PWM controlled, and when charging the secondary battery, the charger operates with constant current charging and constant voltage charging. A system that works with As a high-accuracy charging current detection circuit, a circuit whose impedance varies according to the charging current flowing in the secondary battery is provided, and when the charger operates with constant current charging, it is variable to low impedance, and both ends of the high-accuracy charging current detection circuit When the operating voltage is constant and the charging current gradually decreases, increasing the impedance of the high-accuracy charging current detection circuit reduces the voltage drop of the charging current detection circuit to the voltage of only the charging current detection resistor. Increase against descent.

  According to this configuration, when the charger is operating with constant current charging, the impedance of the charging current detection circuit is small, so that the same efficiency as the charging current detection resistor can be obtained. When the voltage generated at both ends of the detection resistor in the voltage detection circuit operates at a constant voltage, the relative error due to the error voltage due to variations in the parts with respect to the voltage drop of the charge voltage detection circuit by increasing the impedance of the charge current detection circuit is A high-accuracy charging end current that is small compared to the relative error due to the error voltage due to the component variation or the like with respect to the voltage drop only at the charging current detection resistor and strong against the component variation or the like can be detected.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
In FIG. 1, reference numeral 1 denotes an AC power source, and the AC input is supplied to a rectifying / smoothing circuit 3 via an input filter 2. After being rectified and smoothed by 3, it is supplied to the primary side of the transformer 4 and switched by the power MOSFET 5. The power MOSFET 5 is driven by being applied to its gate from a PWM (Pulse Wi-dth Modulation) control circuit 6 to perform a switching operation. Thereby, the secondary side output of the transformer 4 is controlled. The transformer 4 generates a predetermined output voltage on the secondary side by switching the primary side by the power MOSFET 5, and the secondary side output is supplied to the rectification / smoothing circuit 7, and is rectified and smoothed to direct current. After that, it is supplied to the secondary battery 9 via the switch unit 8. A high-accuracy charging current detection circuit 16 is inserted on the negative electrode side of the secondary battery 9, and the potential at this point is input to the output control circuit 11 as an output current signal. The voltage on the output side of the switch unit 8 is input to the output control circuit 11 and the battery voltage detection circuit 12 as an output voltage signal. The battery voltage detection circuit 12 detects the potential on the positive electrode side of the secondary battery 9, determines the end of charging, and controls the charging control circuit 13. The control of the state of charge by the charge control circuit 13 is displayed on the display unit 14. The output control circuit 11 is mainly composed of an error amplifier or the like, compares the rectified and smoothed secondary output voltage and output current with a reference value, and outputs the error output via the photocoupler circuit 15 to the PWM control circuit 6 Is output. As a result, rectified and smoothed secondary side output information is fed back to the primary side of the transformer 4 and PWM controlled, and when charging the secondary battery, the charger operates with constant current charging and high precision charging A system that operates with a constant voltage generated across the current detection circuit 16 can be obtained.

  When comparing the secondary output voltage and output current with the reference values, when the charger is operating at constant current charging, the high-accuracy current detection circuit 16 is controlled to low impedance and detects current with high efficiency. When the voltage generated at both ends of the detection resistor operates at a constant voltage detection circuit, the impedance of the high-precision current detection circuit 16 increases as the charging current of the secondary battery decreases. The voltage drop due to the charging current flowing through the high-accuracy current detection circuit 16 is larger than the voltage drop due to the charging current flowing through the charging current detection resistor 10, and is input to the output control voltage 11 when the charging current of the secondary battery is small. The output signal is a large output current signal.

  FIG. 2 shows a high-accuracy current detection circuit that is a characteristic part of the present embodiment. When the secondary output voltage and output current are compared with reference values, when the charger is operating at constant current charging, the current is detected with high efficiency by the charging current detection resistor 10 having a small resistance value. When the charger is operating at constant voltage charging, the voltage detection circuit 17 determines that the charger is operating at constant voltage charging, and the information is input to the resistance selection circuit 18. The resistance selection circuit 18 controls the switch unit 19 to be turned off, and the resistance value of the charging current detection resistor 10 connected in series with the charging current detection resistor 10 through the charging current detection resistor 10 is about 10 times the resistance value. The charging current also flows through the charging current detection resistor 20 having Compared to the voltage drop of only the charging voltage / current detection resistor 10, the voltage drop of the charging voltage / current detection resistor 10 and the charging voltage / current detection resistor 20 is large, so if the charging current of the secondary battery is small, the charger is charged at a constant voltage. Even during the operation, an output current signal that is larger than the output current signal of only the charging current detection resistor 10 is input to the output control voltage 11.

Comparing the detection characteristics using only the charging current detection resistor 10 and the detection characteristics using the high-accuracy current detection circuit in FIG. 2, the charging current when the charger is operating at constant voltage charging is I, and the charging current detection The resistance value of the resistor 10 is R, the error voltage due to variation is ΔV, and the resistance value of the charging current detection resistor 20 is 9R. The relative error when detecting the charging current using only the charging current detection resistor 10 is ΔV / (I ・ R)
It becomes. When the charging current is detected using the high-accuracy current detection circuit, the resistance value of the resistor through which the charging current flows is R + 9R = 10R. In that case, the relative error is ΔV / (I ・ 10R)
It becomes. In this case, the relative error becomes 1/10 as compared with the case where the charging current is detected using only the charging current detection resistor 10, and therefore the detection accuracy of the charging current is 10 times. By using the charging current detection circuit of FIG. 2, for example, in a region where the charger as shown in FIG. 4 is operating at constant voltage charging, even when the charging current gradually decreases, a highly accurate charging current can be detected. It becomes. Further, by using the charging current detection circuit shown in FIG. 2 in the charging apparatus as shown in FIG. 1, it is possible to detect the charging end current with high accuracy.

  In FIG. 2, the same effect can be obtained by connecting resistors in parallel as shown in FIG. In this case, when comparing the secondary output voltage and output current with the reference values, when the charger is operating at constant current charging, the current is detected with high efficiency by the charging current detection resistor 10 having a small resistance value. The When the charger is operating at constant voltage charging, the voltage detection circuit 17 determines that the charger is operating at constant voltage charging, and the information is input to the resistance selection circuit 18. The resistance selection circuit 18 controls the switch unit 19 to be turned off, and the resistance value of the charging current detection resistor 10 connected in parallel with the charging current detection resistor 10 through the charging current detection resistor 10 is about 10 times the resistance value. The charging current also flows through the charging current detection resistor 20 having Compared to the voltage drop of only the charging voltage / current detection resistor 10, the voltage drop of the charging voltage / current detection resistor 10 and the charging voltage / current detection resistor 20 is large, so if the charging current of the secondary battery is small, the charger is charged at a constant voltage. Even during the operation, an output current signal that is larger than the output current signal of only the charging current detection resistor 10 is input to the output control voltage 11.

(Embodiment 2)
Even in a charging device in which the AC power source 1 and the secondary battery 9 are not insulated as shown in FIG. 5, the high-accuracy charging end current can be detected by using the high-accuracy charging current detection circuit 16.

  The present invention is useful for charging a secondary battery such as a lithium ion battery.

Charging circuit block configuration diagram using the current detection circuit according to the first embodiment of the present invention The figure which shows the structural example 1 of the current detection circuit in Embodiment 1 of this invention. The figure which shows the structural example 2 of the current detection circuit in Embodiment 1 of this invention. Transient characteristic diagram of charge state in Embodiment 1 of the present invention Charging circuit block configuration diagram using the current detection circuit in Embodiment 2 of the present invention Charge circuit block configuration diagram using a conventional current detection circuit

Explanation of symbols

1 AC power supply 2 Input filter 3 Rectifier / smoothing circuit 4 Transformer 5 Power MOSFET
6 PWM control circuit 7 Rectification / smoothing circuit 8 Switch unit 9 Secondary battery 10 Charging current detection resistor 11 Output control circuit 12 Voltage detection circuit 13 Charge control circuit 14 Display unit 15 Photocoupler circuit 16 High-accuracy charging current detection circuit 17 Voltage detection Circuit 18 Resistance selection circuit 19 Switch unit 20 Charging current detection resistor

Claims (1)

  1. A secondary battery is mounted, and the output control means performs charging at a predetermined voltage or lower with a constant current, and controls charging to exceed the predetermined voltage with a constant voltage,
    While cutting off the charging current to the secondary battery at a predetermined cycle by the switching means,
    In the charging apparatus having the charging control means for controlling the charging by controlling the operation of the switching means by the charging control means,
    Provide a detection circuit to detect the current of the secondary battery,
    The charge control means includes
    Means for comparing with a reference value set to be smaller than the current detected as the output of the current detection means;
    A charging device comprising a detection circuit having a function of changing sensitivity according to a comparison result of the comparison means.
JP2004305506A 2004-10-20 2004-10-20 Charger Pending JP2006121797A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2004305506A JP2006121797A (en) 2004-10-20 2004-10-20 Charger

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2004305506A JP2006121797A (en) 2004-10-20 2004-10-20 Charger

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Publication Number Publication Date
JP2006121797A true JP2006121797A (en) 2006-05-11

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JP2004305506A Pending JP2006121797A (en) 2004-10-20 2004-10-20 Charger

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007020299A (en) * 2005-07-07 2007-01-25 Matsushita Electric Ind Co Ltd Charger
JP2008283743A (en) * 2007-05-08 2008-11-20 Fuji Electric Device Technology Co Ltd Secondary battery protective device and semiconductor integrated circuit device
US8035347B2 (en) 2007-07-25 2011-10-11 Sony Corporation Battery charger
JP2013051819A (en) * 2011-08-31 2013-03-14 Panasonic Corp Charger
TWI392194B (en) * 2007-07-25 2013-04-01 Sony Corp Battery charger
CN106487073A (en) * 2016-12-13 2017-03-08 合肥中感微电子有限公司 A kind of power supply circuits and electronic equipment
JP2018525961A (en) * 2016-02-05 2018-09-06 広東欧珀移動通信有限公司 Terminal charging system, charging method and power adapter
US10491030B2 (en) 2016-07-26 2019-11-26 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Charging system and charging method for terminal and terminal

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007020299A (en) * 2005-07-07 2007-01-25 Matsushita Electric Ind Co Ltd Charger
JP4526453B2 (en) * 2005-07-07 2010-08-18 パナソニック株式会社 Charger
JP2008283743A (en) * 2007-05-08 2008-11-20 Fuji Electric Device Technology Co Ltd Secondary battery protective device and semiconductor integrated circuit device
US8035347B2 (en) 2007-07-25 2011-10-11 Sony Corporation Battery charger
TWI392194B (en) * 2007-07-25 2013-04-01 Sony Corp Battery charger
TWI392193B (en) * 2007-07-25 2013-04-01 Sony Corp Battery charger and charging method
JP2013051819A (en) * 2011-08-31 2013-03-14 Panasonic Corp Charger
JP2018525961A (en) * 2016-02-05 2018-09-06 広東欧珀移動通信有限公司 Terminal charging system, charging method and power adapter
US10320225B2 (en) 2016-02-05 2019-06-11 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Charging system and charging method for increasing service life of battery of terminal and power adapter thereof
US10491030B2 (en) 2016-07-26 2019-11-26 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Charging system and charging method for terminal and terminal
CN106487073A (en) * 2016-12-13 2017-03-08 合肥中感微电子有限公司 A kind of power supply circuits and electronic equipment

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