Method of charging a secondary battery and apparatus for the same
First Claim
1. An apparatus for charging a secondary battery having a function of shutting off, upon detecting an overcharge voltage, a charging path to the batter to thereby obviate overcharging, comprising:
- a DC power feeding circuit for feeding a preselected DC voltage and a preselected DC current for charging the secondary battery;
a switching circuit for pulsing an output of said DC power feeding circuit to thereby pulse switch a charge current for the secondary battery;
a first control circuit for controlling a DC voltage fed from said DC power feeding circuit to a preselected voltage lower than the overcharge voltage of the secondary battery;
a current limiting circuit for limiting a DC voltage fed from said DC power feeding circuit to a preselected current, said current limiting circuit being capable of selectively switching the DC current to at least a first current for a constant current range or a second current lower than said first current and corresponding to a current to appear at an end of a charging operation; and
a second control circuit for controlling said switching circuit, said first control circuit and said current limiting circuit on a basis of a terminal voltage of the secondary battery, an output voltage of said DC power feeding circuit and a charge current to thereby control charging of the secondary battery;
said second control circuit causing said current limiting circuit to maintain said first current until the terminal voltage of the secondary battery reaches a full charge voltage, while causing said switching circuit to pulse said first current, and causing, upon detecting a rise of the terminal voltage to the full charge voltage, said current limiting circuit to switch said first current and said second current in a form of pulses to thereby charge the secondary battery with resulting bilevel pulse currents.
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Accused Products
Abstract
A charging apparatus for charging a secondary battery of the present invention includes a DC/DC converter for outputting a preselected DC voltage and a preselected DC current limited by a voltage setting circuit and a current limiting circuit, respectively. A control circuit senses the voltage of a secondary battery connected to the apparatus and causes the current limiting circuit to set up a first current lying in a constant current range until the battery voltage reaches a full charge voltage. At this instant, the control circuit switches a charge switching circuit in order to apply the first current to the battery in the form of pulses. As soon as the battery voltage reaches the full charge voltage, the control circuit applies a current lower than the current in the constant current range and the current in the constant range to the battery alternately in the form of bilevel pulses. The apparatus is capable of reducing charging time without increasing loads on switching devices, and insures the safety of the battery.
77 Citations
24 Claims
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1. An apparatus for charging a secondary battery having a function of shutting off, upon detecting an overcharge voltage, a charging path to the batter to thereby obviate overcharging, comprising:
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a DC power feeding circuit for feeding a preselected DC voltage and a preselected DC current for charging the secondary battery; a switching circuit for pulsing an output of said DC power feeding circuit to thereby pulse switch a charge current for the secondary battery; a first control circuit for controlling a DC voltage fed from said DC power feeding circuit to a preselected voltage lower than the overcharge voltage of the secondary battery; a current limiting circuit for limiting a DC voltage fed from said DC power feeding circuit to a preselected current, said current limiting circuit being capable of selectively switching the DC current to at least a first current for a constant current range or a second current lower than said first current and corresponding to a current to appear at an end of a charging operation; and a second control circuit for controlling said switching circuit, said first control circuit and said current limiting circuit on a basis of a terminal voltage of the secondary battery, an output voltage of said DC power feeding circuit and a charge current to thereby control charging of the secondary battery; said second control circuit causing said current limiting circuit to maintain said first current until the terminal voltage of the secondary battery reaches a full charge voltage, while causing said switching circuit to pulse said first current, and causing, upon detecting a rise of the terminal voltage to the full charge voltage, said current limiting circuit to switch said first current and said second current in a form of pulses to thereby charge the secondary battery with resulting bilevel pulse currents. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of charging a secondary battery having a function of shutting off, upon detecting an overcharge voltage, a charging path to the battery to thereby obviate overcharging, comprising the steps of:
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repeatedly pulsing a preselected first current, which starts decreasing when a terminal voltage of the secondary battery reaches a full charge voltage, until the terminal voltage reaches the full charge voltage, thereby charging the secondary battery; replacing, upon detecting a rise of the terminal voltage to the full charge voltage, said preselected first current with a second current lower than said first preselected current and corresponding to a current to appear when fully charged, while again replacing said second current with said preselected first current when the terminal voltage falls below the full charge voltage, and pulsing said first preselected current and second current alternately, thereby further charging the secondary battery with bilevel pulse currents; and stopping charging the secondary battery when said preselected first current sequentially decreases to reach a value corresponding to said second current, determining that a charging operation has completed. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method of charging a secondary battery having a function of shutting off, upon detecting an overcharge voltage, a charging path to the battery to thereby obviate overcharging, comprising the steps of:
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repeatedly pulsing a preselected first current, which starts decreasing when a terminal voltage of the secondary battery reaches a full charge voltage, until the terminal voltage reaches a first voltage corresponding to the full charge voltage, thereby charging the secondary battery by pulse charging; replacing, upon detecting a rise of the terminal voltage to said first voltage, said preselected first current with a second current lower than said preselected first current and corresponding to a current to appear when fully charged, while again replacing said second current with said preselected first current when the terminal voltage falls below the full charge voltage, and alternately switching said preselected first current and second current in a form of pulses, thereby further charging the secondary battery with bilevel pulse currents; replacing, when the terminal voltage reaches a second voltage that is higher than said first voltage, but lower than the full charge voltage, said first preselected current with said second current, thereby further charging the secondary battery by pulse charging; switching said first preselected current and said second current in a form of pulses, thereby further charging the secondary battery with bilevel pulse currents; and stopping charging when said preselected first current sequentially decreases to reach a value corresponding to said second current during pulse charging, determining that a charging operation has been completed. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification