Method for the fast charging of a battery and integrated circuit for the implementation of this method
First Claim
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1. A method for fast charging of a battery comprising the steps of:
- applying a charging current to the battery;
measuring a battery voltage during the step of applying and obtaining a first measurement signal therefrom;
generating a second signal, representing a variation of the battery voltage during a period;
determining when the battery voltage is at a rated value by identifying an instant at which the battery voltage measured during a period increases at a lower rate of change than during a preceding period; and
stopping the charging of the battery responsive to the battery voltage reaching the rated value;
wherein the step of determining that the battery voltage measured during a period increases at a lower speed than during a previous period, further includes the steps of;
dampening the second signal for a first time to generate a third measurement signal;
dampening the third measurement signal, to generate a fourth measurement signal; and
verifying that a ratio of the third measurement signal to the fourth measurement signal is greater than a threshold value before performing the step of determining; and
detecting a point of time when the third measurement signal passes through an extreme value.
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Abstract
To carry out a fast charging of a battery, a high current is injected into this battery while, at the same time, the terminals of this battery are monitored. This injection is stopped when this voltage undergoes an inflection of its variation. It is shown that, given the security of the system, it is possible to charge nickel-cadmium or nickel-metal-hydride type batteries with currents that are even higher than in prior systems.
15 Citations
36 Claims
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1. A method for fast charging of a battery comprising the steps of:
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applying a charging current to the battery; measuring a battery voltage during the step of applying and obtaining a first measurement signal therefrom; generating a second signal, representing a variation of the battery voltage during a period; determining when the battery voltage is at a rated value by identifying an instant at which the battery voltage measured during a period increases at a lower rate of change than during a preceding period; and stopping the charging of the battery responsive to the battery voltage reaching the rated value; wherein the step of determining that the battery voltage measured during a period increases at a lower speed than during a previous period, further includes the steps of; dampening the second signal for a first time to generate a third measurement signal; dampening the third measurement signal, to generate a fourth measurement signal; and verifying that a ratio of the third measurement signal to the fourth measurement signal is greater than a threshold value before performing the step of determining; and detecting a point of time when the third measurement signal passes through an extreme value. - View Dependent Claims (2, 3, 4, 5)
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6. A method for charging a battery, comprising the steps of:
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applying a charging current to the battery; measuring, at a predetermined period, a voltage across the battery that changes in response to the applied charging current to generate a succession of measurement values; computing a succession of difference values each indicative of a difference between a pair of measurement values; dampening the difference values a first time to generate a first-dampened succession of difference values; searching, responsive to at least one condition, for an extreme value of the first-dampened succession of difference values; identifying the extreme value; and stopping the charging of the battery responsive to an identification of the extreme value by the step of identifying. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An apparatus for charging a battery, comprising:
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means for applying a charging current to the battery; first means for generating a succession of measurements of battery voltage, the battery voltage varying in response to the applied charging current; second means for generating a succession of difference values each indicative of a difference between a pair of battery voltage measurements; third means for generating a succession of first-dampened difference value each indicative of a previous first-dampened difference value and a present difference value; means for detecting an extreme point in the succession of first-dampened difference values, at which the first-dampened difference values change from an increasing trend to a decreasing trend; and means, operative in response to a detection by the means for detecting, for stopping the charging current. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An integrated circuit for controlling the charging of a battery, comprising:
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measurement means for generating a sequence of battery voltage measurements; memory means for storing the battery voltage measurements; nonvolatile memory means for storing a list of program instructions; and processor means for reading the list of programming instructions from the nonvolatile memory and for controlling the measurement means; wherein the processor means further includes; means for computing a succession of difference values each indicative of a difference between a pair of battery voltage measurements; means for smoothing the difference values to generate a sequence of first-dampened difference values; means for identifying an extreme value in the first-dampened difference values; and means, operative in response to identifying the maximum value, for issuing a command to stop the charging of the battery.
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34. An apparatus for charging a battery, comprising:
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an adjustable voltage regulator having an input terminal coupled to a power supply, a output terminal, and an adjust terminal, the adjust terminal being coupled to a first terminal of the battery; an impedance, coupled between the output terminal and the adjust terminal, for selecting a constant current that couples from the adjustable voltage regulator to the battery; a switch, responsive to a control signal, for alternately conducting and blocking the constant current; and an integrated circuit coupled to the battery, for monitoring the voltage across the battery, and for issuing the control signal to block the constant current when the battery becomes fully charged. - View Dependent Claims (35, 36)
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Specification