Charging apparatus with battery voltage monitoring circuitry

• US 5,212,439 A
• Filed: 04/02/1991
• Issued: 05/18/1993
• Est. Priority Date: 04/05/1990
• Status: Expired due to Fees

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Morioka, Toru, Sano, Masato
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US07/679,485
• Time in Patent Office: 777 Days
• Field of Search: 320/20, 320/21, 320/22, 320/23, 320/24, 320/37, 320/38, 320/39, 320/40, 320/31, 320/32
• US Class Current: 320/161
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

The charging apparatus for charging a secondary battery by controlling the charging current on the basis of the change with time of the voltage of the secondary battery through sampling of the voltage. The voltage of the secondary battery is sampled by use of a voltage/frequency converter which converts the voltage of the secondary battery to pulses of a frequency corresponding to the voltage and a counter which counts the converted pulses for a predetermined time with a predetermined cycle. The counting time of the counter is set to be larger than half a cycle of a commercial alternating current source used as a charging power source. Short duration fluctuations in the battery voltage due to charging power source variations are compensated for because the average voltage during this time is converted to digital values, thus making it possible to sample the voltage of the secondary battery correctly without being influenced by the change of the voltage of the power source.

Claims

1. A voltage sampling apparatus for sampling the voltage of a battery, comprising:

voltage/frequency converting means for converting the voltage of said battery to pulses of a frequency corresponding to the voltage;

a counter for counting said pulses and providing a series of counts on a predetermined cycle; and

comparator means for evaluating successive counts in said series to detect a change in said voltage.

2. A voltage sampling apparatus as set forth in claim 1, wherein said counter counts for a period longer than half a cycle of an alternating current source for use in charging said battery.

3. A charging apparatus which samples the voltage of a battery to control a charging current of said battery on the basis of the change in the voltage of said battery, comprising:

sampling means, for sampling the voltage of said battery, including a voltage/frequency converter which converts the voltage of said battery to pulses of a frequency corresponding to the voltage, and a counter which counts said pulses and provides a series of counting numbers representative of the frequency of said pulses on a predetermined cycle; and

control means for controlling the charging current of said battery on the basis of the counting number of said counter, including comparator means for evaluating successive counting numbers in said cycle.

4. A charging apparatus as set forth in claim 3, wherein said counter counts for a period longer than half a cycle of an alternating current source for use in charging said battery.

5. A charging apparatus which samples the voltage of a battery to control a charging current of said battery on the basis of the change in the voltage of said battery, comprising:

sampling means, for sampling the voltage of said battery, including a voltage/frequency converter which converts the voltage of said battery to pulses of a frequency corresponding to the voltage,

a counter which counts said pulses and provides a series of counting numbers representative of the frequency of said pulses on a predetermined cycle; and

control means for controlling the charging current of said battery on the basis of the counting number of said counter, including comparator means for evaluating successive counting numbers in said cycle, and detecting means for detecting the counting number of said counter to output a signal when a counting number in said series is less than the preceding counting number, and stopping means for stopping the charging current of said battery upon receipt of said signal from said detecting means.

6. A charging apparatus which samples the voltage of a battery to control a charging current of said battery on the basis of the change in the voltage of said battery, comprising:

sampling means, for sampling the voltage of said battery, including a voltage/frequency converter which converts the voltage of said battery to pulses of a frequency corresponding to the voltage,

a counter which counts said pulses and provides a series of counting numbers representative of the frequency of said pulses on a predetermined cycle;

control means for controlling the charging current of said battery on the basis of the counting number of said counter, including comparator means for evaluating successive counting numbers in said cycle;

first signal generating means for generating an inhibiting signal for a first predetermined time period after the start of the charging current of said battery to inhibit the counting by said counter; and

second signal generating means for generating a control signal a second predetermined time later from the start of the charging current of said battery irrespective of the counting number of said counter for causing said control means to control the charging current of said battery.

7. A charging apparatus for charging a battery, comprising:

voltage/frequency converting means for converting the voltage of said battery to pulses of a frequency corresponding to the voltage;

a first counter for counting said pulses and for providing a series of counting numbers representative of the frequency of said pulses on a predetermined cycle;

a register for storing the maximum counting number of said first counter;

a comparator which compares the counting number of said first counter with the content stored in said register and outputs a first signal when the counting number of said first counter is smaller than the content of said register;

a second counter for counting the number of first signals output from said comparator and for generating a second signal when said number of first signals reaches a predetermined number; and

control means for controlling the charging of said battery on the basis of said second signal from said second counter.

8. A charging apparatus as set forth in claim 7, wherein said predetermined number is at least two.

9. A charging apparatus for charging a battery, comprising:

voltage/frequency converting means for converting the voltage of said battery to pulses of a frequency corresponding to the voltage;

a first counter for counting said pulses and for providing a series of counting numbers representative of the frequency of said pulses on a predetermined cycle;

a register for storing the maximum counting number of said first counter;

a comparator which compares the counting number of said first counter with the content stored in said register for generating a first signal when the counting number of said first counter is larger than the content of said register and for generating a second signal when the counting number of said first counter is smaller than the content of said register;

a second counter for counting the number of first signals from said comparator and for updating the content of said register to the counting number of said first counter, when the number of first signals reaches a first predetermined number;

a third counter for counting the number of second signals from said comparator and for generating a third signal when the number of second signals reaches a second predetermined number; and

control means for controlling the charging of said secondary battery on the basis of said third signal from said third counter.

10. A charging apparatus as set forth in claim 9, wherein said second predetermined number is at least two.