BATTERY CHARGING CURRENT AND TERMINATION CONTROL CIRCUITRY

• US 3,660,748 A
• Filed: 03/02/1970
• Issued: 05/02/1972
• Est. Priority Date: 03/03/1969
• Status: Expired due to Term

• Current Assignee: Dennis Albert Clayton
• Original Assignee: Dennis Albert Clayton
• Inventors: Clayton, Dennis Albert
• Primary Examiner(s): Shoop, Jr., William M.
• Application Number:
  US05/015,627
• Time in Patent Office: 792 Days
• Field of Search: 320/23,24,27,28,32,33,39,40,43
• US Class Current: 320/125
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/12 using magnetic devices having controllable degree of saturation, i.e. transductors

Abstract

To reduce the charging current in the latter part of a charge, an automatic battery-charging apparatus includes means for comparing a sample voltage depending on the battery voltage while on charge, with a reference voltage which is progressively increased throughout the charge, and using a function of the difference to control the charging current. Thus if the battery voltage and sample voltage increase more rapidly than the reference voltage, the charging current is reduced and vice versa. The reference voltage may be supplied by a motor-driven potentiometer, or by a progressivley charged capacitor. The duration of the charge is also controlled so that a phase of the charge is terminated when the value or rate of change of the sample voltage, having exceeded that of the reference voltage, then falls below it.

Claims

1. Automatic electric battery charging apparatus comprising means for establishing a reference voltage and progressively increasing it during a charging cycle, means for comparing the reference voltage with a sample voltage which is a function of the battery voltage while on charge to derive an error signal corresponding to a function of the difference between the rate of change of the sample voltage and that of the reference voltage, means for decreasing the battery charging current when the error signal is positive and increasing the battery charging current when the error signal is negative, and means for interrupting the battery charging circuit to terminate the charge for at least a part of said charging cycle when said error signal is negative after having previously been positive.

2. Apparatus as claimed in claim 1 in which the error signal corresponds to the difference between the rates of change of the sample voltage and the reference voltage.

3. Apparatus as claimed in claim 1 in which the error signal corresponds to the difference between the values of the sample voltage and the reference voltage.

4. Apparatus as claimed in claim 1 in which the charge is terminated when the sample voltage falls below the reference voltage.

5. Apparatus as claimed in claim 2 in which the sample voltage at all times exceeds the reference voltage, and the charge is terminated when the error signal begins to decrease having previously increased.

6. Automatic electric battery charging apparatus comprising a reference capacitor to provide a progressively increasing reference voltage during a charging cycle by being charged from a sample voltage which is a function of the battery voltage while on charge, the capacitor charging current being dependent upon the difference between the sample voltage and the reference voltage, means for decreasing the battery charging current when the capacitor charging current increases and increasing the battery charging current when the capacitor charging current decreases, and means for interrupting the battery charging circuit to terminate the charge for at least part of said charging cycle when the reference capacitor charging current falls, after having previously risen, as the battery approaches the fully charged condition.

7. Apparatus as claimed in claim 6 in which delay means are provided to prevent said termination of the charge when the reference capacitor charging current rises and then falls at the beginning of the charging cycle.

8. Automatic electric battery charging apparatus comprising charging means for generating an output to charge a battery, means for automatically adjusting said output during charging to increase the battery voltage to a datum value, and means for progressively increasing the datum value during at least a part of a charging cycle.

9. Apparatus as claimed in claim 8 further comprising means for establishing a reference voltage proportional to said datum value, means for progressively increasing said datum value during a charging cycle, means for comparing said reference voltage with a sample voltage proportional to the battery vOltage during charging to derive an error signal which corresponds to a function of the difference between said sample voltage and said reference voltage, and means for varying said charging output in response to said error signal tending to cause the battery voltage to conform to the increases of said datum value.

10. Apparatus as claimed in claim 9 wherein said error signal also provides a signal for the termination of at least part of the charge cycle.

11. Apparatus as claimed in claim 9 wherein said means for varying the charging current is controlled by a comparator circuit responsive to a difference between the sample voltage and the reference voltage.

12. Apparatus as claimed in claim 9 wherein the reference voltage is established and progressively increased by a capacitor which is charged from the sample voltage.

13. Apparatus as claimed in claim 8 wherein the battery charging current is adjusted by a motor-driven tap-changing transformer supplying the charging current through a rectifier.

14. Apparatus as claimed in claim 8 wherein the battery charging current is adjusted by a saturable reactor controlling the A.C. input to a rectifier supplying the battery charging current.

15. Apparatus as claimed in claim 8 wherein the battery charging current is adjusted by varying the average output of a pulsing circuit.

16. Apparatus as claimed in claim 8 wherein the termination of the charge for at least part of said charging cycle is dependent upon the simultaneous operation of an operating relay and a memory relay, said latter relay is energized when said former relay is not energized and is provided with a holding circuit so as to remain energized when the operating relay is subsequently energized again.

17. Apparatus as claimed in claim 8 wherein the sample voltage is the same as the battery voltage for the charging of batteries of equal nominal voltages.

18. Apparatus as claimed in claim 8 wherein manual means is provided for adjusting the relationship between the sample voltage and the battery voltage for the charging of batteries each having different voltages.

19. Apparatus as claimed in claim 8 wherein means are provided for automatically adjusting the sample voltage to a given initial value for the charging of batteries each having different voltages.

20. Apparatus as claimed in claim 9 wherein the battery voltage and said sample voltage follow increases of said reference voltage up to a maximum charging output throughout the charging cycle.

21. Apparatus as claimed in claim 20 wherein said means for increasing said reference voltage operates at a predetermined maximum rate of increase.

22. Apparatus as claimed in claim 21 wherein the reference voltage is established and progressively increased by a motor-driven potentiometer.

23. Apparatus as claimed in claim 21 wherein said means for increasing the reference voltage is arrested by said error signal until said error signal has been reduced below a predetermined value.

24. Apparatus as claimed in claim 9 wherein said error signal corresponds to the difference between the values of said sample voltage and said reference voltage.

25. Apparatus as claimed in claim 9 wherein said error signal corresponds to the difference between the rates of change of said sample voltage and said reference voltage.

26. A method of automatically charging a battery comprising the steps of:

charging said battery from apparatus providing a charging current, automatically adjusting the charging current to bring the battery voltage to a datum voltage value during charging, and progressively increasing said datum value during a charging cycle.

27. A method as claimed in claim 26 further comprising the step of adjusting said charging current to cause the battery voltage to follow increases of said datum value up to a maximum charging current throughout the charging cycle.

28. A method as claimed in claim 26 further comprising the step of selecting the initial datum value at the Beginning of a charge cycle to exceed the initial battery voltage during charge at the maximum charging current of said apparatus.

29. A method as claimed in claim 27 further comprising the step of arresting the increasing of said datum value for a period terminated when said step of adjusting said charging current does not cause the battery voltage to be substantially equal to said datum value.