Process and circuit versions for charging accumulators

• US 5,256,957 A
• Filed: 09/10/1990
• Issued: 10/26/1993
• Est. Priority Date: 03/11/1988
• Status: Expired due to Term

• Current Assignee: Gerhard Wiesspeiner
• Original Assignee: Gerhard Wiesspeiner
• Inventors: Wiesspeiner, Gerhard
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US07/474,837
• Time in Patent Office: 1,142 Days
• Field of Search: 320/20, 320/37, 320/39, 320/48, 320/32
• US Class Current: 320/122
• CPC Class Codes: H02J 7/00718 in response to charge current gradient
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

Process for charging accumulators and circuit versions for implementing said process. The charging state of a 100% charged accumulator is determined by the detection of an extreme value in the trend of a parameter (S), which is related to the inner voltage or the inner resistance of the accu. The extreme value can be detected by means of electronic analog-digital or computer circuits. These circuits can be produced by discrete or hybrid technology and can be integrated on a monolithic substrate. Besides an improvement in reliability, the process is applicable for charging undetermined accumulators directly out of unstable sources like solar generators, dynamos, weak supplies, or similar.

Claims

1. A process for quickly charging at least one accumulator to a terminal voltage with a variable charging current comprising the steps of:

characterizing the accumulator by an equivalent circuit including an inner variable resistance having a value which is a function of the charging state of the accumulator during the charging process;

applying the charging current at a selected terminal voltage to the accumulator;

at least one of measuring both the charging current and the terminal voltage and adjusting at least one of the both to a known value and measuring the other;

calculating from a temporal time course of the charging current and the terminal voltage a parameter (S) representative of at least one of the inner resistance and the inner accumulator voltage, and calculating dS/dt, the gradient of (S) with respect to time;

reducing the applied charge when the gradient is substantially equal to zero at a maximum value of the inner resistance indicative of a full charge state of the accumulator.

2. The process of claim 1, wherein applying the charging current comprises varying at least one of the terminal voltage and the current.

3. The process of claim 1, including the step of filtering variations in the applied charging current to derive a time varying signal corresponding to the parameter (S).

4. The process of claim 1, further comprising deriving a gradient of the accumulator voltage and setting the gradient to a reference by adjusting the current.

6. The process of claim 1, further comprising rapidly discharging the accumulator for regenerating its charge capacity.

7. The process of claim 1, wherein the at least one accumulator includes a plurality of such accumulators connected in series and the method further includes the step of selectively b-by-passing individual accumulators upon reaching a predetermined charge level indicative of a full charge condition for preventing said selected accumulators from becoming overcharged.

8. The process of claim 1 further including the steps of transforming and rectifying a line voltage for providing a pulsating DC charging current and measuring the accumulator voltage in sync with minimum values of the pulsating current for deriving (S) from said measured accumulator voltage.

5. The process of claim 23, further including adjusting the accumulator voltage until a selected minimum of said charging current is achieved.

9. Apparatus for quickly charging at least one accumulator to a terminal voltage with a variable charging current wherein said accumulator is characterized by an equivalent circuit including an inner resistance having a value which is a function of the charging state of the accumulator during the charging process comprising:

means for establishing charging current and terminal voltage for the accumulator;

source means for applying the charging current to the accumulator at a selected terminal voltage;

means responsive to time variations in the charging current and terminal voltage for calculating a parameter (S) representative of at least one of the inner resistance and the inner accumulator voltage;

means for calculating the dS/dt, the gradient of (S) with respect to time;

means responsive to the gradient and the parameter (S) for reducing the applied charge when the gradient is substantially equal to zero at a maximum value of the inner resistance indicative of a full charge state of the accumulator;

source means for applying the charging current to the accumulator.

10. The apparatus of claim 9, wherein the source means is operative to produce a varying input to the accumulator and further including filtering means responsive to the current and the voltage for producing time varying signals representative thereof.

11. The apparatus of claim 9, further including switch-off logic means coupled to the source and responsive for selectively switching the source into and out of circuit with the accumulator.

12. The apparatus of claim 9, further including means coupled to the logic means for periodically rapidly discharging the accumulator for regenerating its charge capacity.

13. The apparatus of claim 9 wherein a plurality of such accumulators are connected in series and further including means for selectively by-passing individual ones of the accumulators upon reaching a predetermined charge level indicative of a full charge condition for preventing said selected accumulators from becoming overcharged.

14. The apparatus of claim 9, including means for adjusting at least one of the terminal voltage and the charging current.

15. The apparatus of claim 9, further including means for measuring at least one of the terminal voltage in the charging current.

16. The apparatus of claim 9, further including means for sensing the inner voltage corresponding to the inner resistance for the equivalent circuit for automatically adjusting the charging current and accumulator voltage to the specific connected accumulator.