Method and apparatus for suppressing time-varying signals in batteries undergoing charging or discharging

• US 5,343,380 A
• Filed: 11/17/1992
• Issued: 08/30/1994
• Est. Priority Date: 11/17/1992
• Status: Expired due to Fees

• Current Assignee: Keith S Champlin
• Original Assignee: Keith S Champlin
• Inventors: Champlin, Keith S.
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US07/977,560
• Time in Patent Office: 651 Days
• Field of Search: 322/58, 363/46, 320/14, 320/21
• US Class Current: 363/46
• CPC Class Codes: H02J 1/02 Arrangements for reducing harmonics or ripples

Abstract

An electronic device for effectively preventing time-varying current from passing through an electro-chemical cell or battery is disclosed. Time-varying current flowing in a circuit which includes the cell/battery is sensed externally to the cell/battery with a magnetically-coupled ac current probe thereby producing an induced time-varying signal. This induced signal is amplified to the level of the original time-varying current and applied to the cell/battery'"'"'s terminals in phase-opposition to the original current. As a result, the component of time-varying current flowing in the cell/battery'"'"'s external leads assumes an alternate path around the cell/battery and is effectively canceled within the cell/battery itself. Time-varying voltage across the cell/battery, which would normally result from time-varying current passing through its internal impedance, is likewise eliminated. Accordingly, measurements of the cell/battery'"'"'s incremental parameters can be performed with the cell/battery "on line" without measurement errors due to spurious charger- and load-related signals. Additional applications of the disclosed device include reducing or eliminating ripple and crosstalk in batteries that are supplying voltage-sensitive equipment, and preventing plate deterioration caused by ac currents flowing through a cell/battery.

Claims

1. An electronic device for reducing a time-varying current component passing through a dc power source, said dc power source a part of a circuit carrying said time-varying current component comprising:

means for sensing said time-varying current component flowing in said circuit and for producing a signal proportional thereto;

means for amplifying said signal and for producing an output signal proportional thereto between a pair of amplifier output terminals;

means for resistively coupling said amplifier output terminals to said dc power source and for passing a time-varying amplifier output current through said dc power source in phase opposition to said time-varying current component passing through said dc power source; and

,

means for sensing the voltage across said dc power source and for regulating the voltage between said pair of amplifier output terminals therewith to prevent excessive dc current from flowing through said means for resistively coupling said amplifier output terminals to said dc power source.

2. An electronic device according to claim 1 wherein said means for sensing said time-varying current component comprises a magnetically coupled current probe coupled to said circuit.

3. An electronic device for reducing a time-varying voltage between a pair of nodes located in a conducting path carrying a time-varying current comprising:

means for sensing said time-varying current flowing in said conducting path and for producing a signal proportional thereto;

means for amplifying said signal and for producing an output signal proportional thereto between a pair of amplifier output terminals;

means for resistively coupling said amplifier output terminals to said pair of nodes and for conducting a time-varying amplifier output current into one of said pair of nodes and out of the other of said pair of nodes in phase opposition to said time-varying current passing between said pair of nodes in said conducting path; and

,

means for sensing the voltage between said pair of nodes and for regulating the voltage between said pair of amplifier output terminals therewith to prevent excessive dc current from flowing through said means for resistively coupling said amplifier output terminals to said pair of nodes.

4. An electronic device according to claim 3 wherein said means for sensing said time-varying current comprises a magnetically coupled current probe coupled to said conducting path.

5. An electronic device for passing a time-varying current through first and second terminals having a dc potential difference between them while preventing the flow of direct current through said electronic device comprising:

operational amplifier means having an inverting input terminal, a non-inverting input terminal, an output terminal, and a pair of power terminals;

power amplifier means having an input terminal, an output terminal, and a pair of power terminals, said input terminal of said power amplifier means coupled to said output terminal of said operational amplifier means;

power supply means having power supply terminals coupled to said pair of power terminals of said operational amplifier means and to said pair of power terminals of said power amplifier means, one of said power supply terminals also coupled to said second terminal;

first resistive means coupling said output terminal of said power amplifier means to said first terminal;

second resistive means coupling said output terminal of said power amplifier means to said inverting input terminal of said operational amplifier means;

third resistive means coupling said non-inverting input terminal of said operational amplifier means to said first terminal; and

,

time-varying signal source means coupled to said inverting input terminal and to said non-inverting input terminal of said operational amplifier means.

6. An electronic device according to claim 5 wherein said time-varying signal source means comprises a magnetically coupled current probe sensing a time-varying current flowing into one of said first and second terminals.

7. An electronic device for reducing the dynamic Thevenin'"'"'s impedance of a dc voltage source having a pair of voltage source output terminals comprising:

means for sensing changes in current flowing within said dc voltage source between said voltage source output terminals and for producing a signal proportional to a time-varying component of said current;

means for amplifying said signal and for producing an output signal proportional thereto between a pair of amplifier output terminals;

means for resistively coupling said amplifier output terminals to said voltage source output terminals and for passing a time-varying amplifier output current through said dc voltage source in opposition to said changes in current flowing through said dc voltage source; and

,

means for sensing the voltage across said pair of voltage source output terminals and for regulating the voltage between said pair of amplifier output terminal therewith to prevent excessive dc current from flowing through said means for resistively coupling said amplifier output terminals to said voltage source output terminals.

8. An electronic device according to claim 7 wherein said means for sensing changes in current flowing through said dc voltage source comprises a magnetically coupled current probe.