DIFFERENTIAL CURRENT MONITORING FOR PARALLEL-CONNECTED BATTERIES

• US 20120182021A1
• Filed: 01/17/2012
• Published: 07/19/2012
• Est. Priority Date: 01/18/2011
• Status: Active Grant

• Current Assignee: Tiax, LLC
• Original Assignee: Tiax, LLC
• Inventors: Ofer, David, McCoy, Christopher H.
• Granted Patent: US 9,678,163 B2
• Time in Patent Office: Days
• US Class Current: 324/433
• CPC Class Codes: G01R 19/10 Measuring sum, difference or ratio
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/3832 without measurement of battery voltage
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system for determining battery characteristics based on differential current monitoring includes a first battery; a second battery, the second battery being connected in parallel with the first battery; and a differential current measurement module comprising at least one current measuring device, the differential current measurement module being configured to determine a differential current associated with the first battery and the second battery. A method for determining battery characteristics based on differential current monitoring includes determining a differential current associated with a first battery and a second battery, the first battery being connected in parallel with the second battery.

Claims

1. A system for determining battery characteristics based on differential current monitoring, the system comprising:

a first battery;

a second battery, the second battery being connected in parallel with the first battery; and

a differential current measurement module comprising at least one current measuring device, the differential current measurement module being configured to determine a differential current associated with the first battery and the second battery.

2. The system of claim 1, wherein the differential current measurement module is further configured to detect a fault in the first battery based on the determined differential current.

3. The system of claim 1, wherein the differential current measurement module comprises a first current measuring device configured to measure a first current associated with the first battery, and a second current measuring device configured to measure a second current associated with the second battery, wherein the differential current comprises a difference between the first current and the second current.

4. The system of claim 3, wherein the first and second current measuring devices each comprise one of a Hall Effect transducer, a current sense resistor, an induction sensor, a current shunt, and current sense resistor with amplification.

5. The system of claim 1, wherein the differential current measurement module comprises a first current measuring device configured to measure a first current associated with one of the first battery and the second battery, and a second current measuring device configured to measure a total current in the first battery and the second battery, wherein the differential current is determined based on the first current and the total current.

6. The system of claim 5, wherein the first and second current measuring devices each comprise one of a Hall Effect transducer, a current sense resistor, an induction sensor, a current shunt, and current sense resistor with amplification.

7. The system of claim 1, further comprising

a third battery;

a fourth battery, the second battery being connected in parallel with the third battery; and

an additional differential current measurement module configured to determine a differential current associated with the third battery and the fourth battery, wherein the system is configured to compare the differential current associated with the first battery and the second battery with the differential current associated with the third battery and the fourth battery.

8. A system for determining battery characteristics based on differential current monitoring, the system comprising:

a first battery;

a second battery, the second battery being connected in parallel with the first battery; and

a differential current measurement module configured to determine a differential current associated with the first battery and the second battery, wherein the differential current measurement module comprises a switch and a current measuring device located between the first battery and the second battery.

9. The system of claim 8, wherein the switch is configured to:

disconnect the first battery from the second battery; and

reconnect the first battery and the second battery after elapsing of a diagnostic time period;

wherein the current measuring device is configured to determine the differential current associated with the first battery and the second battery after the first battery and the second battery are reconnected.

10. The system of claim 8, wherein the differential current measurement module is further configured to compare the determined differential current to a minimum fault threshold to determine the presence of a fault in the first battery.

11. The system of claim 8, wherein the switch and the current measuring device comprise a metal-oxide-semiconductor field effect transistor (MOSFET), and wherein the differential current is determined based on a drain-source voltage of the MOSFET.

12. The system of claim 8, wherein the current measuring device comprises one of a Hall Effect transducer, a current sense resistor, an induction sensor, a current shunt, and current sense resistor with amplification.

13. The system of claim 8, wherein the switch comprises one of a relay, a solid state switch, a thyristor, and a mechanical switch.

14. The system of claim 8, wherein the first battery comprises a first cell and a second cell connected in parallel, and further comprises an additional differential current measurement module comprising an additional switch located between the first cell and the second cell, the additional switch being configured to:

disconnect the first cell from the second cell after the presence of a fault in the first battery is determined; and

reconnect the first cell and the second cell after elapsing of a diagnostic time period;

wherein the additional differential current measurement module further comprises an additional current measuring device configured to determine a differential current associated with the first cell and the second cell after the first cell and the second cell are reconnected.

15. A method for determining battery characteristics based on differential current monitoring, the method comprising:

determining a differential current associated with a first battery and a second battery, the first battery being connected in parallel with the second battery.

16. The method of claim 15, further comprising detecting a fault in the first battery based on the determined differential current.

17. The method of claim 15, further comprising determining an average value of the differential current over a predetermined time period, and detecting the fault in the first battery based on the determined average value.

18. The method of claim 17, wherein detecting the fault in the first battery based on the determined average value comprises detecting a shift in a magnitude in the average value of the differential current during the predetermined time period.

19. The method of claim 15, wherein determining the differential current associated with a first battery and a second battery comprises:

determining a first current associated with the first battery;

determining a second current associated with the second battery; and

determining a difference between the first current and the second current.

20. The method of claim 15, further comprising

determining a differential current associated with a third battery and a fourth battery, the third battery being connected in parallel with the fourth battery;

and

comparing the differential current associated with the first battery and the second battery with the differential current associated with the third battery and the fourth battery.

21. The method of claim 15, further comprising:

disconnecting the first battery from the second battery by a switch that is located between the first battery and the second battery;

reconnecting the first battery and the second battery by the switch after elapsing of a diagnostic time period, wherein determining the differential current associated with the first battery and the second battery is performed after the first battery and the second battery are reconnected; and

comparing the determined differential current to a minimum fault threshold to determine the presence of a fault in the first battery.

22. The method of claim 21, further comprising connecting the first battery and the second battery for a predetermined time period before disconnecting the first battery and the second battery such that the first battery and the second battery are at a steady state before disconnecting the first battery and the second battery by the switch;

and

disconnecting the first battery from the second battery by the switch responsive to detection of the fault in the first battery.

23. The method of claim 21, wherein the first battery comprises a first cell and a second cell connected in parallel, and further comprises an additional differential current measurement module comprising an additional switch located between the first cell and the second cell, the method further comprising:

disconnecting the first cell from the second cell after the presence of the fault in the first battery is determined by the additional switch;

reconnecting the first cell and the second cell after elapsing of a diagnostic time period;

determining a differential current associated with the first cell and the second cell after the first cell and the second cell are reconnected; and

comparing the determined differential current to a minimum fault threshold to determine the presence of a fault in the first cell.