VEHICLE BATTERY PACK CELL VOLTAGE DETERMINATION

• US 20140100711A1
• Filed: 10/10/2012
• Published: 04/10/2014
• Est. Priority Date: 10/10/2012
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: GIBBS, JAMES C.
• Granted Patent: US 9,091,738 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• 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: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Methods and systems are provided that determine a voltage of a cell of a battery pack of a vehicle. A sensor is configured to measure a preliminary value of the voltage of the cell while the battery pack is being balanced. A processor is coupled to the sensor, and is configured to determine an offset from balancing of the battery pack, and calculate an adjusted value of the voltage of the cell using the preliminary value and the offset.

Claims

1. A method of determining a voltage of a cell of a battery pack of a vehicle, the method comprising:

determining an offset from balancing of the battery pack;

measuring a preliminary value of the voltage of the cell while the battery pack is being balanced; and

calculating, via a processor, an adjusted value of the voltage of the cell based on the preliminary value and the offset.

2. The method of claim 1, wherein the step of determining the offset comprises:

measuring a first value of the voltage prior to a beginning of the balancing of the battery pack;

measuring a second value of the voltage after the beginning of the balancing of the battery pack; and

calculating the offset using the first value and the second value.

3. The method of claim 2, wherein the step of calculating the offset comprises subtracting the second value from the first value.

4. The method of claim 2, wherein:

the step of measuring the first value comprises measuring the first value just prior to closing of a switch to begin the balancing of the battery pack; and

the step of measuring the second value comprises measuring the second value just after the closing of the switch to begin the balancing of the battery pack.

5. The method of claim 1, wherein multiple resistors are used for balancing the battery pack, and the step of calculating the adjusted value comprises:

calculating, via the processor, the adjusted value using the preliminary value, the offset, and resistance values for the multiple resistors.

6. The method of claim 1, further comprising:

measuring a plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a balancing event in which the preliminary value is measured; and

calculating a respective adjusted value of the voltage of the cell for each of the plurality of additional preliminary values using a respective one of the plurality of additional preliminary values and the offset.

7. The method of claim 6, further comprising:

measuring a new plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a second balancing event that is subsequent to the balancing event in which the preliminary value is measured;

determining a new offset from balancing of the battery pack for the second balancing event; and

calculating a new respective adjusted value of the voltage of the cell for each of the new plurality of additional preliminary values using a respective one of the new plurality of additional preliminary values and the new offset.

8. A system for determining a voltage of a cell of a battery pack of a vehicle, the system comprising:

a sensor configured to measure a preliminary value of the voltage of the cell while the battery pack is being balanced; and

a processor coupled to the sensor and configured to;

determine an offset from balancing of the battery pack; and

calculate an adjusted value of the voltage of the cell using the preliminary value and the offset.

9. The system of claim 8, wherein:

the sensor is configured to;

measure a first value of the voltage prior to a beginning of the balancing of the battery pack; and

measure a second value of the voltage after the beginning of the balancing of the battery pack; and

the processor is configured to calculate the offset using the first value and the second value.

10. The system of claim 9, wherein the processor is configured to calculate the offset by subtracting the second value from the first value.

11. The system of claim 9, wherein the sensor is configured to:

measure the first value just prior to closing of a switch to begin the balancing of the battery pack; and

measure the second value just after the closing of the switch to begin the balancing of the battery pack.

12. The system of claim 8, wherein multiple resistors are used for balancing the battery pack, and the processor is further configured to calculate the adjusted value using the preliminary value, the offset, and resistance values for the multiple resistors.

13. The system of claim 9, wherein:

the sensor is configured to measure a plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a balancing event in which the preliminary value is measured; and

the processor is configured to calculate a respective adjusted value of the voltage of the cell for each of the plurality of additional preliminary values using a respective one of the plurality of additional preliminary values and the offset.

14. The system of claim 13, wherein:

the sensor is configured to measure a new plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a second balancing event that is subsequent to the balancing event in which the preliminary value is measured; and

the processor is further configured to;

determine a new offset from balancing of the battery pack for the second balancing event; and

calculate a new respective adjusted value of the voltage of the cell for each of the new plurality of additional preliminary values using a respective one of the new plurality of additional preliminary values and the new offset.

15. A vehicle comprising:

a drive system including a battery pack; and

a control system for the battery pack, the control system comprising;

a sensor configured to measure a preliminary value of a voltage of a cell of the battery pack while the battery pack is being balanced; and

a processor coupled to the sensor and configured to;

determine an offset from balancing of the battery pack; and

calculate an adjusted value of the voltage of the cell using the preliminary value and the offset.

16. The vehicle of claim 15, wherein:

the sensor is configured to;

measure a first value of the voltage prior to a beginning of the balancing of the battery pack; and

measure a second value of the voltage after the beginning of the balancing of the battery pack; and

the processor is configured to calculate the offset using the first value and the second value.

17. The vehicle of claim 16, wherein the sensor is configured to:

measure the first value just prior to closing of a switch to begin the balancing of the battery pack; and

measure the second value just after the closing of the switch to begin the balancing of the battery pack.

18. The vehicle of claim 15, wherein multiple resistors are used for balancing the battery pack, and the processor is further configured to calculate the adjusted value using the preliminary value, the offset, and resistance values for the multiple resistors.

19. The vehicle of claim 15, wherein:

the sensor is configured to measure a plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a balancing event in which the preliminary value is measured; and

the processor is configured to calculate a respective adjusted value of the voltage of the cell for each of the plurality of additional preliminary values using a respective one of the plurality of additional preliminary values and the offset.

20. The vehicle of claim 19, wherein:

the sensor is configured to measure a new plurality of additional preliminary values of the voltage of the cell while the battery pack is being balanced, during a second balancing event that is subsequent to the balancing event in which the preliminary value is measured; and

the processor is further configured to;

determine a new offset from balancing of the battery pack for the second balancing event; and

calculate a new respective adjusted value of the voltage of the cell for each of the new plurality of additional preliminary values using a respective one of the new plurality of additional preliminary values and the new offset.