Charge control circuit for a battery

• US 20040051505A1
• Filed: 09/13/2002
• Published: 03/18/2004
• Est. Priority Date: 09/13/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Becker-Irvin, Craig H.
• Granted Patent: US 6,759,829 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

A charging circuit (28) particularly suited for use in a satellite (20) has a battery cell (32). A voltage sensor (36) is coupled to the battery for generating a cell voltage signal. A current sensor (34) is coupled to the battery cell (32) and generates a cell charge current signal. A controller (38) is coupled to the voltage sensor (36) and the current sensor (34). The controller (38) determines a compensated voltage in response to the cell voltage signal and the charge current signal and controls the charging of the battery cell (32) in response to the compensated voltage.

Claims

1. A charging circuit for a battery comprising:

a voltage sensor coupled to the battery for generating a cell voltage signal;

a current sensor coupled to the battery for generating a cell charge current signal; and

a controller coupled to said voltage sensor and said current sensor, said controller determining a compensated battery cell voltage in response to the cell voltage signal and the charge current signal, said controller charging of the battery in response to the compensated voltage signal.

2. A charging circuit as recited in claim 1 wherein said controller controls charging of the battery in response to the cell voltage signal, the charge current signal and a direct current resistance.

3. A charging circuit as recited in claim 2 wherein the direct current resistance includes harness resistance.

4. A charging circuit as recited in claim 1 wherein the controller controls charging the battery in response to reprogrammable thresholds.

5. A charging circuit as recited in claim 1 wherein the battery comprises a lithium ion battery.

6. A charging circuit as recited in claim 1 wherein the compensated battery cell voltage is determined by V_measured−

I_cell×

R_cell+V_o where V_measured is the cell voltage signal, R_cell is the DC resistance and V_o is an offset voltage.

7. A satellite comprising:

a battery;

a charging circuit coupled to the battery;

a voltage sensor coupled to the battery for generating a cell voltage signal;

a current sensor coupled to the battery for generating a cell charge current signal; and

a controller coupled to said voltage sensor and said current sensor, said controller determining a compensated battery cell voltage in response to the cell voltage signal and the charge current signal, said controller charging of the battery in response to the compensated voltage signal.

8. A satellite as recited in claim 7 wherein said battery comprises a lithium ion battery.

9. A satellite as recited in claim 7 wherein the compensated battery cell voltage is determined by the formula

10. A satellite as recited in claim 7 wherein the offset voltage is zero.

11. A satellite as recited in claim 7 wherein said battery comprises a plurality of cells.

12. A satellite as recited in claim 7 wherein said controller controls charging of the battery in response to the cell voltage signal, the charge current signal and a direct current resistance.

13. A satellite as recited in claim 7 wherein the direct current resistance includes harness resistance.

14. A satellite as recited in claim 7 wherein the controller controls charging the battery in response to reprogrammable thresholds.

15. A satellite as recited in claim 8 wherein said controller comprises a voltage processor and a battery charge unit.

16. A method for charging a battery comprises:

measuring a cell voltage;

measuring a cell charge current;

determining a compensated voltage in response to the cell voltage and the cell charge current;

comparing the compensated voltage to a threshold;

discontinuing the cell charge current when the compensated voltage exceeds the threshold.

17. A method as recited in claim 16 wherein determining a compensated voltage comprises determining a compensated voltage in response to direct current cell resistance.

18. A method as recited in claim 16 wherein determining a compensated voltage comprises determining a compensated voltage in response to a total direct current resistance of a multiple cell battery.

19. A method as recited in claim 16 wherein said battery comprises a lithium ion battery.

20. A method as recited in claim 16 wherein said threshold is reprogrammable.