Multiple battery cell monitor having shared control lines and balance switch

Patent metadata

Field	Value
Publication number	US-10326287-B2
Application number	US-201715650891-A
Country	US
Kind code	B2
Filing date	Jul 15, 2017
Priority date	Mar 27, 2017
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

Battery systems that can monitor and control multiple battery cells in electronic devices. One embodiment provides a battery system having multiple battery cells controlled by a single battery controller. Each battery cell is connected to a first end of a control path, a second end of the control path is connected to either a positive terminal or a negative terminal of the battery system. Each control path includes a charge control transistor that allows or prevents charging of a battery cell, a discharge control transistor that allows or prevents discharging of a battery cell, and a current sense resistor to sense currents into or out of a battery cell. The charge control transistor and the discharge control transistor can be controlled by control outputs provided by the battery controller. The battery controller also includes a balance switch to provide a low-impedance path between battery cells to reduce offset voltages between them.

First claim

What is claimed is:

1. A battery system comprising:
a first battery cell having a first terminal and a second terminal;
a second battery cell having a first terminal and a second terminal, the first terminal of the second battery cell coupled to the first terminal of the first battery cell;
a battery controller;
a first control path coupled between the second terminal of the first battery cell and a first terminal of the battery system, the first control path comprising:
a first sense resistor;
a first discharge control transistor; and
a first charge control transistor; and

a second control path coupled between the second terminal of the second battery cell and the first terminal of the battery system, the second control path comprising:
a second sense resistor;
a second discharge control transistor; and
a second charge control transistor,

where a control electrode of the first discharge control transistor is coupled to a control electrode of the second discharge control transistor and to a discharge control output of the battery controller, and
where a control electrode of the first charge control transistor is coupled to a control electrode of the second charge control transistor and to a charge control output of the battery controller.

2. The battery system of claim 1 wherein the first battery cell and the second battery cell have different form factors.

3. The battery system of claim 1 wherein the first battery cell and the second battery cell have different capacities.

4. The battery system of claim 1 wherein the first battery cell and the second battery cell have different form factors and different capacities.

5. The battery system of claim 2 wherein the first discharge control transistor, the second discharge control transistor, the first charge control transistor, and the second charge control transistor are N-channel field-effect transistors.

6. The battery system of claim 2 wherein the first discharge control transistor, the second discharge control transistor, the first charge control transistor, and the second charge control transistor are P-channel field-effect transistors.

7. The battery system of claim 2 wherein the first control path is coupled between the second terminal of the first battery cell and a negative terminal of the battery system and the second control path is coupled between the second terminal of the second battery cell and the negative terminal of the battery system.

8. The battery system of claim 2 further comprising a first temperature sensor near the first battery cell and a second temperature sensor near the second battery cell, wherein the first temperature sensor and the second temperature sensor are coupled to the battery controller.

9. The battery system of claim 8 wherein responsive to either the first temperature sensor or the second temperature sensor detecting a temperature above a temperature threshold, the battery controller prevents charging of the first battery cell and the second battery cell.

10. The battery system of claim 2 further comprising a balance switch to provide a low impedance path from the second terminal of the first battery cell to the second terminal of the second battery cell in response to either the first discharge control transistor and the second discharge control transistor or the first charge control transistor and the second charge control transistor being off and an absolute value of a voltage difference between the first battery cell and the second battery cell being greater than a first threshold voltage.

11. The battery system of claim 10 wherein the balance switch comprises a transistor coupled between the second terminal of the first battery cell and the second terminal of the second battery cell.

12. The battery system of claim 10 wherein the balance switch comprises a series combination of a first transistor and a second transistor coupled between the second terminal of the first battery cell and the second terminal of the second battery cell.

13. The battery system of claim 12 further comprising a window comparator having a first input coupled to the second terminal of the first battery cell, a second input coupled to the second terminal of the second battery cell, and a third input coupled to receive the first threshold voltage.

14. The battery system of claim 13 wherein the series combination of a first transistor and a second transistor is formed on an integrated circuit with the battery controller.

15. The battery system of claim 13 wherein the series combination of a first transistor and a second transistor is located off an integrated circuit comprising the battery controller.

16. The battery system of claim 12 wherein the series combination of a first transistor and a second transistor is located off an integrated circuit comprising the battery controller.

17. The battery system of claim 2 wherein a body diode of the first charge control transistor provides a discharge path for the first battery cell when the first charge control transistor is off.

18. A battery system comprising:
a first battery cell having a first terminal and a second terminal;
a second battery cell having a first terminal and a second terminal, the first terminal of the second battery cell coupled to the first terminal of the first battery cell; and
a battery controller comprising:
a balance switch to provide a low impedance path from the second terminal of the first battery cell to the second terminal of the second battery cell in response to either a first discharge control transistor and a second discharge control transistor or a first charge control transistor and a second charge control transistor being off and an absolute value of a voltage difference between the first battery cell and the second battery cell being greater than a first voltage threshold.

19. The battery system of claim 18 wherein the first battery cell and the second battery cell have different capacities and different form factors.

20. The battery system of claim 19 wherein the balance switch comprises a series combination of a first transistor and a second transistor coupled between the second terminal of the first battery cell and the second terminal of the second battery cell.

Assignees

• Apple Inc

Inventors

• Hoyt Robert J
• Heathershaw Todd D

Classifications

• H02J7/64

  against overvoltage · CPC title

• H02J7/63

  against overdischarge · CPC title

• H02J7/62

  against overcurrent · CPC title

• H02J7/575

  Parallel/serial switching of connection of batteries to charge or load circuit · CPC title

• H02J7/80

  including monitoring or indicating arrangements · CPC title