Methods and apparatus for battery monitoring

• US 20080238432A1
• Filed: 02/29/2008
• Published: 10/02/2008
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Streit, Lawrence Craig, Botker, Tom Lloyd
• Granted Patent: US 8,130,000 B2
• Time in Patent Office: Days
• US Class Current: 324/434
• 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

Abstract

A battery monitoring system is provided to monitor a battery stack having multiple cells connected in series. The monitoring system includes monitor modules to monitor respective subsets of the cells of the battery stack, each monitor module, in response to one or more control signals, measuring cell voltages of the respective subset of cells and providing at least one readout signal that represents the sampled cell voltages, the monitor modules being electrically connected in a stack such that each monitor module is referenced to the voltage of the respective subset of cells, and the control signals and the readout signal are connected through the monitor modules of the stack, and a system control unit to provide the control signals to the monitor modules and to receive the readout signals from the monitor modules.

Claims

1. A monitor module to monitor a battery stack having multiple cells connected in series, comprising:

sampling circuits to sample cell voltages of corresponding cells of at least a subset of the cells of the battery stack;

a readout circuit to receive the sampled cell voltages of the corresponding cells of the subset of cells and to provide at least one readout signal that represents the sampled cell voltages; and

a module control unit to provide simultaneous sample commands to the sampling circuits and to provide sequential read commands to the sampling circuits, in response to control signals.

2. A monitor module as defined in claim 1, wherein each of the sampling circuits comprises a switched capacitor sampling circuit.

3. A monitor module as defined in claim 1, wherein the readout circuit is configured to receive a readout signal from an adjacent monitor module.

4. A monitor module as defined in claim 1, wherein the readout circuit is configured to provide the readout signal as an analog readout signal within the voltage of the monitor module.

5. A monitor module as defined in claim 1, wherein the module control unit receives control signals in the form of digital control signals within the voltage of the monitor module.

6. A monitor module as defined in claim 1, wherein the monitor module is powered by the subset of cells of the battery stack.

7. A monitor module as defined in claim 1, wherein the monitor module is configured to supply control signals to an adjacent monitor module.

8. A monitor module as defined in claim 1, wherein the readout circuit is configured to supply the readout signal to an adjacent monitor module or to a system control unit.

9. A monitor module as defined in claim 1, further comprising a cell balance circuit to monitor and control cell balance in the subset of cells.

10. A monitor module as defined in claim 1, further comprising a circuit to monitor a temperature sensor and to provide a readout signal representative of temperature.

11. A monitor module as defined in claim 1, wherein the monitor module is configured to perform at least one control function in response to a control signal.

12. A monitor module as defined in claim 1, wherein the monitor module is configured to operate in a low power mode during inactive periods.

13. A monitor module as defined in claim 1, wherein the monitor module is configured to perform one or more diagnostic operations to verify proper functioning.

14. A battery monitoring system to monitor a battery stack having multiple cells connected in series, comprising:

monitor modules to monitor respective subsets of the cells of the battery stack, each monitor module, in response to one or more control signals, measuring cell voltages of the respective subset of cells and providing at least one readout signal that represents the sampled cell voltages, the monitor modules being electrically connected in a stack such that each monitor module is referenced to the voltage of the respective subset of cells, and the control signals and the readout signal are connected through the monitor modules of the stack; and

a system control unit to provide the control signals to the monitor modules and to receive the readout signal from the monitor modules.

15. A battery monitoring system as defined in claim 14, wherein each of the monitor modules comprises:

sampling circuits to sample cell voltages of corresponding cells of the subset of cells;

a readout circuit to receive the sampled cell voltages of the corresponding cells of the subset of cells and to provide at least one readout signal that represents the sampled cell voltages; and

a module control unit to provide simultaneous sample commands to the sampling circuits and to provide sequential read commands to the sampling circuits and the readout circuit, in response to the control signals.

16. A battery monitoring system as defined in claim 14, wherein each monitor module is configured to supply the control signals to an adjacent monitor module in the stack.

17. A battery monitoring system as defined in claim 15, wherein each of the sampling circuits comprises a switched capacitor sampling circuit.

18. A battery monitoring system as defined in claim 14, wherein each of the monitor modules is powered by the respective subset of cells of the battery stack.

19. A battery monitoring system as defined in claim 14, wherein each of the monitor modules is configured to perform one or more control functions in response to control signals.

20. A battery monitoring system as defined in claim 14, wherein each of the monitor modules is configured to operate in a low power mode during inactive periods.

21. A battery monitoring system as defined in claim 14, wherein each of the monitor modules is configured to perform one or more diagnostic operations to verify proper functioning.

22. A battery monitoring system as defined in claim 14, wherein the readout signal comprises a differential current readout signal that represents sampled cell voltages.

23. A battery monitoring system as defined in claim 14, wherein the readout signal comprises an analog readout signal that represents sampled cell voltages.

24. A method for monitoring a battery stack having multiple cells connected in series, comprising:

providing monitor modules to monitor respective subsets of the cells of the battery stack;

referencing each monitor module to the voltage of the respective subset of cells; and

connecting control signals and readout signals serially through the monitor modules.

25. A method as defined in claim 24, wherein connecting control signals and readout signals serially through the monitor modules comprises supplying differential current readout signals representative of monitored voltages of respective cells of the battery stack.

26. A method as defined in claim 24, wherein connecting control signals and readout signals serially through the monitor modules comprises supplying analog readout signals representative of monitored voltages of respective cells of the battery stack.

27. A method as defined in claim 24, further comprising controlling cell balance in the cells of the battery stack.

28. A method as defined in claim 24, further comprising performing one or more control functions in response to the control signals.

29. A method as defined in claim 24, further comprising operating each monitor module in a low power mode during inactive periods.

30. A method for monitoring a battery stack having multiple cells connected in series, comprising:

providing one or more monitor modules to monitor respective subsets of the cells of the battery stack;

simultaneously sampling cell voltages of the cells of the battery stack with the one or more monitor modules; and

sequentially reading the sampled cell voltages of the cells of the battery stack and providing at least one readout signal that represents the sampled cell voltages.

31. A method as defined in claim 30, wherein simultaneously sampling cell voltages comprises sampling cell voltages with a switched capacitor sampling circuit.

32. A method as defined in claim 31, wherein providing at least one readout signal comprises providing a differential current readout signal that represents sampled cell voltages.

33. A method as defined in claim 30, wherein providing at least one readout signal comprises providing an analog readout signal that represents sampled cell voltages.

34. A method as defined in claim 30, further comprising controlling cell balance of the cells of the battery stack.

35. A method as defined in claim 30, further comprising operating the one or more monitor modules in a low power mode during inactive periods.