BATTERY SYSTEM AND MANAGEMENT METHOD

• US 20080303527A1
• Filed: 05/08/2008
• Published: 12/11/2008
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: C&C Power Incorporated
• Original Assignee: C&C Power Incorporated
• Inventors: Conrardy, N. William, Fechalos, William
• Granted Patent: US 8,558,508 B2
• Time in Patent Office: Days
• US Class Current: 324/426
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC

Abstract

A system and method for monitoring the status of a system of battery strings is described. The system includes a current sensor for each of the battery strings, and a controller configured to compute the average current from the measured currents. The state of the battery system is determined as being fully charged, discharging or charging, and the individual battery string currents are compared with the average measured current to determine if the currents are within a threshold value. An alarm indication is provided when one or more of the currents exceeds a threshold difference. The system may provide a local indication of status and may also interface with a communications network to provide for remote monitoring.

Claims

1. A system for monitoring a battery system, comprising:

a plurality of current sensors, at least one of the plurality of current sensors disposed so as to measure a current value of a battery string of a plurality of battery strings;

a controller; and

wherein the controller is configured to compare the current value with an average value of the current values of a the plurality of battery strings, and provide an alarm indication when the current value deviates from the average current value by more than a threshold value.

2. The system of claim 1, wherein a state of the battery system when the current value is compared with the average current value is determined to be one of a fully-charged state, a discharging state or a charging state.

3. The system of claim 2, where the charging state exists for a time duration after the end of the discharging state, the time duration being proportional to a time duration of the discharging state.

4. The system of claim 2, wherein the current value measured in the fully-charged state is a float current value.

5. The system of claim 4, wherein a battery string comprises two or more batteries connected in series.

6. The system of claim 1, wherein the threshold value depends on a state of the battery system.

7. The system of claim 6, wherein the threshold value is a percentage of the average current for the state of the battery system.

8. The system of claim 6, wherein the threshold comprises at least one of a warning threshold or a fault threshold.

9. The system of claim 1, further comprising at least one of a voltmeter or a temperature sensor.

10. The system of claim 1, wherein the controller communicates with a system controller using a local communications network.

11. The system of claim 10, wherein the local communications network is an Ethernet.

12. The system of claim 10, wherein the local communications network is a wireless network.

13. The system of claim 12, wherein the wireless network conforms to one or more of IEEE 802.11b or IEEE 802.11g.

14. The system of claim 9, wherein at least one of the controller or a system controller is adapted to compute the average current value measured by at least a group of the plurality of current sensors, to determine a state of the battery system, and to compare the computed deviation with the threshold value.

15. The system of claim 9, wherein at least one of the controller or a system controller communicates with a remotely-located controller using a communications network and reports at least an occurrence of the alarm indication.

16. The system of claim 1, wherein the controller is the system controller.

17. The system of claim 1, wherein the alarm indication is displayed by an indicator device.

18. The system of claim 1 wherein the controller communicates with a remotely-located controller using a communications network and reports at least an occurrence of the alarm indication.

19. The system of claim 18, wherein the communications network is the Internet.

20. The system of claim 1, wherein a remotely-located controller receives a report of an alarm indication, and communicates the alarm indication to a user.

21. The system of claim 20, wherein the communication is by a graphical user interface (GUI).

22. The system of claim 20, wherein the communication is by an audible indication.

23. The system of claim 22, wherein the communication is by synthesized speech.

24. The system of claim 1, wherein the battery string is a plurality of rechargable batteries connected in series, and the plurality of battery strings are connected in parallel to supply electrical power to a load connectable to the system.

25. The system of claim 1, wherein the current sensor is a Hall effect device.

26. The system of claim 25, wherein the current sensor is a closed-loop device.

27. The system of claim 25, wherein a bus-bar shunt is used to modify a current sensing sensitivity of the current sensor.

28. The system of claim 27, wherein he bus-bar shunt decreases the current sensing sensitivity by a factor of 4.

29. A battery system, comprising:

a plurality of battery strings connected in parallel;

current sensors disposed to measure a current value in each of the plurality of battery strings;

a controller configured to receive at least two of the measured current values, to compute an average current value, and to compare the received measured current values to the average current value.

30. The system of claim 29, wherein a threshold value is established as a variation limit with respect to the average current value, and an indication is provided if any of the measured currents exceed the threshold value.

31. The system of claim 30, wherein the threshold value is a percentage of the average current.

32. The system of claim 30, wherein the threshold value is a numerical value.

33. The system of claim 30, wherein the threshold value comprises an upper threshold value and a lower threshold, and a magnitude of the upper and threshold values are unequal.

34. The system of claim 30, wherein the threshold value is dependent on a system state.

35. The system of claim 34, wherein the system state is one of charging, discharging, or fully charged.

36. The system of claim 34, wherein the discharging state is such that power is being delivered from the battery strings to a load connectable to the battery system.

37. The system of claim 36, wherein the charging state is such that power is being supplied from a source of direct current power to at least the battery strings, and the battery string is not fully charged.

38. The system of claim 29, further comprising an alternating-current-to-direct-current converter, configured to receive power from an external source and provide direct current at least one of the plurality of battery strings or a load.

39. A method of managing a battery system, the method comprising:

measuring a current of each of a plurality of battery strings;

determining an operating state of the battery system using at least the measured currents;

computing an average current of the measured currents of the plurality of battery strings;

determining a difference value between the current measured for each of the plurality of battery strings and the average measured current;

comparing the difference value with a threshold value; and

providing an alarm indication when the difference value exceeds the threshold value for the determined operating state of the battery system.

40. The method of claim 39, wherein the alarm indication is transmitted over a communications network.

41. The method of claim 39, where the alarm indication is received by a remotely-located controller interfaced with a communications network.

42. The method of claim 39, wherein the threshold value is a percentage of the average current for the operating state.

43. The method of claim 39, wherein multiple threshold values exist for at least one state, and a type of the alarm indication depends on the threshold value exceeded.

44. The method of claim 39, wherein the threshold value may have a different value for the measured current greater than the average current and for the measured current less than the average current.

45. The method of claim 39, wherein the state of the battery system is determined to be one of fully charged, discharging or charging, based on at least the magnitude or sense of the measured current for one or more battery strings.

46. The method of claim 45, wherein when the system is in a discharging state, a subsequent charging state has a time duration which is a multiple of the time duration of the discharging state, and the fully charged state is not determined until the completion of the charging state.

47. The method of claim 46, where the time duration of a plurality of discharging states is cumulative, and the duration of the charging state is a multiple of the cumulative discharging time duration.

48. A software program product, stored in a computer-readable medium, enabling a computer to perform the steps in a method, the method comprising:

measuring a current value in a plurality of battery strings in a battery system;

computing an average of the current values;

determining a deviation of a current value of the current values from the average current;

determining an operating state of the battery system;

comparing a deviation of the current value from the average current of the current values with a threshold value for the determined operating state; and

generating an alarm indication when the deviation exceeds the threshold value.