Energy storage control system and method

• US 9,085,238 B2
• Filed: 08/29/2013
• Issued: 07/21/2015
• Est. Priority Date: 01/11/2013
• Status: Active Grant

• Current Assignee: CPS Technology Holdings, LLC
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Sisk, Brian C., Watson, Thomas M.
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): PAIGE, TYLER D
• Application Number:
  US14/014,270
• Publication Number:
  US 20140207318A1
• Time in Patent Office: 691 Days
• Field of Search: 701/22, 320/132, 320/134, 324/426
• US Class Current: 1/1
• CPC Class Codes: B60L 1/00 Supplying electric power to auxiliary equipment of vehicles circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/16 responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A system for providing power to a power network includes an energy storage device connected to the power network, a sensor connected with the energy storage device for measuring a state of the energy storage device during a rest period, which corresponds to a time span during which a current through the energy storage device is reduced to a level that enables an estimation of a state of the energy storage device. The system further includes a controller connected to the sensor for measuring a state of the energy storage device. The controller selectively establishes rest periods for the energy storage device. The rest periods are established by optimizing between minimization of disruption to normal operation and a need to update a measurement of the state of the energy storage device.

Claims

1. A system for providing power to a vehicle power network, comprising:

an energy storage device connected to the power network;

a sensor connected to the energy storage device for measuring a state of the energy storage device during a rest period, wherein the rest period corresponds to a time span during which a current through the energy storage device is reduced to a level that enables an estimation of a state of the energy storage device; and

a controller that receives data from the sensor and estimates the state of the energy storage device based on data, wherein the controller establishes the rest period based on a comparison between a first cost metric associated with obtaining a new measurement of the energy storage device and a second cost metric associated with a disruption of normal vehicle operation during the rest period.

2. The system of claim 1, wherein the data is battery data.

3. The system of claim 1, wherein the data is vehicle data external to the battery.

4. The system of claim 1, wherein the current level that enables the state estimation is approximately zero.

5. The system of claim 1, further comprising:

an additional sensor configured to receive information about a condition of a power producing unit to the controller, wherein the controller utilizes the information from the power producing unit to establish additional rest periods when the power production unit can handle an increased load resulting from a disconnection of the energy storage device from the power network.

6. The system of claim 1, further comprising:

an additional energy storage device connected to the power network configured to provide additional current to the power network for operation of a power network load; and

an additional sensor that receives data from the sensor and measures a state of the additional energy storage device when the additional energy storage device has been disconnected from the power network by the controller to reduce stored electrical current to near-zero during rest periods for the additional energy storage device, the controller establishing additional rest periods for the energy storage device when the additional energy storage device is capable of handling load requirements of the power network.

7. The system of claim 1, wherein the controller determines a length of time since a last state measurement of the energy storage device, and calculates a level of confidence in the accuracy of the last state measurement of the energy storage device based at least in part on the length of time since the last measurement of the state of the energy storage device, and wherein the first cost metric comprises the level of confidence in the accuracy of the last state measurement.

8. The system of claim 1, wherein the sensor is associated with a predetermined level of accuracy, and wherein the controller stores the predetermined level of accuracy of the sensor in a memory, and calculates a level of confidence in the accuracy of a last state measurement of the energy storage device based at least in part on the predetermined level of accuracy of the sensor, and wherein the first cost metric comprises the level of confidence in the accuracy of the last state measurement.

9. The system of claim 1, wherein the controller is programmed to:

store a preselected minimum level of confidence in an energy storage device state measurement,

calculate a level of confidence in a measurement obtained from a last state measurement of the energy storage device,

compare the measurement of the last energy storage device state measurement with the preselected minimum level of confidence,

disconnect the energy storage device based at least in part on the comparison, and

enable the updated state measurement of the energy storage device.

10. The system of claim 1, wherein the controller is programmed to:

determine whether setting the energy storage device current to the level that enables an estimation of the state will have a negative impact on the normal operation,

determine at least a portion of the second cost metric based on whether the state will have a negative impact on the normal operation,

compare the measurement of a last state measurement of the energy storage device with a preselected minimum level of confidence,

determine at least a portion of the first cost metric based on a comparison of the last state measurement of the energy storage device with the preselected minimum level of confidence, and

disconnect the energy storage device to enable a new state measurement of the energy storage device based on both the first cost metric and the second cost metric.

11. The system of claim 1, wherein the power network is a vehicle power network.

12. The system of claim 1, wherein the state of the energy storage device comprises a state of charge.

13. A computer-implemented method for controlling the application of stored electrical power to a vehicle power network, wherein an energy storage device is connected to the vehicle power network to provide stored power electrical current to the power network for operation of a power network load, the method comprising:

establishing energy storage device rest periods during which a current through the energy storage device is reduced to a level that enables an estimation of a state of the energy storage device, wherein the rest periods are established based on a comparison between a first cost metric associated with obtaining a new measurement of the energy storage device and a second cost metric associated with a disruption of normal vehicle operation during the rest period; and

measuring a state of the energy storage device during the rest periods.

14. The computer-implemented method of claim 13, further comprising:

controlling a power producing unit connected to the power network to provide power from a power producing unit to the energy storage device when connected to the power network.

15. The computer-implemented method of claim 13, further comprising:

selectively providing additional current to the power network from an additional energy storage device to operate the power network load.

16. The computer-implemented method of claim 13, wherein the energy storage device is a first energy storage device, and the method further comprises:

providing power to the power network from a second energy storage device; and

establishing the rest periods for the first energy storage device when the second energy storage device is capable of handling load requirements of the power network.

17. The computer-implemented method of claim 13, further comprising:

establishing the rest periods when a power producing unit can handle an increased load resulting from disconnection of the energy storage device.

18. The computer-implemented method of claim 13, further comprising:

storing a most recent measurement by a sensor of the state of the energy storage device; and

storing a level of confidence of the most recent measurement of the energy storage device.

19. The computer-implemented method of claim 13, further comprising:

determining a length of time since a last state measurement; and

calculating a level of confidence in an accuracy of the last state measurement based at least in part on a length of time since the last state measurement was measured.

20. The computer implemented method of claim 13, further comprising:

storing a predetermined level of accuracy of the sensor; and

calculating a level of confidence in the predetermined level of accuracy of a last state measurement based at least in part on the predetermined level of accuracy of the sensor.

21. The computer-implemented method of claim 13, further comprising:

storing a preselected minimum level of confidence in a state measurement of the energy storage device;

calculating a level of confidence in a measurement obtained from a last state measurement of the energy storage device;

comparing the measurement of the last state measurement of the energy storage device with the preselected minimum level of confidence; and

disconnecting the energy storage device to enable a new state measurement of the energy storage device based at least in part on said comparison.

22. The computer-implemented method of claim 13, further comprising:

determining whether setting a current of the energy storage device to the level that enables estimation of the state of the energy storage system will have a negative impact on the normal vehicle operation based on the second cost metric;

comparing a measurement of a last occurrence of a state measurement with a preselected minimum level of confidence based on the first cost metric; and

disconnecting the energy storage device to enable a new state measurement based in response to both the first cost metric and the second cost metric.

23. The computer-implemented method of claim 13, wherein the state of the energy storage device comprises a state of charge.

24. A computer-implemented method for controlling provision of power to a power network, comprising:

providing electrical current to the power network from an energy storage device for operation of a power network load;

reducing the current through the energy storage device with a switch to a level that enables an estimation of a state of the energy storage device for a rest period; and

measuring a state of the energy storage device within a certain level of accuracy during the rest period.

25. The computer-implemented method of claim 24, further comprising:

establishing a strategy of operation;

monitoring operation of a power producing unit;

storing a last measurement of a state;

establishing a declining level of confidence in the last measurement of the state; and

establishing when the rest periods occur by optimizing between minimization of disruption to the normal operation and the declining level of confidence in the last measurement of the state.

26. The computer-implemented method of claim 24, wherein the state of the energy storage device comprises a state of charge.

27. A system for providing power to a vehicle power network, comprising:

a first energy storage device connected to the vehicle power network;

a second energy storage device connected to the vehicle power network;

a controller that establishes rest periods for the each of the first energy storage device and the second energy storage device during which current through the respective energy storage device is reduced to a level that enables an estimation of the state of the energy storage device, the rest periods established according to a strategy so as to not adversely affect the normal operation of the vehicle.

28. The system of claim 27, wherein the state of the energy storage device comprises a state of charge.