Energy storage control system and method

• US 9,469,212 B2
• Filed: 06/26/2015
• Issued: 10/18/2016
• 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:
  US14/752,403
• Publication Number:
  US 20150298572A1
• Time in Patent Office: 480 Days
• Field of Search: 701/22, 320/136, 702/63
• 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 computing system, comprising:

a processor and a memory storing instructions that are operable, when executed by the processor, to instruct the processor to perform a method to measure a state of an energy storage device during a rest period, wherein the energy storage device is configured to provide power over a power network, the method comprising;

establishing one or more rest periods of the energy storage device to enable an estimation of the state of the energy storage device by using a controller to maintain a reduced current across the energy storage device or by physically decoupling the energy storage device from the power network;

receiving information regarding the state of the energy storage device from a sensor during the one or more rest periods, and storing the information about the state of the energy storage device during the one or more rest periods;

determining a level of confidence in an accuracy of the information regarding the state of the energy storage device;

determining a level of disruption to normal operation of the power network that would be caused by maintaining the reduced current across the energy storage device or by decoupling the energy storage device from the power network, wherein the level of disruption is based at least in part on an ability of an electrical power producing unit to support a load amount when maintaining the reduced current across the energy storage device or decoupling the energy storage device; and

determining when to establish a new rest period to perform a new state measurement of the energy storage device based on both the level of confidence and the level of disruption.

2. The computing system of claim 1, the method comprising:

controlling the electrical power producing unit coupled to the power network to provide power to charge the energy storage device when coupled to the power network; and

determining when to establish the one or more rest periods based in part on an amount of electrical power produced by the electrical power producing unit to charge the energy storage device.

3. The computing system of claim 1, comprising a second energy storage device configured to provide additional current to the power network to operate a power network load.

4. The computing system of claim 1, wherein the method further comprises:

controlling a second energy storage device coupled to the power network to provide power to the power network; and

establishing the one or more rest periods of the energy storage device when the second energy storage device is capable of handling one or more load requirements of the power network.

5. The computing system of claim 1, the method comprising:

monitoring operation of the power producing unit; and

establishing the one or more rest periods when the power producing unit can handle an increased load resulting from decoupling the energy storage device from the power network.

6. The computing system of claim 1, the method comprising:

determining a length of time since a last measurement of the state of the energy storage device that is coupled to a regenerative power source; and

calculating a second level of confidence in a second accuracy of the last measurement of the state of the energy storage device based at least in part on the length of time since the last measurement of the energy storage device that is coupled to the regenerative power source.

7. The computing system of claim 1, wherein the level of disruption is based at least in part on changes to fuel economy, changes to vehicle power, potential aging of the energy storage device, or any combination thereof.

8. A system configured to provide power to a power network, comprising:

an energy storage device configured to couple to the power network;

a sensor coupled to the energy storage device to measure 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 configured to;

establish a time for the rest period based on a comparison of a first cost metric associated with minimization of disruption of the energy storage device and a second cost metric associated with a level of confidence in accuracy of a previous measurement of the state of the energy storage device;

receive operation data from the sensor during the rest period; and

estimate the state of the energy storage device based on the operation data.

9. The system of claim 8, wherein the operation data comprises battery data.

10. The system of claim 8, wherein the level is approximately zero.

11. The system of claim 8, comprising:

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

12. The system of claim 8, wherein the controller is configured to:

determine a length of time since the previous measurement of the state of the energy storage device; and

calculate the level of confidence in the accuracy of the previous measurement of the state of the energy storage device based at least in part on the length of time since the previous measurement of the state of the energy storage device.

13. The system of claim 8, wherein the controller is configured to:

store a preselected minimum level of confidence in an accuracy of a measurement of the state of the energy storage device;

calculate the level of confidence in the accuracy of the previous measurement of the state of the energy storage device;

compare the level of confidence in the accuracy of the previous measurement of the state energy storage device with the preselected minimum level of confidence;

disconnect the energy storage device based at least in part on a comparison of the level of confidence in the accuracy of the previous measurement and the preselected minimum level of confidence; and

determine an updated measurement of the state of the energy storage device after the energy storage device is disconnected.

14. A computer-implemented method to control an application of stored electrical power from an energy storage device to a power network, comprising:

establishing one or more rest periods during which a current from the energy storage device is reduced to a level that enables an estimation of a state of the energy storage device, wherein the one or more rest periods are established based on a comparison between a first cost metric associated with minimization of disruption of the energy storage device and a second cost metric associated with a level of confidence in accuracy of a previous measurement of the state of the energy storage device; and

measuring the state of the energy storage device during the one or more rest periods.

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

controlling a power producing unit coupled to the power network to provide power to the energy storage device when the energy storage device is coupled to the power network.

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

selectively providing additional current to the power network from an additional energy storage device to support a load amount during the one or more rest periods.

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

determining the one or more rest periods when a power producing unit can support a load amount during the rest periods of the energy storage device.

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

storing the previous measurement of the state of the energy storage device; and

storing the level of confidence of the previous measurement of the state of the energy storage device.

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

determining a length of time since the previous measurement of the state of the energy storage device occurred; and

calculating the level of confidence in the accuracy of the previous measurement based at least in part on the length of time since the previous measurement occurred.

20. The computer implemented method of claim 14, comprising:

storing a predetermined level of accuracy of a sensor that in operation measures information regarding the state of the energy storage device; and

calculating the level of confidence in the accuracy of the previous measurement of the state of the energy storage device based at least in part on the predetermined level of accuracy of the sensor.