Energy Storage Control System and Method

• US 20140207318A1
• Filed: 08/29/2013
• Published: 07/24/2014
• 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.
• Granted Patent: US 9,085,238 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• 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 by optimizing between minimization of disruption to normal vehicle operation and a need to update a measurement of the state of the energy storage device.

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 for providing 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 for providing 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.

8. The system of claim 1, wherein the sensor has a predetermined level of accuracy, and wherein the controller stores the predetermined level of accuracy of the sensor, and calculates a level of confidence in the accuracy of a last state measurement of the energy storage device based at least in part by the predetermined level of accuracy of the sensor.

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, and

disconnect the energy storage device to enable the updated state measurement of the energy storage device based at least in part on the comparison.

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,

compare the measurement of a last state measurement of the energy storage device with a 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 determination and the comparison.

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

12. 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 by optimizing between minimization of disruption to normal vehicle operation and a need to update a measurement of the state of the energy storage device; and

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

13. The computer-implemented method of claim 12, further comprising:

controlling a power producing unit connected to the power network for providing produced power to the energy storage device when connected to the power network.

14. The computer-implemented method of claim 12, further comprising:

selectively providing additional current to the power network from an additional energy storage device for operation of the power network load.

15. The computer-implemented method of claim 12, 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.

16. The computer-implemented method of claim 12, further comprising:

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

17. The computer-implemented method of claim 12, 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 stored results of the state measurement of the energy storage device.

18. The computer-implemented method of claim 12, further comprising:

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

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

19. The computer implemented method of claim 12, further comprising:

storing a predetermined level of accuracy of the sensor; and

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

20. The computer-implemented method of claim 12, further comprising:

storing a preselected minimum level of confidence in a state measurement;

calculating a level of confidence in a measurement obtained from a last state measurement;

comparing the measurement of the last occurrence of a state measurement with the preselected minimum level of confidence; and

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

21. The computer-implemented method of claim 12, further comprising:

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

comparing the measurement of a last occurrence of a state measurement with a preselected minimum level of confidence; and

disconnecting the energy storage device to enable a new state measurement based in response to both the determining means and the comparing means.

22. A computing system, comprising:

a processing unit and a storage device storing instructions that are operable, when executed by the processing unit, to cause the processing unit to perform a method for measuring a state of an energy storage device during a rest period, wherein the energy storage device provides power over a vehicle power network, the method comprising;

establishing rest periods during which a current through the energy storage device is reduced to a level that permits an estimation of a state of the energy storage device, wherein reducing the current can be accomplished by physically disconnecting the energy storage device from the vehicle power network, or by using a controller to maintain the reduced current is disconnected from the power network for operation of a power network load to reduce current through the energy storage device to near zero to measure the state of the energy storage device;

receiving information regarding a state of the energy storage device from a sensor during the rest period, and storing the information about the energy storage device;

determining a level of confidence in the accuracy of the stored information regarding the state;

evaluating a level of disruption to normal operation that would be caused by disconnection of the energy storage device; and

determining, based upon both the level of confidence in the accuracy of the stored state and the level of disruption to the strategy that disconnection of the energy storage device would cause, when to establish a rest period for a new state measurement and storage of a new state of the energy storage device.

23. The computing system of claim 22, further comprising:

controlling an electrical power producing unit connected to the power network for providing produced power to charge the energy storage device when connected to the power network; and

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

24. The computing system of claim 22, wherein the energy storage device is a first energy storage device and selectively providing additional current to the power network from a second storage device for operation of the power network load.

25. The computing system of claim 22, wherein the energy storage device is a first energy storage device and wherein the method further comprises:

controlling a second storage device connected to the power network; and

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

26. The computing system of claim 22, further comprising:

monitoring operation of a power producing unit; and

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

27. The computing system of claim 22, further comprising:

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

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

28. 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.

29. The computer-implemented method of claim 28, 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.

30. 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.