Methods and system for a battery

Patent metadata

Field	Value
Publication number	US-11233257-B2
Application number	US-201815965673-A
Country	US
Kind code	B2
Filing date	Apr 27, 2018
Priority date	Apr 28, 2017
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

Systems and methods for operating a redox flow battery system may include switching the redox flow battery system to an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode; in response to switching to the idle mode, repeatedly cycling operation of an electrolyte pump between an idling threshold flow rate less than a charging threshold flow rate and a deactivation threshold flow rate; and in response to switching to the charging mode, maintaining operation of the electrolyte pump at the charging threshold flow rate greater than the idling threshold flow rate. In this way, a responsiveness of the redox flow battery system to charging and discharging commands can be maintained while in idle, while reducing parasitic pumping losses due to pumping and heating, and reducing shunt current losses.

First claim

The invention claimed is:

1. A method of operating a redox flow battery system, the method comprising:
switching the redox flow battery system to an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode,
in response to switching to the idle mode,
repeatedly cycling operation of an electrolyte pump between an idling threshold flow rate less than a charging threshold flow rate and a deactivation threshold flow rate, each of the idling threshold flow rate and the deactivation threshold flow rate being non-zero, and

in response to switching to the charging mode,
maintaining operation of the electrolyte pump at the charging threshold flow rate greater than the idling threshold flow rate.

2. The method of claim 1 , further comprising, in response to switching to the discharge mode, maintaining operation of the electrolyte pump at a discharge threshold flow rate greater than the idling threshold flow rate.

3. The method of claim 2 , wherein operation of the electrolyte pump at the deactivation threshold flow rate is maintained for at least a first threshold duration, operation of the electrolyte pump at the idling threshold flow rate is maintained for at least a second threshold duration, and the first threshold duration is greater than the second threshold duration.

4. The method of claim 3 , wherein the second threshold duration is less than 20% of the first threshold duration.

5. The method of claim 4 , wherein the idling threshold flow rate is adjusted higher in response to an anticipated load demand of the redox flow battery system being higher, and the idling threshold flow rate is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower.

6. The method of claim 5 , wherein the first threshold duration is adjusted lower in response to the anticipated load demand of the redox flow battery system being higher, and the first threshold duration is adjusted higher in response to the anticipated load demand of the redox flow battery system being lower.

7. The method of claim 6 , wherein the second threshold duration is adjusted higher in response to the anticipated load demand of the redox flow battery system being higher, and the second threshold duration is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower.

8. A method of operating a redox flow battery system, the method comprising:
operating the redox flow battery system in an idle mode during a condition when the redox flow battery system is operating outside of a charging mode and outside of a discharge mode while a DC current remains zero;
during operation in the idle mode, repeatedly cycling operation of at least one electrolyte pump between an active state and an inactive state, wherein the active state comprises pumping electrolyte at an idling threshold flow rate less than a charging threshold flow rate, and the inactive state comprises deactivating the at least one electrolyte pump;
in response to switching to the discharge mode, maintaining operation of the at least one electrolyte pump at a discharge threshold flow rate; and
in response to switching to the charging mode, maintaining operation of the at least one electrolyte pump at the charging threshold flow rate,
wherein cycling operation of the at least one electrolyte pump between the active state and the inactive state includes, switching from the active state to the inactive state in response to a power module voltage increasing above a second threshold voltage, and switching from the inactive state to the active state in response to the power module voltage decreasing below a first threshold voltage, the first threshold voltage being less than the second threshold voltage.

9. The method of claim 8 , wherein the idling threshold flow rate is adjusted higher in response to an anticipated load demand of the redox flow battery system being higher, and the idling threshold flow rate is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower.

10. The method of claim 9 , wherein the first threshold voltage is adjusted higher in response to the anticipated load demand of the redox flow battery system being higher, and the first threshold voltage is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower.

11. The method of claim 10 , wherein the second threshold voltage is adjusted higher in response to the anticipated load demand of the redox flow battery system being higher, and the second threshold voltage is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower.

12. A redox flow battery system, comprising:
a power module, including a plurality of redox flow battery cell stacks, each of the plurality of redox flow battery cell stacks including a respective redox flow battery cell having a positive electrolyte chamber and a negative electrolyte chamber;
an electrolyte pump capable of delivering electrolyte from an electrolyte tank to the power module;
and a power control system with a controller including instructions thereon, the instructions executable to:
switch the redox flow battery system to an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode,
in response to switching to the idle mode, repeatedly cycle operation of the electrolyte pump between an idling threshold flow rate less than a charging threshold flow rate and a deactivation threshold flow rate, each of the idling threshold flow rate and the deactivation threshold flow rate being non-zero,
and, in response to switching to the charging mode, maintain operation of the electrolyte pump at the charging threshold flow rate, and flow electrolyte unequally to the positive and negative electrolyte chambers of each respective redox flow battery cell of the plurality of redox flow battery cell stacks.

13. The system of claim 12 , further comprising a heater thermally coupled to the electrolyte, wherein the instructions are further executable to reduce an electrolyte temperature to an idling threshold temperature in response to switching to the idle mode.

14. The system of claim 13 , wherein the idling threshold temperature is increased in response to an anticipated load demand of the redox flow battery system being higher, and the idling threshold temperature is decreased in response to the anticipated load demand of the redox flow battery system being lower.

15. The system of claim 14 , wherein power electronics are deactivated in response to switching to the idle mode.

16. The system of claim 15 , wherein the idling threshold temperature corresponds to a temperature below which electrolyte precipitation occurs.

17. The system of claim 16 , wherein the idling threshold temperature is less than the electrolyte temperature during the charging and discharge modes.

18. The method of claim 8 , wherein deactivating the at least one electrolyte pump comprises deactivating a sufficient number of electrolyte pumps to stop circulation of electrolyte to and from redox flow battery cells of the redox flow battery system.

Assignees

• Ess Technology Inc

Inventors

• Song Yang
• Doremus Evan

Classifications

• H01M8/18 Primary

  Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/04753 Primary

  of fuel cell reactants · CPC title

• H01M8/2455

  with liquid, solid or electrolyte-charged reactants · CPC title

• H01M8/04201

  Reactant storage and supply, e.g. means for feeding, pipes · CPC title