Cell voltage control through oxygen starvation for fuel cell systems

Patent metadata

Field	Value
Publication number	US-2023261223-A1
Application number	US-202217669867-A
Country	US
Kind code	A1
Filing date	Feb 11, 2022
Priority date	Feb 11, 2022
Publication date	Aug 17, 2023
Grant date	—

Abstract

Systems and methods of managing the voltage of fuel cells during no-load or low load events are disclosed. The systems may employ one or more valves such as an inlet and outlet valve for metering the fuel (e.g., hydrogen) and/or oxidant (e.g., oxygen) provided to the fuel cell. The voltage or voltage rise may be limited by starving the fuel cell of, for example, oxygen. A controller may be employed for controlling the one or more valves during a no-load or low load event such as start-up, idling, or stopping.

First claim

What is claimed is:

1 . A vehicle power system comprising:
a fuel cell including (i) an anode and a cathode with an electrolyte therebetween, (ii) a fuel passage configured to provide a fuel to the anode; and (iii) an oxidant passage configured to provide an oxidant to the cathode, the oxidant passage having an inlet and an outlet, the inlet comprising an inlet valve and the outlet comprising an outlet valve; a compressor in fluid communication with the inlet and configured to provide the fuel cell a supply of oxidant during operation, the inlet valve being configured to manage an amount of oxidant provided to the cathode such that during a no-load or low load event the amount of oxidant is below a threshold operating amount; and a bypass valve between the compressor and the inlet valve, the bypass valve configured to release the oxidant such that the compressor does not exceed a threshold pressure.

2 . The vehicle power system of claim 1 , wherein the inlet valve is configured to be positioned at a position between an opened and a closed position, the position corresponding to a predetermined voltage increase rate.

3 . The vehicle power system of claim 1 , further comprising an additional valve downstream of the outlet valve, the additional valve being configured to coordinate with the inlet and outlet valves to manage the amount of oxidant supplied to the cathode.

4 . The vehicle power system of claim 1 , wherein the inlet valve is configured to manage the amount of oxidant provided to the cathode during the no-load or low load event as long as the fuel cell was previously in a hydrogen-protective-state.

5 . The vehicle power system of claim 4 , wherein the inlet valve is configured to manage the amount of oxidant provided to the cathode by ramping-up an oxidant flow rate.

6 . The vehicle power system of claim 1 , wherein the inlet valve is configured to manage the amount of oxidant provided to the cathode by stepping-up an oxidant flow rate when the fuel cell was not previously in a hydrogen-protective-state.

7 . A vehicle comprising an electric machine configured to be powered by the vehicle power system of claim 1 .

8 . A vehicle power system comprising:
a fuel cell including an oxidant inlet valve and an oxidant outlet valve; an external circuit connected to the fuel cell and having electrical contacts that move to and from an opened position and a closed position such that in the closed position and during operation the fuel cell powers an electric machine connected to the external circuit; and a controller programmed to initiate a command to supply an oxidant to the fuel cell such that
responsive to a load being greater than a threshold amount, the controller positions the inlet and outlet valves to provide an amount of oxidant to the fuel cell that is 80-100% of a full-capacity amount; and
responsive to the load being less than the threshold amount, the controller positions the inlet and outlet valves to provide an amount of oxidant to the fuel cell that is less than 80% of the full-capacity amount.

9 . The vehicle power system of claim 8 , wherein the controller is programmed to meter the amount of oxidant via the valves such that a voltage of the fuel cell does not exceed a threshold voltage.

10 . The vehicle power system of claim 8 , wherein the controller is programmed to move the electrical contacts to the closed position prior to a current request and subsequent to metering the amount of oxidant such that a voltage increase of the fuel cell does not exceed a threshold voltage increase amount.

11 . The vehicle power system of claim 8 , wherein the controller is programmed to position the valves to meter the amount of oxidant and subsequently move the electrical contacts to the closed position such that a voltage increase of the fuel cell does not exceed a threshold voltage increase amount.

12 . The vehicle power system of claim 8 , wherein the command to supply an oxidant to the fuel cell is executed during a start-up, idling, or stop event.

13 . The vehicle power system of claim 8 , wherein the threshold amount is more than the idling load.

14 . A vehicle comprising the electric machine connected to the external circuit of the vehicle power system of claim 8 .

15 . A method of managing an electrochemical cell voltage comprising:
providing an oxidant to a fuel cell at a flow rate such that
responsive to a load being more than a threshold amount, the flow rate is an operating flow rate; and
responsive to the load being less than the threshold amount, the flow rate is less than the operating flow rate.

16 . The method of claim 15 , wherein the flow rate is controlled by one or more valves.

17 . The method of claim 16 , wherein the operating flow rate corresponds to the one or more valves being within 20 degrees of an opened position. the fuel cell.

18 . The method of claim 15 , wherein the flow rate is altered based on a voltage of the fuel cell.

19 . The method of claim 15 , wherein the flow rate is ramped up if the fuel cell was in a hydrogen-protective-state prior to introducing the oxidant.

20 . The method of claim 19 , wherein the flow rate is increased such that a voltage of the fuel cell does not exceed a threshold voltage.

Assignees

• Ford Global Tech Llc

Inventors

• Mejia Mejia Valentina
• Qiu Zeng
• Sanderson Jr William Frederick
• Milacic Milos
• Ben-Kalefa Majed

Classifications

• Y02T90/40

  Application of hydrogen technology to transportation, e.g. using fuel cells · CPC title

• B60L58/30 Primary

  for monitoring or controlling fuel cells · CPC title

• B60L50/72

  Constructional details of fuel cells specially adapted for electric vehicles · CPC title

• H01M8/04089 Primary

  of gaseous reactants · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title