Fuel cell system controller and associated method

• US 10,522,857 B2
• Filed: 09/28/2016
• Issued: 12/31/2019
• Est. Priority Date: 09/29/2015
• Status: Active Grant

• Current Assignee: Intelligent Energy Limited (Lb-shell Plc)
• Original Assignee: Intelligent Energy Limited (Lb-shell Plc)
• Inventors: Bowman, Jeremy
• Primary Examiner(s): Harris, Gary D
• Application Number:
  US15/761,376
• Publication Number:
  US 20180269503A1
• Time in Patent Office: 1,189 Days
• Field of Search: 429429
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04303 applied during shut-down
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04492 Humidity; Ambient humidity; Water content
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

The disclosure relates to a fuel cell stack and corresponding method of operating the fuel cell stack. The method comprises: determining a maximum allowable current that may be drawn from the fuel cell stack; repeatedly determining a magnitude of change to the prevailing maximum allowable current based on a prevailing allowable current ramp rate and an actual measured current of the fuel cell stack; updating the maximum allowable current according to the periodically determined magnitude of change; and controlling operating parameters of the fuel cell stack according to the prevailing maximum allowable current.

Claims

1. A method of operating a fuel cell system comprising:

repeatedly determining a maximum allowable current that may be drawn from the fuel cell system

based on a prevailing allowable current ramp rate, an actual measured current of the fuel cell system, and a parasitic current load of the fuel cell system; and

controlling a plurality of operating parameters of the fuel cell system according to a most recent determination of the maximum allowable current.

2. The method of claim 1 in which the step of controlling operating parameters of the fuel cell system comprises controlling an electrical load on the fuel cell system.

3. The method of claim 1 in which the most recent determination of the maximum allowable current comprises an increment or a decrement with respect to a less recent determination of the maximum allowable current.

4. The method of claim 1 in which the most recent determination of the maximum allowable current is determined according to the smaller of a magnitude of change corresponding to the prevailing allowable current ramp rate and a magnitude of change indicated by a current load requirement.

5. The method of claim 1 in which the most recent determination of the maximum allowable current is determined as a function of a period of time corresponding to a drying time of one or more fuel cells of the fuel cell system.

6. The method of claim 1 further including the step of periodically determining an allowable current ramp rate as a function of an actual measured current and a presently prevailing current ramp rate and at least one of:

a rated maximum current for the system;

a maximum ramp rate based on the capability of the fuel and/or oxidant delivery system;

a period of time corresponding to a drying time of one or more fuel cells of the fuel cell system; and

a period of time corresponding to a wetting time of the one or more fuel cells of the fuel cell system.

7. The method of claim 6 in which the rated maximum current comprises a predetermined maximum current for the physical configuration of the fuel cell system.

8. The method of claim 1 further including the step of inhibiting an increase in the maximum allowable current in the event of one or more of:

(i) a temperature of one or more cells exceeding a predetermined temperature threshold;

(ii) one or more cell voltages falling below a predetermined cell voltage threshold;

(iii) plural cell voltages exceeding a predetermined range.

9. The method of claim 1 further including determining the maximum allowable current as a function of one or more of:

(i) a total system running time;

(ii) a count of the total number of full stop-start cycles to which the fuel cell system has been subjected;

(iii) an ambient humidity falling below a predetermined low humidity threshold;

(iv) an ambient temperature falling below a predetermined low temperature threshold;

(v) an ambient temperature rising above a predetermined high temperature threshold;

(vi) a system voltage;

(vii) the proximity of one or more cell voltages to a minimum cell voltage threshold and/or the proximity of a system temperature to a maximum temperature limit; and

,

(viii) the maximum allowable current does not fall below a predetermined minimum current limit.

10. The method of claim 1 further including the step of overriding the maximum allowable current in the event of one or more of:

(i) the system entering a shutdown procedure;

(ii) one or more fuel cells of the system being isolated from a load.

11. A fuel cell system comprising:

one or more fuel cells disposed in series or in parallel; and

a controller conformed to perform the method of claim 1; and

,

in which the one or more fuel cells are air cooled fuel cells.

12. A vehicle comprising the fuel cell system of claim 11 for powering said vehicle.