Fuel cell stack health monitoring using groups of fuel cells

Patent metadata

Field	Value
Publication number	US-2017324106-A1
Application number	US-201615144936-A
Country	US
Kind code	A1
Filing date	May 3, 2016
Priority date	May 3, 2016
Publication date	Nov 9, 2017
Grant date	—

Abstract

A fuel cell stack includes a plurality of cell groups and a controller wherein each cell group comprises a plurality of fuel cells and a group sensor which measures one or more electrical characteristics of the respective cell group. The controller comprises one or more processors and memory and is communicatively coupled to each group sensor. The one or more processors execute machine readable instructions to compare a measured electrical characteristic of each cell group to one or more thresholds stored in memory, and indicate the need for diagnostics of the fuel cell stack when the comparison indicates a non-systemic event.

First claim

1 . A fuel cell stack comprising a plurality of cell groups and a controller wherein:
each cell group comprises a plurality of fuel cells and a group sensor; the group sensor measures one or more electrical characteristics of the respective cell group; the controller comprises one or more processors and memory; the controller is communicatively coupled to each group sensor; and the one or more processors execute machine readable instructions to
compare a measured electrical characteristic of each cell group to one or more thresholds stored in memory, and
indicate a need for diagnostics of the fuel cell stack when the comparison indicates a non-systemic event.

2 . The fuel cell stack as claimed in claim 1 wherein the electrical characteristic is an impedance of the cell group and the one or more processors execute machine readable instructions to compare a measured impedance of each cell group to an impedance threshold in memory and indicate a non-systemic event when the measured impedance of one or more cell groups is about equal to or greater than the impedance threshold.

3 . The fuel cell stack as claimed in claim 2 wherein the one or more processors execute machine readable instructions to modify the impedance threshold as the cell group ages.

4 . The fuel cell stack as claimed in claim 1 wherein the electrical characteristic is an impedance of the cell group and the one or more processors execute machine readable instructions to measure a rate of change of the impedance of the respective cell group and indicates a non-systemic event in the cell group if the rate of change of the impedance of the cell group is about equal to or greater than a rate of impedance change threshold.

5 . The fuel cell stack as claimed in claim 1 wherein the one or more processors execute machine readable instructions to
compare the electrical characteristic measurements of each cell group; and
identify any cell groups with electrical characteristics which are greater than a separation factor from the electrical characteristics of the rest of the cell groups in the fuel cell stack.

6 . The fuel cell stack as claimed in claim 1 wherein the electrical characteristic comprises a group frequency and the one or more processors execute machine readable instructions to measure an impedance of each cell group at the group frequency.

7 . The fuel cell stack as claimed in claim 6 wherein the group frequency is between about 100 Hz and about 10 kHz.

8 . The fuel cell stack as claimed in claim 6 wherein the group frequency is adjusted to increase a magnitude of the measured impedance of each cell group such that a lower frequency results in a larger magnitude measured impedance and a higher frequency results in a lesser magnitude measured impedance.

9 . The fuel cell stack as claimed in claim 1 wherein the electrical characteristic is a voltage of the cell group and the one or more processors execute machine readable instructions to compare a measured voltage of a respective cell group to an voltage threshold and indicate a non-systemic event when the measured voltage of one or more cell groups is about equal to or lesser than the voltage threshold.

10 . The fuel cell stack as claimed in claim 9 wherein the one or more processors execute machine readable instructions to modify the voltage threshold as the cell group ages.

11 . The fuel cell stack as claimed in claim 1 wherein the electrical characteristic is a voltage of the cell group and the one or more processors execute machine readable instructions to
measure a rate of change of the voltage of the respective cell group, and
indicate a non-systemic event in the cell group if the rate of change of the voltage of the cell group is about equal to or greater than a rate of voltage change threshold.

12 . The fuel cell stack as claimed in claim 1 wherein a first threshold and a second threshold are stored in memory and the one or more processors execute machine readable instructions to
compare the measured electrical characteristics to the first threshold and the second threshold;
execute a first remedial action if the comparison of the measured electrical characteristic with the first threshold indicates a non-systemic event; and
execute a second remedial action if both comparisons of the measured electrical characteristic with the first threshold and the second threshold indicate a non-systemic event.

13 . The fuel cell stack as claimed in claim 12 wherein the first remedial action is to increase a flow of a reactant through the fuel cell stack and the second remedial action is to shutdown the fuel cell stack.

14 . The fuel cell stack as claimed in claim 12 wherein the first remedial action is to decrease an electrical load on the fuel cell stack and the second remedial action is to shutdown the fuel cell stack.

15 . The fuel cell stack as claimed in claim 12 wherein the one or more processors execute machine readable code to
compare the measured electrical characteristic to the first threshold after the first remedial action is executed;
resume normal operation of the fuel cell stack if the comparison of the measured electrical characteristic with the first threshold no longer indicates a non-system fault;
compare the measured electrical characteristic to the second threshold after the second remedial action is executed; and
resume normal operation of the fuel cell stack if the both comparisons of the measured electrical characteristic with the first threshold and the second threshold no longer indicates a non-system fault.

16 . The fuel cell stack as claimed in claim 1 wherein individual fuel cell monitoring is not required.

17 . A fuel cell propulsion system comprising a controller, a fuel cell stack, one or more valves, and one or more fuel storage vessels wherein:
the one or more valves fluidly couple the one or more fuel storage vessels to the fuel cell stack; each fuel storage vessel stores either a reactant or air; the fuel cell stack comprises a plurality of cell groups; each cell group comprises a plurality of fuel cells and a group sensor; the group sensor measures one or more electrical characteristics of the respective cell group; the controller comprises one or more processors and memory; the controller is communicatively coupled to each group sensor; and the one or more processors execute machine readable instructions to
compare a measured electrical characteristic to one or more thresholds stored in memory, and
actuate the one or more valves to adjust a flow of reactant or air from the fuel storage vessels to the fuel cell stack when the comparison indicates a non-systemic event.

18 . The fuel cell propulsion system as claimed in claim 17 wherein the electrical characteristic is an impedance of the cell group and the one or more processors execute machine readable instructions to compare a measured impedance of each cell group to an impedance threshold in memory and indicate a non-systemic event when the measured impedance of one or more cell groups is about equal to or greater than the impedance threshold.

19 . The fuel cell propulsion system as claimed in claim 17 wherein the one or more processors execute machine readable instructions to
compare measured electrical characteristics of each cell group; and
identify any cell groups with electrical characteristics which are greater than a separation factor from the electrical characteristics of the rest of the cell groups in the fuel cell stack.

20 . The

Assignees

• Gm Global Tech Operations Llc
• Honda Motor Co Ltd

Inventors

• Sinha Manish
• Rapaport Pinkhas A
• Yoshida Hiromichi
• Toyota Shohei
• Lai Yeh-Hung

Classifications

• H01M8/04559

  of fuel cell stacks · CPC title

• H01M8/04992 Primary

  characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M8/04649

  of fuel cell stacks · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title