Fuel cell system and control method for fuel cell system

Patent metadata

Field	Value
Publication number	US-10090544-B2
Application number	US-201113817794-A
Country	US
Kind code	B2
Filing date	Jul 27, 2011
Priority date	Aug 20, 2010
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

A fuel cell system includes: a fuel cell stack; a fuel gas supply/exhaust unit; an oxidant gas supply/exhaust unit; and a control unit. The control unit determines whether there is a phenomenon in the fuel cell stack resulting from local power generation concentration within a plane of a membrane electrode assembly due to a water distribution. When it is determined that there is the phenomenon, the control unit controls at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit.

First claim

What is claimed is:

1. A fuel cell system comprising:
a fuel cell having a membrane electrode assembly, the membrane electrode assembly having an anode and a cathode which are respectively bonded to both surfaces of an electrolyte membrane formed of a solid polymer;
a fuel gas flow passage flowing fuel gas along a surface of the anode;
an oxidant gas flow passage flowing oxidant gas along a surface of the cathode;
a fuel gas supply/exhaust unit configured to supply fuel gas to the anode and configured to exhaust anode off-gas exhausted from the anode, via the fuel gas flow passage;
an oxidant gas supply/exhaust unit configured to supply oxidant gas to the cathode and configured to exhaust cathode off-gas exhausted from the cathode, via the oxidant gas flow passage;
a frame member provided at an outer peripheral portion of the membrane electrode assembly;
a first temperature sensor provided at a first portion of the frame member, the first temperature sensor being configured to detect a temperature of the first portion;
a second temperature sensor provided at a second portion of the frame member, the second portion being higher in temperature than the first portion, and the second temperature sensor being configured to detect a temperature of the second portion;
a power generation concentration determining unit programmed to determine whether there is a phenomenon in the fuel cell resulting from local power generation concentration, where the amount of power generation per unit area locally exceeds an allowable value, within a plane of the membrane electrode assembly due to a water distribution, the water distribution including a water content distribution within a plane of the electrolyte membrane, a residual water distribution in the fuel gas flow passage and a residual water distribution in the oxidant gas flow passage, and the power generation concentration determining unit being programmed to determine whether a difference between the temperature of the second portion and the temperature of the first portion is larger than a predetermined threshold; and
a control unit being programmed to determine whether there is insufficient water content of the electrolyte membrane and to increase a control value that is a back pressure of cathode off gas when:
(i) it is determined that the difference between the temperature of the second portion and the temperature of the first portion is larger than the predetermined threshold; and
(ii) it is determined that there is insufficient water content of the electrolyte membrane.

2. The fuel cell system according to claim 1 , wherein the first portion is a portion located adjacent to a portion from which the oxidant gas is introduced into the cathode, and the second portion is a portion located adjacent to a portion from which the cathode off-gas is exhausted from the cathode.

3. The fuel cell system according to claim 1 , wherein the first temperature sensor and the second temperature sensor are provided on the same frame member.

4. The fuel cell system according to claim 1 , wherein as the difference between the predetermined threshold and the difference between the temperature of the second portion and the temperature of the first portion increases with respect to the threshold, the control unit is configured to increase the back pressure of cathode off gas.

5. The fuel cell system according to claim 1 , wherein (i) the fuel cell system includes a cathode off gas passage and a pressure regulating valve provided on the cathode off gas passage, and (ii) the control unit is programmed to decrease an opening degree of the pressure regulating valve to increase the back pressure of cathode off gas.

6. The fuel cell system according to claim 1 , wherein the temperature comparison to the predetermined threshold occurs subsequent to the determination that there is insufficient water content of the electrolyte membrane.

7. A control method for a fuel cell system that includes: a fuel cell that has a membrane electrode assembly in which an anode and a cathode are respectively bonded to both surfaces of an electrolyte membrane formed of a solid polymer, a fuel gas flow passage flowing fuel gas along a surface of the anode, and an oxidant gas flow passage flowing oxidant gas along a surface of the cathode; a fuel gas supply/exhaust unit configured to supply fuel gas to the anode and configured to exhaust anode off-gas exhausted from the anode, via the fuel gas flow passage; and an oxidant gas supply/exhaust unit configured to supply oxidant gas to the cathode and configured to exhaust cathode off-gas exhausted from the cathode, via the oxidant gas flow passage; a frame member provided at an outer peripheral portion of the membrane electrode assembly; a first temperature sensor provided at a first portion of the frame member and configured to detect a temperature of the first portion; and a second temperature sensor provided at a second portion of the frame member, the second portion being higher in temperature than the first portion, and the second temperature sensor configured to detect a temperature of the second portion,
the control method comprising:
determining whether there is phenomenon in the fuel cell resulting from local power generation concentration, where the amount of power generation per unit area locally exceeds an allowable value, within a plane of the membrane electrode assembly due to a water distribution, the water distribution including a water content distribution within a plane of the electrolyte membrane, a residual water distribution in the fuel gas flow passage and residual water distribution in the oxidant gas flow passage;
determining whether there is insufficient water content of the electrolyte membrane; and
when it is determined that there is the phenomenon, controlling at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit so as to eliminate the phenomenon;
determining whether a difference between the temperature of the second portion and the temperature of the first portion is larger than a predetermined threshold, and
when the difference between the temperature of the second portion and the temperature of the first portion is larger than the predetermined threshold and it is determined that there is insufficient water content of the electrolyte membrane, controlling at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit so that the difference between the temperature of the second portion and the temperature of the first portion becomes smaller than or equal to the predetermined threshold.

Assignees

• Matsusue Masaaki
• Toyota Motor Co Ltd

Inventors

• Matsusue Masaaki

Classifications

• H01M8/04828

  Humidity; Water content · CPC title

• H01M8/04291 Primary

  Arrangements for managing water in solid electrolyte fuel cell systems (H01M8/04119 takes precedence) · CPC title

• H01M8/045

  of anode reactants at the inlet or inside the fuel cell · CPC title

• H01M8/04529

  of the electrolyte · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title