Fuel cell system and control method for fuel cell system

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 configured 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 configured 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 configured to control at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit so as to eliminate the phenomenon when the power generation concentration determining unit determines that there is the phenomenon, the control unit being configured to control 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, when the difference between the temperature of the second portion and the temperature of the first portion is larger than the predetermined threshold.

The 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;
• 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 power generation concentration determining unit configured 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, the power generation concentration determining unit being configured to estimate the water distribution on the basis of an operating condition of the fuel cell, and the power generation concentration determining unit being configured to determine on the basis of the estimated water distribution whether a cause of the power generation concentration is a locally insufficient water content in the electrolyte membrane, a locally excessive amount of residual water in the fuel gas flow passage or a locally excessive amount of residual water in the oxidant gas flow passage;
• and
• a control unit configured to control at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit so as to eliminate the phenomenon when the power generation concentration determining unit determines that there is the phenomenon, the control unit being configured to control at least one of the fuel gas supply/exhaust unit and the oxidant gas supply unit on the basis of the determined cause of the power generation concentration, and the control unit being configured to control the fuel gas supply/exhaust unit so as to increase a flow rate of the fuel gas supplied to the anode when it is determined that the cause of the power generation concentration is a locally insufficient water content in the electrolyte membrane.

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;
• 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, 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.