To suppress the generation of condensed water and suppress the flow of the condensed water into a fuel cell stack. A fuel cell system comprising: a fuel cell stack, an elector set, a fuel gas supplier which supplies fuel gas to the ejector set, a circulation flow path, a mixed gas supply flow path, a temperature detector which detects a temperature of the fuel gas, and a controller, wherein the ejector set includes at least two ejectors in parallel, which are a first ejector that supplies first mixed gas to the fuel electrodes of the fuel cell stack, and a second ejector that supplies second mixed gas, in which a content ratio of the circulation gas is smaller than the first mixed gas, to the fuel electrodes of the fuel cell stack.

To suppress the generation of condensed water and suppress the flow of the condensed water into a fuel cell stack. A fuel cell system comprising: a fuel cell stack, an elector set, a fuel gas supplier which supplies fuel gas to the ejector set, a circulation flow path, a mixed gas supply flow path, a temperature detector which detects a temperature of the fuel gas, and a controller, wherein the ejector set includes at least two ejectors in parallel, which are a first ejector that supplies first mixed gas to the fuel electrodes of the fuel cell stack, and a second ejector that supplies second mixed gas, in which a content ratio of the circulation gas is smaller than the first mixed gas, to the fuel electrodes of the fuel cell stack.

The present disclosure generally relates to systems and methods for using a relative humidity sensor in a cathode exhaust stream of a fuel cell stack to optimize the performance and efficiency of the fuel cell stack.

A system for controlling purge operation of a fuel cell assembly includes a controller and one or more sensors configured to obtain respective sensor data. The fuel cell stack is configured to receive a stack coolant. The controller is configured to execute a first purge mode when at least one of a first enabling condition and a second enabling condition is met. The first purge mode defines a first group of setpoints, including a relatively low cathode stoichiometric ratio. The controller is configured to switch to a second purge mode when the coolant temperature is above a minimum warm-up temperature and a third mode when a relative humidity value of a stack cathode output falls below a threshold humidity. The second purge mode defines a second group of setpoints, including a relatively high cathode stoichiometric ratio.

A system for controlling purge operation of a fuel cell assembly includes a controller and one or more sensors configured to obtain respective sensor data. The fuel cell stack is configured to receive a stack coolant. The controller is configured to execute a first purge mode when at least one of a first enabling condition and a second enabling condition is met. The first purge mode defines a first group of setpoints, including a relatively low cathode stoichiometric ratio. The controller is configured to switch to a second purge mode when the coolant temperature is above a minimum warm-up temperature and a third mode when a relative humidity value of a stack cathode output falls below a threshold humidity. The second purge mode defines a second group of setpoints, including a relatively high cathode stoichiometric ratio.

A method for determining membrane humidification by determining the membrane protonic resistance of a fuel cell stack at humidified conditions, and normalizing the base resistance of the fuel cell stack against the base resistance of a reference fuel cell stack.

A fuel cell system includes a fuel cell, an air supplier, an air passage connected to the fuel cell, air supplied from the air supplier flowing in the air passage, a bleed passage branched off from the air passage on a side upstream of the fuel cell and joining the air passage on a side downstream of the fuel cell, part of the air supplied by the air supplier flowing in the bleed passage in such a manner as to circumvent the fuel cell, a bleed valve provided in the bleed passage, the bleed valve regulating the amount of air flowing in the bleed passage, an air supplier control unit which controls the air supplier to supply a predetermined amount of air, a wetness reduction determination unit which determines whether or not it is necessary to reduce a degree of wetness of the fuel cell, and a bleed amount control unit which reduces an opening of the bleed valve when the degree of wetness of the fuel cell needs to be reduced.

A fuel cell system includes a fuel cell, an air supplier, an air passage connected to the fuel cell, air supplied from the air supplier flowing in the air passage, a bleed passage branched off from the air passage on a side upstream of the fuel cell and joining the air passage on a side downstream of the fuel cell, part of the air supplied by the air supplier flowing in the bleed passage in such a manner as to circumvent the fuel cell, a bleed valve provided in the bleed passage, the bleed valve regulating the amount of air flowing in the bleed passage, an air supplier control unit which controls the air supplier to supply a predetermined amount of air, a wetness reduction determination unit which determines whether or not it is necessary to reduce a degree of wetness of the fuel cell, and a bleed amount control unit which reduces an opening of the bleed valve when the degree of wetness of the fuel cell needs to be reduced.

A fuel cell system includes: an external load connected to a fuel cell; an electric power adjusting unit configured to adjust a generated electric power of the fuel cell in accordance with electric power consumption of the external load; a humidity control unit configured to control humidity of an electrolyte membrane in the fuel cell on the basis of the generated electric power of the fuel cell; an output voltage detecting unit configured to detect an output voltage of the fuel cell; and a cross leakage determining unit configured to cause the humidity control unit to increase the humidity of the electrolyte membrane when the fuel cell generates the electric power, the cross leakage determining unit being configured to determine whether a cross leakage amount increases or not on the basis of a change in the output voltage at that time.

An electric power supply system includes first and second fuel cell stacks, a plurality of fuel tanks, a determination unit configured to determine the state of the first fuel cell stack during operation stop of the first and second fuel cell stacks, and a purging execution unit configured to execute purging by activating the first and second fuel cell stacks according to a determination result and opening on-off valves of the plurality of fuel tanks to supply fuel to the first and second fuel cell stacks.