A fuel cell system calculates a target value of a flow rate of cathode gas to be supplied to a fuel cell stack according to a request of the fuel cell stack, controls a flow rate of the cathode gas to be supplied by the compressor according to an operating state of the fuel cell system, controls a bypass valve based on a target fuel cell supply flow rate so that the flow rate of the cathode gas to be supplied from the compressor to the fuel cell stack reaches the target fuel cell supply flow rate, and limits the flow rate of the cathode gas to be supplied by the compressor when the bypass valve has a predetermined opening and the flow rate of the cathode gas to be supplied to the fuel cell stack is not smaller than the target fuel cell supply flow rate.

A fuel cell system includes a component in a circulation passage for off-gas, a battery temperature acquisition unit configured to acquire a fuel cell temperature, a component temperature acquisition unit configured to acquire a component temperature, a state-of-charge acquisition unit configured to acquire a state of charge of a secondary battery, and a controller configured to, when a temperature difference between the acquired fuel cell temperature and the acquired component temperature is greater than or equal to a predetermined temperature difference at the time of a stop of power generation of the fuel cell system, perform a warm-up operation of a fuel cell and store electric power generated through the warm-up operation in the secondary battery while the state of charge of the secondary battery is lower than a predetermined state of charge, and, after completion of the warm-up operation, perform the scavenging operation at predetermined scavenging power.

A fuel cell system includes: a fuel cell stack at which generation of electricity is carried out by chemical reaction of hydrogen and oxygen, and from which water and exhaust are discharged; and a liquid water amount estimation section that estimates an amount of liquid water among the discharged water, based on an amount of current that is generated by the fuel cell stack, an amount of air that is supplied to the fuel cell stack, a temperature of the air, a relative humidity of the air, a temperature of exhaust that is discharged from the fuel cell stack, and a pressure of the exhaust.

A method of controlling the operation of a fuel cell system is provided. The method includes diagnosing a water shortage state in a fuel cell stack based on degradation of cooling performance and deterioration of the fuel cell stack and determining a diagnosis level of the fuel cell system based on the diagnosed water shortage state of the fuel cell stack. In addition, a regenerative operation is performed by selecting a regenerative operation mode which corresponds to the determined diagnosis level.

The present invention relates to a fuel cell system capable of adjusting a bypass flow rate, in which the bypass flow rate can be automatically adjusted according to the temperature of an exhaust gas discharged from a fuel cell stack. The fuel cell system capable of adjusting a bypass flow rate, according to an embodiment of the present invention, comprises: an exhaust gas inlet flow path; an exhaust gas discharge flow path; a bypass flow path for bypassing a membrane humidifier to allow at least a portion of an exhaust gas discharged from a fuel cell stack to flow to the exhaust gas discharge flow path; and a bypass flow rate control unit that is formed in the bypass flow path and adjusts the opening degree of the bypass flow path according to the temperature of the exhaust gas discharged from the fuel cell stack.

A fuel cell vehicle on which a fuel cell system including a fuel cell is mounted includes a discharge mechanism configured to discharge moisture, generated by the fuel cell, from the fuel cell system to an outside of the vehicle, a camera configured to capture an image outside the vehicle, and an electronic control unit configured to determine whether predetermined control based on an information obtained from the image and executed or stopped in response to a driving status or drive mode of the vehicle in an on-state of an ignition switch is being executed, and, when it is determined that the predetermined control is being executed, execute a low discharge process in which a discharge flow rate of water vapor that is discharged from the discharge mechanism to the outside of the vehicle is reduced as compared to when it is determined that the predetermined control is stopped.

A fuel cell cooling system includes an air temperature estimating unit, an air temperature sensor and an abnormality determining unit. The air temperature sensor senses an air detection temperature of the air that flows out of the air cooler and is supplied to the fuel cell. The air temperature estimating unit estimates an air estimation temperature of the air, based on a temperature of a refrigerant flowing into the air cooler, a power supply quantity of a power supplied to the circulation pump, a temperature of the air flowing into the air cooler and a flow volume of the air. The abnormality determining unit determines that a circulation flow volume of the refrigerant is in an abnormal state when the air detection temperature is higher than the air estimation temperature by a value greater than or equal to a predetermined value.

A high temperature electrochemical cell includes a solid electrolyte separating a cathode and an anode, an anode flow field adjacent the anode, a cathode flow field, having an exhaust gas stream pathway, downstream from the cathode, and a thermal management system including a controller programmed to, in response to the exhaust gas stream temperature input, activate at least one component, configured to reduce temperature of the exhaust gas stream to a temperature within a threshold range corresponding to a temperature range promoting condensation of Cr-containing gas into solid, liquid, or aqueous Cr.sub.2O.sub.3 and H.sub.2CrO.sub.4, the high temperature electrochemical cell having an operating temperature of about 600-1000? C.

A fuel cell system mounted in a mobile object is equipped with a bypass flow passage that establishes communication between an air compressor and an exhaust gas flow passage, and a valve that adjusts an amount of air supplied to the bypass flow passage. A control unit performs a process for increasing a flow rate of air caused to flow through the bypass flow passage, by controlling a drive amount of the air compressor and the opening degree of the valve, when an outside air temperature is equal to or lower than a threshold and a speed of the mobile object is equal to or lower than a determination speed. In the process, a flow rate of air at a first temperature that is lower than a second temperature that is equal to or lower than the threshold is larger than a flow rate of air at the second temperature.

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.