A fuel cell system that includes a fuel cell body that is formed by a membrane electrode assembly including an anode catalyst and a cathode catalyst between which an electrolyte membrane is sandwiched and a pair of separators forming an anode-catalyst-side flow channel and a cathode-catalyst-side flow channel, a fuel supply system configured to supply fuel gas to the fuel cell body, an oxidant supply system configured to supply oxidant gas to the fuel cell body, a control device that controls these supply systems in accordance with an operating state of the fuel cell system and a catalyst deterioration recovery device that recovers deterioration of the anode catalyst. The catalyst deterioration recovery device includes a plurality of catalyst deterioration recovery means, a specific operating state detecting means configured to detect a specific operating state of the fuel cell system and a selecting means configured to selectively activate the plurality of catalyst deterioration recovery means in accordance with the specific operating state.

A control method for fuel cell system capable of executing an idle stop operation is provided, in which operation power generation of a fuel cell is selectively stopped according to a required output of a load and cathode gas is intermittently supplied to the fuel cell during an operation stop. An upper limit value and a lower limit value of an output voltage of the fuel cell during the idle stop operation is set, the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and the lower limit value, a wet/dry state of the fuel cell is detected, a wet/dry appropriate range in which the wet/dry state of the fuel cell during the idle stop operation is appropriate is set, and it is determined whether or not the detected wet/dry state of the fuel cell is within the set wet/dry appropriate range. If the wet/dry state of the fuel cell is determined to be outside the set wet/dry appropriate range, the output voltage of the fuel cell is reset, and the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and lower limit value of the reset output voltage.

A technique of diagnosing a fuel cell stack is provided. In particular, current and voltage of a fuel cell stack are measured during driving of a fuel cell vehicle and the current and voltage are sequentially stored. It is then determined based on the stored current whether the vehicle is being operated at constant current. Different factors are analyzed depending on whether the vehicle is being operated at constant current, and then it is determined whether the fuel cell stack is in a normal state. A moisture supply into the fuel cell stack is calculated if it is determined that the fuel cell stack is not in the normal state. Based on the calculated moisture supply, whether the fuel cell stack is in a dryout state is diagnosed.

A fuel cell system, comprising: a measurer that measures an impedance of the fuel cell; a controller that controls an operation state of the fuel cell; and an acquirer that acquires a dryness degree of the fuel cell from the measured impedance when the operation state is a first operation state, and acquires the dryness degree of the fuel cell as a wet state when the operation state is a second operation state in which a water balance is more than the first operation state.

Methods and systems are provided for cold-start of fuel cell stack in fuel cell vehicles. In one example, a method may include in response to cold-start of fuel cell vehicle, limiting the load drawn from the fuel cell stack. In addition, a coolant pump may be operated at a higher rate through a bypass loop to get heat quickly to the fuel cell stack to increase the solubility of water in the fuel cell stack to prevent ice formation. The net effect is that the fuel cell stack is then operated within the ice capacity of the membrane, and start-up at lower temperatures is possible without experiencing an intermittent performance drop due to active area freezing. Once the fuel cell stack is sufficiently warmed up, the coolant pump rate and fuel cell stack may be adjusted according to the demand.

A method for controlling a fuel cell vehicle includes acquiring a state data, deriving a mathematical voltage model by substituting the acquired state data into a voltage calculation formula, measuring a voltage of a fuel cell, approximating a mathematical voltage model to a measurement voltage and deriving the reaction area data when the mathematical voltage model approximates the measurement voltage, and controlling the system of the fuel cell vehicle based on the derived reaction area data to eliminate or prevent an over-humidification situation of the fuel cell.

A control device for a fuel cell system comprises a hydrogen deficiency judging part configured to judge if a hydrogen deficiency which is a state in which an amount of hydrogen supplied to the fuel cell is insufficient compared with an amount of hydrogen required for power generation has occurred, a hydrogen deficiency elimination judging part configured to judge if the hydrogen deficiency has been eliminated after the hydrogen deficiency judging part judges that the hydrogen deficiency has occurred and a breakage control part configured to make the circuit breaker temporarily break an electrical connection of the fuel cell and the electrical load part when the hydrogen deficiency elimination judging part judges that the hydrogen deficiency has been eliminated.

A fuel cell system includes: a processing unit configured to perform an activation process of temporarily reducing a cathode potential of a single fuel cell to a target potential for a duration time at a processing frequency; a cationic impurity amount estimating unit configured to estimate an amount of cationic impurities included in an electrolyte membrane of the single fuel cell; and a process degree determining unit configured to determine, when the amount of cationic impurities is large, a degree of the activation process which is higher than that determined when the amount of cationic impurities is small by performing at least one action among actions of changing conditions of the activation process, the actions including an action of reducing the target potential, an action of increasing the duration time, and an action of increasing the processing frequency. The processing unit performs the activation process to the determined degree.

A fuel cell system and method that enables warm-up power generation corresponding to the residual water volume in the fuel cell stack without using auxiliary devices for measuring the residual water volume in the fuel cell stack. A controller computes total generated electrical energy Q by integrating of the generated current detected by current sensor during the period from start-up to shutting down of the fuel cell system, and stores the result in total generated electrical energy storage part. Also, controller measures fuel cell temperature Ts at the last shutting down cycle with temperature sensor, and stores it in power generation shutting down temperature storage part. When the fuel cell system is started, controller estimates residual water volume WR that remains in fuel cell stack 2 on the basis of fuel cell temperature Ts when power generation is shut down, total generated electrical energy Q, and fuel cell start-up temperature Tn, and sets the generated electrical power for warm-up at start-up on the basis of said residual water volume Wr.

A fuel cell internal state detection system includes estimation object state quantity setting unit for setting a suitable estimation object state quantity as an index of an internal state, an impedance value acquisition unit configured to obtain an impedance value of a fuel cell, an impedance usability judging unit configured to judge whether or not the obtained impedance value is usable for the calculation of the estimation object state quantity, estimation object state quantity calculation unit for calculating the estimation object state quantity set by the estimation object state quantity setting unit on the basis of the obtained impedance value when the impedance value is judged to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit, and an unusable-scene process execution unit configured to perform an unusable-scene process when the impedance value is judged not to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit.