A current limiting method of a fuel cell stack is capable of preventing current of the fuel cell stack from rapidly dropping to prevent jerking or shock from occurring while a vehicle travels. The method includes: determining whether performance deterioration of a unit cell of the fuel cell stack has occurred, employing a feed forward control type current limiting logic of the fuel cell stack before an output of the fuel cell vehicle is lowered, decreasing the current of the fuel cell stack to a predetermined level by the feed forward control type current limiting logic, and gradually restoring the current of the fuel cell stack to a maximum current usage value from a point in time when the current of a load is used.

A method for operating a fuel cell power generation system is presented and includes sequentially resting fuel cell modules corresponding to a designated reference module number, from among all fuel cell modules of the fuel cell power generation system, during a designated number of cycles while operating remaining fuel cell modules, gradually reducing a number of the fuel cell modules sequentially rested during the cycles from the reference module number, whenever average performance of the fuel cell modules is sequentially reduced by exceeding designated reference levels configured to be sequentially set, and repairing or replacing the fuel cell modules when the average performance of the fuel cell modules is reduced by a designated lower limit or more.

A method for diagnosing at least one fuel cell stack of a fuel cell device by way of a fuel cell diagnostic system includes: impressing a sinusoidal first and at least one sinusoidal second AC current into the fuel cell stack; recording a sinusoidal first and second voltage response of the fuel cell stack; evaluating the first voltage response and evaluating the second voltage response by way of an analytical algorithm for a differential impedance analysis; determining a first resistance, a second resistance and a capacitance of the fuel cell stack by specifying an equivalent circuit diagram for the fuel cell stack; and diagnosing the fuel cell stack on the basis of the determined first resistance, the determined second resistance and the determined capacitance, wherein the diagnosis is carried out in real time. A computer-readable storage medium and a fuel cell diagnostic system are also described.

A fuel cell system comprises a controller configured to determine whether a condition relating to a stop pattern of the fuel cell system satisfies a predetermined condition, and an output unit configured to output a warning when it is determined that the condition relating to the stop pattern satisfies the predetermined condition.

A method for operating a fuel cell system having a fuel cell stack includes detecting a failure of a first cooling fan that blows exterior air to a first radiator, opening a first valve such that first cooling water that passes via the fuel cell stack flows toward the fuel cell stack, controlling an RPM of a blower of an air conditioning system to a maximum level, controlling an opening degree of a second valve according to a cooling degree of the first radiator and a cooling degree of the air conditioning system, and controlling an RPM of a first pump that pumps the first cooling water to a maximum level.

A method for distinguishing the cause of voltage losses in a fuel cell device includes: a) Detection of a quasi-stationary operation of the fuel cell device, b) Acquisition and storage of a measured current-voltage characteristic curve with the current values and the voltage values of a fuel cells stack of the fuel cell device, c) Use of a PtOx model to determine PtOx voltage losses and calculation of a corrected current-voltage characteristic curve for the PtOx-free and normally humidified fuel cell stack, and d) Comparison of the current-voltage characteristic curves determined in step b) and in step c) and detection of an at least partially dried-out fuel cell stack if the measured current-voltage characteristic curve runs below the corrected current-voltage characteristic curve. A fuel cell device and a motor vehicle comprising a fuel cell device are also provided.

A system for determining performance of a fuel cell stack may include a vehicle that collects a current of the fuel cell stack and a current of the fuel cell stack and a server that receives the voltage of the fuel cell stack and the current of the fuel cell stack from the vehicle in real time, determines an average state of health (SOH) of the fuel cell stack for each current section within an effective current range based on the current of the fuel cell stack and the voltage of the fuel cell stack within the effective current range, determines an overall average SOH in the effective current range based on the average SOH of the fuel cell stack for each current section, and determines whether the fuel cell stack has failed based on the overall average SOH.

A safety management system for an aircraft, or a propulsion system thereof including a fuel cell assembly and a combustion engine, may include various sensors and controllers configured to execute a safety action. At least one sensor is configured to detect at least one operating parameter of the propulsion system, and a controller is configured to determine that the at least one operating parameter has achieved a safety threshold and to execute a safety action when the at least one operating parameter has achieved the safety threshold. The safety action is configured to control operation of the fuel cell assembly and to control operation of the combustion engine.

A method and apparatus for detecting oxidation in at least one planar fuel cell stack that includes a multitude of cells is described. The height of the stack is measured to determine if there has been an increase from a previously-measured height. Such an increase correlates with the oxidation of at least some of the planar cells. In some cases, the fuel flow rate or airflow rate to each fuel cell stack can be adjusted, based in part on the oxidation detection technique. A power delivery system with at least two fuel cell stacks is also described, and it includes a stack height-measurement system, a health monitor for the fuel cell stacks, and a load balancer or airflow regulator.

The fuel cell system includes: a fuel cell; an anode supply pipe; a fuel gas supplier disposed at the anode supply pipe, the fuel gas supplier configured to adjust a supply quantity of a fuel gas to be supplied to the fuel cell; an ejector disposed at the anode supply pipe at a position between the fuel gas supplier and the anode supply port; an anode circulation pipe connected to the anode discharge port and the ejector; a circulation stop unit disposed at the anode circulation pipe, the circulation stop unit configured to stop circulation of the fuel gas through the anode circulation pipe; a pressure sensor configured to detect a pressure in the anode supply pipe at a position between the ejector and the anode supply port; and a controller. When a first pressure acquired from the pressure sensor is equal to or less than a predetermined lower limit value, the controller controls the fuel gas supplier to perform constant quantity supply control to supply the fuel gas of a predetermined supply quantity, and controls the circulation stop unit to perform circulation stop control to stop the circulation through the anode circulation pipe, and the controller determines abnormality at the ejector and the anode circulation pipe by using a second pressure acquired from the pressure sensor after the fuel gas supplier performs the constant quantity supply control and the circulation stop unit performs the circulation stop control.