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.

An online impedance spectrum measuring device and method for a vehicle-mounted hydrogen fuel cell includes: a controllable alternating current source, configured to apply a sinusoidal alternating signal; a cell voltage signal preceding-stage measuring circuit, configured to select to communicate with one monocell via a voltage signal gating circuit; a current sensor and a cell current signal preceding-stage measuring circuit connected with the current sensor; and a signal conditioning and amplifying circuit, a multi-channel simultaneous sampling analog-digital conversion circuit, a digital signal processor and an upper computer, which are connected in sequence, wherein the signal conditioning and amplifying circuit is connected to the cell voltage signal preceding-stage measuring circuit and the cell current signal preceding-stage measuring circuit, separately; and the upper computer is connected with the controllable alternating source and the voltage signal gating circuit.

When a time point of occurrence of a stop state of a fuel cell system is predicted during traveling, a drying state control that causes a fuel cell stack to transition to a dry state is started a predetermined time (a required drying time) before the predicted time point of occurrence of the stop state.

A system for capturing carbon dioxide in flue gas includes a fuel cell assembly including at least one fuel cell including a cathode portion configured to receive, as cathode inlet gas, the flue gas generated by the flue gas generating device or a derivative thereof, and to output cathode exhaust gas and an anode portion configure to receive an anode inlet gas and to output anode exhaust gas, a fuel cell assembly voltage monitor configured to measure a voltage across the fuel cell assembly, and a controller configured to receive the measured voltage across the fuel cell assembly from the fuel cell assembly voltage monitor, determine an estimated carbon dioxide utilization of the fuel cell assembly based on the measured voltage across the fuel cell assembly, and reduce the carbon dioxide utilization of the fuel cell assembly when the determined estimated carbon dioxide utilization is above a predetermined threshold utilization.

A control method and system of a fuel cell electric vehicle stack. The control method comprises obtaining insulation resistance of the stack, comprising at least two sub-stacks connected in parallel; and disconnecting a sub-stack with insulation failure from a DC bus and then causing the stack to enter a failure mode when it is determined that the insulation resistance of the stack is smaller than a first preset threshold. The stack is determined to have an insulation failure when it is determined that the insulation resistance of the stack is smaller than the first preset threshold. The sub-stack with the insulation failure is located and disconnected the sub-stack with insulation failure from a DC bus, and the stack is then caused to run in a failure mode to perform failure protection, avoid deterioration of the insulation failure and burnout of the stack and improve the safety performance of the stack.

To provide a fuel cell system configured to appropriately measure the AC impedance of a fuel cell. A fuel cell system wherein a controller controls ON and OFF of switches of n phases; wherein the controller monitors current values of coils; the controller operates the switches of the n phases at different phases; wherein the controller operates duty ratios of the switches of the n phases with periodically increasing and decreasing them, and the controller measures an AC impedance of a fuel cell from a current waveform of and a voltage waveform of the fuel cell; and wherein, when the controller determines that a predetermined condition 1 is met, the controller makes amplitudes which increase and decrease the duty ratios large compared to other operating conditions.

A fuel cell system includes a fuel cell stack of a plurality of power generation cells and an impedance measuring device for measuring the impedance in the fuel cell stack. When stopping the operation of the fuel cell system, a method for stopping the operation of the fuel cell system operates the plurality of power generation cells to generate electric power, until the impedance value becomes equal to or greater than an objective impedance value. After the impedance value has become equal to or greater than the objective impedance value, the operation stopping method still continues the power generation of the multiple power generation cells for a given period of time.

The present invention relates to an SOEC system (1), comprising a fuel cell stack (2) having a gas side (3) and an air side (4), and an ejector (5) for supplying a process fluid to a gas inlet (6) on the gas side (3), wherein the ejector (5) comprises a primary inlet (7), for introducing a water-containing primary process fluid through a primary line (8) of the SOEC system (1) into a primary portion (9) of the ejector (5), and a secondary inlet (10), for introducing recirculated secondary process fluid through a recirculation line (11) of the SOEC system (1) from a gas outlet (12) on the gas side (3) into a secondary portion (13) of the ejector (5), wherein the SOEC system (1) further comprises a control gas supply portion (14) for supplying control gas into the primary portion (9) and into the secondary portion (13) in order to control a pressure and/or mass flow in the primary portion (9) and in the secondary portion (13), and wherein the control gas supply portion (14) comprises a valve arrangement (19, 20) for controlling the pressure and/or the mass flow in the primary portion (9) and in the secondary portion (13).

The invention further relates to a method for operating an SOEC system (1) according to the invention.

A stack module fault detection system, comprising an insulation resistance tester; a stack module, consisting of a plurality of stacks; and a plurality of switch groups, wherein each switch group comprises a first switch and a second switch, each switch group is respectively connected with a stack, the first end of the first switch is connected with the positive electrode of the stack, and the first end of the second switch is connected with the negative electrode of the stack; the second end of the first switch is connected with the positive electrode of the insulation resistance tester, and the second end of the second switch is connected with the negative electrode of the insulation resistance tester. A controller connected with the control end of the switch group controls the opening and closing of the switch group. The insulation resistance tester detects the insulation resistance of each stack in turn and sends the insulation resistance to the controller to monitor the insulation fault in the stack module. Under the condition of not disassembling the stack module, the insulation resistance of each stack is detected, and the stack with insulation fault can be located, so that the operation of fault positioning is simplified.

A method for controlling a carbon dioxide utilization in a fuel cell assembly includes: measuring a voltage across the fuel cell assembly; determining an estimated carbon dioxide utilization of the fuel cell assembly based on at least the measured voltage across the fuel cell assembly by determining an expected voltage of the fuel cell assembly based on at least a temperature of the fuel cell assembly, a current density across the fuel cell assembly, a fuel utilization of the fuel cell assembly, and a cathode oxygen utilization of the fuel cell assembly; determining the estimated carbon dioxide utilization based on a comparison between the measured voltage and the determined expected voltage; comparing the determined estimated carbon dioxide utilization to a predetermined threshold utilization; and upon determining that the determined estimated carbon dioxide utilization is higher than the predetermined threshold utilization, reducing the carbon utilization of the fuel cell assembly.