On a start of a fuel cell system, (i) when the temperature of a high-voltage secondary battery obtained from a temperature sensor is higher than a predetermined reference value, a controller of the fuel cell system is configured to set an output voltage on a step-down side of a DC-DC converter to a higher voltage than a voltage of a low-voltage secondary battery and subsequently start an FC auxiliary machine using electric power from the high-voltage secondary battery. (ii) When the temperature of the high-voltage secondary battery obtained from the temperature sensor is equal to or lower than the predetermined reference value, on the other hand, the controller of the fuel cell system is configured to set the output voltage on the step-down side of the DC-DC converter to a lower voltage than the voltage of the low-voltage secondary battery and subsequently start the FC auxiliary machine using the electric power from the high-voltage secondary battery.

A method of cleaning power cells in an array of power cells, comprising coupling at least one first power cell to second power cells in an array of power cells and causing the second power cells to drive the at least one first power cell with a voltage to clean catalyst on the at least one first power cell.

A redox flow battery system including a cell and a monitor cell to which a same electrolyte solution is supplied; a current measuring unit that measures a current that is input to and output from the cell; a voltage measuring unit that measures an open circuit voltage of the monitor cell; and a computing unit. The computing unit includes a first processing unit, a second processing unit, and a third processing unit. The first processing unit computes an integral value obtained by integrating a current value measured by the current measuring unit, for an amount of time corresponding to a predetermined time constant. The second processing unit computes a corrected voltage value based on a measured voltage value measured by the voltage measuring unit and the integral value. And the third processing unit calculates a first state-of-charge value of the electrolyte solution from the corrected voltage value.

A fuel cell has an electrolyte membrane of 5 to 10 μm in thickness. A control device for this fuel cell comprises: a controller configured to control an amount of power generation by the fuel cell according to a required amount of electric power; and a power generation reducer configured to reduce the amount of power generation by the fuel cell at a humidity of an electrolyte membrane of 95 to 98% RH to be lower than the amount of power generation at the humidity of the electrolyte membrane of lower than 95% RH.

Systems and methods are provided for operating molten carbonate fuel cells to allow for periodic regeneration of the fuel cells while performing elevated CO.sub.2 capture. In some aspects, periodic regeneration can be achieved by shifting the location within the fuel cells where the highest density of alternative ion transport is occurring. Such a shift can result in a new location having a highest density of alternative ion transport, while the previous location can primarily transport carbonate ions. Additionally or alternately, periodic regeneration can be performed by modifying the input flows to the fuel cell and/or relaxing the operating conditions of the fuel cell to reduce or minimize the amount of alternative ion transport.

A hydrogen supply control system for a fuel cell is provided. The system includes a fuel cell stack that generates electricity using supplied hydrogen and air and a recirculation line that supplies hydrogen discharged from an outlet of the fuel cell stack back to an inlet of the fuel cell stack. A purge valve is disposed at an outlet side of the fuel cell stack of the recirculation line and discharges hydrogen in the recirculation line to the outside as the outlet is opened. A recirculation determining processor determines a recirculation state of the recirculation line and a concentration estimator estimates a purge amount for each gas, which is purged by the purge valve, based on the determined recirculation state and estimates a concentration of hydrogen in the recirculation line based on the estimated purge amount for each gas.

A fuel cell system includes a fuel cell a current sensor that detects a current of the fuel cell, a plurality of cell voltage sensors that detects a voltage in a unit of one or two or more cells of the fuel cell among the cells, a pump that adjusts a flow rate of the cooling medium, and a controller. The controller estimates, in a first case, a calorific value of the fuel cell using each detected cell voltage value and the detected current value, decides the flow rate of the cooling medium based on the estimated calorific value, and controls the operation of the pump such that the flow rate of the cooling medium is lower than that of a case where the estimated calorific value is the same in a normal operation of the fuel cell.

An output voltage prediction system for a fuel cell includes: a storage unit that stores a relationship between a logarithm of a cumulative deterioration index amount and an output voltage of the fuel cell when an output current of the fuel cell is within a predetermined current range, the cumulative deterioration index amount being a cumulative amount of a deterioration index amount related to progress of deterioration of the fuel cell; an input data acquisition unit that acquires the cumulative deterioration index amount of the fuel cell as input data; and a prediction unit that converts the input data acquired by the input data acquisition unit into a logarithm and predicts the output voltage of the fuel cell based on the logarithm of the input data and the relationship stored in the storage unit.

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.

Some embodiments of the disclosure provide a cathode circulation system of a fuel cell connected to a power generation unit of the fuel cell. The cathode circulation system includes a first gas supply tank for providing an inert gas, a second gas supply tank for providing a reaction gas, a mixing tank connected to the first gas supply tank and the second gas supply tank for mixing the inert gas and the reaction gas, a gas-liquid separator connected to the power generation unit, and at least one cathode gas pump provided between the mixing tank and the gas-liquid separator and between the mixing tank and the power generation unit.