A method and system for controlling air flow is arranged to reduce power consumption of an air blower or an air compressor by controlling air flow, enhance stack performance by preventing stack dry-out that is more likely to occur in a low-flow range, and improve durability of the stack by decreasing frequency of exposure to high voltages.

A method of determining hydrogen deficiency of a fuel cell having a plurality of cell groups includes a reference value storage step of storing, as a reference value, a value of impedance in a state where hydrogen-off gas is discharged from the fuel cell and hydrogen gas and oxidant gas are supplied, a measured value calculation step of calculating a measured value of impedance based on a voltage of the cell groups and a current of the fuel cell, a corrected value calculation step of calculating a corrected value of impedance by correcting the measured value based on the reference value, and a determination step of determining that hydrogen deficiency occurs in a case where the corrected value exceeds a predetermined threshold.

A device for detecting a current leakage and a current leakage detection system including the same are provided. The device for detecting a current leakage includes a magnetic core having an internal space and both ends the core are separated from each other. An electric wiring extends to pass through the internal space of the magnetic core, and is connected between a power source and an electric load to supply power from the power source to the electric load. A hall sensor senses a magnetic field induced in the magnetic core.

A power converter for a fuel cell is provided. The power converter includes a boost converter connected to the fuel cell and configured to control a load voltage at a predetermined magnitude in a normal operation mode and to induce an output response by applying a predetermined perturbation current to the fuel cell in a diagnosis mode, and a digital signal processor configured to extract an impedance parameter by detecting the output response of the fuel cell in the diagnosis mode, and predict a lifespan of the fuel cell according to the impedance parameter. The normal operation mode is configured to supply a voltage in response to a change of a load and the diagnosis mode is configured to predict the lifespan of the fuel cell.

A method for controlling a fuel cell system including a fuel cell, includes measuring an impedance of the fuel cell that includes a solid polymer electrolyte membrane to generate electric power via an electrochemical reaction between a fuel gas and an oxidant gas. An output electric current output from the fuel cell is increased to a threshold electric current value when the impedance is equal to or higher than a threshold impedance value and a target electric current value is larger than the threshold electric current value. The output electric current is maintained at the threshold electric current value. The output electric current is increased from the threshold electric current value to the target electric current value.

A method for controlling a fuel cell system including a fuel cell, includes generating electric current via an electrochemical reaction between a fuel gas and an oxidant gas by the fuel cell including a solid polymer electrolyte membrane. An impedance of the fuel cell is detected. It is determined whether the impedance reaches a threshold impedance. The electric current generated by the fuel cell is increased when the impedance is determined to reach the threshold impedance.

A power supply system includes a power supply, a conversion module, and a processor. The conversion module includes conversion units to convert, based on a first control signal, voltage of electric power supplied from the power supply. The conversion units are electrically connected in parallel. The processor is configured to change a number of operating conversion unit among the conversion units. The processor is configured to generate the first control signal to generate a DC component in the electric power output from the power supply. The processor is configured to generate a second control signal to detect a state of the power supply. An AC component is generated according to the second control signal in the electric power output from the power supply such that the AC component has an amplitude based on the number of operating conversion unit.

A power supply system includes a power supply, a converter, and a processor. The converter converts voltage of the electric power supplied from the power supply. The processor is configured to generate a first control signal to control the converter to output a target voltage or a target current via a feedback control based on the first control signal. The processor is configured to generate a second control signal to detect a state of the power supply. The processor is configured to combine the first control signal and the second control signal to control the converter.

A state determination device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising: an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; and an anode reaction resistance estimation/calculation unit configured to calculate an estimation value of a reaction resistance of an anode electrode of the fuel cell on the basis of a measurement value of the internal impedance, wherein: the predetermined frequency is selected such that a difference between the estimation value of the reaction resistance of the anode electrode during hydrogen starvation and the estimation value of the reaction resistance of the anode electrode during oxygen starvation is not smaller than a predetermined value.

A fuel cell stack includes a plurality of cell groups and a controller wherein each cell group comprises a plurality of fuel cells and a group sensor which measures one or more electrical characteristics of the respective cell group. The controller comprises one or more processors and memory and is communicatively coupled to each group sensor. The one or more processors execute machine readable instructions to compare a measured electrical characteristic of each cell group to one or more thresholds stored in memory, and indicate the need for diagnostics of the fuel cell stack when the comparison indicates a non-systemic event.