Abstract: A control method for a fuel cell stop mode is provided. The method includes measuring an air flow rate supplied to a fuel cell stack and when a fuel cell stop mode is entered, determining an oxygen distribution state between cells included in the fuel cell stack based on the measured air flow rate. Air supply is then supplied to the fuel cell stack or the air supply to the fuel cell stack is interrupted based on the determined oxygen distribution state.

Abstract: A method for controlling a fuel cell vehicle is provided. The method includes setting a target purge degree of an anode gas and a target opening degree of an air pressure control valve and determining whether a fuel cell stack is in a power generation stop state. When the fuel cell stack is in the power generation stop state, when the anode gas is purged from the anode based on the target purge degree and the target opening degree, whether hydrogen in the anode gas will flow backwards to a stack enclosure is determined. When the hydrogen flows backwards, at least one of the target purge degree and the target opening degree to a level at which the backflow of the hydrogen is prevented is modified, and the anode gas from the anode based on the modified target purge degree and the modified target opening degree is purged.

Abstract: A control method for driving of a fuel cell is provided. The method includes determining whether power generation of the fuel cell is stopped and when the power generation of the fuel cell is stopped, monitoring voltages of multiple unit cells included in the fuel cell. A degree of defect of the unit cells is determined based on the monitored voltages of the unit cells.

Abstract: The present disclosure provides a method of determining a coolant condition of a vehicle, and more particularly, a method of accurately determining a coolant condition, e.g., a condition in which gas is present in a system and an insufficient coolant condition without a separate additional sensor in a vehicle using an electric water pump (EWP). To this end, the present disclosure provides a method of determining a coolant condition of a vehicle, including, in a vehicle including an electric water pump (EWP) for circulating a coolant, acquiring driving state information of a water pump while the water pump is driven, by a controller, calculating a ripple value of a driving state from the acquired driving state information of the water pump, by the controller, and comparing the calculated ripple value with a reference value to determine a condition of a coolant, by the controller.

Abstract: A fuel cell system for modulating an offset of a hydrogen pressure sensor is provided. The fuel cell system includes a stack with a plurality of cells and each cells includes a first electrode to which hydrogen is supplied, a second electrode to which oxygen is supplied, and a membrane electrode assembly arranged between the first and second electrodes to produce electricity by reaction between the hydrogen and the oxygen. The hydrogen pressure sensor is connected to each cell to sense a pressure of the hydrogen supplied to the first electrode. A controller that which of the cells is supplied with insufficient pressure of hydrogen and modulates the offset of the hydrogen pressure sensor connected to the cell to which the hydrogen is supplied with insufficient pressure, to then supply the hydrogen to the first electrode at an appropriate pressure.

Abstract: A method for diagnosing a lack of coolant includes: (a) determining whether a target revolution per minute (RPM) of a coolant pump is set to be constantly maintained for a first time, which is preset, or more, (b) calculating an actual average RPM and an actual average driving current of the coolant pump for a second time, which is preset to be shorter than the first time, when the target RPM is set to be constantly maintained for the first time, and (c) determining whether the coolant to be supplied to the coolant pump is insufficient, based on the actual average RPM and the actual average driving current.

Abstract: A method for diagnosing a water-containing state of a fuel cell stack includes steps of: applying an alternating current (AC) signal having a predetermined frequency to the fuel cell stack to calculate each of an electrolyte membrane impedance, an anode impedance, and a cathode impedance from an output voltage and an output current of the fuel cell stack corresponding to the AC signal; and diagnosing the water-containing state of the fuel cell stack on the basis of the electrolyte membrane impedance, the anode impedance, and the cathode impedance.

Abstract: A control method for driving of a fuel cell is provided. The method includes determining whether power generation of the fuel cell is stopped and when the power generation of the fuel cell is stopped, monitoring voltages of multiple unit cells included in the fuel cell. A degree of defect of the unit cells is determined based on the monitored voltages of the unit cells.

Abstract: A method for controlling a fuel cell vehicle is provided. The method includes setting a target purge degree of an anode gas and a target opening degree of an air pressure control valve and determining whether a fuel cell stack is in a power generation stop state. When the fuel cell stack is in the power generation stop state, when the anode gas is purged from the anode based on the target purge degree and the target opening degree, whether hydrogen in the anode gas will flow backwards to a stack enclosure is determined. When the hydrogen flows backwards, at least one of the target purge degree and the target opening degree to a level at which the backflow of the hydrogen is prevented is modified, and the anode gas from the anode based on the modified target purge degree and the modified target opening degree is purged.

Abstract: An apparatus for diagnosing a fuel cell and a vehicle system includes a measuring device that measures a stack voltage and a stack current from a fuel cell stack, and at least one processor that extracts a plurality of reference current points and a plurality of reference voltage points corresponding to the reference current points by analyzing the measured stack voltage and the measured stack current, calculates an abnormality degree of the fuel cell stack based on a reference signal waveform formed by using voltage differences between the reference voltage points, and determines an abnormal state of the fuel cell stack based on the calculated abnormality degree of the fuel cell stack.

Abstract: A method for controlling a fuel cell vehicle is provided. The method includes setting a target purge degree of an anode gas and a target opening degree of an air pressure control valve and determining whether a fuel cell stack is in a power generation stop state. When the fuel cell stack is in the power generation stop state, when the anode gas is purged from the anode based on the target purge degree and the target opening degree, whether hydrogen in the anode gas will flow backwards to a stack enclosure is determined. When the hydrogen flows backwards, at least one of the target purge degree and the target opening degree to a level at which the backflow of the hydrogen is prevented is modified, and the anode gas from the anode based on the modified target purge degree and the modified target opening degree is purged.

Abstract: A control method for a fuel cell stop mode is provided. The method includes measuring an air flow rate supplied to a fuel cell stack and when a fuel cell stop mode is entered, determining an oxygen distribution state between cells included in the fuel cell stack based on the measured air flow rate. Air supply is then supplied to the fuel cell stack or the air supply to the fuel cell stack is interrupted based on the determined oxygen distribution state.

Abstract: A method for controlling a fuel cell system includes steps of: (a) determining whether hydrogen (H2) is detected in an interior space of a stack enclosure in which a fuel cell stack is accommodated; (b) stopping power generation that is performed using the stack when it is determined in step (a) that the hydrogen is detected; (c) opening a purge valve to discharge gases circulating in an anode through the purge valve, and opening a condensate discharge valve to discharge condensate contained in a water trap through the condensate discharge valve; and (d) determining whether the hydrogen discharged through at least one of the purge valve and the condensate discharge valve in step (c) flows back to the interior space based on H2 concentration in the interior space.

Abstract: The present disclosure provides a method of determining a coolant condition of a vehicle, and more particularly, a method of accurately determining a coolant condition, e.g., a condition in which gas is present in a system and an insufficient coolant condition without a separate additional sensor in a vehicle using an electric water pump (EWP). To this end, the present disclosure provides a method of determining a coolant condition of a vehicle, including, in a vehicle including an electric water pump (EWP) for circulating a coolant, acquiring driving state information of a water pump while the water pump is driven, by a controller, calculating a ripple value of a driving state from the acquired driving state information of the water pump, by the controller, and comparing the calculated ripple value with a reference value to determine a condition of a coolant, by the controller.

Abstract: A fuel cell system for modulating an offset of a hydrogen pressure sensor is provided. The fuel cell system includes a stack with a plurality of cells and each cells includes a first electrode to which hydrogen is supplied, a second electrode to which oxygen is supplied, and a membrane electrode assembly arranged between the first and second electrodes to produce electricity by reaction between the hydrogen and the oxygen. The hydrogen pressure sensor is connected to each cell to sense a pressure of the hydrogen supplied to the first electrode. A controller that which of the cells is supplied with insufficient pressure of hydrogen and modulates the offset of the hydrogen pressure sensor connected to the cell to which the hydrogen is supplied with insufficient pressure, to then supply the hydrogen to the first electrode at an appropriate pressure.

Abstract: A method of controlling energy supply in a fuel cell vehicle includes storing an output current of a fuel cell as a pre-limited current when a cell voltage ratio reaches a minimum cell voltage ratio, setting a limited output current of the fuel cell as the pre-limited current when the cell voltage ratio reaches a hazard cell voltage ratio, connecting first and second high-voltage batteries to a main bus terminal in parallel when the cell voltage ratio reaches the hazard cell voltage ratio, and outputting a supplementary current from the second high-voltage battery by an insufficient amount of the output current of the fuel cell for the pre-limited current, and a system for performing the same.

Abstract: A method for diagnosing a lack of coolant includes: (a) determining whether a target revolution per minute (RPM) of a coolant pump is set to be constantly maintained for a first time, which is preset, or more, (b) calculating an actual average RPM and an actual average driving current of the coolant pump for a second time, which is preset to be shorter than the first time, when the target RPM is set to be constantly maintained for the first time, and (c) determining whether the coolant to be supplied to the coolant pump is insufficient, based on the actual average RPM and the actual average driving current

Abstract: A method for diagnosing a water-containing state of a fuel cell stack includes steps of: applying an alternating current (AC) signal having a predetermined frequency to the fuel cell stack to calculate each of an electrolyte membrane impedance, an anode impedance, and a cathode impedance from an output voltage and an output current of the fuel cell stack corresponding to the AC signal; and diagnosing the water-containing state of the fuel cell stack on the basis of the electrolyte membrane impedance, the anode impedance, and the cathode impedance.

Abstract: A method for controlling a fuel cell vehicle is provided. The method includes setting a target purge degree of an anode gas and a target opening degree of an air pressure control valve and determining whether a fuel cell stack is in a power generation stop state. When the fuel cell stack is in the power generation stop state, when the anode gas is purged from the anode based on the target purge degree and the target opening degree, whether hydrogen in the anode gas will flow backwards to a stack enclosure is determined. When the hydrogen flows backwards, at least one of the target purge degree and the target opening degree to a level at which the backflow of the hydrogen is prevented is modified, and the anode gas from the anode based on the modified target purge degree and the modified target opening degree is purged.

Abstract: An apparatus and a method for controlling vehicle start-up modify a sequence order in which control units of the vehicle are started up to improve reliability. In operation, a processor determines whether a voltage of a low-voltage battery is less than a reference voltage when a start key is turned on, and determines a voltage classification level corresponding to the voltage of the low-voltage battery when the voltage of the low-voltage battery is less than or equal to the reference voltage. The processor then determines a sequence order in which to start up driving units of the vehicle including a power conversion device of the vehicle based on the determined voltage classification level, and controls startup of the vehicle by reflecting the determined sequence order of the power conversion device.