Abstract: A control method and system of a fuel cell system are provided. The control method includes draining the voltage of a fuel cell stack by charging a high voltage battery. In addition, the method includes draining the voltage of the fuel cell stack by connecting a fuel cell load device to the fuel cell stack, which is performed when the voltage of the fuel cell stack decreased by the first draining process is less than a predetermined first reference voltage.

Abstract: An apparatus and method for controlling hydrogen purging are provided. The hydrogen purging control apparatus includes a purge valve that is disposed at an outlet on an anode side of a fuel cell stack and is configured to adjust an amount of emission of hydrogen containing impurities. Additionally, a controller is configured to adjust an opening and closing cycle of the purge valve based on a required output or an output current of the fuel cell stack.

Abstract: An apparatus and method for controlling hydrogen purging are provided. The hydrogen purging control apparatus includes a purge valve that is disposed at an outlet on an anode side of a fuel cell stack and is configured to adjust an amount of emission of hydrogen containing impurities. Additionally, a controller is configured to adjust an opening and closing cycle of the purge valve based on a required output or an output current of the fuel cell stack.

Abstract: An apparatus and method for controlling hydrogen purging are provided. The hydrogen purging control apparatus includes a purge valve that is disposed at an outlet on an anode side of a fuel cell stack and is configured to adjust an amount of emission of hydrogen containing impurities. Additionally, a controller is configured to adjust an opening and closing cycle of the purge valve based on a required output or an output current of the fuel cell stack.

Abstract: A method of controlling the operation of a fuel cell system is provided. The method includes diagnosing a water shortage state in a fuel cell stack based on degradation of cooling performance and deterioration of the fuel cell stack and determining a diagnosis level of the fuel cell system based on the diagnosed water shortage state of the fuel cell stack. In addition, a regenerative operation is performed by selecting a regenerative operation mode which corresponds to the determined diagnosis level.

Abstract: A technique of diagnosing a fuel cell stack is provided. In particular, current and voltage of a fuel cell stack are measured during driving of a fuel cell vehicle and the current and voltage are sequentially stored. It is then determined based on the stored current whether the vehicle is being operated at constant current. Different factors are analyzed depending on whether the vehicle is being operated at constant current, and then it is determined whether the fuel cell stack is in a normal state. A moisture supply into the fuel cell stack is calculated if it is determined that the fuel cell stack is not in the normal state. Based on the calculated moisture supply, whether the fuel cell stack is in a dryout state is diagnosed.

Abstract: A method and system for controlling a voltage in a stop-mode of a fuel cell vehicle are provided. The method includes detecting whether a fuel cell enters the stop-mode and calculating a voltage command value of a bus terminal based on available charging power of a battery representing a level of power chargeable in a high voltage battery when the fuel cell enters the stop-mode. A converter connected between the high voltage battery and the bus terminal is operated to adjust the voltage of the bus terminal to be the voltage command value of the bus terminal. Additionally, power consumption of an electric field load of a vehicle is increased when the voltage is adjusted and then the voltage of the fuel cell measured by a voltage sensor is equal to or greater than a reference voltage preset in a memory.

Abstract: A control method and system of a fuel cell system are provided. The control method includes draining the voltage of a fuel cell stack by charging a high voltage battery. In addition, the method includes draining the voltage of the fuel cell stack by connecting a fuel cell load device to the fuel cell stack, which is performed when the voltage of the fuel cell stack decreased by the first draining process is less than a predetermined first reference voltage.

Abstract: A power net system of a fuel cell vehicle is provided. The power net system includes a fuel cell and a high-voltage battery unit connected in parallel via a main bus and a first switching unit that is configured to form and block an electrical connection between an output terminal of the fuel cell and the main bus. A load device diverges and is connected between the output terminal of the fuel cell and the first switching unit. A reverse current blocking unit is connected between the first switching unit and a node from which the load device diverges. A second switching unit is configured to form and block an electrical connection between the output terminal of the fuel cell and the load device. A controller operates the first and second switching units and adjusts the electrical connection state between the main bus and the high-voltage battery unit.

Abstract: A control method and system of a fuel cell system are provided. The control method includes draining the voltage of a fuel cell stack by charging a high voltage battery. In addition, the method includes draining the voltage of the fuel cell stack by connecting a fuel cell load device to the fuel cell stack, which is performed when the voltage of the fuel cell stack decreased by the first draining process is less than a predetermined first reference voltage.

Abstract: A method for controlling startup of a fuel cell vehicle is provided. The disclosed method includes detecting generation of a startup command from a vehicle and supplying hydrogen to a fuel cell by opening a hydrogen valve. Additionally, the method includes detecting whether a fuel cell voltage has increased after supply of hydrogen, and a first startup of consuming generated electric power of the fuel cell through connection of a load device to the fuel cell, supplying air to the fuel cell through opening an air valve and adjusting the fuel cell voltage to be maintained at a predetermined level or less through adjustment of a bus stage voltage of a power converter when the controller determines that the fuel cell voltage has increased after supply of hydrogen.

Abstract: A system and method for controlling a fuel cell of a vehicle are provided. The method includes sensing a time point when pressure control is necessary by sensing whether an output of the fuel cell is additionally necessary or whether the fuel cell can be in a dry-out state. In response to sensing that the pressure control is necessary, a required valve opening degree of an air outlet is derived by substituting a target air pressure for a data map. A fuel cell air outlet valve is then adjusted based the derived valve opening degree of the air outlet.

Abstract: A fuel cell system and a method of controlling the fuel cell system are provided. The fuel cell system includes at least one bypass valve that is disposed between a passage in an inlet of a fuel cell stack and a bypass passage that is branched from the passage within the inlet and that is connected to a discharge port of the fuel cell stack. In addition, a controller bypasses air supplied from an air blower to the discharge port by adjusting an opening degree of the bypass valve.

Abstract: A control method and system of a fuel cell system is provided. The control method includes detecting, by a controller, a voltage of a fuel cell stack when power generation of a fuel cell is stopped while a fuel cell vehicle is being driven. In addition, hydrogen supply pressure at an anode side is adjusted based on a variation in the detected voltage.

Abstract: A technique of diagnosing a fuel cell stack is provided. In particular, current and voltage of a fuel cell stack are measured during driving of a fuel cell vehicle and the current and voltage are sequentially stored. It is then determined based on the stored current whether the vehicle is being operated at constant current. Different factors are analyzed depending on whether the vehicle is being operated at constant current, and then it is determined whether the fuel cell stack is in a normal state. A moisture supply into the fuel cell stack is calculated if it is determined that the fuel cell stack is not in the normal state. Based on the calculated moisture supply, whether the fuel cell stack is in a dryout state is diagnosed.

Abstract: An apparatus and method for controlling hydrogen purging are provided. The apparatus includes a purging valve that is provided for an outlet disposed adjacent to an anode of a fuel cell stack and is configured to adjust an outflow of water from the fuel cell stack. In addition, a controller is configured to adjust an opening of the purging valve according to a charge capacity obtained by integrating a current of the fuel cell stack. The controller is configured to calculate the charge capacity by multiplying the current of the fuel cell stack by a scale factor when a load for an output current of the fuel cell stack is less than a first reference load which is preset.

Abstract: A system and method for controlling power of a fuel cell for a vehicle are provided. The method includes measuring a temperature of the fuel cell and when the measured temperature of the fuel cell is within a high temperature range in which a power threshold value of the fuel cell is reduced based on an increase in temperature of the fuel cell and when the measured temperature of the fuel cell is increased and then is equal to or greater than a predetermined temperature a power threshold value is reduced from a power value at the predetermined temperature. The high temperature range is a range between a third temperature at which the power threshold value starts to be reduced based on the increase in temperature of the fuel cell and a fourth temperature at which the power threshold value is reduced and then reaches the minimum power threshold value.

Abstract: A power net system of a fuel cell vehicle is provided. The power net system includes a fuel cell and a first switching unit that is configured to form and block an electrical connection between an output terminal of the fuel cell and a main bus. A load device diverges and is connected between the output terminal and the first switching unit. A reverse current blocking unit is disposed between the output terminal of the fuel cell and a node from which the load device diverges and is configured to block a current flow to the output terminal of the fuel cell. A second switching unit is configured to form and block an electrical connection between the output terminal of the fuel cell and the load device. A controller operates the first and second switching units to form the electrical connection between the main bus and the load device.

Abstract: A power net system for a fuel cell vehicle includes: a diode having a first end connected to an output stage of a fuel cell stack; a fuel cell load device branched and connected between the output stage of the fuel cell stack and the diode; a first relay positioned between the output stage of the fuel cell stack and the fuel cell load device and configured to connect or separate the output stage of the fuel cell stack and the fuel cell load device; and a second relay having a first end connected to a second end of the diode and a second end connected between the first relay and the fuel cell load device.

Abstract: A system and method for controlling a temperature of a fuel cell stack are provided. The method includes performing a pump OFF mode which turns off the cooling water pump or operates the cooling water pump while reducing the rotation speed of the cooling water pump to be less than the reference rotation speed, when a cooling water outlet temperature is equal to or less than a preset first temperature while a pump normal mode which adjusts a rotation speed of a cooling water pump to be equal to or greater than a preset reference rotation speed and varies rpm based on the cooling water outlet temperature is performed. In addition, the pump normal mode is performed when a cooling water outlet temperature estimation value of the fuel cell stack exceeds a preset second temperature while the pump OFF mode is performed.