An ECU of a fuel cell vehicle determines whether the vehicle travels on an uphill road or not. When determining that the vehicle travels on the uphill road, the ECU performs at least one of a temperature reduction control for reducing the temperature of a fuel cell stack and a humidification control for increasing the water content of the fuel cell stack, by the time the vehicle reaches the uphill road.

In a case where each of the temperature, the impedance, and the output current of a fuel cell stack falls within a predetermined range, the output voltage of the fuel cell stack is measured, and the measured output voltage is compared with a reference value to thereby determine the degree of degradation of the fuel cell stack.

A fuel cell system and method, the system including a hotbox, a fuel cell stack disposed in the hotbox, an anode tail gas oxidizer (ATO) disposed in the hotbox, and a fuel exhaust processor fluidly connected to the hotbox. The fuel exhaust processor includes a first hydrogen pump configured to extract hydrogen from the anode exhaust received from the fuel cell stack and to output the hydrogen to a first hydrogen stream provided to the fuel cell stack, a second hydrogen pump configured to extract hydrogen from anode exhaust output from the first hydrogen pump and to output the hydrogen to the first hydrogen stream, and a third hydrogen pump configured to extract hydrogen from anode exhaust output from the second hydrogen pump and to output the hydrogen to a second hydrogen stream provided to the ATO.

Disclosed are an apparatus for measuring an impedance of a fuel cell in a system to which a DC-DC converter is applied and a method thereof. The method includes calculating an impedance of a fuel cell stack based on an impedance of an output terminal of the fuel cell stack measured in a state in which the output of the fuel cell stack is drawn and the impedance of the output terminal of the fuel cell stack measured in a state in which the drawing of the output of the fuel cell stack is stopped.

Disclosed are a device and a method for controlling a fuel cell system, in which during operation of the fuel cell system, the device and method determine a minimum motoring current limit value applied to a motor for driving a fuel cell vehicle by varying an output current limit threshold value of the fuel cell stack by determining an available output current of the stack and by varying an available voltage lower limit threshold value of the stack by determining an available operating voltage of the stack, thereby preventing the fuel cell vehicle from rattling due to excessive limitation of output current of the stack. They also control the pressures of an anode and a cathode of the stack by monitoring whether the performance of the stack is degraded as limitation of output current of the stack is suppressed, thereby suppressing degradation of the performance of the stack.

A fuel cell system includes a first converter to convert power, which is output from a fuel cell stack or a battery, into power in a specific level, a second converter to convert power which is input to or output from the battery, a power relay assembly to control power flow between a super capacitor and the first converter, and a controller to control outputs of the first converter and the second converter, depending on a starting state or an operating state of the fuel cell system, and to control an operation of the power relay assembly.

Systems and methods for monitoring the isolation resistance of one or more fuel cells are described herein. In one example, a system includes a current transformer having a hollow core. First and second portions of a load line from a fuel cell are located within the hollow core. The first portion of the load line is electrically between an anode of a fuel cell and an electrical load, while the second portion of the load line being electrically between a cathode of the fuel cell and the electrical load. The current transformer is configured to output an electrical signal proportional to a current passing through the hollow core. This electrical signal can then be used to determine the isolation resistance of the fuel cell.

According to the present embodiment, the first fuel cell group is formed of a plurality of fuel cell stacks connected in series. The first power converter is capable of controlling a first power to be generated by the first fuel cell group according to a first output current. The second fuel cell group is formed of a plurality of fuel cell stacks connected in series, the fuel cell stacks corresponding respectively to the fuel cell stacks in the first fuel cell group. The second power converter is capable of controlling a second power to be generated by the second fuel cell group according to a second output current. Oxygen-containing gas is supplied through the first pipe to each of the fuel cell stacks in the first fuel cell group and each of the fuel cell stacks in the second fuel cell group.

A method conditions a fuel cell stack of a fuel cell system during a usage operation of the fuel cell system. The method determines that a conditioning of the fuel cell stack is to be carried out for increasing an electrical power provided by the fuel cell stack during usage operation. In addition, the method adjusts at least one operating parameter of the fuel cell system in order to increase a current flow through the fuel cell stack for conditioning the fuel cell stack during usage operation.

To provide a fuel cell system capable of evaluating degradation of an electrolyte membrane by quantifying metal ions involved in degradation of an electrolyte membrane instead of evaluating degradation of an electrolyte membrane itself. A fuel cell system comprising a fuel cell, a fuel gas system for supplying fuel gas to an anode of the fuel cell, an oxidant gas system for supplying oxidant gas to a cathode of the fuel cell, a voltage detector for detecting a voltage of the fuel cell, and a controller.