Abstract: A method for determining a sealing tightness of a fuel cell stack includes providing of fuel into a cathode space, sealed off gas-tight against further components of a cathode subsystem, formed at least partly by the fuel cell stack, and detecting of a value which is indicative of a pressure change in the cathode space, where a cathode test pressure in the cathode space is higher than a pressure outside the fuel cell stack.

Abstract: A method for operating a fuel cell system includes delivering an oxidant to at least one fuel cell by at least one oxidant delivery device where the stoichiometric ratio of the oxidant is modified on the basis of the delivery rate of the oxidant delivery device.

Abstract: A method for determining a sealing tightness of a fuel cell stack includes providing of fuel into a cathode space, sealed off gas-tight against further components of a cathode subsystem, formed at least partly by the fuel cell stack, and detecting of a value which is indicative of a pressure change in the cathode space, where a cathode test pressure in the cathode space is higher than a pressure outside the fuel cell stack.

Abstract: A method for operating a fuel cell system includes delivering an oxidant to at least one fuel cell by at least one oxidant delivery device where the stoichiometric ratio of the oxidant is modified on the basis of the delivery rate of the oxidant delivery device.

Abstract: A cooling system for a fuel cell of a fuel cell system includes a cooling circuit that includes at least one heat exchanger and the fuel cell. The cooling system also includes at least two pumping devices, arranged in the cooling circuit, whereby the at least two pumping devices at least sometimes jointly deliver coolant into the cooling circuit.

Abstract: A system for conditioning the air in a passenger compartment of a fuel cell-powered vehicle is provided, the system including a metal hydride buffer and a hydrogen source, wherein the metal hydride buffer reversibly adsorbs and desorbs hydrogen gas. The change in temperature associated with adsorption or desorption of the hydrogen gas by the metal hydride buffer is thermally communicated to the passenger compartment, thereby conditioning the air therein. Desorbed hydrogen gas is fed back to the fuel cell to power the vehicle. Also provided are a vehicle having a system for conditioning air in a passenger compartment that employs the change in temperature resulting from the adsorption and desorption of hydrogen gas by the metal hydride buffer and methods for heating or cooling a passenger compartment of a fuel cell-powered vehicle.

Abstract: A fuel cell assembly having a flow distribution subassembly that comprises four sets of flow channels, the first set facing an anode for distribution of a fuel reactant to said anode, the second set facing a cathode for distribution of an oxidant to said cathode, the third set in flow communication with said second set and in heat transfer relation with at least one of said anode and said cathode, and the fourth set receiving a coolant different from said oxidant.

Abstract: A method and system for controlling temperature in an electric vehicle battery pack which preserves battery pack performance and longevity while maximizing vehicle driving range. A controller prescribes a minimum allowable operating temperature in the battery pack, where the minimum operating temperature increases as battery pack state of charge and remaining useful life decrease. During vehicle driving operations, the minimum allowable temperature is computed, and a thermal management system is used to warm the battery pack only if necessary to raise its temperature above the calculated minimum level. By minimizing use of the thermal management system to warm the battery pack, energy consumption is reduced and vehicle driving range is increased, while not adversely affecting battery pack performance or durability. The same strategy is employed during charging, which reduces the amount of energy consumed from the grid for warming the battery pack.

Abstract: A system and method for controlling the bleed valve in an anode recirculation loop of a fuel cell system. The system uses a model to determine the concentration of hydrogen in the recirculated gas by calculating the volume flow of the recirculated gas through a fuel cell stack, a pressure drop across the anode inlet and outlet of the stack, and the density of the recirculated gas, and using a measured temperature of the recirculated gas and a measured pressure drop across a recirculation pump.

Abstract: A system and method for controlling the speed of a recirculation pump in an anode recirculation loop of a fuel cell system based on a predetermined ratio of fresh hydrogen to recirculated anode gas. The system uses a model to determine the volume flow of the recirculated gas through a fuel cell stack to determine the recirculation rate based on a measured temperature of the recirculated gas, a measured pressure drop across a recirculation pump, a pressure drop across the anode inlet and outlet of the stack, a percentage of hydrogen in the recirculated gas, and the density of the recirculated gas.

Abstract: A method and system for controlling temperature in an electric vehicle battery pack which preserves battery pack performance and longevity while maximizing vehicle driving range. A controller prescribes a minimum allowable operating temperature in the battery pack, where the minimum operating temperature increases as battery pack state of charge and remaining useful life decrease. During vehicle driving operations, the minimum allowable temperature is computed, and a thermal management system is used to warm the battery pack only if necessary to raise its temperature above the calculated minimum level. By minimizing use of the thermal management system to warm the battery pack, energy consumption is reduced and vehicle driving range is increased, while not adversely affecting battery pack performance or durability. The same strategy is employed during charging, which reduces the amount of energy consumed from the grid for warming the battery pack.

Abstract: A fuel cell assembly having a flow distribution subassembly that comprises four sets of flow channels, the first set facing an anode for distribution of a fuel reactant to said anode, the second set facing a cathode for distribution of an oxidant to said cathode, the third set in flow communication with said second set and in heat transfer relation with at least one of said anode and said cathode, and the fourth set receiving a coolant different from said oxidant.

Abstract: A propulsion system for a fuel cell hybrid vehicle that includes a fuel cell system and an EESS, where the propulsion system employs an algorithm for increasing system efficiency. A power limit value is defined as the maximum system efficiency times the charge/discharge efficiency of the EESS. If the vehicle operator requests a power greater than the power limit value, then the fuel cell system will preferably provide the power, and if the power request from the vehicle operator is less than the power limit value, then the EESS will preferably provide the power. The algorithm also considers changing operation conditions and parameters that impact the fuel cell system efficiency and the electric energy storage system efficiency, such as the state of charge of the EESS and regenerative braking.

Abstract: A fuel cell assembly having a flow distribution subassembly that comprises four sets of flow channels, the first set facing an anode for distribution of a fuel reactant to said anode, the second set facing a cathode for distribution of an oxidant to said cathode, the third set in flow communication with said second set and in heat transfer relation with at least one of said anode and said cathode, and the fourth set receiving a coolant different from said oxidant.

Abstract: A fuel cell system employing a floating base load hybrid strategy for reducing fast voltage transients of a FCPM. A power request signal is applied to an average power calculation processor that calculates the average power requested over a predetermined previous period of time. A weighting function processor provides a weighting function based on the state of charge of an EESS. The power available from the FCPM and the EESS is applied to a power comparison processor. The available power is compared to the power request to provide a difference value between what is currently being provided and what is desired. The difference value is compared to power limit values of the EESS. The output value of this comparison is added to a filtered value to generate a signal for the change in the output power of the fuel cell stack based on the power request.

Abstract: A fuel cell system employing a floating base load hybrid strategy for reducing fast voltage transients of a FCPM. A power request signal is applied to an average power calculation processor that calculates the average power requested over a predetermined previous period of time. A weighting function processor provides a weighting function based on the state of charge of an EESS. The power available from the FCPM and the EESS is applied to a power comparison processor. The available power is compared to the power request to provide a difference value between what is currently being provided and what is desired. The difference value is compared to power limit values of the EESS. The output value of this comparison is added to a filtered value to generate a signal for the change in the output power of the fuel cell stack based on the power request.

Abstract: A system and method for controlling the speed of a recirculation pump in an anode recirculation loop of a fuel cell system based on a predetermined ratio of fresh hydrogen to recirculated anode gas. The system uses a model to determine the volume flow of the recirculated gas through a fuel cell stack to determine the recirculation rate based on a measured temperature of the recirculated gas, a measured pressure drop across a recirculation pump, a pressure drop across the anode inlet and outlet of the stack, a percentage of hydrogen in the recirculated gas, and the density of the recirculated gas.

Abstract: A system and method for controlling the bleed valve in an anode recirculation loop of a fuel cell system. The system uses a model to determine the concentration of hydrogen in the recirculated gas by calculating the volume flow of the recirculated gas through a fuel cell stack, a pressure drop across the anode inlet and outlet of the stack, and the density of the recirculated gas, and using a measured temperature of the recirculated gas and a measured pressure drop across a recirculation pump.

Abstract: A fuel cell system employing a floating base load hybrid strategy for reducing fast voltage transients of a FCPM. A power request signal is applied to an average power calculation processor that calculates the average power requested over a predetermined previous period of time. A weighting function processor provides a weighting function based on the state of charge of an EESS. The power available from the FCPM and the EESS is applied to a power comparison processor. The available power is compared to the power request to provide a difference value between what is currently being provided and what is desired. The difference value is compared to power limit values of the EESS. The output value of this comparison is added to a filtered value to generate a signal for the change in the output power of the fuel cell stack based on the power request.

Abstract: A propulsion system for a fuel cell hybrid vehicle that includes a fuel cell system and an EESS, where the propulsion system employs an algorithm for increasing system efficiency. A power limit value is defined as the maximum system efficiency times the charge/discharge efficiency of the EESS. If the vehicle operator requests a power greater than the power limit value, then the fuel cell system will preferably provide the power, and if the power request from the vehicle operator is less than the power limit value, then the EESS will preferably provide the power. The algorithm also considers changing operation conditions and parameters that impact the fuel cell system efficiency and the electric energy storage system efficiency, such as the state of charge of the EESS and regenerative braking.