Abstract: A fuel cell system and method of operation in which the fuel cell system has a fuel cell unit with anode and cathode, a media flow path for supplying substantially pure hydrogen to the anode, a media flow path for the cathode, an anode exhaust-gas flow path and a cathode exhaust-gas flow path. A fan for supplying air to the cathode is provided in the flow path of the cathode, and a catalytic burner is arranged in the cathode exhaust-gas flow path. The anode exhaust-gas flow path opens into the catalytic burner and/or into the cathode exhaust-gas flow path upstream of the catalytic burner. The combined, catalytically converted fuel cell exhaust-gas flow is passed into an expansion machine.

Abstract: A controller in a fuel cell system performs various operating parameter checks at a predefined schedule, including one or more of a stack current check; a stack voltage check; a cell voltage check; a purge cell check; an oxygen concentration check; a hydrogen concentration check; a stack temperature check; an ambient air temperature check; a fuel pressure check; and an airflow rate check; a hydrogen sensor heater check; a battery voltage check; a microcontroller self-check; and/or toggling a watchdog. The frequency of the checks are set relative to achieve an efficient control of the fuel cell system by selectively distributing the load on the microcontroller.

Abstract: Contamination of the ion-exchange membrane in an electrochemical fuel cell can significantly reduce the lifetime. One source of contamination is from sealant materials, particularly if the sealant is silicone and impregnated into the peripheral region of the membrane electrode assembly (MEA) and thus in close proximity to the ion-exchange membrane. Contamination may be reduced or eliminated by separating the electrochemical reaction and/or the ion-exchange membrane from the sealant material. In an embodiment, this is done by having the sealing region substantially free of active electrocatalyst particles (for example, selectively printing the catalyst to avoid the sealing region or poisoning catalyst in the sealing region). In another embodiment, a barrier film is interposed between the ion-exchange membrane and the sealant material impregnated into the MEA. In yet another embodiment, a barrier plug is impregnated into the fluid diffusion layer adjacent to the sealant material impregnated into the MEA.

Abstract: A fuel cell system includes a fuel cell stack with single fuel cells stacked together in a fuel cell housing and a detection system for fire or elevated temperatures. The detection system may include a monitoring system; a sensor unit that detects fire or elevated temperatures inside said fuel cell housing; and a voltage or current source.

Abstract: A fuel cell system having a fuel cell unit and a means for detecting hydrogen leaks in the fuel cell system. The fuel cell system comprises components which operate at an elevated temperature and are accommodated in a gas generation system box. The gas generation system box is connected to a suction line of a pump, which has a gas sensor arranged therein.

Abstract: A power converter may employ a planar transformer to minimize winding conduction loss, and the switching devices of the power converter may be aligned in lines parallel to an edge of the planar transformer to minimize the termination leakage inductance. The windings of the planar transformer may be thermally conductively coupled to one or more heat sinks carried by a circuit board which are with respective ones of the switching devices, to provide a cooling path for the planar transformer.

Abstract: A method and device for insulation monitoring of an electrically insulated DC network by measuring of the insulation resistance using galvanic isolation between a measuring resistor which is connected to ground, and a measuring pulse generator, and a measurement-data acquisition device, which eliminates some of the effect that noise in the DC network would otherwise have on the measurement.

Abstract: A method for locating a fluid leak in a fuel cell stack is disclosed. The method comprises pressurizing a first fluid stream passage with a tracer fluid, introducing a flow fluid to a second fluid stream passage, maintaining a substantially constant flow of the flow fluid through the second fluid stream passage toward an exit point of the fuel cell stack, inserting a probe, adapted to monitor for the presence of the tracer fluid in the flow fluid, into the exit point, moving the probe through the second fluid stream passage and monitoring for the presence of the tracer fluid in the flow fluid at various locations of the second fluid stream passage. An apparatus for locating a fluid leak in a fuel cell stack is also provided.

Abstract: An electric power generation system has a multiple jet ejector assembly for recirculating an exhaust stream. The system includes a fuel cell stack having a reactant stream inlet, a reactant stream outlet and at least one fuel cell. A pressurized reactant supply provides a reactant to the multiple jet ejector assembly. The multiple jet ejector assembly includes two motive flow inlets, one suction inlet, fluidly connected to the reactant stream outlet to receive a recirculated flow from the fuel cell stack, and one discharge outlet, fluidly connected to the reactant stream inlet to provide an inlet stream to the fuel cell stack. A pressure regulator is interposed between the pressurized reactant supply and the two motive flow inlets of the multiple jet ejector assembly. A first solenoid valve is interposed between the first motive flow inlet and the regulator. A second solenoid valve is interposed between the second motive flow inlet and the regulator.

Abstract: Apparatus and method for cooling and preventing the deterioration of the windings of an electric machine. The apparatus includes an electrically insulative spacer wedgingly disposed between adjacent windings.

Abstract: A disclosed method for coating a substrate with an ionomer, applies the ionomer as a component of a stable foam, then dries the applied foam layer. The substrate to be so coated, in particular embodiments, is an electrode substrate, with or without a catalyst layer applied thereon. In another embodiment, the substrate is an ion-exchange membrane. In yet more particular embodiments, the substrate is suitable for use in an electrochemical fuel cell. Also disclosed are products made by the disclosed methods, namely, ionomer-coated substrates, including ionomer-coated electrode substrates and electrodes. The foam layer may also comprise catalyst powder to form a catalyst layer. Membrane electrode assemblies, fuel cells, and fuel cell stacks that incorporate the substrates are also disclosed, as are motor vehicles, and stationary and portable electrical power-generating plants that incorporate the fuel cell stacks.

Abstract: A multilevel inverter control system having logic configured to substantially minimize and area between a target waveform and a step signal of a multilevel inverter.

Abstract: An efficient emulation of EEPROM employing flash memory employs a fixed location for an address pointer in flash memory and such that an erase operation is required only once every nth update where n is the number of bits at the fixed location, thus avoiding the need to erase the sector on every update and avoiding delays associated with linked lists for determining the address of the most up-to-date information. Use of bit shifting provides fast determination of the desired address.

Abstract: A method serves the purpose of introducing fuel and/or thermal energy into a gas stream flowing to a catalytic reactor. The gas stream flows in part through an exterior chamber and in part through an interior chamber, which is at least partially open in the flow direction and to which fuel is supplied. The partial streams are re-united after flowing through the two chambers and are fed to the catalytic reactor. In a starting phase of the still cold catalytic reactor, the fuel is burned in the interior chamber. During conventional normal operating modes of the warm catalytic reactor, the fuel is vaporized in the interior chamber. In a suitable device, the exterior chamber and the interior chamber are designed as two tube elements that are inserted into one another.

Abstract: A membrane exchange humidifier employs a water permeable membrane comprising a microporous polymer and a hydrophilic additive. In operation, the membrane preferably has favorable water transmission properties and resists transmission of reactant gas or other components. The membrane is suitable for use even when permeable in its dry condition to the wet or dry gases in the humidifier, and/or when the wet and dry gases are of different composition. By wetting the membrane, the presence of an amount of liquid water in the wet gas can reduce gas transmission through the membrane to an acceptable level. The humidifier is useful in fuel cell systems in which a reactant gas supply stream, such as the oxidant supply stream, is humidified primarily using water vapor from a fuel cell reactant exhaust stream. The humidifier is particularly suitable for use in conjunction with solid polymer fuel cell systems. The improved mechanical and welding properties of the membrane allow for a simpler humidifier configuration.

Abstract: A receptacle having an end cap, a pliable sidewall, and a fastener, for receiving and retaining a fuel cell stack in its stacked configuration during fabrication of a multi-stack fuel cell assembly, is shown and described. Methods of fabricating the assembly include stacking the fuel cell in the receptacle, compressing the fuel cell, and engaging the fastener to retain the stack in its stacked configuration and, or to retain the stack under at least partial compression.

Abstract: Insulation monitoring of an electrical network such as a DC network which is electrically insulated with respect to the ground of a device, includes at least two insulation monitoring devices that monitor different network sections, which can be isolated by one or more switches. Non-contacting switches are used to alternatingly connect and isolate respective measuring resistors of the monitoring devices to, and from, ground, as a result of which the insulation monitoring devices can not negatively affect each other's measurements.

Abstract: Fuel cells are disclosed that operate directly on fuel streams comprising tetramethyl orthocarbonate in which tetramethyl orthocarbonate is directly oxidized at the anode and, more particularly, to solid polymer fuel cells operating directly on liquid fuel streams comprising tetramethyl orthocarbonate. Also disclosed are methods relating thereto.

Abstract: Graft polymeric membranes and methods for making graft polymeric membranes have one or more trifluorovinyl aromatic monomers that are radiation graft polymerized to a polymeric base film. The membranes comprise a polymeric base film to which has been graft polymerized substituted ?,?,?-trifluorostyrene and/or ?,?,?-trifluorovinylnaphthylene monomers, which are activated towards graft polymerization. As ion-exchange membranes, the membranes are suitable for use in electrode apparatus, including membrane electrode assemblies in, for example, fuel cells. The membranes can also be crosslinked.

Abstract: A fuel cell system has at least one fuel cell and a fan for supplying air to the at least one fuel cell. Sound-absorbing means for absorbing sound in the air section of the fuel cell system are designed as broadband silencers.