Abstract: In a fuel cell system having a gas generation system for providing hydrogen from a carbon- and hydrogen-containing medium for a fuel cell unit, means are provided for adjusting pressure in the gas generation system and/or mass flow through the fuel cell unit, upstream of the fuel cell unit. In a transition from a part-load range to a full-load range, the pressure can be at least briefly reduced, and in a transition from a full-load range to a part-load range, the pressure can be at least briefly increased.

Abstract: Methods and apparatus for supplying an oxidant stream, in particular air, to a cathode of a fuel cell, include an oxidant supply device and a return line to recirculate part of the oxidant discharged from the cathode into the oxidant supplied to the cathode. A throttle device is located in the return line, which is connected upstream of the oxidant supply device.

Abstract: &agr;,&bgr;,&bgr;-Trifluorostyrene and derivatives thereof synthesized in two steps from 1,1,1,2-tetrafluoroethylene. In the first step, 1,1,1,2-tetrafluoroethylene is reacted with a base, a metal salt such as zinc chloride and an optionally amine to form a trifluorovinyl metal complex. In the second step, the trifluorostyrene or derivative is obtained by reacting the trifluorovinyl metal complex with an aryl transfer agent such as, for example, an aryl triflate or an aryl halide, in the presence of a metal catalyst and optionally a coordinating ligand. Both steps may be carried out in one reactor.

Abstract: In a fuel cell system, and a method of operating a fuel cell system comprising a fuel cell unit and an air supply for providing a fuel for the fuel cell unit, a compressor having a variable internal compression ratio is provided for media delivery in the gas generation system.

Abstract: A vaporizer, a fuel cell system including the vaporizer, and a method of vaporizing fuel in a fuel cell system are disclosed. The fuel cell system includes a fuel reservoir (24) for storing a liquid fuel and a fuel cell (10) for consuming a fuel and generating electricity therefrom. A fuel vaporizer (28) is interposed between the fuel reservoir (24) and the fuel cell (10) for receiving liquid fuel and vaporizing it and delivering it ultimately to the fuel cell (10). The fuel vaporizer (28) includes a heat exchanger which includes a hot fluid inlet (65), a hot fluid outlet (67) and a core (50) interconnecting the inlet (65) and the outlet (68). The core (50) has alternating fuel flow structures (68) and hot fluid structures (69) with the fuel flow structures (68,69) having an inlet (56) and an outlet (58).

Abstract: Circuits and methods for use with an integrated circuit chip having internal back EMF estimation to control a permanent magnet synchronous motor includes an AC current feedback circuit, a scaling circuit, and a current regulator. Additionally, a speed regulator may be employed. In one embodiment, during operation at very low speed, the speed regulator is in an open loop control mode due to a back EMF detection limitation of the IC chip, and only the current regulator is active. A feedback current signal, together with a user-defined command current signal, serves the input of the current regulator, which controls the AC motor current and drives the motor speed from standstill. Once the motor speed reaches a certain level, the measured back EMF from the IC chip is sufficient to estimate the motor speed, which is compared with a user-defined command speed, and an error of the these two signals provides the input of a speed regulator.

Abstract: Integrated power conversion systems and methods for use in an electric vehicle having an electric motor, a primary high-voltage energy source, and an auxiliary energy source including a traction inverter module operable for converting a DC current generated by the high-voltage energy source into an AC current capable of powering the electric motor, and a DC/DC converter operable to step-down a voltage of the high-voltage energy source or step-up a voltage of the auxiliary energy source, wherein the traction inverter module and the DC/DC converter may share one or more common components, such as a common high-voltage DC bus capacitor, a common DC bus bar, and/or a common high-voltage transistor.

Abstract: A contacting device comprising a non-metallic, electrically conductive elastomeric composition for providing reliable, corrosion resistant electrical contacts to fuel cell components. Such a contacting device is particularly suitable for measuring voltages at carbon separator plates in a solid polymer electrolyte fuel cell stack.

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: In a method and apparatus for cutting expanded graphite sheet material, at least one cutting tool is urged against the sheet(s). The cutting tool has at least one ridge extending therefrom, that includes a substantially tapered cross-section having sloping sides and an edge surface. At least a portion of the sheet material is displaced as the ridge is urged against the sheet. A region of the sheet material in contact with the ridge is compressed so that the density of the region reaches or exceeds the breaking density of the sheet.

Abstract: A device for evaporating liquids includes a porous, thermally conductive evaporation body, which contains a catalyst material on one surface, while the evaporation body is gas-impermeable on the opposite surface. Liquid which is to be evaporated and, if appropriate an additional fuel, can be fed to the evaporation body. The heat of evaporation required is provided by an exothermic reaction of the liquid or with a gaseous oxidizing agent at the catalyst material.

Abstract: A device inserted between a grounded poly-phase external voltage source and a load providing low insertion loss for differential mode currents and high insertion loss for ground currents. The device receives voltages from the grounded poly-phase external voltage source over atone or more voltage lines. The voltages contain common mode voltages. A filter connected to each of the voltage lines reduces the ground current from the load. A summing block adds the voltages from each of the voltage lines to generate a total common mode voltage. A ground referenced controlled voltage source generates a cancellation voltage equal to the total common mode voltage in response to the generation of total common mode voltage. The total common mode voltage is injected into the filter and substantially reduces the common mode voltage on each voltage line thereby substantially reducing the ground currents associated with each common mode voltage on each voltage line.

Abstract: An electrical data bus system comprises at least one monitoring device for detecting leakage of a flammable gas within a fuel zone. Pursuant to the method, upon a flammable gas leak within the fuel zone being detected, the flow of electrical current in the fuel zone, via the data bus system or any device connected to the data bus system, is prevented.

Abstract: To carry out a heterogeneously catalysed reaction, such as for example the generation of hydrogen from hydrocarbons or alcohol, in particular methanol, in which a reaction mixture comprising hydrocarbon and water is fed onto a catalyst, a catalyst is proposed which is produced by compressing at least one catalyst powder into a highly compressed layer which forms a shaped body, it being possible to press the reaction mixture through the catalyst layer with a pressure drop.

Abstract: An assembly for cooling an electric motor, the assembly comprising a housing, a stator, a rotor, a winding, an end-winding integrally formed with the winding, and a jet impingement device operable for exposing the end-winding to a temperature controlled stream of fluid. A method for transferring heat between a stream of impinging fluid and the surface of an electric motor end-winding. An electric motor comprising a jet impingement cooling assembly.

Abstract: A method of detecting transfer leaks within a solid polymer electrolyte fuel cell stack comprising a plurality of fuel cell assemblies includes supplying reactants and inert gas to the fuel, oxidant and/or coolant manifolds of the stack, as appropriate, and measuring the voltage across at least one of the fuel cell assemblies. An apparatus for detecting transfer leaks within solid polymer electrolyte fuel cell stacks comprises a device for measuring the voltage across at least one of the fuel cell assemblies. Transfer leaks across the polymer electrolyte membrane, and across reactant-coolant bipolar plates, may be detected according to the present method and apparatus.

Abstract: A separator plate for use in a fuel cell stack has a fuel gas flow field adjacent one surface and an oxidant gas flow field adjacent the other surface. The fuel cells in the stack are proton exchange membrane fuel cells having undulate membrane electrode assemblies. The flowpaths of the flow fields comprise parallel flow channels that extend longitudinally and interconnected at their ends to the separator plates. The couplings for the oxidant gas flow channels are offset from those for the fuel flow channels. The interconnecting couplings may be formed by stamping, machining or molding the separator plate.

Abstract: A device and method of commutation control for an isolated boost converter provides a unique commutation logic to limit voltage spikes by utilizing switches on the secondary side to minimize a mismatch between current in the inductor and current in the leakage inductance of the transformer when commutation takes places. To minimize this mismatch, the current in the leakage inductance is preset at a certain level that approaches the current in the inductor prior to the commutation, thus significantly reducing the power rating for a clamp circuit and enabling use of a simple passive clamp circuit. In addition, through unique timing of the turn-on of the secondary switches, soft switching conditions are created that eliminate turn-on losses and the reverse recovery problems of free-wheeling diodes.

Abstract: A high frequency, low impedance network is integrated into the substrate level of a power module for the reduction of electromagnetic interference (“EMI”). In one embodiment, capacitance is electrically connected to at least one of the positive conducting layer in a substrate or the negative conducting layer in a substrate and a ground. Integrating a capacitive network of low stray inductance in a substrate of a power module allows relatively small, inexpensive capacitors to be used.

Abstract: A combined component consists of a heat exchanger and a reactor. The heat exchanger is designed in a plate form, and flow spaces for a first medium and a second medium are alternately defined between successive plates. The plates of the heat exchanger are configured as essentially annular. The heat exchanger has, substantially perpendicularly to the plates, a tubular outer wall and a tubular inner wall. The reactor is surrounded by the inner wall of the heat exchanger. The product of the reactor is conducted through supply orifices on the inner wall of the heat exchanger into the flow spaces for one of the two fluids in the heat exchanger.