Abstract: An intermediate circuit for controlling the connection of a fuel cell stack to a load bus includes three switching elements arranged in a pi configuration. At least one such switching element is provided for short circuiting either or both of the fuel cell stack and the load bus, while a further switching element controllably interrupts the line connection between the fuel cell stack and the load bus. The respective switches are driven according to a control method that accommodates start-up operation, switch-off operation, emergency shut down, and a self diagnostic mode.

Abstract: An intermediate circuit for controlling the connection of a fuel cell stack to a load bus includes three switching elements arranged in a pi configuration. At least one such switching element is provided for short circuiting either or both of the fuel cell stack and the load bus, while a further switching element controllably interrupts the line connection between the fuel cell stack and the load bus. The respective switches are driven according to a control method that accommodates start-up operation, switch-off operation, emergency shut down, and a self diagnostic mode.

Abstract: The circuit configuration according to the invention comprises an electrical signal line loop, several partial systems connected thereto, which evaluate the state of the signal line loop, wherein a first selectable switching means is looped in between a first end of the signal line loop and a first voltage connection and a second selectable switching means is looped in between a second end of the signal line loop and a second voltage connection, and a selection unit for selecting the first and second switching means. Use, e.g. in a fuel cell system.

Abstract: A fuel cell based system for the generation of electrical energy employs a drive unit that includes at least two electric motors sharing a common rotor which is mechanically coupled to drive a compressor to provide oxidant and/or fuel to a fuel cell. An electrical storage device such as a battery produces a voltage in at least a low voltage one of the electric motors to startup the system, and the fuel cell supplies a voltage to a high voltage one of the electric motors to drive the compressor, one or more loads such as a traction motor, and/or recharge the electrical storage device during standard operation.

Abstract: A fuel cell system is provided that comprises a fuel cell for powering an electrical load, an oxidant supply device for supplying oxidant to the fuel cell, an energy storage device for providing at least temporary electrical power to drive the oxidant supply device and to the electrical load, and a control device which, in response to an increased power demand from the electrical load, directs the energy storage device to provide electrical power to the oxidant supply device, and then, when an increase in fuel cell power output has been detected, directs the energy storage device to provide electrical power to the electrical load. Methods for operating the fuel cell system are also provided.

Abstract: The circuit configuration according to the invention comprises an electrical signal line loop, several partial systems connected thereto, which evaluate the state of the signal line loop, wherein a first selectable switching means is looped in between a first end of the signal line loop and a first voltage connection and a second selectable switching means is looped in between a second end of the signal line loop and a second voltage connection, and a selection unit for selecting the first and second switching means. Use, e.g. in a fuel cell system.

Abstract: Regulation of energy supplied to an electric motor from an energy supply system including a fuel cell and an energy storage buffer such as a battery, improves the dynamic response of the motor by adding current from the energy storage buffer to the current from the fuel cell during acceleration.

Abstract: In a device for generating electrical power with the fuel cell in a vehicle, a temporary power storage supplies power for a battery start, is charged when the fuel cell is operating, outputs power to connected loads of the fuel cell power system when there is an increased power demand, and absorbs power during braking.

Abstract: A fuel cell based system for the generation of electrical energy employs a drive unit that includes at least two electric motors sharing a common rotor which is mechanically coupled to drive a compressor to provide oxidant and/or fuel to a fuel cell. An electrical storage device such as a battery produces a voltage in at least a low voltage one of the electric motors to startup the system, and the fuel cell supplies a voltage to a high voltage one of the electric motors to drive the compressor, one or more loads such as a traction motor, and/or recharge the electrical storage device during standard operation.

Abstract: Regulation of energy supplied to an electric motor from an energy supply system comprising a fuel cell and an energy storage buffer such as a battery, improves the dynamic response of the motor by adding current from the energy storage buffer to the current from the fuel cell during acceleration.

Abstract: An apparatus for generating and distributing electrical power in a vehicle which has at least one electric drive motor connected via a converter to a fuel cell unit, with the fuel cell unit being connected to at least one first, one second and one third voltage network, and with each voltage network having at least one associated electrical load and/or at least one associated energy store. The first voltage network is formed by the fuel cell voltage network and is connected via a first bidirectional DC/DC converter to the second voltage network and the first bidirectional DC/DC converter provides DC isolation between the first voltage network and the second voltage network. The second voltage network is connected via a second bidirectional converter to the third voltage network.

Abstract: A fuel cell system comprises a plurality of fuel cells arranged in a stack between two end plates. An electrical load is connected to the fuel cell stack via a load circuit, and a diode is arranged between the fuel cell stack and the electrical load in the load circuit. According to the invention, the diode is arranged directly on or in one of the end plates. Moreover, a cooling device, which is in thermal contact with the diode and dissipates the power loss from the diode, is provided in the region of the diode.

Abstract: A method and apparatus are provided for operating a fuel cell system. The method and apparatus can provide electrical power to a motor vehicle, the motor vehicle comprising a fuel cell, an electrical propulsion unit that is powered at least partially by the fuel cell, and a compressor to provide oxidant for the fuel cell. A target power demand may be determined based on an accelerator pedal demand. The power difference between the target power demand and the instantaneous power that is available from the fuel cell is compensated by power originating from an electrical energy storage device. Immediately after an increase in accelerator pedal demand, the electrical energy storage device first provides electrical power to drive the oxidant compressor, until a certain increase in the power available from the fuel cell has been detected. Once such an increase has been detected, the electrical energy storage device provides power to the electrical propulsion unit, such as a traction motor.

Abstract: An apparatus for generating and distributing electrical power in a vehicle which has at least one electric drive motor connected via a converter to a fuel cell unit, with the fuel cell unit being connected to at least one first, one second and one third voltage network, and with each voltage network having at least one associated electrical load and/or at least one associated energy store. The first voltage network is formed by the fuel cell voltage network and is connected via a first bidirectional DC/DC converter to the second voltage network and the first bidirectional DC/DC converter provides DC isolation between the first voltage network and the second voltage network. The second voltage network is connected via a second bidirectional converter to the third voltage network.

Abstract: A fuel cell system comprises a plurality of fuel cells arranged in a stack between two end plates. An electrical load is connected to the fuel cell stack via a load circuit, and a diode is arranged between the fuel cell stack and the electrical load in the load circuit. According to the invention, the diode is arranged directly on or in one of the end plates. Moreover, a cooling device, which is in thermal contact with the diode and dissipates the power loss from the diode, is provided in the region of the diode.