Gm Global Technolgoy Operations, Inc.

John Wheat

Jason R Kolodziej

Clark G Hochgraf

Scott Dewey

Victor W Logan

Michael D Cartwright

Ralf Senner

David B Ouwerkerk

Daryl Chapman

Dennis Brown

A fuel cell system that includes a fuel cell stack providing high voltage power. A tap is electrically coupled to the positive end of the stack to provide a positive voltage output terminal of the fuel cell stack, and a tap is electrically coupled to the negative end of the stack to provide a negative output terminal of the fuel cell stack. A low voltage tap is electrically coupled to one or more intermediate bipolar plates of the stack to provide low voltage power. Several intermediate taps can be electrically coupled to the bipolar plates, where a center intermediate tap is designated a reference potential tap. A switching network switches the several voltage potentials to provide an AC signal.

Low voltage power tap on high voltage stack

A fuel cell system wherein a plurality of fuel cells are arranged in a series of stages, the number of fuel cells decreasing in number in each stage from anode gas inlet to the anode gas outlet. The system allows for parallel flow to all of the cells in a given stage and series flow between the various stages. A similar configuration is present on a cathode side of the system. However, the direction of flow is reversed, providing a greater number of cells in the stage nearest the cathode outlet and a fewer number of cells in the stage near the cathode gas inlet. The invention further provides for the various stages to be configured such that the direction of flow of the anode gas of a given stage is generally opposite the direction of flow of the cathode gas of a given stage.

Fuel cell operating method with improved hydrogen and oxygen utilization

A fuel cell stack antifreeze system that purges a plurality of fuel cell stacks connected in parallel includes a compressor that supplies pressurized cathode gas to each of the plurality of fuel cell stacks. A controller deactivates a first group of one or more of the plurality of fuel cell stacks and maintains operation of a second group of one or more of the plurality of fuel cell stacks. The second group powers the compressor and the compressor purges excess fluid from the first group using the pressurized cathode gas.

Parallel stack antifreeze system

A fuel cell system includes fuel cell stacks electrically connected in parallel and supplying a gross current to a load. A controller determines the gross load current, and produces a desired current through the load by adjusting, based on the gross load current, at least one parameter affecting at least one of the inputs to and outputs from the system. This system allows a stack design and its voltage output to be kept constant while stacks are added for increased power.

Current control for parallel fuel cell stacks

Pressure control in a fuel cell is achieved by using an H-infinity controller coupled in a feedback loop between a reactant feed gas valve and a pressure sensor on gas flows to the membrane electrode assembly of the fuel cell. To maintain pressure balance across the membrane, the pressure of the oxidant reactant is used to regulate fuel reactant flow. An integrator windup compensator manages integral windup in the H-infinity control scheme. Control weight, sensor noise weight, and performance weight matrices are incorporated into the H-infinity control model. Respective to PID control, the H-infinity model provides superior performance in the presence of high frequency feedback noise enabling use of low cost control components in the fuel cell and a minimum of EMI shielding.

H-infinity control with integrator compensation for anode pressure control in a fuel cell stack

A system for detecting an isolation fault in a multi-stack fuel cell system. The system determines the percentage of the voltage from each stack in the multi-stack that contributes to the voltage at a positive terminal and a negative terminal of the stack when a no-fault condition exists. The system then uses those percentages and the actual measured stack voltages to determine if a fault condition exists. The actual voltage measurement at the positive terminal is compared to the calculated voltage contribution from each stack at the positive terminal for the no-fault condition. Also, the actual voltage measurement at the negative terminal is compared to the calculated voltage contribution from each, stack at the negative terminal for the no-fault condition. If there is a significant enough different between the calculated voltage for a no-fault condition and the calculated percentage of the actual voltage measurements, than a fault condition exists.

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Rochester, NY, United States of America

John Wheat