Gm Global Technolgoy Operations, Inc.

David R Savage

John P Salvador

Balasubramanian Lakshmanan

David A Arthur

Sriram Ganapathy

Manish Sinha

Derek R Lebzelter

Seth E Lerner

Akbar Chowdhury

Jon R Sienkowski

Jun Cai

Jameson R Forte

Jaehak Jung

Joe C Machuca

Bernd Krause

Daniel T Folmsbee

Tayoung Choi

Frank Leo

Trevor T Grover

James K Leary

Pamela M Vecasey

William S Marley

Eric K Jensen

A method for reconditioning a fuel cell stack. The method includes periodically increasing the relative humidity level of the cathode input airflow to the stack to saturate the cell membrane electrode assemblies to be greater than the relative humidity levels during normal stack operating conditions. The method also includes providing hydrogen to the anode side of the fuel cell stack at system shut down while the membrane electrode assemblies are saturated without stack loads being applied so that the hydrogen crosses the cell membranes to the cathode side and reacts with oxygen to reduce stack contaminants.

In-situ fuel cell stack reconditioning

A system and method for detecting a low performing cell in a fuel cell stack using measured cell voltages. The method includes determining that the fuel cell stack is running, the stack coolant temperature is above a certain temperature and the stack current density is within a relatively low power range. The method further includes calculating the average cell voltage, and determining whether the difference between the average cell voltage and the minimum cell voltage is greater than a predetermined threshold. If the difference between the average cell voltage and the minimum cell voltage is greater than the predetermined threshold and the minimum cell voltage is less than another predetermined threshold, then the method increments a low performing cell timer. A ratio of the low performing cell timer and a system run timer is calculated to identify a low performing cell.

Method to improve reliability of a fuel cell system using low performance cell detection at low power operation

A system and method for correcting a large fuel cell voltage spread for a split sub-stack fuel cell system. The system includes a hydrogen source that provides hydrogen to each split sub-stack and bleed valves for bleeding the anode side of the sub-stacks. The system also includes a voltage measuring device for measuring the voltage of each cell in the split sub-stacks. The system provides two levels for correcting a large stack voltage spread problem. The first level includes sending fresh hydrogen to the weak sub-stack well before a normal reactive bleed would occur, and the second level includes sending fresh hydrogen to the weak sub-stack and opening the bleed valve of the other sub-stack when the cell voltage spread is close to stack failure.

Anode reactive bleed and injector shift control strategy

A system and method for limiting the output current of a fuel cell stack as the stack degrades overtime. A look-up table identifies a predetermined voltage set-point for stack current density. A first comparator provides a voltage difference signal between the set-point and the stack voltage. The voltage difference signal is provided to a controller, such as a proportional-integral controller, that provides a current limiting signal. The current limiting signal and a current request signal are provided to a second comparator that selects which signal will be used to limit the maximum output current of the stack. A polarization curve estimator estimates parameters of the stack that will change over the life of the stack. The parameters are provided to a gain scheduler that provides gains to the controller that are based on where in the life of the stack it is currently operating.

Adaptive gain scheduled control for current limitation based on voltage performance of a fuel cell system

A parallel dual stack fuel cell system having anode recirculation includes a first fuel cell stack and a second fuel cell stack. Each of the first and second fuel cell stacks includes a gas outlet line connected to an anode outlet unit. The anode outlet unit functions to release wet H/Ngaseous mixture from the system. A second water separator is provided between the anode outlet unit and gas inlet lines to the first and second fuel cell stacks to increase removal of water droplets prior to a recirculation pump.

Anode recirculation for a parallel dual stack fuel cell system

A fuel cell system including a compact, low-pressure-drop, high efficiency water-separator for separating liquid water from water-laden streams of the system. A cyclonic separator includes a sump for collecting the water, a drain for removing the water from the sump and directing it to a reservoir, a shutoff valve associated with the drain for controlling flow through from the drain, and a water level switch that controls the opening/closing of the valve. The switch triggers closing of the valve before the sump is emptied to provide a water seal that prevents escape of gas through the drain.

Fuel cell system having a compact water separator

Growing community of inventors

Rochester, NY, United States of America

David R Savage