Patents by Inventor Michael J. Kiefer

Michael J. Kiefer has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Selectively reacting to the minimum cell voltage drop rate in a fuel cell system
    Patent number: 9231263
    Abstract: A system and method that monitor the rate of a voltage drop of fuel cells in a fuel cell stack to determine whether the voltage drop is a result of cathode reactant starvation or anode reactant starvation. The method looks at a falling voltage of a fuel cell to determine whether the rate of the fall in voltage indicates that hydrogen starvation of the anode of the fuel cell is occurring. The method also looks at the actual voltage of the fuel cell that is falling to determine whether it is a below a predetermined minimum voltage threshold also indicating that hydrogen starvation of the anode of the fuel cell is occurring. If hydrogen starvation is occurring, the method performs power limiting of the fuel cell stack either based on the rate or the voltage level.
    Type: Grant
    Filed: January 21, 2013
    Date of Patent: January 5, 2016
    Assignee: GM Global Technology Operations LLC
    Inventors: Derek R. Lebzelter, Balasubramanian Lakshmanan, Sriram Ganapathy, Sanja Sljivar-Lovria, Bruce J. Clingerman, Michael J. Kiefer
  • SELECTIVELY REACTING TO THE MINIMUM CELL VOLTAGE DROP RATE IN A FUEL CELL SYSTEM
    Publication number: 20140205924
    Abstract: A system and method that monitor the rate of a voltage drop of fuel cells in a fuel cell stack to determine whether the voltage drop is a result of cathode reactant starvation or anode reactant starvation. The method looks at a falling voltage of a fuel cell to determine whether the rate of the fall in voltage indicates that hydrogen starvation of the anode of the fuel cell is occurring. The method also looks at the actual voltage of the fuel cell that is falling to determine whether it is a below a predetermined minimum voltage threshold also indicating that hydrogen starvation of the anode of the fuel cell is occurring. If hydrogen starvation is occurring, the method performs power limiting of the fuel cell stack either based on the rate or the voltage level.
    Type: Application
    Filed: January 21, 2013
    Publication date: July 24, 2014
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Derek R. Lebzelter, Balasubramanian Lakshmanan, Sriram Ganapathy, Sanja Sljivar-Lovria, Bruce J. Clingerman, Michael J. Kiefer