Gm Global Technolgoy Operations, Inc.

Bernd Peter Elgas

Oliver Maier

Stephen W Raiser

Peter Willimowski

Ulrich Dumke

Jurgen Thyroff

Thomas P O'Meara

Dirk M Wexel

Richard Michael Breese

Stanley K Fujii

A diagnostic system for determining whether a rotor shaft of a compressor is unbalanced. The compressor includes a displacement sensor that measures the displacement of the rotor shaft as it is rotating. The sensor dynamic frequency signal is sent to a bandpass filter that filters out an eigen-frequency frequency that is a function of shaft elasticity and rotor dynamics. The filtered frequency signal is then rectified by a rectifier to make the filtered frequency signal positive. The rectified signal is then passed through a low pass filter that converts the rectified signal to a DC signal. The DC signal is then sent to a controller that determines if the amplitude of the signal is above a predetermined threshold, which indicates a problem with the balance of the compressor.

Fuel cell system including diagnostic technique for unbalanced compressor

Diagnostic system for unbalanced motor shafts for high speed compressor

One embodiment of the invention includes a product comprising a fuel cell stack comprising at least one coolant header, and at least one heater at least partially disposed in the at least one coolant header.

Fuel cell heating

A stator assembly for use in a fluid-cooled motor is disclosed, wherein a cooling jacket is disposed around a main body of the stator, the cooling jacket including at least one conduit adapted to receive a coolant therein, thereby minimizing a complexity and a cost of manufacture of the stator assembly, and maximizing a cooling capability of the stator assembly.

Stator assembly for use in a fluid-cooled motor and method of making the same

Methods and apparatus are provided for monitoring a coolant conductivity of a fuel cell supplying power via positive and negative buses. The method includes measuring a first voltage of the positive bus, measuring a second voltage of the negative bus, applying a resistance between the positive bus and a reference potential, measuring a third voltage of the positive bus after a period of applying the resistance, and determining an isolation resistance based on the measured voltages. The isolation resistance is a function of the coolant conductivity.

Method and apparatus for monitoring fuel cells

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Hilbersheim, Germany

Bernd Peter Elgas