Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A fuel cell system that includes a single enclosure for all of a fuel cell stack and other stack critical electronics and components, such as power distribution components, voltage monitoring and detecting components, electrical isolation components, etc. The single enclosure offers a number of advantages, such as reduced weight and reduced complexity for service and safety.

Abstract: 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.

Abstract: A transient load can be applied to a fuel cell stack to generate an AC voltage across and an AC current through the fuel cell stack. The AC voltage and AC current can be used to ascertain an impedance of the fuel cell stack. The ascertained impedance can be correlated to a state of hydration of the fuel cell stack thereby providing an independent determination of the state of hydration. The independently determined state of hydration can be used as a diagnostic tool to verify a different independent determination of the state of hydration and/or as an input for controlling operation of the fuel cell stack.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method for the sensorless drive control of an electric vehicle, especially an industrial truck, driven by a rotating field motor operated by a power converter, the power converter being supplied by an associated constant voltage source, includes calculating actual values of the flow chain of the rotating field motor and at least one other variable dependant on the actual values from a recorded stator voltage and at least n−1 measured phase flows, and regulating the stator flow of the rotating field drive, which is defined by the phase flows, based upon the actual values.