Gm Global Technolgoy Operations, Inc.

Peter Willimowski

Oliver Maier

Volker Formanski

Marc Becker

Robert Schafer

Sebastian Lienkamp

Peter Kilian

Thomas Herbig

Bernd Peter Elgas

Ulrich Dumke

Steven G Goebel

George R Woody

Manish Sinha

David A Arthur

John C Fagley

Jochen Schaffnit

Rolf Isermann

Thomas Weispfenning

Sascha Schaefer

Bernhard Baaser

Martin Fasse

Andreas Voigt

Jochen Lenz

Mirko Schwan

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

A thermal sub-system for a fuel cell system that employs an algorithm using feed-forward control. The algorithm calculates a Reynolds number based on the velocity of the cooling fluid, a diameter of a coolant loop pipe and a kinematic viscosity (temperature) of a cooling fluid. The algorithm also uses a pressure loss number based on the Reynolds number and a position of a by-pass valve. The algorithm also defines a pressure loss value based on the pressure loss number, the density of the cooling fluid and the velocity of the cooling fluid. The algorithm then calculates a delivery head value based on the pressure loss value, the fluid density and a gravitational acceleration. The algorithm then uses the delivery head value and a predetermined set-point value of the volume flow to determine a desired pump speed based on the current operating parameters of the system.

Feedforward control of the volume flow in a hydraulic system

Diagnostic system for unbalanced motor shafts for high speed compressor

A power request controller that prevents a power request signal to a fuel cell stack controller from providing more compressor air and hydrogen gas than is necessary to meet the current power demands of the vehicle. The stack controller generates a signal of the available current from the fuel cell stack. This signal and the measured current actually being drawn from the stack are received by a proportional-integral (P-I) controller in the power request controller. If the available stack current is significantly greater than the stack current being used, the P-I controller will provide an output signal that reduces the power request signal to the stack controller so that the current produced by the stack and the current being drawn from the stack are substantially the same. A transient detector turns off the P-I controller so that it does not reduce the power request signal during an up-power transient.

Fuel cell power request control strategy

A fuel cell assembly having a flow distribution subassembly that comprises four sets of flow channels, the first set facing an anode for distribution of a fuel reactant to said anode, the second set facing a cathode for distribution of an oxidant to said cathode, the third set in flow communication with said second set and in heat transfer relation with at least one of said anode and said cathode, and the fourth set receiving a coolant different from said oxidant.

Fuel cell design with an integrated heat exchanger and gas humidification unit

A technique for determining the relative humidity of the cathode input airflow to a fuel cell stack that eliminates the need for a dew-point sensor. The cathode input airflow is humidified by a water vapor transfer unit that uses water in the cathode exhaust gas. The technique employs an algorithm that determines the flow of water into the cathode inlet of the stack. In one embodiment, the algorithm determines the volume flow of water through the water vapor transfer unit using the Arrhenius equation, and then converts the water volume flow to a water mole flow. The algorithm then uses the water mole flow through the water vapor transfer unit and the water mole flow of ambient air to determine the water mole flow into the cathode inlet. The algorithm then uses the water mole flow into the cathode inlet to determine the relative humidity of the cathode airflow.

Sensorless relative humidity control in a fuel cell application

A gas control and operation method of a fuel cell system for improved water and gas distribution is disclosed. The present invention provides for a mechanization of a fuel cell system that allows control of the anode reactant and anode effluent through the anode portions of the fuel cell system to improve water and gas distribution on the anode side of the fuel cells that increases the voltage stability of the fuel cells.

Gas control and operation method of a fuel cell system for water and gas distribution

A device and method to predict and regulate nitrogen concentration in a flow shifting system. In one aspect of the system, a bleed valve fluidly coupled to multiple fuel cell stacks is used to reduce the presence of nitrogen in an anode flowpath. One or more sensors can be used to measure voltage within one or both of the fuel cell stacks. By assessing fuel cell voltage changes within the anode flowpath and equating such changes with nitrogen fraction buildup, the system can manipulate the bleed valve at appropriate times to improve system operability. In one form of equating the sensed voltage changes with the nitrogen fraction buildup, a predictive algorithm can be used by a logic device in a controller to compare the sensed voltage so that the controller instructs the bleed valve when to open and close. In a variation, the controller can compare the sensed voltages against stored data rather than rely on a formula or related algorithm.

Control of nitrogen fraction in a flow shifting fuel cell system

A strategy of controlling a state of hydration of a fuel cell(s) and actively managing operation of the fuel cell(s) to achieve a desired state of hydration. The control strategy monitors the state of hydration and a rate of change of the state of hydration which are used to control the operation of the fuel cell(s). A supervisory control strategy is implemented that alters the operating parameters of the fuel cell(s) based upon the state of hydration, the rate of change of the state of hydration, and a desired operational range for the state of hydration.

Management via dynamic water holdup estimator in a fuel cell

A technique for controlling the relative humidity of a cathode airflow to a fuel cell stack that includes compensating for valve non-linearities. The cathode input air flows through a water vapor transfer unit where it is humidified. The humidified cathode exhaust from the fuel cell stack is output to the water vapor transfer unit to provide the water vapor for humidifying the cathode input airflow. A first control valve controls the flow of the cathode exhaust through the water vapor transfer unit and a second control valve controls the flow of the cathode exhaust that by-passes the water vapor transfer unit to control both the relative humidity of the cathode input airflow and the pressure within the stack. By compensating for the non-linearity, the first and second valves control the relative humidity of the cathode airflow without changing the cathode output resistance.

Non-linear cathode inlet/outlet humidity control

A control algorithm for a by-pass valve in a thermal sub-system of a fuel cell system, where the by-pass valve includes a wax element that is heated by a heating element. A stack power loss is applied to a PDT1 controller that associates a PDT dynamic function to the loss. The difference between the desired temperature of the stack and the actual temperature of the stack is applied to a PI controller that provides an error value of the difference. The actual temperature of the stack is applied to a look-up table that provides a value based on how close the actual temperature is to the opening temperature of the wax element. The values from the PDT1 controller, the PI controller and the look-up table are added to provide an output signal to control the current applied to the heater element, and thus, the heat applied to the wax element.

Advanced control for an electrical heatable wax thermostat in the thermal coolant loop of fuel cell systems

A system and method for controlling a bleed valve and a compressor in a fuel cell system during an anode exhaust gas bleed so as to maintain the concentration of hydrogen within a mixed cathode exhaust gas and anode gas below a predetermined percentage. The system uses a valve orifice model to calculate the flow rate of the anode exhaust gas through the bleed valve to identify how much airflow from the compressor is required to dilute the hydrogen in the anode gas to be below the predetermined percentage. The system also uses sensor inaccuracies and production tolerances in the valve orifice model to ensure that the concentration of hydrogen in the mixed anode and cathode exhaust gas is below the determined percentage.

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Darmstadt, Germany

Peter Willimowski