| Patent application number | Description | Published |
|---|
| 20080236930 | SOFT START FUEL CELL CONTROL STRATEGY - A method of operating an electrochemical conversion assembly is provided. According to the method, an assembly warm-up operation is executed by increasing the temperature T | 10-02-2008 |
| 20080312849 | Anode Bleed Control Strategy for Improved Water Management and Hydrogen Utilization - A control strategy for bleeding an anode side of fuel cell stack in a fuel cell system that improves water management and addresses durability and performance concerns. The method includes determining when to begin the anode bleed, typically by estimating or measuring the amount of nitrogen in the anode side of the stack. The method also includes determining when to end the anode bleed based on the volume of gas that has been bled. The method determines the mole flow rate of the anode gas flowing through a bleed valve, integrates the mole flow rate to get the number of moles of the gas that have passed through the bleed valve, determines a desired amount of moles to be bled, and ends the bleed when the actual number of moles of the gas equals the desired number of moles of the gas. | 12-18-2008 |
| 20090081489 | ON-LINE SYSTEM IDENTIFICATION AND CONTROL OF FUEL CELL HUMIDIFICATION VIA HFR MEASUREMENTS - A fuel cell system is provided, including an HFR measurement device in electrical communication with a fuel cell stack. The HFR measurement is used online to measure an HFR of the fuel cell stack suitable for calculation of a d(HFR)/d(RH) ratio. A humidity regulator is provided in fluid communication with the fuel cell stack. A controller periodically changes stack operating conditions to perturb an RH of the fuel cell stack, process the HFR response, and compute the d(HFR)/d(RH) ratio. A method for online identification and control of the fuel cell stack humidification is also provided. The d(HFR)/d(RH) ratio is an auxiliary measurement of membrane hydration which is used as a feedback for hydration control. | 03-26-2009 |
| 20090197126 | Adaptive Gain Scheduled Control for Current Limitation Based on Voltage Performance of a Fuel Cell System - 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. | 08-06-2009 |
| 20100028728 | HUMIDIFICATION CONTROL DURING SHUTDOWN OF A FUEL CELL SYSTEM - A process for controlling the length of a purge and the purge rate of a fuel cell stack at system shut-down so as to provide the desired amount of stack humidity. The membrane humidification is measured at system shut-down by a high frequency resistance sensor that detects membrane humidification and provides the measurement to a controller. The controller controls the compressor that provides cathode input air to the fuel cell stack so that the time of the purge and the flow rate of the purge provide a desired membrane humidity for the next start-up. | 02-04-2010 |
| 20100190075 | SYSTEM AND METHOD FOR OBSERVING ANODE FLUID COMPOSITION DURING FUEL CELL START-UP - A fuel cell system including a fuel cell stack having a plurality of fuel cells, the fuel cell stack including an anode supply manifold and an anode exhaust manifold, a first valve in fluid communication with at least one of the anode supply manifold and the anode exhaust manifold, wherein the first valve includes an inlet for receiving a fluid flow and an outlet for exhausting a fluid, a sensor for measuring at least a fluid pressure at the inlet and the outlet of the first valve, wherein the sensor generates a sensor signal representing the pressure measurement, and a processor for receiving the sensor signal, analyzing the sensor signal, and determining a composition of a fluid in the fuel cell system based upon the analysis of the sensor signal. | 07-29-2010 |
| 20110113857 | ONLINE ESTIMATION OF CATHODE INLET AND OUTLET RH FROM STACK AVERAGE HFR - A method for estimating cathode inlet and cathode outlet relative humidity (RH) of a fuel cell stack. The method uses a model to estimate the high frequency resistance (HFR) of the fuel cell stack based on water specie balance, and also measures stack HFR. The HFR values from the estimated HFR and the measured HFR are compared, and an error between the HFR values is determined. An online regression algorithm is then utilized to minimize the error and the solution of the regression is the RH profile in the stack including the cathode inlet and outlet relative humidities. | 05-19-2011 |
| 20110189569 | AUTO-LEARNING OF BASE STACK RESISTANCE FOR HFR BASED RH CONTROL - A method for determining membrane humidification by determining the membrane protonic resistance of a fuel cell stack at humidified conditions, and normalizing the base resistance of the fuel cell stack against the base resistance of a reference fuel cell stack. | 08-04-2011 |
| 20110189573 | ONLINE ANODE PRESSURE BIAS TO MAXIMIZE BLEED VELOCITY WHILE MEETING EMISSION CONSTRAINT - A method that employs a model based approach to determine a maximum anode pressure set-point based on existing airflow in the exhaust gas line. This approach maximizes anode flow channel velocity during bleed events while meeting the hydrogen emission constraint, which in turn increases the amount of water purged from the anode flow channels to increase stack stability. | 08-04-2011 |
