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 |
20110200895 | METHOD TO AUTOMATICALLY ENABLE/DISABLE STACK RECONDITIONING PROCEDURE BASED ON FUEL CELL STACK PARAMETER ESTIMATION - A system and method for determining when to trigger reconditioning of a fuel cell stack and when to disable the reconditioning of the fuel cell stack. In one embodiment, the stack reconditioning is triggered when a maximum stack power estimation falls below a first predetermined power threshold. The reconditioning of the stack can be disabled so it is not performed when the trigger occurs if the reconditioning process does not raise the maximum power estimation above a second predetermined power threshold or the time from one reconditioning trigger to a next reconditioning trigger is less than a predetermined time threshold, or both. | 08-18-2011 |
20110223505 | ADAPTIVE METHOD FOR CONVERSION OF EXTERNAL POWER REQUEST TO CURRENT SETPOINT TO A FUEL CELL SYSTEM BASED ON STACK PERFORMANCE - A system and method for converting a fuel cell stack power request signal to a stack current set-point that considers stack performance parameters. The method includes obtaining a power-current relationship curve of the fuel cell stack to provide stack parameters including exchange current density and mass transfer coefficient. The method then calculates a slope for the stack using the parameters from the power-current relationship curve estimation that includes calculating a cell voltage at two predetermined stack current densities. The method then calculates a change in current in response to the power request signal, the stack voltage, the stack current and the calculated slope, and uses the change in current to update the current set-point for the stack. | 09-15-2011 |
20110262822 | CONTROLS GIVING -25.degree. C FREEZE START CAPABILITY TO A FUEL CELL SYSTEM - A method for shutting down a fuel cell system including operating a fuel cell stack. the method includes providing an increased cathode air flow so as to dry fuel cell membranes in the stack until a first desired level of high frequency resistance is achieved, rehydrating the cell membranes of the stack until a second desired level of high frequency resistance is achieved, and operating the stack with a decreased cathode input relative humidity until a third desired level of high frequency resistance is achieved. | 10-27-2011 |
20130252116 | Model Based Approach For In-Situ WVTD Degradation Detection In Fuel Cell Vehicles - A method of estimating water vapor transfer unit degradation without having to remove the unit from a fuel cell system to which it cooperates, and a device performing the same. The method includes using a combination of a backward-looking model and a forward-looking model. The first of these models is used to evaluate changes in water vapor transfer effectiveness in the unit, while the second is for determining the water transfer rate of the unit. Together, the models provide a more accurate way to estimate and control relative humidity for both stack inlet and outlet flowpaths, as well as provide an indication of when service or replacement of the water vapor transfer unit may be warranted. | 09-26-2013 |
20140033801 | DIAGNOSING INJECTOR FAILURE VIA STACK VOLTAGE RESPONSE ANALYSIS - A system and method for determining whether an anode injector that injects hydrogen gas into an anode side of a fuel cell stack has failed. The method includes monitoring a voltage of the fuel cell stack and performing spectral analysis of the stack voltage to identify amplitude peaks in the stack voltage. The method further includes determining whether the spectral analysis of the stack voltage has identified an amplitude peak at a location where an amplitude peak should occur if the injector is operating properly. If no amplitude peak is identified at that location, then the method determines that the injector is not operating properly. If an amplitude peak is identified at that location, then the method compares the amplitude peak to the desired amplitude peak to identify if it is within a threshold to determine if the injector is operating properly. | 02-06-2014 |
20140120434 | METHOD FOR DETERMINING MEMBRANE PROTONIC RESISTANCE OF A FUEL CELL STACK - 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. | 05-01-2014 |
20140162171 | ANODE LEAK LOCATION DETECTION - A system and method for quantifying an anode leak location in a fuel cell system. The system and method include determining there is a leak in an anode sub-system of a fuel cell stack and estimating a first effective leak area using a first leak flow value and first operating parameters. The system and method also include increasing airflow to a cathode side of the fuel cell stack and estimating a second leak effective area using a second leak flow value and second operating parameters. The system and method further include comparing the first leak effective area to the second leak effective area and determining an anode outflow leak location based on the comparison between the first and second leak effective areas. | 06-12-2014 |
20140199605 | Transient Inlet Relative Humidity Estimation Via Adaptive Cathode Humidification Unit Model And High Frequency Resistance - An apparatus and method to determine the relative humidity of a fuel cell system. A controller is cooperative with a first device and a second device to receive a valve signal and a high frequency resistance value. The controller controls the relative humidity of a fuel cell stack based on the estimation of the relative humidity of the fuel cell stack based on one or more algorithms. The controller modifies the relative humidity of the fuel cell stack through changes in the position of a valve based on at least one of the valve signal and the high frequency resistance value. In one form, the relative humidity of the fuel cell system is determined without the need of a humidity sensor. | 07-17-2014 |
20140335432 | SYSTEMS AND METHODS FOR ESTIMATING FUEL CELL STATES - Apparatus, methods, and systems for estimating hydrogen concentration and/or pressure in an anode compartment of a fuel cell stack in a fuel cell vehicle. In some implementations, the estimates are based on a correlation between a transient dip in voltage in response to an anode to cathode bleed event and a concentration of hydrogen in the anode compartment of a fuel cell stack. Some implementations may comprise initiating a bleed event, sensing a transient dip in voltage in response to the bleed event, and using the correlation to calculate an estimate of a concentration and/or pressure of the gas in the anode compartment. The sensitivity of the correlation and hence the accuracy of estimation may change with the power level and may be accounted for in the correlation. | 11-13-2014 |