Abstract: System and methods for estimating a capacity of a battery are presented. A measure of data skewness may be calculated from a battery system terminal voltage measurement. Inflection points in the data skewness of the terminal voltage measurement may align with transition points associated with a battery system. These transitions points may be associated with known SOCs determined from testing and/or characterization of the battery system. Using the detected transitions and associated SOCs and an indication of an accumulated charge provided to/from the battery between the transitions, an estimated capacity of the battery system may be determined.

Abstract: A fuel cell system is disclosed with 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 sensor for measuring at least one of an environmental condition affecting the fuel cell stack and a characteristic of the fuel cell stack, wherein the sensor generates a sensor signal representing the measurement of the sensor; and a processor for receiving the sensor signal, analyzing the sensor signal, and controlling a flow rate of a fluid flowing into the anode supply manifold based upon the analysis of the sensor signal.

Abstract: A method including shutting down an electrochemical fuel cell stack wherein anode pressure is controlled according to a stack discharge fuel consumption estimate.

Abstract: 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.

Abstract: A battery state estimator which combines an electrochemical solid-state concentration model with an empirical equivalent-circuit model. The battery state estimator uses a reduced-order physics-based electrochemical solid-state concentration model to calculate open circuit voltage of a battery cell, and uses the calculated open circuit voltage in an equivalent-circuit model to evaluate a diffusion voltage drop and other battery cell parameters. The battery state estimator is implemented in an online estimator framework using an extended Kalman filter, with a measured terminal voltage and measured current as inputs. A state of charge of the battery cell can be determined from the calculated open circuit voltage, and the state of charge along with the other parameters from the equivalent-circuit model are used to evaluate battery pack performance and to control battery pack charging and discharging.

Abstract: Adaptive estimation techniques to create a battery state estimator to estimate power capabilities of the battery pack in a vehicle. The estimator adaptively updates circuit model parameters used to calculate the voltage states of the ECM of a battery pack. The adaptive estimation techniques may also be used to calculate a solid-state diffusion voltage effects within the battery pack. The adaptive estimator is used to increase robustness of the calculation to sensor noise, modeling error, and battery pack degradation.

Abstract: Methods are disclosed for modeling changes in capacity and the state of charge vs. open circuit voltage (SOC-OCV) curve for a battery cell as it ages. During battery pack charging, voltage and current data are gathered for a battery cell. In one method, using multiple data points taken during the plug-in charge event, data optimization is used to determine values for two parameters which define a scaling and a shifting of the SOC-OCV curve from its original shape at the cell's beginning of life to its shape in the cell's current condition. In a second method, only initial and final voltages and current throughput data are needed to determine the values of the two parameters. With the scaling and shifting parameters calculated, the cell's updated capacity and updated SOC-OCV curve can be determined. The methods can also be applied to data taken during a discharge event.

Abstract: 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.

Abstract: Systems and methods for improvements in battery state of charge accuracy, charge termination consistency, capacity estimation, and energy delivery consistency. More specifically, embodiments herein detail systems and methods using an algorithm to calculate the change in state of charge for a given voltage change (dSOC/dV) at a given temperature in a region around the present voltage measurement or estimation and to set a signal indicating when the measurement should not be used due to potential error.

Abstract: A system and method for determining whether valves in a fuel cell system bleed manifold unit (BMU) are blocked with ice or have otherwise failed. The system opens a first bleed valve, closes a second bleed valve and opens an exhaust valve, and then reads a pressure signal to determine whether there is flow through a flow restriction to determine whether the first bleed valve or the exhaust valve is blocked. The system then closes the exhaust valve, leaves the first bleed valve open, and again reads the pressure signal to determine the pressure drop across the flow restriction, which will indicate whether the flow restriction the pressure sensor lines are blocked. The system then closes the first bleed valve and opens the second bleed valve to determine whether the pressure signal indicates a flow through the second bleed valve.

Abstract: A method for adaptively controlling a fuel delivery injector in a fuel cell system, including determining a feed-forward bias for the fuel delivery injector, determining an injector flow set-point for the fuel delivery injector, monitoring stack current, determining a transient pressure correction for the stack and correcting the injector flow set-point.

Abstract: A system and method for preventing low performing cells in a fuel cell stack. The method includes periodically providing a pulse of the cathode input airflow at low stack current densities, and comparing the current density output of each cell in response to the pulse. Those cells that do not have significant water accumulation will provide one voltage signature and those cells that do have a significant water accumulation will provide another voltage signature. If one or more of the cells exhibit the voltage signature for water accumulation, then the cathode inlet airflow pulses can be provided more often to prevent the cells from failing.

Abstract: A system and method for providing an anode exhaust gas bleed in a fuel cell system. The system provides a normal anode side bleed using first and second bleed valves if the first and second bleed valves are not blocked and the temperature of first and second split sub-stacks is greater than a predetermined temperature, provides a continuous anode side bleed using the bleed valves if the bleed valves are not blocked and the temperature of the sub-stacks is less than the predetermined temperature, provides a normal center anode bleed through the drain valve if the first or second bleed valve is blocked and the temperature of the sub-stacks is above the predetermined temperature and provides a continuous center anode side bleed through the drain valve if the first or second bleed valve is blocked and the temperature of the sub-stacks is below the predetermined temperature.

Abstract: A method for adaptively controlling a fuel delivery injector in a fuel cell system, including determining a feed-forward bias for the fuel delivery injector, determining an injector flow set-point for the fuel delivery injector, monitoring stack current, determining a transient pressure correction for the stack and correcting the injector flow set-point.

Abstract: A fuel cell system is disclosed with 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 sensor for measuring at least one of an environmental condition affecting the fuel cell stack and a characteristic of the fuel cell stack, wherein the sensor generates a sensor signal representing the measurement of the sensor; and a processor for receiving the sensor signal, analyzing the sensor signal, and controlling a flow rate of a fluid flowing into the anode supply manifold based upon the analysis of the sensor signal.

Abstract: A method including shutting down an electrochemical fuel cell stack wherein anode pressure is controlled according to a stack discharge fuel consumption estimate.

Abstract: A fuel cell system that determines the phase transition from water to gas through a bleed/drain valve in a water separation device. The fuel cell system includes a fuel cell stack having an anode side and a cathode side. An injector injects hydrogen gas into the anode side of the fuel cell stack. The water separation device receives an anode exhaust gas from the anode side of the fuel cell stack, where the water separation device includes a water holding reservoir. A controller controls the injector and the bleed/drain valve and determines when the bleed/drain valve transitions from draining water to bleeding the anode exhaust gas by comparing the flow rate through the water separation device and the flow rate through the injector.

Abstract: A method for monitoring the pressure in an anode sub-system of a fuel cell system during a pressurization stage at system start-up prior to an anode purge. The method includes providing hydrogen gas to the anode sub-system during the pressurization stage, typically from one or more injectors. The method determines how many moles of the hydrogen gas has been provided to the anode sub-system, and uses the number of moles to determine the pressure in the anode sub-system. The method uses the determined pressure to stop the pressurization stage when the determined pressure is about equal to the desired pressure.

Abstract: 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.

Abstract: 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.