Abstract: System and methods for setting pressure limits for an air supply of a fuel cell (“FC”) system are presented. Certain embodiments disclosed herein may allow a FC system to calculate a minimum and a maximum FC stack cathode inlet pressure based on different operating conditions while ensuring that the FC stack receives a desired air flow. Further embodiments disclosed herein may allow a FC system to maintain a cathode inlet air pressure within a range that protects an associated compressor from entering surge and/or overheating conditions.

Abstract: System and methods for detecting surge conditions in a compressor system are presented. In some embodiments, a method for detecting surge conditions may include receiving a plurality of flow measurements relating to a flow rate through the compressor system. Amplitude calculations may be performed based on at least one of the plurality of flow measurements to identify a possible surge condition. Frequency calculations may also be performed to identify a possible surge condition. A surge condition may be detected based on the results of the amplitude calculation and the frequency calculation and, in response, a surge detection control signal may be generated.

Abstract: Disclosed herein are systems and methods for monitoring and controlling a flow of air within a fuel cell stack. The fuel cell stack may include an air supply path to conduct a flow of air through the fuel cell. Sensors may be configured to determine parameters associated with the air supply path, such as pressure, flow rate, etc. A modeling system may further be configured to determine a modeled parameter associated with the air supply path. A control system may receive input from the one or more sensors and the modeling system to generate a baseline based on the measured parameter and the modeled parameter, determine a difference between the measured parameter and the modeled parameter, determine a change of the difference with respect to the baseline, determine that the change satisfies a criterion, and selectively implement a corrective action based upon satisfaction of the criterion.

Abstract: A system and method for operating a fuel cell stack of a fuel cell system in a vehicle when an error in cathode air flow rate is detected. The system and method include estimating a cathode air flow rate and detecting an error in the estimated cathode air flow rate. The system and method also include utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.

Abstract: A system and method for utilizing a pressurized volume of oxygen in a cathode plumbing of a fuel cell system. The system and method includes calculating an air/oxygen balance that is based on an air balance and an oxygen balance in the cathode plumbing. The system and method further include determining the number of moles of oxygen available for fuel cell chemical reactions using the calculated air/oxygen balance and drawing current from a fuel cell stack using the moles of oxygen available for fuel cell chemical reactions.

Abstract: Systems and methods to control compressor recirculation of a reactant in a fuel cell system. A recirculation valve flow setpoint value for a gas flow to the recirculation valve is calculated based on a received cathode flow setpoint. A value corresponding to a predicted recirculation valve position is generated, and can be used as a control command for changing the position of the recirculation valve to reduce the valve response time during operational transients of the fuel cell system.

Abstract: A method and device for predictively controlling the speed of a compressor used in conjunction with a fuel cell stack. Feedforward command signals are generated based on fuel cell stack setpoints that are based on stack humidification requirements. A pressure drop model uses these setpoints to determine a compressor outlet pressure setpoint change brought about by an operational transient. A recursive approach is used to solve for one or more future or desired compressor operating conditions. The results of this recursive approach are used to determine the feedforward speed command of the compressor, where known operational parameters (such as can be found on a compressor map) may be used. This permits rapid changes in compressor speed to comply with the new operating point of the fuel cell system that is brought about by the operational transient.

Abstract: Devices and methods to control a cathode backpressure valve and a bypass valve in a vehicle fuel cell system. A feedforward-based control strategy is used to control the cathode backpressure valve. The control over the bypass valve is integrated into the control over the cathode backpressure valve. Such a control strategy acts in a predictive manner to improve valve response to transitory cathode pressure and bypass flow split setpoints in the system.

Abstract: System and methods for setting pressure limits for an air supply of a fuel cell (“FC”) system are presented. Certain embodiments disclosed herein may allow a FC system to calculate a minimum and a maximum FC stack cathode inlet pressure based on different operating conditions while ensuring that the FC stack receives a desired air flow. Further embodiments disclosed herein may allow a FC system to maintain a cathode inlet air pressure within a range that protects an associated compressor from entering surge and/or overheating conditions.

Abstract: System and methods for detecting surge conditions in a compressor system are presented. In some embodiments, a method for detecting surge conditions may include receiving a plurality of flow measurements relating to a flow rate through the compressor system. Amplitude calculations may be performed based on at least one of the plurality of flow measurements to identify a possible surge condition. Frequency calculations may also be performed to identify a possible surge condition. A surge condition may be detected based on the results of the amplitude calculation and the frequency calculation and, in response, a surge detection control signal may be generated.

Abstract: Systems and methods to control fuel cell stack pressure through a cathode backpressure valve. A flow offset value is used as a capacitance term during transient operational conditions to account for discrepancies between the stack flow setpoint and the actual stack flow. The capacitance term is based on operational parameters, including stack pressure changes, stack coolant temperature and stack volume. The additional flow produced by the capacitance terms may be fed, along with pressure drop models and a valve position model to provide a more accurate prediction of valve position.

Abstract: Disclosed herein are systems and methods for monitoring and controlling a flow of air within a fuel cell stack. The fuel cell stack may include an air supply path to conduct a flow of air through the fuel cell. Sensors may be configured to determine parameters associated with the air supply path, such as pressure, flow rate, etc. A modeling system may further be configured to determine a modeled parameter associated with the air supply path. A control system may receive input from the one or more sensors and the modeling system to generate a baseline based on the measured parameter and the modeled parameter, determine a difference between the measured parameter and the modeled parameter, determine a change of the difference with respect to the baseline, determine that the change satisfies a criterion, and selectively implement a corrective action based upon satisfaction of the criterion.

Abstract: Systems and methods to mitigate surge conditions in a compressor of a vehicle fuel cell system. A first surge mitigation strategy regulates a cathode backpressure valve, if the compressor is operating at or above a threshold speed. A second surge mitigation strategy regulates a recirculation valve if the compressor is operating below the threshold speed. In one form, a feedback-based control may be used as part of a larger feedforward-based control strategy such that the mitigation is part of a reactive control strategy. The strategy may additionally be implemented in a processor-based controller.

Abstract: A system and method for utilizing a pressurized volume of oxygen in a cathode plumbing of a fuel cell system. The system and method includes calculating an air/oxygen balance that is based on an air balance and an oxygen balance in the cathode plumbing. The system and method further include determining the number of moles of oxygen available for fuel cell chemical reactions using the calculated air/oxygen balance and drawing current from a fuel cell stack using the moles of oxygen available for fuel cell chemical reactions.

Abstract: A system and method for operating a fuel cell stack of a fuel cell system in a vehicle when an error in cathode air flow rate is detected. The system and method include estimating a cathode air flow rate and detecting an error in the estimated cathode air flow rate. The system and method also include utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.

Abstract: Devices and methods to control a cathode backpressure valve and a bypass valve in a vehicle fuel cell system. A feedforward-based control strategy is used to control the cathode backpressure valve. The control over the bypass valve is integrated into the control over the cathode backpressure valve. Such a control strategy acts in a predictive manner to improve valve response to transitory cathode pressure and bypass flow split setpoints in the system.

Abstract: Systems and methods to control fuel cell stack pressure through a cathode backpressure valve. A flow offset value is used as a capacitance term during transient operational conditions to account for discrepancies between the stack flow setpoint and the actual stack flow. The capacitance term is based on operational parameters, including stack pressure changes, stack coolant temperature and stack volume. The additional flow produced by the capacitance terms may be fed, along with pressure drop models and a valve position model to provide a more accurate prediction of valve position.

Abstract: Systems and methods to mitigate surge conditions in a compressor of a vehicle fuel cell system. A first surge mitigation strategy regulates a cathode backpressure valve, if the compressor is operating at or above a threshold speed. A second surge mitigation strategy regulates a recirculation valve if the compressor is operating below the threshold speed. In one form, a feedback-based control may be used as part of a larger feedforward-based control strategy such that the mitigation is part of a reactive control strategy. The strategy may additionally be implemented in a processor-based controller.

Abstract: A method and device for predictively controlling the speed of a compressor used in conjunction with a fuel cell stack. Feedforward command signals are generated based on fuel cell stack setpoints that are based on stack humidification requirements. A pressure drop model uses these setpoints to determine a compressor outlet pressure setpoint change brought about by an operational transient. A recursive approach is used to solve for one or more future or desired compressor operating conditions. The results of this recursive approach are used to determine the feedforward speed command of the compressor, where known operational parameters (such as can be found on a compressor map) may be used. This permits rapid changes in compressor speed to comply with the new operating point of the fuel cell system that is brought about by the operational transient.

Abstract: Systems and methods to control compressor recirculation of a reactant in a fuel cell system. A recirculation valve flow setpoint value for a gas flow to the recirculation valve is calculated based on a received cathode flow setpoint. A value corresponding to a predicted recirculation valve position is generated, and can be used as a control command for changing the position of the recirculation valve to reduce the valve response time during operational transients of the fuel cell system.