State Monitoring in Fuel Cells: Temperature, Pressure, and Humidity

A method to determine relative humidity inside a fuel cell stack without using a humidity sensor. The method involves detecting supply air parameters, like temperature and humidity, along with the air flow rate. At the cathode inlet, the same parameters are measured. Using a pre-generated map, the humidifier water flow is calculated based on the cathode inlet parameters. The relative humidity is then determined from the supply air water flow, the calculated humidifier water flow, and the cathode inlet parameters. This avoids needing an internal humidity sensor.

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Calibrating fuel cell pressure sensor offsets in large scale fuel cell systems that operate continuously without frequent shutdowns, unlike fuel cells in vehicles. The system has multiple independent fuel cell modules that can be controlled individually. It calibrates pressure sensor offsets by stopping power generation of modules that need calibration. This allows calibration without affecting overall system power output. The calibration is triggered based on monitoring offset deviations or a preset time. It prevents durability issues from miscalibrated sensors in long-running fuel cells.

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A method to distinguish between reversible fuel cell degradation mechanisms like drying out versus irreversible catalyst poisoning, based on the buildup of platinum oxide (PtOx) species. The method involves monitoring the PtOx concentration in fuel cell exhaust gas. If PtOx levels increase, it indicates catalyst poisoning due to oxide formation. However, if PtOx levels decrease, it indicates drying out due to water loss. This allows targeted recovery strategies, like humidification for drying out versus platinum regeneration for catalyst poisoning, to mitigate the specific degradation mechanism.

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Estimating the amount of condensed water in the anode of a fuel cell system and controlling a drain valve based on that estimation to prevent malfunction and stack flooding. The amount of water vapor in the anode is calculated by estimating initial water, diffusion from the cathode, purging, and recirculation during fuel cell operation. The anode water vapor is subtracted from saturated vapor at temperature to get condensed water in the trap. A drain valve opens when trap water exceeds a threshold and closes when purge amount reaches a threshold.

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Correcting the offset of a hydrogen pressure sensor in a fuel cell system without opening the drain valve, which eliminates issues like excessive starting time and hydrogen emission. The method involves checking if hydrogen supply is normal, constantly supplying hydrogen, determining if the pressure sensor offset needs correction based on factors like long stop time, calculating the offset correction, and applying it during starting. This allows offset correction without drain valve opening, improves accuracy and stability, and prevents reverse voltage risk.

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Controlling humidity in a fuel cell without using humidity sensors at the cathode outlet. The method involves periodically opening a hydrogen purge valve on the anode outlet to evacuate excess water. The opening time is measured, and longer times indicate more water. This indicates high cathode humidity without needing a separate sensor. The purge time is automatically adapted based on the water amount, so only necessary purging is done. The opening time can also be used to infer cathode humidity.

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Fuel cell system with improved water management to prevent flooding and degradation while minimizing hydrogen waste. The system calculates the exact amount of water in the fuel cell stack in real time based on stack output power and a calculated maximum residual water level. This allows accurate prediction and timely discharge of water without overpurge. The controller calculates the water level using stack power data and avoids using stack hydrogen flow as a water indicator, which can overestimate water. This prevents hydrogen waste from unnecessary purging.

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A cooling control system for a fuel cell stack that cools the stack and humidifies the air supply based on the stack temperature. The system adjusts the air flow and pressure to optimize cooling and prevent overheating. It also adjusts the amount of water supplied to the stack. The control method maximizes fuel cell efficiency and performance while preventing damage from overheating.

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Estimating hydrogen concentration inside a fuel cell stack to accurately converge the hydrogen concentration on a target hydrogen concentration. The method involves predicting the initial gas amount, calculating gas crossover and purging, and estimating the current anode hydrogen concentration using the initial amount, crossover, and purging. This allows reliable estimation of hydrogen concentration in all sections, not just when current is zero, for accurate control of optimum hydrogen level.

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Fuel cell monitoring method to accurately detect issues like catalyst degradation or reactive gas distribution failures in fuel cell stacks. The method involves estimating the water content inside each cell using impedance measurements. A reference water content estimate is derived from the stack impedance. If the individual cell estimate falls below the reference by a certain threshold, it indicates catalyst degradation or gas distribution issues. This is because water content correlates with catalyst degradation and gas distribution failures. By comparing the cell estimates to the stack reference, it allows distinguishing between these issues.

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Fuel cell system with real-time steam concentration monitoring and control to improve performance and avoid damage. A humidity sensor measures the steam content of the anode exhaust stream recycle stream. This allows continuously monitoring the steam concentration in the recycle loop. A master controller uses the sensor data to adjust recycle blower flow and valve settings to optimize fuel cell operation and prevent issues like coking due to low steam-to-carbon ratios.

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Preventing false dryness detection in fuel cells when cooling the cell below a certain temperature to avoid condensation. The fuel cell system uses impedance measurement to detect electrolyte dryness. Instead of always using impedance for dryness detection, it switches to assuming wetness when cooling below a threshold. This prevents false detections due to condensation increasing resistance.

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Fuel cell vehicle that monitors hydrogen fuel fill levels to detect when a fill is incomplete and alert the user. The vehicle has pressure and temperature sensors in the hydrogen tank, and a controller that calculates the fuel amount based on those measurements. It compares the calculated fill amount to past fills and notifies the user if the current fill is lower than average. This alerts the user if there was an incomplete fill due to communication errors or using incompatible fueling equipment. The vehicle can also transmit the tank pressure/temperature data to the fueling station to enable better monitoring.

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Using the current of a hydrogen recirculation pump in a fuel cell stack as a proxy for stack humidity, to control elements that remove water from the stack. The pump current is monitored and when it indicates high stack humidity, elements like hydrogen purge rate, air flow rate, and cooling system temperature are adjusted to remove more water. This allows balancing stack humidity without adding extra sensors.

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Method for optimizing fuel cell performance and preventing degradation in fuel cell vehicles by controlling the fuel cell system based on estimated parameters. The method involves acquiring fuel cell operating data, deriving a mathematical voltage model, measuring cell voltage, and approximating the model to the measurement by adjusting parameters like reaction area, catalyst support, and internal current density. By finding the optimal parameter values through model fitting, the fuel cell system can be controlled to maintain optimal water content and prevent dry-out or over-humidification. This prevents degradation and improves performance in aged fuel cells.

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Fuel cell system and operating method to prevent uneven water distribution in a single cell fuel cell stack. The system has fuel and oxidant gas flow paths on opposite sides of the cell that cross. If humidity or stack temperature conditions indicate insufficient water at the oxidant inlet, the fuel flowrate and pressure are increased to supply more water. This prevents dry spots and clogging at the oxidant inlet. By balancing fuel and oxidant flow, water distribution is maintained.

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Fuel cell system with improved diagnosis of air system abnormalities during transient operation. The system has a pressure detector in the air system and a controller to reduce internal pressure if it exceeds a threshold during a time period. If this occurs multiple times, it indicates air system issues. This protects the fuel cell from high pressure during transient operation while still diagnosing frequent temporary pressure spikes as abnormalities.

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Diagnosing failure of the air supply system in a fuel cell vehicle to improve safety by detecting issues like air flow blockage or leaks at startup. The system uses sensors to measure air flow rate and blower power consumption during normal operation. At startup, if the measured values are outside a normal range, it indicates a fault. The system warns the driver and stops the fuel cell. This allows prompt diagnosis and fix of air supply issues before regular operation.

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