Fuel Cell Membrane Protonic Resistance Normalization
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Solution Overview
Problem
Existing methods for determining membrane protonic resistance in fuel cell stacks are hindered by variations in high frequency resistance measurements due to non-membrane contact resistances, leading to inaccuracies in membrane humidification control, especially without relying on costly and unreliable relative humidity sensors.
Innovation Solution
A method to determine the base resistance of a fuel cell stack at humidified conditions and normalize it against a reference stack, using high frequency resistance-based relative humidity control, which involves auto-learning and filtering out non-membrane contact resistances to isolate membrane protonic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high frequency resistance measurements are used to determine membrane protonic resistance, then membrane humidification control can be achieved without RH sensors, but measurement precision deteriorates due to non-membrane contact resistances
Solution Approach 1:
The patent segments the total high frequency resistance measurement into distinct components: membrane resistance and non-membrane contact resistances. By measuring and subtracting the non-membrane resistance component, the patent isolates the membrane resistance for accurate humidification control without requiring RH sensors.
Solution Approach 2:
The patent extracts and removes the non-membrane contact resistance component from the total HFR measurement. This extraction process eliminates the harmful interference from bipolar plate and connection resistances, leaving only the membrane resistance that is needed for accurate humidification control.
2Ease of operation
If non-membrane contact resistances are included in HFR measurements, then measurement simplicity is maintained, but measurement precision deteriorates due to noise from bipolar plates and connections
Solution Approach 1:
The patent extracts the non-membrane resistance component from the total HFR measurement and removes it to obtain accurate membrane resistance. This maintains the simplicity of HFR measurement while eliminating the precision-degrading noise from bipolar plates and connections.
Solution Approach 2:
The patent introduces an intermediary measurement approach where non-membrane resistance is measured separately and used as a correction factor. This intermediary step allows the system to maintain simple HFR measurements while achieving precise membrane resistance determination through mathematical correction.
3Measurement precision
If base resistance identification and normalization are performed, then measurement precision improves for membrane protonic resistance, but device complexity increases due to additional processing steps
Solution Approach 1:
The patent performs preliminary identification and normalization of base resistance values during system initialization or calibration phases. This preliminary action establishes reference values that simplify subsequent membrane resistance calculations, reducing the complexity of real-time operations while maintaining high measurement precision.
Solution Approach 2:
The patent changes the resistance measurement parameters by normalizing values against identified base resistance. This parameter transformation converts raw HFR measurements into standardized membrane resistance values, improving precision while the normalization process becomes a routine calculation rather than a complex operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate membrane humidification control by eliminating 'noise' from HFR measurements, ensuring consistent membrane protonic resistance determination and reducing the need for RH sensors, thereby improving fuel cell stack performance and durability.
Implementation Method 1
The protons pass through the electrolyte to the cathode
Implementation Method 2
determining the membrane protonic resistance of a fuel cell stack using high frequency resistance
Data Source
AI summary
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.